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Josh Track results, AFR heads
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Raleigh, NC
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Went to Rockingham Dragway last night.

Times weren't terribly impressive, but I'm not sure how the DA compares to last time I was out. Details are:

8:57 PM - 9/5/09
60- 1.949
330- 5.256
1/8- 7.925 @ 90.27
1/4- 12.112 @ 118.13

I'll wait for Beach Bum or someone to come in and post accurate DA figures before I make any more comments.
Posted on: 2009/9/6 16:59
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bogus Re: Track results, AFR heads
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waiting....
Posted on: 2009/9/6 18:22
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1989GTA Re: Track results, AFR heads
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The new power is making it even harder for you car to hook up. You need some serious rubber on that thing.
Posted on: 2009/9/6 20:36
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pr0zac Re: Track results, AFR heads
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wow.. let me dust off my credit card.. hahahahaha.. jk
Posted on: 2009/9/6 20:47
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anesthes Re: Track results, AFR heads
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Quote:

Josh wrote:
Went to Rockingham Dragway last night.

Times weren't terribly impressive, but I'm not sure how the DA compares to last time I was out.

I couldn't get the car to 60 for shit (read that as I can't drive, lol) but the fastest it went was:

1.94
7.00 @ 90
12.1 @ 118

I'll wait for Beach Bum or someone to come in and post accurate DA figures before I make any more comments.

EDIT: The slip is still in the car, I'll be back a bit later today and post all the specifics of the pass.


What was the uncorrected MPH of the TFS and AFR pass?

-- Joe
Posted on: 2009/9/6 23:19
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Josh Re: Track results, AFR heads
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First post is edited with up to date information. If my math is right, I've added DA numbers here.

Uncorrected, the TFS heads went as fast as 11.9 and 119 MPH, but on different runs on different tracks. The best the TFS heads did, on the same track I was on last night is:

TFS - DA ~2000 feet

1.814 (TFS by .135)
5.176 (TFS by .08)
7.885 @ 89.43 (TFS by .04 / AFR by .84 MPH)
12.115 @ 119.34 (AFR by .003 / TFS by 1.21 MPH)

AFR - DA ~1500 feet

60' - 1.949
330' - 5.256
1/8 - 7.925 @ 90.27
1/4 - 12.112 @ 118.13

You can see that even though I botched the 60' time, the AFR heads are gaining ground on the TFS heads almost all the way down the track, and they did out ET the other heads by a small margin, which is impressive since I was so much slower in the first 60'.

The thing that is troubling me the most is that the the car with the TFS heads on it would pretty routinely pick up 29-30 MPH from the 1/8 to the 1/4. Now, with the AFR heads, last night all it would pick up was 28 MPH, and was as low as 26 on a couple passes. Especially since I was racing in what should have been better air.

I had the same 150 lb. passenger that I had last time. I made one pass without the passenger, but I'm not a consistent enough driver to realize the benefits of losing 150 lbs. in just making a single pass.

Traction isn't an issue. I run 16 inch bias ply ET streets, and they dead hook every time. The thing that kills my short times is the motor bogs down after I launch. I haven't spent as much time in the car as I should, and the finesse of slipping the clutch slightly to effectively launch the car isn't something that I'm gifted at. I am pretty much just dropping the clutch at about 4K, the car lurches forward, bogs, and then I continue the pass. I was getting better at it with the TFS heads (as you can see by the better short times) but it's been awhile since I've been to the strip, so I'm a little rusty. I was also there by myself, no support vehicle, no trailer, nothing... 80 miles from home. If I broke, I was in trouble so that was in the back of my mind every time I staged the car.

I think with some tuning tweaks I can work the bog out of the motor on the launch. The other C4's that I've driven don't have this problem, but they have all been MAF cars as opposed to my speed density. For example, Jonescap has a 96 LT4, 6 speed car. I have made one pass in his car at the strip. On 17 inch nittos, I went 1.76. First time ever in his car. The fastest my car has ever gone, on bias ply slicks, with nitrous, is 1.74. I went nearly as fast as my best ever, with less tire, on my FIRST trip down the track in his car. With some careful tuning of the timing and fuel tables, I think I can get the car to leave better, but I haven't really explored it yet. For testing purposes, it wouldn't be fair to do that now because I didn't do it with the TFS heads. However, now that the testing is over, I will probably pursue it.

Regardless, I am little disappointed with the MPH, but I'm not willing to get too worked up about it until I hit the track again and have a greater sample size from which to draw an opinion.

In the end though, I was hoping for more this track trip.
Posted on: 2009/9/6 23:46
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jonecap Re: Track results, AFR heads
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Dude, you just need an opti


Seriously, you just need to get some more track time with it and better air. Next time, we'll bust out the trailer too so you won't worry too much about carnage. With your power, low 11's are in the car, we just need to dial it in.

Did you datalog any passes?
Posted on: 2009/9/7 0:12
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'02 Z06 - 11.58 @ 117.40 CAI & ET Streets only...

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10.72 @ 128.90 on the jug ;)

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Josh Re: Track results, AFR heads
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Don't have a laptop, it belonged to the last girl... Once she moved out, it moved out too, lol.
Posted on: 2009/9/7 0:24
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anesthes Re: Track results, AFR heads
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Quote:

Josh wrote:
First post is edited with up to date information. If my math is right, I've added DA numbers here.

Uncorrected, the TFS heads went as fast as 11.9 and 119 MPH, but on different runs on different tracks. The best the TFS heads did, on the same track I was on last night is:

TFS - DA ~2000 feet

1.814 (TFS by .135)
5.176 (TFS by .08)
7.885 @ 89.43 (TFS by .04 / AFR by .84 MPH)
12.115 @ 119.34 (AFR by .003 / TFS by 1.21 MPH)

AFR - DA ~1500 feet

60' - 1.949
330' - 5.256
1/8 - 7.925 @ 90.27
1/4 - 12.112 @ 118.13

You can see that even though I botched the 60' time, the AFR heads are gaining ground on the TFS heads almost all the way down the track, and they did out ET the other heads by a small margin, which is impressive since I was so much slower in the first 60'.

The thing that is troubling me the most is that the the car with the TFS heads on it would pretty routinely pick up 29-30 MPH from the 1/8 to the 1/4. Now, with the AFR heads, last night all it would pick up was 28 MPH, and was as low as 26 on a couple passes. Especially since I was racing in what should have been better air.

I had the same 150 lb. passenger that I had last time. I made one pass without the passenger, but I'm not a consistent enough driver to realize the benefits of losing 150 lbs. in just making a single pass.

Traction isn't an issue. I run 16 inch bias ply ET streets, and they dead hook every time. The thing that kills my short times is the motor bogs down after I launch. I haven't spent as much time in the car as I should, and the finesse of slipping the clutch slightly to effectively launch the car isn't something that I'm gifted at. I am pretty much just dropping the clutch at about 4K, the car lurches forward, bogs, and then I continue the pass. I was getting better at it with the TFS heads (as you can see by the better short times) but it's been awhile since I've been to the strip, so I'm a little rusty. I was also there by myself, no support vehicle, no trailer, nothing... 80 miles from home. If I broke, I was in trouble so that was in the back of my mind every time I staged the car.

I think with some tuning tweaks I can work the bog out of the motor on the launch. The other C4's that I've driven don't have this problem, but they have all been MAF cars as opposed to my speed density. For example, Jonescap has a 96 LT4, 6 speed car. I have made one pass in his car at the strip. On 17 inch nittos, I went 1.76. First time ever in his car. The fastest my car has ever gone, on bias ply slicks, with nitrous, is 1.74. I went nearly as fast as my best ever, with less tire, on my FIRST trip down the track in his car. With some careful tuning of the timing and fuel tables, I think I can get the car to leave better, but I haven't really explored it yet. For testing purposes, it wouldn't be fair to do that now because I didn't do it with the TFS heads. However, now that the testing is over, I will probably pursue it.

Regardless, I am little disappointed with the MPH, but I'm not willing to get too worked up about it until I hit the track again and have a greater sample size from which to draw an opinion.

In the end though, I was hoping for more this track trip.


The ET is more of a representation of the driver + traction. MPH should be pretty consistent no matter what, and really shows how much power the car is making.

In regards to launching a manual, it takes time to learn. For the purpose of this test, I'd probably WOT and slip the clutch out of the gates to keep out of bog.


As of right now, if I knew nothing about the combos, just looking at the time slips I'd say the TFS combo made more power based on the MPH at the end of the track. Obviously the tune is botched for both combos, so it makes it kinda hard to evaluate.


Although, with all of that said, I believe the AFR's were cheaper out of the box than having the TFS heads modified, so since performance is about on par with a bad tune we can say the AFR is the better value.

-- Joe
Posted on: 2009/9/7 1:55
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BeachBum Re: Track results, AFR heads
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Nice testing Josh !

On this final test, I'd have to analyze it closer to maybe help offer some insight and I don't have the time tonight. But the first thing that jumps out at me is that the AFR's were quicker than the TF's all the way down the track once you got past the 60 ft mark.

Here is a summary of acceleration:

60ft to 660 ft mark

Trick Flows = 3.362 seconds
AFR = 3.307 seconds

660 ft to 1320 ft mark

Trick Flows = 4.23 seconds
AFR = 4.187 seconds

So, you were definitely running faster with the AFR's than the Trick Flows once you got yourself going and in fact, substantially quicker.... for you to run a 60 ft time .13 slower, yet catch and pass the other timeslip is not an easy thing to do.

To put the above in perspective, at your speeds, that 1/2 tenth difference the 2nd half of the track is approxmiatley 8-9 ft..... imagine yourself pulling on yourself 8-9 ft over that last 4 seconds of the track and you'll see what was happening.

I do not know why with the MPH, as you can see above, the AFR's were pulling hard. But, I've had it happen to me on occasion for a couple of reasons, one of which I was too aggressive with the timing and it would detonate at the top of the track in high gear, this will hurt MPH more than et if its at the top.....I've also seen the same thing with a headwind.

But, I dunno, just guessing.... I wouldn't worry about it, go work on those 60's..... thats where 90% of your et improvement lies and I imagine you'll be setting new personal records all winter with the really good air just around the corner.

One more thing you want to think about with your et, is that for every tenth you improve on your 60 ft, you will typically receive 1.5-2 tenths total et improvement.... your prior 60 ft was .135 quicker.... imagine if you ran that 1.81 60 ft last night.... would have turned your 12.112 into a 11.8 or 11.9 without a problem.

If you have time, post both timeslips with all incrementals including 330 ft and 1000 ft.... we can learn a lot from this.


gotta run !
Posted on: 2009/9/7 6:02
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CentralCoaster Re: Track results, AFR heads
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Yeah, 60' times are everything. About 2 tenths here for every tenth off my 60' time.

You can't really compare them until you get similar 60' times. Unless of course, the parts are having some significant effect on your launch. Are they?
Posted on: 2009/9/7 13:59
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CentralCoaster Re: Track results, AFR heads
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Quote:

anesthes wrote:

The ET is more of a representation of the driver + traction. MPH should be pretty consistent no matter what, and really shows how much power the car is making.


True on mph, but I think ET also improves when you run a setup with more power under the lower end of the curve. I see it all the time in my vette, makes way less peak hp than others out there, but runs similar ET's. It's definitely an 1/8 mile racer for that reason. The AFRs gained a lot of ground early and had higher trap speed at the 1/8, but not at the end, even with better E/T on the last half.
Posted on: 2009/9/7 14:04
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Josh Re: Track results, AFR heads
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I don't think the heads are having an effect on the short times, at least not a negative one. I attribute that to driver ability and the bog that haunts me when I come off the line.

As a data point, with my car, every .1 reduction in 60 foot time has always been worth a reduction of .159 in ET. This has held true from when my car was stock and running 13's, all the way through into the 11's. On nitrous, on motor, etc... Always, with my car, .1 faster sixty equals .159 faster ET.

I'm not sure why the car would have slowed the last half of the track. You can see that the AFR's are gaining ground on the TFS after the 60', and as mentioned have attained more MPH by the 1/8 mile mark. I don't know why the car was slower out the back end.

There is only 32 degrees of timing in it right now, so I can't imaging that it's knocking and pulling timing in high gear, but maybe???
Posted on: 2009/9/7 14:11
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CentralCoaster Re: Track results, AFR heads
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Well, it still gained in ET on the 2nd half.

I guess my point is, the car was clearly making more useful power if it made up ground on the TFS. Mph doesn't win races maybe you hit your brakes to sandbag the test. And the conspiracy theories begin!
Posted on: 2009/9/7 14:42
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pr0zac Re: Track results, AFR heads
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what valve springs and retainers are you using? wheni had that cam in my lt4 it would do the exact same thing..
Posted on: 2009/9/7 14:42
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Josh Re: Track results, AFR heads
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They are the upgraded beehive springs and retainers from AFR. I don't think it's a spring/valve control issue, but it's possible I suppose.

Later this week I'll check and see if I have a caliper hanging up or something.
Posted on: 2009/9/7 14:58
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dan0617 Re: Track results, AFR heads
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I've found that tire spin out of the gate = higher mph. Most have found that also. I've also found, though, that when you bog a stick, or easily roll into an auto, the 60' is slower AND the mph is slower. If you had spun to that awful 60' and still mph'd slower I'd be looking for a problem. Since you bogged it and ended up with that result, all you need to do is get rid of the bog.

That said, chances are you need to add some lower rpm WOT timing. Probably best to do it in the PE timing table because if you add it in the normal timing table you might find it detonating when lugging up a hill at lower rpms on the street/highway. For every few degrees of timing you add you will need to add some fueling to keep it from being lean. When you drop the clutch, about what rpm does it drop to? Find that out, then from about 4000 down to or below that rpm add all the timing you can and add the fueling as necessary. I'll bet you will find that bog will turn into tire spin, or a wicked 60' time if they don't spin. You may find that you need more timing in your launch rpms than you do at and above your peak torque area. Might need your overall timing curve at WOT to go up fast, ramp back down at your peak torque, then back up some as you approach and pass your max hp and hit your shift point.

I have my timing cut back below my peak torque rpms to help keep me from tire spinning or snapping my rear. I honestly think I could bring my timing "all in" much earlier and make alot more power but I'm cutting a mid 1.5 60' and could do better with a harder launch so I truly don't want any more power on launch right now. I did alot of playing with WOT timing in the normal and in the PE timing table to get it dialed in, and I was surprised at what can be gained/lost with timing and subsequent fueling changes at launch.
Posted on: 2009/9/7 16:01
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ยด89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's.
On spray, 10.55 @ 132.78, 1.55 60 ft.
On motor, 12.08 @ 113.15, 1.66 60 ft.
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BeachBum Re: Track results, AFR heads
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If I can see those 330's and 1000's ft et's off both timeslips, it will tell us a lot. Including on what to make of the MPH.

In my personal experience of years racing both an auto and stick..... wheel spin coming out of the hole does not have a big effect on mph provided you hook it up in 1st gear and you are able to pull through the top of 1st gear hooked-up..... but if I would spin through 1st gear and into 2nd, MPH came down very hard. Reason being, you are wasting precious acceleration feet.... the same applies for a bog, you jump out and have a bog 20 ft out for example, car actually decelerates for a moment before re-accelerating.... this is wasted track. You now have 1300 ft instead of 1320 of track to accelerate to whatever that MPH is. So that would hurt both tests if you were doing it on both.

Something else that is important is crisp, clean and fast shifting.... this will effect MPH.... whenever that clutch is engaged, you are not accelerating, and the longer it is engaged, the less amount of ashpalt you have to accelerate to your MPH when you understand you were basically coasting for a percentage of the track instead of accelerating. I think Manual racing is fun and I did a lot of once upon a time.... but definitely more of a challenge.

Josh, at MPH's around 120 MPH and running on ET Streets, you should have et's around 11.5-11.6 even with a manual..... 1.6x 60 fts should be the norm. I think you definitely need to slip that clutch on a 5000 rpm dump.....or in otherwords, take it up to 5000 rpm, dump the clutch 1/2 way, and slip it the rest for the next 30 ft..... do anything to avoid that bog, you'll see your 60 fts and that et rocket down if you can. A friend of mine used to have a 2002 Z06, mild mods, we got it down to a best of 11.5x @ 118 mph by doing the above.

good luck !
Posted on: 2009/9/7 16:56
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1989GTA Re: Track results, AFR heads
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"Something else that is important is crisp, clean and fast shifting...."

Also the rpm at which you are shifting. Data Logging would provide a lot of questions but I guess you can't do that. With the new heads you need to be shifting at a higher rpm to take advantage of the horsepower curve.
Posted on: 2009/9/7 17:05
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pr0zac Re: Track results, AFR heads
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i too would bog off the line. it really need to be revved up not to. but i only had street tires so anything over 2500rpm and it was spinning its balls off. my clutch is very unforgiving.. its all or nothing. it drove me nuts and i ended up removing the engine before getting to run it with slicks.
Posted on: 2009/9/7 17:59
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anesthes Re: Track results, AFR heads
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Quote:

CentralCoaster wrote:
Well, it still gained in ET on the 2nd half.

I guess my point is, the car was clearly making more useful power if it made up ground on the TFS. Mph doesn't win races maybe you hit your brakes to sandbag the test. And the conspiracy theories begin!


Actually some brackets MPH wins, not ET but beyond that my point was it's hard to compare data because he's not an experienced (no disrespect) racer with a manual trans.


I like MPH because I don't like roll cages. 11.50 is the fastest I get to go, but I can trap up to 130 I think until I'm forced into the next bracket. Although I do have a bigger car now, I still don't want to put a cage in it.

Josh's 383 with the AFR heads should be a low 11 second if not high 10 second combo with the right driver, I'd think. C4 is a damn light car.. If you can keep the rear end from breaking apart, it should be really ET capable. Figure I'm about 800lbs heavier in my fbody. I probably need another 100hp to run the same ET

-- Joe
Posted on: 2009/9/7 18:59
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dan0617 Re: Track results, AFR heads
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I'd think 11.70 is easily doable, or possibly an 11.50. He gets into the 10's on motor with that setup and I'm going to buy his trans and clutch from him and put it in mine!
Posted on: 2009/9/7 19:33
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ยด89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's.
On spray, 10.55 @ 132.78, 1.55 60 ft.
On motor, 12.08 @ 113.15, 1.66 60 ft.
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Josh Re: Track results, AFR heads
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I dunno, I think 11.30-11.40 or so at 125 is probably the upper end of the combo I have now. I didn't expect to run those times right out of the gate, but I was expecting some 11.80's or so. It'll come around as I get more seat time.

Despite outward appearances, I do have a fair amount of drag strip experience, probably between 5,000-10,000 passes over a decade or so. I don't know that .15 difference in sixty foot invalidates the data, but to each their own. I'm not down playing the importance of over a tenth in foot times, but anyone with a modicum of drag strip experience should be able to look at the times and draw their own conclusions.

There's a good bit more to the poor short times than anyone here realizes, but none of it has any bearing on the tests, so I'm not going to discuss it right now. I know that sounds defensive (which I'm not trying to be, there is most definitely room for improvement in my driving), but I'm just not prepared to type the million word essay that it would take to explain it.
Posted on: 2009/9/7 20:42
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dan0617 Re: Track results, AFR heads
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I'll agree 100% that the tests were conclusive as to the gains from the AFR heads. One can speculate all day about the 60' times effect on the pass, but as stated above the AFR's were quicker from segment to segment on the track, backing up the dyno results.

I am impressed at your success this early in the tuning process. I originally thought (when on the TFS heads and until I read this thread) that your 60' times were traction limited, rather than power or launch technique limited. I'm sure with some tuning of timing and fueling in the right areas and learning the launch style that the combo likes you will get to where you want to be.

As a side note, I wonder what the drop down rpm is when you bog. If it isn't too low, sounds like that would be the perfect time to hit the spray switch and not blow the tires off. Maybe you are set up more for nitrous already then you know you are??!! And since your car is a street car maybe that bog will give you that much more traction on the street?? Lots to consider, but, no more need to consider which heads to run!
Posted on: 2009/9/7 21:49
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ยด89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's.
On spray, 10.55 @ 132.78, 1.55 60 ft.
On motor, 12.08 @ 113.15, 1.66 60 ft.
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88BlackZ51 Re: Track results, AFR heads
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It is very interesting that so far the TFS heads have out mph the AFR heads, but the E.T. goes by a hair to the AFR heads.

I think most thought you would gain 2 mph, and possibly 3 mph in trap speed, and I was one of those guys.

Still kind of puzzling given the dyno charts, but it was still a good read.
Posted on: 2009/9/8 11:11
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dan0617 Re: Track results, AFR heads
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If I was a bettin man, I'd wager anyone that the next time out he will be 2-3 mph faster than his fastest pass yet. I was puzzled until I realized the short times were from bogging, not spinning. Now I'm 100% sure the 1/4 mile ET and MPH will be better once dialed in. This is one of those things where it won't show on a dyno but real world results tell you where work needs done.
Posted on: 2009/9/8 14:35
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ยด89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's.
On spray, 10.55 @ 132.78, 1.55 60 ft.
On motor, 12.08 @ 113.15, 1.66 60 ft.
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Josh Re: Track results, AFR heads
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...wrong thread...
Posted on: 2009/9/8 14:56
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CentralCoaster Re: Track results, AFR heads
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Quote:

dan0617 wrote:

I originally thought (when on the TFS heads and until I read this thread) that your 60' times were traction limited, rather than power or launch technique limited.


Those 60' times have to be traction limited. I can run those short times in my stock '85. Bogging simply means the driver was being too conservative trying to not break traction. Every car bogs if you don't drop it from a high enough rpm, I wouldn't call that a tuning issue unless the car runs like a sack of shit around town.
Posted on: 2009/9/8 16:36
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BeachBum Re: Track results, AFR heads
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Quote:

dan0617 wrote:
If I was a bettin man, I'd wager anyone that the next time out he will be 2-3 mph faster than his fastest pass yet. I was puzzled until I realized the short times were from bogging, not spinning. Now I'm 100% sure the 1/4 mile ET and MPH will be better once dialed in. This is one of those things where it won't show on a dyno but real world results tell you where work needs done.


I think Josh did better than we know on that pass..... once past the 60 ft time, the new set-up gained hard at every increment. 6 hundredths from 60 ft to 330 ft, 4 hundredths from 330 ft to 660 ft and 5 hundredths from 660-1320.... and yet had a lower MPH, which is hard to do.....

Its hard to gain et on a car in the 2nd half of the track, but yet run a slower mph.....it actually doesn't add-up, on my simulator, if you gain 1/2 tenth in the 2nd half of the track at 120 mph, (8.8 feet), that means you averaged apprxomiately 1.5 mph faster in that same distance... and yet his MPH is lower on the slip. Which can only mean, either the MPH timers gave a false number, or he let off the gas before the back stripe or at very end of the track detonation or fuel pressure dipped right before the end.

Your timeslip MPH is the average MPH you ran in the last 66 ft of the track. Typically a car like Joshs is entering the 66 ft timers at 118, exiting at 120, thus will have a 119.0 mph on the slip. If there is a dip anywhere in their, the MPH will of course drop..... basic mathematics tells us this happened based upon the time he covered that distance per the timeslip. The 1000 ft et would have given us a better indication of how hard it dropped that last 320 ft. But who knows....
Posted on: 2009/9/8 16:42
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BeachBum Re: Track results, AFR heads
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As a final note, despite whatever happened to you at the end of the track, the AFR's averaged 107.65 mph the 2nd half of the track, the prior set-up averaged 106.38 mph.

Just interesting....
Posted on: 2009/9/8 17:03
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CentralCoaster Re: Track results, AFR heads
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Quote:

BeachBum wrote:

Your timeslip MPH is the average MPH you ran in the last 66 ft of the track.


I though the trap was 50' long...?
Posted on: 2009/9/8 17:16
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BeachBum Re: Track results, AFR heads
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Quote:

CentralCoaster wrote:
Quote:

BeachBum wrote:

Your timeslip MPH is the average MPH you ran in the last 66 ft of the track.


I though the trap was 50' long...?


No, its 66 ft, for both the 1/8th and 1/4.
Posted on: 2009/9/8 17:25
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Josh Re: Track results, AFR heads
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Here's my best attempt at explaining the poor 60 foot times:

First, my physical limitations. I have a titanium femur in my left leg from a motorcycle accident. The damage to my leg is/was pretty severe, and while I have near normal function, the finesse associated with gently yet quickly slipping the clutch is difficult for me. The fine motor skills in my leg are less than perfect, and you can imagine the impact that has on drag racing a stick shift car. Large movements, clutch to floor and back out for example, are still as quick as ever; but fine motor control has suffered.

Even with this limitation, I've been able to go mid 1.8's on street tires with my C4. With careful throttle control, and doing what I can with the clutch, on street tires mid to high 1.8's eventually became the norm. As I made mods, and increased power, wheel spin became more an more difficult to control.

I tried drag radials, and while the hook was tremendous when compared to the street rubber, I found myself either bogging from leaving at too low of an RPM, or spinning. Once in a spin, if I lifted off the throttle at all the tires would bite and pull the motor down, causing a bog. In the end, I was only able to get the same mid 1.8's out of drag radials, but it was much harder on the car because I had to come out at a much higher RPM.

In the past, before the leg, I had great luck with bias ply ET streets. I got some for this car, and have liked them thus far. The only problems I have had are all breakage related. The grip from the tires is tremendous, and applying power suddenly (in a clutch drop scenario) with tires that do not spin is a great way to find the weak link.

Anyway, I digress... My launch technique is as follows:

-Burnout, stage. Stage as shallow as possible.
-4,000 RPM in first gear, clutch on the floor.
-Release clutch in as controlled a manner as possible and squeeze throttle to the floor.

What happens is that I let the clutch out too quickly. The process would look like this in storyboard form:

-Clutch is released quickly, accelerator is on the floor.
-The car lurches forward, tires do not spin.
-The car has moved 3-5 feet, and is now traveling at ~10 MPH.
-The clutch is out, and not slipping. The tires are not slipping either.
-Since the tires are going 10 MPH, and there is no slip in the drive train, the engine is going to be pulled down to an RPM that equates with 10 MPH.
-The engine bogs to whatever RPM equates to 10 MPH.
-The motor recovers, and starts to build RPM again.

I could correct this with a bit longer clutch slip, a slight amount of wheel spin, or more torque/horse power.

The tune is exacerbating the problem because:

-When the RPM comes down, it falls to a point where the timing backs off from 32 degrees. At 2700 for example, I want to say there is only about 20 degrees of timing in the tune. This kills the power at that RPM, and really limits the engines ability to pull itself out of the bog.

I can help this issue with tuning by maybe pulling some fuel out at the appropriate point, and adding timing. This is something I have yet to do with this combo.

In other C4's that I've raced (all MAF cars) I've never experienced the bog that I get in my car. I do the same launch technique, and go mid 1.7's without an issue. With some seat time in one of these cars, mid 1.6's would most likely become the norm.

If I can correct the tuning issues, and let the engine more successfully pull itself out of the bog, I can start to make adjustments to my technique to correct the issue. The adjustments to my clutch pedal action are difficult, but not impossible.

Like I said, the times will come around, it'll just take me some time to dial in the car, and dial in my leg.
Posted on: 2009/9/8 18:00
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CentralCoaster Re: Track results, AFR heads
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I assume you ran multiple passes with both setups so far.

Can you post the other timeslips? Out of those runs there's got to be some with similar 60' times. I think the point here is to remove the variable of your driving from the equation, not to criticize it. We all know it takes at least 30-40 passes to start getting the most out of a setup. And it takes even longer if you can only get 3 runs in at a time and have to wait 1-2 hours in between to apply what you learned on the last pass. By the time you start figuring anything out you have to head home. Plus if I can only get 3 runs in a night, I'm afraid to experiment because I don't want to "waste" a run.
Posted on: 2009/9/8 20:11
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BeachBum Re: Track results, AFR heads
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Not sure what is happening on the other forum, but its all good..... dialing in a set-up is A-typical stuff and quite frankly, perhaps the funnest part of a new set-up is slowly dialing that et down. The funnest I ever had racing was in the beginning when it seemed every modification I made, worked and lowered my et.... always fun to find a new best most times out to the track.

Manual transmissions are a lot funner to race in my opinion, but of course infinetely harder too.... this is normal stuff, you'll have your et lowered down to whatever you're hoping for in no-time at all..... enjoy it!... this is the fun part. As far as racing tips from people.... most are just trying to be nice regardless of the quality of the tip, they don't mean anything by it.... or at least I do not.

good luck and ignore everybody who might be negative and just have fun with your new "very fast" set-up !
Posted on: 2009/9/9 0:11
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Josh Re: Track results, AFR heads
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Digi cam is messed up, here's the breakdown:

TFS runs:

8:33 PM

1.846
5.230
7.941 @ 91.25
10.246
12.173 @ 116.99

9:08 PM

1.956
5.319
8.001 @ 90.51
10.285
12.195 @ 118.03

10:32 PM

1.863
5.224
7.923 @ 89.57
10.227
12.155 @ 116.95

~11:00 PM

1.814
5.176
7.885 @ 89.43
10.193
12.115 @ 119.34

---------------------------

AFR:

8:57 PM

1.949
5.256
7.925 @ 90.27
10.205
12.112 @ 118.13

9:41 PM

2.020
5.443
8.144 @ 89.62
10.438
12.354 @ 117.67

10:03 PM

1.944
5.277
7.967 @ 90.01
10.251
12.160 @ 118.05

10:09 PM

1.964
5.369
8.088 @ 90.87
10.403
12.336 @ 116.64
Posted on: 2009/9/9 1:21
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Josh Re: Track results, AFR heads
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Maybe someone can format that and make it a bit easier to read???
Posted on: 2009/9/9 1:22
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pr0zac Re: Track results, AFR heads
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you didn't have the bog issue with the tfs heads correct? it just hooked and ran? i found that for the street which i did most of my "driving" :-).. a 2 step did wonders for ass raping people out of the hole which overcame my bog issue cause i could hold the gas pedal to the floor. i unhooked my horns and ran the two step activation wire off the horn wire allowing me to be able to hold the wheel and launch control with one hand the shifter and the nitrous button in the other. i have a momentary switch that comes up through the shift boot and i can squeeze it against the ball.
Posted on: 2009/9/9 1:40
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Josh Re: Track results, AFR heads
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The issue wasn't nearly as bad with the TFS heads.
Posted on: 2009/9/9 1:58
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88BlackZ51 Re: Track results, AFR heads
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Alot of guys seem to think that you will get the tune dialed in, and trap more mph then the AFR, and I am one of them.

Goodluck!

Edited by CentralCoaster
Posted on: 2009/9/9 14:30
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TonyMamo Re: Track results, AFR heads
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Quote:

Josh wrote:
The issue wasn't nearly as bad with the TFS heads.

Josh,

My guess is the bog was more related to track prep variance than anything else. Assuming the tune was dialed to take advantage, a smaller runner with more flow will always be more responsive and make better torque down low (and up high for that matter).

Once again, the pitfalls of track testing without having a large sampling of data (many passes and many trips to the track) to pour over and make conclusions from.

-Tony
Posted on: 2009/9/9 14:42
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BrianCunningham Re: Track results, AFR heads
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Nothing like making a run down the track only to find water that some halfwit left there because he drove through the water box!
Posted on: 2009/9/9 15:21
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pr0zac Re: Track results, AFR heads
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Quote:

88BlackZ51 wrote:
Alot of guys seem to think that you will get the tune dialed in, and trap more mph then the AFR, and I am one of them.

Goodluck!

Edited by CentralCoaster
i would love to know what this originally said..
Posted on: 2009/9/9 17:27
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anesthes Re: Track results, AFR heads
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Quote:

TonyMamo wrote:
Quote:

Josh wrote:
The issue wasn't nearly as bad with the TFS heads.

Josh,

My guess is the bog was more related to track prep variance than anything else. Assuming the tune was dialed to take advantage, a smaller runner with more flow will always be more responsive and make better torque down low (and up high for that matter).

Once again, the pitfalls of track testing without having a large sampling of data (many passes and many trips to the track) to pour over and make conclusions from.

-Tony


Could be anything. Too much AE, spark curve, driver.

-- Joe
Posted on: 2009/9/9 17:49
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dan0617 Re: Track results, AFR heads
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Quote:

pr0zac wrote:
Quote:

88BlackZ51 wrote:
Alot of guys seem to think that you will get the tune dialed in, and trap more mph then the AFR, and I am one of them.

Goodluck!

Edited by CentralCoaster
i would love to know what this originally said..


Good catch prOzac. I missed that little edited by CC. Now I'd love to know too!
Posted on: 2009/9/9 18:44
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ยด89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's.
On spray, 10.55 @ 132.78, 1.55 60 ft.
On motor, 12.08 @ 113.15, 1.66 60 ft.
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CentralCoaster Re: Track results, AFR heads
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88black and Josh were expressing their true love for each other. Now can we move on?
Posted on: 2009/9/9 21:40
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pr0zac Re: Track results, AFR heads
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but josh has afr heads.. so ricky has to be on his team.
Posted on: 2009/9/9 23:17
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Josh Re: Track results, AFR heads
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Enough, back to the topic.

The 2 closest 60' foot times are a 1.956 and a 1.949. Those 2 runs compare as follows:

60' - AFR by .007
330' - AFR by .063
1/8 - AFR by .076
MPH at the 1/8 - TFS by .24
1000' - AFR by .08
1/4 - AFR by .083
MPH at the 1/4 - AFR by .10
Posted on: 2009/9/10 0:48
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pr0zac Re: Track results, AFR heads
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that is really close..
Posted on: 2009/9/10 2:22
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88BlackZ51 Re: Track results, AFR heads
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it appears that josh is trying to sell his car. i'd assume we wont really know the full potential of these tests.
Posted on: 2009/9/19 19:08
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