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| BrianCunningham | Post of the day | ||
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Posted on: 2009/4/6 18:07
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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| BillH | Re: Post of the day | ||
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The Stig Moderator
 
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Why?
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Posted on: 2009/4/6 23:58
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Every man dies but not every man lives. |
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| CentralCoaster | Re: Post of the day | ||
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I see a few leghumpers mentioning all the ways the test unfairly disadvantages the SW headers. I doubt they'd have any incentive to make the product look bad.
I would like to see the area under the curve. The guy claiming he picked up a full second with just exhaust on his L98 is laughable. |
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Posted on: 2009/4/7 2:35
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1985 Z51, ZF6 |
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| Matatk | Re: Post of the day | ||
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Webmaster
 
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Me too. But he said SLP & headers. What else went along with that? Matthew |
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Posted on: 2009/4/7 11:48
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| anesthes | Re: Post of the day | ||
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Master Guru
 
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I don't know why. My friends '89 GTA, all we did was headers (shorty hedman) and a flowmaster catback, repin to speed density and a tune by me with a better advance curve, a little lean transition and a decent AFR up top. Car went from mid 14s to mid 13s.. That's a second, with the only 'mod' being the exhaust. Unless you count tuning a mod, but I count it as just what you do after you change something.. If guys are just throwing parts at a car with hopes it will improve but never actually getting into the prom things will never work as expected. -- Joe |
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Posted on: 2009/4/7 12:07
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| mseven | Re: Post of the day | ||
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Tuning was always black magic, the unknown art .....the reason is because most have never delved into tuning it themselves to understand what is involved, the state of the current tune and just how dramatic the effect/s can become. I also think in part it was due to the fact many believed MAF cars could comp. enough, and if a tune was really needed purchasing one from a reputable tuner would accomplish the goal....just plug and play.
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Posted on: 2009/4/7 13:42
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| xccter | Re: Post of the day | ||
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Senior Guru
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Never been a fan of headers.
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Posted on: 2009/4/7 13:49
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´71 350/270 L48 Coupe Numbers Matching Ontario Orange 4 spd, Mid-year side pipes, deluxe black leather, ac, ps, pb, pw, tilt/tele steering wheel. 93k miles. Original rotors still riveted to the hubs! NCRS #48337 |
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| Durango_Boy | Re: Post of the day | ||
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Elite Guru
 
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A point to add, is that headers sometimes add benefits other than power. Exhaust note and sound is a BIG factor for me. Sure the flow is important but I like the way exhaust sounds...almost giving a car a more unique personality. I put shorty headers on my Durango with true dual exhaust and MAN the sound is fantastic. Same with my old red '77. It had stock exhaust when I got it. I changed to headers and true duals and the sound alone changed an otherwise plain red Vette into something MUCH nicer to see and hear.
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Posted on: 2009/4/7 13:53
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| bogus | Re: Post of the day | ||
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Grand Imperial Pooh-Bah
 
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As for an L98 picking up a second, I actually wouldn't be surprised. Think about this: Old 87+ L98 with bad precats and stock center cat. Remove all of the above, put on headers and bullet cats, x-pipe and I see a 1 second gain. Especially if retuned.
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Posted on: 2009/4/7 14:46
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| dan0617 | Re: Post of the day | ||
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Does make you wonder how many modified cars are running around with "less than optimal" timing and air/fuel ratios. And how many are running around on the ragged edge, just because they bolted parts on and have no idea what is going on. Any time I ever modify another car an air/fuel gauge will be my first purchase! |
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Posted on: 2009/4/7 17:44
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´89 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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| CFI-EFI | Re: Post of the day | ||
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Senior Guru
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I am a fan of headers, especially the proper headers for the application, but wild assed claims crediting headers for all the gain coming from a complete exhaust system overhaul, where certain parts (the cats) could have been severely clogged, is nuts. RACE ON!!! |
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Posted on: 2009/4/8 14:55
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| bogus | Re: Post of the day | ||
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Grand Imperial Pooh-Bah
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I don't agree.
The L98, at it's peak, was rated at 250hp. The LT1, at 300hp. The redline went up about 700RPM. The LT1 had a much better intake, but it also had a significantly improved exhaust. I cannot ignore that improvement. The later style L98 exhaust, with precats and a center cat is just so restrictive. Additionally, the L98 manifolds are not as good as the LT1 cast units. I agree, clogged cats are a serious performance killer, but a better breathing exhaust will gain power. Especially when it is as restrictive as the L98 system. I will add, tho, that most (if not all) cat-back systems are not power adders. My Corsa system fixed the resonance issues inherent to the C4 cabin. However, it didn't make my car any faster. And with an LT1, I doubt headers would help my otherwise stock engine. Cam, heads, higher ratio rockers, I could see a benefit. On the L98, I feel tho, that the additional breathing would be beneficial. |
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Posted on: 2009/4/9 14:45
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| 1989GTA | Re: Post of the day | ||
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Guru
 
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I had made a few intake mods to my 1989 GTA before I added the SLP 1 5/8" Tri-Y headers and cat back system. I have to say that has been the single most seat of the pants improve I have made over the years. It was very noticable. I have made a lot of mods over the years and I'm currently around 460hp at the motor but none were as much as that.
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Posted on: 2009/4/9 17:45
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| BrianCunningham | Re: Post of the day | ||
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Senior Guru
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GTA's have those log manifolds, a really big restriction.
That's why the f-body engines were never rated the same as the Corvette engines. |
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Posted on: 2009/4/9 18:48
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_________________
Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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| anesthes | Re: Post of the day | ||
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Master Guru
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Heads could be a determining factor as well. I know the '128 vette heads do not flow as well as the iron L98 fbody heads, but I believe the '113 vette heads are much better on the flowbench. If I recall, vette has a higher compression ratio too, although most of that is probably lost with the aluminum head. What always got me was the axle ratios on the vettes.. 2.59, 3.07, and 3.54.. Fbody came in 3.08, 3.23, 3.42, and 3.73. 2.59 is absolutely useless. -- Joe |
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Posted on: 2009/4/10 11:50
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| anesthes | Re: Post of the day | ||
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Master Guru
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A lot of guys bring up clogged cats. It's an interesting argument, and while it holds true in theory, 99.9995% of all fbody owners punched the cats out years before putting headers on or removed them completely. The comparison I was referring to, was on a car with the cat removed. The stock Fbody exhaust is just terrible. I'd expect the gain on a C4 to be a little less, but still. I must say, I'm impressed with the stock LT1 "catback". nice and quiet and doesn't seem to be holding back my motor at all. -- Joe |
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Posted on: 2009/4/10 11:53
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| anesthes | Re: Post of the day | ||
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Master Guru
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Tons and tons. Some of the so called "experts" on these forums can't even begin to tune the car. They write long winded posts about all sorts of tech (which I won't dispute), however when it comes to the REAL important thing - spark and fuel, they lay ignorant and expect the ECM to just 'do it'. So it seems with trends, the 'norm' is to spend thousands in parts and only make the car a little faster, where in reality a 'tuner' will probably spend less on an ideal combo and get the most he/she can out of it by providing the BEST AFR and advance curve. -- Joe |
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Posted on: 2009/4/10 11:56
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| dan0617 | Re: Post of the day | ||
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Senior Guru
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I couldn't agree more with this. I removed my entire L98 exhaust system a little at a time. First was headers and custom midpipes with no cats, tieing into stock catback. Felt a big power gain, but have no idea how much of it was the headers and how much of it was the removal of the likely partially clogged cats. Resonance was bad. I purchased a used stock LT1 catback, and installed it to my custom midpipes just in front of the rear diff. Resonance is gone, even at the lowest of rpms. Sounds like it is alot less restrictive by ear, the pipes are bigger and the bends aren't crimped down. And it appears like it will last forever and it bolted right up to the car's exhaust hangers in the back. I'm not sure why more of the L98 guys on a budged dont't look into buying a used LT1 catback. |
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Posted on: 2009/4/10 13:36
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´89 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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| dan0617 | Re: Post of the day | ||
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Senior Guru
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Have to agree here too, if anyone is looking for a performance mod and has these gears, start here. 3.07's do good with a high stall converter but I know I'd rather have 3.45's or 3.54's. I wonder how long it would take a high stall converter to burn up trying to bandaid the 2.59's. It would be slipping alot all the time! I went from 2.59's and stock converter to 3.07's and a 2800 stall (bought both used) and this was the best bang for the buck (besides nitrous) that I did to my car. |
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Posted on: 2009/4/10 13:39
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´89 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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| mseven | Re: Post of the day | ||
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Senior Guru
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you mean the ecm can't compensate all on it's own ? If you have a maf car they are more forgiving to mods and then "you probably don't need a tune"........lol |
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Posted on: 2009/4/10 13:47
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