I drove in to Dynosport this morning to get some dyno runs in to establish my base hp and torque. When I got there this young husky shy kid was there and I intro'd myself and told him Dan had said come on in to get a dyno on my car. He said yeah I'm Dan. I thought uh oh I suddenly have doubts about all this.

He moving slowly got everything ready and asked me to back the car in to get hooked up. What the hell, I had heard this kid knew what he's doing. So I did.

after it is all hooked up he asked me if I wanted to drive and I said "are you sure?" Yeah go ahead, says he. He tells me how to do it and we run up to 30mph and then floor it to the red line. I'm worried about blowing my car up, are you sure those straps are going to hold it? He is smiling at me and says, don't worry your baby is going to be ok.

First run was a mess 184 hp I think. AFR all over the place. You are not hitting it hard enough he says, put your foot through the fire wall. 2nd run better 3rd run I am not going over 5K rpms. He says run her up to 5500 she's just warming up.

4th 5th and 6th runs I'm beating baby like a rented mule, come on you bitch faster! Those are the runs that I am showing here. Best run was 199.3 hp at 4400 rpm and 289 tq at 3000 rpm.

By now some other young guys had come in to look at the antique engine and geezer guy who owned it. Nice kids all running LS stuff between 5 and 600 hp. Lingenfelter GTO and a firebird. Dan said most of his work is Mustangs and LS stuff. It's nice to know that the Ford Chevy wars are still going strong. Here are the pics.

















Now maybe some of you guys can tell me how this is for a stock engine. No frisbee and no AIR system and an air pump delete. Next will be runs with headers 3 inch cats and x pipe installed to see what, if any gains we will make.

From my persepctive, that looks like one strong stock L98. 199rwhp is about 250 at the crank (with an auto). Not shabby at all.

Are you doing a full cat back, then? meaning, 2 cats and all?

I am betting you will pick up some power, but not a lot. The power will come once the intake is replaced; HOWEVER, you will see a HUGE jump when that happens.

One of the kids watching the runs said later that he had an IROC Camaro with the same engine and when he went to the big intake & tubes it really jumped.

This is how far the money went this year. TPiS headers, two magna flow 3" cats then reduce down into a 2.5 inch X pipe and then 2.5 inch out to hook up to the existing mufflers. Brad (jonszr1) who has tried all kinds of different combinations said that for the money this should work well. He also said that he knows guys that have done this and they really like the sound the cars make.

Next year hopefully we can do the top end. I plan on going to the dyno after each change and recording the results.

Looks like you're right at factory specs with a 21 year old engine, pretty cool. The first mod I did to mine was the pre-cat eliminator y-pipe keeping the main cat. No #'s, but a big SOTP improvement. Good luck.

Like Bogus said, Marcus, I think that is one stout stock L98. 200 hp isn't bad for that era of car.

Conditions were good, there was no correction factor. 65 degrees. I forgot to mention that the whole session cost 50 bucks.

you hsvr s good base to work from . what i suggested to ultraman (marcus ) to start with headers some good high flow cats a 21/2 in x pipe to the stk mufflers and see how he liked the sound and power . we emailed bacvk and forth a bunch for a while . we thought we would try an aproach that would be very cost effective . we know the exhaust to the x pipe will be good and the cost not bad he can change mufflers at a later date . he will now have a true dual exhaust. the narrow 21/2 in xpipe is only about 85 from summit . i dont know what he paid for the headers or cats . but even if he wants some different mufflers later he can get some really decent ones for around 250-300 used. compared to buying a corsa cat back setup for 1100or so . what i found in my exhuast quest on my zr1s was to get the pipe sizing correct for me was 23/4 all the way back . the other interesting thing was i tried the following mufflers to the same system stk zr1 409.9 borla 21/2in 413.6 sdyno max super turbo 21/2 in 417.5 and 3 in super turbo dual exits 416.5 . my muffler guy muffler man in placenta shared with me that the mufflers are so far back in the system i wouldnt see 8 hp diff between worst to best. the key to the system is to not go overboard (in my case 3 in ) as alot of guys do and lose a ton of low end tq. thats why we stayed with a 21/2 in set up for marcus as his end result with all his mods done was to leave the stk heads and cam in the motor and just get a better intake and exhaust setup. . if i had to guess i would say he might make between 20-25 rwhp with the headers cats and xpipe . i could be wrong but i can hardley wait to hear the results . bottem line he is on a budget with daughters wedding this year so we tried to maximize his dollar out put . marcus let me know how it turns out . i was glad to help such a nice guy. you are a credit to this forum .which i like more and more , most here are very classy and share openly without all the clicks that are else where . just a bunch of vet lovers sharing .jmho

you lucky guy out here in sunshine land it a 100 min for 2-3 pulls

Thanks Brad! 825.00 for the headers and 95 each for the cats. My exhaust guy thinks if I put on the headers he can do the rest for around 200 to 250. We'll see. If that is true then the whole set up will be around 1200.00

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The downside is we got winter!

and to think if one looks at a new corsa or b an b system its 1000min and no headers or high flow cats . putting the headers on isnt bad . it getting off the factory heat sheilds without looking like your hands went thru a sushi bar. i will defer to the l98 guys for any tricks they have for doing the headers as all my experience on c4s is with my zr1s . do your muffler guy like the aproach we are taking building your system ??/ . what did the tpis guys say you would have to do to get the headers on?

Quote: thats true you can keep that white stuff out there . old adage white stuff make corvette turn into a top quickly .

I did not do the original tpis header install, but I did take them off and put them back on, from underneath, not bad at all. The steering shaft was tight but worked out O.K. Like the fact that the A/C bracket and alternator bracket fit nicely. Spark plug access is real good. I have the tpis Y-pipe. It sounds like you are going to mount your cats directly to the end of the header. The header outlet is pretty close to the trans pan.

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might consider a couple of heat shields . he could most likely mount them to a couple of trans pan bolts . should be pretty easy to make

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Winter is no problem, that's when we bring out our "other Corvette"!

Thanks Joe! Great pics! We will be having to make it up as we go along. There was a thread not to long ago about heat shielding (was that by you, I can't remember). I will take some pictures along the way.

Marcus -

Those numbers are good...right in line with what your motor should be. Plus it's awesome to have a baseline to compare your mods to. $50 is cheeeeeeeeeap.

Matthew

I want to be clear - the exhaust upgrade is a winner in my book!

The L98 has two restrictions - the intake and the exhaust! Since you are fixing one or other, who cares? Besides, you are putting on a really nice setup that will support much more engine down the road. Great way to do it, if you ask me!

Similar mind set: When I replaced my OEM radiator, I went with a DeWitts all aluminum. I now know I have enough radiator to handle most any engine I put in that car.

gosh i dont want anyone to think i was knocking them in any way. i am totally just guessing since its not a zr1. on my zr1 the headers and exhaust were good for 35 rwhp. there may not be very much improvement till the intake is done ,but i am not an l98 person to really know what the actual improvement is .

you were right to make the recommendation. The thing with the L98 is that it is a 2 part upgrade... the intakes SUCK on these engines, and they need love, too.

The thing is, a cheap used upgrade may be available, too.

A good friend of mine came over this afternoon and we tore out the old exhaust system back to the cat back. We got the drivers side manifold off in a few minutes and then we had to go do the other side. It took us about 2 hours to get that bitch off. Nothing easy on that side.

What sensors are on the back of the engine by the disty? Could those be leaking oil or the disty itself? There is oil coming from somewhere up there we just can't figure out where. It is not horrible but it's steady. Thanks

Those are the oil pressure sensors... Check the connectors for oil, if so, replace! The mounting boss can leak too!

I suppose I need to pull the disty to get at all of that?

I don't know if the L98 has the same propensity for leaks from the intake as the LTx, but might be worth a look. I found that some bolts on both the front and back of my intake weren't torqued properly, and tightening them up cured some oil seepage.

marcus , what bogus is talking about is if you pull the water tight connector and look at the connector if you see oil on it then the sensor is leaking .its a common problem on the lt5 . also you might break out the tq wrench and ck your intake bolts . also bogus had a great idea on looking for your intake parts on one of the forums or ebay and buy used . there are guys allways going to the next level and you could save alot of bucks going that way. did you guys get your knuckles cut up too badly on the heat shielding????

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I think I heard of someone who has done it without pulling it...but it's extremely tight. On my car, the distributor almost touches the sensor...maybe a few millimeters clearance. There's no way I could get it out w/o pulling the dizzy. So if I had to do the job out it would come. It only takes me a few minutes to pull the dizzy and put it back in. You should buy a distributor wrench for $5 at the parts store if you don't already have one.

As far as leaks...haha, it's a sbc...could be intake manifold gaskets, vc gaskets, rear main, oil sensor...

Matthew

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Naa, I wore mittens. Took about 2 hours to get them off but my hands are great! I actually did not remove the shielding on the tight side and after we dropped the starter it came out the bottom all intact. I have an air impact wrench and that made short work of the Y pipe and cat.

Thanks so much for all you guys help. I feel a lot more confident knowing I have some back up. I will tighten everything up and check the sensors. Next year when I go into the top side we can fix a lot of things.

Keep an eye out for me on intake parts I do ok on ebay but not to good on craigs list. I like the TPiS stuff.

wiil do . glad your hands are intact

Not bad for a stock car at all. With some minor tweaks and a good tune you should be able to put down another 30-40 RWHP. When my car was bone stock it made 230 RWHP on a dynojet. After doing the headers, exhaust, the free mods, 1.6 rockers, and spending an eternity on a dyno tune, it made 275 RWHP and ran high 12's at 106.