Thanks guys. I usually post in the RR section but C4 Tech is still what I consider "home". I couldn't have built this car without this section of the Forum. I'll post more of my race stuff over here if anyone is interested. Sorry for the brief Hijack but here's some info for the OP. What works?? L98 mods that have and are working for me:

El Cheapo 350 2 bolt main short block from Pace performance (L98 replacement) $894 to my door w/ a 12 month, 12k mile warranty.

TPIS ported 113 heads- $1250 10:1 CR

TPIS big mouth base w/ Accel runners (ported by me)

Hot Cam w/ 1.6/1.65 RR's

Hooker 1.75" long tubes w/ 3" exhaust and X-pipe

24lb Ford Injectors w/ a Stock tune. The computer hasn't been touched. (MAF cars rule)

Nice idle, 320+RWHP/ 400+RWTQ. I need to dyno it again because I couldn't adjust my fuel PSI before. Plus I don't run mufflers anymore. My best guess is 330/410. If I get the diff back in I may try and get it on the roller next week.


See above + VBP Extreme springs, 32 Hollow front, 26 rear, revalved Bilsteins $225/set) LW hood, lexan windows. My class has me run ~3100 lbs w/ me in the car but the car is as light as 2750 lbs w/ 1/2 tank.[

 

Wow, it didn't sound loud enough to be straight pipes. How much resonance and how loud is it? Is the video representative?

I thought you were running 47/50PSI last year. How'd you do that w/o an AFPR?

Is this the first or second rear-end you've smoked? What "goes out" when that happens? Gears, seals, or something else?

With your weight/HP limit, it's obvious to see how and low-hp, high-tq TPI setup can have it's adantages. What rpms are you running in the race? How high do you run it up before shifting? When you downshift, what rpms are you looking to stay above (if any)?

BTW: You should tell people which car(s) are in your class in the video.

 

Thanks for sharing the video Matt!!

Your car sure sounds great without the mufflers. Thanks now I know what my car would sound like.

Good video for all the TPI haters out there, sure sounds like you were still pulling hard all the way to 6k.

 

The 3/4 scale red Nascar w/ a 1300 cc Hyabusa engine that weighs 1500 lbs. , a C6 that is behind me and 3 other C4's that are also behind me. They're actually in a class higher than me but I like being the first C4 if I can.

 

Your welcome. It will run to 6000 if I have to. I'm a little over that at the end of the straight away before the keyhole. 120 mph in 4th. 3.45 and short 24.6" tires. That's another thing that makes it ruff in the lower class is that I have to run 285's on all 4 corners at my weight. It would be nice to slap on 315's......Oh well.

TPI haters... Yeah, the forum experts at the time swore that my car would never run w/ an LT1, let alone C5 Z's.

 

supercharge it .. I have an 85 vette with an intercooled vortech at 8 psi boost
extra fuel pump and extractors adjustable fuel pressure regulator.
changed quarter mile from 13.7 sec to 11.9
you have the drivability and tourque from idle with massive mid range and top end grunt
Has been on car for 3 years and running standard computer chip and mass airflow sensor after intercooler and has great milage with a smooth idle .
cheap power for the money
:P

 

MBDiagMan, I have just been reading thru these posts and you seem to know your stuff. With that, and the fact that is is from sometime ago, I am currently having a 350 built for my 1987 Corvette. The block somehow cracked on me in the L98 so necessated a new motor. Here is what I have done so far, keep in mind I haven't changed my intake manifold, runner's or plenum as they are coming from my original 170,000 mile car. What has been done to these 3 items is machined, cleaned, repainted. Also using the original heads but also, machined, cleaned and all new internal's as you will see.

Using Summit Racing parts I am building a new motor for my 1987 Corvette. Motor 350 bored to 355. Double Roller Rocker Timing Chain and Gears, Flat Tapet Pistons 10.5 compression, Flat Tapet Valves, all hydraulic. CompCams Hydraulic Flat Tappet, CCA-12-239-3. Machined and Honed L98 Heads using 1.6 Stainless Roller Rockers, new valves, guides, and springs. Summit Racing Chrome Valve Covers. Machined and Honed Runner's and Plenum. (I may be mistaken about saying "honed" but the machine shop did a hell of a great job on all.) The Cam specs are: Comp Cams: 218/226 .462/. 480 111 and- Basic Operating RPM Range 1,300-5,600. I also have a new GForce Computer Chip installed to match the new setup as the original chip as we know would not work on this cam. As to the exhaust I have a pair of shorty Sanderson Header's, NO Pre-Cats, hollowed out main Cat, straight thru with only Baffled Chrome Tips.

What are you thoughts on this setup? I would be interested in knowing. Thank you.

 

Sounds like it should run well but youll need those cats on to smog it they are really tightening up on the sniffer in ca..and the visual.

Didnt catch it did you get your tune (chip) redone to accomodate the mods?

 

The factory 3:07 is sufficient and a stock TC. You'll have plenty of torque so the TC will only be valuable at the track.

 

Awesome video Matt!! I shared it with my 8 year old and his friend, they thought your car was "the coolest ever".

 

Interesting reading if you haven't already seen it.
You will have to log in to see the pictures though (register).

http://www.thirdgen.org/techboard/tp...-manifold.html

 

Yes, I had on the original L98 a "Gorilla Chip" then on this new motor used a HyperTech ThermoMaster Chip I bought like 5 yrs ago. I had ordered a GForce Chip, which installed, created lots of problems besides not starting. All this after I had the chip built to the new engine specs w/cam. Now I am back to the HyperTech Chip and it won't start. Seems to be way to rich and fouling new sets of plugs.

 

TPI haters... Yeah, the forum experts at the time swore that my car would never run w/ an LT1, let alone C5 Z's. [/QUOTE]

I don't know how I missed this thread back then, but I like it.

 

I don't know how I missed this thread back then, but I like it.[/QUOTE]
I agree. Dyno Don over at third gen, and a few others, are making 400hp or more to the rear wheels, and passing smog with their TPIs. You just can't match the look of a TPI. I guess you just gotta have the will and skill.

 

you have to be dedicated to the L98/C4 combo to keep trying. I gave up. It takes too much time.
I put a 383 in my 86 and too loose of a converter. it acts like it slips at lower RPMs and I get tremendous power when i shift out of overdrive (700R4) to third, 2600 RPMs, 70 mph, but it doesn't last much longer than 4700RPMs. By then I'm doin 127 and shift to overdrive.
The car is 25 years old, and needs new bushings. it's scary when it shifts.
I decided that was the last time for me to do that when I did it the last time...... even with new bushings.

 

Yes, I had GForce do a chip for me with no results when installed. Now I am having my factory Memcal being reprogramed with all of my engine specs. While I went back to the HyperTech Chip which was running fine until I attempted to install the GForce Chip. What I am seeing in my research is that I really should probably change the intake, runner's & plenum to a setup that will work better for an engine estimated at approx. 350 hp as the stock units won't handle anything in the 350 hp range or higher.

 

No mystery it's basically a 350 SB Chevy of old small chamber fuelie heads with dish pistons.flat tops and mild cam 220-230 duration factory 350/350 was 222.premium fuel with flat top Pistons

 

Last post in this thread was 10 years ago and Quinny has not posted since 2009.. Just sayin'.

 

Thanks, may have to check this out.

 

Just something I want to throw out there. 1986 auto Vettes have the best stall converters numbers.. wise. Cant find a new one? T he S10, 4 wheel drive converter is the same. Good info here.