John A. Marker

I don't want to start a P***ing match over tune vs non-tune. I would agree that if you changed injectors, you should have the car tuned. And by changing injectors I mean going to a higher flow than what the car came with. Many of the posters suggested gong to the 383 base. I would think that with this large change is displacement that a tune would be required.

I consulted my tuner when I first started to play with the old L98. I was able to change from the cast iron heads to AFR 180, added the split 1.5 & 1.6 roller rockers and the complete SuperRam setup (intake manifold, runers and plenum) without the need of a tune. I also changed injectors because of the mileage, but stayed with the stock 24 pound that the 85 came with. Would the car in this configuration have run better with a tune? Yes it would to fine tune all the parameters. I ran the car for over 9 months this way before I could get it in for the tune. Did the tune drop 25-50 more horses to the wheels...no. Did the car run better, yes. Did I get a SOTP feel for more HP...no. The point is that your stock chip can and will handle may changes before you have to change it.

When I built the ZZ4 I moved over the heads, SuperRam and added the Lingenfelter 74211 cam. The chip had to be redone, since the old chip would not handle the cam swap. My compression stayed about the same, intake and heads were the same and the chip that ran it before would not handle the major change of the cam.

If you also read what Vader86 has to say, you are not going to get much out of the bottom end without a cam change. Up graded parts and paying attention to the little details on assembly (such as balancing) will yield minor gains. It does not sound like the OP is looking for large HP gains since he talks about timing chain and oil pump.....then mentions performance modifications. It has been said before that performance cost money. How much horsepower do you want = how much money do you want or have to spend. His limiting factor of not wanting to change the chip limits his options as Vader86 and myself have suggested.

JrRifleCoach

The factory cam is NOT Corvette material.

The chip can be enhanced to extract the extra power.

A Corsa cat-back is a must.

GREGGPENN

In reality, you may not want to swap intakes w/o a chip change/tune. I learned to do the tuning on my 89 MAF car. So, I've at least had some personal exposure to the elements inside a tuning map. Though a SD car is different, the main consideration is whether fueling or timing needs to be altered. (After all, the ECM is doing what the old carb/mechanical advance systems used to do -- only better.)

On MAF cars, the Power Enrichement (PE) curve is loaded into into its own table. It's purpose is to increase fuel supply where VE goes up. VE is a measure of how efficiently the motor is receiving air. With a longtube intake, it goes up and peaks much sooner than a shorter runnered motor. So, if you swapped intakes w/o changing the PE table, you'd be running rich/lean during rpms where the new intakes VE characteristics did not match the old intake. MAF tunes for a SR don't have the same PE as longtube intakes. That's my experience anyway.

Since I've not yet studied the details of SD cars, it would be interesting to know if this is true for SD tunes as well. IIRC, SD tunes are based on VE changes, so maybe they are more flexible in this regard than MAFs?

BTW: My point is to show what you're "tinkering with" when you toy with the idea of performance mods w/o wanting to tune the result. By contrast, it's not really hard to get a tune for the types of 383 (more aggressive) builds suggested. IOW, don't settle for a timing chain and oil pump if you really want to improve performance. Just factor in the tune cost.

mseven

IMO, depending on what someone considers "small changes" and if then needing a tune or not, can only be answered with data as real evidence. ..everything else is really just speculation.

Today most have a laptop and Data Master is still free for 20 runs.
After doing whatever changes why not get an understanding of what the car is doing, as the cost would be a cable ?

8388

How about this. Back in 1991 I swapped out the 305 that came with my 91Pontiac GTA with a 383. This 383 had a moderate cam profile to work with the Mini Ram, 30 lbs. injectors and headers. The perfect tune turned out to be the factory 305 chip along with some minor adjustment on the fuel pressure.

On street tires the car ran mid 11's @ 119 mph in the 1/4.

RLDaily

An engine is nothing more than a glorified air pump, so how much air do you want to move and how much are you willing to spend?

What do you want to do with the car? I love my stock L98, I push on the pedal and she goes.

Yeah, lots of horses are cool and I love 'em (I'm an old 60's-70's muscle car guy myself), but do you really need them? My old 1968 AMX pumped out about 615hp (verified by RHS in Memphis way back when) but I couldn't really turn it loose on the streets...I did run 10.02's though

Good luck

8388

Today, if you're not putting down at least 800 to the wheels you're not real competition. 1000-1200 whp is now the new number to shoot for, and I've seen plenty of 1100-1200 whp playing on the streets, it's not that uncommon anymore.

GREGGPENN

Wow, that's pretty close to what the OP was looking for!

SkipRiggs

Thanks for all the great advice, I'm going to stick with a stock rebuild with minor upgrades. The best part is that I've got a great shopping list to go by, and I'm going to take my time with a 383 build. This is possible because I have two engines. One will be mild and the other one wild. I've been reading your responses at least twice a day and really getting excited aver the two projects. Again, thanks a million.
Skip 90 Vette L98, 91 Vette ZR-1

John A. Marker

Before you start your build, read Vader86's web site. If you go back to page one and click on his name, his web site link is there. You will find a lot of information....good reading.

cv67

Unfortunatley the money to do that is uncommon these days.

redvetttes

I agree
What works and what doesn't

8388

I wasn't responding to the OP quest for "engine upgrades" but rather to the post about too much power for the street.

rick50

I have a stock 1990 L98, if I wanted to change the cam for more performance what else do I have to upgrade?? I'm reading that the chip has to be upgraded - mine has a hypertech chip already, I dont want to spend too much money but I love the sound of a cammed up motor, any help would be appreciated.

Rick

John A. Marker

Rick50, your chip will not do you any good if you change the cam. You need to go to a good tuner and have a dyno tune and a new chip made matched up to your modifications.

engle1147

A "Hypertech" chip is not a real tune. A generic mail order '90 TPI "tune" will run about $200 and up. Shop around for what parts and labor(if needed) cost are before you jump in. Do some research - do some "free mods" then move up to buying some DYI bolt-on mods and and go from there......leave the cam/heads alone for now.