please bare with me as I learn, Im ASE certified so I do have the knowledge, but im just a parts changer.

I wanting to get the most out of my 91 l98 with out pulling it. so I want to stay out of the motor as much as I can, I plan to build a motor in the future but until than more performance is good.

this is what Im thinking.
1.6 roller rockers.
tpis miniram and 52mm TB
headman LT headers
true duels, no cats (no "save the earth" commets please) , H pipe, magnaflow SS mufflers
chip made by tpichips or maybe tpis.
and other minor things k&n, adj fuel reg, etc
after that Im out of money.

how well do you think this will be? the motor is newly rebuilt about 20k ago, I dont want to pull it yet, since I dont have the money to build it the way I want. And its a daily driver, less down time the better.
thanks
thanks

 

my opinion:
lets start by saving you some money.
for now skip the 52mm TB, 1.6 rockers and the headers. you can do them later on when cash permits.

go with a used (hopefully good) miniram if you have a 6spd or a superram if its an automatic, and reuse your stock TB. add an adjustable fuel pressure regulator (if it doesn't have one already).

now buy a set of head gaskets and pull those stock heads (its not that much more work once the intake is off anyway). take them to a porter and get a decent cleanup/port job.
it will do way more than 1.6 rockers could hope to do.

run true duals off the stock exhaust manifolds (for now anyway, later you can add headers and hopefully tie into the duals).

also look into doing your own tuning, you can buy all the stuff to do it for under $400 nowadays (except the laptop). if your sure thats not for you then find someone close by who will do a custom tune "in person on your car", preferably with a wideband O2 (or dyno with wideband).


all that will be as good as or better than the original plan, plus when you add the 52mm TB, 1.6 rockers and headers you'll get even more power, plus they are easy to do later.

thats my 2 cents
RJ

 

without upgrading the internals I would guess:
rockers-5HP
miniram-10HP
52mm-zero.
headers-10HP
Free flow exhaust-10HP(go x pipe not h)
Everything else you mention=zero.

 

As above

"since I dont have the money to build it the way I want."

For the price of the MR you could get far better results on other mods if you aren't prepared to change the cam.

 

I had a similarly modded '90 6speed, but I was running a ported TPI plenum with a big mouth base and TPIS runners. It made 277rwhp and 365rwtq and ran 13.02 @ 108mph in the 1/4. I suspect you would see similar or better results with the miniram. You don't need a bigger throttle body on a stock cube L98 though. I still have the Stage 2 TPIS chip from that car, which would probably work great for what you are doing.

 

I would do the 1.6 rockers, especially if you aren't changing the cam right now.

Miniram won't give you alot without changing the heads/cam. Go with it if you are going to be revving high on the new motor down the road, but an aftermarket large runner TPI or tons of porting is better suited to the stock heads/cam in my opinion.

Headers and duals are a big gain on an L98. Was the first thing I did to mine and I loved it. If I did it again it would be the 3rd thing I'd do. Torque converter and shift improver kit would be the first 2 things. 2200 or 2400 stall with TPI or 2800 on a non-daily-driven car with superram or miniram.

I had a custom dual exhaust tie into my factory cat back system since the factory cat back was fine. I like it and it saved me $$$

Pcmforless.com for the chip, talk to Alvin. That is for a good inexpensive easy to do chip (just order it and let Alvin do the work). I think more can be had from tuning yourself but there is a learning curve. You don't need the afpr, K+N or 52mm throttle body, they won't do anything.

Seriously, converter, shift kit, external tranny cooler, headers, duals back to the factory catback if it is in good shape, 1.6 full roller rockers, pcmforless tune, port and polish or replace the TPI, port and polish or replace the heads, depending on how deep you want to go.

IF you are on that tight of a budget, I'd port the plenum and base, buy used AS+M runners. Remove and port the heads, have them shaved and use a headgasket to take you to about 10.25:1 compression.

 

thanks guys. I was only going to run the 52mm tb b/c my factory one is sticking, Ive cleaned it and replaced the spring and it still sticks open. and if I need to replace it Im going to replace it with a lager one sice their about the same price as a remain one.

so is TPIS just full of ****? they clam that with the stock l98 heads and cam flow around the same as an lt1, and they say that with the miniram you would get about the same numbers as a lt1?
it seems like noone makes any good preformance parts for the tpi. everything ive seen is way over priced and has very little gains. ie: intake and runners from edelbrock, around $1000 and you will get maybe 25hp if your lucky..
Why is the TPI so week?

I think for the money I will just go with a standalone FI kit or just buy a used lt or ls motor

what do you guys think of the procharger supercharger for the tpi?

 

Now youre talking, best hp for the buck.

 

Funny how things work. Jonescap and I have near identical cars now. I also had a similar 90 model/modded 6 speed.


IMO, as a former ASE GM wrench turner and vette owner.

Do go with the 1.6 RR

No need for AFPR (my dyno before after made no difference )

Go ahead and do the KN. It wont help much if any but makes us all feel better and they never wear out.

I picked up a solid 20rwhp from going to true 2.5" duals, no cats with an H pipe over the stock system. Verified with before/after dyno results. No loss of low end torque either. (I did have intake mods and such prior to the exhaust)

Go with a set of long tube headers when you do exhaust.

Nothing wrong with the miniram or superam, they're just e$pen$ive.

As for intake. I'd recommend using a modified LT1 intake. Your heads(113s) are not that much different from the LT1 castings. (waterflow excepted). Several people here with alot more mods have done the swap from the superam/large tube runner setups to the LT1 intake setup and were surprised to see no loss of low end torque and in many instances they even gained. What this will do is extend your power band several hundred RPM. Its a heck of alot cheaper than a miniram setup. In all fairness though its a swap that takes some figuring out. If you're an automatic plan on doing a bit of engineering to make the cables work and what not but it can be done.





heres some reading......

http://forums.corvetteforum.com/show...ied+lt1+intake

http://www.lt1intake.com/files/swapping.htm

 

interesting Ive got some researching to do. thanks man

 

The LT1 conversion is what I was going to do, but I ended up purchasing (haven't received it yet) a Holley Stealth Ram with custom made Vette plenum and smallcap distributor. I also ended up with 113 aluminum heads ported, polished, and 2.02/1.60 valves. And a CC503 cam. Supercharge if you can. I'd still swap intakes, and you are going to need to replace the headgaskets because the stock ones won't hold up long to a supercharger. You can play a little with gasket thickness to get the optimum compression ratio for boost. Port the heads while they were off, but if supercharging I don't see the need for bigger valves and probably not even a cam swap. Sure you could get a little more by doing those, but why spend the time/money when you can just crank up the boost. I'm not sure how long your stock bottom end will hold up, but you can see the mods I'm doing to mine and I'm also running a 100 shot of nitrous, so I don't know how long my stock bottom end is going to last either

 

The TPI system on these cars was originally designed for the 305 motor because GM was going to drop the 350.When they decided not to they used the 305 system instead of upgrading it.That's why it dies above 4800.Go take a look on the firebird/camaro website www.thirdgen.org where you will find plenty of modified intakes at more reasonable prices than the vette guy's ask.Whatever you decide you won't see huge gains without changing your cam unless you go forced induction.

 

Hold off on the Miniram until you do a cam.
Do the 1.6 full RR's with LT4 springs
Do the Hedman Elites and true duals
Port the heads to the max
Port the plenum and runners to the max
Do the 52mm TB if yours is shot

You can wait on the chip but it will run better with a PCM4less tune

 

has anyone everdone the lt1 convertion? or anyone have any input about the guy that mods the intakes?

 

Good minds think alike