Ok this is my first post here. i want to make some significant Horsepower mods on my 86 C4 i have the L-98 with aluminum Heads.

I don't really want to go supercharger or turbos, and im not afraid of head swaps or cam upgrades. i'm just curious if anyone has a parts list of good parts that provide good numbers for this engine.

Basicly i wanna see stuff that has been proven to work b4 i buy anything. Thanks I hope for some good feedback.

 

get some headers and roller rockers

 

forgot to ask...what gears are you running ?

 

Some excellent mods you could do is a 383 build or a 406 with ported heads,cam and full exhaust.Even if you keep the TPI,which is the main reason the car doesnt make alot of HP,adding cubes will make the car an animal on the street.It would be a serious Tq monster.

Of course I dont suggest the TPI on a larger cube motor but it still works until you upgrade it, and makes alot of torque where the engine spends most of it times on the street.You can always add the SR ,or other intake of your choice later,as the budget allows.

Some of the best,somewhat economical L98 engine mods Ive seen were a 383 built engine with LPE type cam,Ported heads,Super Ram style intake,and full exhaust.(not very cheap,but depends on where you get the parts from,and if some are new/or used)

This is a proven and tried engine combo.However,I hear the SR is a bit hard to find these days.

If you must keep it a 350,add a good cam,ported head and find a new intake system to go with the exhaust.The TPI will not let it make the TQ/HP youre looking for,but still works until you upgrade the intake end.

 

What are your HP goals and budget?
Do you wand to do a cam/heads combo or just bolt ons?
Is it going to be a DD?

The options are endless and you are going to get allot of different opinions on this.
you are also going to get the TPI sux lecture..

 

Im not sure at the moment ill have look it up and post it later

Thanks for the replys, for HP Goals i like to get at least 300+, and for budget i can spare 2-3k witch i think could get me some decent parts and HP.

 

Ck out vader's website

http://temp.corvetteforum.net/c4/vader86/

and ck this out good info on cams
http://www.z28.com/forum/showthread.php?t=79261

Hre is a good thread on a 300HP l98
http://forums.corvetteforum.com/c4-t...00-hp-l98.html


Also are we talking 300rwhp or 300chp?

 

you should seriously look at the hp GMPP vortec heads. they are inexpensive, they are not detonation sensitive, and with your dished pistons, have them machined down to 60cc, put better springs in em, and put your money in rockers, intake, cam, headers, and 2 sets of mufflers. after all, the first set that you buy is going to have so much resonance that you will have to change them out.

 

That is where im at right now, these flows are killing me.

I have been thinking about getting one of these Patriot auger style inserts and tacking it in just behind the cat before the y pipe.
http://www.summitracing.com/parts/PTE-H3843/

 

Thanks, these did help with some questions i had, 300rwhp would be what i want more. Im gonna make a list of parts i was thinking of 2night and ask for some opinions on my choices b4 i buy.

 

I had the same questions and goals and found those usefull. The guys around hare are awesome!
Heres what I did:
I would have gone with the vortec heads if but ran out of money.
My next mods will be 2400 converter 3.45 gear and LT runners.

1991 TPI stock long block 113 heads
Old style SLP runners gasket matched with Bigmouth intake gaskets.
TPIS Bigmouth intake
Ported plenum with 48mm TB
CC502 cam 218/224 @.050/495/503 lift 112lsa
Bosch III 24# injectors and AFPR
Scorpion 1.5 roller rockers
Flow master cat back and TPIS Ypipe
I also ported the stock shorties gave me another 3/8 inch in diameter

I can post a video of the loap if you want.

 

did you just port match it basicly then? the shorties

 

We have sister cars all though mine is a iron head.

My experience is;
-that you must go with a good cat-back.
-a Magnaflo cat is better than a test tube.
-the pre-cats can be removed without messing up the environment.
-a cam is a must (CompCam 260XE) if your not going to fool with the heads.
-and a tune from PCMforless is a requirement no matter what your planning.

 

They are welded on the inside (the bead is thick) and the air tubes go in like 1/2 inch.
I smoothed out the welds and grinded the air tubes flush.

 

i was just looking at my stock manifolds and thought "Maybe I should grind down where those air tube go into the pipe so far" Damn, it's all back together.

 

Ok its been awhile since i started this but heres were im at and i had a few new questions.

So i decided to budget 1.5k -2k for my mild build and so far im on track.
Heres what i got so far.

Ported out Plenum
Edlebrock Intake and Runners
52mm TB
Smog Pump Removed
Upsized fuel injectors
adjustable fuel regulator

i know from the treads iv been reading the Mini Ram is the way to go, but i got some good buys on all this (1.2k for that so far) and im going to stick with this plan at the moment. I still have my top end taken apart and now im ready for some more parts.

Questions.

ok for Roller Rockers, how do i tell if they will fit under my Stock Valve Covers? i wanna get a 1.6 ratio set with new spings. So if someone knows of a good set or how to get the sizing to fit plz tell.

For Headers i have a good price on Ceramic coated long tube Headman headers. Any opinions? I have heard good and bad on other treads. Or sould i get some shorties? Havent heard too much pluses by going that way.

Distibutor? Is there a good upgrade that will fit under that little cover at the back of the plenum? is a upgrade needed? or other options? i only want the cover cause im kinda trying to keep a stock/certain look.


I did want to go all the way at first (heads, Cam crank, maybe)but didn't want to pull my engine (yet) and diecided to just go mild and dress up my engine. If and when i do pull it id probable do a pretty big build, stroker/something more, new.

 

The 52 MM throttle body probably wont hurt but it wont do much for you. I'd sell or trade it for a cam. You can do the cam without even jacking the motor up in an 86 and the cam will do more for you.

 

Cam,rockers,springs,AFPR, headers, your intake plans, and a custom tune, will keep you content until you build your monster.
The TB, injectors and distributor money, can go towards the beer bill.

 

hmm i have been wondering about if the cam could be changed while the engine is in place. Does the radiator need to be removed? If thats all that has to move i think i may be investing in a cam also. I would like to see some pics of this, i was thinking of checking my timing chain anyway

I think i'll hang on to the 52mm for now tho i had seen that some guy who sells a 54mm but decided the 52 would be fine for my goals.

But if the stock HEI distibutor is adequate enough i could just freshen up my old one (it could use it) and use that money saved for a cam.

 

1. Add an MSD 6al box to upgrade the ignition in addition to a high energy ignition coil.
2. use bosch platinum plus 4 spark plug.
3. Use ignition wires that have less than 100 ohms per foot.
4. Use a distributor that has brass terminals, not aluminum.
5. reground the engine to the body
6. then use another heavy wire to the negative battery connection to the frame.
7. larger throttle body 52mm, and dual cats and dual exhaust.
8. Use the cam out of the HT383 Chevy Crate engine (same as the ramjet cam)
9. drop your tire size to 245/50/16 if you want to keep the stock wheels
10. use a high flow fuel pump with an adjustable pressure regulator, and a fresh fuel filter every year.
11. use a fresh paper filter every year or a K&N
12. change the rear end to a 3.07
13. pocket port your own heads
14. use 1.6 roller rockers
15. buy Bosch III injectors
16. have your exhaust manifolds welded on the outside, and grind out the inside welds
If you get this far on the car, it will definitely have a more agressive personality, and you will need new bigger brakes.