I'm curious also. I've been considering doing the whole upper end on my '85. Heads, Cam, Superram, Headers - what kind of power is safe to make on the stock short block?

Thanks,

Ryan

 

These people sound like muscle car guys to me.

you can do heads, cam, intake and exhaust to really wake the car up.

I have a super ram, AFR 190 heads, ZZ9 cam, 1.6 roller rockers. this got me some more rpm's out of the car, but for the money spent I was not happy. I got headers with true duals and a chip from somone running a close combo. all this woke the car up big time. I would guess these mods would take a 350 short block to ~350-390 hp at the crank. I could feel about 3500 rpms the power would kick in and get things moving. I would have loved to dyno the car with stock exhaust vs the modded exhaust, but I lost a piston on it (not stock). I am now going twin turbo.

all this can be done leaving the smog pump and EGR in place.
the exhaust mods will depend on where you live and the laws that apply.

I can tell you from my research on superchargers from years ago, you do not just bolt the thing on and it is making the power advertised. more mods need to follow. one is exhaust. you need to get the exhaust out of an engine that you are pumping air into. other things like heads, cam, intake can all maximize the power it will be capable of.

with FI you will want a good tune, and a forged short block so it will be a little more forgiving if you ever run into detonation.

other things to address are a fuel system with a blower or turbo.

if you cruise over to the forced induction side you will see someone has come up with a single turbo set up that they are selling. I think you could spend a week in the FI section reading through everything and get a good idea at what we are all trying to tell you.

 

I think these guys are who carroll supercharging once was?

back in the day, carroll supercharging made some kits to mount Vortech blowers onto TPI c4's they sold the bracket alone, as well as the intake pipes needed to complete the set up. or you could get the whole set up.

Maybe they still have some of the stuff if you prefer a vortech over the procharger/paxton's

 

I can recemmend a setup on an LT1, but I'm not so sure on the L98's. I know there are quite a few guys on this forum with stock bottom end L98's that could chime in on what there set up is and what kind of power they are making. It will end up depending how much you want to do. I started a project that was just a head port and a cam. It has since snowballed into modding practically everything else over them except the bottom end. Now that everything else is done, the bottom end is the next to get $$ thrown at it, bored .30 over, forged rotating assembly. After that? Then you might as well go FI, either NOS or a blower. I swear, it's a never ending cycle.

Actually, you are better off keeping it stock and saving all your money. LOL.

 

if it were me, I would have to sit and think long and hard on what I wanted to do.. but considering all things.. you have poor heads, a torque specific made intake manifold, a small cam and a lack luster engine management system that was great in its time but is now quite finicky and requires extensive chip burning to get any combination to work properly.

that being said.. you could find a late model LT1 engine with engine harness and computer and if its from a vette even the accessory bracket.. and swap it in... this opens up some other quirks like the dash board function but I would think you could get it to work with some persistence. the other idea would be heads, cam, roller valvetrain, and swap to a superram, miniram, or lt1 intake manifold. the LT1 platform offers a good deal of imporvement over the l98 with block integrity, better rods and crank and wake up VERY well to mild street cams and some head work. 350-420 rwhp isn't uncommon with a street setup on a 350 cube motor in an lt1 with good tuning. the other option is sell the car and go to a later year if performance is what your after.. 92-95 cars have come down in price and are quite affordable while a clean 87 is pretty much staying steady in their market price. that jump alone will gain you 60 hp with no modification and a gain of about 1/2 second in the 1/4mile. just some thoughts.

Chris

 

Chris,

Thanks for the inputs, but all things considered I'll keep the car. I only paid $3500 a couple years back and have completely refurbed the suspension (all poly, heavy springs, QA1 Adjustable shocks), installed the C5 brakes, slotted rotors in front, MBP pedal mount, Richmond 6 Spd Transmission, Z51 performance beam plates, R-D racing Camber Brace, installing a new clutch now, installing a Shinoda/Mears body kit now (installing the rear bumper this weekend), eliminated the AIR/SMOG stuff, updating the exhaust to glass packs and slashcut 3" targa's (parts on the way), and machined up my own adapters for 92 Sawblades (currently installed). The motor has 1.6 rockers, ported Plenum, 52mm TB with ball bearings on the shaft, new blue top injectors, Holly AFPR, upgraded Mallory distributor, coil and Hyfire Multispark box. Installed new Cloyes timing set and new water pump.

Only has ~ 90K on the clock.

I have an LS1 crate motor ready for my '69 race car project, but I think I'll keep the Gen 1 L98 in the '85 till it blows. If the short block goes I'll go full house 383.

I keep waivering from just putting headers on the existing motor to get rid of those ugly exhaust manifolds and going all out with a top end workover.

Those Hedman HTC headers are awefully tempting for $329 at Summit!

Ryan

 

I had those headmans on my 90, IMHO they are ****. they work, but they took a beating from hanging down too low. they leaked, and caused O2 sensor problems, where the car would chug when moving from a stop. the flanges are weak and after installing and removing them a few times, I noticed they started to bend. at one point I wanted to cut the header flanges off, and have them welded to a set of stock manifold flanges.

if I were going to put those on again, I would get the non coated ones, put exhaust wrap on them, as I did on mine, and just replace them after they took a beating and started leaking. They are cheap enough at what I remember around 100+ bucks.
I had a little system going on here, that it was very possible to do this.
I just hated dragging them on everything I went over (speed bumps driveways etc). If you can install and remove them yourself, and dont mind doing it, it maybe something to consider.
My car is lowered a bit, but not close to what some of these guys have going on here. also my area has huge speed bumps that I hit when the car was 100% stock. steep driveways that for a TP shape that the bottom drags on. not much I could do.

Some guys buy vettes and drive them, other get addicted and start modding the crap out of them. for me the labor was nothing, and throwing a $100, or $150 at it every year just for headers is not really a big deal at all. I fall into the mod the crap out of them catagory after my first engine build.

 

Well, hadn't heard they were so much trouble. I have a lift so installing headers is a no brainer. My car is not that low, I actually lowered it - found is screwed up my suspension geometry for autocross and raised it back up to stock height.

I drive the heck out of my car, it is not a show car, it is not a sunday cruiser. It is nearly a dedciated track car.

Ryan

 

If you consider the headers to be a throw away part if they get destroyed, and you are willing to replace them, I say go for it.
sounds like they will last you a long time.

 

i know the car had work done to the cam when i bought it, i dont know exactly what it changed however. also, the exhuast has already been done.

one thing that was recommended to me by a shop was (forgive me if i get this wrong) shortening the rocker arms? does that make sense?

what exactly should be done to the heads?

 

its a mustang specialist company, but they claim to be making a kit for the 85-91 vettes. but they will make a kit for your car no matter what it is, it just might not be listed as a kit.

http://www.turbochargedpower.com/HP%20Turbo%20Kits.htm

 

http://forums.corvetteforum.com/show....php?t=1341859

see this post about this.

 

shortening the rockers arms? odd.
You can change the ratio's on them. most stock SBC I believe have a 1.5, or somewhere around there ratio.
1.6's will open the valve a hair more, and accelerate it slightly through it's movement.

heads? Do you have the 85 iron heads on it?
Most go to aluminum heads.
heads will help you flow the air into the engine. the best cam in the world wont do much without a good set of heads.

basically, you need to figure out a realistic HP goal, and get an intake, heads/ cam combo for that. gears may follow if you are looking for a drag racer, and change things a lot.

 

Greg Carroll is the founder of of Blowerworks in Wycoff New Jersey. I am sitting here reading his 100 page (C4 specific) catalog as I type this. On page 28 it shows the base kit for 1985 - 1991L98 models 350HP @ 5000rpm $4,995.00 My copy is from March 2005 Revision # 61.
Stage I 350 HP $4,995
Stage II 400 HP $4,995 + $1,295
Stage III 450HP $4,995 + $1,295 + $3,195


www.blowerworks.net NOT.COM
phone = 201-891-4690

It says that they make kits for L98 from 1987 onward.

 

Greg at BlowerWorks is one "super" person!
When I bought a used older setup and found his name stamped in the blower bracket and called him, he went above and beyond to help me get the old Paxton set up running. All I can say is his stuff is pure quality at it best.