Hi all. Let me introduce myself since this is basically my inaugural post. Im about 20, a computer science student, love cars and motorcycles and working on them. Got about 3 years left in school (2 undergrad, 1 masters year). I picked up a ‘93 white coupe, with the 6-speed and it has the RPO for the 3.43 gearing (i dont know if that was standard on manuals). Anyways, over the next several years i want to build this into a stout and reliable forged 355 with one of Carol’s blower kits on it. Unsure of the exact power im going for yet, since itll be pretty decently into the future. So far it already has a SS corsa cat back on it, and i replaced the headgaskets this summer and found the previous owner wasnt lying, it has also been bored to a 355 with new Hypereutectic pistons and rings in it. I also replaced the water pump, sparkplugs and wires, and used new ARP headbolts. Only about 4500 miles on all that.

Anyways. I just want to know where to start looking and what to look for. So far ive already determined i need some long tube headers, probably a good cam (what should i look for here tho. Should i look ahead for a cam thats blower ready? Is that gonna be streetable without a blower? Should i save this and buy it when i finally buy the blower kit?) i was also looking into a forged rotating assembly(this is the crank, rods, bearings, etc right?). Also probably want to port my heads before this. My stock heads were milled to level when i replaced the headgasket although i dont know how much was taken off. Would it be better to just buy better flowing heads? Im looking for around 500rwhp at the end of it all, and would like room for more later if possible (perhaps changing out the blower pulley). Any suggestions or direction would be SUPER appreciated. Also i dont mind doing some work, but i am def not equipped to bore, hone or mill any metals😹but im not opposed to buying tools when needed and getting down on my back if need be.

edit: i can find good headers on the forums easily. I should clarify im most confused on the heads, forged rotating assembly parts to get, how to compute compression, what compression im looking for, which brands have quality rep etc.

 

You dont need forged parts for a blower build at that power level.

forged parts are kind of like ‘insurance’, but if you avoid risky tunes (with too much spark advance) , have meth/water inj (and/or a good intercooler), enough fuel pump/injector, run e85, and/or lower compression. Its un necessary. People blew stuff up constantly in the old days bc they didnt understand tuning, have enough fuel/ injector, etc. and now e85 is available. The old days are long past

id check compression in each cylinder And if good, id run with what you got.

it sounds like the engines static compression may be on the high side though. You can put on heads with bigger cc chambers to drop compression a little if need be. Otherwise thats gonna limit boost

so if you have to rebuild, go forged. But dont rebuild just bc you think you have to have forged parts.

id go 383 also if you rebuild.

 

cool! Thanks for letting me know. That’s definitely takes a lot of thought out of it lol. With reliability a concern what would be the upper limit in terms of ho/tq and having a reliable DD on the stock internals.

 

500rwhp I would definitaely get forged parts...some get away with it with a perfect tune but one issue it all scatters

Why worry when youre foots in it takes all the fun out of it
id definitely just buy a better head, and yes to a blower cam.
We have a member here who is gets sweet deals on AFRs that can save you some. More power with less boost

Take your time spend the $ and do it right the first time, rarely time/money to do it over.

 

yeah this was the line of thought i was following to begin with and will likely stick to. Im a pretty cautious person and id rather have the confidence that its over built than anxiety that its under built.

also, how does one become acquainted with this AFR plug. Since my blocks already bored to a 355 what else would a shop need to do to get forged crank, rods etc in there properly. Ive read of the block needing to be decked or something to specific measurements and all that? I believe this was done by the last owner themself though so maybe worth a once over by a shop at the least?

also for tunes, i thought carol sent the proper tune chip for the car, or the software to tune it if you wanted to buy it.

 

I simply slapped AFR heads with bigger 61cc chambers to drop static compression to 9.7:1 for my forced induction build on a stock bottom end lt1.

Theres at least 509 rwhp on it (old smaller blower, and that was only at 5600 rpm - i wasnt able to test it any higher that day. It was still mKing power)

1993 stock bottom end lt1 takes plenty of boost.
Detonate once over 5000 rpm and that’ll ruin ring lands.
however if your knock system is working - you wont have that issue.

its pretty bulletproof !

even when my methanol / water system failed (now , its on an injector cut off fail safe) and I detonated under boost at 5000 rpm - my stock bottom end survived with knock retard kicking in. (evidence by a compression test performed afterwards and its been 9 yrs later after that in incident. Same old bottom end).

the only thing id do is check your top ring endgap if you take heads off.

you want it slightly wider for boost bc it will want to close up under heat/pressjre - and that will break ring lands.

if yours is ‘narrow’ you will want to take it apart and file it.

i did not check this on mine - wish i did but am not going to take it apart just to check.

if it blows up, who cares. Ive already got 89000 miles on it.

also, if it cracks - the car is usually still driveable home, but may blow some smoke out exhaust and breathers

 

I'd rather build it like you said than to worry as much

What is a 355? If it is a 30 thousands bored over with a 350 crank then what is a 383? Isn't it just a 30 thousands overbored with a 400 crank. It would probably have to be clearanced for the crank but should be the same as a 355

See if you can find a dyno tuner who is willing to work with you. Remember, you are on an outdated platform and not everyone is jumping at the chance to work on it. Some will politely tell you to FO and others will be more blunt.

 

I believe the ZF 6 speed Vettes had a 3.45:1 rear end ratio.
Good luck with your build and welcome to the club.

 

Literally a waste of time. Striving for a lower boost number is just extra money spent for the exact same result.
If you're able to cool the charge air with the higher boost number, you're literally doing yourself ZERO favors by spending money to get less boost.
Why add a blower anyway and then strive to use as little of it as possible?

 

I mean technically with a blower... and I may be wrong about this but... the same blower on better heads will make less boost but more power no? IE better efficiency correct... Boost is still just resistance to flow so making it flow better will allow more air movement with less resistance... I would imagine the same engine with the same power and different heads would still live the exact same amount of time... still a function of cylinder pressure and how much you can cram in there for ignition no?

 

Torque is a result of cylinder pressure.
If you spend $3000 on heads and make the same torque on less boost, you're just making the same cylinder pressure for an extra $3000.
Then the only difference becomes charge air temps. More compression, more heat.
If you have a good intercooler, 100 degrees of ambient pressure air and 100 degrees of 14 PSI of air have the exact same chance of pre-ignition.
Then you're just left with cylinder pressure and its risk of detonation. But you spent $3000 to make the exact same cylinder pressure so.......

 

joenova - would you say the intake air temp is the only ‘factor’ for causing detonation ?

what about the extra drag/parasitic load (whatever you’d call it) of driving a supercharger off the crank?

is that also a factor that can cause detonation?
or no.

 

Maybe in the same way that increased load from a heavy vehicle can slightly effect risk of detonation, but its not a major factor.

Keep timing down at peak torque and increase it as torque drops off up top. Make sure you're keeping the compressed air cool.
And run whatever boost you need to get the numbers you want... because its free.
I've ran 30+ PSI on pump gas with 10:1 compression without any detonation.
Big 4" thick intercooler and baby soft timing.

 

Great post,
How much timing , what fuel and any Meth used?

 

12 degrees of timing, junk 93 from whatever I was driving past at the time, spraying windshield washer fluid into the intake with a $40 DIY water/meth injection kit.
That engine had HUNDREDS highway pulls on it, 6,000 abusive street miles, and I did ~60 nearly consecutive dyno pulls in 2 days hammering out the tune.
When I took it out of my car and took it apart, it looks flawless. That's why its going into my C4 for my next setup.

Sure, I could've spent $5k on a larger cam, aftermarket CNC heads, an aftermarket intake manifold, bigger throttle body, etc and made the same power on 24 PSI instead of 30.
I feel like saving the $5k and however much downtime that would've created was well worth the 3-4 years of absolute ear to ear grins until I had a house built and let it sit.
A buddy of mine is driving it now with a slightly different engine, but all the same setup still.

 

my next step (d1-sc / 12.5psi boost at 6400 rpm, on 93 stock bottom end with afr195 heads / 61cc chambers to lower SCR to 9.7:1 , meth/water inj - no intercooler) is gonna be to build up my fuel system to go pure e85

e85 is everywhere in ohio

ill add a few degrees (probably 2 or 3 degrees) more timing under boost to the tune.

if all seems good (no knock activity), i will prob pulley down for 15 psi max boost.

im currently on the 3.70 “ 8 rib pulley and 3.55” is the next size down.

 

E85 is amazing. I feel gross everytime I have to fill up the C4 with 93 when I'm out on a road trip and don't know where E85 is. Luckily the flex fuel sensor takes care of the tune.
I add ~6 degrees with E85 compared to 93. E85 is magically boost food that is cheaper than pump gas.

The funny part is, absolutely NONE of my fuel system is E85 compatible and I haven't had a single issue in 3 years.
-Cheap ebay fuel cell with who knows what kind of foam.
-Twin AEM380 pumps that specifically say "greatly reduced life when used with E85"
-Summit Pushlok line, which is just cheap hydraulic hose.
-Whatever fuel filters I can find (typically diesel)
-Deka injectors that aren't rated for E85
-OEM fuel rails and regulator that aren't E85 rated.

I am swapping out the fuel lines, rail, regulator, and injectors this coming year, but only because I'm upgrading for more flow.

 

If he puts 8 lbs boost to his 350 he will make more power with a 300 cfm head than a 200cfm. Wasnt trying to imply he could run less and go faster

 

I see both sides.

1. pulley down and make more boost is gonna be cheaper/less work than new heads.


2. if you can make the same power at 8 psi (with new freer flowing heads) as you can with 12 psi on restrictive heads - then you are surely heating the Air less/not getting as much parasitic drag from the s/c under boost and have a ‘safer’ build with less risk of detonation.

Detonation (on pump gas) is gonna be the limiting factor to his power - with the stoxk (or higher) compression that he has with his current setup

 

A pulley is cheaper than heads, and he will make the same power.

It doesn't matter how much you are heating the air. It matters how hot it is when it enters the intake. Boost pressure is mostly irrelevant here.
100 degree air at 8 PSI and 100 degree air at 12 PSI have the same chance of pre-ignition.
And if he's making the torque, then cylinder pressure is the same, and he has no noticeable increased risk of detonation.

Everyone seems to have bought into 90s knowledge of boost that you have to have super low compression or you'll explode, or that the boost number is the deciding factor in detonation chance.
Meanwhile 4-cylinder bikes are running 13:1 compression, revving to 14,000 RPM, all while only running 91 octane, and guys are adding boost to them and still running pump gas.

This section of the forum seems to be stuck in the past.