coolraptor

Yes, yet another ''I want boost. How do I get it?" thread. Iam not totally FI illiterate, but do appreciate some advice

Please forgive me on certain details as my memory is not what it once was. Also it has been a few years since my current setup has been apart.

383 lt1
Zero Decked block
Splayed billet 4bolt conversion
Eagle 4340 Crank/H-Beam Rods/ SRP forged pistons -3cc (i think)
Not sure brand or gap on piston rings, sorry!

Advanced Inductions 210cc Trickflow Competition heads (older version of 215cc setup I believe)
2.055 Int / 1.60exh valves
Comp 918 beehive springs
Paperwork says Chamber size ~62.00cc average
Head gasket is .040 thick

Cam is a low 23x/23x/ 575lift (builder said it worked out to 600lift however) on a 112 lobe seperation on 1.6 comp pro mag rockers.
Compression was supposed to be a hair over 11.1, engine builder says he calculated 10.50.1. Actual is anyones guess

Intake is stock ported (by engine builder)
TB is 58mm BBK
42lb Injectors
Granatelli MAF
Single intank walbro 255lph Pump.
Aeromotive FPR.
MSD digital 6al box, blaster coil, Summit wires (msd clones), NGK tr6 plugs
Rest of the car is built, can provide details if needed but that should cover most of the engine related stuff.


Considering using single front mount turbo, but not opposed to rear mount setup either (started a rear mount project on another vehicle, havent completed it yet however) wondering what the best & cost effective route to take is.

1-Obviously bigger injectors (7x lbs?)
2-Thinking dual 255lph fuel pumps (stock lines+rails OK?)
3-Easiest way to lower compresion? Possible to lower it enough without pulling apart shortblock? (main question)
4-Turbo size?
5-Current Cam OK?
6-Wanting to use stock manifolds if possible?

Goals: ~650wheel HP on 93 octane. Would like to be able to add race gas and push it harder at track. Not opposed to alky/water injection as well.
Will be keeping stock PCM & opti setup. (got all the bugs worked out now)

Car is barely driven on street at all currently, but it could change. Could be driven a few days a week during summer time.

I have another lt1 in the garage I could put together and try to budget-boost, but it seems like a waste when I have the current 383 that has a pretty stout bottom end already in it and paid for, know what I mean?

If I forgot something, let me know.
Appreciate any/all advice.

Kevin Blown 95 TA

That compression is pretty high. I calculated it at around 11.7 based on your information - maybe someone can check my numbers in case I missed something. Not sure how much bleeds off with the valve timing. If you went through all the trouble and cost of putting a turbo on it, you're not going to want to limit boost to just a few pounds or whatever is safe on that setup. Also, lot of guys broke SRP pistons with a lot less compression than that, although I think they were the dished ones. Your ring gap is important, so you are taking a chance there, too, assuming they were gapped correctly for a NA engine. The cam might work alright, but is probably not ideal.
The rear mount turbo is probably easier and cheaper to do, but less of a serious setup since it is away from the heat and then makes some amount lag trying to get the boost back up front. And there's not much room for the tubing under the car.
There are a bunch of turbo cars here, so you'll get their input. They usually make the radiator vertical to make room for the turbo. It's a bunch of work and expense to do that way, but cool as hell when its done right.

coolraptor

Thanks for the reply Kevin! I have no intention of boosting it as is, even I know that would be a timebomb, ha!

I wish I knew a bit more about engine building/calculating for stuff like this. I know enough to get me in trouble.

There is a local guy with a supercharged lt4 that has the vertical radiator setup, it indeed looks awesome. I read you could buy a direct fit radiator at one time, but havent been able to find it online lately. Ive always wanted to do that just to have some extra room if nothing else lol.

Iam still in the planning stages of course, its all in theory right now. Just wanting some experts advice since almost nobody around here does anything with LT1's anymore. Would like to have a plan of attack so I can get a realistic budget and parts list figured out.

Thanks for your reply

BlackbirdWS6

I would swap the cam for something boost friendly, go to a bigger dish on the piston (i like JE) and tweak the new HG thickness to get the SCR proper. Your target should be 9:1 to 9.5:1 SCR. You don't want to go too thick on the HG with FI to try and drop the SCR down to avoid tearing into the motor. You should do it the right way.

You have good size heads so you could likely do a -14cc dish and get close to where you want to be. A 76mm turbo should do the job for power, 80lb high imp injectors, dual pumps, stock lines and a good meth kit will work just fine. I make the power in my sig on stock lines and others have pushed them farther.

coolraptor

Sounds like an impressive setup Blackbirdws6! Awesome numbers for sure.
May I ask what you have for the hotside? Assuming your not using stock manifolds with those numbers? Just curious. I enjoy checking out other peoples setups, gives me ideas and stuff to go by

I will get the engine in shape first of course before attempting anything.

Thanks for the replies so far !

BlackbirdWS6

Thanks but I'm actually running a Procharger. Buddy of mine is doing a turbo setup on his LT1 from lt1boost.net and is shooting for big numbers.

coolraptor

Oh ok, still very impressive numbers!
The lt1boost stuff is nice as well. Have spent many nights looking at the pics on his website lol

DirtyDaveW

Like others have said, if you change pistons to a CC calculated to be in the 9.0 - 9.5 you'll be set on the motor. On the Turbo, for packaging, a lot of guys (like myself) went for a TC series (I have the TC76) but even the TC78 will not work well with your 383. The turbine sizes are too small , even for my 355. The smallest for you would be something akin to the PT 76GTS. I have used Realquicks (aka, Jon, aka LT1boost.com) log manifolds since 2008 but recently had some tubular manifolds from him(putting them on after getting them coated). Look at my sig to see the configurations of both. The log keeps the stock radiator, stock location. The tubular manifolds *should* also but I have to test fit to know for sure.

RealQuick

Any reason you want to use "stock" exhaust manifolds? Those heads and motor are gonna hate them.

coolraptor

DirtyDave- Sweet ride you have there sir! Still looking thru your page. Thanks for the advice, turbo-sizing is something I havent even thought of yet, mostly because I know nothing about it lol.

John-No reason really other than I have some laying around. If they are quite a big restriction I would have no problems going with something else.


Everything in the planning stages for now. Would like to have some more $$ together before I get my current setup torn down. That way I wont run out of $$ and have a non-running car. I appreciate the advice so far guys, Iam still learning on the Fi stuff!

RealQuick

For your setup (i.e. the heads and the cubic inch) I'd go with headers.

coolraptor

Alrighty thanks John! As long as the funds+job etc hold out, i look forward to getting started on this in a few months.