I posted this over on thirdgen.org first since it applies to a thirdgen, but I thought I'd go ahead and post over here too. I'm new to the whole turbo scene, and I know there are a number of great books out there, I just havent had a chance to pick any of them up. I got help from my brother all weekend to put together what I've got so far.

Anyway, my ultimate goal is a single turbo 427 small block. I want to go single turbo for a number of reasons:

1. LT1 style accessory brackets leave the entire driver's side of the engine bay wide open.
2. Less of a plumbing nightmare with single turbo
3. Cheaper
4. Keep A/C

My initial thoughts for the engine are as follows:

-World Products Motown block
-Eagle H-beam 6" rods
-Undecided 4" stroke crank
-JE 4.125" pistons
-AFR 227cc heads w/64cc chambers if possible
-LT4 intake or carb manifold converted to EFI
-Custom headers
-Custom COMP cam, same as Monty is running in his vette

I made up an MSExcel spreadsheet to look at different engine sizes, rpm ranges, boost ranges, and the resulting flow requirements. So far, the only compressor map that I've found that is anywhere near what I would need or want is the T88. After reading through some of the other posts, I assumed an 85% VE at 6000 and 7000 rpm to simplify things a little. As you can see on the map, I plotted both sets of numbers. Obviously, as calculated, 15 and 20 psi at 7000 rpm gets into uncharted territory, but I really doubt I would turn it that high anyway. Also, I'd probably only run 10# for the most part, maybe 15 or 20 at the track, obviously with race gas.

Here is the T88 compressor map I found.

Here is the drawing I made.


Also, by my calculations, I could have 10# of boost at 3000 rpm.

Now here is my main concern. Does any of this sound even remotely feasible? I'd probably also run an intercooler similar to Monty's setup to keep the intake temps down. I've got a year to plan this out as I'll be getting a substantial loan Junior year, I just want to have a good plan before I get to that point.

Any and all suggestions will be appreciated.

One more thing, I'm going to do a 427 no matter if I turbo it or not. I may even build it up first, even with the low compression pistons and just run a nice n/a cam until I do the turbo system. Just depends on how much the entire project would cost. I'm definitely not doing this on a "high school" budget, but its not going to be unlimited either.


-Tristan

 

Ok, after a lot more research, I've narrowed everything down quite a bit. I'm seriously looking at the Motown 220 Lite heads, they come assembled for $899.99, don't think AFR is going to be able to beat that; and the Eagle 4340 4" stroke crank.

Which size combustion chamber would be better? The AFR's have 76cc chambers, Motown's have 64cc. I would think you would want the larger chamber so that you dont have to run as much of a dished piston, but I read somewhere that you want the smaller chamber for boosted applications because something about keeping chamber temps down and such.

The main thing I'm still wondering about is the compression ratio. I only plan to run about 10 psi max on the street, probably go up to 15 or 20 at the track with methanol injection and/or race gas. Since I only plan on running 10# on the street, would 9:1 pistons be alright? That gives me an effective compression ratio of 11.5, which would be acceptable on 93 pump gas.

thanks for any help

 

you would probably want the AFR's because of the bigger combustion chambers. The bigger they are the lower the compression will be.
I am having a stroker built right now for a single turbo and I couldn't find anything over a 383 to make theCR lower then stock

 

You don't need displacement for a turbo motor. The age old "there's no replacement for displacement" doesn't mean as much when you're talking turbos. That said, why not just build a killer 350 from a stock engine block and turbo that. It would be more than enough for a street car and wouldn't cost nearly as much as a big inch small block. Plus there's a million parts for a stock displacement SBC to make a bullet proof, low compression motor.

93turbota

JE/SRP now offers a set of 33cc dished pistons for a 383 that uses 5.7" rods. Real nice pieces.

 

There are a number of reasons I am choosing to go this route, mainly because, even if I don't turbo it, I am going to build a 427 for my car. The way I figure it, it will not cost that much more to turbo the car when you take into account the fact that, to change the engine to support boost is a matter of a cam and piston change, I will be getting an entirely new drivetrain to include G-Force T-56 and Moser rear, as well as FAST EFI system. For the cost of that all that, it will cost relatively little more to nearly double, if not triple (yes I know that's pushing it, but you get the idea) the horsepower output. The cost to get the turbo related items will be small compared to the overall cost of building the engine and upgrading everything else to support it.

 

Hope you've got about $30K to spend.