That procharger I was lookin at is just too peaky for me.....sooo I am gonna turbo it, twin turbo actually.

You guys have any good sites, or info on compressor sizing? Anything will help.

I plan on using the 420 small block....two turbos w/ adj. wastegates, max boost for each is 13 psi, so a total of 26 psi max.....intercooled and fuel injected.

Anything that will help I would appreciate.

Hunter

 

I would recommend first reading up on how turbos work. just a tid bit, if the wastegates are setup to bleed hot pressure when the cold side reaches 13psi, your total boost is gonna be 13psi.. with 1 turbo or 10

 

I will have two wastegates, one for each turbo, so they will bleed off exhaust when each other turb os reach 13 psi....so 13 psi from one, and 13 psi for the other.

From my understanding of turbos and wastegates, this is rihgt and would work, but if i am wrong...wow smack me around and tell me whats right.

Hunter

 

Depending on how you install the wastegates they open when either the manifold pressure gets to a certain point or when the exhaust back pressure gets to a certain point. Either way you won't be able to tell which one is making more boost since they both feed into the same manifold (unless you are Mike Moran).

 

13psi from each turbo.. = 13psi at the motor.

remember partial pressures from HS chemistry

 

Mike Moran had 4 turbos and two completely seperate intake manifolds He could and did run more boost on one side. Then again that engine made 2400hp and never made a good pass.

 

Well I guess I was wrong.....

So for sizing a compressor, how would I go about that, if I wanted 26psi total?

For my pressure ratio, would this be right:

(26psi+14.7psi)/14.7 psi= 2.76 as my pressure ratio?

I have not figured in any intercooler pressure drop.

When I am lookin at the compressor maps, obviously from the calculated engine airflow needed, it would be half for each turo, but this would be the pressure ratio for ONE of the turbos?


What my basic idea is:

420 CID Mowtown block
210cc AFR Heads
8.9:1 Comp. Ratio
Forged Internals
Two Turbos(one per bank), inercooler
Solid Roller Cam

I am aiming for about 800-900 HP and simliar on Torque, which shouldn't be too hard.

Anything is appreciated. Thanks

Hunter

 

http://moreboost.org/turbos.htm

Here is a good link to some turbo sizing.

Mike

 

There has been a few that have made 1100-1200 hp (flywheel) with twin 60 mm turbos.
Are your hp wants flywheel or rear wheel?

Why stuck on the 26 psi thing? If you make 900 psi only using 15 psi why use more...

I choose twin t-66's but shooting for more than 900 hp


Also if you notice Morans motor it went into a single bottom plennum which i didn't get but hey its all good Heard he has now gone to twin turbos rather than the obscene quads.

If I were you i would call Innovative turbo, or Limit Engineering and talk to some of the techs on turbo size and see what they have to say.

Steven

 

Flywheel, hoping for 900.

Im not really stuck on the 26 psi thing, if 15 psi will do it, then thats fine for me.

I think I will give Innovative turbo a call and see what their techs have to say.

By the way, what brand turbos are you guys using? Have any preferences or bad experiences with any specific companies?

I see lots are using turbonetics, a few are using garetts.

Hunter

 

I run innovative wastegates and Limit engineering turbos (john craig) turbos.

Steven

 

I guess I missed that part. That engine ran like crap anyways, the fastest I ever saw it go was a 7.50. It was only legal at the World Street Nationals!

If all you want is 900 flywheel hp then a single T76 with a decent engine can do that. Mine is some Job spec Innovative turbo good to 950hp. He has a car running 8.4s with it on radials so I believe the figures

 

I will be using my car as a street car, so the advantages of using smaller compressor housings for a twin turbo setup will work much better for me.

I have narrowed the compressors down to about 5 different ones, so I will be calling manufactuers soon and see what they say.

Who is using a Spearco intercooler? I know these are great quality as I installed one on a custom twin turbo 8 series BMW, but I am curious about how much pressure drop they have. Spearco says less than .5 psi, but has anyone tested theirs or heard other wise?

I will proably be going with Turbonetics ball bearing turbos, Spearco Intercooler, but havent decided on wastegates, or BOV's.

Will post progress though.

Thanks guys

Hunter

 

Where are you planning on mounting the turbos?

I am using two spearco intercoolers on my car ducted seperatly to my intake.

I have never used turbonetics for a turbo so do not have any personal experience with them besides calling them and talking to them on the phone. Really was not that impressed personally (opinions are like.... you know the rest)

Are you making the headers yourself or having them farmed out to someone else? Good luck on the build.
Steven

 

little tip for you.....most turbo companies are just buying parts STRAIGHT from garrett and marking them up. Certain ones are customized however but not too much. Like the "q-trim" for instance. I believe it starts life out as a p-trim and it is modified.