Probably, but by how much? How much does a 2.25 or 2.5" impede flow over a 3"? Who knows. All I can do is try to dyno at the same time and on the same dyno as other setups and let the consumer choose.

 

If you want it, you got it.

 

Damn it I forgot my sarcasm meter

 

shhh he was going to build it !!

tim, if you tell me the centerline radius of the pipes you can get and wall thickness and such, I can just CAD up my absurd pipe for paul's extra 100 rpm. perhaps there could be a little comparo at the dyno again. whee.

 

The vent tube on the BEGI-S pipe is now 6.5" to 7" long.
Stephanie

 

I'm sorry, I meant that your standard BEGI-S pipe is not 3" in diameter. Otherwise y8s drawing does look similar to your BEGI-S pipe and I guess FM's cast piece too.

 

thanks but I can CAD up my own Kinda hard to do the downpipe without having the entire underside of the car modeled too. I do use a modular Faro arm here at work...hmmmmmm...I don't think they'd let me borrow it for the night though. I don't think my salary can cover it.

I use 6" centerline 3" pipe, .060 wall. I use the usual pipes everyone else can get. 99% of the stuff is from Vibrant, other stuff is from Burns if vibrant/keystone is out of stock. You can get the centerline radii of the smaller pipes off vibrants website.

EDIT: If I were building a downpipe for my personal car, I'd be a bellmouth and no because it could be easier. When you take a 3" pipe and make it oval, it's about ~2.25" wide anyway and that 2.25" edge of the oval is centered over the turbine outlet. It's not like a 3" pipe is right over a 2.25 hole and there is no taper. So at least half of the turbine outlet is a smooth transition, the side against the oval edge of the bellmouth. The other half of the oval bellmouth is there for the rest of the exhaust and WG gasses to GTFO.

 

ok simpler idea then.

can you weld a divider into the oval?

 

The owner of Jesel says he'd never use 80% of the things we make here.

So yeah, I can weld a divider into the oval. The customer is always right.

The downpipe at the dyno day will not have a divider.

IF I were to do a divider, it'd be a burns transition cut in half.

 

Maybe just a section of 2.25" pipe or whatever protruding into the turbine discharge, but not going really deep into the bellmouth. Basically, something to keep the wasted charge from blasting sideways and disrupting the main flow at small wastegate openings. Like is cast into one version of the GT2560R.

Probably easier to do that welding it into the turbine housing, as long as you don't warp it, and if you have that available to work on. That's what was done on SCC's project Silvia Disco Potato.

 

Update.

I spent yesterday removing the twins and making this other stuff fit (and I only forgot to tighten one thing! woohoo). I ported the wastegate on Paul's donor 2560; the spring pressure is 8psi using the garrett wastegate actuator. It spools quicker than the twins and the exhaust is louder. I am running the same tune so far as the twins, I assume that will probably change. But so far so good. I will aim for at 14-14.5psi at the dyno day to try to accurately compare JohnDoe's SGDP dyno plot posted earlier.

The orange discoloring on the manifold is the paint I didn't remove from the weld elbow.

Before:


After:


Close up:

 

I made 264rwhp @ 12psi on my first run, 268@ 13psi on the 5th run with noticeable heat soak (notice spool difference). Peak boost was 14psi, dropping off around 5000rpm.

John Doe's was 14.5psi at some point. I am not sure if he was able to hold it to redline/hp peak. I sent him a PM to find out.

Big spool difference compared to the cast BEGI/SS SGDP combo.

For sale ad coming soon after I get info from JohnDoe and my datalogs to be specific about spool rpms, etc.

 

damn, that's awesome Tim. Any plans for us 1.6 guys?
__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote

 

I'll build whatever.