Anyone want to guinea pig the fitment of this along with the GT28 V-band discharge? Could be a good start to a very slick downpipe if it'll fit.

http://www.atpturbo.com/Merchant2/me...egory_Code=BCS

And I'm sure Wideopentuning would hook us up with a price on the two.

If I knew it would get past the firewall, I'd get it as I'm looking at upgrading my DP now.

Frank

 

it would be better if the sold it without the flex.

 

It looks to me like that angle cut at the elbow/flex junction is aiming the exhaust right at the bottom curve of the flex pipe. Seems like that would make a mess of flow. There's probably $100 worth of parts there - surely somebody could weld one up for $75 and make it more flow/miata friendly? Nonetheless I enjoy ATPs products/site - innovative stuff.

 

first of all, the turbine outlet should be 2-1/4 to 2-1/2.

second of all, that ****'s too big for a miata.

third, you only need a flex if your pipe is limp.

 

tell them to make this guy in 2.5"

 

if they made something, i'd go for a 2.5 with a gentle increase to 3 with v-bands at both ends. yum.

 

It's 3 inch so it mates to this:

http://www.atpturbo.com/Merchant2/me..._Code=ATP-FLS1

It's too big as in no way it will fit, or as in, there's no need for 3 inch? I could argue it's too big, just as a 3 inch exhaust on a sub 300 whp Miata is too big, but why limit for future upgrades?

Frank

 

i think external wastegating terms it would be big, as the turbine outlet would only be something like 2.5", but for the integrated wategate, 3" is probably best. right mr y8s?

 

3" on a turbo car is never overkill. Those that say it is, don't like faster spool... or freeing up power.
Heck... I'd run bigger or none at all if it was practical (noise/smell)

I doubt a generic piece like that would fit our very specific application. Getting one made would be wiser.

BTW... someone buy my ATP gt28rs Vband adapter....

 

Clearance at the firewall ledge and by the tranny is the issue for it being too big.

I though neogenisis bought that Vband adapter? Didn't yours have like 10 bolt holes? Are there different T28 outlet patterns?

Frank

 

He changed his mind on turbo. He'll be running something else, so I still have it.

 

That 3" looks similar to my custom setup, only with a sharper angle at the turbo. Should work very well. Firewall ledge can be cut.

 

Doesn't your HKS manifold drop the turbo lower though? Pics?

Frank

 

No, the HKS manifold is top mount, like a greddy. https://www.miataturbo.net/forums/vb...do=view&id=597

 

I saw the GT25 3" Vband flange.... which is OK but too big means too BIG overall. you'd need a 1969 camaro to fit that thing in your engine bay.

I think 3" on anything over 200 hp is great. i "believe" it helps spool. But it should be a smoother transition. like mentioned here and there the magic number is 11° divergent angle at the outlet.

So that's like 2.5 or so inches of expansion from 2.5 to 3" and then it's cool.

I tried to do that on mine but I'll be damned if the whole thing ended up even with the firewall.

Find me a 2.5 to 3" expanding 90 and we're talkin!

 

It can probably be done, but the manifold needs to be designed around fitting a 3" downpipe.

 

I think Braineack's solid pipe version will work. Not a very cost effective route to take though. You're close to 300 dollars with just top half of the downpipe and turbine flange. You still need to buy a v-mount clamp and figure out what to do with the lower half of your downpipe. You're probably better off having a local fab shop make you a downpipe.

 

Yep. My first DIY turbo had a "bell mouth" 3" downpipe, using the GT2560R and ATP's "oval" 3" flange. The turbo was placed so I could do a 3" pipe and keep A/C and P/S. I necked down to 2.5" down below next to the transmission. If/when I reuse it I'll cut off the 2.5" transition and keep it 3".

I agree with Y8S that if you had an external WG, 3" at the turbo flange is not good. You want smooth long transitions from 2.25 (or whatever the turbine outlet diameter is) to whatever size your exhaust is...3" right?! This 3" DP was for a normal internally WG setup.



EDIT: OH, this pipe was done with Vibrant's 3" pipe, not ATP's awesome tight-radius 3" pipes. ******* horray for those.