Building a 2.4L EVO 9, few specs on the build:

• 100mm K1 series crank
• 150mm Manley turbo tuff conrods
• 9.5:1 Wiseco Asymmetrical pistons w/ upgraded pins
• GSC S2 MIVEC cams
• GSC beehive springs
• ETS vband manifold, recirc, cat-delete
• 4.0" ETS speed density intake (no MAF)
• Stock intake manifold, stock TB, EGR delete

To be tuned on 94 octane. Goal is about 500 to 550 whp.

I am wanting to know from those experienced with this turbo (or the GT3076R), whether given the specs and displacement of my engine build, if the 0.82a/r is the better choice of the two options? I am choosing the GTX30 in the first place, over the GT35, for its faster spool-up, and understandably I stand to lose a bit of that going from 0.63 to 0.82, but how dramatic of a shift might it be, and is the 0.82 in fact more compatible and versatile for this particular build being that it's 2.4L?

 

Disclaimer: I do NOT have hands on experience with this turbo.

Assuming it is twin scroll housing:
The stock Evo X turbine is 56mm, your GTX30 is 60mm.
Stock twin scroll Evo X turbine A/R is .89

I would go with the larger .82 since you went with the 30 sized turbine. I don't think this is something you would regret especially with ball bearing spool up.

 

This is for an EVO 9 build and is not a twin scroll housing - don't think you can get a vband hotside in twin scroll. Your logic would generally still apply though?

 

Yes you can get vband twin scroll and i've got the highest bc gt3076r evo record at 547 dynojet on a t3 .63. I'll be switching to twin scroll next year tho with a bigger turbine.

 

.82

 

Grimgrak says you can get twinscroll, then you should definitely do it.
There is an interesting post on the mazda forums, with data from mazda on twin scroll versus single (it is old, but science is science):

http://www.rx7club.com/single-turbo-...turbos-903210/

According to Geoff at Full Race:
"We have found the twin-scroll systems have higher backpressure at low rpm (which is good for turbo spool-up) and lower backpressure at high rpm (which is good for top-end performance). On the other hand, single-scroll systems have lower backpressure at low rpm (bad for spool-up) and higher backpressure at high rpm (which hurts top-end performance)."

Read more: http://www.superstreetonline.com/how...system-design/

 

i won't dispute the advantages of a twin scroll set-up but i've yet to come across anything short of maybe a T4 manifold for the EVO 8/9 that is designed for a twin scroll housing..

i couldn't get to the content at those URLs either, i think one might be restricted to members only, and the other 404

on paper the twin scroll set-up always seems to be advantageous but there again in practice the differences have a tendency to be marginal

 

T3 1.06 is the way to go. If you want t4 step up to a gt35.

 

twin-scroll T3 at 1.06?

 

I fixed those links. Check'em out.

~Jaraxle

 

No, in practice is where you notice the advantages of twin scroll more than you notice it on paper.

 

Yep but unless you live in vancouver where we have a first ever e85 station your not going to get 550 on 94. Infact our 94 is worse than US 92.

 

I don't. No e85 for me. The 94 octane I'll be using is Chevron - apparently where I live the only fuel that is actually trucked in; the rest, no matter what grade or label is pumped down the same line from Kamloops.

You really think 550 isn't possible given my build parameters? I could opt for some more 'go-fast' mods?

 

Do the 0.82 on a MIVEC big motor car. The 0.63 wont get you any more spool and just lose power out the top.

 

Thank you.