EVO8-9 we have 9 cm/2, 9.8 cm/2, and 10.5 cm/2 nozzle area turbine housings, most popular being the 10.5. EVOX has a 12cm/2 nozzle area.

 

Thank you for your data-based response. I'm pretty new to turbo design. What would the net effects of a larger nozzle area housing be? Mine is also ported if that has any bearing on it. It does seem that the 'smaller' Blouch turbo might actually be making more power...

You say fuel doesn't matter, which I would agree with, but certainly one turbo could be more efficient at high psi and one at a lower psi, right? Isn't that why people say the stock turbo is 'out of breath' ~28psi?

Also, if my turbo surges at 25psi, are you saying it will still surge at 30psi?

Thanks,
Ryan

 

The VIII and IX FP stock frame turbos have been improved over the years, the X has not. First there was the white, then green, then red, then 80mm comnpressor cover red, then HTA green, these stock framed turbos have evolved, the X red has not had that opportunity, that is what Robert is saying...

 

I think one thing you guys might be over looking is the head design. Particualy the exhaust port and valve size. I dont read much about evo x but i remember a thread that i think ams did about comparing both motors. They said that the evo x head intake ports are very well designed but the exhaust side was much smaller than the evo 8/9. It could be that the exhaust port on the head could be a limitation in higher flowing turbos.

 

The red is good for about 25-26 psi on pump gas... and depending on your dyno.. anywhere between 350 and 400 on PUMP gas.

here's the kicker... I put some C16 in my car, and retuned.... and you wouldn't believe this even if I showed you the dyno graph, but from 26-30 psi... my X hit the same dyno numbers.. no increase what so ever... and was laggier. Tuned through ECUTek, with ECU boost control.
My mods list is pretty extensive so that shocked me.... but the turbo did "overcome" that hump around 32psi.. and really shined around 34.5 psi.

So your best bang for the buck is to get some Alky injection, tune it to around 34 psi of boost, and watch the numbers climb. Good luck to everyone trying to figure this out.

-Chris

 

Wow no large gains until 32 psi? Even with water/meth injection I would be worried about going that high on pump gas.

 

from 26-30 No gains.

from 31-32, gains

from 32+ big gains.

I guess that "hump" does something with the air, and is not happy. But at 32+ psi, it is in love.

I hear you Chris as far as daily driving with alky + pump @ that high of boost, it doesn't sound safe... but I'm sure someone will try it.

-Chris

 

Wow... I myself, saw no gains from 25 going to 27 psi, so your logic is right. Can you let us know exactly what you made at each boost level? I would be willing to run over 30psi on meth if there's no knock.

But by then, I will probably ditch the Red in favor for something much larger.

 

I'm wondering if the housing can be ported further or extrude honed to reduce the back pressure that is building up if indeed that is the cause of lower boost levels not delivering the expected performance. I know in the good ole DSM days they used to "clip" the turbine wheels 5, 10, or 15 degrees to trade some spool for better top end flow.

I guess if they swapped in a turbine wheel that was less restrictive with less response it would potentially reduce the back pressure on the exhaust side. From what I can tell the turbo is very responsive considering it's not even a ball bearing center section so that trade off may be worth it. I'm also wondering if a full set of headers and O2 downpipe might lower the boost levels you need to hit in order to see solid gains from increasing boost.

 

Bingo... this is exactly what we saw when AMS tuned mine. Kept turning boost up and nothing... I've needed someone who knows turbo design to tell me exactly how this could be. I too have considered a bigger turbo. I don't think the head design is a limiting factor since AMS just hit 670whp on the stock head.

34.5psi sounds scary because I drive it daily, but I think E85 could handle it if the short block can. I remember TTP said something about the X block not being able to handle high boost. Does that mean that a higher flowing turbo at low PSI would be OK?

 

No headers, but most of us are running an O2 downpipe. Also, from what I know, clipping a turbo like the green or stock makes sense, but it almost seems like the Red's wheel is too 'big' for the housing. If that's true, clipping it would only make that situation worse. I'm not sure how much more porting is possible, and if I invested in that plus headers, it would just be 35R time for me.

 

Ryan Gates was running the FP Red @ 34 psi, if not higher, on 110 octane when he made like 450+whp on AMS dyno, with a stock long block... and he used it for a lot of miles, before switching to the AMS turbo kit.

E85 is equal to about 105-107 octane.... so you should be ok on E85 @ 32-34 lbs of boost, with the proper tune.

 

from 25 to 30 lbs it was around 365-370 range, didnt go UP until after 30 psi.

I opted to keep the 91 octane tune, because my car is for sale, and I dont wanna be responsible for the new owner fckin the motor up because he mis shifts at 34 lbs of boost.... would not be a pretty sight.

I will see if I can find the data, I might have written it down somewhere.

-Chris

 

I find it surprising actually... others have said that they aren't the same turbos which makes sense because just about every other basic mod UICP's intakes, etc make more power on the X than they did on the VIII's and IX's... or this is what I have read on this site multiple times at least.

 

E85 is more like 100-105 max octane... 34psi on that, would be on the edge IMO.