It sounds like the back pressure with the .68a/r turbine housing was a bit higher than ideal. I bought a .81a/r housing for Jeff, in case the .68 was too restrictive. It sounds like there were other issues with the car (main seal/tires) so they did not get a chance to swap out for the larger housing.

I am sure Jeff will update as soon as he can. 463whp on low boost on a DD is very good though.

 

i remember u saying the .81 ar was on backorder for months... .81 is the jack of all trades. 1.xx ar the supras use for their +800whp single turbo builds.

 

wow, hopefully everything gets sorted! i didnt know you could do a main seal replacement without pulling the motor. Was that a problem before going to the dyno? Given Jeff's goals (8500 rpms, high boost), I'd imagine that the 1.06 AR would even be better suited.

hopefully Jeff updates soon!

 

Yeah, just have to do some dirty work, removing the pulleys up front to get to the crank pulley. Once that's off, you can access the front main seal. The rear main seal, is a bit of a biotch forcing you to remove the tranny.
Hopefully he gets a chance to get back at it with the .81 A/R housing for even better numbers.

This is all great information, because all the while, this kit is evolving and flexible enough to improve with time. While the other turbo kits are "what you see is what you get" type. No way to improve without some other great expense. Glad to see the great customer support and willingness to change based on customer needs/demands.

 

Thank you. This is the reason I was looking for somebody with a built motor willing to push the kit to it's limits. I welded an extra bung just before the T4 flange just so Hal @ IP can log back pressure. Like you said, there are many kits out there, and for the most part there are no options. Once we figure out what the ideal a/r housing is for this set up, this kit will be the top ST dog out there. At least this is my goal, and the price for a tuner kit will still be under $5000.

There may be some more R&D this winter with something that has never been done on the VQ. Once I figure out how things will go (fitment wise) I will post pics and results.

I will also be looking at the twin scroll option here shortly, with the SP quck spool valve. This will help the large turbo spool up quicker, and retain that awesome top end.

 

Damn hopefully the people that own this kit would be able to upgrade to the new setup easily.

 

Your sticking twins under there.......

 

I said that it has never been done before...

Maybe twins, but not identical.

 

so it sounded like the car was fixed, any more updates on hi boost?

 

the tires were getting toasted on the dyno so they had to stop at low boost.

 

I hope that would be an option! that would be even better

 

I honestly don't think it would work out. It will be a whole different animal.

 

Compound Turbo system....sweeeet!

 

isnt he running 305 MT DR's?

well that pretty much sucks. I bet Jeff is super bummed. I would be.

Whens the next dyno day?

 

hey guys, getting on to post a little bit.

i am pretty bummed but **** happens. Main seal issue sucked and ate through our time. We had to move a bunch of cars around to get mine on the lift so it really chewed up a lot of time. The DD dyno doesn't like sticky tires because it heats them up real bad. I didn't think about this and again, with lack of time we couldn't get them swapped. At one point they were almost 200* when i checked them with a temp gauge. Hal said when that happens they get squishy and move around on the dyno and also they swell and cause inconsistant pulls. He said it's too hard to tune when it's doing that.

So it did do 463hp at 13psi. I was getting full boost before 4k. I do not have the dyno's for this because it was kinda late and a lot was going on. I'm going to email hal and see if he can get some to me.

The housing was too small and the choke point. Sasha has a .81 a/r (or whatever it is) but i'm not sure if that would be the key fit or if i should go higher. Hal said there really isn't any mathmatical way of seeing how much more it would flow.

I've been really sick so i haven't been on much. I think i have a touch of the flu because i've been throwing up for 2 days. I thought it was just my hangover on sunday but it's still a problem today.

Overall the power of the car is really good. I would have loved to go higher for my pumpgas but as i told hal before we started i was happy with how hard it pulls. Unfortunately there are still some driving issues below 2k rpms that i'm going to send some logs and talk to him about. That's my main focus right now, getting the car back driving great so i will enjoy driving it. When it bucks and drives like crap i don't want to go drive it.

 

To elaborate on this a bit; the turbo that Jeff has on the car has the T4 .68 a/r turbine housing (65mm wheel). With this housing at 15 psi of boost, the back pressure (exhaust pressure before the turbo) was 35psi. From my research, one should be in the 1:1.5 ratio when it comes to this. So at 15psi of boost, the exhaust back pressure should not be more than 22.5psi.

This is why I switched from the smaller T3 housings to begin with. The T3 housing simply can not flow enough to let the motor breathe in the upper RPM range when shooting for high HP.

Other turbo manufacturers keep this information a secret, I choose not to. I think this is the kind of information this community needs in order to grow. I don't think I have seen any other posts here talking about back pressures with the small T3 housings. All you ever see is "why didn't this kit make 500whp" and then the nut hugging, guessing and finger pointing starts.

Just sucks that you guys had all the other issues and din't have time to swap the .81a/r in.

 

so sasha is the .81 a/r still too small? or its optimal performance. i guess thats going to be the big questions for us that are going for optimal performance. i want good midrange and top end. is there any way to calculate if we are going to need the .96 or higher? im very curious to know if i made the right a/r choice.

ninja edit: some info i found with a quick google search http://www.toysport.com/technical%20...bochargers.htm

 

Which turbo did you get?

 

It is very hard to say, as there really is no mathematical formula for it. I would guess that the .81 would be a good balance between top end and mid range performance. Hard to say what the .96 would do without testing it on a dyno.

This is why I welded a bung on the exhaust just before the T4 flange, so that Hal can see what the back pressure is like when going for more power.

I think it all depends on what you goal is. If you are shooting for the stars then the .96 would be the way to go.



Vas, he has the 6765 T4 .81a/r.

 

i really want to shoot for 600whp on my high boost setting, 525-550whp for the street all on pump. hopefully im not dreaming lol =). supras make this power on pump with the .81a/r same turbo but we have .5 more liter of displacement. all of the 800whp runs i seen from the supras are with the .96 or 1.0x a/r. i wish hal would chime in and show us some light. he has a successful single turbo setup with almost similar size turbo. maybe he can share on his knowledge.