300

 

In 5th gear it takes 300RPM.

 

That is amazing. Not certain that I have ever tried that. Usually when I am in 5th my rpm's are much higher. Even with the stock twins when i'm doing a pull I keep the rpm's >4000 to be in the second turbo's range (not in 5th of course).

I see you're selling your FD with the BNR's. Does that mean you've decided that you like the GT35R better?

With what i've put into my car already it would have been more cost effective to have purchased yours. Not certain that I could learn to shift with my left hand. Did you have any difficulty with the transition?

 

He is saying it takes 300rpms from the point he goes WOT to hit full boost...He is not saying that he hits full boost at 300rpms.

 

Styx, did you go with a T3 or T4?

From what I've gathered is that the T3's can take a beating but choke off up top, and T4's don't have the greatest reputation (although garret has a good replacement plan for the CHRA I think?) for durability, but this is just from random threads I've been looking at the past few days.

I think I'm going to go with a T3 1.06. Will T3 turbo's spool better than T4? Anybody have specs on the GT3574R? Will a GT3574R T3 1.06 spool quicker or slower than a T3 GT3582R and would it be quicker spooling than a T4 .82 GT35R?

 

Afaik GT3574R is a T4, not sure if it comes in T3, I'm sure Zero R will chime in.

 

Thanks for clearing that up..... Makes sense now.

My car is at the RX7 store so I'm going with their kit. They use a T4. I believe I read that a T4 divided 1.06 spools faster than a T3 but don't quote me on that. I told them to go with an 0.82 A/R as I'm more interested in a DD than a track car ie. Low end response vs. Max output. I was going to call Jason tomorrow as I'm not certain if their T4 is divided (looks like it from the kit's pictures). I'm also unsure if the 0.82 T4 comes divided, it may only be the 1.06. Then the question is response difference between a divided T4 1.06 vs a single T4 0.82.

I'm still to much of a newbee to sort that out. I'm also still not certain of the effect of a short vs long manifold on the entire setup.

If the car has a straight exhaust I've been told spool is faster although logically it would seem that the reduced back pressure would favor higher output not spool.

If anyone has the answers please jump in.

 

My Fd (with down pipe and cheap air box mod) got full 10psi at 2,400 rpms.

 

I believe you should go w/ the 1.06. t4. I have driven a car w/ the .84 t4 and mine the 1.06. The top end choking of the .84 @ 15-16 and more psi was felt. The 1.06 the car runs out until you shift (and has more to go ). The spool time is not noticed unless you are out of the rev range. Once you learn how to shift and keep rpms the smaller hotside is obsolete. That is for the 35r. If you go w/ a bigger compressor side then the .84 might be a better option (500r or 67mm equivalent). G

 

I get 10psi on my .82 T4 35r around 2800rpm with a streetport. It spools really fast, not sure about 15 psi as ive never intentionally taken it that high and am not tuned for it. I will say with that housing its tough for a tial v44 to keep up and ive battled lots of boost creep issues on a nice hks tubular manifold. I may switch to the 1.06 just since guys say you dont really notice much of a difference in spool and the larger housing should be better for boost control.

 

I agree for top end performance the 1.06 is the way to go. I wish I could drive both cars as you did. Right now I'm only familiar with the twins. The car will 99% be a DD. What I don't want is to Jack rabbit around (and then brake) just to keep the rev's up for boost. That is ok for track but not so much for street. Without being able to drive a 1.06 I'm guessing that what I want is the 0.82. Boost creep problem is new to me. I think I will call the RX7 store tomorrow and talk that over with them. I may end up with the 1.06 or a larger wastegate (a Synapse 50mm is available..... Do you think that would help?).

 

Im able to hold boost with a high flow cat, just had issues when running no cat.

 

I've got a straight through exhaust system..... so it might be a problem with me as well.

 

Can you guys explain why you can not hold boost if you didn't have a cat? I ask because I was debating on removing mine.

 

This all depends on which "t4" you felt, if it was the one (T4 inlet)many have purchased through RX7store over the years then yes it will fall flat up top. Running a actual divided T4 would feel completely different as it runs a divided T4 volute not a T3 volute with a T4 inlet.

~S~

 

Yes.. divided.

 

Not sure why a divided T4 would feel flat up top. That's not what we see here.

~S~

 

Many reasons a turbo can fill flat up top. Usually tuning is the main issue.

On a .82 A/R GT35R we have seen 412 RWHP at 15lbs on a street port. Each car is a little different and porting plays a big part.

 

Can't wait to get mine back.

 

im not saying it was bucking losing power type falling out. just choking a bit w/ the .84 hotside

 

Just got my car back today from the RX7 store.

I went with the GT35R and a .82 divided T4 hotside. I was looking for a DD with twin like low end performance. RX7 store streetport rebuild and full exhaust.

Dyno @ 380.3 SAE HP with 290.3 torque @ 16.5 boost. It develops boost of 10.2 @ 3800rpm - higher than I expected with the .82 but there is virtually no lag. It spools up very quickly. I just played with it a little tonight. From a dead stop I can still smoke my wheels just like the twins.... But at about 4100rpm and up there is no comparison.

I did several pulls to 120mph before I ran out of room on the road..... I was at 6000 rpm in 4th and still pulling hard.... And it got up there in a hurry!

What i really like is that if I drive it "normally" up to 4000rpms it is just like my stock twins.... A nice DD. However.... If I step on it past 4000 - it develops an entirely different and very evil personality that my twins were never capable of.

This one is going to be fun to drive!

Thanks to Zavier and his crew.

 

I didn't know they made a divided t4 in .82, is that new? You might want to check for boost leaks, 10psi at 3800rpm doesn't sound right for that turbo and a streetport, to should be hitting that almost 1000rpm sooner.

 

Awesome styx, sounds good. I think I'll be going with a similar setup. But that 10 psi at 3800 rpms does sound a bit fishy from what I've gathered so far

 

^+1.... Does seem alittle slow. Nice numbers.... I bet it's a blast to drive!

also like someone already said, check for boost leaks

 

The .82 A/R is undivided, 1.06 is divided. It should reach full boost before 3800 RPM. If its running well I wouldn't worry to much about it. I didn't tune the car so not sure what the A/F and timing is set at.