RacerXtreme7

iTrader: (2)

Negative,

That would be a laggy no power having pig!

The T3/T4 hybrids DO NOT work well on rotaries at all unless you run small compressors. For a 60-1 there should not be anything less then a FULL T4 turbine wheel. Running a T3, even a stage 5 will yield slow spool and a choked up top end were running a full T4 p-trim and a .83 divided turbine and good manifold will out spool and out power any T3 sized turbine.

~Mike..............

BLUE TII

iTrader: (9)

I like the large exhaust wheel in a small frame high AR turbo housing for a great balance of spool and enough flow not to choke with our overlap.

I run a BNR Stage 4 based on a S5 hybrid turbo with a ported S5 manifold and exhaust housing (~T25 sized 1.00AR dual scroll) and 60-1 HiFi compressor P trim exhaust.

The way the turbo scroll outlets get ported for the P trim wheel actually raises the AR way above 1.00 (a digressive AR if you will).

This is a 4th gear 12psi pull on a dyno jet (which didn't load engine enough for 14psi set on manual boost controller and obviously spool is a little later than on the street).

55mph is 3,000rpm, so ~120rwhp there.



No problems getting full boost in 1st or 2nd ~3,800rpm despite the wheelspin on little 275 NT01. Full boost in 4th gear at 3,400rpm.

My turbo was even more responsive before I ported the velocity stacks out of the stock S5 manifold and the turbo housing up to the wastegate passages- but I had to do this to control boost creep when I had a monster street port.

Now with my mild street port limiting boost up top I am thinking of going back to stock diameter for the velocity/spool.

Got my 1st TTOD this last Auto-X

Build thread.
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/blue-tii-09-hillclimb-build-857528/

BLUE TII

iTrader: (9)

This is Andy's back on the stock port @15psi


I think he could use larger exhaust system and lower pressure drop on the intake side of things.

Do you have an updated dyno chart AMRX7?

AMRX7

Yeah, that's a pretty old plot. With a street port and gt30r sized turbo running about 17psi here's an updated one. Still need to get back on the dyno since this was falling off on boost too early as you can see in the torque curve. Would get to about 14psi and stay there until 5500rpm or so then go up to 16.5-17psi. Boost controller setting weren't quite right and I think my 44mm wg may be a bit too small for such a small turbo. Continue the initial torque curve slope up to peak and that's what it *should* be. That 250ft-lbs is at about 3500 rpm and if it continued that way would be 300 at 4000rpm (225hp).

BTW that old GT35R plot got much better with the street port (much more top end). Still had a slightly disappointing top end but the wg routing back into the dp then was very bad.

Net is that the smaller turbo makes as much power as the old GT35R, but boost is there at 3200-3300 as opposed to 3800 (this was on a dynojet so no load to help boost come on sooner, and 4.77 gears don't help either). A new manifold and dp by A-spec are why the smaller turbo makes the same power (or better).

I should say that while I think this makes a good autox setup, not sure I'd want such a small turbo (turbine wheel is tiny) for a street or track driven FD. Would likely run pretty hot.

-Andy M.

BLUE TII

iTrader: (9)

Nice!

If I calculate with your gearing 4.77 gear and 26" tire and my 4.10 and 25" tire we are exactly the same from 3,000 to 4,000rpm and then yours takes off which correlates with our similar spool and your higher peak boost.

I am hoping when I finally do get a dyno tune I will have the chance to do a race gas tune up from current 12psi to 20psi (8.5 rotors on mine) and get closer to 400RWHP, but I know I won't be able to match the GT series compressor for power/efficiency at high boost.

Yeah, I have the HKS 60mm GT wastegate.

I still have to get the 6"x9" truck filter and a 6" to 3" velocity stack from Turbohoses for the turbo inlet, that should help spool a tiny bit.