We're not talking the GT40R with it's ball bearing center section...just the plain jane version with it's regular CRHA.



A bit of background first...I currently run a GT40 (88mm) compressor wheel in my GReddy T78. The compressor housing is machined out to mate the new wheel. This turbo has incredible top end power and it pulls until the cows come home. Problem is, with my current setup, I'm not seeing full boost til about 5K rpm maybe a bit later. I have a collected exhaust manifold (not fully divided in other words).



So...with some people saying the 35/40's choke on top, why not just run a regular GT40 with it's T4 exhaust housing? I remember Magnus Motorsports saying there wasn't anything offered that would work well with a rotary motor.



I posted a similar question on the other forum and received an answer but after talking with others, I feel the recommendation might be too "drag" oriented for my tastes/goals which are:



1)an easy 425+ hp at 15psi, shooting for mid-400's and then some

2)full boost 1000rpm than I'm seeing it now

3)at least 8psi by 3krpm and excellent street performance

4)easily rebuildable

5)Something I'll be able to take up to 22psi or so on race gas and push 500+ hp



Now the non-divided manifold may make this tough. I've been told that running the largest turbine housing a/r would be a no-no but I'd like others opinions. If I can get the hp with the .94a/r then great.



Others who have this hybrind turbo combo (T78 turbine/GT40 compressor) say the top end is better than the stock T78. I need better response than what I'm getting now and something a bit more modern than a stock T78.



If push comes to shove, I'll switch to a fully divided manifold. Problem is, there arent' too many out there for the third gen that are south of the $1K range and if they are, they're typically mild steel.



I've been quoted at $1000 for a plain bearing GT40, any trim combo, and $1900 for the ball bearing version by a local shop. Good? Bad?



I'm going to post the compressor map, GT40 options, etc...I'm looking for what would be best for a street ported 13B=RE (Cosmo). Secondary ports are quite large and primaries are just cleaned up a bit. I'm est. 35-40 lbs min. in flow. Correct me if I'm wrong.



So which would be best (theoreticallY)? https://www.nopistons.com/forums/pub...1047683561.gif

compressor map

hot side...

Anything look good here? I'm just wondering why people haven't jumped on this turbo before...seems to be more efficient than a T04 series at a similar cost.

because new turbos are expensive turbos.......

True...but this thing has been out for a few years. Hey, why you at home this late on a Saturday night? Looks like you and I have no life. https://www.nopistons.com/forums/pub..._DIR#>/dry.png

yeah i know and there is no bolt on kit



actually. i just called ihor silver 93. he is in NJ for the weekend. i'm going to the bar with him https://www.nopistons.com/forums/pub...#>/biggrin.png

Got any turbine or compressor information on the T78, stock?



So if you like what the GT40 compressor wheel does with your T78 turbine,

and the GT40R turbine will spool quicker than the T78 based on the BBs,

do you think there is 1000rpm quicker response in the difference between the turbine map?



I do, Michel.

There IS a bolt on kit. Ask Ihor when you see him.

i forgot to ask him. all he talked about was the Gotham Racing Turbo Kit and how he was gonna woop my ass lol

isn't 35-40 lbs of air a little low for the numbers you want? Shouldn't it be in the 60lb range?

I was led to believe that a ported motor flows between 35 and 40lbs min. for a two rotor.



I hear what you're saying Tony, but rebuild costs man, rebuild costs...I'm thinking a regular GT40 will still provide better boost response than my current turbo sans the BB center section. I have no doubt the BB version GT40R will have a steeper boost curve. You've seen my logs and how late my current setup comes on boost.



So the question is, which of the compressors would best suit a rotary engine on the street with the previously listed parameters? Which exhaust housing?



Performance is never free (nor cheap!) but if I can simply replace my current turbo and spend about $1000 doing it versus $4500 for a brand new BB turbo kit, makes good sense to me!

The 88mm wheel. While I think the smaller wheel has an advantage, I think it goes away too soon. There is about a 2% difference from the 82mm peak to where the same point maps to on the 88mm wheel.



Michel, what RPM did you get that CFM quote for? Or are you talking per a rotor?



Tony

sounds like your in my situation. with my HKS T-45S, I build boost slowly...then at appx 5k rpms...hold the F#CK ON....all the way to 9k(and more...it still wants to pull).

Sounds like you boys need a half bridge https://www.nopistons.com/forums/pub...IR#>/bigok.gif

yeah that might be it https://www.nopistons.com/forums/pub...#>/biggrin.png

Someone on the other list gave me that flow number.

don't tempt me https://www.nopistons.com/forums/pub...R#>/tongue.png

you won't go full bridge!

nope. Half bridge with the rotor housing cut will give me more flow than a full bridge. I think I'll bridge the primary's instead of the secondaries.

????????????



Why? Never heard of that. Please explain

probably to get a greater air flow at lower rpms.

well, think about this. when porting the primary ports, your limited to size because of the water jacket right? So...if you bridge the primaries, you'll get more airflow than you would a streetport. Now the secondaries...you can't make them as big as a street port because of the "bridge" that the corner rides on, where as a streetport, you don't have to worry about that as much. So now you have a half bridge(primary) with cut rotor housings flowing tons more air.



Kind of hard to explain, but in person, it's cake. IGY did it on his rotor housings and I was amazed at the power it made(at .8 kilos boost I SWORE to never ride in his car again...and I haven't)

The primary bridge is a theory, the only real limitation I see is intake manifold/ primary runner size. This is why I want to try this using a cosmo center plate and intake manifold. As far as beveling the rotor housings, I was fairly sure that everyone did this unless they were following certain class rules forbidding porting on the rotor housings. I personally believe that for turbo charged rotaries that a full bridge extends the powerband to high in the rev range, and is of no benefit for the average person. 12,000 rpm's with boost is alot different than 12,000rpm's without.

I agree with you. There isn't really a need for 12,000 with 20 psi, but it does sound badass.



So why do most people bridge the secondaries, instead of primaries when doing a half bridge? Just trying to understand the logic between the 2. I had an indepth conversation with Judge Ito about this, since he will be building my half bridge. He never mentioned bridging the primaries instead......





Basically I want what IGY has. A car that will scare the piss out of people, and just put a huge smile on my face everytime I drive it. IGY what kind of power was your car making roughly?

lol...your going to have a beast of a car if you want to replicate IGY's BP motor. I was destroying cars left and right when IGY was tuning it. At 1.3 kilos, even 20B's were being left in the dust https://www.nopistons.com/forums/pub...IR#>/blink.png

Hmmm. You boys get back on topic....NOW!



Based on CFM calculations and VE numbers that are probably not right, I think this turbo is going to have a heck of a top BANG with a fairly decent spool up. I am most concerned with it at 17psi and around 5000rpm. Matched with the right amount of extra CFM from a large street port or a race port (the latter with more overlap between intake and exhaust....my definition for this post anyways) it will be nice. On a mild or stock port, I think you run the risk of being to left of the surge line....not enough UMPH!



Going to be a joy.....soon.

You're referring to the 88mm wheel correct? Which exhaust housing though...is the .94 going to be too small?

lol...your going to have a beast of a car if you want to replicate IGY's BP motor. I was destroying cars left and right when IGY was tuning it. At 1.3 kilos, even 20B's were being left in the dust https://www.nopistons.com/forums/pub...IR#>/blink.png [/quote]

https://www.nopistons.com/forums/pub...1047683894.gif https://www.nopistons.com/forums/pub...1047683894.gif https://www.nopistons.com/forums/pub...1047683473.gif https://www.nopistons.com/forums/pub...1047683473.gif https://www.nopistons.com/forums/pub...1047683329.gif https://www.nopistons.com/forums/pub...IR#>/bigok.gif

Hottie side 1.19AR!

It's actually a .95, but they do make 1.06



-Sean

Hottie side .95!

Where are the hotties? Just thought I would ask i figure a guy with your background must know.



-Sean

Come down to cow-town and I'll show you. Better yet, I'll come up to Chi-town and you can show me the hotties up there!

So the .95 will be best then? I did talk to someone else who felt the other two options would be a bit big and drag only.



Hotties. I'll show you guys some hotties. C'mon down to South Beach. You'll never want to go back to the midwest again. I've lived in both places. Chi-town is ok but no comparison to certain haunts in Florida. https://www.nopistons.com/forums/pub...1047683329.gif

.94 I mean....are there different options available on the 40R?

never had my hands on a cosmo center, but you could also use a 12a center section for more girth and cut out for the water seals on the aluminum. https://www.nopistons.com/forums/pub...DIR#>/wink.png this would be great (in theory, have not completed a setup like this yet ) if you were using a jay-tech intake like the quadIV throtle body adapter where the 6 injectors are plumbed in the manifold and no *primary* injector bungs were "needed". https://www.nopistons.com/forums/pub...IR#>/smile.png

I was talking to Rob yesterday...he mentioned the Jay-tech mani and good words about it and Jay. His words are Golden https://www.nopistons.com/forums/pub...#>/biggrin.png ...after all. I am thinking that the BRE (with it's inherently larger intake tract) would shine even more with the GT40R strapped to it.



I think the next engine will be a BRE, probably in a purpose built car with a nice cage built into the car and a dog box with some hefty drivetrain upgrades. After finishing up the #7 Rx-7.



Gee, Keith, where can we find the Jay-Tech manifolds?



Ok, Michel, you just have pull out your trump card about South Beach. I have a sister down there so watch who you touch! Actually, I'll be down that way at least once in the next 4 months. I'll have to give you a shout.



Sean knows more about the turbine wheels and what they will do. I feel confident that his choices will yeild some good results. The new manifold alone should impact the scroll-up speed considerably....what with the equal length runners and keeping that heat energy longer through less surface area of pipe. I wonder how much that metal is going to glow at night?

Jay will be offering them again. actualy i called him last night and have to call him back today. if you would seriously want one, let me know. the new ones are not finished, but he has the older style still. he just has a small amount of machine work to do to them and some lines to finish. but you have to understand something. a week in Jay's *world* is like a month in the real world. https://www.nopistons.com/forums/pub...DIR#>/wink.png https://www.nopistons.com/forums/pub...IR#>/smile.png