guess I'll chime in.... While I don;t have any personal experience with a drawthrough system and meth.. i do have a ton of experience in using Meth on other forced induction set-ups. All of the points discussed earlier are all correct, you SHOULD be able to safely run more boost, more timing, and a leaner mixture. But all of these variables are dependent on many other factors. Things like, quality of fuel, ambient temp, humidity.... etc. So when others say that there is no magic number that is exactly correct. The only way for you to accurately gauge would be to put your car on the dyno and tune it. Anything short of that will probably be wasted effort. Also, finding "the limit" on a rotary engine can be a pretty expensive gamble, considering how little detonation it takes to eat an apex seal.

Another thing that needs to be considered and hasn't even been mentioned is the size of your compressor on your turbo. You need to remember that as you increase boost on this set-up you are also forcing more fuel through the compressor... this added mass has to be compressed as well which will create more heat and cause the turbo to become more inefficient. This is the exact reason why most people prefer to go the route of blow-through over draw-through, aside from the fact of being able to run an intercooler.

Soooooo..... as you can see this is not a very simple question. While I'm sure you won't want to hear my opinion, if you want to run higher than 10 psi then you should really look into going blowthrough with a front mount AND meth injection.

 

No, i appreciate your input... I am still a little confused while people are not listening to me when I say the system is drawthrough... I may switch to blowthrough eventually, but not tomorrow.
I'm basically running a Camden powered by my exhaust rather than belt... is the concept really that hard? lol

I guess I'll just focus on staying at 10psi WITH meth injection as a safegaurd against detonation. It's just I've heard of people running 15 psi on a stock port 12A all day with no problems... I don't know. I think I'll get my power I want with the heavier porting i'm looking at without any extra boost.

 

i have the same cartech kit ran it for years..do not run more then 12psi it will kill the turbo and stress your engine .take it from me i had mine turbo rebuilt 3 times. exhaust outlet from the manifold too the turbo is small and makes some back pressure..try strait water and cold air intake.....

 

Good to know... thanks for your input rx71king

 

 

most likely the extra boost won't hurt your engine. People say "it's not built for it" but I've never understood what they hell that means. High performance engines typically are only modded for RPM. name one preventive engine mod you'd need to hit 350-400hp if you keep the revs low and just boost it. Answer is: there are none. You'll use the same engine components. The beauty of rotaries are no valve train or rods to stretch. But the only way to really check you're safe is to log sensors that are only in place with fuel injection, hence the popularity.

Were I you, I would shoot for your intended boost number but have it dyno tuned so you can tell if it's misfiring or anything. Probably keep timing where it is if it's running well. Also note, pre-turbo water injection is superior and can make the compressor behave slightly larger than it is. (ex, if you run out of steam at 12psi, with injection you MAY be able to see a benefit with 15psi)

GO TO THE AUX INJECTION FORUM

 

Given my setup, adding MORE incompressible liquid PRE-turbo would only add more strain to my turbo (remember, I'm running a DRAWTHROUGH setup where the fuel is already "in the mix" BEFORE the turbo. My plan is to install the injector on the turbo outlet.

 

Even with the addition of the meth, DO Not run over 12psi. The intake temps are going to be high regardless.

 

Myself and a few others have already answered your question. My friend ran the same cartech drawthrough kit you have, and I have built and tuned a few blowthrough carb setups. There's no exact number we can tell you to run, that's why it's called tuning. You need to watch the intake temps as you increase boost to see how much you can run. The engine doesn't care how the fuel gets there, it only cares about the amount of fuel and the temperature. So with a rich tune and if you can keep the IAT reasonable then you can run 16-20psi or more depending on the seals in the motor. Stock apex and solid corner seals are good for ~20psi(or more), stock 12a corner seals are a bit weak though, always cracked on me above 16psi.

 

OK... so, I'm thinking of sticking with my current DRAWTHROUGH setup, but, upgrade my turbo to handle a ported 12A (street port or small bridge). Robert at RotaryShack recommended a T4 turbo, but, my constrained CarTech setup requires an internal wastegate.

I'm looking for recomendations... Finding a RayJay would be nice (but, I don't think they are internally wastegated).. and yes, I realize a ceramic seal would need to be installed.

So, I'm looking for a large T4 internally wastegated turbo on the cheap... any recommendations?

I'm thinking of going with GodSpeed turbo and have them build me a turbo. They seem to have plenty of internally wastegated turbos.

I REALLY need targets for Trim and A/R......

 

T4.... ok so we've narrowed it down to 304574507623408265132 different turbos from 250-1000 horsepower running 5-50psi of boost.

Seriously t4 is a family and means almost nothing. Go to aux injection and single turbo forums to learn about turbo sizing. You match a turbo to your power goals, NEVER to how much PSI you want to run as that is a pretty useless figure also.

for 300whp I'd recommend a small to4E, 57 or 54. With a .84 divided exhaust housing and a p-trim exhaust wheel. I have a 60trim and it's good for 400whp if everything is perfect. Most seem to hit 350-375. So that should but you just about there with fast spool at a streetable boost level.

A/R is another one of those useless figures until you've picked a specific turbo. A 1.00 A/R on a GT42 has NOTHING to do with a 1.00A/R on a TO4B, they look nothing alike and perform nothing alike. That said, the higher the number the bigger the housing. Larger ones have more of a headrush in high RPM at the cost of spool time, small ones come on line quicker with the price of feeling breathless up top.

ditch the internal gate. Waste of time on a rotary.

 

Thanks tasty danish, I realize there are a lot of options out there and thanks for rounding it down a bit.... I also appreciate your quick size suggestion.

Also, if i could "ditch the internal gate" I would. As I've explained above, it's a constrainment of my current setup.

My target is 10 psi and (optimistically) 300hp

 

The real reason I wanted to clarify how useless "t4" is as a marketing term, is all over ebay you read hype like: T4, 1.0 AR!!!!!!!!!!!!!!! and that tells you absolutely nothing about the turbo at all.

Frequently noobs come on here and ask "would a t4, 1.0ar exhaust .7 ar intake be good for my car?"
and there is no answer as they have specified no turbo.

Rotaries flow a lot of exhaust, I think you'll have boost creep nightmares that will never go away if you stay internal. Also, just FYI: streetable boost is typically considered 5-15psi, with extreme street 15-22ish. Unless you're in an EVO or Audi, damn those things boost a ton on pump gas...

I have a turbo miata at 200whp with a gt2554 and it still creeps 1-2 psi when it's cold. Imagine a 13b...

 

I'm aware of boost creep w/ internal gate setups... My RHB6 was a bitch till i ported it HEAVILY.
Maybe i'll just stick w/ my IHI turbo... It hits target boost around 3,400 rpm and holds it clear to redline w/ my street ported 12a. And if i'm running water/meth injection, that should cool the intake charge nicely.
Thoughts?
Am i really LOOSING power by running a smaller turbo?

 

why not try using a s5 turbo they have carbon seals . and will not let to much blow buy..... the front of the turbo lines up perfect to the cartech intake. some thing to look into.get a s5 turbo to mockup and see if it will work,......let me no and i will make u a manifold for you...

 

Exactly. Save yourself the Meth/Tuning headache.

Go e85!!

More Boost, No Intercooler, Much Much Lower intake temps.
Very safe for detonation, even with lots of timing.

God's gift to Boost everywhere!!

Tune for Lamda - and enjoy!

 

Amen! I want to run E85 so bad. Seattle is supposed to be hippy country, why don't we have ethanol stations all over the place here?

 

e85 sounds good. no one knows the long time effect on rotary engine. e85 is very corrosive and you will get some of it into the oil . just thinking the effect it will have on the bearings?going to open a engine running e85 for two years ....we will see...

 

Until you try to drive anywhere without passing a gas station...

How would e85 possible have an effect on IAT's? Not really sure about meth, but water injection is a dream to tune.

 

It has a much higher latent heat of vaporization than gasoline, and you're putting a lot more of it into the motor to achieve the same lambda. Result is ridiculously low IATs. Combine that with its higher octane rating, and you see why you'll typically run out of fuel system flow long before you see any knock readings.

 

e85 is NOT an option where I live. Closest station is 45 minutes away.

 

Well said, - Not to mention the cooling effects of a draw through
turbo system. They can Ice up even running regular gas, in the middle of summer.

 

My intake is REGULARLY frosted when I drive it around... yet people still give me grief how TERRIBLE a drawthrough system is and how you NEED an intercooler...

Yes, there is DEFINETLY more potential in a BLOWthrough setup, but, why can't I be different? lol

 

No one answered my question....

Will a smaller turbo really HURT my performance?
If I can maintain boost throughout my powerband than is the turbo really to small?

Maybe I should just look for a different turbo....

 

Well, I mean, yeah, if the compressor is out of its efficiency range that will rob power through higher IATs, or if the hotside is too restrictive that will rob power through increased exhaust backpressure. But by going with a bigger turbo it may (or may not) give you a less desirable powerband. If you can find a compressor map for your turbo that will help give you an idea.