Alright well let me explain a little on my setup. I have a stock internals j-spec motor with a front mount and two msd 6als going to a first gen distributor. A Sakura Motorsports standalone if you have no idea what it is google it. I have stock injectors in the bottom and 750cc rc injectors up top. Greddy boost controller on 11 low and 17 high. And i premix with klots fuel lube. Lots more done just wanted to give you a basic idea. I got it dyno'd a couple months ago ill post up dyno sheet in a little. It made 298 hp and 315 wtq on 17 pounds which seems really good because i havent seen a stock TII making that much power. But it wont make power past 7k becuase it cant get anymore air and it tends to break up youll see on the dyno sheet because it just starts dropping making no power. SO HERE ARE MY QUESTIONS IF ANYONE CAN HELP ME OUT.


Is it not making it past 7k because thats my power band on the stock turbo?
Will rebuilding the turbo help?
Is 17 pounds to high and what could have damaged my turbo?
What can i do to make it to 9k without bigger turbo and having to port the motor?


I have been drifting it for a couple months now after on 11lbs and it runs amazing but i never drift on 17 pounds just straight line. Turbo seems fine it boost on 11 and 17 no problem to 7k full throttle but still wont make it past 7k just breaks off. My msds rev limiter is set to 9k.

 

Will a compressor upgrade on the turbo solve my problem?

 

I believe you would see lots of improvement in the top end range but it could possibly hurt your spool.

 

To make power past 7000rpm you will need a bigger turbo and engine porting helps a lot. You'll probably want a new manifold and a T4 class turbo

 

Heres the dyno sheet sorry it took so long been working a lot. I was off on the hp and wtq but i was close and it seems my power band starts dropping at 5500rpm and definately am loosing a lot of tourqe after 5k. This was on 17lbs on the stock turbo with stock internals. I want to get a bigger turbo but i dont have the money to port the motor and stuff because i would want to do rebuild everything. Does anyone know if it would even be worth getting a new exhaust manifold with a bigger turbo without porting the motor.
http://i864.photobucket.com/albums/a.../DynoSheet.jpg

 

Like arghx mentioned you have 2 problems, your on stock ports and your turbo is running out of breath. Your setup isn't designed to make power at high RPM especially when pushing it that far on the turbo. You can get an upgraded turbo which will help greatly but ultimately porting and a matched turbo for your needs would be the best choice. All depends on your budget and how far you want to get into it.

If you want to make power to 9k you need a very large streetport or even a bridgeport and then a turbo with the correct hotside to match. Your not going to do this with just a turbo change.

thewird

 

be careful winding out the stock turbo to that boost level. Your intake temps will be high and the turbo won't last long.

That torque is pretty nasty though. It looks like a dyno for an STi with bolt ons. And I see at the bottom that the correction factor was actually .96!! That has got to be the highest dyno I've ever seen on stock ports and stock turbo. I think you should make a thread in the 2nd gen dyno section with that. There isn't much of a safety margin here. You are pushing everything pretty hard and something bad could happen.

Turn the boost down before something goes wrong. A rule of thumb is 12psi on stock turbo for reliability.

 

Thats about what you expect for a fully maxed out hitachi. close on 300bhp. My car is exactly the same power I just call it 220rwhp because thats what it is. 12s in a 1st gen. 13 flat in a 2nd gen. Or like me failed driveline parts everytime I go out to knock in the 12 second bracket.

All those extra PSI is increasing the power spread. Theres another 100hp in it with a bigger compressor. But you will need more injector to the sound of 4x900cc as a bare minimum and a genuine 044.

If lazy buy a spare s5 turbo, send it to BNR for stage 2. If not lazy arrange it yourself without the backcut. Arrange the turbine housing machined/slieved for 2.75" dump if using internal gate, or 2.5 if using external.

Do not get a port job. Its not going to do anything positive. 10's have been done on stockports.

 

stock ports are your issue. no power past 7k on stock ports even with a gt4202.

 

Thanks for all the posts but i was pretty amazed getting those kind of numbers on a stock rotary i called bnr turbos and they lauged saying thats impossible but whatever haha. I need to just save up the money for a rebuild, port, and bigger turbo. Any suggestions on a turbo? Something thats not absolutely crazy i still need somewhat of a low spooling turbo for drifting. If it gets to high of a spool that just means i have to go faster and it gets more dangerous.

 

Can you afford a new manifold, downpipe, etc? or does it have to be bolt on? If it has to be bolt on, BNR is your only realistic choice

 

bnr = boost spike issues .. not so simple.

 

It doesnt have to be bolt on. Exhaust manifold is only $150. I have a 3 inch exhaust all the way back i can just chop my header and re weld it. I just dont have the extra thousand if not more to rebuild and port which i should probably just wait till i can because it would totally be worth it. This guy has a precision turbo he wants to sell for like $750 its like a t-50 : t-60 somewhere between that i cant remember. I also have 2 750 cc injectors up top but i need some bigger ones up top and throw those down low any ideas how big i should go for the top? Like 1000cc? 1200cc?

 

that doesn't even look like a rotary dyno sheet, a stock turbo on stock ports putting out almost 300WHP at 5k RPMs?

no.

 

If you want to maintain response

https://www.rx7club.com/attachment.p...1&d=1283640536

You don't need to turn your powerband into a lightswitch to get more HP. Your high rpm hp problem is you are running off the side of the compressor map.

I will be using external gate + no turbine backcut.

 

Its 100% spot on You got no idea sir. I can give you another one showing the exact same number.

What you think happens when you use a porting setup designed for peak at 4500rpm, a turbo setup to boost intake pressure to 1.1 times atmo pressure? You end up with a very wide power band and is very easy to drive fast.

 

i suppose there are some people lucky enough to get that magical car that defies the rest. i've yet to see a stock S4 turbo produce more than a few horsepower past 14psi though.

 

That's your problem, you're missing the 'and stuff' part.

Your lack of knowledge would be excusable, but your lack of respect for those who have forgotten more about turbos than you currently know (bryan at BNR) tells me a lot.

Dyno sheets don't mean **** ..... go get some trap speeds and then come and talk to us

 

stock turbo aren't at 17psi

 

That turbo will crap on you very soon if you keep pushing to levels that arent ment for it. As for spinning the motor to 9k, that requires the rotating assembly to be lighten and balance. Aggressive porting, bigger turbo, upped oil pressure, ect ect ect. But like you said you probably cant afford all this right now and it is NOT cheap.

 

How much of a power increase will i see if i send to bnr for a stage 3 rebuild and is it worth it? I heard you cant even get a 60-1 compressor into the stock turbo? If i did in fact send it to them to rebuild i would probably stay at 10 low 15 high. Would i still see 300hp on 10lbs? I also have another dyno sheet i will attach it shows the comparrison on 17lbs and when i got an act 12lb flywheel and unsprung 6 puck clutch its a pretty huge upgrade it was like almost 40hp it revs up nice its not that fast at all.

 

And yes it was a rotary putting those odd numbers

 

Dont laugh at the paint job she is looking a nice forest green now :]

 

If you run a more efficient turbo at a lower boost level the powerband may change and your torque will drop a lot. As for how much you will make at a specific boost level, well that still depends on the dyno and a bunch of other factors. I can tell you right now though that 10psi on a BNR stage 3 will feel slower than what you have right now. It will be lacking in torque in comparison.

I remember when I ran my T04S 60-1 (not a bolt on BNR, a full T4 60-1). At my 10psi wastegate spring it wasn't very fun, not compared to the 13-14psi I was running on the stock turbo. I'd get the BNR stage 3 if that's what you want and run it at 17psi peak then taper it down to 13-14psi at redline if that's what you need to do. A lot of boost controllers can be adjusted to do that. That's pretty much standard practice on a lot of 4 cylinders. A stage 2 would spool better though because it doesn't have the clipped turbine wheel. Maybe you should look into that if you really want to preserve the torque you have right now.

 

there is only one reason why his torque is soo nice..

Once the turbo is boosting over its efficiency range(12-13 psi). The horsepower will stop gaining but torque will continue to rise.