RICE RACING

WELCOME to turbo charged vehicles !

As the boost builds the more it comes in like a Hammer ! The less boost you run the less the issue.....

Mid size turbo's have this exponetial build up in power and torque in the low to mid range which upsets the mid apex and exit chassis balance. Large turbo tend to have this exponential rise on the later mid to top end rev range (just when you straighten up) and are preferable for my driving style anyway.

As I said the more boost you run the greater the problem is, in general I have found the higher up the rev range the better and in fact the less you stay of the wastegate the more the power generation seems to be linear, though you do loose some mid range punch. It is a hard compromise indeed but when you have only 2.6lt to play with and you want real high power there are not too many solutions to the equation. From my circuit racing experience I have found the car easier to drive the larger the turbine, I hope that the T51 when set to the same power level as the TO4S will be easier to drive again, at the expense of less mid range power due to less boost.

It is a bit hard when the power out put tripples over a 3000rpm band but that is why we drive rotaries !

Ojek

nicely said RICERACING

GarageBoy

thanks! So T51 is preferred of you have the $$$ and RX6 for "budget" applications?

Manolis_D

iTrader: (2)

I don't think that's quite what he meant The RX6 is good for about 380 rwhp, while the T51 is in a whole separate league (bridgeports, dogboxes, etc etc.). when you've got a T51 you're not messing around with 380 HP

GarageBoy

Thanks!

JBurer

I understand that the Garrett 62-1's are popular for road racing. That is what I am getting to replace my 60-1.
They're rebuildable, unlike the BB turbos and T-78. And, best of all, they don't cost much

I don't understand why one would want a compressor that is built to be efficient at 30psi (ie. T51-R) when you only want half of that for a road course.
If you're worried about power delivery coming on too hard in the midrange, then putting a larger A/R turbine on the turbo would be the way to go.
Best,
John

RICE RACING

John, a T51 is just as efficient at 10psi (400bhp) as it is at 36psi (800bhp) when matched to a well ported 13B engine & still has the ability to make even more power !

The big difference is that it can support the higher HP with MUCH less back pressure to the engine which will result in more power, at the expence of turbine responce in the low to mid range.

I agree with you that if you are after 400 to 550bhp (engine power) engine, then a 60-1 or similar sized turbo would be the best bet (all round performer) and like you said you can tailor it to deliver in virtualy any range you wish depending on specific engine set up of course.

Like I said when you see these things on a 1.5lt race car and they deliver the goods below or around 10k then they are realy not that big for a 13B that is built to rev to 9k, the argument of not having enough revs on board is crap in my books ! Most tracks I have been on your still got a fair component of the "friction circle" of the tire dealing with cornering load at revs near 6k which is the point in which the T51 "wakes up" and is delivering near full boost, just when you want it for the straight 5k to 8.1k with a majority of time spent @WOT from 6.5k to 8.5k was the reason I chose the T51, picking a turbo for performance below this point is counter productive unless you shift at 6.5 or 7k (factory redline?) I am not sure about you guys but from analyising reams of data I have the statistics pointed me to target the 6.5 to 8.5k WOT regions and with minor consideration given to 5k to 6.5k transient regions (mid apex, mid exit points) and this is when running with the stock wide ratio box. the T51 was a perfect choise for me even if I decide to run a 1 bar setting as it will extend the peak power speed of the engine and deliver power in the regions that "I" need it. In fact with the new turbo I am hoping to extend the usefull range to 9k rpm (without sever power drop off, as was noticed with the TO4 after 8k) which will be very usefull in certain situations.

Again pick what suits you and your engine, for most cases a TO4 or similar turbo will suit most peoples goals.

relvinnian

Hey Peter. With this new turbo, did you modify the intake/exhaust manifolds at all to allow the engine to breathe at your new 9.5k redline? My guess is no. If not, are you counting on the large increase in turbine flow, and more efficient compressor, to deliver appropriate average power up to this redline?

When looking at your previous dyno runs, I remember there being a distinct drop in VE% after power peak. (Which was around 7200rpm on the dyno if I remember right). You also mentioned your power curve shifted up as much as 400rpm on the street. Please tell us how you plan to overcome these obsticles. Where do you reckon you will achieve peak power/tq with this new setup on the street and dyno?

Thanks.

RICE RACING

I have made a totally new exhaust manifold, of a different design and
length......which is a great improvement over the one I was using on the
TO4S (flow wise) this coupled with the large turbine wheel, and larger
housing will lift the power band up 1000rpm in both torque and peak power. +
I will have a different Waste gate arrangement too.

Where as before, I was seeing 7600 to 7800rpm for peak power on the street
(v's 7200rpm on the dyno) I will be achieving peak power at around 8500 to
8700rpm from these different exhaust/turbine specifications.

The turbine wheel is truly MASSIVE (much bigger than a T88-34D or T51R"HKS")
when I went from a hybrid TO4 to a larger spec housing /exhaust it
shifted the power band up over 1000rpm, then I had a peak power around
6250rpm, this new set up makes the TO4 exhaust wheel side look like a stock
turbo ! I believe I will fully realize the potential of my radical exhaust
porting with this new combination as the old turbo was simply too much of a
bottle neck for high rpm operation.

There is a guy here with a very similar turbo to the one I have, with a bit
less porting overlap (street port) and he is making peak power @ 8700rpm
also runs a longer exhaust manifold too, so I should be right in my
estimation..........I will tell you soon enough