Turbo Selection KA24E

[Var]

.50 trim T04E compressor wheel
.60 A/R compressor housing 3" in / 2" out
Big Shaft Stage 3 Turbine wheel
360 deg. thrust bearings
5 bolt .63 A/R turbine housing


How well would this turbo work with a SOHC KA
With a log manifold and a decent cam upgrade

THings i would like to know.
Will this turbo choke before 7k rpm?
Is it capable of pushing over 300whp @ 14psi?
Will it spool fully before 4k rpm?

[SpeedMonkeyInc]

The .63 will be good untill 7K no problem. If you want to be sure you are making 300whp by 1 bar a 57 trim would be a better option. On that turbo you might be able do it by 12-14 psi. As for spool, I don't really know. On my car a .63 57 trim in fourth gear hit 6psi at about 2600rpm. Aside from that I have hardly driven my KA-T yet because I am still working out some issues. I was trying to get the car home the last time I drove it and I had trouble keeping the car out of boost! This is on an S14 though. SOHC would probably not be too different.

[MagnaDyne]

To me it looks like a pretty good match.

You should be able to make in the upper 300's for hp.
You will need about 550 injectors.

The earliest it can spool before it surges is a hair before 4000rpm.

[Var]

To me it looks like a pretty good match.

You should be able to make in the upper 300's for hp.
You will need about 550 injectors.

The earliest it can spool before it surges is a hair before 4000rpm.


What do you mean before it surges? DO you mean a boost spike? And what's the reason for it? thanks

[MagnaDyne]

Surge is what happens when your turbo pushes more air then what your engine can swallow. This is bad as it beats up your turbo.
Sense the ability to spool your turbo up mainly lies within the mainifold & turbine design. I don't look at when your turbo will spool ,but rather the soonest it safely can spool up.

For instance if you have an optimal turbine and manifold designed for your engine. You might be able to spool your turbo at about 3000 rpm, but you won't want to because you will cause the compressor to surge. If this is the case you will have to control your boost until you are above 4000.

Does this make sense?

[Var]

yes but i thought the case most of the time is that the size of the turbo (which determines the cfm obviously) which also coincidentally increases lag evens out. IE: you'd be hard pressed to find a turbo that spools TOO fast. If it pushes enough CFM's to overload the motor, it'll probably spool later.

Is it yout opinion that this turbo can spool TOO fast?

Also what is your experience turbos? No offense but your post count is minimal and i dont know you or your reputation.

BTW i forgot to mention the head will be P&P'ed + PDM Racing turbo cam

[MagnaDyne]

Also what is your experience turbos? No offense but your post count is minimal and I don’t know you or your reputation.

Hah, I like how people's knowledge on forums is based on number of posts. :)
I know what you are saying though. So, a little background. I have been modifying imports for about 10 years now. I have gotten a degree Mechanical Design (engineering) in where I learned a LOT on just about anything that has to do with a car. I have spent the last few years studying turbo systems and reading everything I can. Engine design, exhaust & intake design. Even Maximum Boost, the book people seem to hold as the bible for turbo design. While I don’t consider myself an expert, I do think I have come a long way from where I was 5 years ago, and have overcome the misconceptions of turbos.

With that, yes, you can find a turbo that spools too fast. There is a LOT you can do to decrease spool time, and the compressor size has little to do with it. I say this because the proper way to size a turbo is to select the compressor first. With a compressor matched your next goal is to make it spool as fast as you can. (at least how I design them) Like I said, there are many things you can do to help this. One of the biggest ones is a divided housing turbine. Another would be equal length manifold runners, and properly sized exhaust, etc.
A good example would be to slap on a tiny turbine to your compressor. All that exhaust flow is forced to spin the compressor up in a hurry. Too bad the added backpressure & pumping losses hurts the overall performance.
So I suppose my point is - there is a properly matched turbine just like there is a compressor. You can go to extremes to make your turbo spool faster, but too much can hurt the performance.

You are selecting a .63 A/R, and I am guessing that it is a T4 housing, so in this case, I don't think you will be in extreme danger of surging. However, if you were running an equal length divided manifold I would be wanting to keep an eye on it.

sorry that's soo long

[Var]

Not long at all. thanks for the info