Spool time on this.....

[SHIEF]

A Garrett with a .70 A/R turbine side, and a .82 A/R compressor side on a basically stock (unless I do some porting before) KA24E. What RPM do you think this would spool up at? I searched and didn't find my answer. Or should I just save this turbo for a built motor? Thanks- Brandon

[IvoryJ30t]

well thats the ar spec, now whats the actual size of the turbo.

[IvoryJ30t]

a/r is the size of the nozzle, not the turbine or compressor.

[SHIEF]

Sorry, it's a T3, and .70 A/R is on the turbo housing itself, and .82 is on the exhaust side.

[IvoryJ30t]

t3 compressor and turbine

[SHIEF]

Umm...I'd think it's all T3, it's a stock turbo for something (some kind of truck) that came from Garrett and has never been on anything with downpipe. It's decent sized turbo.

[rco8786]

My semi-uneducated guess is somewhere around 2700-2900 depending on other factors. the t3 isnt huge to begin w/ so it shouldn't be bad.

[j-z]

thats gonna take a while buddy. remember all those diesel trucks have twice the amount of cylinders as we do. you also have to take into consideration of your rev limit. which is about 6.5-7k. you probably wouldnt even read boost on that thing close to 4k maybe 3.5k if youre lucky. i dont know exactly but thats my guess. in other words it wont be very fun at all to drive. youre gonna have MAJOR lag and not that much air being forced into your motor with a straight t3 as you say. just save and get a turbo thats properly sized for your motor. dont get one thats was properly sized for some big *** diesel truck.

[rco8786]

thats gonna take a while buddy. remember all those diesel trucks have twice the amount of cylinders as we do. you also have to take into consideration of your rev limit. which is about 6.5-7k. you probably wouldnt even read boost on that thing close to 4k maybe 3.5k if youre lucky. i dont know exactly but thats my guess. in other words it wont be very fun at all to drive. youre gonna have MAJOR lag and not that much air being forced into your motor with a straight t3 as you say. just save and get a turbo thats properly sized for your motor. dont get one thats was properly sized for some big *** diesel truck.

:rolleyes Somebody's never seen a T3 before...

[j-z]

nope i guess not. oh wait what was that thing on my prelude? yeah it was a t3. hes gonna have major lag with that thing. not even worth putting on a ka. how can you assume i have never seen a t3 before? doesnt make sense.

[MikeMurphy]

Anyways...

With a 2.4L engine and that spec turbo mentioned above, I would take a guess and say full boost of maybe 8psi and it would probably diminish to around 5 or 6 psi between 5000 and 6500rpm. Boost of 8psi reached at around 3800rpm, maybe even sooner.

T3 is fairly small so you will have some considerable backpressure in the exhaust manifold. However what you do have working for you is a favorable A/R on both your turbine and compressor, for the size of the turbo.

Please consider the above a guess.

EDIT: I read the A/R ratios backwards. Not quite as good of a setup. Full boost at 4200rpm maybe. However it should hold boost a little better on the top end, but im thinking beyond the KA possibilities.

[SHIEF]

Ahh oh well, it was internal wg anyway. If it was a T4, spool time would drop what maybe 800rpm? Doesn't matter I guess.

[j-z]

no your spool time would increase if were talking about the same a/r. what are you going to use your car for? that would help you pick the proper size turbo for your needs.

[SHIEF]

No, I know. I meant the rpms would drop i.e. 3800 to 3000. I will mostly drag it, but every now and then road course, and very seldom auto x.

[j-z]

no, it would spool at a later time. ie; t3 housing spool at 3.5k and t4 housing at 4k. just using those numbers as an example. well for road course and auto-x you definately dont want any lag at all. for drag you can compensate a little lag for more top end. will it be a daily driver? for road course and autox i would suggest a .48 a/r and drag .63 a/r. for street driving i suggest a .48 a/r also. when i do get my 240 i will be using a .48 a/r with a 57 trim compressor t3/t4E. mainly because i dont like waiting for power and i want it to be a fun car to drive. so if you dont mind a little bit of lag and want more top end go with the .63 a/r. if you go with the .48 a/r you will still haul *** no doubt. you just wont have to wait. so pick one.

[SHIEF]

Yeah but will a .63 A/R push around 450hp? It might be a daily driver, but it doesn't have to be.

[j-z]

oh ok. youre going pretty big. yes ive seen .63 a/r housings up there.

[C-Kwik]

nope i guess not. oh wait what was that thing on my prelude? yeah it was a t3. hes gonna have major lag with that thing. not even worth putting on a ka. how can you assume i have never seen a t3 before? doesnt make sense.

Regardless, it's still a T3 turbine. The size of the turbine wheel will be the most significant factor in regards to spool. The A/R more or less will fine tune it. I've seen T3/T4's with a .63 A/R spool up by 2000-2500 RPM to 9 psi on KAs. Going to a .82 A/R is not going to kill the boost threshold to the tune of some 5000 RPM. I'd say it will hit 9 psi by 3000-3500 RPM at worst. That's not bad at all.

Hell, my T4 turbine can spool to 6.5 psi well before 4000 RPM.

[SHIEF]

So this may not be a bad turbo then? Eventually I'll upgrade valves, retainers, springs and all head work to up my rpm's. Then weld the internal wg shut and go ext. So should I put this turbo on? Damn I'm a confused little boy.

[j-z]

i seriously wouldnt. i would get one thats properly sized for your needs. you mentioned that it was a straight t3 right? why even bother?

[95_240sx]

LOL. Who says turbo lag is a BAD thing? As long as you know whats coming, its cool with me. Wait until we see spool times on my T04X^2.

Rick

[j-z]

i never did say lag was a BAD thing. just from experience of driving my car and other cars lag sux! and you can go too big on a turbo size. ive seen it happen and man is that not cool. you still have to get a turbo thats properly sized for your needs no matter what.

[C-Kwik]

Properly sized is relative. It depends on goals. A larger turbo may respond slower but so long as it is still within the range of the motor's airflow at the intended boost, the larger turbo will yield more power. Trust me when I say many will not care about lag when they feel what 450+ WHP feels like. The Z06 I smoked in my friend's Supra sure couldn't tell that I was lagging.

But even for those who don't like lag, consider that what you are describing is not a huge step. It's still using a T3 turbine. Stepping up to a T4 would make a more drastic difference in response. And even a mid-sized T4 would not be a terrible turbo on a KA.

[Projex240]

Why would you guys see that thats a t3 turbo? I havent ever seen a t3 with those a/r's. Tha sounds like a straight t4 from a deisel. Not to mention a big t4. Desiel turbos that I can order all day long are about .82 or .84 with a t04b compressor, or a t04e compressor. The only thing that would lead me to believe that that was a t3 would be the compressor. Thats a common sized compressor for a t04s compressor. And those are usually mated with a t3 turbine. But oh well..its not my turbo..ill just take his word for it. The lag should be at full boost by around 3500-400o with a turbine housing that size. It would alsod depend on the wheel itself..though. hmmmmmm, thats a tough one.

[90lkn4swp]

I've seen T3/T4's with a .63 A/R spool up by 2000-2500 RPM to 9 psi on KAs.

C-Kwik would you mind sharing what stage wheel and also what size trim?

[SHIEF]

Yeah I doubt this is a T4 but I could be wrong I'm slightly new to the turbo game. I also thought those were big numbers for a factory T3 turbo. I dunno.

[Red Lightning]

Was this tuIs this turbo from a diesel truck? Diesel turbos aren't that efficient, because the diesel engines only rev to 4000rpm.

BTW, anyone know how much HP a T3 from the early 300ZX can support?

[SHIEF]

I have no idea what it's for. My friend got it from Garrett somehow and it's never been put on anything, it still has marks on the fins from the factory. So is there anything I can do to the turbo itself to help spool time besides porting and polishing the exhaust hook-up? Thanks- Brandon

[90lkn4swp]

i dont think there is anything you can do to the turbo itself to help spool it up at a lower rpm besides ceramic coating the turbine side but even then you might not see a very big change in response. you can mabye change the turbine wheel if you want to rebuild it. but then again i still dont have a full understanding of turbos so i cant offer you exact advice

[Projex240]

You won be able to "change the characotristics of the turbos sppol up unless you go into the turbo and have it rebuild with different specs. Too much money and time. If thats the case..just get another turbo. Also, deisel turbo are very efficeit, the only reason deiseil engines spin to 4k rpms is because the exhuast gases those HUGE engines spit out at 4000 rpms is enough to spool a turbo this size. Plus, the gearing on alot of deisel truck is so close, that they use up 20 gears to deisel trucks, so 4000 is all they need to get moving and a good pace.The turbo would be just fine for what you need, besides lag is only against you if yyou want to start a race at 1500 rpms or so..and since most folks start out at 3500-4000 rpms in a run, then lag isnt even a factorYou cant get rid of lag...but you can reduce the lag "time" if it takes you 3 seconds to build boost when going from 1500 to 4000, then theres room to improve. Use a lightweight fly, pulleys, a good 3 inch DP, 3 inch exhuast, test pipe, and if you want to, use a 1 peice 11lb driveshaft from enjukuracing.com. instead if 3 seconds, itll be more like 1-1.5.Thats about as good as it gets, bud.