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sr20damn

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Discussion starter · #1 ·
does anyone have an idea of when a gt25r will spool up? (.86 A/R) and the max wheel hp that can be massaged out of it? and also the highest boost it will handle...please only defininate answers and no guestimates.
Thanks my fellow 240 drivers!
 
#2 ·
the compressor is capable of supporting 28 psi, but the turbine side will choke it off. 440 whp is the max you'll probably ever see out of a GT25R at 26 psi or so. you'll need race gas and good engien management. As i told you int he other thread. usually they make full boost (18 psi) around 4300-4500 but if you want 24+ psi you are going to have to wait until almost 5000 rpm for it.

Why the hell did you need to start another thread about this anyway?
 
Discussion starter · #3 ·
440 is a lot of hp, thats at the flywheels right? would you happen to know what rpm it would start to spool. i really dont want a laggy turbo, i want power everywhere and be able to drag on the weekends
Thanks Enthalpy
 
#4 ·
man...i'm not trying to be a dick here but it is sure going to look like it.

HOW MANY TIMES DO I HAVE TO ANSWER THE SAME FUCKING QUESITON FOR YOU? You originaly asked:

sr20damn said:
does anyone have an idea of when a gt25r will spool up? (.86 A/R) and the max wheel hp that can be massaged out of it? and also the highest boost it will handle...please only defininate answers and no guestimates.
Click to expand...


so i answered you...


Enthalpy said:
the compressor is capable of supporting 28 psi, but the turbine side will choke it off. 440 whp is the max you'll probably ever see out of a GT25R at 26 psi or so. you'll need race gas and good engien management. As i told you int he other thread. usually they make full boost (18 psi) around 4300-4500 but if you want 24+ psi you are going to have to wait until almost 5000 rpm for it.
Click to expand...

now in your original question you asked what the max wheel HP was. i responded that the turbo is capable of supporting 440whp. whp IS WHEEL HORSEPOWER!!!!!

you also asked about the spool time in your original post. I quoted rpms for both 18 psi and the boost required to make 440 whp.

but then you respond with this?


sr20damn said:
440 is a lot of hp, thats at the flywheels right? would you happen to know what rpm it would start to spool. i really dont want a laggy turbo, i want power everywhere and be able to drag on the weekends
Click to expand...
DID YOU EVEN READ ANYTHING IN MY RESPONSE OTHER THAN "440"?? I ANSWERED ALL OF THOSE QUESTIONS FOR YOU IN MY FIRST RESPONSE. Please turn on your brain before turning on your computer!!! furthermore, there not multiple "flywheels" on an engine. only one flywheel. but i clearly quoted you WHEEL hp not FLYWHEEL hp. the RPM that a turbo "starts to spool" is a very subjective term. some people define that as making positive pressure, other mean when will the turbo really come on hard. but either way. the RPM that a turbo makes full boost at is a better indication of how it is going to perform.
 
Discussion starter · #5 ·
lol whoa man take it easy....the rpm you wrote was at full boost. im asking when does it start to boost. if its at 4300-4500 wouldnt that mean this turbo has a lot of lag. i read in these forums that this turbo is supposed to spool quickly
 
#6 ·
4300-4500 isnt really terrible lag. the factory turbo just spools so damn early that it makes everything else seem slow...but the stock turbo is out of air by 6500 rpm and when you are racing you rearely drop below 5500 so it is pretty much useless for a performance application. you want a turbo that is going to maintain the TQ curve flat as long as possible. to do that you need to give up a bit of response...but you benifit in much greater top end power. everything in life is a scrifice. you need to give up soemthing to get something. thus is the case with this turbo. you need to give up a bit of spool to get more top end power. i run turbos regularly that dont make full boost until 5000+ RPM. Lag is all in the eye of the driver. but if you are on ful boost at 4500 and can make good TQ all the way out to 7500 you have just created a 3000 powerband. the stock turbo only has a 3000 rpm powerband...so trading 1000 rpms worth of spool for 1000 rpm more worth of top end powerband is really a good thing.
 
Discussion starter · #7 ·
i know your probably getting tired of responding to me so its ok if these questions gets left hanging....any tricks to making it spool faster?
like polishing things in the turbo or other bullshit
its ballbearing shouldnt it spool at like 1000 rpms or something like that lol?
is there a similar turbo to this one but spools a lil quicker? (BB)

like i said i need a good daily driver but something that would really shock people at the track...you,ve been a big help so far. especially since all this really technical stuff is new to me. BTW how do you drive a car that does get full boost till 5000+ rpms
 
#8 ·
sr20damn said:
i know your probably getting tired of responding to me so its ok if these questions gets left hanging....any tricks to making it spool faster?
like polishing things in the turbo or other bullshit
its ballbearing shouldnt it spool at like 1000 rpms or something like that lol?
is there a similar turbo to this one but spools a lil quicker? (BB)

like i said i need a good daily driver but something that would really shock people at the track...you,ve been a big help so far. especially since all this really technical stuff is new to me.
Click to expand...
Practically speaking, the turbo begins to spool as soon as theres a load on the motor, stepping on it in nuetral won't spool a turbo, but from idle in first gear if you stepped on it thats when it starts spooling, it isn't done till 4400 rpm.

No turbo will spool by 1000 rpm. I mean a t25 in a peterbuilt might, but realistically no turbo is spooled by then, ever. You could look into a more responsive turbo if thats what you're interested in, I'm sure theres a turbo that'll get you to 400hp (flywheel) and still spool sooner then 4400rpm. And a 400horsepower sr will rock a lot of ppl's socks at the track, trust me.

Another way to get a turbo to spool faster is to get a twin scroll turbo, those are sick, but that would mean you'd need a new manifold to take advantage of how a twin scroll turbo works, and that could get pretty pricey.
Twin scroll turbos use the exhaust pulse of each cylinder individually to spool the turbo, which means your manifold needs to keep the runners from each port divided all teh way to the turbine.


sr20damn said:
BTW how do you drive a car that does get full boost till 5000+ rpms
Click to expand...
Patiently, thats how. The key is once you're out of first gear to keep the turbo boiling (by keeping the RPMs up), if you drop it and have to spool it up again, thats lost time. Its easy to do in drag racing, harder on a race track. As far as daily driving, its not that bad, it'll just feel like driving a slow ass car untill you put your foot in the motor (step on it).


***EDIT***
Any one feel free to correct me on some of the stuff about twin scroll turbos, because I'm not 110% on some of that, but thats how I understand em to work.
 
Discussion starter · #9 ·
hey thanks...you just taught me about twin scroll. how much do one of those cost?
and you brought up something that i never quite understood, howcome the turbo doesn't spool in nuetral? isnt there exhaust gas spinning the turbine and compressor to make boost?
 
#11 · (Edited)
I haven't ever priced a twin scroll turbo, I know they aren't cheap, lol. Thats something you would have to research on your own, plus don't forget you are going to have to have a custom fabricated manifold which is gonna cost you some cash too, unless theres someone who already makes a manifold for the sr20 like this...(any one know of a shop or tuner)?

I do know that if you get a properly sized ball bearing, twin scroll turbocharger with the right sized compressor and cermaic turbine, with a ported housing....You could make a very healthy bit of power and still spool like a CHAMP.

Also if you cut out a length of your downpipe, and install an electronically controlled exhaust dump, you could run with your stock KA exhaust even, and then when you went to the track or wanted to scare a camaro you could hit a switch and flip open the valve, and that would bring backpressure down to almost zero, which will always help spool a turbo in a hurry.

I can think of one company that makes a product like this in different exhaust diameters called Q-Tech, or something like it.....search for that
 
#13 ·
And a turbo will spool some when in nuetral, if its a responsive enough turbo.

For example: The stock t25 in a second gen DSM will spool up a little bit if you stomp it in nuetral, but the motor is revving so fast that by the time the turbo starts spooling even a little bit your on the limiter and the engine stops trying to make power and sits on the rev limiter. If you could keep the engine at WOT forever and rev till then end of time, the turbo would spool.

But once you hit the limiter the motor either cuts the fuel or spark. And if you try to close the throttle up and hold it at an RPM under that, the motor isn't going spool a turbo at 20 percent throttle.



I never really thought about it before, but thats my guess. Can anyone else think of a different reason?
 
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