Kinds of Turbos

[bradNSX]

My friend has a Greddy T 78 on his 1994 RX7 which looks about the same size I am seeing on some NSX's. They were putting out between 15 and 20 pounds of boost...which is what the T 78 does as well.

I am interested in learning more about turbo's and which one is the best for the NSX.

If you have a turbo on your NSX, what kind do you have, how much does it cost, and how much boost will it give?

 

[NSXTASY_MD]

My friend has a Greddy T 78 on his 1994 RX7 which looks about the same size I am seeing on some NSX's. They were putting out between 15 and 20 pounds of boost...which is what the T 78 does as well...

NSX's with a Greddy T78 turbo ?? I don't recall ever hearing about one on this forum at least.

I don't think that would be a good turbo to choose for an NSX turbo kit anyhow...as it's a little too big for most applications (short of drag racing) and has relatively poor spool up qualities compared to other hybrid turbos on the market these days.

 

[sjs]

Turbo selection is actually fairly complex and there is much you can't tell from the physical "size". A given set of housing "halves" can contain a variety of different specification turbines/impellers for the exhaust and pressure sides. It is also important to know that a more meaningful measure than boost is CFM (Cubic Feet per Minute) because of course a large displacement engine requires more CFM (“bigger” turbo) to achieve the same boost as a smaller engine. (The math is a bit less direct when comparing a Wankle to a normal piston engine, but you get the idea.)

The key to selecting the right turbo for a given engine is reading and understanding the compressor maps published by (most) manufacturers, and then probably a bit of final trial & error. Anything else is a guess and likely to yield poor results, such as high intake temps, poor efficiency, slow spool-up, etc.

Not the answer you wanted of course, but no sense making it sound simple when it is anything but.

 

[winreboot]

Yes, everything is in the calculations/compressor maps.

Here is a link to turbo calculator http://www.turbofast.com.au/TFmatch.html

Myself I have turbonetics T3/T4 .63ar turbine, 57T compressor wheel .50ar compressor housing. I know some guys here are running little bigger then this on their setups.

 

[NSXTASY_MD]

Yes, everything is in the calculations/compressor maps.

Here is a link to turbo calculator http://www.turbofast.com.au/TFmatch.html

Myself I have turbonetics T3/T4 .63ar turbine, 57T compressor wheel .50ar compressor housing. I know some guys here are running little bigger then this on their setups.

Thats very interesting...how's spool-up on your kit ? When [rpm] can you get your max boost ? What boost are you running now, is it holding to redline fine ?

...I'm about to jump into custom, intercooled single turbo kit myself and I'm still in the turbo selection phase. I'm looking for good spool characterists and all I need up top is a turbo that can easily hold 10-12 PSI to redline on the NSX 8K redline motor, thru an intercooler. (My street boost setting would be no more than 8psi)

...could I possibly PM you with some more questions or even see your set-up sometime...I'm not too far from Jersey

 

[Ryanmcd2]

That turbomatch site is great, It said gt30 for my car at 34psi and that's what I was looking at

 

[winreboot]

Thats very interesting...how's spool-up on your kit ? When [rpm] can you get your max boost ? What boost are you running now, is it holding to redline fine ?

...I'm about to jump into custom, intercooled single turbo kit myself and I'm still in the turbo selection phase. I'm looking for good spool characterists and all I need up top is a turbo that can easily hold 10-12 PSI to redline on the NSX 8K redline motor, thru an intercooler. (My street boost setting would be no more than 8psi)

...could I possibly PM you with some more questions or even see your set-up sometime...I'm not too far from Jersey

Spools-up to 6PSI around 2,500rpm's. I did not drive the car hard after I went with AEM and now I'm waiting to get tunned on dyno this weekend. But it spools up very quick, little tap on acceleraton when crusing around 3000rpm's and whooosh it is instant boost. I just hear the Delta wastegate doing it's job. Before AEM it was holding boost very good. Now I'm controlling boost with AEM want to run like 7psi.

Sure, PM me if you have any questions or want to pass by after this weekend

 

[winreboot]

I forgot to add. In my opinion the piping to turbine should be 2" or 2.25" and down pipe 3" Since turbine is so far from the headers having big "Y" junction with 2.5" piping will need to create back pressure before the compressor wheel starts creating boost.

This makes bigger turbos will not spin on IDLE. You will see exhaust smoke coming out from the exhaust pipe but if you will look at the turbine it will not spin untill you will rev the engine. This is what I seen. When turbine is very close to headers it responds very fast. The farther the "Y" junction is the more lag. So the power band moves to higher rpms.

 

[Sig]

Spools-up to 6PSI around 2,500rpm's. I did not drive the car hard after I went with AEM and now I'm waiting to get tunned on dyno this weekend.

6psi at 2500rpms, that's great!

Keep us updated on your tuning this weekend, I am curious to see what kind of numbers your making at that boost level.

 

[NA1/2-R GT]

6psi at 2500rpms, that's great!

Keep us updated on your tuning this weekend, I am curious to see what kind of numbers your making at that boost level.

wow, that means you have full boost the second you step on the gas? I believe at the point of clutch release you are most likely on 2k-2500 RPMs. That's kinda quick if you ask me... hard to believe but maybe doable.

At idle and your turbo is not spinning? hmmm looks like you need ballbearing turbo... or that turbo is not free enough.

 

[SpeedDemon]

A quick general tip for everyone, when hearing or asking about boost built at a particular rpm:

The info is near meaningless if you don't also ask what gear the car is in.

You'll find that even larger, laggy turbos can put out decent boost at low RPM's if you run them in a higher gear (ie, on the freeway, cruising at 60mph in 6th gear). There's tons of load put on the engine in such a scenario.

Results are typically different when you look at where full boost comes on in 1st & 2nd gear.

Marc
'04 Noble GTO 3R
(Sold) '97 NSX Twin-Turbo

 

[NetViper]

Marc
'04 Noble GTO 3R
(Sold) '97 NSX Twin-Turbo

Marc,

How do you like your noble? I saw it at FX while I was there. What engine did you end up with? PM me if you want..