Nozzles or turbo maxed out.

[Twan]

Trying to figure out if I have maxed out the turbo or my nozzles.

I have a powermax with single plain wheel and 75/30% injectors.

On my big tow file locked in overdrive I get 35 psi boost by 1700 and it drops off after 2500 rpms, it will drop to 26 by 3000 rpms. Egts will hold 1300 from 1700-2400 then start to climb, up to 1600. It's smoke free too.

Not sure if the nozzles are to small to push the turbo or if I don't have enough turbo to push air up top.

What do you'll think?

 

[turbie]

sounds like not enough air. but if that was the case, I would think it was start smoking. and your egt's would then go up. That's a hard one. it could be either in my opinion. If it wasn't enough injector, I would think it would clean up but not have high egt's.

 

[FaSSt9602]

Not enough turbo would be my guess, but it could depend a lot on your tune. Obviously a tow tune isn't going to come close to maxing out those injectors. The 30 over nozzles can empty a 175 barrel on a full race tune. If anything, those nozzles might be TOO BIG if all you plan on doing is running a small pulse width tow tune.

 

[sootie]

sounds like not enough air. but if that was the case, I would think it was start smoking. and your egt's would then go up. That's a hard one. it could be either in my opinion. If it wasn't enough injector, I would think it would clean up but not have high egt's.

true...except if he is running gearhead tunes which wont fuel it if is doesn't see boost-therefore no smoke.

 

[Twan]

This is on my DP tow with atlas 80.

I need to get new gear head tunes still.

 

[Twan]

Going to get the ported manifold on then late this summer going up to bigger nozzles.

At least that's the plain, then I'm sure a bigger turbo. Lol

 

[KCTurbos]

Trying to figure out if I have maxed out the turbo or my nozzles.

I have a powermax with single plain wheel and 75/30% injectors.

On my big tow file locked in overdrive I get 35 psi boost by 1700 and it drops off after 2500 rpms, it will drop to 26 by 3000 rpms. Egts will hold 1300 from 1700-2400 then start to climb, up to 1600. It's smoke free too.

Not sure if the nozzles are to small to push the turbo or if I don't have enough turbo to push air up top.

What do you'll think?

35psi by 1700rpms? That seems a little crazy. Was that with a big load hooked up and rolling into it at really low rpms? That is pretty far off the comp map and would usually result in surging???


Are you running a tow file? The easy way to check if you want more fuel is to just run a race tune.


IMO atlas 80 + a good tow tune... is just going to run like a crappy race tune.


A good cool, clean running truck needs as much injection pressure as possible, that helps the truck to run cooler, cleaner, and spool the turbo better. Running more advanced timing will also help to cool off your egts and bring up turbo boost... but most tow tunes run very conservative timing. Running the atlas 80 will bump up the PW which means that for the same amount of fuel... you will have lower injection pressure.


running the atlas 80 with a tow tune is like having the worst of both worlds... low injection (because of the longer PW) and non-aggressive timing (because of the tow tune).


Most people have issues running even atlas 40 on a race tune... I recommend the econo tune for towing and really clean running trucks.

 

[Twan]

That's with or without a load on it. It's smooth power, has a ton of low end power with that combo. I normally run the tow and atlas 40.

It's the only combo I hane found that has power in the 1700-2000 range. Keeps all the temps low. Egt, water, oil and tranny.

 

[Twan]

This was at 2000 rpms tow file and atlas 40 pulling 9000 lbs up a hill.

 

[KCTurbos]

View attachment 35887

This was at 2000 rpms tow file and atlas 40 pulling 9000 lbs up a hill.

Cool. 30psi at 2000rpms pulling a big load up a hill is normal... but 35psi at 1700rpms did not sound right (especially if that was with no load)

 

[KCTurbos]

Do you know what ICPv you are seeing at WOT?
What about EBP and VGT duty cycle?


You could be dropping off ICP (either from too much PW or weak pump). That will cause egts to go up and boost to go down at higher RPMs

Also, you might need a more aggressive VGT duty cycle in the higher rpms band. If it is opening the vanes too much too soon the boost will drop fast in the higher RPM band.

 

[Twan]

My bad on boost, with the atlas 80 it is 30 psi at 1700 and 35 at 2000

Not volt but I see 3900 psi at wot. Think I have 2800 psi at 2000 rpm.

Back pressure is 38 psi.

 

[KCTurbos]

My bad on boost, with the atlas 80 it is 30 psi at 1700 and 35 at 2000

Not volt but I see 3900 psi at wot. Think I have 2800 psi at 2000 rpm.

Back pressure is 38 psi.

Those all sound pretty healthy. DO you have a mechanical ebp gauge? I dont think the pcm can read past 38 or 39.


Do you know what your PW is at WOT?
Do you know what VGT duty cycle is at WOT at higher rpms?


You could have your tuner add a little timing up top, that should help cool egts a little bit.

 

[Twan]

I'm using the edge, I do not know what the pw is at. Can the edge read that?

I will check the Vgt duty this week some time.

I will also look at the back pressure again. I did wounded if it was maxing the sensor out, but for some reason I thought it would bounce 37-38 psi.

 

[swinky]

Where is your boost gauge tapped into?

 

[Twan]

It's in the intake horn.