Can't get any more boost from stock turbo

[charlief1]

Will do Jesse.

 

[marleyskater420]

Well there are a few things that are happening, but to make it short, you need to free up as much backpressure as possible to help that small turbo sing. A 52mm turbo trying to fill up a 231ci engine at 5200rpm is a tough feat, getting as much of the compressor map back is SUPER important.

So, start freeing up inlet backpressure like ditching the stock MAF, Intercooler, and TB/Plenum. The stock intercooler alone is killing 5psi off the compressor map, add 3psi more for the stock MAF and you can see why everyone always shows low 20's psi in 3rd with the stock turbo and parts. Going mafless or Z06 maf and 3" inlet pipe will help right there 3 to 2.5psi.

Go E85, Alky and no intercooler and start seeing 30psi!!!!:biggrin:

Can you explain this a bit more please?

So are you saying it can't get past 20psi because it is so restricted in airflow coming towards the turbo (compressor side) that it doesn't have enough flow to create more than 20psi?

Or is it that these restrictions cause the flow to the turbo to be much hotter, which in turn lessens the efficiency of the turbo, and therefor it needs to spin faster to create the same pressure? Which is why if he frees up the restrictions, the turbo does less work to create the same pressure, so his 20psi is now 23psi at the same WG setting?

Any feedback is appreciated. Thanks!

 

[usetaboost]

i'm thinking it had to do with the solenoid bleeding off too much not allowing any more boost. For the most part you are right about freeing up restrictions. That's why most people do the maf pipe and cone filter and exhaust right away, after a good chip and spring cleaning of course

 

[charlief1]

Sorry Jesse. Cooler's gone. I'd bet he got 50 cents a pound for it. My ex-boss the genious.

 

[GNVYUS 1]

To talk about the backpressure side of things.

To simplify things, the stock intercooler eats up about 5.5 pounds of boost due to poor core pressure drop. This means when you see 20psi at the manifold, the turbo is really pushing 25.5psi. The extra 5.5psi is heat the intercooler has to deal with, and the stock core is not so great.

Now add on the other things that create backpressure, there are a TON. The Maf, inlet pipe and intercooler are the easiest on the inlet side. The compressor housing itself helps here and is generally overlooked, but that's why the TA49 has less output than the TE44, the comp housings are different. That restrictive inlet bell on the TA housing causes some restriction on the top end of the comp map vs the TE's opening which is usually a straight 3" to the housing. Hell, my 91 Talon has the 4" opening and was rated 10-15hp more than the 3" opening. :biggrin:

Anyways, if the stock turbo guys ditched the intercooler all together (I have) you'd see an instant 5psi gain on the boost gauge, yet the turbo isn't actually pushing more boost than before. So now you're cylinders have a higher compression ratio, so add more fuel and now MORE POWER. Nice!!!!

So open up those restrictions stock turbo guys, and watch that little Vidal Sassoon hair dryer roar. :wink:

To give you a real world case, there is a DSM tuner named Lucas English that has a tiny EVOIII 16g turbo (48mm), he ditched the intercooler and with E85 and tons of Meth he was able to hold 30psi at 8k rpm to the time of 10.6. That's a smaller turbo, on a car with bigger heads to a higher rpm. Now to be fair, it needs a slightly lower CFM requirement since it's a 2.0L, but that turbo is 48mm vs our 52mm and has a WAY smaller exhaust housing.

 

[usetaboost]

I'm gonna try getting some info on the isuzu npr box truck intercooler and see if those are any good. If anything to will be easier to plumb and should have to hack much if anything.

 

[S2V6RACER]

From what I've gathered the stock intercooler is garbage no matter what way you cut it. Wish I had money for a cotton's front mount IC or another equivilant 1000 dollar IC

I don't think you need to spend $1000.00 for a front mount to get the performance you need.

Give Cal Hartline, or Full Throttle a call, I'm sure they can save you some $$.

 

[coach]

I ran into the same thing. I changed downpipes and ran 24+ for the entire summer until I went with my 49. Dutt neck cooler too.

:biggrin:

 

[usetaboost]

The actuator just wasn't up to the task. I put on a mbc and now I'm running a consistent 22psi with no spike or creep. I could run more boost but I think it pumps too much heat after that boost.

 

[charlief1]

Glad to hear it Jesse.