Turbo Discussions (split from Beyond Dyno Day in Spring 2003)

[Maxt]

The real trick is to get a turbo that is capable of supplying the airflow you want at the psi you want, without thrashing the air to shit, stock small turbo's overspeed at higher boost levels, the resulting turbulence heats the air, and lessens the density, negating the effect of boost, a good intercooler will help with density recovery, and as we all should no by now density=power, more air means more 02, with more fuel equals more power...
If Chrisng could post his dyno sheet , I could post mine and show exactly the difference in a large turbo and good intercooler on basically the same car, at 4500 rpm his turbo starts to run out of airflow, and starts to heat the air, also his intercooler stops being an intercooler, his power starts to peak out and drop, although we have the same car, I continue on with another 110 hp for another 2000 rpm...
You can push 15 psi on a stock turbo, however you will probably make less power than you did at 10 or 12 psi, and cook your motor at the same time..
Psi does matter,but only if have a turbo that can remain above 70 percent efficiency while doing it.. My motor grenaded at 17 psi of boost, but my turbo is good to 22 psi on my motor, which incidently did not detonate upon further inspection, 1 apex seal simply folded over in the rotor groove, probably due to loose clearance than anything else..Maxt

[drox]

Werent you running a full to4 turbo and chris using a hybrid pf the stock turbo? And does he have a fmic? I never really noticed.

[Hollywood]

Originally posted by ConVict
And earlier hollywood when I said it would clog your exhaust I meant in the long run from carbon deposits and stuff... I may be wrong

Yes you are wrong but it's OK were getting used to it.

[James]

Originally posted by Hollywood


Yes you are wrong but it's OK were getting used to it.

lol

[ConVict]

Then why did I see some ones post saying that Rally cars make there turbo keep on spinning and keep on pushing the air and fuel into the exhaust and bypass's the engine so they dont recieve turbo lag... then some one responded they have to replace there exhaust every race ?!?!

[drox]

Because on a rally car the chances of the exhaust getting crushed from shit while they are running a rally is really, really good But I never heard any of that before.

[Maxt]

Rally cars use anti lag, which is basically retard the timing into last week, and blow through copius amounts of fuel the result is the exhaust port turns into a blow torch, which keeps the turbo spooled, the bad news is that it destroys the turbine wheels..
I have the anti lag option in my car on my haltech, but I have no incentive to start melting turbo's, although I have now hooked up my flat shift switch, so I can hold the gas to the floor at launch and during shifts and not rev over 5000 rpm while the clutch is pushed in, its gonna make launching the car pretty violent...Maxt

[Toma]

Yeah, I tried that with my ECU, and man did the car get up and go ina big hurry. It was as responsive as a blower car....VIOLENT. But I could cook a steak on my hood afterward.

I heard there are some EFI systems now that only activate anti-lag on shifts, and hi-rpm transient throttle conditions...but we are now talking $$$ cause the system I saw can be tuned from the pits by the pit crew while the care is racing!!! Coooooool

Toma

[ninspeed]

go to a probe site and ask the guys if they have any flowmaps of your turbo on your engine... it will help you with finding the proper amount of boost to run.. why run 30 psi if the air is flowing 10x hotter, thus less dence than 15-20 when the air is cooler and thus more dence, which means more air to make your clamied 600whp

[MaEsTr0]

A VERY simple way to explain the whole situation we have here is this:

take a tire, mounted on a wheel, and fill it up with air. Lets say is a 195/55R14, and set it at 40psi

Now we'll take a different tire, eg a 245/75/16, and mount it and fill it with air, and set it at 35psi

the first tire may have more pressure, but the second one contains more air.

This is just a very very basic way of explaining this concept.

for some good info, check out the technical setion of stealth316.com

I also suggest reading Maximum Boost by Corky Bell, and Turbochargers by Hugh Macginnus(sp?)

I havent been able to locate a compressor map for the turbo probes yet BTW. I believe its an IHI unit

[legendboy]

My turbo can make 30+ psi hehehe and it flows over 60lbs/min.....but I'd never try to put stock sleeves-pistons-rods..etc.. through that...not that this has anything to do with your thread