a question about turbos

[tailgatewagon]

what do you think would happen to performance if i added 3 feet more of exhost pipe before the turbo. or if the turbo were mounted to the head so there was no header??? im talking about performance only not logistics or routing or any of that. thanks

brian

[calebz]

In either scenario, you would probably lose performance.. mounting directly to the head would mean you were only getting exhaust pressure from one side, instead of both.. that would make for slower spool up and less air getting pushed back into the intake.. adding 3 feet of pipe before the turbo, would also equal less pressure going in, which would mean less pressure going out

[Snowman]

I know that putting the turbo closer to the exhaust ports on the engine will make it spool up faster. If you could somehow mount twin turbos, one on each head, they would spool up really fast if you sized them appropriately to account for there being two instead of one. I don't know enough about the ea82T to make any guesses as to what you would have to do to the size of the turbos. Adding exhaust pipe will decrease the performance because it will take longer to build up pressure, and a lot of the benefit of the thermal gas-expansion stuff will be lost. That said, it apparently is beneficial to run pipes that are of equal length from all the cylinders so that everything is equal.

[asavage]

Originally posted by tailgatewagon

what do you think would happen to performance if i added 3 feet more of exhost pipe before the turbo

One problem of extending the head-to-turbo distance is gas contraction. All of that additional pipe is shedding heat, contracting the gases within it, meaning that you throw away energy that could potentially be used to spin the turbo.

 

IOW, you'd want really, really good insulation on the turbo feed pipe. If you could acheive very low heat loss on that pipe, you would likely notice very little difference in performance -- there'd be some, but it would be small. If the heat can be retained, then the same volume of gases coming out of the head will be entering the turbo.

 

The turbine section of a turbo exchanges hot, high velocity gases for cooler, lower velocity gases + mechanical shaft rotation. Take away some of the heat, and you lose velocity too.

[subarubrat]

The runs from the headers to the turbos on my XT6 (EG33 powered) were about a foot long, just enough to get the turbo behind the heads. It worked perfectly but again, that is a twin turbo setup, with a single, you want something like the stock header. Even Sam Rigoli uses the stock header on some of his 9 second cars.