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7.4:1 vs 8.5:1 cr decision


onephatz

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Turbos are different than superchargers. As you know' date=' superchargers get energized from a belt drive and turbos get power from the exhaust. So it makes sense that they would have different cam requirements. And turbo don't like to scavenge.

 

The reason is the pressure in the turbo exhaust manifold can be as high as 35 psi! As compared to the exhaust on a supercharged engine which is like 4 or 5 psi when exiting through headers. So if there is ANY overlap on a turbo it causes exhaust to enter the intake. Therefore, bigger intake duration and smaller exhaust duration is the best setup. The small exhaust duration helps keep the "zero" overlap and increases exhaust velocity, just what a turbo likes.

 

I'm pretty sure Talons and Eclipes use the T3 with a 0.48 housing.[/quote']

 

I see says the blind man! I was assuming that since blowers and turbos both provide positive pressure the idea was interchangeable.

 

fyi. 90-94 dsm's use a mistbishi heavy industries 14b and 95-99 dsm's use a garrett t25. they both have the same exhaust housing but the compressor wheels and housings are not the same. I have two t-25's off a '95 eclipse.

 

anyways

 

thanks for the info

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The problem is, the t25 (or t-too-small) as the DSM world likes to call it, only makes about 250whp @ 15psi, which is pretty much maxed out. Running this for very long will burn up the bearings with in a year or so. which is why everyone gets rid of them.

 

FYI, the t25 and 14b are completly different turbos, nothing about them is the same.

 

The t25 is a Garrett produced turbo, and the TD05-14b is made my Mitsubishi.

 

The t25 has a power output of about 250whp.

The 14b has a power output of about 280whp.

 

This of course varies with many things. However it's average.

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Guest Zcarsmakemyheadhurt

The other bad thing about a T25 is the shaft size, too damn thin. Push those turbos around too much on a big motor and they go quick.

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