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compression and turbo?

1798 Views 11 Replies 8 Participants Last post by  TheBlade
ive been researching getting a turbo for my egt for a while and was wondering if anyone knows what is better high or low compression on a turbod vehicle and why,
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Sorry I´m so slow on replying to this one.

Your mazda BPD8 has forged internals. Try to beat that with any honda motor.

I know for a fact you can safely run 10psi on the motor. However I´m going for 14psi on the track with turbo-blue fuel and a whole lot of timing retard.

The compression ratio of the BPD is 9.0:1 so, on 14psi you´re at 14.02:1 compression ratio. For a gasoline motor that can be dangerous territory.

The GTX motor is 8.2:1 so you can run 14 on pump gas no prob with timing control.

On extremes I´ve heard of some motors running a ratio of 7.0:1 and then running like 30-35psi of boost. Not much go off the line, but once its boosted.....just think average gain of boost is 8-15HP for every 1psi.
Skuce I dont know what the 1.9 can handle, but I had a roommate with a D16Y8 Honda motor. Its a SOHC motor that doesn´t have forged internals and he was running .54BAR of boost.

Usually turbo´ing over 100k isn´t good...I know I´m a hypocrit. I was officially boosted at 98,800miles. I´m at 101,900miles now.
Okay man here goes:

I got my turbo on eBay, but I know its going to need a rebuild in 20k miles or so easy. If you want to spend the money on a rebuilt one that´s like brand new check out turbocity. The company is based in Anaheim SoCal. They do great work there.

I´m running my turbo in the winter, but its Northern AZ. When it snows it doesn´t last more then a day or so, and the night time temps usually hit 15 degrees F, I guess that´s like -10C for you Canadian folk. The only thing I´m worried about is my oil. I´m running 15w50 Mobil 1 synthetic right now. 15 weight oil is supposed to be okay for below freezing, but not that good for it. But if I drive to Phx when its 80 in winter, I can´t have something too light in the motor.

Okay GTX and stuff, I turbo´d my BPD. Its a 9.0:1 compression. With my motor turbo´d I´ll have a little better response on the low end, but not nearly the top end the GTX motor gets. The GTX is 8.2:1 compression ratio. I feel the slightly higher compression will help me be a little more "streatable," okay so I didn´t have the money to get the GTX. Anyhow I plan to run 8psi -10psi on the street. I am pretty confidant that I can get 14psi on the track with 114 octane fuel and timing retard. I know Orlando, Denis, and Adam are running the GTX motor. Orlando, as far as I know is somewhere around 10psi, Denis I think is up around 18psi with a non IHI turbo (TD04 I think), and Adam is running 26psi on the IHI VJ23 ball bearing turbo. All three of them did it the right way and spent the money on a Haltech E6K that can do everything.

All are really impressive. Orlando has the ultimate sleeper, looks pretty stock from outside. Denis´ looks so clean, and its an automatic! Adams is total show, custom paint --> everything.

Either way you go its a journey that never ends. You´ll always be doing something to your EGT.
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