the higher PSI you run, the lower compression ratio you wanna run. that way you don´t end up blowing your engine apart. ask Blade. he knows alllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll about turbo´ing scorts. yes, all that all, he knows it all. kinda like the commercial.
Lower compression is better for a turbo motor, but the higher compression will make more hp on the same boost. Using lower compression you theoretically can push more boost. Say you had two engines, one with 8.0:1 compression and one with 9.5:1 compression. Of course the higher compression one would make more power with the same boost (say 15psi). But say the 9.5:1 engine can only handle 15psi, but the 8.0:1 can take 25psi or more. Then the lower compression engine would most likely net you more power with more boost. So bascially they are both usable it just depends on what you wanna do with it. Also remember the lower compression engine will be sloooow before you hit boost. I know this first hand from my 323 turbo which has a whopping (lol) 7.9:1 compression ratio.
I´ve heard the stock 1.8L will handle 14 psi boost (basically doubling atmospheric pressure) on stock internals. I know I could get 30 psi out of my car, rebuilt of course. thats over 3 times the atmospheric pressure.
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.
Where is the best place to purchase a turbo from? Second any of you guys running turbo's in winter? Also are you guys running on a stock engine or GTX (what kinda boost), has anyone had a GTX shipped to Canada. One last questions what are the Stock ponies on a GTX. I think question period is over..
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.