Why aren't some concerned about putting a turbo on a high compression motor?

[BRZPDX]

I guess we'll find out. My hopes is not to have my stock engine blow up on me, but if it does, I will rebuild it.

It looks like the stage one bolt on kits are holding up pretty good. Its when people are pushing +350whp (stage 2?) that rear axles, clutch, etc is starting to break. Also heat soak at the track. But this is expected in any modification pushing twice, or three times the factory rated power in any car I believe.

I just tell my self, an engine rebuild is as much as a Disney cruise for 2 people, and a couple nice dinners.

[dabocx]

Originally Posted by dave77

ok thanks for the replies. just was wondering if people were actually aware of this potential issue and what they thought about.

still, what do people think about Subaru lowering the compression on their oem fa20 turbo motor? Why not just do it high compression if it is so safe?

Well one does not go and spend 6k+ without thinking about it, regardless theres alot of people doing fine.

Im still building mine because im getting a bigger setup, just waiting for a stroker kit

[mike the snake]

Originally Posted by RAN94A

This is my next planned power mod

My car is getting finished up this week. FB turbo kit, Element Hydra Standalone and Hydramist methanol injection.

I'm hoping for some decent numbers, but we only have 91 here in CA and I think my shop is going to tune very conservatively to start with.

[RAN94A]

Originally Posted by mike the snake

My car is getting finished up this week. FB turbo kit, Element Hydra Standalone and Hydramist methanol injection.

I'm hoping for some decent numbers, but we only have 91 here in CA and I think my shop is going to tune very conservatively to start with.

are you running a failsafe system?? if so do you mind telling me how you're setting it up?

[wparsons]

Originally Posted by StormTrooper

not sure about the upcoming wrx but the forester dit has been tuned to allow for 87oct aka piss water.

This is why OEM engines are built to different standards than people can get away with in the aftermarket.

If you have a good tuner and know you'll always run good gas you can push an engine a lot further than a manufacturer that has to be sure the engine won't grenade the first time someone fills up with crap 87 octane.

IMO, if you're going to push the engine beyond what the stock internals can take you should build it with stock compression forged internals.

Higher c/r means less boost for the same power. Less boost means less heat from compressing the air.

~20 years ago 11.5:1 c/r was very high for an N/A engine and it required 91 octane +, now you can run 14:1 on 87 octane. DI makes a huge difference.

[dave77]

Did you know that there are random gas stations around Cali where you can buy 100 octane+ race gas? I lived in the bay area for a few months one time, and I found a few gas stations that did that. Was way expensive but awesome. But was annoyed otherwise that there was only 91 octane.

Originally Posted by mike the snake

My car is getting finished up this week. FB turbo kit, Element Hydra Standalone and Hydramist methanol injection.

I'm hoping for some decent numbers, but we only have 91 here in CA and I think my shop is going to tune very conservatively to start with.

[RAN94A]

Originally Posted by dave77

Did you know that there are random gas stations around Cali where you can buy 100 octane+ race gas? I lived in the bay area for a few months one time, and I found a few gas stations that did that. Was way expensive but awesome. But was annoyed otherwise that there was only 91 octane.

Availability is the issue though, whats the point in using race gas if its only available in a select few random service stations.

You've either gotta run dual maps and switch between your regular map and race gas map... or run some kind of Flex fuel set up.

WMI kits are like having your own E85/Racegas additive in your car on tap and it only costs a couple of extra $$'s per fill up if you work out how much you pay for the Methanol.

[dave77]

Yea for sure, just wanted to mention it. I love how some regular gas stations have a "race gas" pump.

[DeliciousTuning]

High compression and boost is good. Been tuning these setups on Subaru STI's for years. On stock NA engines 10.0:1 ( stock turbo engines are usually 8.1:1 or so). Even built engines up to 11:1 with 27 PSI of boost on 91 California pump gas. It is not so much direct injection but airflow in and out of the engine. The more efficient the flow the more boost and timing you can run on 91 pump gas with a less likely chance of detonation.

So far we have hit 500whp on an STI with high compression, 27 PSI of boost and 91 octane. Airflow efficiency is key and the FA20 engine is pretty damn good.

Cheers,
William Knose