Are you daily driving your car running higher boost?, How is the driveability? (gas mileage, such and such), and what else are you doing, or planning on doing to maintain the reliability. I would like to know bacause I would like to go the FI route on a daily driver, but I am stuck on if I want to go higher then the stock boost level or not. My considerations are the APS, Greddy, Vortech, and HKS systems. Thank you in advance.

 

Running 8psi daily, no problems, gas mileage is fine... very driveable... just dont floor it all the time if you don't want the boost.

 

The kits are all extremely driveable, even at higher boost levels. The TT's have slightly better fuel mileage, since they are not using the crank to drive the blower. I can still get 20mpg with my TT at 9si, with occasional WOT blasts.

To improve reliability, perfect tuning is a must, as are some fuel upgrades for higher boost levels with the Greddy kit.

Forged internals are also a good idea. See my group buy.

 

I did a trip to Nashville (6hr drive one way) and averaged about 23.5 mpg with Vortech tuned to 420rwhp.

With a more typical mix of around town and highway miles, I usually log in right at 20mpg

 

Note for those adding lower CR forged internals there is a "price" for the added reliablity. With an 8.5:1 CR "off boost" gas mileage will be notably lower than with the OEM 10.3:1. I accept this trade off , yes and I know I'll **** off a tree hugger or 2

 

How will a 8.5:1 piston have poorer gas mileage then a 10.3:1?

 

Higher CR equates to higher volumetric efficiency, which equates to better MPG given equivalent loads. So you loose volumetric efficency under "off-boost" conditions and you gain volumetric efficiency and "then some" when "on-boost" , but this gain is to create more power , not MPG.

You will note that over the last few years CR has been creeping back up on OEM NA cars. This has happened because it improves MPG and combustion chamber technology, timing and fuel control have evolved to do so while safely operating without detonation.

 

Damn..you are so smart...and absolutely correct. BMW has mastered the concept of direct injection, where the fuel is injected directly into the combustion chamber instead of the intake track. In doing so, they get exceptionally low emissions, and are able to increase static compression to almost 11.5:1. Audi is doing the same thing in the A8. Don't quote me on the actual compression ratios....my point is the higher compression ratios equal better power, fuel economy, less emmisions.

 

Both you guys are smart.

I think i read some where that Audi's direct cylinder injection allows them to use 12.5:1 comp ratio on pump gas.

The 07 GT-R will have this technology too!