Audi S3 and Mercedes CLA45 AMG

[mkarch]

If you want something that drives well, you should at least try the M235i. I can't imagine either of the FWD-derived merc/audis with 60/40 weight distribution can achieve the same feel you get in a BMW. The reviews are good on the CLA45 so far, but I've yet to see a comprehensive head to head test of the production models.

[Malloric]

Originally Posted by MckinneyOwnr

27 psi is 27 psi, regardless of what size turbo you use, there is no difference.

In what?

In psi, no. In amount of 02 entering the engine? Absolutely there's a difference. Lower inlet temperature from a larger turbo for the same CFM flow at a given pressure means much denser air, less back pressure, velocity of air in the intake manifold.

You're not really comparing 27 psi between a large turbo and a pea-sized one. You're comparing 27 psi on a pea-sized turbo (very high inlet temperatures) to maybe 16-18 psi on a larger turbo. If they have the same flow rate, velocity through the intake is faster due to less back pressure. Plus the air is denser (cooler), so you're getting more 02 for the same flow rate at lower pressure. If you had a hypothetical engine with sufficient injector size hooked up to a pure 02 hose at its inlet it would make much more power at ambient pressure than any turbocharger boosting to 27 psi.

Your engine isn't really going to complain about 27 psi. I mean, it's compressing it by 9:1 or so anyway. What it won't like is heat. Heat leads to predetonation and then the ECU retards the timing. And then there's stressors from combustion which has to do with how much O2 there is, not so much the pressure it went in at.

[Malloric]

Originally Posted by vision33r

You can't compare a factory turbo car with an engine specifically designed to handle turbo pressure against a car with a factory NA engine. If you turbo a NA engine, you will blow the engine eventually because it's not designed to handle that much pressure.

I trust a turbo engine over a NA engine in terms of longevity because those turbo engines are designed and overly built to withstand a lot more abuse than a typical NA engine.

EJ20 and EJ25 are all NA engines with turbos added onto them. They weren't specifically designed to handle turbos, just modified to.

[MckinneyOwnr]

Originally Posted by Malloric

In what?

In psi, no. In volume of air pushed into the engine and resultant effective compression? I hope you're not that ignorant. That's really basic high school level physics, flow rate and pressure. There's absolutely a difference.

You clearly have no idea how turbos work. Go read a book before calling someone ignorant.

27 psi from a small turbo is the same as 27 psi from a larger turbo.

[MckinneyOwnr]

Malloric, nice edit.

You still have no idea what you're talking about.