Evil Aviator

First of all, the rpm in the formula is 5252, not 5250. However, this is a minor error that does not have a significant impact on the outcome. The main problem is that you calculated the torque at the peak hp rpm as if it were supposed to be the peak torque. I guess you could consider it more of a correlation error, but it does result in a math error. The bottom line is that you can't use the peak hp to solve for peak torque unless peak hp just happens to occur at 5252 rpm.

You made the same mistake with the "sweet spot". If you don't understand the error in mathematical or theoretical terms, you can spend some time and look at various hp/torque dyno numbers. You will see how the peak torque moves up and down the rpm scale with changes in porting and boost, even if the intake manifold remains the same.

I guess that's some cultural difference that I don't understand. Personally, I wouldn't go on an international internet forum and accuse any of my friends of false advertising.

FDNewbie

iTrader: (10)

Evil, do you think you can do this newb a HUGE favor and tell me if there's a trend here? AFAIK, larger ports = moving the torque curve higher up the rpm scale, right? I'm not quite sure what you mean by boost...ie spool-up time, or the amount of boost you're running. I know that larger turbos require larger spool-up, and I'd imagine that a larger port = greater airflow = lower spool-up time, right? If you mean the amount of boost you're running, I don't know what correlation there is between it and torque and rpm...

Thanks

Evil Aviator

A huge simplification of a very complicated issue:

The cross-sectional area of a hole has an optimal volumetric airflow rate. A lower airflow rate will lose momentum, and a higher airflow rate will incur more drag. Larger holes will have a higher target airflow rate. The efficiency at which the air flows through the ports will have an effect on torque.

Another simplification that isn’t exactly correct in technical terms, but should give you the main idea:

Boost adds more air to the combustion process. Along with the additional fuel injected, this makes a “bigger fire”, which increases the combustion pressure, which in turn increases the torque applied to the output shaft. The amount of boost at a given rpm will increase the torque at that point. Therefore, it is possible for boost to change the peak torque point in the torque curve, depending on the amount of boost and the rpm at which it occurs.

If you want a visual, imagine an NA engine that produces its peak torque at 3,500 rpm. Now add a turbo with a really small turbine wheel so that boost is created well below 3,500 rpm, but the turbo runs out of boost very quickly. The peak torque would most likely move lower than 3,500 rpm. Now replace that turbo with a huge turbo that doesn’t even produce boost until after 3,500 rpm, but produces an insane amount of boost after that. The peak torque would most likely move higher than 3,500 rpm.

FDNewbie

iTrader: (10)

Thank you very much