g/4 cylinders charge = 120 * maf (g/sec) / rpm (rev/min) <-- Just as an FYI. That's the fomula used by the Denso ECU's and the SSM (Subaru Select Monitor) protocol, to calculate engine load.

Jorge (RiftsWRX)
www.ProjectWRX.com

 

Mr. Banks!

Nice to see you chap!

Glad to see some familiar faces around here.

Jorge (RiftsWRX)
www.ProjectWRX.com

 

This is the kind of info we need!!!

It would be AWESOME to have the load formula for the Evo ECUs. Anyone???

 

Peak #'s do appear low, but that really mean the car isn't fast. It allready makes 200WHP at 3400rpm and has a fatass amount of area underneath.

I bet the car is fast as hell, but the only way to really tell is MPH at the track

 

Rod bearing stress from cylinder psi from timing or detonation? Would you expect same response with this car in regard to timing on 93 with methanol?

 

If I understand the question properly, it be from cylinder pressure.

Technically.... a cylinder makes PEAK pressure at TDC. Obviously, at TDC you have ZERO mechanical advantage. So the key is to try and light off the mixture soon enough BTDC to impart maximum push.

Too much cylinder pressure (taking octane out of the equation for a minute) cause blowouts of spark, crushed rod bearings (think hydrolocking), rods, crowns, etc.

Thus why I've always focused on area under the curve and consistency, not that last HP.

Jorge (RiftsWRX)
www.ProjectWRX.com

 

I'm thinking of the painfull belly flop I did showing off to my kids at the pool the other day.
Some trap speeds I bet will really put this in perspective. EMR8 -got a helmet?

Thanks for the insight

 

Only problem is that the qualification tools others would use to justify a good tune are very subjective.

Some may cite trap speed, some may cite a 1320' time. Others still a HP number.

Frankly, for me those are subjective.

Trap speed, while a good indicator of power, is still up to the individual.

Case in point.

One of my good friends and Subaru clients has a 2.0 WRX with a JDM swaped STI RA-C engine, and an HKS 2540 turbo kit. Made about 405 WHP on C-16. Car good for the 11's.

At our last shoot out, he was NOT on his game and didn't get the launch control dialed in until about his 4th run.

Ironically, even though the car didn't change, he went from 12.3 at like 112, to 11.8 @ 119.

Clearly, if you use his "poor" runs as a metric, at 112 MPH and 12.3, one would imagine (to put it frankly) that his car sucks.

Same tune, same driver, better run. Now he's running 119. Something you'd expect from a car with 400WHP.

Dyno's you obviously can't compare, so that's out.

That really only leave consistency.

I never shut my cars off, they get run HOT, over and over and over. Those graphs (as you saw with the OP's) lay right on top of each other (boiling hot), and no matter how many times I do it, they'll continue to do that.

THAT, for me, is the metric of a good tune. Next time you guys are getting dyno tuned. Challange your tuner to do THAT with you car... when he says he's done with it of course...maybe a minute or two between runs.

I can cool down a car, and jack everything up and make 15 more HP... but what favor have I done you if it's knocked itself right back down on the 2nd run?

I tell my customers that a dyno is a tool. Curves and trends are what matter to me. If it happens to produce a hard-on inducing number in the process... so be it.

Jorge (RiftsWRX)
www.ProjectWRX.com

 

I happen to totally agree with you Jorge, I've been tuning that way for years.. I've always openly stated that the power under the curve, and a cars drivability are way more important than a one-time money shot, good for the tuner, and for the "Mechanical ****" but useless in real life.

I rarely tune on the dyno, unless I need to make consistent back to back runs through the RPM range to get the initial tune dialed in.. Most of my tuning is done on the street, using logging, while the car is hot, and under load.