robevo8

ahh yess i have seen that number before in regards to a WRC set up cant remember the details, but something along the lines of they dont worry about to much after that, they try to keep everything below 5250.... if some one can fill in the rest of that info or correct me.. feel free

bougs

iTrader: (2)

It is alot easier to make torque at a lower rpm. Once everything starts moving you can not make huge torque numbers because dynamic compression drops as rpm increases. If I understand it correctly.

Basically the efficiency of engine lowers as rpms climb. Certain things make the engine more efficient (cams, heads, etc.) but its still losing it.

The combustion chamber cant evacuate the charge > less new fuel/air > less torque > gets worse and worse as rpms climb.

modthispny

but why is this torque curve so smooth, same car.

murlo26

iTrader: (9)

That is a VD Plot. It has smoothing on and is created from data logs. A dyno plot can be smoothed out too but the more you smooth the more data you loose.

Also its a stock turbo plot, they can be tuned pretty smooth.

modthispny

check out my dyno..is it normal for the torque to drop so much?



check sig for mods.

murlo26

iTrader: (9)

On a stock turbo...yes.

Get a 3 port if you don't have one and it will hold it a little more.

RRE knows their ****, you are in good hands with them.

Guru

iTrader: (6)

Actually the stock turbo is only half the equation. Sure it drops due o pressure falling but even an upgraded turbo does somewhat. The key is to upgrade camshafts and improve breathing after peak torque point. I have done some 272s on big turbo and torque holds flat to 8000 rpm all 380 ft lbs of it

murlo26

iTrader: (9)

Like I said...its easy to hold small amounts of torque to redline on a giant turbo.

You just can't do it on a small one.

I hold 400wtq out to 7500rpm...but revving to 9000 on a stock frame, regardless of cams you can't hold that torque out there.

modthispny

so what do you guys recommend i do? im going to get an AEM intake, dp, and catback exhaust and go back in a few months. is there anything they can do to maybe bring the peak torque down a little lower but make it more linear?

murlo26

iTrader: (9)

I recommend you just don't worry about it

It is just inherit in our cars on stock turbos...just enjoy the boost spike while its lasts! Then shift and do it again!

Golden

iTrader: (1)

That is not true. One great example is Mazda RX7 monster turbo engines. Granted they are not a piston engine, but still... There are others too. It just takes a lot of air to make more torque than lower RPM.

cfdfireman1

iTrader: (11)

they look about the same to me here's an example. max torque 4500 down at 7000 about the same as our little 4's. It looks like the big difference is the torque down low.

fugifighter

I can relate to the OP about the torque dropping after about 5500 rpms. I was recently looking at Dyno sheets from people that were tuned on this forum. It seemed that a 3port/ebcs does make the torque drop off less severe and for about $100 doesnt sound like a bad investment. It's all about the area under the curve, keeping the torque higher for a longer time means more to me than just peak numbers.

The quick "fix" for this is to shift earlier so you utilize the peaks of your power curve. My 06 Sti was tuned with very much the same drop off after 6000 rpms and my tuner told me that to really enjoy it I'd probably need to change my shift points.

I hope to get my evo tuned sometime soon when I finally choose a catback and decide whether or not to get an aftermarket fmic/EBCS. The rest of my parts have been collecting dust in my house for over a year now. (UICP, Intake) I will probably get a tune with just a catback and the parts I have already but I still feel the stock x has plenty of power........... for now.

BluEvo210

I remember from engineering school that peak torque occurs at the RPM where the engine has peak volumetric efficiency (most air pumped per stroke). This depends on the ports, the cams, how the air swirls in the cylinders and a few other things. A turbocharger adds another factor, and lag may affect low RPM with boost affecting high RPM.

I've heard of a few engines that made peak torque and peak power at the same RPM, but these were highly specialized freaks like the Ruf "Yellow Bird".

But, Mitsubishi knew the X was going to be the heaviest Evo ever, so they wanted the turbo to spool up at relatively low rpm.

BluEvo210

I also thought I read somewhere that the Evo X reaches peak boost at 5000rpm, and then the boost tapers off until it's down to 14psi at redline. Whoever wrote that was saying the computer was programmed that way.