Dynoed my 2.4T this morning

RallyJon · 10-15-2003, 07:21 AM

The results were a bit confusing. The wheel HP numbers aren't bad, but the torque was lower than I expected. Curiously, the motor pulled right up to the rev limiter and made max power right there. It was suggested that an S rotor would give a few hundred more revs and a few more HP. I guess the Webers are happiest at the higher revs.

Still, seems like an oddly shaped power curve for T cams...

I don't have a printout of the lambda, but it was lean at low revs, rich in the midrange and leaned out a bit on top.

Tim Walsh · Tim Walsh's Garage

Most interesting.. Do you know if the engine has been rebuilt? It seems like it might have different cams in it. Give an E rotor a try?

btw 121 at the wheels is spot on for a 73T

RallyJon · 10-15-2003, 09:28 AM

I e-mailed the guy who supposedly installed the engine and webers (two owners ago). We'll see if he remembers changing cams. The way I see it, either:

a) it's a slightly modified motor with bigger cams, is tuned like crap, and would make another 10-15HP with a higher redline and some carb tuning, or

b) it is a stock T, Webers just suck and don't run right until higher revs.

For <$25, and E rotor would be a cheap experiment.

tobluforu · tobluforu's Garage

What will an e rotor do?

RallyJon · 10-15-2003, 09:34 AM

Raise the rev limiter to 7100 (vs 6500 for a T or 7300 for an S)

Tim Walsh · Tim Walsh's Garage

toblu,
An E rotor has a rev limit of 7100 RPMs instead of 6500 RPMS that the T has. His torque doesn't fall off at all before it hits that limiter indicating he maybe shortchanging himself on his revs and thus power.

tobluforu · tobluforu's Garage

Ahhh, I see now. The reason I asked is because in my t, e, rs, I put a V.W. rotor in it-no rev limiter. Some say this is bad, but my car looses juice at about 6600, so it's time to shift.
Thanks

arrivederci · 10-15-2003, 01:39 PM

For comparison, here's a dyno of a T cam with 2.2 S P&Cs. Very flat torque curve, just like yours. The difference in power is due to the higher compression. BTW, the dyno runs I've seen on E and S cams didn't have the flat torque curve of the T.

http://members.rennlist.com/jpinkert/pepe%20dyno%20run.jpg

beepbeep · 10-15-2003, 02:17 PM

Hey, what's wrong? That's a torque curve most would kill for!

You don't see much of that nowadays...at least not w/o turbo and electronic boost controller.

That must be one helluva tractable engine.

sammyg2 · 10-15-2003, 02:36 PM

If a torque is flat (as yours is) the horsepower will straight line up to peak (as yours does). Horepower is rpm times torque (oversimplified).
If I were you I'd try to increase the torque without loosing the shape. Compression is the easiest way I know of.

Your curve very closely resembles perfection for the street as far as shape, the only real problem is with the numbers

RallyJon · 10-15-2003, 05:56 PM

Quote:

Compression is the easiest way I know of.

Josh's S-piston T certainly bears that out. I'd love to just move both curves up about 20 on my chart. If I pull it apart enough to change pistons, it's going to gain about .3 liters in addition to some compression.

It would be a very tractable engine if it had that power curve and EFI. With the Webers it coughs, sputters and complains everywhere except full throttle. They were running great all Summer. Now it's 50 out, and they run a bit lean at part throttle.