Page 1 of 1

Interesting Dyno Graph - 745i vs m30b35

Posted: Jun 28, 2007 12:04 PM
by T_C_D
I finally have enough data to give a good comparison of a stock 745i vs our kit.

This line the graph shows the engines making the same rpm and the same boost level. It's not totally scientific but it's the best I have to date.

Both runs on same dyno but different days.

745i - good condition engine with auto tranny - 55F ambient
m30b35 - 100 miles on fresh motor with SEM - 89F ambient

Image

I am not making any claims just sharing some data. It obviously isn't a perfectly fair comparison so take it at face value. 745i cam should make more torq than the b35 cam at this rpm.

Posted: Jun 28, 2007 12:52 PM
by turbodan
Wow. That 745 was really lacking. Maybe the auto tranny was sapping it up. I'm assuming the 535 was manual.

Posted: Jun 28, 2007 1:36 PM
by russc
Which line is what car?

RussC

Posted: Jun 28, 2007 1:49 PM
by T_C_D
russc wrote:Which line is what car?

RussC
Top line is TCD car.

Posted: Jun 28, 2007 2:24 PM
by Boru
russc wrote:Which line is what car?

RussC
Did you REALLY need to ask? ;)

Posted: Jun 28, 2007 2:26 PM
by Nebraska_e28
Very impressive! Was the m30b35 in a manual or auto?

Also, I'm still fairly new at reading a dyno chart. When testing with a 5spd gearbox, should the chart show a bit more of a hp/tq drop between shifts than an auto or is there a way to minimize this?

Posted: Jun 28, 2007 2:40 PM
by T_C_D
Nebraska_e28 wrote:Very impressive! Was the m30b35 in a manual or auto?

Also, I'm still fairly new at reading a dyno chart. When testing with a 5spd gearbox, should the chart show a bit more of a hp/tq drop between shifts than an auto or is there a way to minimize this?
Dyno pulls are always done in a single gear and usually in the gear with a 1:1 ratio.

In this case the e34 was in 4th gear (manual tranny) and the 745i was in 3rd gear (auto).

5% is the generally accepted additional loss for an auto tranny.

Todd

Posted: Jun 28, 2007 3:20 PM
by turbodan
Does the 745 have a lockup torque converter? I can't imagine only 5% through an open torque convertor, with a hydraulic pump and planetary gears. It really seems like the 745 should make more power than it did while it was making so much more boost unless the tune sucked.

It spiked to 4.5 psi more and still didn't quite match the output. That can't be right.

Posted: Jun 28, 2007 3:27 PM
by T_C_D
turbodan wrote:Does the 745 have a lockup torque converter? I can't imagine only 5% through an open torque convertor, with a hydraulic pump and planetary gears. It really seems like the 745 should make more power than it did while it was making so much more boost unless the tune sucked.

It spiked to 4.5 psi more and still didn't quite match the output. That can't be right.
It's a lock up converter. Consider that the 745i has a less efficient turbo, intercooler and exhaust system and it all adds up.

Tune is fine on the 745i.

Posted: Jun 28, 2007 3:48 PM
by vance
Dan, k27 is very inefficient especially compared to the turbos Todd's kits use. Plus dual 60mm pipes for an exhaust don't help much either. It made a big difference on my car when I put my custom dual 21/2" set-up on. Todd, do you have a picture showing the difference between your turbo and the k27?

Vance

Posted: Jun 28, 2007 3:52 PM
by T_C_D
vance wrote: Todd, do you have a picture showing the difference between your turbo and the k27?

Vance
Image

That is a picture of the stock k27 and the one with the 60 trim wheel. I used that same 60 trim wheel on the e34 dynoed above.

Todd