Dyno results, couple questions

[murphster]

Made the switch to XFI and had it tuned on the dyno (thanks Cal). There was a problem with the rpm pickup so the dyno operator switched over to the roller pickup. The rpm readings were a few hundred rpm low. I have the XFI logs and I know what the actual rpms were from the these logs.

I know that the dyno measures torque and uses the rpm to calcualte HP with the formula:
HP=Torque x RPM/5252

I have the dyno logs and corrected the rpms to what was recorded on the XFI logs. With the new rpm I recalculated the HP with the above formula. Anyone see anything wrong with this? Get more HP since the rpm was actually higher for each torque reading. But more importantly, the shape looks more reasonable and I can use it for looking at my power curve.

I'm surprised my power starts falling off so soon, thought it would have pulled to a lot higher rpm. I have a 224/224 roller cam, T&D 1.55 roller rockers, GN1 heads. Running a PTC converter.

The good news is that it made quite a bit of power on 93 and alky at 24lbs boost, 18-19 degree timing. The pics are the original dyno, a dyno with the rpm corrected and new HP calculated, and the XFI log.

 

[bison]

Pm me the cam/cam timing info as well as backpressure if you logged it. Hp/road speed will help determine if you're going to be where you should be. Flash stall is very important

 

[murphster]

 

[Pronto]

Sounds like a jet taking off!

 

[bison]

Sounds like a jet taking off!

Its definitely got some nut.

 

[Turbo6inKY]

Without an RPM pickup from the crank, your dyno charts are worthless. Everything on them is wrong. Your XFI logs are fine and you should definitely make adjustments based on those readings, but do not make changes based on your dyno readings, they're wrong.

You should get your money back from the shop or get them to let you bring it back when they've fixed the crank pickup (or use the inductive pickup on a spark plug wire). The slip in the converter screws up the math badly.

 

[20psiofevil]

Looks and sounds good from here
Couple questions if you dont mind sharing, what turbo, what size nozzle(s), what target af? I'm running a very similar cam btw.

 

[murphster]

Without an RPM pickup from the crank, your dyno charts are worthless. Everything on them is wrong. Your XFI logs are fine and you should definitely make adjustments based on those readings, but do not make changes based on your dyno readings, they're wrong.

After reading up some more, looks like I did it backwards. The HP is correct but the torque is calculated from the HP using the rpm. From what I understand, with the Dynocom dyno its a known issue that the rpms may be shifted using the roller for rpm pickup if the starting rpm is off. Therefore the torque calculations would be off. Substituting the rpms from the XFI log should give the correct torque calculations. This makes better sense since the new calculated HP numbers seem high.

On the chassis dyno the HP is calculated independent of engine rpm so it doesn't affect the readings. Only comes in to display the rpm vs power curve and to calculate torque. Since I know my rpms and can sync them up reasonably well to my XFI log, the graph should be pretty close. I have the dyno log dumped to a file, thats why I can edit and scale it. I knew the original charts were worthless.

 

[murphster]

Looks and sounds good from here
Couple questions if you dont mind sharing, what turbo, what size nozzle(s), what target af? I'm running a very similar cam btw.

Precision billet 71HPQ. Running an M10 and M15. Mid 10s A/F. From past experience my car made similar power from 10.3-10.8 A/F so I usually ran it on the richer side to be safe.

 

[murphster]

Here's the new dyno with the torque calculated from the HP at the new rpms.

 

[SHADOWII]

That's very impressive, Congradulations!

 

[Amelio]

Damn!

congrats thats a bad ass ride you got