Black LS1 T/A

How accurate is HP and TQ in Autotap?

It always read low, in my experience.
Is it trying to calculate brake horsepower and torque?

Thanks!

Black LS1 T/A

I have the stock MAF... I heard that made it pretty accurate. Kenny at GWP says in his experience, the dyno is about 20% more than the autotap calculation. But, I don't know how that is affected by the different altitude out in Colorado.

Spydum

All depends on the car. I dyno'd my car while logging ENGTQ and TRANSTQ with EFI Live, and found its accurate, just about 20 higher than actual RWTQ delivered. So If you just keep in mind its -20 (I think on EFI you can set it to subtract 20 from the value too), it's great for seeing power gains. Then ofcourse, HP is just a formula derived from TQ/RPM ( (RPM*TQ)/5252 I believe..)

SJH

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Kenny at GWP says in his experience, the dyno is about 20% more than the autotap calculation. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The dyno should read about 20% less, just as Spydum has observed.

Team ZR-1

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Spydum:
<strong>All depends on the car. and found its accurate, just about 20 higher than actual RWTQ delivered. So If you just keep in mind its -20 (I think on EFI you can set it to subtract 20 from the value too), it's great for seeing power gains. Then ofcourse, HP is just a formula derived from TQ/RPM ( (RPM*TQ)/5252 I believe..)</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The PCM is calculating the delivered torque at the engine so depending on the drivetrain and trannie type you would subtract that loss to what the PCM is reporting.
Drivetrain loss would be different on an F-body then a C5 with a drivetube and transaxle so a 20% loss would be too much, more like 12% as a torque loss.

<small>[ November 25, 2002, 01:13 PM: Message edited by: Team ZR-1 ]</small>

SnakeStomper

iTrader: (8)

Can you also calculate HP and TQ with EFILive? If so, how can I do it? I'm just beginning to learn this tool. Thanks for the feedback and sorry for the dumb question.

Black LS1 T/A

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SJH:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Kenny at GWP says in his experience, the dyno is about 20% more than the autotap calculation. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The dyno should read about 20% less, just as Spydum has observed.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Either I misunderstood what he said or maybe he was talking about what the dyno reports at their altitude (5800').

Black LS1 T/A

I recall that my calculated horsepower was always lower than my dyno. But this was a version or two ago when I tried it, I think.

I had heard it was a useless parameter to measure (proabably was, with the earlier versions of AUTOTAP), so I never logged it and rarely inserted it into my monitoring, based on my experience and what I'd read/heard. Before the Supercharger, I dynoed 297 RWHP, and it seems like Autotap always said it was around 240 or so... I wish I'd bothered to log it now, to be sure. <img border="0" alt="[whiner]" title="" src="graemlins/gr_cry.gif" />

This is a good discussion. I'm glad I brought it up. At least I have seen it is useful for "relative" tuning... seeing if what has been done makes a change for a particular vehicle.

Team ZR-1

The problem is that autotap scanners have always had a delivered torque bug, the PCM does output a valid value. The car uses that value for other functions, esp with a Corvette that has active handling, traction control etc.

If you see negative DelTq values, it would be valid if you had lifted off the gas pedal OR torque management kicked in.
Autotap screws up and outputs math bugs so you end up seeing invalid max Deltq values.

The Ease scanner outputs correct values thus it is a real world dyno you can use to calculate HP and rear wheel values for HP and Tq.

Black LS1 T/A

OK... back in August of last year, just before I put the supercharger on, when I was making 297 RWHP and 345 RWTQ (I had a SY3500 stall converter), they must have just tried implementing the power/tq calcs... TQ was about 60 and HP was 0. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

I tried it again in December of that year with a different version of Autotap. By that time, I had the Procharger and was making 486.3 RWHP and 487.0 RWTQ. Autotap said I was making 74 HP and 304 TQ, so I didn't bother with that anymore, that I recall... at least I don't have any logs of any.

Kenny told me it was better, now, and to monitor it. TeamZR1 also told me I should include them in my monitoring. So I tried it.

Autotap calculates highest power of 622 HP @ 6300 RPMs and 540 TQ @ 3500 RPMs. I am only using 3 or 4 PSI of boost, peaking at 5 PSI until I get a handle on my fuel requirements. I haven't been able to get out of town for runs thru 3rd gear yet and the dyno here is broken right now, so my data is limited, for now.

Oh... the data can be ignored at spots going into and coming out of gear/going off the accelerator. Lools like that induces a spike in the value.