03 Cobra with a TVS TQ concern with dyno sheet and data log

SVT_Troy

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What is causing my TQ to roll over around 4500rpm versus staying flat like most S/C'd vehicles?

I recently had my car re-tuned after changing over to a return system. I have not had this engine/blower setup on the dyno prior for comparison. The car runs wonderfully, infact if i hadn't decided on putting it on the dyno to do a pre/post E85 pull on the dyno i would have never thought there was an issue.

I think these are all the pertinent details needed to make a assessment but if not ask away. I have built this car myself top to bottom.

Attached below is a copy of the dyno pulls and the data log for these pulls.

  • Tuner: Kevin Dunn aka 04lsleeper
  • 93 Octane
  • Target AFR 11.4 with 18* timing
  • Dyno: Dynojet 224X
  • Aluminator shortblock
  • Fox Lake Ported heads with crower springs, titanium retainers, ferrea SS valves
  • Ford GT cams (degreed at Intake 108° Exhaust 114°)
  • TVS
  • 3.0 upper/stock lower (making just under 16psi)
  • GT500 TB
  • SCT BA2600 MAF
  • JLT high boost intake
  • ARH 1 3/4" headers O/R X-pipe necked down to 2.5 Borla catback

37797843451_9db461dfd5.jpg
93 Octane dyno sheet by Troy, on Flickr
37539743280_9728a44318_b.jpg
Untitled by Troy, on Flickr
 

MG0h3

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I don't see a torque line at all. Zoomed in and I can only make out three lines which are the three pulls.
 

SVT_Troy

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I don't see a torque line at all. Zoomed in and I can only make out three lines which are the three pulls.

Is that better?

37797843451_5a5d8f6656_o.jpg
93 Octane dyno sheet by Troy, on Flickr
 

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MG0h3

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Ya man I still don't think he has the torque curve on the graph. I'd call tomorrow and ask and get a different printout. I feel safe saying there is literally no way that a forced induction car will have torque and HP overlayed like that. Even an NA car doesn't have them like that.
 

SVT_Troy

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Im not sure i understand. The tq curve is on the graph unless im missing something. It just isnt typical which is what im trying to figure out.
 

MG0h3

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ah ok I am seeing it now. Its very faint for some reason.

I've never seen a torque curve on a PD car that looks like that. I just looked at mine from 4yrs ago and its like a cliff going straight up and then just flat. Comes down just a hair after peak torque. I'd assume its something with the settings on the dyno/printout unless having cams has something to do with it, which I doubt.
 

c6zhombre

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I don't see anything wrong with it......the X-axis RPM is as elongated as they can graph it.....go back to the shop and ask them to make the sheet 2000-6500 and the TQ will graphically flatten for sure.

Also, the tune is a safe pump gas tune....your max timing 17.75 isn't until 6200 rpm....it's only like 14 degrees on the hit when the throttle fully opens at around 2000rpm. I'm betting the E85 tune will lay the timing much faster down low versus this 93 tune and you will see the shape change on the graph.
 

Soap

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go back to the shop and ask them to make the sheet 2000-6500 and the TQ will graphically flatten for sure.

What? No it wouldn't. The "curve" is based on value in the Y axis, not the X axis. The min/max values on the Y axis will still put a curve in the torque graph regardless of how wide you stretch the X axis.

--Joe
 

c6zhombre

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What? No it wouldn't. The "curve" is based on value in the Y axis, not the X axis. The min/max values on the Y axis will still put a curve in the torque graph regardless of how wide you stretch the X axis.

--Joe


well, you tell me....which TQ graph "looks flatter"?

COBRATVS-5.jpg


COBRATVS-6.jpg
 

c6zhombre

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If one made the X axis RPM only go from 3500-4500 the TQ would look like a straight line across. No change to the Y axis. Now you can change the increments on the Y axis and change the TQ curve as well.....whether it's stepping up 100 ft lbs, 50ft lbs....or 200 ft lbs. But to say the X axis is no factor at all is wrong.

The fact is, either set of increments can change the shape, even tho the absoulute values at each raw data plot point might be identical
 

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