Dyno - 2004 Base Auto with Injen CAI

[ZubenElGenubi]

I went to SGP Racing yesterday to do a baseline dyno before installing the supercharger. Mark Gust did the run on a Dynapack chassis dynamometer (connects directly to the wheel mounts). Charge was $75 for a warmup run and two full pulls.Here's a shot of the screen just before we started the run. Note the temperature (circled). Yep; it was HOT and only got worse. Not a lot of circulation there unfortunately. Here's Mark between pulls. He was having real problems keeping the heat down after the first pull and noted that it was making it hard to measure the gear ratio properly. Apparently, high temps can affect the performance of the torque converter and change the gear ratio. Just to give you an idea of how hot the engine got, take a look at these numbers from the ScanGauge after the first pull.Yep, 136ºF intake temperature! Of course, the car was not running at the time, even though we had a fan on and the hood up. Water temp got as high as 220ºF at one point. Note the Vibe dash temp showing 104ºF in the background. It usually reads about 3 degrees high, so 101ºF is about right.Well, that said, here is the printout: Yep; 96.3hp @ 6100 rpm; 99.1 ft-lb @ 4328rpmNeedless to say, I was stunned. And sweaty. Note that these are not SAE corrected. Mark showed a display with SAE calcs and the numbers were about 10 points higher for HP and torque.Also note the gear ratio...4.090. I am wondering if this was an effect of the high heat, as Mark mentioned. Gear ratios for the auto tranny are:1st: 4.012nd: 2.213rd: 1.43OD: .98Overall: 2.96As the run was done through third gear, I don't know what the calculated overall ratio should be.. (edit: see followup post below)Anyway, when I go back for tuning, it'll be in the morning!

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[ZubenElGenubi]

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[ZubenElGenubi]

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[ZubenElGenubi]

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[Shadow-Vibe]

Damn this is some sad news. I have to get that engine I got for real cheap built so I can see some real horses.

[northvibe]

The heat should have a pretty big factor in those low numbers too. Im pretty sure BC's numbers were a little higher and he has awd. But all dyno's will show different numbers aswell. zuben thats cool, i cant wait till you get that SC on that puppy and see another dyno!!

[ZubenElGenubi]

Heat is definitely a limiting factor, but hard to say just how much here. It would be ideal to know some formula that relates each degree of temperature change to horsepower, but probably too many factors to know.Here's one thing still buggin' me. The reported gear ratio was 4.09; this would be the overall ratio through 3rd gear. Based on the specs listed in my initial post (culled from previous posts @ genvibe), the overall ratio should calculate to 4.23 (i.e., 1.43 x 2.96). Today, I took the car on some runs in 3rd gear @ 40mph and got an RPM range of 2400-2450 (on the ScanGauge II). That corresponds to a gear ratio of 4.44-4.53.I'm stuck on the math here. What's the relationship between the gear ratio and power output (HP)? Are the proportional or inversely-proportional?

[BlueCrush]

Yeah, it seems that heat may have been a factor on your dyno. I made 107.4whp/101wtq on mine and it was between 85°-90°F at the time I did it. Can't wait to see the after #'s.

[Mavrik]

Wow... yeah I'm going to agree with the others that heat had a factor in the poor readings. Find a cooler day to do those runs for sure. I'm beginning to wonder if my G-Tech is maybe accurate... it showed me 110 whp at the drag strip...

[NascarXprt]

kinda hard to do in Tejas especialy in the Summer times. to wait for a cooler day, we have to wait till some time between Oct. and Feb.

[Mavrik]

yeah I suppose thats very true.

[ZubenElGenubi]

Well, as I was jokingly saying to Mark @ SGP, when I come back for my tuning run, I'll be waiting outside their shop at six in the morning!! The upshot of all this is that, if my numbers after the S/C + EManage go as they should, SGP will look like they performed a miracle on my car!