Finally Got Dyno numbers on my combo if anyones interested.

go-stang5.0

New Member
Jan 27, 2003
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Glenview,Il
Hey guys those of you who remember me I've been busy and lazy and havent been on here for a while. However when I go back to school I should be on mor often. In the mean time.....

I ran on a pod dyno this morning (a Dynapack). If anyones heard of one...they seem to be a lot better than dynojet roller dynos in that they remove the wheel/tire interface. The pods attach to the hubs of the drive wheels and use a hydraulic brake system to measure hp. There relatively new and cost about 2x as much as a dynojet to buy (which makes me assume there better :) ). You can do a google search on them for more info. Anyways I made:

409hp @ 5400 rpms SAE corrected
1549 ft-lb @ 4300 rpm (Note: this is actual wheel torque due to my 3.55 rear end, engine torque after drivetrain losses would be 1549/3.55 = 436 ft-lbs which is the number everyone is used to to seeing)

All this was while running an A/F between 13.76 and about 2000 rpms dropping slowly to 12.45 at 5800 rpms. At peak hp the A/F was 12.68. This is all while running stock timing and cpu and premium pump gas on a 10.8 to 1 compression ratio.

The only problem I have is that my sae correction was very high about 1.23 throught the rev range. This was because it was about 100 deg. in the shop and the temp probe on the top of my air filter (just sitting on top with my hood open) was reading 140 deg. due to the heat from my engine (I dont run a filter in the fenderwell). This temp was also later verified with a laser pyrometer. They dyno operater told me the sae correction factor was so high because of the inlet air temps and that the correction although high was correct in my case. But in any case I'm happy even if the numbers are 10-20 hp less in reality although I am told this is unlikely as the correction factor should be accurate in my case.

Also to get flywheel hp/tq he put in a 1.16 correction factor (meaning 16% drivetrain losses to calculate flywheel power). My car has a T-5 and the rear end has 144k miles on it (besides the ring and pinion which are newer) but I dont think drivetrain losses are that much. Anyways with those estimated losses the motor makes an estimated 474hp and 506 tq.

Sorry for the really long post but chime in and tell me what you guyz think. I'll try and have my graphs and tabulated data posted up sometime tonight when my neighbor gets home from work.
 
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Go to the TRACK, thats the REAL dyno. Fwiw, on any normal dyno you aren't making over 400hp at that low of an rpm with that combo. Nice "numbers" I guess though.

Let us know when you get real numbers, like at the track :D
 
DSS 331-7qt pan, windage tray, stud girdle, steel crank, forged I beams (light weight), forged pistons, AFR 185's stud mounts box stock w/ spring upgrade, edelbrock performer rpm II intake, comp cams extreme energy 218/224 @.050" and .544" lift on both lobes, 70 mm TB, 73mm C&L MAF, aluminum Romac Balancer, aluminum flywheel, and a drilled/lightened SPEC pressure plate. I don't see too many people making this much hp with similar motors so I dunno, assuming the dyno and corrections are correct....my best guess would be that I have a lot less spinning mass which I made sure to mention above. Anyone have any other ideas or feel that my SAE correction seems wrong...let me know. Cuz to me my numbers seem a bit high.
 
You tested your car on a different kind of dyno, so your comparison is a wash. Like I said, get some track times as thats the REAL dyno. You definatly won't hit near 400rwhp on a normal chassis dyno with that tiny ass cam. I too have light weight rods, balancer, flywheel, driveshaft and even my mcleod clutch disk is lighter than the king cobra. I highly doubt that'll show up on a chassis dyno, those kinda mods (IMO) will show up at the track.

Go to the track! I can see you running around 115 ish mph on average which is no way near 409rwhp.

Go to the track :D

You combo has lots of potential, if you can swap that cam for a GOOD custom. Whats your exhaust set up?
 
I agree the numbers seem high. I just wanted an opinion as to why this may be. And I went to the track last week...It was 85 deg. outside and my car ran a best of 13.4 at @109 which is pretty much the same as the time I have posted on this site in the user times. This was on 255/40/17's running a 2.3 something 60 ft all night.

As to the dynapack dyno do a google search like I mentioned before...you will see pics of it and a bunch of info. It is several box like (pods) which attach to the hub of the axel (with your wheels and tires removed). Basically when you floor it you spin your wheel hub which is rigidly mounted to this pod. The pod itself has a pump and orfices and a bunch of oil in it. Based on how the oil flows and the oil pressure generated by the spinning car hub in this "pod" it calculates hp. It can also create restricitons in the orfices acting as a load on your car to do load tests, etc. Check out their home page http://www.dynapackusa.com/

Does anyone think my correction factor is too high? If I remove it all together I end up with 334 wheel hp, which sounds reasonable. However on a day like this 90+ deg. and a 140 deg. inlet air temp there has to be some kind of correction factor added. With a 1.09 correction factor it comes to 364 wheel hp...that sounds more resonable to me. How about you guyz.
 
i dont wanna spend money on slicks...I'm saving for a new set of wheels, street/autocross tires, a new set of all seasons for my current wheels, brake pads, and a chip from JMS so I dont have to deal with bucking and surging and all that crap I have been dealing with for the last 2 yrs. If I can find someone who will lend me slicks I will go back to the track on borrowed ones but if i buy them I will prolly use them once and try to sell them because I have no use for them. I'd rather not waste that kind of money...i think numbles may let me borrow his slicks..I'll ask. But yea my current times are not very useful because I was spinning in first and second so its a pretty crappy way to compare how much hp I may have.
 
we have basically the same combo except the heads and intake, little difference in the cam as well. Those numbers are almost 100pts higher in both fields compared to mine which dynoed at 316rwhp and 354 rwtq on a Dynojet.
 
Yea as mentioned before I do agree the numbers seem too high. However I looked at the dyno sheets again and without the sae corrections (409/1.23 = 332) it made 332 wheel hp which sounds pretty reasonable. Also, they said it was like 100 deg. in the shop but the high today was only 86 deg. Anyways where I'm going with this that the dyno numbers arent so off but its the SAE corrected hp that is wrong. In my mind a car does not make a (seat of the pants) noticable increase in hp when the ambient air temp changes from 86 deg. to 68 deg. (which is the temp that SAE standardises to). Also, when my car got hotter (the later of the three runs) it actually made a bit more hp than the earlier runs. Leading me to believe that for my motor the heat today made even less of a difference. So my opinion is that my corrected wheel hp should be somewhere between 332 and 350 and not the 409 that the dyno cpu calculated for me. Let me know what you guyz thik about my theory. And finally do you guyz think that a 16% drivetrain loss is reasonable...it seems a bit high to me. Let me know on that too.

The one thing that does not make sense is that my air filter temp was 140 deg. This is obviously where the big SAE correction came from. The temp was verified twice and my filter was appaerently that hot but I doubt the air coming into the filter was that hot. Some one chime in on this too.

Feel free to shoot down my theories...I wanna hear what you dyno experienced guyz have to say. I just want to try and get this straightened out so I can get some more reliable numbers for a base line before I call JMS and get a chip and get a after run.
 
I'll have to look into that zenboy. Free up my schedule hopefully. Yea everyone sez I need a bigger cam but I barely passed emissions with this one so this one is gonna stay. I have my valvetrain setup for up to a .600" lift (afr spring upgrade) and the heads and intake have plenty of flow left in them but I need to pass emissions and so the cam cant get bigger right now. However if I find a way to get out of emissions then yea I will swap to a nice big custom one form Ed. But for now this is how its going to be.