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I had my car dyno tested today - the results were surprising!

The peak hp was 176 HP, allowing for 18% driveline loss, this means 208 HP at the crank:





Once the Glenwood 24v engine is installed, I'll head back for a direct comparison. I hope its as good as they claim it will be - the 3 liter 12 valve is clearly a tough act to follow

Here is a small video clip.

Here is some high quality audio (MP3) taken of my GTV6 on the dyno ...
Run through the gears
Throttle snaps
Special thanks to JasonS for these clips

Cheers,

Mike,

176 wbhp on a Mustang Dyno is good. Was this with a stock L-Jet?

Fantastic Mike,
Hopefully the 24v unit should produce more. Mine hasn't been dyno'd yet. Have to sort out some issues with idle rpm. Couldn't get it to go down from 1330 before using the LM-1 Innovate Motorsport wide band meter. Managed to get it to about 1000 rpm but reading for AF is close to 15. Mike, are you also using the gotech pro?
Zamani, I take it autronic is easier to tune? Did you have any problems fine tuning it. Maybe Motec might be the go???

Those are great results. I assume you are still running S cams, ported heads, headers and Gotech.

I think Mike was using MS at one point and swapped back to L-Jet.

The setup is Sperry Stage II heads, S cams, CSC manifolds, Stebro middle exhaust and a stock rear exhaust with L-Jet (lightly modified ecu) and Greg's intake kit.
It also has over 200k miles on it and 7 seasons of track use
Gotta love Alfa engineering!

Brian - yes, the 24v came supplied with a GoTech Pro.

far out . so 176hp with ljet. thats quite impressive mickey so even though u have stage ii heads and cams and such, having the bottleneck of the airflow meter in the intake before these modifications the engine is still able to be supplied with enough air to make that sort of power. i am impressed and cant wait to see quarter mile footage soon..mmm mouth watering hubba hubba, lol nah well done and cheers to you my friend!!

Ok, I see the loss factor discussion coming up again after Michael's dyno plot. Since I must make a decision about what you guys will read in the V6 book, I will ask for a general opinion on it. Do you want the book plots to only show wheelpower? If you want engine power, what do you think is a reasonable loss for transaxles? Most dyno shops in my area agree around 8-9%. One exception is a dynapack rig who used 18.5%. I am attaching the two curves from my previous engine (removed 2 months ago from the car)taken months ago within 2-3 days from each other. One (the low power one) comes from a respected local car-mag dyno using 8% for our cars and was taken after ECU mapping. The other is from the Dynapack, where they take the wheels off and attach the dynos to the hubs. This used 18.5% loss and shows power before and after performing Motronic ECU mapping. 205hp is way less than 235hp (engine) but wheelpower is respectively 190 and 199 for the two, within 5% from each other. I like to believe the lesser numbers.
In case you ask, the engine is a 3liter with Motronic (S) cams, mild porting, std runners, 11:1CR, CSC headers, 63mm SS exhaust with 2 mufflers, no cat and a...sunroof, hahah!
Jim K.

Jim,

Just put wheel power. Let readers use their own loss factor .

IMHO, 18.5% is very high....

JimGreek wrote:Since I must make a decision about what you guys will read in the V6 book, I will ask for a general opinion on it. Do you want the book plots to only show wheelpower? If you want engine power, what do you think is a reasonable loss for transaxles?

Good question about losses, but unfortunately there's no universal answer on it.

Real losses aren't only prosentage part of the engine power. There are also some losses which are dependent on driving speed, tyre type/size and axle weight, but not much to do with the amount of power transferred via driveline. That means the total loss prosentage value may vary a lot and the number is typically lower with high power engines.

The prosentage loss of engine power is also there and it can also vary depending what kind of tyres and dyno is used. The transmission teeth contact loss is easiest and least changing part, but the tyre-roller contact does a big differences. In worst cases there may be even 10% slipping on the contact and it still feels like tyre does well.. 10% slip means also 10% power loss in only this part of the whole loss chain..

Those wheelpower values you got are really very near to each other, but there's also some luck on the game. Anyway, the wheel power is still the best number to compare.

If having access to engine dyno, it would be good idea to do a comparison between it and the chassis dyno you are using. Later using same tyres and similar mounting of the car on the same bench will quarantee reasonable accuracy for absolute power values. Relative values will usually work, if nothing else changes..

As people use to want to hear about engine powers, if claiming something there should be heavy note that the values are based on certain approximations. After all, maybe you should give some values to satisfy the readers.

Yep, tyre to roller losses vary heaps depending on everything like size, pressure and compound.
Around here, the standard seems to be anything from 18-30% assumed total losses. This has always seemed high to me and I tend to go looking for the 50kW heat exchanger it is being lost through .
Best use of a dyno is a tuning tool and then in the same conditions and preferably back to back.
Another good one is to put a stock, fairly new car on first for a comparison of rwhp to the known factory output. My wife's turbo Subaru is going on the rollers this weekend for just that reason. Though maybe I'll wind on a couple of extra pounds of boost and do a second run just to see - I can't help myself

As I once investigated gas and spark plug effects on the dyno I asked him to do multiple runs at one setting to check repeatability.

The dyno was Bosch or Maha, can't remember for sure.

The results was that engine power was within 0.5%.
HOWEVER, wheel power varied a lot (3-5 % I recall). This is because tire temperature has a big impact as also gearbox oil most likely. What probably has a huge impact too is how hard you strap the car down on the rollers. All compression on the tire sidewall is (unnatural) loss.

So, my anser is:
Use a decent dyno which measures both.

Rototest...

I remember talking to Joe Beninca about this. He seems to agree around 15%. Why I tend to believe what he says? Because he has both chassis and engine dyno.

Ok, stupid question time - Are the losses really a constant percentage.
If you had 150hp atw and calculated (@18%) 177hp at the engine, that's 27hp in driveline and system losses.
Now, for arguments sake, you supercharge/turbocharge and get 300hp atw calculating to 354hp at engine meaning 54hp lost in the system. Once again I'm looking for a big heat exchanger in the driveline somewhere - I find it difficult to lose that kind of hp somewhere. I could be way off track though.