inocnt1

Had an '04 and dyno'd it at 422.
Replaced that car with an '05 and that dyno'd at 360.
Should there be that much of a disparity in our cars?
Or did the shop not know to put it in dyno mode?
I wasn't there when it was done. Two different machines and I couldn't tell you what they are.
Comments would be appreciated.

lane_change

The machine will make a huge difference, as will the atmosphere you were in both times.

If you dyno'd your 04 in cold weather on a dynojet, you will get a high reading....especially in comparison to a hot day on a dyno dynamics. aka The Heartbreaker

inocnt1

Interesting. Thanks.
I wonder which is more accurate or true?
One results shows that info the other doesn't. I'll see if they still have it stored and recorded that part. They were both done during similar weather conditions, a week ago and early April last year. And similar elevation. Don't know about humidity and I'll see what machines.

jangy

Dyno runs are very relative, depending on how the run is setup. Said that, 420 to the floor is about the mean and shouldn't vary more than 20 plus minus. Under 400 to the floor is not good. I don't think it is your car but the run sounds bad.

lane_change

The dyno dynamics is considered one of the most accurate dynometers, where as the Dynojet is the most popular and is considered the number that everyone uses when they reference their rwhp...even people who dyno on other machines, they generally do a conversion factor to tell people what their car would have made on a dynojet.

For tuning, you will do better with a loaded dyno, dynapack, dyno dynamics, etc...vs. a dynojet which offers little resistance and almost zero repeatability.

Marcus Frost

inocnt1,

Find out what kind of dyno's they were on and we can go from there. That is a big variable. The other is a bad water pump. If you just picked up the '05, water pump could be an issue. No E55 should dyno 360rwhp - even on the dyno dynamics. My previous '03 E55 did 36xrwhp on a dyno dynamics when it had a bad water pump.

E55s will vary from car to car... I've seen from 380rwhp to 400rwhp for healthy cars on a dyno dynamics.

-m

inocnt1

Ok.
One must be a Dynojet cuz that's on the page three times. It also has the temp, etc. And is the lower of the two. Done on the new car.
The other one only shows "dynorun.002" as I guess the runfile.

Based on the comment above, a cold day on a dynojet should have produced a number substantially greater than 360.

So my baseline dyno is f'ed up. Oh well.

Marcus Frost

inocnt1,

Start with the water pump... on the dyno with limited airflow a bad pump will severely impact numbers. Order yourself up a CM30 or whatever weapon of choice and take that variable out of the equation.

-m

inocnt1

found out both shops were using dynojet.
also found out that the low results, they didn't put it in dyno mode. they just turned off the traction control.
would've been nice to have a baseline to see what i was starting from. oh well. glad to know they screwed it up rather than it being the car.
thanks for all the comments guys.

lane_change

Dyno mode doesn't make more power, so you should still not have seen a decrease in hp to that extent. TC off, Dyno mode, etc...when you are in 3rd or 4th gear (if you are chipped), you will not be spinning the tires at those speeds, so your peak hp should be the same. Your tourque could be off if you spun at first, since peak torque in our cars is so low in the rpm band, but dyno mode should not have made any difference in your power output. Look into your pump.

inocnt1

If the pump was off, would the car feel any different on the road? I didn't notice anything different during driving.
I've already swapped all the parts from the wrecked '04 to the new one. Part of that was a pump, so the pump has been taken care of (if that was the problem).
Still have to do an after-mods dyno.

If it's not in dyno mode, doesn't it stop revving at 4000rpm? Similar to revving it in park/neutral? I thought that would make a difference. And going to dyno mode, it lets it rev like it was actually driving?

enzom

I don't think that's right. I think the car is always going to pull timing on a dyno if you are not in dyno mode. Something about the rears spinning without the fronts spinning. That's why the car has dyno-mode to begin with.

lane_change

If so, that would make sense...I know at the track, I notice zero difference in dyno mode or not, but I never thought about the front tires. Sorry for the mis-information if I am wrong. I know when you are spinning it causes a difference by decreasing the timing and applying some brake.

I know when I dyno'd mine, we had to do it in 3rd because my stock ECU would not mph enough for a 4th gear pull.

I Like Soup

I can tell you from personal experience I ran my car stock on a Mustang dyno and it ran a 409hp (if I remember correctly) and then I took it out of dyno mode and it ran a 388hp or so. Whether people like to believe it or not, dyno mode makes a difference...again, from my own personal experience. I'll go dig up my old post...

jangy

HP is calculated based on TQ. I've seen lots of E55s have low HP peak figures from a bad dyno "launch".

Dyno mode makes a difference on the dyno and on the track. To say otherwise is like saying Drag radials don't make a difference. Some don't notice the difference, but that is not the same as there not being a difference.

lane_change

Yes, I understand that if you are spinning, and if the computer begins to pull timing, apply the brakes, etc...but as soon as you are not spinning, does being in dyno mode offer anything extra? Talking about the track here again, if the front tire thing is correct for the dyno, then I will conceed that point. Since you rarely see cars spin on the dyno, that is where I based my assumptions from.

But for the track, just like you mentioned, drag radials not making a difference. Again, true for the holeshot, but otherwise, a drag radial will generally offer a disadvantage if you are concerned about trap speeds and such due to the lower air pressure and larer surface area and friction. So are you saying that once you leave the line (done spinning) that being in dyno mode basically makes more hp than not being in dyno mode?