Bokx_350

Hey guys, So I decided I'm going to dyno my C350. I got an appointment for tomorrow at 1. This is the place whee I'm going to do it:
DSG - DENT Sport Garage - Self Built. A sport garage in Norwood, MA. USA
Apperently they have a Dyno Dynamics dyno (not that I know anything about dynos). So my question is, what whp should I expect from my automatic c350?? What would be a good transmission loss estimate to convert the number I get to crank hp??
Thanks

2tonOfun

Be sure to put it in "dyno mode" (see threads here on how to) and I bet you see about 240ish to the wheels.

Looking forward to your results.

Bokx_350

Yep, already saw the youtube video on this. The tunner at the dyno shop told me that an auto tranny lost could be as much as 25% . In that case it would be more like 205 whp (not cool).

ctgilles

15% loss is my guess. So about 230-235whp.

Is there a dyno mode??? How kewl!

Krytech

Awesome!

Do you mind if I ask what they are charging you? I've found a couple places around here for $75-100 for three pulls but they are dynojet dyno's and I've been told they are one of the least expensive/accurate dynos on the market?

Bokx_350

Their flat rate is $100 for 3 pulls.

palladiumw204

15% loss is for a manual transmission...20-25% is typical for automatics

Bokx_350

Any specific numbers for our cars?

FrankW

18% loss on MB automatic is pretty much the norm. some where between 220-230rwhp depending on the dyno.

if you all really want to know what the car puts down without the variance of what wheels/tires you are running find a shop with dynapack. It'll be a more accurate 16-17% loss without factor in the wheels.

2tonOfun

That's what I would guess, once the tranny reaches a 1 to 1 ratio (not sure what gear that is on the MB tranny).

FrankW

3rd gear on the 5spd

should be 3rd or 4th on the 7spd. probably the 3rd since the 6th and 7th are just overdrive.

BerBer63

5th gear is closest to 1:1 and 18% loss is the standard.

Dynos are at their best when measuring gains/differences from baseline, but it will do.

FrankW

the 5th gear on the 7spd is closest to 1:1? wtf... I always thought the 1:1 ratio is used in the middle in most cases. edit: searched around and you are right. hmm....

jagass

Some said that the place is good...I hope it's true...

C43AMG

The car is rated at 268 at the crank.....how can you expect to see "240ish" ? I'll say 205.....211 tops.

Bokx_350

I agree that is over optimistic. At 18% lost, which appears to be a good estimate, I should get around 220 (268 x 0.82).

Krytech

240 would certainly be too high for a stock engine, but with your tune you might be close to 235-240 to the wheels if the MKB #'s are close?

AMS Performance

18% for MB Autos on Dynojet (they read too high).
22% for MB Autos on Dyno Dyanmics (most realistic real world #s).

Bokx_350

OK, I got the results. Again, this whole thing is new to me, and I just found out that HP is not so defined as consumers (me included) think. It really depends on a lot of things, especially the tranny loss and the dyno used.

Anyways, he did 3 pulls at both 4th and 5th gear; the results were very consistent with the 5th gear being 2 whp lower than 4th gear. The Max whp was 228. I was a little disappointed at first, but the tunner was kind of impressed.

He told me that Dyno Dynamics is a very realistic dyno that actually adds force to the wheels, and that on a Dyno Jet my numbers would have been around 10% higher. He said that as a comparasion, a manual E46 M3 is rated at 333hp and they have dynoed it at 270 - 275 whp, and that the difference from a manual to an automatic is always significant. When I asked to estimate how much power I had on the engine out of his experience he said at least 300HP considering the automatic transmision; this is close to what MKB advertises for their tune.

So the only way to know how much more power i'm getting is to get a stock C350 and dyno it on the same shop. I am left with this number wich doesn't really tells me much. I mean, I could be optimistic and say that 228 +10% = 251 on a Dyno Jet /tranny loss of 18% = 306HP. Or I could be more realistic and say that 228 / 22% tranny lost = 292HP (as suggested by AMS Performance). As the worst case scennario I can take the 228 whp / 18% tranny loss = 278HP

At the end of the day there is no definite answer. I'll post the graphs later when I get a chance to scan them.

FrankW

which tune are you running?

Bokx_350

MKB's ECU Tune https://mbworld.org/forums/c-class-w...ming-up-d.html

FrankW

i see. MKB does make good tunes for MB.

Bokx_350

The tunner told me that the fule mixture was very lean at full throttle. He suggested that I compare this number to what MKB is supposed to deliver, but I'm not going to bother since I'm satisfied with the results anyways.

BerBer63

That's why dynos are at their best when testing differences...otherwise their are to many variables to ever know - 4th vs 5th, Temperature, Octane rating, Fan Setup, 18s vs 19s, +/- the variability of the dyno itself,etc. etc.

Congrats now you have a baseline for you're next mod

FrankW

your AFR went from near 15 to dipping 13 at full throttle. I would be scared a little. only if you have the stock AFR to compare. wonder if that AFR is on the edge. I rather have them run a little richer and sacrefice a little power.

that's a board torque band tho