Rolling roads & true E34 power output - The Unofficial BMW M5 Messageboard (m5board.com)

Bryn · 11th September 2003, 23:23

Ok I know the phrases rolling road and true power output are somewhat of a contradiction, but...

I've been reading recently that E36 M3 Evo's regularly produce only 280bhp on the rollers, instead of the quoted 320bhp.

I'm quite keen to get my M5 on the rollers before I go ahead with the Schrick cams, just to get a good idea of what the rebuid/cams and remap really do for the output.

I remember someone on here has a graph from AMD who remapped their car... anyone owning up to that? I'd be interested to see what the output was, and if it is close to the quoted 340bhp, or if the E34's are down like the E36's.
Am I correct in thinking that the S38 engines were handbuilt, where as the S52(?) weren't?

Does anyone else have any measured figures for their E34?

I'm slightly apprehensive about subjecting my car to rolling road treatment with a suspect head gasket. I will seek professional advice first, but I've got a good feeling they'll all say NO WAY! So I may never know what the real gains were, which is a shame

Cheers,
Bryn.

Hollis · 12th September 2003, 00:51

Are these EVO's reading back their RWHP, or the corrected crank HP? Those numbers sound like the RWHP output, which when corrected would come back at around 320bhp.

I remember seeing a while back where a guy had put his S38B36US car on the dyno and pulled out 285rwhp, which would put his engine about 320bhp. Again, pretty good. I imagine if you had a B38 it should do something more along the lines of 295rwhp, more or less. Five or six speed doesn't matter.

Update: I found a dyno run made by Rob Levinson, which can be found here. Seems like fairly regular results to me.

GDA · 12th September 2003, 04:56

Bryn

Before subjecting my 95 to the DynoJet, I searched all over for posts on dyno figures for 3.6 and 3.8s both stock and with mods (chips, cams etc). Here is the list with HP and then Trq

3.6 - 281,242 (Dinan chip), 273, 239 (JC chip), 271, 248 (new motor just broken in), 268,245 (Dinan chip @ 100k miles)

3.8 - 275,242 (JC chip and very high altitude), 318, 282 (Rob's car with JC chip & cams), 286, 248 (stock)

My 3.8 with GPower exhaust put down 286 and 257 lb ft. Here is my dyno chart along with another guys 3.8 dyno'd that same Sat morning.

http://members.roadfly.com/gda/R3Comp.gif

Bryn · 12th September 2003, 09:38

Thanks guys

The E36 figures are definitely at the wheels - the info is from a well known BMW specialist in the UK. I must admit I was surprised to hear that too.

Just looked at Rob Levinson's site, and he seems to quote his car at 380bhp (with just a chip!), but the dyno clearly shows 318bhp at the wheels... can anyone explain?

Cheers,
Bryn.

Mmm-Five · 12th September 2003, 11:47

I thought the transmission loss, etc. was 15-20% so a 320bhp flywheel would be 260-270rwhp.

I guess the European 3.8 M5 (340bhp) should be something like 270-280rwhp and the 3.6 M5 (315bhp) should be around the same as an M3?

I'm just posting the AMD dynoplot that I found in my gallery.

Comparing figures is a bit pointless unless they are all done at the same time at the same place by the same operator. Use them as a guide to what percentage increase you gain from a mod but not as a guide to how much actual bhp/torque!

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