dyno'd the 2.7i

[ForcedFirebird]

Well borrowed a wbo2 stand alone from a friend to get the fueling dialed in after my guage took a crap. WOW! Is all I can say. The 2.7i seems to like it a little leaner than I'm used to, got the AFR nailed at 12.8 WOT and mid 14's for idle and cruise. Gave it a couple more degrees of advance on the whole map (up from what we already had) and this car scoots now - still conservative compared to the turbo maps in the sticky, though. Can't wait to get back to the dyno and see what the tuning did to gather numbers. While there I will flash the stock tune for one of the pulls to show a back-to-back comparison. :D

Also started on the headers, once they are finished, the car will get yet another tune, then back to back results again, stock tune and my tune.

[clarkson]

My stock M20B25

Hi guys, new here, just came across this thread and it is interesting to see modified M20's (ok using basically a mix and match of stock BMW parts) and what they are doing on a dyno. I just bought a 1988 325i manual coupe, and went through it back to front with a big service incl dist. cap, rotor button, timing belt, waterpump, radiator, all the hoses and the usual service stuff too. Plus a rebuild 3.91 LSD. And then it was down to the local dyno for five runs using premium fuel.
I bought the car after looking for 6 months, it is incredibly original and never been modified in any way. It has 190,000 kms and has had mainly dealer servicing. Attached is the dyno result. The first run produced 138hp ATW, and the second from last run produced the attached 146hp ATW. So from I can gather, you have to be careful not to backwards when modifying these engines. To me, a lot has to do with the compression ratio and pistons. The ETA engine was always originally designed as a high torque economy engine.
The ETA crank can be used, but the best result is with custom pistons. A friend has just done a run in dyno at 5000 rpm producing 205hp ATW, using the ETA crank, 11.1 JE pistons, and a baby Schrick cam, and stock computer and intake.

http://www.r3vlimited.com/board/attachment.php?attachmentid=33118&stc=1&d=1284891195

[nando]

I think the same.
Inflating your numbers with fake made up drivetrain % loss
to Brittish HorsePower is bull shit, and just a big guess.

lol

[StereoInstaller1]

Then I learned they convert to brittish horse power

Uh, no.

BHP is short for Boiler Horse Power, Brake HP or British HP...but British is the same as US.

Check it: http://en.wikipedia.org/wiki/Horsepower

[LowR3V'in]

I think the same.
Inflating your numbers with fake made up drivetrain % loss
to Brittish HorsePower is bull shit, and just a big guess.

[nando]

the only real way to know would be to dyno an engine on an engine dyno and get a directly flywheel #, and then dyno the same engine in a car on a chassis dyno, which eta said.

the thing is - at the end of the day, the only thing that really matters is wheel horsepower, and how fast your car goes (or doesn't go) down a track.

[LowR3V'in]

When I first got into cars, I'd see dynos that were pretty amazing
compared to dynos here in the US.
"This guy is making 120hp in the uk with his 2.0 VW, wow!"

Then I learned they convert to brittish horse power, and that's why they
ran slower times with "bigger" numbers. Just rambling don't mind me

Also wondering what is the acceptable rang of drivetrain loss for our cars
and what is it based on (who tested and what did he test?).

Do heavy wheels play into this?

If it does, does this mean I can get more HP from a chassis dyno if I just got lighter wheels (same size tire/rim)?
Same with lighter flywheel. More HP at the chassis dyno?

[nando]

all I'm saying is if the e30 has a 28% drivetrain loss, and my ix is even higher with the awd, my m20 must be making more at the crank than most built S52s (which I know it doesn't, not by a longshot).

[briansjacobs]

Physics does not lie.

physics do not lie, but statics do!

[eta]

The problem with quoting 15-20% drive train loss Nando is that I have yet to see an engine installed on a engine dyno and the power/torque curve that results and the same engine installed in a car and the wheel figures that are then produced. Until I see that, the 15-20% figures that I see quoted in many places, seem like recieved wisdom to me. Also the ammount of heat that comes from the transmission in my car, is conciderable, so a high transmission loss is plausible (although maybe not 28%). At first I did not believe that such a loss is plausible but after conversation with a physist who does alot of engine modelling that drive train losses approching that could be possible for E28/E30's. However the exact figure remains unknown, unitl then I will stick the 28% figure indiacted by my RR day.

Also the the estimated flywheel figures are just that estimated. The wheel figures are real. I know this because being a little sad I have created a spreadsheet that uses the wheel curve that I have to determine acceleration in any gear against time. The spreadsheet actually starts at a given speed therefore a given rpm depending on the gear ratio selected. Thus knowing the wheel power, acceleration can be determined and therefore the time taken to the next time point, 0.1 secs later and the new speed. The iterative process continues for as long as I can be bothered to copy and paste. Air resistance and rolling resistance is factored in.

As I have the wheel figures for my car and gear ratio details, I can predict 30-70 time in 3rd and 50-70mph time in 4th. They are exactly what I observe on road testing. So The wheel figures I have posted for my car are real @125whp, not alot I grant you but the same as the eta produced at the flyhweel when it was new. Given I have the stock eta exhaust system and the other E30 based conversions I posted are running custom exhaust setups I don't think the wheel power figures I have given (for the first two plots Dalimerman and the second one) are too high at 135-140 whp. What the actual drive train loss is, is of no concern to me as its the wheel figures that matter, hence the reverse calculation for some of the plots.

Physics does not lie. I do try to have a basis for the numbers I post and although some of them are estimates, I think they are real.

[ForcedFirebird]

yes we do, the past few months my youngest has been awful and is wearing us both out. As soon as she stops being a bitch I will go out at nights again. Yes I just called my 9 month old a bitch!

We have 4 kids, know the routine ;) Oldest is 12, youngest is 4.

[briansjacobs]

another QFT, Brian!

Man, we need to meet up sometime :p

.

yes we do, the past few months my youngest has been awful and is wearing us both out. As soon as she stops being a bitch I will go out at nights again. Yes I just called my 9 month old a bitch!

[briansjacobs]

another QFT, Brian!

Man, we need to meet up sometime :p

I have flowed the same heads on my same flow bench with and without re-calibration in the same day and came up with slightly different results, but the jist is the numbers are close enough for comparison results, this is why I always use % gain over stock as comparison for my racing heads. Competitors show that the stock heads flow generally (stock for stock) more than my bench says, but somehow the heads leaving here equal or better theirs even with my "low numbers (yes I am still at my shop 8:30 at night, prolly be here till 12-1am, and have to go to my 7am construction job in the morn)...

I have run the same car on two different dynos and showed 180hp on one and 165 on the other. I can see 15 hp difference at 500, but at less than 200 I just dont care anymore. All I look for at this point is AFR, how much more power can I make and still be safe?

I have a wide band at the collector that plugs in directly to the dyno, no sniffer tube for me. I found the difference to be 11.9 with the wide band vs 12.4 with the probe at WOT, still safe but not optimal.

[briansjacobs]

Nice curves, Brian, what are you 36-24-36? hehe

36-24-36? only is she is 5'3"

[ForcedFirebird]

did you notice on mine I posted no numbers and only showed the curve? numbers are bull shit unless you are using the exact same dyno (not same kind using same software version) on the exact day at close to the same time. I have done the same car on different days on the same dyno and got different readings.

another QFT, Brian!

Man, we need to meet up sometime :p

I have flowed the same heads on my same flow bench with and without re-calibration in the same day and came up with slightly different results, but the jist is the numbers are close enough for comparison results, this is why I always use % gain over stock as comparison for my racing heads. Competitors show that the stock heads flow generally (stock for stock) more than my bench says, but somehow the heads leaving here equal or better theirs even with my "low numbers (yes I am still at my shop 8:30 at night, prolly be here till 12-1am, and have to go to my 7am construction job in the morn)...