Subtraction by Addition: CHECK! Sometimes I hate my car - Page 5 - The Unofficial BMW M5 Messageboard (m5board.com)

jrhaile · 6th July 2009, 21:35

Quote:

Originally Posted by ECB

Not to get into a 3.15 vs 3.45 debate, but there are countless posts by members much smarter than I that question the benefit of 3.45 gears in our cars. Just a few:

3.45 diff - hard data on acceleration improvement?

3.45 diff - hard data on acceleration improvement?

3.45 diff - hard data on acceleration improvement?

Another friend of Aaron and mine during a drunk moment of his basically said there will be LITTLE to no difference in turns of revolutions going with the 3.45 from a 3.15. And it's pretty evident by our races that he is absolutley correct. I'm going to be doing 3.62 or maybe even 3.73 gears for a difference in torque at ALL RPMs.

I'm sure Aaron will agree with this, but this seems to be another case of Dinan "engineering" being overrated. Maybe a true test would be to see how we measure at MPH wise at the 1320 here in town. I have no doubt in my mind I could probably beat him off the line as I've drag raced my M5 probably 40-50 passes where as he's done zero in his so only a MPH rating would be a good test.

Another friend of mine just bought a stock M5 so when he comes back into town, it would be interesting to see us all 3 run and see how things stack up. Problem is, the other car just purchased needs a bit of maintenance (cps and MAFs).

One final note.. back in April, Aaron (Churious) dynoed 20whp more and 15ftlbs more than me on the same day on the same dyno. Switching to a more HP happy dyno (which this thread is based on) I still haven't dynoed the same number he put down back in April on a dyno that is known to read 8-10% lower in town.

gsfent · 6th July 2009, 21:54

Quote:

Originally Posted by jrhaile

I will tell you what (hick talk) but going with the Borla mufflers and Highflow cats in my butt sure made a HUGE difference on the top end. I noticed it right away.

No matter how finely calibtrated your butt is,

, the real test is what a dyno says. And I mean a comparison of before and after on the same dyno!!
In your case, your butt is feeling the gain, but the dyno (presumably the same, different day, but both SAE corrected) says you lost peak hp.

Now, you may have flattened out the power curve, or it may be that since you lost power in the lower rpms, it now feels faster in comparison when you get to higher rpms.

In adding exhaust, your gains will be sound and weight savings. Race cats may add 5-10 hp on a good day. So your setup with race cats may not be ideal ( a total system working in harmony, like say, the SS headers and race cats, which Evosport showed about a 10 hp gain IIRC).

But if it sounds good, and it feels good, then nothing wrong with it!!

If you want significant power, you need headers, at least IMHO.

Regards,
Jerry

jrhaile · 6th July 2009, 21:58

Quote:

Originally Posted by gsfent

No matter how finely calibtrated your butt is,

, the real test is what a dyno says. And I mean a comparison of before and after on the same dyno!!
In your case, your butt is feeling the gain, but the dyno (presumably the same, different day, but both SAE corrected) says you lost peak hp.

Now, you may have flattened out the power curve, or it may be that since you lost power in the lower rpms, it now feels faster in comparison when you get to higher rpms.

In adding exhaust, your gains will be sound and weight savings. Race cats may add 5-10 hp on a good day. So your setup with race cats may not be ideal ( a total system working in harmony, like say, the SS headers and race cats, which Evosport showed about a 10 hp gain IIRC).

But if it sounds good, and it feels good, then nothing wrong with it!!

If you want significant power, you need headers, at least IMHO.

Regards,
Jerry

I hear ya on the headers part. My problem is now, I blew out a shock yesterday on the track so I need to do Coilovers first and then rebuild my rear with different gears because it's starting to make a howling noise. After that, headers...

jt2ma71 · 6th July 2009, 22:32

I know its kinda ricer-ish math, but the only way to compare. Your 0-80mph is knocking around the 8 second range, and you were going faster then 0mph, its hard to tell but id say you were maybe 10mph or faster. Ive timed other E39 M5's including my own and from a stop till 80mph i pegged about 7.3 and that is with 20x10's, that are boat anchors, and K&N filters with stock MAFS that were recently cleaned otherwise unknown in terms of age. There is one on youtube, from what i read, tubi exhaust, and quite possibly SS headers doing 6.30-6.5. Look up DESIGNM5

I just realized your in Spokane. Im like 15 minutes from the Peace arch crossing. I may be heading to Seattle sometime soon with a few friends, interested in doing some freindly runs?

xr4tic · 7th July 2009, 05:34

on paper, the 3.45 gear is faster than the 3.15 gear from 30 to 60/90/120 and 60 to 90/120 - http://vlsicad.ucsd.edu/~sharma/Potpourri/perf_est.html
The 3.62 is slower in some situations

I plugged in the values from this thread - E39 M5 dyno results with graphs - U.S. Specs adjusted by 10% to get crank HP
3800 lbs, 0.31 drag, 24 ft^2 frontal area, 275/35/18 tires

I got the following: 3.15 vs. 3.45 vs. 3.62
30-60.....2.35....2.20...2.70
30-90.....6.50....6.35...6.25
30-120..12.75..12.50..13.10
60-90.....3.85...3.65....3.60
60-120..10.10...9.85..10.45

The 3.62 is slower because of the extra shifts.

jt2ma71 · 7th July 2009, 06:00

Quote:

Originally Posted by xr4tic

on paper, the 3.45 gear is faster than the 3.15 gear from 30 to 60/90/120 and 60 to 90/120 - http://vlsicad.ucsd.edu/~sharma/Potpourri/perf_est.html
The 3.62 is slower in some situations

I plugged in the values from this thread - E39 M5 dyno results with graphs - U.S. Specs adjusted by 10% to get crank HP
3800 lbs, 0.31 drag, 24 ft^2 frontal area, 275/35/18 tires

I got the following: 3.15 vs. 3.45 vs. 3.62
30-60.....2.35....2.20...2.70
30-90.....6.50....6.35...6.25
30-120..12.75..12.50..13.10
60-90.....3.85...3.65....3.60
60-120..10.10...9.85..10.45

The 3.62 is slower because of the extra shifts.

Cool numbers to know. If my freakin car could pass smog right now, i would test out those numbers and see how close mine are!

from my old videos, im about dead on, in terms of the 30-90 and 30-120, but the 30-60 im way off, im at like 3.2-3.2 seconds. Even in other videos, ive never seen a M5 video where it goes 30-60 in 2.2 seconds unless its wheels are spinning

jrhaile · 7th July 2009, 08:12

Quote:

Originally Posted by jt2ma71

I know its kinda ricer-ish math, but the only way to compare. Your 0-80mph is knocking around the 8 second range, and you were going faster then 0mph, its hard to tell but id say you were maybe 10mph or faster. Ive timed other E39 M5's including my own and from a stop till 80mph i pegged about 7.3 and that is with 20x10's, that are boat anchors, and K&N filters with stock MAFS that were recently cleaned otherwise unknown in terms of age. There is one on youtube, from what i read, tubi exhaust, and quite possibly SS headers doing 6.30-6.5. Look up DESIGNM5

I just realized your in Spokane. Im like 15 minutes from the Peace arch crossing. I may be heading to Seattle sometime soon with a few friends, interested in doing some freindly runs?

Aaron we need to invest in a VBox.

I'm about 280 miles from Seattle

I'd love to do some runs but I don't make it to Seattle as often as I'd like.

churious · 7th July 2009, 08:19

Quote:

Originally Posted by jrhaile

Aaron we need to invest in a VBox.

I'm about 280 miles from Seattle

I'd love to do some runs but I don't make it to Seattle as often as I'd like.

Vbox?

jrhaile · 7th July 2009, 08:20

Quote:

Originally Posted by xr4tic

on paper, the 3.45 gear is faster than the 3.15 gear from 30 to 60/90/120 and 60 to 90/120 - http://vlsicad.ucsd.edu/~sharma/Potpourri/perf_est.html
The 3.62 is slower in some situations

I plugged in the values from this thread - E39 M5 dyno results with graphs - U.S. Specs adjusted by 10% to get crank HP
3800 lbs, 0.31 drag, 24 ft^2 frontal area, 275/35/18 tires

I got the following: 3.15 vs. 3.45 vs. 3.62
30-60.....2.35....2.20...2.70
30-90.....6.50....6.35...6.25
30-120..12.75..12.50..13.10
60-90.....3.85...3.65....3.60
60-120..10.10...9.85..10.45

The 3.62 is slower because of the extra shifts.

Seems to me Dinan inputed the same data and went with it.. it's imo, clearly not correct.

jt2ma71 · 7th July 2009, 08:48

Quote:

Originally Posted by jrhaile

Aaron we need to invest in a VBox.

I'm about 280 miles from Seattle

I'd love to do some runs but I don't make it to Seattle as often as I'd like.

Ahh that sucks. Well i was planning a road trip to Oregon. If i do il make sure i drive thru spokane! Or if your ever up in BC, ill do some freindly runs, i know lots of areas to run + take pics!