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2Addicts | BMW 2-Series forum Technical Topics N55 (M235i) Engine, Transmission, Exhaust, Tuning Went to the drag strip

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      08-22-2019, 10:57 PM   #1
AmuroRay
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Went to the drag strip

13.6 @106mph - FBO, no tune, 93oct 6 speed manual

13.0 @108mph - above + JB4 map 5.
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      08-23-2019, 08:12 AM   #2
c-m
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I'm FBO 93oct Stage 2 BM3.

I ran 13.0 @ 108mph as well. ZF8 auto F23.
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      08-23-2019, 08:38 AM   #3
abundleofbunnies
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Quote:
Originally Posted by c-m View Post
I'm FBO 93oct Stage 2 BM3.

I ran 13.0 @ 108mph as well. ZF8 auto F23.
nice numbers and good to see a fellow m235i convertible.

whats your experience with the BM3?

and what Bolt ons do you have?

also have you found a good exhaust system that works on the F23 chassis?
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      08-23-2019, 09:16 AM   #4
AmuroRay
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Another M235i was FBO, Auto, some race gas and JB4 Map 5 - 12.2@113
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      08-23-2019, 10:33 AM   #5
XutvJet
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Looking at your 1/4 mile trap speeds, mods, and location, it looks like you were running in some pretty hot and humid Florida August air. Also, since that other M235 auto did 113mph with race gas, it looks like your M235 was suffering from a good bit of heat soak, possible detonation/knock, and power reduction. I imagine running in cooler and drier air will put you in the 111-113mph range as well.

You 60 foots don't sound great either given your 1/4 mile times. Looks like a lot of spin off the line.

What were your 60 foots? I'm guessing upper 2.2s to 2.3s, possibly worse.

What rpm do you shift at?
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      08-23-2019, 10:50 AM   #6
AmuroRay
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Originally Posted by XutvJet View Post
Looking at your 1/4 mile trap speeds, mods, and location, it looks like you were running in some pretty hot and humid Florida August air. Also, since that other M235 auto did 113mph with race gas, it looks like your M235 was suffering from a good bit of heat soak, possible detonation/knock, and power reduction. I imagine running in cooler and drier air will put you in the 111-113mph range as well.

You 60 foots don't sound great either given your 1/4 mile times. Looks like a lot of spin off the line.

What were your 60 foots? I'm guessing upper 2.2s to 2.3s, possibly worse.

What rpm do you shift at?

Ehhhh, I was cutting 2.0 60fts, he was hitting 1.9 (which for every 10th, it's about 2 seconds off the ET) The Auto also was pretty consistent with his times.

But we did do multiple runs back to back - so I don't doubt there was some heat soak. In fact, one run the car stumbled...like hesitated/paused in the middle of 3rd - I hit 13.2 @ 105 on that run.
I shifted at about 6800RPM in 1st - 6500RPM 2nd and held as long as I could for 3rd.

All said and done, I think I ran 7 times. And from what I've seen here, these mods, zero prep and running a JB4/Manual, I'm in line or quicker than most.
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      08-23-2019, 11:30 AM   #7
XutvJet
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Quote:
Originally Posted by AmuroRay View Post
Ehhhh, I was cutting 2.0 60fts, he was hitting 1.9 (which for every 10th, it's about 2 seconds off the ET) The Auto also was pretty consistent with his times.

But we did do multiple runs back to back - so I don't doubt there was some heat soak. In fact, one run the car stumbled...like hesitated/paused in the middle of 3rd - I hit 13.2 @ 105 on that run.
I shifted at about 6800RPM in 1st - 6500RPM 2nd and held as long as I could for 3rd.

All said and done, I think I ran 7 times. And from what I've seen here, these mods, zero prep and running a JB4/Manual, I'm in line or quicker than most.
2.0s are pretty dang good. Heat soak and poor density altitude (density altitude) conditions must have really been impacting your runs as well as the power stumble (likely a knock or overboost event; quite common with the JB4).

A stock 6MT M235 is a 13.3-13.5@106-107mph car in standard DA conditions (60 degrees, low humidity, sea level). With your mods, the car should be trapping 111-113mph pretty easily. These cars do suffer in hot/humid air and on regular 91-93 octane gas, a heat soaked N55 loses out on a good amount of power above 5000rpms. Your JB4 was probably pushing the N55 a bit too hard and causing some knock/overboost, thus the power reduction. The M235 running race fuel was far better off in conditions like that and wasn't suffering from much power reduction because the knock potential is greatly reduced running higher octane fuel.

You're also shifting a bit to early. You should be shifting at 7000rpms in all the gears. Those are the ideal calculated shift points.

This is why I gave up running my cars at the strip in hot/humid air. It's just disappointing. With prior cars I drag raced, the cars were nearly 0.5 seconds and 4-5mph slower running in 85+ humid air vs running on a 60 degree dry day. Absolutely no changes in 60' or mods too. Simply a difference in DA.
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Last edited by XutvJet; 08-23-2019 at 12:39 PM..
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      08-23-2019, 12:10 PM   #8
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      08-23-2019, 12:44 PM   #9
AmuroRay
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Is map 5 better than Map 2 on pump? Is Map 2 close to an M2 in power?
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      08-23-2019, 05:08 PM   #10
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Iím in the south with 93 degree weather. Heat soak for sure.
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