BM3: Stage 2 with out DP?

[M 4 FUN]

Originally Posted by RElias21

What made you decide to run Stage 2 with 20% reduction rather than just run Stage 1?

Any benefit over Stage 1 at that point?

There is a couple of reasons: One is that my car is manual and i feel that the car just more difficult to Control when you push it in corners with over 700 Nm of torque. The only thing that happens is that you loose grip easier and you get slower. I Think i'm faster on a track now then with full torque.

Another reason is that the caracter of the engine gets more like a normally aspirated engine. Instead of have a more diesel like caracter with a lot of torque coming early and then sign off i prefer that the car is more linear in the powerband. Now the boost increases all the way up to 7000 rpm.

Another thing is that i want to be keep my car for a long time and lower torque saves the whole drivetrain in the long run.

And i'm no drag racer either so i don't care if i do 0-whatever 2 tenths faster.

[M 4 FUN]

Originally Posted by ntg44

Stage 2 has a higher torque peak, with more high RPM torque than stage 1, so when you run 20% reduction on stage 2, the tune cuts 20% from the peak torque of the tune, not the entire rev range, so you'll have a flatter torque curve for longer as you approach redline. The torque eventually tapers, but later than stage 1 since the high RPM torque is higher.

A simple way to understand it is look at the dyno sheet of stage 1 vs 2 on the same sheet. For a 20% reduction, multiply the peak torque of stage 2 by 80% and draw a straight horizontal line on the sheet at that 80% value in MS Paint. You'll see the torque remains constant at that level until the high RPM taper. You'll notice that stage 1 torque drops at an earlier RPM than stage 2, and pushing that taper off as far right as possible (which means at as high of an RPM as possible) gives the tune a more consistent feel of power delivery for longer.

Running torque reduction this way, you don't get that midrange torque explosion that's most likely going to cut throttle from traction control, followed by a huge dropoff after ~5500 RPM. I notice this on the stock base model tune as well. The stock tune has more of a flat hp curve than a flat torque curve, which means the torque is dropping off significantly as redline is approached. And I absolutely do feel it, for me it's not desirable. For my preference, the stock midrange torque is perfect, so if I had a tune, I'd put on stage 2 with x% reduction down to stock mid range output, just so I can get the benefits of the consistent torque delivery to almost near redline. Tunes are much more than just about peak numbers, and the benefit of BM3 reduction is you can basically tune how you want the pull to feel, which is awesome.

Exactly. I agree fully. I really like it the way it is now.

[papasmurf_m3]

I wouldn't do that... Main advantages of downpipe are flow and heat extraction. Yes, E85 runs much cooler but, still going to be trapping more heat. Heat is the enemy so get it out of the engine as fast as possible

[M 4 FUN]

Originally Posted by papasmurf_m3

I wouldn't do that... Main advantages of downpipe are flow and heat extraction. Yes, E85 runs much cooler but, still going to be trapping more heat. Heat is the enemy so get it out of the engine as fast as possible

I can't see that there is so much restriction. If there was a problem with that the car would react immediately to that and either lower boost or retard timing. Nothing of this happens. It would also be shown on the dyno numbers, which it doesn't as shown in the text i posted from Ptf. My log shows 22 psi at 7000 rpm. A friend of mine dynoed his M3 on E85, running 28PSI and Close to 600 whp, also with stock downpipes. His logs were perfect too, no problems at all. But it's up to everyone to do and Think what they want .

[heliskiier]

Originally Posted by ntg44

Stage 2 has a higher torque peak, with more high RPM torque than stage 1, so when you run 20% reduction on stage 2, the tune cuts 20% from the peak torque of the tune, not the entire rev range, so you'll have a flatter torque curve for longer as you approach redline. The torque eventually tapers, but later than stage 1 since the high RPM torque is higher.

A simple way to understand it is look at the dyno sheet of stage 1 vs 2 on the same sheet. For a 20% reduction, multiply the peak torque of stage 2 by 80% and draw a straight horizontal line on the sheet at that 80% value in MS Paint. You'll see the torque remains constant at that level until the high RPM taper. You'll notice that stage 1 torque drops at an earlier RPM than stage 2, and pushing that taper off as far right as possible (which means at as high of an RPM as possible) gives the tune a more consistent feel of power delivery for longer.

Running torque reduction this way, you don't get that midrange torque explosion that's most likely going to cut throttle from traction control, followed by a huge dropoff after ~5500 RPM. I notice this on the stock base model tune as well. The stock tune has more of a flat hp curve than a flat torque curve, which means the torque is dropping off significantly as redline is approached. And I absolutely do feel it, for me it's not desirable. For my preference, the stock midrange torque is perfect, so if I had a tune, I'd put on stage 2 with x% reduction down to stock mid range output, just so I can get the benefits of the consistent torque delivery to almost near redline. Tunes are much more than just about peak numbers, and the benefit of BM3 reduction is you can basically tune how you want the pull to feel, which is awesome.

Tell me more. I just put my intercooler in and running BM3 stage 1 93. How much of a difference is there between stage 1 and 2 with your torque reduction? Is it relatively safe or my stock downpipe? Thanks!

[Juny]

Interesting.

[M 4 FUN]

Originally Posted by heliskiier

Tell me more. I just put my intercooler in and running BM3 stage 1 93. How much of a difference is there between stage 1 and 2 with your torque reduction? Is it relatively safe or my stock downpipe? Thanks!

I chime in here. I run stage2 93 octane and have been doing that for three years now with stock downpipes. No problems whatsoever. Perfect on logging, no retarded timing or anything. No noticeable power loss, no bad smoke, goes through inspection as a stock car, sounds better in my opinion, no extra cost for downpipes and work.

[Gunzy]

I do the same as M 4 FUN and agree with everything he said.

[heliskiier]

Originally Posted by M 4 FUN

I chime in here. I run stage2 93 octane and have been doing that for three years now with stock downpipes. No problems whatsoever. Perfect on logging, no retarded timing or anything. No noticeable power loss, no bad smoke, goes through inspection as a stock car, sounds better in my opinion, no extra cost for downpipes and work.

Do you get a noticable power increase staying with the stock pipe and stage 2?

[M 4 FUN]

Originally Posted by heliskiier

Do you get a noticable power increase staying with the stock pipe and stage 2?

Sorry for late reply!
I haven't run any other map than stga 2 93 octane so i can't compare but the power difference between stage one and two is about 2 percent.

[ByeFelicia]

Originally Posted by M 4 FUN

Sorry for late reply!
I haven't run any other map than stga 2 93 octane so i can't compare but the power difference between stage one and two is about 2 percent.

Hey could you answer this question?

Just to be clear, when you say 20% torque reduction, are you talking about boost reduction by gear? if so, did you reduce it in every gear?

I have manual as well and considering stage 2 and keeping my oem cats after reading your posts.

Just want to try the 20% reduction method as well.

And yea if you reduced 20 in every gear?

[Wanted_M]

If Kies can push close to 1000hp with all four stock cats, I think it can easily handle stage 2.
https://youtu.be/wpQn9raK5vo

[M 4 FUN]

Originally Posted by ByeFelicia

Hey could you answer this question?

Just to be clear, when you say 20% torque reduction, are you talking about boost reduction by gear? if so, did you reduce it in every gear?

I have manual as well and considering stage 2 and keeping my oem cats after reading your posts.

Just want to try the 20% reduction method as well.

And yea if you reduced 20 in every gear?

Hi!

yes, i reduced it in every gear. You can call it boost by gear but the treshold is the torque limit so the engine builds boost up to the set torque limit. Boost curve is slightly climbing up all the way to 7000 rpm to still deliver the max power output as a regular stage two map has so no peak power is lost. I really like the caracter when the engine never stops pulling on higher revs instead of signing off like a diesel .

[headstart101]

Over a year on stock DPs running E30 tune. Zero issues and logs are always clean.

[HotRodM4]

You guys definitely got me interested in running 20% reduction for a better feel and control. I’m usually on stage 2 w/ stock downpipes. Thinking about trying out the multimap and doing the 20% torque reduction through all gears if it allows me to do so on the multimap. Otherwise I’ll do it on stage 2.

Curious though, can you guys still easily do burnouts and slides when you want to with the reduction?

[M 4 FUN]

Originally Posted by HotRodM4

You guys definitely got me interested in running 20% reduction for a better feel and control. I’m usually on stage 2 w/ stock downpipes. Thinking about trying out the multimap and doing the 20% torque reduction through all gears if it allows me to do so on the multimap. Otherwise I’ll do it on stage 2.

Curious though, can you guys still easily do burnouts and slides when you want to with the reduction?

Haha, yeah, don't worry about not being able to slide . I still got 620 Nm at the wheels so if you want to play and slide there is no problems with that .

[Gunzy]

It is a recommended decision. You do not need upgraded dp (marketing hype) to run more boost (20psi vs 23psi?) it’s a marketing hype and not necessary. It’s just a boost number, if you run too much pressure through an exhaust (what?) it’ll just slow it down, not blow up your motor.

[M 4 FUN]

I throw up my dynosheet from when i had done the 20% torque reduction.
As said, EVERYTHING else is stock, the car came with full M performance options from BMW which includes M performance titanium exhaust system so that is on the car. Power is wheel horsepower. Note that torque is in Newtonmeters. Look at that beatiful torqe curve :

[M 4 FUN]

Comparison with my friends M3 who ran catless downpipes and E30 mix and no torque reduction. I thought downpipes and E30 mix would make more difference on power but the dyno doesn't lie
Only 16 hp difference. That says a lot about how good the stock downpipes flows:

[HotRodM4]

Originally Posted by M 4 FUN

Haha, yeah, don't worry about not being able to slide . I still got 620 Nm at the wheels so if you want to play and slide there is no problems with that .

Originally Posted by M 4 FUN

I throw up my dynosheet from when i had done the 20% torque reduction.
As said, EVERYTHING else is stock, the car came with full M performance options from BMW which includes M performance titanium exhaust system so that is on the car. Power is wheel horsepower. Note that torque is in Newtonmeters. Look at that beatiful torqe curve :

It’s been a few days since I flashed 20% torque reduction through all gears on stage 2.

Car feels easier to control and I have more confidence kicking out the rear on turns for fun 😄 Really liking it so far.

[boogiePls]

Damn that torque curve looks great! Looks like I’ll be going stage 2 with the torque % reduction, thanks for sharing M 4 FUN!

[HotRodM4]

Originally Posted by boogiePls

Damn that torque curve looks great! Looks like I’ll be going stage 2 with the torque % reduction, thanks for sharing M 4 FUN!

I also notice that when if I downshift and let the car roll without gassing it, it still feels like it’s on boost. Like there’s no drop off in power. I’m liking this 20% torque limit.