Dyno trouble shooting session of Z4M ESS VT - 525

[exdos]

Originally Posted by gmd2003

Here is my fastest session of the day with a 1:20.5 lap. Me and a 2400 pound E30 were tearing through the field . I slowed down to let him by at the end so i could get him on film. He was a great driver , and a little crazy lol.

It was interesting to focus on the position of the gear lever during cornering: you can see how the engine and transmission rotates during cornering with lateral loading. Do you have Vibra Techic engine mounts?

Why do you always change down into fourth gear mid corner on the corner after the main straight, rather than before entering the corner?

[gmd2003]

I do have the engine mounts , it's much much better than before . At the end of the straight I'm at redline in 5th at 150 mph and found that it is much smoother turning into 1 and easier to modulate the throttle in the turn in 5th . I have 4:10 gears also so if I downshift to 4th in my breaking zone I will be downshifting to redline which is very tough to do smoothly . Just what works best for me at these speeds with my cars gearing and torque .

[tikamak]

Originally Posted by gmd2003

I do have the engine mounts , it's much much better than before . At the end of the straight I'm at redline in 5th at 150 mph and found that it is much smoother turning into 1 and easier to modulate the throttle in the turn in 5th . I have 4:10 gears also so if I downshift to 4th in my breaking zone I will be downshifting to redline which is very tough to do smoothly . Just what works best for me at these speeds with my cars gearing and torque .

Any news? were you able to find out the source of the limp mode?

I've never had a limp mode with my car but i never stressed it enough to get to that point.

[gmd2003]

Originally Posted by tikamak

Any news? were you able to find out the source of the limp mode?

I've never had a limp mode with my car but i never stressed it enough to get to that point.

It's more of a safe mode , as the engine is completely killed to idle with no throttle input . It is related to the ECU seeing boost in the vacuum system . ESS is still working on a solution . I've learned ways to drive around it and still be very fast , but it does limit me in a few spots on track .

[gmd2003]

Here is some data from my testing of the car with my Vbox sport . Of course it is a flat slope . Traction was a major issue, to the point I'm sure it hurt my speed at the 1/4 as well as ET , despite running Hankook TD R comps . I guess what I'm a little disappointed in is the 60-130 time of 10.45 sec . With my 4.10 gears it requires 2 shifts which slows it down a good bit . My best 1/4 speed was 118 which is good , just expected the car to be in the 9's 60-130 . At the End I posted my run in my stock CP M6 coupe for comparison . ( there isn't any it would destroy the Z4M) 8.09 60-130 , and a traction limited 11.8@ 128.3 mph !!!

[VMZ432]

Can you get a comparison of the M6 to Z4M for 60 - 110 with your existing data? I guess it would be meaningless if the M6 is changing gears twice in that time, but from your comments it sounds like it's not?

I'd love to see a lap time comparison between your M6 and Z4, same driver, comparable conditions. Think that will ever happen?

Thanks for sharing.

[gmd2003]

Originally Posted by VMZ432

Can you get a comparison of the M6 to Z4M for 60 - 110 with your existing data? I guess it would be meaningless if the M6 is changing gears twice in that time, but from your comments it sounds like it's not?

I'd love to see a lap time comparison between your M6 and Z4, same driver, comparable conditions. Think that will ever happen?

Thanks for sharing.

The M6 is over a full second faster from 60-100 . It feels way faster and it is . The crazy thing is it's 2.3 sec faster 60-130 that's rape. Certainly the DCT helps but it's faster in gear as well . I haven't tracked the M6 yet . My Z4M is set up for the track but even so it would be close on a power track like VIR . On a technical track like Roebling the Z4M would kill it .
George

[ZStig]

I layed down a 12.16@116.8 as my best 1/4 mile time, on 7psi of boost with the VT2-500 kit

I'm surprised your trap speed is so low. I think you're losing most of your 1/4 mile time in the 0-60. I got a 4.2 second 0-60 before on a Vbox, probably lower on the quarter mile track

[ZStig]

did you ever dyno beyond 400rwhp? I didn't go over your 10 pages of thread recently

[gmd2003]

Originally Posted by ZStig

I layed down a 12.16@116.8 as my best 1/4 mile time, on 7psi of boost with the VT2-500 kit

I'm surprised your trap speed is so low. I think you're losing most of your 1/4 mile time in the 0-60. I got a 4.2 second 0-60 before on a Vbox, probably lower on the quarter mile track

Well 118 isn't bad , especially with excessive 1st and 2nd gear spin that I had( the 115 run I wasn't trying to launch just to get the best 60-130) . I'm def full 525 spec + , I'm running SS v2 stepped headers and DKF catless s pipe . I just thought it would be faster up top 60-130 mph , it got trounced by my 2014 CP M6 . Even removing my two shifts .5 sec each ( to negate the DCT factor) the M6 is still 1.2 sec faster if the cars had the same shift time .

[gmd2003]

Originally Posted by ZStig

did you ever dyno beyond 400rwhp? I didn't go over your 10 pages of thread recently

Yes I'm in the 440whp range running the correct belt and pulleys .

[ZStig]

hmm, and what about the M6 dyno?

[gmd2003]

Originally Posted by ZStig

hmm, and what about the M6 dyno?

The dynos of it are all over the place from other people from 500whp to 580 whp stock , and after the trouble my local dyno had with my old SMG M6 I don't want to bother . I think the 128 mph 1/4 and the 8 sec 60-130 tells the story pretty well . Its got a massive AUC advantage . It's a legit 500lb feet of torque to the wheels from 2-6k and 550- 580whp from 6-7k judging from the data available . That's hard to beat . So the Z4M is over 100 whp and 200 wtq and actually has less favorable aero . So at high speeds where power is king I guess it makes sense .

[ZStig]

Oh its a NEW m6. Now that makes more sense

[VMZ432]

Originally Posted by gmd2003

The dynos of it are all over the place from other people from 500whp to 580 whp stock

Weird. I though it was only 575hp at the crank. So about 488whp. But if that were true your Z4M would trounce it on hp per tonne..... so I guess 575hp at the crank is an underestimate.

If you are on a relatively low traction surface (ie. not a drag strip) the weight of the M6 should help give it more advantage. No doubt you have taken that into account.

FYI, I have tried doing aggressive launches with the VT2 and had massive clutch slip (my stock clutch has only done about 22k miles). Would not recommend pushing it too hard unless you are keen to replace your clutch. I don't think you'll get anywhere near the cars full potential with the stock clutch on the strip, though it's fine on the track as you know. Wheel spin might be the only thing saving you at the moment.

[gmd2003]

Originally Posted by VMZ432

Weird. I though it was only 575hp at the crank. So about 488whp. But if that were true your Z4M would trounce it on hp per tonne..... so I guess 575hp at the crank is an underestimate.

If you are on a relatively low traction surface (ie. not a drag strip) the weight of the M6 should help give it more advantage. No doubt you have taken that into account.

FYI, I have tried doing aggressive launches with the VT2 and had massive clutch slip (my stock clutch has only done about 22k miles). Would not recommend pushing it too hard unless you are keen to replace your clutch. I don't think you'll get anywhere near the cars full potential with the stock clutch on the strip, though it's fine on the track as you know. Wheel spin might be the only thing saving you at the moment.

The M6 is actually more traction limited than the Z4M . My 0-60 time was better in the Z4M . The M6 is just that much faster up top . Yeah I think the 575 crank is on top of a mountain on a 100 degree day lol . You don't hit 8 sec 60-130 or 128 mph GPS in the 1/4 in a 4200 pound car with only 480whp . Yeah I figured a real launch would cause clutch slip , but on track it's done great on the stock clutch . 20,000 track miles and counting . The combination of high RPM power band , short wheelbase , and great steering feel make the FI Z4M a killer on track . Taking down a fellow advanced driver in a 997.2 GT3 RS on slicks is proof of that . It's a perfect track car . I honestly couldn't use more power in most tracks . Hitting 150mph GPS on a .6 mile straight is fast enough for me !

[Str8 RippiN]

updates? ESS?

[Beedub]

tika had an interesting theory on these limp mode issues / break booster that i think may be actually founded.... ill let him explain....

[tikamak]

Originally Posted by Beedub

tika had an interesting theory on these limp mode issues / break booster that i think may be actually founded.... ill let him explain....

It's not actually a theory, it's more like something i noticed when snooping around my engine bay as always.

Some S54s for Z4M have this item down there, and some other don't have it.

This below is my car, beedub please post a picture of your fuel rail so taht people can notice how you don't have what i have in my car.

[Woots]

Isn't that just the difference between yank and Brit cars?

[tikamak]

Originally Posted by Woots

Isn't that just the difference between yank and Brit cars?

E46 M3s don't have that. check some S54 pics online. it's a bit wierd :S

I'm not able to find the fuel rail part number that has a T with a valve in it towards the top of the cylinder head, where all the steam escapes (is that PCV or ICV or something like that)

[Beedub]