Z3M V8 Conversion

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exdos
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Post by exdos » Thu 16 Feb, 2012 11:45

Deano,

You've not actually made the silencer any more free flowing than in OEM state. You've cut into the outlet pipes at the wrong end.
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Deano1712
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Post by Deano1712 » Thu 16 Feb, 2012 13:06

Dont agree at all. There are large holes in the two bulkheads so plenty of free area to get the air to the forward end of the outlet tubes. Cutting out the secondary tubes frees one restriction and opening up the free area of the perforated area of the outlet tubes clears the other.

I suppose the other option would be to cut slots at the rear of the outlet tubes but the free area is the same. The air would have a more direct path (no reversal) but I dont think this would make much difference.
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exdos
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Post by exdos » Thu 16 Feb, 2012 13:21

If you stood the silencer vertical so that the tail pipes are pointing down at the lowest point and poured water into the the silencer through the inlet pipe, the two lowest chambers would fill before any water could exit via the outlet pipes, so your modded silencer still works by "reverse flow", and "free flow" is what you should be aiming for.

I've done lots of experimentation with ECU datalogging of modified ZM exhausts of various configurations (described on z3mcoupe.com) and I know that your mod will not achieve much by way of improvement of flow or sound. Just trying to help :thumb:

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Deano1712
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Post by Deano1712 » Thu 16 Feb, 2012 14:45

I understand what you meant regarding the flow path but I think free area is more of an issue than whether the path is straight of reversed. I will take a look at your posts though.

I have bought an exhaust pressure tester so if the back pressure measures less than 2psi at WOT I will be content.
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Re: Z3M V8 Conversion

Post by Deano1712 » Mon 26 Mar, 2012 19:32

Fitting these babies on the rear this week. Then end of wheel spin I hope lol.

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Badman gee
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Re: Z3M V8 Conversion

Post by Badman gee » Mon 26 Mar, 2012 19:36

they are huge!!!

i bet they cost a bit as well!!
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Re: Z3M V8 Conversion

Post by Deano1712 » Mon 26 Mar, 2012 19:39

Surprisingly not. Ebay job for £150 each. Its going to cost more for 235/40 fronts!
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Re: Z3M V8 Conversion

Post by Robert T » Mon 26 Mar, 2012 20:41

You may be able to get some money back on them by lending to the highways agency to roll roads with. :wink:

They're over a foot across!!!! :shock:

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Re: Z3M V8 Conversion

Post by shantybeater » Mon 26 Mar, 2012 22:09

Holy! Makes my 10J rears look like a smart car! Whats the profile?
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Re: Z3M V8 Conversion

Post by Gazza » Mon 26 Mar, 2012 22:13

Says 315/30 on the label :wink:
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Re: Z3M V8 Conversion

Post by shantybeater » Mon 26 Mar, 2012 22:29

Oh yeah, wheres that dunse smilie!
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Re: Z3M V8 Conversion

Post by Z3cade » Mon 26 Mar, 2012 22:37

Deano have not thought about a new system rather than cutting up the standard exhaust? I'm sure you would get better performance and sound from that lovely V8 with a super sprint and decat or the like.. :wink:
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Re: Z3M V8 Conversion

Post by Deano1712 » Thu 29 Mar, 2012 19:16

Decat would make the car very loud and fail mot too. My rears interface differently with the centre section so I cant simply swap it out with an aftermarket silencer. I did consider making new exhausts myself but I didnt see the value in the effort and cost. I drove the car today believe me it sounds good enough and goes well :shock:

I have the wheels modifed and fitted. Fronts are now 18x8ET32 and rears 18x11.5ET24. The existing 295 rear would have been a bit stretched on the wider rim hence the new tyres. The Michelins look a better tyre than the Falkens and are noticeably lighter.

Suffice to say 315mm rears is certainly the widest tyre that can be fitted to the Z3! The Michelins have a large rim protector which made them wider than I expected and a few adjustmets were needed. Its a chunky look...

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Re: Z3M V8 Conversion

Post by shantybeater » Thu 29 Mar, 2012 19:32

Just....awesome..
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Re: Z3M V8 Conversion

Post by Z3cade » Thu 29 Mar, 2012 19:56

Looks like a dragster.. :twisted:

Bring it to Santa pod this sunday!! :D
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Re: Z3M V8 Conversion

Post by whiteminks » Thu 29 Mar, 2012 20:14

Eeeeeeeeeeeeee them's look like mini tractor toyarrrz t'me............. oooh ahhhhhhhhhh oooh ahhhhhhhhhhhh :wink: :lol: :lol: :lol:
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Re: Z3M V8 Conversion

Post by swamper » Thu 29 Mar, 2012 20:20

bloody hell... :shock:
the badness makes me do it...!

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Badman gee
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Re: Z3M V8 Conversion

Post by Badman gee » Thu 29 Mar, 2012 20:34

very nice, id love a ride in it deano?

at zed fest?

:D

stick me at the top of the list if your taking people for a spin :twisted:
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Re: Z3M V8 Conversion

Post by markrnorton » Fri 30 Mar, 2012 14:07

Looks like you could do some road rolling with those beasty tyres ! flatten that tarmac

How does it affect handling ?
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Re: Z3M V8 Conversion

Post by offyourmarks » Fri 30 Mar, 2012 17:30

Fantastic read :)

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John1950
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Re: Z3M V8 Conversion

Post by John1950 » Fri 30 Mar, 2012 19:22

shantybeater wrote:Oh yeah, wheres that dunse smilie!
Remind me - how does one spell 'dunce'? :dunce:
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Re: Z3M V8 Conversion

Post by John1950 » Fri 30 Mar, 2012 19:22

shantybeater wrote:Oh yeah, wheres that dunse smilie!
Remind me - how does one spell 'dunce'? :dunce:
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Re: Z3M V8 Conversion

Post by Deano1712 » Sat 31 Mar, 2012 15:16

markrnorton wrote:Looks like you could do some road rolling with those beasty tyres ! flatten that tarmac

How does it affect handling ?
Dont know yet. It may make it understeer but I can always adjust the setup now the KWV3's are fitted. At the moment its a scary ride. The new rears are spinning really easily hence not driven it fast. It feels more powerful than it did, and I expect the tyres need a few miles putting on them before they grip.

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Re: Z3M V8 Conversion

Post by Ian_C » Sat 31 Mar, 2012 15:27

Deano1712 wrote: Image
At first glance I thought you had 4 tyres stacked up there Mark - just realised it's only 2 :shock:

Looking forward to seeing the beast on the Yorkshire cruise in a couple of weeks (fuel permitting :head: )
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Re: Z3M V8 Conversion

Post by c_w » Mon 02 Apr, 2012 14:17

Looks ace! 235 / 315 is a bit of a massive differential though, you can go wider at the front too but 8J rim isn't all that wide compared to the rear.

They're Porsche 911 tyres, I imagine the ride is a bit more jiggly with those as the sidewalls will be mega stiff!

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Re: Z3M V8 Conversion

Post by gookah » Mon 02 Apr, 2012 17:25

You can't have been far off getting just one 1800 tyre instead.... :D
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Re: Z3M V8 Conversion

Post by Deano1712 » Mon 02 Apr, 2012 21:23

c_w wrote:Looks ace! 235 / 315 is a bit of a massive differential though, you can go wider at the front too but 8J rim isn't all that wide compared to the rear.
Yes agreed. I can fit 245 up front I think so will probably go with that. Will be better than what I have. I'm looking out for a cheap pair of PS2's.
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Re: Z3M V8 Conversion

Post by offyourmarks » Tue 03 Apr, 2012 06:24

As there is more than enough torque to light the rears, by increasing the contact patch with the wider tyres you are obviously going to increase the torque reaction from the half shafts - do you envisage any chassis structural problems due to the increased loading? :)

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Re: Z3M V8 Conversion

Post by Deano1712 » Tue 03 Apr, 2012 20:56

offyourmarks wrote:As there is more than enough torque to light the rears, by increasing the contact patch with the wider tyres you are obviously going to increase the torque reaction from the half shafts - do you envisage any chassis structural problems due to the increased loading? :)
Good question!
You may remember that I had problems with my boot floor a few years ago and did a strengthening job on it. When I did that I made sure the fix was at least twice as strong as standard. This is the weak point and I'm confident I wont have any more problems there even with the increased torque its now likely to see.
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Re: Z3M V8 Conversion

Post by c_w » Wed 04 Apr, 2012 10:42

The actual BMW drivetrain is good for monster power the weaklink is the body structure and attaching points so like you say if it's been strengthened then it should be fine!

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Re: Z3M V8 Conversion

Post by offyourmarks » Thu 05 Apr, 2012 17:34

Deano1712 wrote:
offyourmarks wrote:As there is more than enough torque to light the rears, by increasing the contact patch with the wider tyres you are obviously going to increase the torque reaction from the half shafts - do you envisage any chassis structural problems due to the increased loading? :)
Good question!
You may remember that I had problems with my boot floor a few years ago and did a strengthening job on it. When I did that I made sure the fix was at least twice as strong as standard. This is the weak point and I'm confident I wont have any more problems there even with the increased torque its now likely to see.
http://www.zroadster.net/forum/viewtopi ... inter+jobs
Ahh yes, i remember that thread a while back.

Interesting read Dean - when doing the numbers did you calculate the loads from the half shaft and the propellor shaft?

When calculating max torque in first, what % efficiency did you estimate when incorporating the final drive and first gear ratios? 85%?

Looking at the geometry of the rear I'd guess that the summed force isnt applied through a single component either onto the ear and beam. Would I be right in thinking the diff ear tears or do the spots pop. Or both?

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Re: Z3M V8 Conversion

Post by Deano1712 » Mon 06 Aug, 2012 22:21

offyourmarks wrote:Ahh yes, i remember that thread a while back.

Interesting read Dean - when doing the numbers did you calculate the loads from the half shaft and the propellor shaft?

When calculating max torque in first, what % efficiency did you estimate when incorporating the final drive and first gear ratios? 85%?

Looking at the geometry of the rear I'd guess that the summed force isnt applied through a single component either onto the ear and beam. Would I be right in thinking the diff ear tears or do the spots pop. Or both?
Slow reply but the loads are soley generated by the torque through the driveshafts to the wheels. I assumed no losses at all in the calculations to get worst case. There is much discussion about what what fails first. Mostly its the spots welds but Randy Forbes has the most knowledge on this and he thinks either can fail first - I had a recent exchange with him on that very topic on bimmerforums. I have recently come to the realisation that there is a strong link between the failings of the boot floor and occurrances of driveshaft problems. I see an increasing number of posts with older high mileage cars suffering problems with the driveshaft intermediate bearing. Some have fixed this to find it fails soon after. On my car I found the boot floor had been pulled down about 5mm in the centre. Most cars will have some deformation in this area even if the welds are ok. You can easily check for this by putting a straight edge along the boot floor. When there is some permanent deformation it causes the rear of the differential to sit lower and the alignment of the differential to the engine centreline is lost. This will manifest as extra forces and/or vibration in the driveshaft and potential intermediate bearing or yoke failures. When repairing damage to the boot floor it is important the alignment is considered otherwise a 'fix' may leave a lurking problem in there with misalignment built into the rear diff mounting. An early post in this thread showed me fitting an offset bush in the rear diff mount in my car. I'm now thinking this was necessary to correct the movement in the boot floor, to get the diff and engine centreline inline. This always troubled me slightly since the S50 and LS3 were, on paper, sitting in similar positions.

Anyway moving on from that I have been planning a few upgrades to the car and have been accumulating parts for a while. Some of these are on hold while I sort out a rather annoying emissions problem. It has its forth Mot book this Friday so fingerts crossed! The mods are to sort the front wheels and steering. I am fitting a slightly wider front rim with new tyres, a (quick) z3 steering rack, negative camber plates and a new steering wheel. This is all aimed to improve the handling balance and steering feel. Well worth the £1k its cost I hope - eek!

First stage is fitting the new steering wheel. I have been encouraged by many positve comments on the Raid wheel so have been looking into getting one for a while. My plans to save some cash by buying secondhand have not ended up being that positive when all the costs are summed. I bought it knowing its needed reburbishing. All in its cost £400 but I had opportunity to have it covered in Alcantara with 'M' stitching. Its therefore made it a little different to the norm and I'm happy with that. Let me know what you think...

Image066 by deansie1712, on Flickr
Image070 by deansie1712, on Flickr

I had a little drive yesterday. The wheel feels great. Since I have not driven the car fast for a while I was more taken aback by the speed of the car :shock: Spinning wheels in 3rd again on the throttle. Such fun!

More on the remaining mods next time...
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Re: Z3M V8 Conversion

Post by whiteminks » Mon 06 Aug, 2012 23:05

Mmmmmmmm looking good! Is it Mike F who has a RAID steering wheel too? Have you worn your tyres out yet ? Looks great fun but I dread to think how much the tyres will cost to refresh????
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Re: Z3M V8 Conversion

Post by shantybeater » Tue 07 Aug, 2012 09:30

What offset/width changes are you making to the fronts? Will be very interested to hear what you think of the z3 rack, its been on my list for a while now...

Nice to meet you at silverstone by the way :) car looked great and made some lovely noises in front of me on the parade lap!
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Re: Z3M V8 Conversion

Post by Deano1712 » Tue 07 Aug, 2012 11:38

shantybeater wrote:What offset/width changes are you making to the fronts? Will be very interested to hear what you think of the z3 rack, its been on my list for a while now...

Nice to meet you at silverstone by the way :) car looked great and made some lovely noises in front of me on the parade lap!
It was good to meet you too. Your car looks great btw.
The fronts were originally 8.5x18et38 but fouled badly with the KWv3 springs and perch. I changed the inner shells to sort this which took the wheels to 8x18et32. I'm now fitting a 1/2" bigger outer lip so will be 8.5x18et25. I wasn't happy with the look of the front wheels - no dish at all. This was a result of needing so much brake clearance and the position of the split rim flange. The slightly larger lip should improve the look. There will be no more poke at the front since I am reducing camber by 1 degree.
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Re: Z3M V8 Conversion

Post by c_w » Tue 07 Aug, 2012 16:06

The "quicker" standard Z3 rack makes the car feel much more responsive IMO as does the smaller wheel.

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Re: Z3M V8 Conversion

Post by foler » Mon 17 Sep, 2012 16:51

which emission problems exactly you have? high co, no, lambda? what you are try to do to this days in fight with tune?

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Re: Z3M V8 Conversion

Post by Deano1712 » Mon 17 Sep, 2012 19:29

foler - it was high Co caused by lamba running at around 0.95. I think I had a small leak in the headers and I also did a mod to the timing. See thread here on HPT: http://www.hptuners.com/forum/showthread.php?t=39812 Its now passed ok but there were still problems at fast idle. The Cats I have are not great and dont stay hot enough to work at 3000rpm with no load. I have found the best way is to get a friendly tester :wink:

I have done a few mods recently and its getting close to the finished article now...

First job was adding a bit of negative camber:
Image097 (2) by deansie1712, on Flickr
I had a couple of adapter plates made to add camber and its now measuring +2.2 degrees. Perfect:

Image003 by deansie1712, on Flickr

I rebuilt the front wheels with a wider outer lip and fitted Michelin Ps2's to match the rear.
Image004 by deansie1712, on Flickr

The front wheels look a lot better now IMO:
Image014 by deansie1712, on Flickr

The car now has a standard z3 steering rack which has a faster ratio to the Z3 version (2.7 vs 3.2 turns I think). The net result with the camber, tyres, rack and steering wheel is excellent. The car is much better balanced, confidence inspiring and I'm very happy with the results. I'm now able to throw it into the corners and enjoy the power. The wider rear tyres have loads of grip and dont spin beyond first when warm.

I went with Aceman to a TVR meeting local to home and did 1/2 hour on a runway giving it the beans. A couple of videos here showing it reaching around 150 after a mile. Fun fun fun!!
http://www.youtube.com/watch?v=sqytBaGHRGE
http://www.youtube.com/watch?v=FiR0lyQLrPE
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Re: Z3M V8 Conversion

Post by resunoiz » Tue 18 Sep, 2012 09:06

NOT to be polemic, at first.
But a V8 with a so different conception doesn't pervets the nature of the ///M philosophy?
Not for the power itself, but weight balances, engine type (6 in line vs V8 ) seems to me so distant from a M car...

Surely is a very big experiment for a "monster car" ;)
Im' curious to know the drive feeling differences on a track with a majour upgrade like this :)

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Re: Z3M V8 Conversion

Post by c_w » Tue 18 Sep, 2012 10:55

V8s are used in the E39 M5 and now E90 M3 so it's not unknown for use in an M car. The V8 engine is slightly lighter I think, and 2 cylinders shorter so it sits relatively further back so handling in theory should be better than the straight 6 3.2 engine.

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Re: Z3M V8 Conversion

Post by resunoiz » Tue 18 Sep, 2012 11:04

c_w wrote:V8s are used in the E39 M5 and now E90 M3 so it's not unknown for use in an M car. The V8 engine is slightly lighter I think, and 2 cylinders shorter so it sits relatively further back so handling in theory should be better than the straight 6 3.2 engine.
and for the weight balances? more or less weight can be a "surplus", but in the general car setup? M5 e39 and M3 E9x are obviosly differently balanced, due to different shape, measures and so on.

It's only a doubt, I have to point on, and NOT a critic. I always figured out that a car is not only maximum speed and acceleration, but handling too. Is not a risk to compromise this (for me) crucial parameter altering wheights? Obviously, if in addiction to motor swap there aren't other tuning works :wink:

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Re: Z3M V8 Conversion

Post by Deano1712 » Tue 18 Sep, 2012 11:27

The car has just about every suspension mod you can do. As a drive I would say these changes are more significant to the feel of the car. The V8 gives plenty of torque and a nice sound. Clearly the intention with the conversion wasnt to keep it standard /M!

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Re: Z3M V8 Conversion

Post by resunoiz » Tue 18 Sep, 2012 11:31

Deano1712 wrote: Clearly the intention with the conversion wasnt to keep it standard /M!
obviously, is the primary premise :D
and think a great satisfaction for DIY enthusiast :)

you didn't notice something different in feel on the track with new balances?

luckycolourblue
Joined: Sat 11 Apr, 2009 17:39
Posts: 62

  M roadster S52
Location: Bristol

Re: Z3M V8 Conversion

Post by luckycolourblue » Tue 18 Sep, 2012 15:35

resunoiz wrote:
c_w wrote:V8s are used in the E39 M5 and now E90 M3 so it's not unknown for use in an M car. The V8 engine is slightly lighter I think, and 2 cylinders shorter so it sits relatively further back so handling in theory should be better than the straight 6 3.2 engine.
and for the weight balances? more or less weight can be a "surplus", but in the general car setup? M5 e39 and M3 E9x are obviosly differently balanced, due to different shape, measures and so on.

It's only a doubt, I have to point on, and NOT a critic. I always figured out that a car is not only maximum speed and acceleration, but handling too. Is not a risk to compromise this (for me) crucial parameter altering wheights? Obviously, if in addiction to motor swap there aren't other tuning works :wink:
Were on earth have you got the idea that a stock Z3 handles well from :roll: :lol:

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c_w
Joined: Thu 19 Aug, 2004 17:50
Posts: 4032

  M roadster S50

Re: Z3M V8 Conversion

Post by c_w » Thu 20 Sep, 2012 10:30

resunoiz wrote:
c_w wrote:V8s are used in the E39 M5 and now E90 M3 so it's not unknown for use in an M car. The V8 engine is slightly lighter I think, and 2 cylinders shorter so it sits relatively further back so handling in theory should be better than the straight 6 3.2 engine.
and for the weight balances? more or less weight can be a "surplus", but in the general car setup? M5 e39 and M3 E9x are obviosly differently balanced, due to different shape, measures and so on.

It's only a doubt, I have to point on, and NOT a critic. I always figured out that a car is not only maximum speed and acceleration, but handling too. Is not a risk to compromise this (for me) crucial parameter altering wheights? Obviously, if in addiction to motor swap there aren't other tuning works :wink:
If the engine it a touch lighter (or even the same weight) it will be better if it's sat further back in the engine bay. Subjectively speaking the non-Ms feel nimbler because all the other 6cyl engine are alloy so significantly lighter.

resunoiz
Joined: Tue 04 Sep, 2012 17:12
Posts: 162

  Z3 roadster 1.9

Re: Z3M V8 Conversion

Post by resunoiz » Thu 20 Sep, 2012 10:31

luckycolourblue wrote:
Were on earth have you got the idea that a stock Z3 handles well from :roll: :lol:
know stock suspension sucks ;)

BUT I'm wondering (is a curiosity, as said) if different whieights can afflict handling :)

I've seen is not the only conversion here, but I wonder it was amde a lot of times. And that doubt has always remained "unsolved" :)

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fok
Joined: Sun 10 May, 2009 23:44
Posts: 46

  M coupe S50
Location: Warwick

Re: Z3M V8 Conversion

Post by fok » Thu 20 Sep, 2012 20:29

resunoiz wrote:
luckycolourblue wrote:
Were on earth have you got the idea that a stock Z3 handles well from :roll: :lol:
know stock suspension sucks ;)

BUT I'm wondering (is a curiosity, as said) if different whieights can afflict handling :)

I've seen is not the only conversion here, but I wonder it was amde a lot of times. And that doubt has always remained "unsolved" :)
Weight distribution with a well fitted LS* is near 50/50 in an M Coupe, so theory would suggest better handling.....I have yet to be 100% happy with mine but that's down to being lazy with set up of KW's etc.

I think that a V8 conversion makes for a better road car as power delivery is well suited for street use but I think on long open tracks the S5* powered car regains some of the lost ground as it can be kept revving.

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Deano1712
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Joined: Sat 05 Aug, 2006 13:56
Posts: 1394

  M roadster S50
Location: Leeds

Re: Z3M V8 Conversion

Post by Deano1712 » Fri 23 Nov, 2012 20:03

Its that upgrade time of year again. The car is off the road till Spring so I have a few jobs planned to improve a few things. First job has been to re-route the wiring on top of the engine and across the bulkhead. Its looking tidier now and I have engine covers at last. I have ditched the old PS pump and opted for a standard GM fit with the pump of the nearside. I knackered the old pump fitting it and it was a failure waiting to happen.
Image030 (2) by deansie1712, on Flickr
The cooling system has been marginal since I did the conversion so the plan is to sort that out for good. I got a new radiator, all aluminium with a thicker core. It looks beefy and hopefully effective. The old radiator was completely trashed due to the weight of the cooling fan hanging off it. I need to mount the fan differently so thinking how best to do that.
Image035 by deansie1712, on Flickr
Next job is making new exhausts. The centre section is first. I had trouble getting the car through MOT this year because the old sports CATS were ineffective. I have bought an expensive compliant single 3" CAT and plan to plumb that into a new twin 3" centre section. I am also making a catless section to swap out if I ever get the urge for more noise and performance :wink:
Here are a few bits from the postman.
Image029 (3) by deansie1712, on Flickr
Image019 by deansie1712, on Flickr
The 4" stainless pipe is for a cold air inlet. I'm planning to change the inlet and route it down under the radiator to a front facing cold air inlet. Some of these mods will raise the power a bit and there is the option to raise the top end hp to 560 with a new cam. Thats not a defo yet I keep changing my mind. Catless with the cam I would most likely use the sound would be similar to this...what do you think? Should I do it? It doesnt sound very BMW!
http://www.youtube.com/watch?v=XEpELxRk_S4
Last edited by Deano1712 on Mon 24 Jul, 2017 23:00, edited 1 time in total.
Z3M with a few mods...and a little bit more power

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aceman
Joined: Sun 01 Jun, 2008 12:16
Posts: 1478

  M roadster S50
Location: Wakefield

Re: Z3M V8 Conversion

Post by aceman » Fri 23 Nov, 2012 21:21

Ooh nice shiny bits :D

That car sounds awesome but then I am a sucker for a raw V8. For me as it is a weekend car a sound like that I could put up with and would put a permanent grin on my face that would have to be surgically removed but it all depends how you feel Mark. I can understand your apprehension as it will probably drone a bit on a long run but would sound awesome on full chat.

Don't forget to let me know when you start having a go at the TIG welding.
Aceman

Arctic Silver '98 Z3M

Previously;
Bright RED '99 Z3 2.8

Rocking seats ? You need seat bushes click HERE

swamper
Joined: Thu 13 May, 2010 18:14
Posts: 1866

  M roadster S50
Location: Mossley

Re: Z3M V8 Conversion

Post by swamper » Fri 23 Nov, 2012 21:29

DO IT...! :shock:
the badness makes me do it...!

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