MM Turbo camshafts and MM behive springs

[bar73k]

i bought a set of MM turbo camshafts and their valve springs.

once in i put the car on the dyno and we have not been able to push the motor past aprox 17psi because we seem to experience valve bounce where power dramiatically falls off after 17 psi and above ~5000 rpm and up

so i stripped down the motor and pulled one of the new valve springs out to get the new and old measured for valve seat pressure

New MM behive springs = 72 Pounds

Original BMW M42 springs = 92 Pounds

now im unsure of what to do

either reinstall the original springs which have seen 22~23psi, but not with this camshaft
or try and buy some new springs with a higher valve seat pressure

[rob_e30]

If the stock springs have a higher seat pressure I'm not sure why you would not put them back in?  Any high performance spring for an M/S50 motor should work.  Are you also running solid lifters?

[romkasponka]

Springs depends also from camshaft lift.

[Boyracer]

Yeah, stock springs limit cam lift to between 10 and 11 mm, after that it's coil bind time...

Just today I received dbilas performance springs. They allow lift of 13 mm before coil bind and they are 15% stiffer compared to stock spring.

You could adjust seat pressure by putting shims between springs and cylinder head. That will eat away some max lift but it increases seat and max lift pressure.

[bar73k]

i will defiantly put the standard springs back in if i don't go for a stiffer set of springs.

and im just using the standard hydraulic lifters

standard cam's are 252 Duration 10.2mm lift (intake and exhaust)

MM cam's are 258 Duration 11.4mm lift (intake)
                   258 Duration 11.2mm lift (exhaust)

interesting u mention the maximum lift the standard springs can cope with, i never thought of this, ill have to further investigate that

[nickmpower]

Im pretty sure they have lower seat pressure but higher lift pressure. So less valve float

[Boyracer]

standard cam's are 252 Duration 10.2mm lift (intake and exhaust)

Are you 100% sure of this? I measured stock cams myself and only had lift of around 9,2-9,4 mm which is in line with what I have read from sources :confused:

MM cam's are 258 Duration 11.4mm lift (intake)
                   258 Duration 11.2mm lift (exhaust)

I think that much lift is recipe for coil bind ie. serious problems with stock springs!

Here is info by Cat Cams:

http://www.catcams.be/datafiles/docs/springsetup13014xx1.htm

OEM springs lift at spring coil collision 10,8 mm

So your MM cams will not work with stock springs. My regrinds have max lift of 10,4 mm so I have clearace of whopping 0,4 mm... Even that is way too low, it should be around 1 mm atleast :eek:

[nicknikolovski]

Check out vacmotorsports.com, they got heaps of performance products and even ready built stage 1, 2 & 3 cylinder heads and valvetrains.

[bar73k]

Are you 100% sure of this? I measured stock cams myself and only had lift of around 9,2-9,4 mm which is in line with what I have read from sources :confused:



I think that much lift is recipe for coil bind ie. serious problems with stock springs!

Here is info by Cat Cams:

http://www.catcams.be/datafiles/docs/springsetup13014xx1.htm

OEM springs lift at spring coil collision 10,8 mm

So your MM cams will not work with stock springs. My regrinds have max lift of 10,4 mm so I have clearace of whopping 0,4 mm... Even that is way too low, it should be around 1 mm atleast :eek:

now im not a 100% sure because i read somewhere that std lift is around what you are saying 9.4mm

the MM camshaft details are straight from their wesite

i measured the lobe on the std cams and the MM cams and it is the same?? shouldnt it be bigger??

i also put the springs into a vice and the MM springs reach full compression about ~1.1mm before the std springs do

[Boyracer]

i measured the lobe on the std cams and the MM cams and it is the same?? shouldnt it be bigger??

i also put the springs into a vice and the MM springs reach full compression about ~1.1mm before the std springs do

Hmmmm... This is very curious. How did you measure the lobes?

Sounds like MM springs are not very good if they are softer than stock AND allow less lift before coil bind :eek:

But there are so many variables and ways to measure things that we need to make sure all those are done correctly.

[bklepp]

now im not a 100% sure because i read somewhere that std lift is around what you are saying 9.4mm

the MM camshaft details are straight from their wesite

i measured the lobe on the std cams and the MM cams and it is the same?? shouldnt it be bigger??

i also put the springs into a vice and the MM springs reach full compression about ~1.1mm before the std springs do

I got tree different numbers, 228/9mm, 242/9,7mm and 252/10.2mm
And I think all of them is correct, but taken from different M42 engines, the E30, E36, us or the european.
We need to clearify this issue

[nuvolarossa]

bar73K, I will send you a PM. Read it.

[bklepp]

Don't be so mysterious, share with the rest of us

[nuvolarossa]

it was only a mail address of a man who I think could help to solve that.
 
He will report if there will be some news, as I'm curious too.
 
Have patience and news will come.

[xxxJohnBoyxxx]

I'm the guy nuvolarossa is taking about. You can email me or call me at 305 742-8559.

I do not work for MM but do a lot of free testing for them. I'm currently testing the Hybusa's Drag Bike springs good for 15,000rpm in a M44 with a GT30/70 A/R turbo:D

I have had decent results with the Beehive springs at 25psi at 8,000rpm but this was a M44 so different springs then the M42

When you say "Turbo Cams" did you replace both cams? normally you would want a stock exhaust cam in there and only change the intake. Also what did you set the valve lift off seat on #4 when when it was in overlap TDC (Degreeing the cam)

John Smith
Florida (Profile not filled out yet)