Jump to content

roller rockers for M10


B-Merry
 Share

Recommended Posts

There is a small company in Australia whose proprietor designs and builds performance parts. He has done some interesting work for the M20, including what appears to be the first set of roller rockers (aka roller cams) for that engine. He is an M20 racer himself. Here is a link to his M20 product offering:

http://racehead.com.au/products-page/bmw/bmw-m20-roller-cam-conversion-kit/

The quality of his product appears to be very high. I have contacted him to enquire about his interest in developing a roller cam system for the M10. He indicated that he would be interested if he could obtain 4-5 preorders. For the M20 he offeres two standad configurations, for street and race usage, but for an additional fee you can specify your own criteria and his cam manufacturer will design a custom cam. He indicate to me that for the M10 the price would be approximately $2000 for the system.

There are a number of benefits to a roller rocker/cam system: lower power losses to friction, reduced wear to cam lobes, no more rocker pad wear issuse. But the biggest benefit is the ability to achieve more rapid lift and greater lift rate and maximum valve lift, with reduced valve overlap. For my pusposes, street use, it permits increased high end performance without incurring low rpm torque loss and issues with smooth idle, well beyond what is achievable with conventional cam designs.

What he actually does himself is design and manufacture the rocker, and select parts for the rest of the assembly. He buys the parts from high end suppliers, based on his design specs, including the cam designer/fabricator. I am hoping there is enough interest to get him to design the system and make it available to the M10 community.

If you're interested I encourage you to reply to this thread and reach out to Rama, the proprietor of racehead.com.au to express your interest.

I asked him about reliability/failures and he indicated that he has had no failures whatsoever, and that the system he has in his racecar shows no signs of wear after considerable instensive race usage.

Jim

BTW, there are a two lengthy threads that chronicle the development of his M20 roller cams:

http://www.e30tech.com/forum/showthread.php?t=108906

The link to the second thread is contained in the last post on this thread.

Edited by B-Merry
Link to comment
Share on other sites

Mintgrun,

I am familiar with this thread, but I don't think the rockers were actually ever offered as a product. Robert seemed to have advanced stage prototypes that looked very promising, but no updates for 15 months on progress. If 02Robert has, or soon will have, actual product that would be exciting too.

Jim

This topic came up in Sept 2012 and the rockers were offered in Dec 2013, for about the same $2k price tag.  

 

Here is that thread for comparison 

 

http://www.bmw2002faq.com/topic/133673-new-cnc-machined-roller-rockerarm-for-m10m30-by-dynotechse/page-4?hl=%2Broller+%2Brockers#entry975262

Link to comment
Share on other sites

Seems to me that you would need to really be pulling some serious RPM's with a high lift cam (BmW 324, AlpinA 320, Schrick 316/336) to warrant a rocker/roller type rocker arm ( 8v Race Motor), otherwise with a street motor you are probably in the 7-7500 range (maybe not, maybe you all are driving your cars up past 8k?).  Even with an AlpinA 300 cam and A4 fuel injection I don't know that I ever found myself north of 7500 rpm's (and not even there on a regular basis).  These guys have an interesting offering, appears to be a steel (?) rocker with needle roller bearing.  Don't know that I have ever seen one that looks like this (with the roller bearing on the shaft).

 

http://www.modul-motorsport.de/artikel.php?aid=223&katid=24

 

http://www.alpinabmw2002.com

Link to comment
Share on other sites

Seems to me that you would need to really be pulling some serious RPM's with a high lift cam (BmW 324, AlpinA 320, Schrick 316/336) to warrant a rocker/roller type rocker arm ( 8v Race Motor), otherwise with a street motor you are probably in the 7-7500 range (maybe not, maybe you all are driving your cars up past 8k?).  

 

http://www.alpinabmw2002.com

I'm driving a tii, and I've been told going to a 292 or 304 provides much improved power above about 3500 rpm, but low end torque is progressively compromised and achieving stable idle can be problematic. (It seems it is less problematic with carburetors, because I've seen posts from people here with carburetors who say they like the 292 or even 304 for street use.) So for me the appeal is to be able to get 292 or maybe even 304 type of performance with no compromise below 3500 rpm. Of course the issue of tuning the kugelfischer will be there to some extent, but I'm hoping to a lesser extent than the higher duration cams (292/304) of conventional design becuase the power curve is more linear (I believe). While you can presumably run the roller cam way up in RPM, that is not what is attracting me. Racers here on the forum may have other motivations.

Jim

Link to comment
Share on other sites

Seems to me that you would need to really be pulling some serious RPM's with a high lift cam (BmW 324, AlpinA 320, Schrick 316/336) to warrant a rocker/roller type rocker arm ( 8v Race Motor), otherwise with a street motor you are probably in the 7-7500 range (maybe not, maybe you all are driving your cars up past 8k?). Even with an AlpinA 300 cam and A4 fuel injection I don't know that I ever found myself north of 7500 rpm's (and not even there on a regular basis). These guys have an interesting offering, appears to be a steel (?) rocker with needle roller bearing. Don't know that I have ever seen one that looks like this (with the roller bearing on the shaft).

http://www.modul-motorsport.de/artikel.php?aid=223&katid=24

http://www.alpinabmw2002.com

Marc, take another look at the OP's link above. The cam follower is a bearing rather than a flat pad. Your link is to lifters with needle bearings on the rocker shaft. These appear to be very different solutions to different limitations.

These are quite common with performance builds of american v-8s based on what little I know...

http://www.summitracing.com/search/product-line/crane-ultra-pro-mechanical-roller-lifters

I like the idea but I can't say I'm in the market for something like this right now. Looks like a cool product to have out there when I do get to the engine build. Good luck to the OP in finding a few interested folks to get this started.

Edited by bento
Link to comment
Share on other sites

I'm driving a tii, and I've been told going to a 292 or 304 provides much improved power above about 3500 rpm, but low end torque is progressively compromised and achieving stable idle can be problematic. (It seems it is less problematic with carburetors, because I've seen posts from people here with carburetors who say they like the 292 or even 304 for street use.) So for me the appeal is to be able to get 292 or maybe even 304 type of performance with no compromise below 3500 rpm. Of course the issue of tuning the kugelfischer will be there to some extent, but I'm hoping to a lesser extent than the higher duration cams (292/304) of conventional design becuase the power curve is more linear (I believe). While you can presumably run the roller cam way up in RPM, that is not what is attracting me. Racers here on the forum may have other motivations.

Jim

 

The main issue you're facing has nothing to do with the valve train.  If you want to run a (perfectly suitable) 292 cam on a Tii you're changing/modifying the injection to make it happen without compromise.

 

And if you've heard that a 292 has a compromised lower end (with a decent carb) I'd say that person shouldn't really be giving advice, let alone working on a car.

 

In short, we're talking about a ($2K) fix when there isn't much of a problem, that's a tough sell (something I think Jim Rowe, Rama, Robert, and anyone whose design roller rockers would admit).  Unless the price dropped considerably like with the afore mentioned v8's (which wouldn't happen based off of low comparitive production volumes) this wouldn't really take off, even if it is really cool.

Edited by AceAndrew
Link to comment
Share on other sites

Andrew, no one has been tellling me that a 292 has compromised low end when run with a decent carburetor. I said that, from what I've read on the forum, "people here with carburetors who say they like the 292 or even 304 for street use."

According to Schrick's technical specs,

"If the vehicle is intended for normal street use, i.e. with a stable engine idle and the ability to pass an emissions test (idle to lower rpm range), it is important to consider a small valve lift at TDC. The table gives a guideline for valve lift at TDC.

[From Table] 2 Valve engines with solid lifters 2.3 mm

When these values are exceeded, the engine idle will become increasingly unstable and the torque delivery in the lower rpm range will be noticably weaker."

The valve lift at TDC for the Shcrick 292 and 304 are 2.6mm and 2.9mm, respectively, so they are in the region that Schrick cautions the reader about for street use. But they also, make a statement: "Camshafts with larger valve durations, and a resulting higher valve lift at TDC, should only be considered for racing applications, or when each cylinder has it`s own butterfly valve i.e. 2 twin-choke carburettors on a 4 cylinder engines."

But I am driving a tii, and for my car I believe a conventional cam design somewhere in the range of a Schrick 292 - 304 would compromise low end torque, (at least with the tii throttle). But based on Schrick's comment about "when each cylinder has it`s own butterfly valve i.e. 2 twin-choke carburettors on a 4 cylinder engines" makes me wonder whether the loss of torque would be mitigated with an Alpina A4 type of ITB setup. I would be interested to hear people's experience comparing the performance using the stock tii throttle verses ITBs using higher duration cams. Is the loss of torque mitigated with the ITBs? Is it any easier to tune the Kugelfischer with ITBs and the longer duration cams, than with these same cams and the stock throttle?

I have heard that tuning the Kugelfischer with the higher duration cams on a tii is an issue. I've also read on this forum that the Kugelfischer for the A4 used a stock cone, but was just tuned differently. I would be interested to learn more about this.

As far as the roller cams are concerned, it seems like they would avoid the idle and loss of torque, (for engine configurations where these problems arise), since the valve overlap can be reduced while maintaining the advantages of longer duration and higher lift. If this is the case, then perhaps tuning the Kugelfischer would be easier, since the engine is not losing torque at low RPM and gaining power at high RPM. Maybe, maybe not.

I'm definitely not expecting sales to take off, but it would be nice if this became a real product. It might be of interest to racers...

Edited by B-Merry
Link to comment
Share on other sites

 

 

 Roller cams offer superior valve opening speeds and allow a more aggressive profile with higher lift

This, really.  You can get the valve open faster with a roller than a slider (durably)

 

You can also run a higher pressure spring, which means you can run a steeper closing profile.  To a limit, of course.

 

So the cam design can be more 'aggressive' and improve flow without excessive overlap- which is good, especially on a street motor.

 

A roller TIP will just reduce wear on the valve stems.  And save you $50- 100 on your next engine rebuild, at best...

 

t

Link to comment
Share on other sites

Toby said it exactly. There is nothing inherently wrong with the standard rockers. In addition to the much steeper lobe profile, reduced wear and less friction are major benefits. At higher RPM's, there is less chance of an odd harmonic causing a floating valve, so they are a bit safer at higher rpms. 

 

Really though... Roller cams and all these hoo-dads are just trying to improve a bad situation... Valves impede flow, and if we really want an engine that is tuned to its maximum capability, the valves need to be removed entirely. :)

Link to comment
Share on other sites

  • 4 weeks later...

I'm just a stupid guy - I don't get it?  Are there so many folks out there pulling so many RPM's in there SOHC M10 motors that standard rockers are breaking right and left?  I guess if you want the "boots and suspenders" approach to your valve train 'cause your winding that succa up to 9k rpm's', or if your racing in GT3 or some other European race where "modifications are free"......A mod like this would not be allowed by any of the Vintage groups here in the states as it is beyond period.  That said, I am interested to see the final outcome .....

 

www.alpinabmw2002.com

Edited by markmac
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

  • Upcoming Events

×
×
  • Create New...