300° BMW Motorsport cam

[jireland2002]

Thanks Ken

This is great data.  Is it for the factory 300?

 

By the way- Ken knows but for some others - A cam measuring devise like a "cam doctor" which uses a flat tappet does not give accurate data for a single overhead cam that has rocker arms.  You need the make the measurements with the cam in the head and rockers and valves installed.

[TobyB]

I use the Horror Fright device-

 

a cheap dial indicator on the valve itself.

 

Ramps really are quite a thing on these engines.

 

t

 

[kbmb02]

10 hours ago, jireland2002 said:

Thanks Ken

This is great data.  Is it for the factory 300?

 

 

 

 

Those numbers aren’t the factory 300 or Alpina 300, Jeff - but I will get them, soon (those were a Schrick camshaft). -KB

[JohnP_02]

If I may side track this conversation a bit and ask a question of the experts? In layman's terms, would a factory 300 cam "fit" without any modifcations to a stock e21 head (2002 version)? 

 

Preference for a street car with a 292 vs a factory Motorsport 300 if using fairly higher comp pistons and DCOE's. 

 

TIA! John 

Edited August 7, 2020 by JohnP_02

[Jam3422]

The factory BMW 300 cam has larger journals, so all standard M10 heads require line boring to install this cam.  Finding a machinist that can still line bore a head may or may not be difficult, depending on your location.  No one is left in the Puget sound region that could do it, so I sent mine down to Terry Tinney.

 

I can't comment on the 300 vs 292, but the 300 in my car with an otherwise stock (though oversize pistons) 9:3.1 ti build still has decent lower rpm torque.  Solex phh sidedrafts with modified jetting.

 

 

[Jam3422]

I forgot to say, seat of the pants impression only, no data.  I'd love to get it on a dyno someday though.

[JohnP_02]

17 minutes ago, Jam3422 said:

the 300 in my car with an otherwise stock (though oversize pistons) 9:3.1 ti build still has decent lower rpm torque.  Solex phh sidedrafts with modified jetting.

 

That is great to know! That is basically the same set up I am planning on going with, 9:3.1 pistons, 40DCOE's and either the 300 or 292. Thanks! 

[Einspritz]

On 8/6/2020 at 10:51 AM, jireland2002 said:

By the way- Ken knows but for some others - A cam measuring devise like a "cam doctor" which uses a flat tappet does not give accurate data for a single overhead cam that has rocker arms.  You need the make the measurements with the cam in the head and rockers and valves installed.

 

Well, yes in a way, that is the most accurate, using measurements for each degree of crank/cam movement. But for comparison, where you don't want to bore out the head journals for the 300 Deg. cam to get those measurements (unless someone else has done it) , you can take the lobe measurements throughout the rotation, and then use the rocker ratio to calculate the final results at the valve. That said, it will be a little off since the tangential point of the rocker follower vs. the cam lobe will change that a little bit, but fine for comparative purposes.

 

In the S14 world, I have a device that bolts to the head and has two "dial" indicators that track the valve movements directly, so all you have to do is attach a degree wheel to the crank, turn said crank, and get direct measurements.

 

As far as fitment of a high lift cam, DCOEs, etc. I think that you may be leaving some performance on the table with 9.3:1 pistons, even with today's gas. I have 9.6:1 pistons in my Tii; stock cam, E12, everything else "stock", (OK not really) but use the J&S along with a Lambda sensor to monitor AFR in real time. Had I known of the J&S at the time, I would have gone to 10:1 CR, which would have had better performance with 100 Octane, but no detriment with pump gas.

 

When I worked at a BMW shop, we routinely installed 10:1 pistons, in systems that you propose, but gas was different then.

 

In changing the cam and increasing the compression to 10:1 (or even 9.3:1) it is really advisable to use a knock sensor system (J&S) that will take care of knock despite a more aggressive advance curve, compression, deficient gasoline,  etc.

 

Did I mention that gas is different today?

 

Digressing a bit, with the cam/valve measurements, along with the head chamber volume, cylinder volumes, the CR, etc. you can calculate the trapped compression ratio, the BMEP (brake mean effective pressure) to ascertain your comparative performance(s), and calculate the knock frequencies, primary, secondary, and tertiary.  You can also see how much the effects of valve overlap (or lack thereof) with respect to exhaust gas reversion has on your performance. Nifty for comparison purposes.

 

It is important to note that "plug-n-play" of each of the elements, pistons, cam, head, carbs, distributor, etc.doesn't always work harmoniously. This is a system of elements that should be designed to work together to achieve the best performance possible; otherwise one deficient element (from air box to primary pipe) in relation to the others will hinder all.

 

In any event, if you are going for the full Alpina reproduction, you may consider reshaping the combustion chamber in the head by machining a domed combustion chamber as some Alpina heads (and those with the 300 Deg. big journal cams)  to accommodate the higher pop-up pistons......that shape is similar to the 2002 Turbo, BTW.

 

Just something for your consideration. YMMV. Either way, enjoy the fruits of your labor, the engine will be fun.

 

 

[02Anders]

For what it's worth, I run a pair of 45mm DCOE's with my 300 degree BMW Motorsport cam.  Goes well...  ?

 

 

[BarrettN]

On 8/10/2020 at 12:46 PM, Einspritz said:

I have 9.6:1 pistons in my Tii; stock cam, E12, everything else "stock", (OK not really) but use the J&S along with a Lambda sensor to monitor AFR in real time. Had I known of the J&S at the time, I would have gone to 10:1 CR, which would have had better performance with 100 Octane, but no detriment with pump gas.

 

Down the road I may eventually try building a higher performance tii motor along the lines of what you've done - just wondering, did you need any modifications to your kugelfischer pump for what else that you've done? Do you know what sort of horsepower you're generating?

[markmac]

300 degree cams work well with Weber carbys and multiple butterfly fuel injection (Alpina or other).  BMW Tisa's and Alpina, GS, Schnitzer and others were doing it long, long ago.  It is well proven.  If you have standard tii injection, I will advise you - don't go there, they do not work well.  Many years ago I was running a tii with Alpina injection + 300 motorsport cam, took the Alpina gear off and put the standard tii stuff back on.  Nightmare.  It ran like stink at like 6000rpm, but would not idle (no surprise).  There is probably someone out there that could make it work but would take ALOT of work, pump re-do + many other.  Even Schrick 292's don't work particularly well, in my experience anything more than a 284 is trouble....$$$$$$$.

[Einspritz]

The Kugelfischer pump is calibrated "as stock", for the early '72 versions, which means that ALL the curves, P1,P2,P3,P4 are within specification. The pump is capable of handling more fuel than needed for stock, and as such, the curves can be moved richer / leaner over all the curves, by the user ("The Screw"). There are other adjustments that can be made by a competent re-builder as well.  1974 US engines, of course, had different fuel cones and thus curves for emissions purposes. That may or may not work with a 300 Deg. cam.

 

Your pump re-builder / calibrator may vary.

 

Regardless the tuning is NEVER plug-n'-play, so adjustments are necessary for your type of fuel, E12 head,cams, etc and should be taken in account when the pump is serviced. There is Math involved, so planning is key.

 

As far as my '72 spec Tii (with plastic runners built by Franz Fechner and Dave Cruz), I have no idea as to the Hp, but can say it was a wise choice to gain Hp over the 2 bbl. Weber and header / non-SMOG compliant engine done in the previous restoration. My goal was better performance and economy without  going wild, able to meet CA SMOG laws, so that choice met it in spades.

 

I also changed the differential ratio to the "Euro" 3.45:1 and the engine runs at 4000 rpm @ 80 Mph, the sweet spot in efficiency for any stock cammmed engine,  always returning better than 30 Mpg, so that worked for me with mostly highway driving. IIRC the carburetted engine never returned more than 25 MPG.

 

But I digress.

 

I have driven another Tii at the track that was "Alpina spec" with the cams, compression, slide throttle, etc. but the pump cone was not Alpina. What a hoot! ......and a whole different driving experience from a stock Tii and turbo. Very responsive when you accelerated and then came up on the cam.

 

So, to the discussion here, sure go for it, but with sufficient planning.

 

HTH

[markmac]

Like I said, that 300 in my tii ran like stink, but driving it less than 4000 rpm not so much (of a 'hoot').  I had heard long ago of some folks running these in tii's - none recently.  It would take a lot of time (and money) to set one up and I think regardless of what you did there would be issues.  Looking forward to getting this guy finished and running.......schnitzer race pump unrestricted with 7.5mm pistons.  It flows a lot of fuel.

[Brams]

On 8/8/2020 at 1:50 AM, JohnP_02 said:

If I may side track this conversation a bit and ask a question of the experts? In layman's terms, would a factory 300 cam "fit" without any modifcations to a stock e21 head (2002 version)? 

 

Preference for a street car with a 292 vs a factory Motorsport 300 if using fairly higher comp pistons and DCOE's. 

 

TIA! John 

 

Anyone know how the BMW Motorsport 300 cam compares to the 292 schrick as well? 

 

From everything that I've read, its closer to the stock camshaft profile than the 292 schrick but is named a higher duration due to being measured differently?

 

 Alpina got 160hp at the crank out of the 300 cam, with 10:1 compression, 46 mm inlet valves, 39 mm exhaust valves, new headers and 45 DCOE's. It looks like people get similar figures with the schrick 304, but with worse idle and a higher powerband? Anyone know how this works, or have information on the contrary? Otherwise it seems like the 300 cam is the obvious choice (except for the line boring of the head)!

 

[Oldtimerfahrer]

There are multiple other posts on this topic, one even includes some data as well...Seems that Schrick does measure differently.

The 300 degree cam is certainly not aggressive, even with 45's, higher compression and a ported head the driveability is quite ok and you can even get a decent idle if all else is good.

A.