2 to 1 exhaust

Discussion in 'Airheads' started by Sabre170, Feb 18, 2013.

  1. Edelweiss-Motorsport

    Edelweiss-Motorsport Been here awhile

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    Sunday lunchtime sitting in front of the fire post,

    RecycledRS - yes here you bring up one of the burning spots, as I was writing before: the clearance is one thing, shape and form makes the next difference.

    In general:

    1. There are calculation basics that i found to be used in full out race engines to define the squish area in relation to the bore.

    2. Yes I use both, I machine the outer diameter area parallel and then open it in different angles depending on the complete setup, sometimes on bores up to 94 mm I keep it parallel all over.

    3. If you are not a friend of the last detail go with all done parallel instead of risking to use the wrong angle....since this blows it all.

    4. Machining the end of the squish too round and smooth will also blow the magic by a huge factor...better keep it edged, whatever they tell you in any book.

    5. To take care of what is happening please hold in mind that you have to overcompensate the squish work - so go get the effect by the minimum possible losses.

    6. Squish work is living from and at below 1,5 mm...

    7. To make it tighter and tighter will not be of direct linear effect - this is the next step where you see if someone knows what he is doing or not. On a high or even just good performing engine the squish must be a part of the concept and / or corresponding to all what you do. How far are you willing to go ? When will it be ok for you ? Or are you looking for perfection anyhow ? Answer this before you start doing it yourself ! Below 0,75 mm you will find no effects that are worth being discussed in any case.....this is just valid for our 2V BMW engine !

    Here are some more questions / comments to give you the most possible complete picture -

    To give a useful advice please tell me:

    What bore diameter below what exact cylinderhead are you using ?

    What is the piston to cylinder clearance ? Steel liner or alu Nikasilcylinders ?

    What camshaft will be used ?

    What conrod length are you about to use ?

    The last question is underestimated or even missunderstood most times.

    It comes from the fact that the kinematic effects of the conrods are misinterpreted very often. If you try to calculate what is the outcome of a longer conrod in relation to the latheral forces from piston to cylinder you will find out that it is in our case not worth talking about it. All started for me when I was building the first complete self engineered engine using the 97 mm Mahle cylinders that where available and common that times. It was my intention to fabricate a very light and small two ring piston that was leading me to a conrod that has to be 13mm longer then the std. one. So in 1993 I ordered 148 mm conrods from Carrillo - and this was against all trends and all what the well known tuners that times, even the woks bmw people where doing. They all reduced the conrod length to 125 mm using very light titanium conrods....

    Ok on the dyno we could not believe the effect - it was the first ever build two valve bmw engine pulling veritable and often measured by different magazines 100 plus HP. This is not questioning what Udo Gietl did in the 70's but as the time went by I got all engines from all mentionable tuners on my own dyno and I can tell you by 100% safety the strongest one was the engine of my first ever race engine customer European Champion Mr. Julius Ilmberger who delivered an engine to me prepared from the works tuning guru Mr. Otto Lantenhammer in Munich. After I was overtaking him with my bike on a straight at Dahlemer Binz which was a famous airfield race that times he came to me saying: whoever was building the engine in your bike will build engines for me from now on.

    This Lantenhammer engine has already a 100 mm bore and an output of 92 HP - all others where below that figure...!

    Ok we did longer conrods, other pistons, new heads with std. port angle instead of the straight ones an other cam and generated close to 110 HP with 45 mm
    Bing slide carbs. Julius Ilmberger and his team mate where then classic bears champions using Edelweiss Motorsport engines and parts.

    The longer conrod has a great influence because it makes the piston stay longer at TDC and when it is there it is part of the porting.

    So as a side hint: try to understand the system and make your piston dome flowing....

    However the longer conrod is also supporting the exhaust side and was at one time resulting me to develop and use asymmetrical cams.

    Try to think around the next corner and you will see quite clear that conrod length has to fit the squish.

    Carl - thanks for the tip !!! now try to find Sade Adu on youtube singing charish the day on her lovers life tour 2001...what grace and beauty combined with a package of coolness and sex, wow this is breathtaking !

    Alternative from Sweden and a total different direction - band junip - song: line of fire

    Keep on rocking in a free world....yours,

    Dirk
  2. RGregor

    RGregor Been here awhile

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    Hallo Dirk,

    the name's Udo Gietl.
    I have a loose email contact to him and although he represents the 70ies era he has a lot to tell.
    At the moment he's restoring his old R90S street bike, giving it a roller cam setup.

    It's often heard that the old power figures are exaggerated. I tend to believe that.
    On the other side in '76 the B&S bikes were trapped at over 143 mph or 234 km/h top speed.
    The later bike at more than 150mph.
    With near stock R90S aerodynamics.
    I'd say it takes some serious power to get there?

    Greetings to the fire post

    Rudi
  3. Edelweiss-Motorsport

    Edelweiss-Motorsport Been here awhile

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    Hi Rudi,

    Yes you are right - I never had the chance to dyno Udo's engines and this is the reason why mention him explicit at this point.

    The bikes where fast and yes you are right again power numbers today are harder to get since correction factors and norms where making them much more conservative.

    When I started I was trying to get all available information about the B+S bikes as well as of the very very fast Wolfgang Schnepf engine - which I consider the strongest at that times with 1000ccm during the wunderful bot years.

    Wolfgang was a young innovative BMW Ingenieur that times and later worked for Porsche in Weissach. We met each other at a race in Oschersleben and stayed in contact since I work for Porsche on a loose basis as an instructor since then.

    Tell Udo and his sister Helmut that he should not go for the roller cam - I did all this and still have all parts on stock....but for a lot of reasons it is not the way to
    the holy gral. Flat tapped cams are easier to get modern profiles on.

    If he is trying to get nascar technology, like some guzzi dudes did, inside the flat twin tell him it means 17 mm valve lift or even more which will not fit into the rocker geometry at all, beside this you calculate the lift in approx 28% of the valve diameter...so this is also a question to be answered.

    So better using a current racecam, mushroom lifters if necessary....etc.

    If he wants to take the next step - our all new developed billet heads are around the corner.....not thinking this is right for a vintage R 90 S.

    Best regards to Udo and Helmut !

    Dirk
  4. RGregor

    RGregor Been here awhile

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    Hi Dirk,

    Udo's restoring his bike to be like it was in the 70ies, not developing it any further.

    Greetings, Rudi

    PS: there's a slight chance that I'll ride to the Classic TT in August. I might drop in for a coffee then. Any holiday planned then?
  5. supershaft

    supershaft because I can

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    Easy Less, you might ask more questions or contradict Dirks opinions if you knew more and had some experience of your own with topics of this discussion. I was basically asking just one question but I never really got an answer so I am giving up on that issue. I know a lot of inmates that appreciate my comments on 336's that counter a lot of the cams negative legacy. Some of it I agree with but I think some of it's supposedly negative attributes are actually good things. There is no need to ask Dirk about things I have been advocating for a long time here. Late model small port heads and long rods are two of the bigger things IMO.
  6. pommie john

    pommie john Long timer

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    Dirk

    I found the pushrods on your site but they are not in the online shop.
    What is the price? The seem to come without the end fitted. Is this so the customer makes them the correct length for their motor or do they come assembled?
    Mine need to be shorter than stock due to the piston/conrod combination I have.
  7. supershaft

    supershaft because I can

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    That makes two of us. I am in the market right now for one OR two sets. Most American tuners are using 4130 pushrods. Some are using 4140 and a few other alloys but I am not running near the spring pressures they are. BUT we have longer pushrods than most of those engines. My 4130 rods did lower my valve float rpm a little I believe although I am not positive about that yet. You do have to be very cautious about those experiments. I have seen many an airhead bend a valve for them floating. I did over rev the crap out of it a month or so ago and nothing touched. Most all of the American race car guys are running 4130 pushrods two to three times heavier than they were ten or so years ago for more rigidity and power with very little effect on float rpm. My 4130 rods are twice as heavy as BMW steel rods and three times as heavy as their aluminum rods but, just as they said on the phone, it barely effected my float rpm. Right now I am guessing it's 300rpm lower but I had already raised it around 500rpm with titanium spring retainers.

    By the way, BMW steel pushrods DO flex too. Not as much as their aluminum ones but they do. I looked at a pile of them a friend has and, sure enough, not all of them like with their aluminum rods but some of them showed the exact same tell tale signs of flexing in the exact same places as BMW's aluminum rods. My rod manufacturer says they couldn't get aluminum rods to not flex but, like I said earlier, they are running a lot more spring pressure.
  8. Carl

    Carl ,,,

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    Hi Dirk,

    OK, first about sound. That is the sound of music and not BMW Twins...

    Yes, Jaki Liebezeit does some stellar percussion. It is such a shame that Can, and others from your area, never toured much (or at all) here in the states. I'm familiar w/ Kraftwerk's background and their home base location being close to you. I saw them live in 1981. They had their Kling Klang studio system w/ them and they blew out the speakers (might have been house speakers). It would have been nice to hear Herr Schneider doing some of the electric guitar material from their earlier days, but that was not to happen. It was still lots of fun. I read where they do not like to travel because it is a waste of time. Now that so much can be done electronically while on the move one would think that is not the case.

    So you tend to like the Zappster. Being from the states I was able to attend plenty of his live shows. Interesting enough the Grandmothers of Invention had a tour in the states last year. I caught one of their shows in a very nice theater. To me, they seemed to jam way more pleasing and intense than when they ever did with Frankie!

    I'll give a spin to your latest music suggestions. I've heard of them and now need to venture further down the road.

    So, now back to the BMW Twins sounds...

    I figured so that you were CNC'ing the ports for precise duplication. I'm well versed on the one man band show and only two hands. :D Note: There was a request for pics of your end result. That's not from me. I respect when someone does their homework.

    You commented about also CNC'ing seats/heads. Such as guides? Valves? Are you saying that is only way how you are able to get top performance or peak power from your engines? I get to play in some form or another w/ machinery from 50 years and older to state of the art machining centers on a just about a daily basis. There's plenty of not so good product that is done on high end equipment that primo golden oldy machines can do, and vice versa. I'm just curious if CNC has been the way you able to squeeze to the nth degree that extra power from head reconditioning. Or is it the 'one man two hands theory' need for CNC?

    Nice to have you around. I'm sure there are many others that appreciate your technical knowledge w/out a 'my way or no way' approach.

    Carl

    p.s. Please place a cloth underneath the rod that is resting on the engine case cylinder bore that is on your website. :wink:
  9. bmwrench

    bmwrench Long timer

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    I, too am enjoying Dirk's posts. I couln't find a pic of the pushrods on the website. May we have some specs on the cams?

    Am I the only one who has trouble navigating suppliers' websites-including my own?
  10. pommie john

    pommie john Long timer

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  11. chasbmw

    chasbmw Long timer

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    I also find websites from Germany especially bad for online shopping. Even when they have an English translation.

    follow the link to SHOP within the text on the home page. piccies of pushrods under valve gear I think. They are setup so you cut to size, which is obviously aimed at people who know what they are doing.

    I like the way they approach fitting their version of the 1070 kit, the price includes fitting the kit to your engine including machining the squish band and a test of the engine!

    A bit difficult to arrange if you are an ocean away.

    The Dyno figures are not outlandish as they have been adjusted from RWHP to crankshaft, it would be interesting to know what the adjustment figure should be, but at 20% this brings the 90HP down to 72.
  12. Les_Garten

    Les_Garten Been here awhile

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    Hey wrench, what's your website?

    Getting Cam specs, sheesh, they just don't give good information. The worst IMO being MI.
  13. bmwrench

    bmwrench Long timer

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    thenickwackettgarage.com
  14. supershaft

    supershaft because I can

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  15. supershaft

    supershaft because I can

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    Be careful asking for cam specs! That got me two weeks of grief a while back in a cam thread.
  16. pommie john

    pommie john Long timer

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    OK, I switched to a more modern computer and I can link to the pushrods.
    How much for a set Dirk?

    [​IMG]
  17. supershaft

    supershaft because I can

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    What alloy too? Why use the long, stock style tips? Some might suggest that they are part of the problem.
  18. ontic

    ontic

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    We've swapped a lot of emails Dirk, so I was already very grateful for your time and advice, but let me join the others and say a big thanks for sharing your knowledge and experience here:clap. This has been great reading.
    Cheers,
    Hans.
    (P.S. I'll be in touch again by email once I am back in Australia to continue where we left off!)
  19. Edelweiss-Motorsport

    Edelweiss-Motorsport Been here awhile

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    Dear all,

    There is a lot of work in front of us currently so once in a while it will take a moment to answer.

    Hans - my pleasure !

    Pommie John - Yes this picture is very old and the push rods you can see there are not what we use today. That time we where thinking it is a good idea to use the std. top ends because they where small in diameter and so generating space for our ratio rockers. Then we found out they break when the rods get stiff and so we turned away from this version. I talked to my webmaster this morning, he will put the new version including a current picture into the shop today or latest tomorrow.

    The version you will see there is used for + fife years now and was build into approx 50 engines - they work to perfection and never fail. We can deliver them in over length with the steel ends loose or in accordance to your specs incl. the steel ends pressed in. We will not charge anything extra for this work.

    Chasbmw - yes it is far away but since we live in the age of fed ex and ups people from around the world, even Japan, send us their heads and we prepare the the custom configured BBK piston, cylinder, conrod, cam and head gasket set for them including a squish band that works....

    The cam that is included will also be the right one - very often our asymmetrical EM2V1 but this is not a one size fits all package it is tuned to what our customers are doing: enduro, street, sport or even race.

    For that reason we also offer a very light weight two ring version that is generating some more corner clearance.

    The cam will always fir to the exhaust that you are about to use.

    Carl - yes cnc was the only way to generate that top level performance in a row. When doing ports and seats by hand you can not make one as good as the other. This was getting more and more transparent when the air upwards is getting more and more thin. When building engines in the 120 HP level all must be right. So when I was seeing the best ever numbers on my dyno - it is our blue race bike - I got this heads digitalized and then calculated into the cnc machining programm. In the meantime I do the same with all Porsche heads.

    There was my Edelweiss Motorsport HP2 Sport in several magazines pulling + 150HP and rated as the strongest n.a. 4V boxer BMW on this planet, this one is also cnc ported by BMW, maybe someone knows that they are doing the same.

    Working from my iPad there is no pictures available - but I will ask an employee to put some pictures of the cnc 2 V porting in here.

    Bill - I would be happy to be helpful in any way !

    Les Garten - please let me know what are the cam profiles that you want to be discussed ? If there is any experience on my side I will share all information with you !

    Best reg.

    Dirk
  20. Les_Garten

    Les_Garten Been here awhile

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    Hi Dirk,
    Thanx for dropping in and letting us pick your brain! We have some talented people here, but a lot are like myself, amateurs, not pro wrenches, or designers. So this is a treat!

    I'm interested in the Sport-Street type CAMs that most would be interested in, and how they differ in their character.

    These would be the various 320 varaints, the 324(which I have in a box), and the other sport street offerings by Edelweiss and MI.

    The other observance that a lot of folks would like answered is this:

    If I buy a CAM from Web or Isky, or others, I get complete specs with the CAM and all the check points are elucidated and mapped out for me. Why is this not the operating procedure for Beemer Cam grinders?

    Thanx for your contributions here!