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flyhilandsoft
Post subject: BMW V12 horsepower????  PostPosted: Oct 03, 2007 - 10:55 PM
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What kind of horsepower can I expect out of my BMW 850CI motor with no radical modifications. I want to install custom headers and maybe chip it. I have seen many computer chips for sale that will supposedly add around 30 to 35 horsepower. Is there any truth to this. I was hoping to get upwards of 350 hp with just these two options. While we are on the subject will porting and pollishing the heads do much for me on this engine?


Thanks

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RJNOffline
Post subject: RE: BMW V12 horsepower????  PostPosted: Oct 04, 2007 - 12:28 AM
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The big flaw in the M70 is twofold....the exhaust ports are crap (flow numbers truly suck) and the compression ratio is 8.8 to 1....very very low.

In order to build real power the old rule if thumb is about two HP for every cfm of flow(intake...and exhaust should flow 70 percent of intake)...up to a point.
Your goal of 350 hp is very realistic.... but a motor like this should be in the 500hp range with great heads and better compression plus cam timing.....
 
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AdrianBurtonOffline
Post subject: RE: BMW V12 horsepower????  PostPosted: Oct 04, 2007 - 05:26 PM
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The nice thing about the low compression is that you can boost it and not worry about detonation. Ofcourse you can always do the std hot rod things (stroke & bore) down the road if you want. That is until iamalittlepepper finishes with the heads that he is/was working on, then 100hp/liter should be easily available.

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flyhilandsoft
Post subject: RE: BMW V12 horsepower????  PostPosted: Oct 04, 2007 - 10:05 PM
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I suppose a couple turbos would do the trick since the compression is low. What turbos do they use on the DINAN 850 version? I would imagine this would get quite $$$$$$$$$. I was under the impression the boring this block was basically impossible because of the sleeves????? Am I wrong on that?

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AdrianBurtonOffline
Post subject: RE: BMW V12 horsepower????  PostPosted: Oct 05, 2007 - 05:41 AM
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It doesnt have sleeves, the cyl bores are coated with either alusil or nikasil, I cant remember which. You can bore the block and add sleeves. That is how you get an engine over 6L, it also will allow for using a std set of rings.

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flyhilandsoft
Post subject: RE: BMW V12 horsepower????  PostPosted: Oct 05, 2007 - 07:40 AM
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I have not done any engine work yet. I was told that the engine was a throw away engine if it had cylinder damage. This is interesting stuff. Where would you go about getting the sleeves for the larger bore?

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andyOffline
Post subject: RE: BMW V12 horsepower????  PostPosted: Oct 05, 2007 - 09:38 AM
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Turbocharging isn't expensive...... the biggest cost I have incurred if for the Motec ECU I am using.

You can use a pair of relativelly cheap T3's (or a Jap car alternative) add an intercooler and some injectors and away you go 500bhp and 600ft lb with no engine mods at all not even porting or cams.

I actually know of a guy who has done it to his 850 so will have a base map and turbo headers if you can convince him to sell a copy.... his completely std car with T3's did 444bhp and 540ftlb at the wheels on the dyno.

Of cause the hidden cost is that you have to upgrade every other part of the car to cope with this sort of torque and that is the really expensive part.
 
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RJNOffline
Post subject: RE: BMW V12 horsepower????  PostPosted: Oct 05, 2007 - 04:03 PM
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First of all let me say that yes you can bore the block and add sleeves...but its not like painting a house boys.... you need to heat the block in an oven and freeze the sleeves in nitrogen then quickly insert 12 of them in the block...al without any distortion... can i tell you from experience...sleeving a block leads to cracks about 50 % of the time.

And while it IS a low compression motor, its not a turbo motor... the valves are not designing for the kind of heat and pressure you will see to raise that. Again "throwing on " a set of turbos is not as easy as that...not if you want a reliable engine that lives for more than a year. I have seen Sti Subaru's with blown rings all over the place just based on cranking the pressure with chips...they dont build motors with more cost in them , than for what they were designed to do.
Frankly, i think what most here want out of their V12 is the sound and a reasonable amount of power. Considering that the M70 is pretty much a truck motor, a smart investment would be getting a full rebuild, new high compression pistons, stainless valves and bumpy cam from Schrick (although they dont offer much in the way of racy cams) and spend your nights with a grinder and a self made flow bench working on those exhaust ports . You may get 4 to 425 REAL hp out of it and it will sound the business. What will all this cost you? a heck of a lot. But then the twin turbo set up dont right is not cheap. Bolting on a turbo without adequate prep of the engine internals leads to big clouds of blue and white smoke . Un less of course you never drive it hard and are never in the boost. Everybody knows somebody who did it and they make XXX power.... but then i also see a lot of turbo guys at the dragstrip running 16 sec ETs....if you know what i mean...
Having said all that... i do like the M70 and i do own one.... i own it cause its cheap and a v12.... if price didnt matter id get a MB 12 for obvious reasons.
I think we all could get that DOHC system to work and pare down the costs overtime and be much happier with that approach in the end. But hey, individuality is what this hobby is all about so...do it your way ..
 
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flyhilandsoft
Post subject: RE: BMW V12 horsepower????  PostPosted: Oct 05, 2007 - 07:41 PM
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I really wanted to keep this engine reliable simply because of the labor involved in removing it for repairs. As all of you are aware it is not like pulling a SBC out of an old Chevelle. I want to install it and leave it there. I am hoping for moderate gains in horsepower. I like the idea of doing a little something internally like the cams with stainless valves and high compression pistons. I would love around 400 hp, and would be extremely happy with that. I havent had much luck in finding the performence parts of this nature. Is this BMW only or are there other parts suppliers for these specific items. I would like high lift cams from the 850CSI but like everything else they are very expensive, but who said it was going to be cheap.

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cribbjOffline
Post subject: Re: RE: BMW V12 horsepower????  PostPosted: Oct 05, 2007 - 08:52 PM
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flyhilandsoft wrote:
I have not done any engine work yet. I was told that the engine was a throw away engine if it had cylinder damage. This is interesting stuff. Where would you go about getting the sleeves for the larger bore?


The builder of my motor, Henry Lawrence in North Carolina does 6.0 litre linered conversions, and it's purported that Jay Esterer up in Canada is also building 6.0l linered blocks.

If you have really deep pockets, you could also go to Korman: http://www.kormanfastbmw.com/V12.htm

My motor will be a similar spec to Korman's Stage 3, less the custom rods, but with higher compression, and including the ITB's.

If you have any thoughts about getting this block sleeved yourself, be forewarned, it's not as easy as buying a set of SBC sleeves from Jegs or Summit and bringing everything over to Bubba's BBQ and Engine Building for fitting. You need to find a high end machine shop that has a boring machine that can handle these Alusil coated cylinders, and those shops aren't on every street corner. Even harder to find are shops that have the equipment and actually have experience boring & sleeving this motor. We're in a very small niche market with these V12's; it's not at all like getting a SBC built.

IMO, it's far safer just to buy a finished 6.0l short block, long block, or a finished motor from one of the sources above. They're all well known and have reputations to protect....
 
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flyhilandsoft
Post subject: RE: Re: RE: BMW V12 horsepower????  PostPosted: Oct 05, 2007 - 09:32 PM
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I think this is above and beyond what I really want to do. I dont need that much HP to drive to Sonic. Sure it would be nice but that is why I am building a replica to keep the cost at my level. I thought the subject was interesting that it could be accomplished though. I think this is way out of my league.

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AdrianBurtonOffline
Post subject: RE: Re: RE: BMW V12 horsepower????  PostPosted: Oct 05, 2007 - 10:44 PM
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One of the things that make the BMW so attractive is the fact that the block is way overbuilt. The real limiting factor is the heads. If they flowed better you would be looking at a real 500hp. Besides what other block can you push teh pistons out of the top of the block without a ridge reamer?????

To answer your question John, the reason that the engine has been deemed disposable is for exactly the reasons listed above, because MOST shops cant handle the job, not that it cant be done

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flyhilandsoft
Post subject:   PostPosted: Oct 05, 2007 - 11:55 PM
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Thanks for all the replies. I have so much work ahead of me. I originally wanted the engine just for the sound as well as the look, however more and more I am thinking of trying to get more power. It is very appealing to me but cost is always an issue. There is so much to weigh here but dont want to get to side tracked. I sure like the ideas but some of these options are going to get pricey. I need a raise!

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cribbjOffline
Post subject:   PostPosted: Oct 06, 2007 - 05:28 AM
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One of the reasons this engine costs so much to modify is that it's simply 12 cylinders instead of 8, so a set of pistons, or rods, or valves, etc. are going to be 12/8 = 1.5 times more costly than for a V8, plus there's the "BMW" factor. Camshafts are expensive because it's such a small market, and so few suppliers (1 - Schrick). (BTW Andy, if you're reading this, Henry says his roller cams and valve train are good to 7500, but he recommends new longer rods if you're going much over 7K)

The absolute cheapest power you can make is with a SBC, but everybody and their dog has one, which is a factor in why the people in this subforum are building V12's. That and of course the primary reasons are the love of the motor and its sound.
 
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AdrianBurtonOffline
Post subject:   PostPosted: Oct 06, 2007 - 06:49 AM
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EXACTLY!!!!!

Has anyone contacted any other companies about building a set of cams?

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