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Go Back   E46Fanatics > Tuning & Tech > Driveline, Engine & DME Tuning

Driveline, Engine & DME Tuning
Talk about driveline improvements, NA tuning and DME tuning your E46 BMW here. This includes diffs, intakes, exhausts, chips, software and OBD tuning.

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Old 07-18-2015, 01:09 AM   #1
bayern_munchen
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M54B28 using long rods

Here is what I am after: an M54B28 block using the longest connecting rods possible to improve the Connecting rod ratio and lower piston speeds over traditional setup of 135mm rods and 2.8l pistons.


M54 allow block, 211mm deck height.

M52B28 Crankshaft 84mm
M50B25 connecting rods 140mm
M54B25 Pistons, 27.75mm Compression height




So, on paper it looks like this:


84/2 =42 + 140 + 27.75 = 209.75




The M54B25 block using the 75mm crankshaft, 144mm connecting rod and, 27.75 CH pistons come to 209.25mm.




So, if I went w/ the 84 crank route with the long 140mm rods then, the M54B25 piston CH would change by 0.5mm. What do you think the compression ratio would yield with something like this? I'd say, it would go up by a full point..? 11.2:1
Do you think, there would be issues with piston\valve contact because of the additional 0.5mm in Compression height?
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Old 07-18-2015, 01:36 AM   #2
daniel_f.
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Instead of messing around with hardware for several months without knowing if that Frankenengine will run, give it some boost
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Old 07-18-2015, 02:01 AM   #3
bayern_munchen
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Quote:
Originally Posted by daniel_f. View Post
Instead of messing around with hardware for several months without knowing if that Frankenengine will run, give it some boost
nah, man...! I hear ya about the boost but, I am "up to something" on the NA side lol!
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Old 07-18-2015, 02:28 AM   #4
daniel_f.
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Thats fine unless you trying to build something thats not worth the hassle.

I hear you wanna use longer rods to reduce friction etc... Have you ever taken a look at asien high revving engines? They have bore/stroke ratios and conrod/stroke ratios that actually shouldnīt even work and they revv like hell and produce power and torque without taking care about those "magical" numbers.

If you wanna build it to say you build it, then thats fine. If you wanna build it to get power gains, donīt be a fool

You want N/A?

-> !!!
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Old 07-18-2015, 01:42 PM   #5
bayern_munchen
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Quote:
Originally Posted by daniel_f. View Post
Thats fine unless you trying to build something thats not worth the hassle.

I hear you wanna use longer rods to reduce friction etc... Have you ever taken a look at asien high revving engines? They have bore/stroke ratios and conrod/stroke ratios that actually shouldnīt even work and they revv like hell and produce power and torque without taking care about those "magical" numbers.

If you wanna build it to say you build it, then thats fine. If you wanna build it to get power gains, donīt be a fool

You want N/A?

-> !!!
You are probably referring to Honda's K20/K24 platform. Hey, you brought up HONDA and, not I...

I actually happen to have a fair amount of experience with the K24 block. With it's 87mm bore and 99mm (!) stroke, the 2.4l K24 will rev 8000 rpm with factory internals and close to 9000 with aftermarket lightweight rods. This, btw in a street-tune configuration. At 8500rpm, piston speeds will be over 8000fps. These motors make power all the way to red-line or about 8200-8500 rpm with a fairly flat torque curve from 2500 to 5000rpm. Speaking of pistons, a typical 'street tune' setup consist of 12.5:1 compression ratio running US pump gas 91 octane. I know, in Germany and central EU, 91 octane is used for cleaning your tools and such.. lol! But hey, that's all we get here in the States 91 on a good day.

My thinking is that, if the notorious BMW crank harmonics can be sorted out then, you might be able to raise the rev limiter to about 7800rpm, picking up more power on top. The head flows nicely, a nice port and polish, oversized intake valves, lightweight lifter buckets and you should be able to support 7800, no problems.
IMHO, the 84mm crank is just about perfect. I have yet to hear anyone blowing up either a 2.5 or 2.8l crank in their motors, unlike the 3.0.
Using the long rods will drop piston speeds and side loads and less pounding on the crankshaft. Furthermore, using the M54B25 pistons should help as they are probably lighter than the b30 (haven't confirmed this yet)


Anyhow, I am after more revs. More revs should yield more top end power. 7800 is reasonable.

The video you posted is some Swedish BMW cup car build. Don't know much about it but sounds nice nevertheless.
I am more familiar with WTCC as we have a friend who drives for Honda but used to drive for BMW. Also, a good friend of mine owns a team in Le Mans. They are based out of Switzerland.

Last edited by bayern_munchen; 07-18-2015 at 01:44 PM.
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Old 07-18-2015, 09:06 PM   #6
Rob43
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Trust me when I say I have done NO research on your subject of installing long rods, I happened to be shopping on Ebay & came across these.

I saw "BMW" and a rod length of "140mm & 142mm", the rest is up to you.....

http://www.ebay.com/itm/131497838771...e&talgo=origal

http://www.ebay.com/itm/131499014116...e&talgo=origal


Rob43
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Nitrous is a little trickier than boost, but it's not the spray that kills motors, it's STUPIDITY!!
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Old 07-27-2015, 06:40 PM   #7
Hobbit382
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Quote:
Originally Posted by bayern_munchen View Post
You are probably referring to Honda's K20/K24 platform. Hey, you brought up HONDA and, not I...

I actually happen to have a fair amount of experience with the K24 block. With it's 87mm bore and 99mm (!) stroke, the 2.4l K24 will rev 8000 rpm with factory internals and close to 9000 with aftermarket lightweight rods. This, btw in a street-tune configuration. At 8500rpm, piston speeds will be over 8000fps. These motors make power all the way to red-line or about 8200-8500 rpm with a fairly flat torque curve from 2500 to 5000rpm. Speaking of pistons, a typical 'street tune' setup consist of 12.5:1 compression ratio running US pump gas 91 octane. I know, in Germany and central EU, 91 octane is used for cleaning your tools and such.. lol! But hey, that's all we get here in the States 91 on a good day.

My thinking is that, if the notorious BMW crank harmonics can be sorted out then, you might be able to raise the rev limiter to about 7800rpm, picking up more power on top. The head flows nicely, a nice port and polish, oversized intake valves, lightweight lifter buckets and you should be able to support 7800, no problems.
IMHO, the 84mm crank is just about perfect. I have yet to hear anyone blowing up either a 2.5 or 2.8l crank in their motors, unlike the 3.0.
Using the long rods will drop piston speeds and side loads and less pounding on the crankshaft. Furthermore, using the M54B25 pistons should help as they are probably lighter than the b30 (haven't confirmed this yet)


Anyhow, I am after more revs. More revs should yield more top end power. 7800 is reasonable.

The video you posted is some Swedish BMW cup car build. Don't know much about it but sounds nice nevertheless.
I am more familiar with WTCC as we have a friend who drives for Honda but used to drive for BMW. Also, a good friend of mine owns a team in Le Mans. They are based out of Switzerland.
get a vac/ati dampener, problem solved. but fyi just because you rev a motor to 10k wont automatically make more power. the intake, head, cams, exhaust all have to be able to flow that well also. so lets think about this...

porting head 1500-3k
highly aggressive cams 1500
springs retainers lifters 2k
ati dampener 1k
exhaust 1k
intake setup 1k

so what 8k+? for tops 350whp and an engine that wont last long?

money is better spent elsewhere.
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Old 07-27-2015, 08:12 PM   #8
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Quote:
Originally Posted by daniel_f. View Post



-> !!!

Good lord that car sounds sick!
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