Originally posted by digger
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Originally posted by whodwho View PostTime to eliminate it and dry sump it then! 8^)
a bigger crank wont bring anymore hp anyway just lower the rpm where the peak is made (where you choke the head). this of course means more torque which would be good on the street though no need to ring its neck to make it go.89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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Originally posted by whodwho View PostTime to eliminate it and dry sump it then! 8^)
Originally posted by digger View Posta bigger crank wont bring anymore hp anyway just lower the rpm where the peak is made (where you choke the head). this of course means more torque which would be good on the street though no need to ring its neck to make it go.'87 5-speed 325is
The best $750 I ever spent!
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Originally posted by CrazyJew89 View PostOnly if you manage to get one of those cranks
I'm all about more torque and making the motor have more low end than high end power. To me it is the key to a fun street motor.89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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Build more torque (and not just shift where you are making it), you are going to make more horsepower. Can't build one without the other, so increasing the stroke and capacity is going to result in more power. Has TK even found the absolute limit yet, in terms of flow potential I mean? It seemed more like he had the flow figures and potential, but the result surprised even him. Would be a different way to go about it reaching the maximum potential though, wouldn't need the revs and probably such an aggressive camshaft with the added capacity.
I don't even think you would be able to run a stroke that big within the confines of the block. Rod angle would be pretty extreme, a 140mm rod would leave you about 18mm compression height which isn't going to work. Lowest I've ever seen is about 20mm I think, and im not sure if you would be able to get a 22mm pin in there at that thickness. Even if you went to a 135mm rod, I reckon you might struggle to get any of the usual piston companies to produce you a piston to suit, and that's if the rod angle doesn't cause problems at bdc. If you have to start sleeving the block because of the added stroke, you'll reduce the clearance even further.Just a little project im working on
- http://www.lse30.com -
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Originally posted by Madhatter View PostBuild more torque (and not just shift where you are making it), you are going to make more horsepower. Can't build one without the other, so increasing the stroke and capacity is going to result in more power. Has TK even found the absolute limit yet, in terms of flow potential I mean? It seemed more like he had the flow figures and potential, but the result surprised even him. Would be a different way to go about it reaching the maximum potential though, wouldn't need the revs and probably such an aggressive camshaft with the added capacity.
I don't even think you would be able to run a stroke that big within the confines of the block. Rod angle would be pretty extreme, a 140mm rod would leave you about 18mm compression height which isn't going to work. Lowest I've ever seen is about 20mm I think, and im not sure if you would be able to get a 22mm pin in there at that thickness. Even if you went to a 135mm rod, I reckon you might struggle to get any of the usual piston companies to produce you a piston to suit, and that's if the rod angle doesn't cause problems at bdc. If you have to start sleeving the block because of the added stroke, you'll reduce the clearance even further.
i think the focus should be more on correct induction and exhaust (sizing an length) and quality of burn than getting a few more CFM.
if you look at MM engines they use a 139.75 mm rod with 86mm stroke. that is a nominal compression height of.
206.0-139.75-43=23.25mm
Take the extreme case of HIOP 95.8mm stroke with 135mm rod using 23.0 mm comp height
206.0-23.0- 47.9=135.1mm, so use a stock length rod
Check clearance bottom of piston boss to crank CW
-47.9+135=87.1
Assume R70.5mm counterweight same as S52
You have 87.1-70.5 = 16.6 to fit the following
-Clearance between counterweight and piston boss say 2mm.
-Piston Boss wall thicknesses say 5mm
-Piston pin radius.
Leaves a piston pin with radius
16.6-5-2=R9.6mm
or D19mm
Theoretically possible with a heavy wall thickness
This is assuming the crank CW is only 71mm radius if not you need to machine it and rebalance or you are screwed.
You can go even smaller on the comp height of the piston but you need to consult a piston guy to look at options. I wouldn’t ever use a 2 ring piston except on drag engine that does a few passes and is torn down regularly. A compromised ring pack will hurt you more by virtue of poorer ring seal than you gain by a few more cubic inches.
I think the intermediate shaft would need to be about D12-13mm which is quite a bit thinner than the 18mm stock. The clearance to the bore would need a decent chamfer.
I think you could get it to work but don’t know how good it would be. BMW/Alpina used a 135mm rod with the 93.8 crank and a 21mm pin. This shows what BMW thought about rod ratio couldn’t care less it seems still came with warranty. The VAC S54 strokers are even worse for rod ratio……..They have extra deck height to play with and ended up with 305bhp and 270lbft in the B3S which is well above the M50/52/S52 engines.Last edited by digger; 01-30-2014, 06:01 PM.89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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Originally posted by Madhatter View PostBuild more torque (and not just shift where you are making it), you are going to make more horsepower. Can't build one without the other, so increasing the stroke and capacity is going to result in more power.
Increasing the stroke will result in more torque which at a given rpm will produce more hp, this does not apply equally across the rpm band though. Generally the peak tourque rpm is lowered and the max hp number at high rpms is not always increased.
Edit: Damn i'm a slow typer.
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That's why I said, have we even found the limit of the head yet, because it seemed like Tony wasn't really sure just how much power it would actually develop vs it's potential. You are just assuming the head is now the restriction.
Yeah, the problem in development of a huge stroke is fitting the ring pack and crown in the same space, which the usual piston suppliers have a bit of a cry about. I wasn't saying one couldn't be made, but i don't see it happening without some concessions, one of which is cost, another is reducing the pin diameter which means rods too.
Yeah, I wasn't talking about the combination fouling on the crank counterweights, more that increased stroke changes the rod angle in relation to the block and the bottom of the bore and side of the block. What did you end up with before to the block and rod? about 5mm? Was Wondering if there would be enough room for the rod to clear as the added stroke is going to push the rod closer to the block.
You can see why bmw made the M50 block taller when they replaced the M20. Even just a few mm is enough to make a difference with much longer strokes.Just a little project im working on
- http://www.lse30.com -
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Originally posted by Madhatter View PostThat's why I said, have we even found the limit of the head yet, because it seemed like Tony wasn't really sure just how much power it would actually develop vs it's potential. You are just assuming the head is now the restriction.
Yeah, the problem in development of a huge stroke is fitting the ring pack and crown in the same space, which the usual piston suppliers have a bit of a cry about. I wasn't saying one couldn't be made, but i don't see it happening without some concessions, one of which is cost, another is reducing the pin diameter which means rods too.
Yeah, I wasn't talking about the combination fouling on the crank counterweights, more that increased stroke changes the rod angle in relation to the block and the bottom of the bore and side of the block. What did you end up with before to the block and rod? about 5mm? Was Wondering if there would be enough room for the rod to clear as the added stroke is going to push the rod closer to the block.
You can see why bmw made the M50 block taller when they replaced the M20. Even just a few mm is enough to make a difference with much longer strokes.
nevertheless getting much more CFM from the head in a way that translate into more power (burns properly, correct velocity etc) is limited and will ultimately limit the peak power possible. once the head has an efficient Cd (shape) all you can do is get the size bigger to a limit of the casting, layout and size of the valves, chamber shape etc to turn more rpm. TK wasnt that far from this on the race engine.
there is a limit to how much power you can make with a given CFM and head characteristics and fuel, changing the stroke will for the most part only affect the rpm where it happens. there is more tunability in higher rpm so a smaller higher rpm engine has a bit of an advantage with wave tuning etc
if i run a sim on my engine with more cubic inches all i do is get more torque no more peak power but it peaks a few hundred rpm earlier.....its not until i start influencing the head flow and cam profile do i start getting much higher peak hpLast edited by digger; 01-30-2014, 07:13 PM.89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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Originally posted by Madhatter View PostYeah, I wasn't talking about the combination fouling on the crank counterweights, more that increased stroke changes the rod angle in relation to the block and the bottom of the bore and side of the block. What did you end up with before to the block and rod? about 5mm? Was Wondering if there would be enough room for the rod to clear as the added stroke is going to push the rod closer to the block.
You can see why bmw made the M50 block taller when they replaced the M20. Even just a few mm is enough to make a difference with much longer strokes.89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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Originally posted by digger View Postthere is a limit to how much power you can make with a given CFM and head characteristics and fuel, changing the stroke will for the most part only affect the rpm where it happens. there is more tunability in higher rpm so a smaller higher rpm engine has a bit of an advantage with wave tuning etc
if i run a sim on my engine with more cubic inches all i do is get more torque no more peak power but it peaks a few hundred rpm earlier.....its not until i start influencing the head flow and cam profile do i start getting much higher peak hp
11.5mm increase in throw is a big difference and you have a small margin as it is, think it's going to be closer than you think. I wouldn't be surprised if its one of the reasons why companies like MM have gone with a much longer rod on purpose, even having some made which will reduce the angle. Now we are reducing the length of the rod and increasing the stroke over those combinations which could be a problem. They note in their own info that when going to 89.6 mm stroke of the M3, the rod can already strike the block in their sport engines with a 135mm rod. So I think you can be pretty certain the further increase in stroke is going to be a problem at some point. Interesting to note they went to 138mm rods on the rally 3.2L engines, 206 - (138 + 44.8 ) = 23.2mm. Wouldn't be surprised if they reduced the pin diameter to due to the piston/rod combination too, but there is obviously a point where things physically won't fit or can't be made reliable otherwise they could have just run a longer 140mm rod they already had to reduce the angle further. All conjecture though of course until someone want's to give it a try though. I've seen them use doweled sandwich plates between the block and the head, then sleeved the block to increase deck height before, kind of old school I guess and you don't see it a lot anymore. I guess if you were hell bent on creating the biggest capacity M20, it's not that big a deal to give everything a try.Last edited by Madhatter; 01-30-2014, 07:59 PM.Just a little project im working on
- http://www.lse30.com -
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Originally posted by Madhatter View PostThe above is only true if the flow capacity of the head remains the same though. I wasn't suggesting that increasing the capacity will develop more power if you are already at max VE.89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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has anyone ever heard of a broken intermediate shaft? i am referring to the shaft not the gear that used to be pressed89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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Originally posted by tinkerputzer View PostNope. Maybe give mm a call. I would think the oil pump drive shaft would give out before the intemediate shaft.
my thinking is the shaft is stressed in bending due to the belt tension. the bending moment is highest at the front bearing of the block and where you notch it out is midway between the two bearings so bending moment is only half the maximum. so it makes sense to locally notch it with a nice transition shape not like the sharp corner the MM put really close to the high bending moment areas. the one i have from MM is 17.75mm diameter ending in a sharp notch. i bet you could go alot thinner midway between the bearings with better shape and not impact fatigue life. perhaps you could polish or peen it aswell
the torsion loads are small enough to be carried by the skinny oil pump hex drive so wont affect the main shaft at all89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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