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Post by wannabe on Jan 28, 2021 21:50:07 GMT
Just a random thought... but would fitting pistons with a domed top, so they ended up being proud of the block at the top of their movement but not so much that they interfered with valve clearance, not reduce capacity by reducing 'space in the tube'?
Or is capacity 'bore x stroke' and that's it? And the above would create ridiculous compression ratios?? lol
[/idle mind]
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Post by Zed. on Jan 28, 2021 22:28:06 GMT
I have been a Naughty Boy !! I have just ordered a Boundary VVT oil pump. The first part of the mad short stroke build. I'd say thats hardly naughty, ordering ~£2K drysump might get a reaction & end up standing in the corner.... or on the Naughty step...  Rich. |
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Post by Zed. on Jan 28, 2021 22:29:23 GMT
Just a random thought... but would fitting pistons with a domed top, so they ended up being proud of the block at the top of their movement but not so much that they interfered with valve clearance, not reduce capacity by reducing 'space in the tube'? Or is capacity 'bore x stroke' and that's it? And the above would create ridiculous compression ratios?? lol [/idle mind] swept area is unaffected with crown design... Rich. |
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Post by warpspeed on Jan 29, 2021 2:26:33 GMT
Don't laugh, but a Mazda BP-4W cylinder head (or any BP cylinder head) bolts straight onto the top of a B M W 318i cylinder block !!
That opens up a LOT of rather interesting possibilities. For the original poster in this thread, how about a B M W M40 engine as a basis ?
84mm bore, 81mm stroke, 1796cc and with 140mm long conrods (1.73 rod ratio) for the under 1.8 litre racing class?
That is the smallest and most humble B M W combination, but would be a real rocket with a Mazda BP-4W cylinder head bolted on top.
Much better internal engine dimensions than a BP, and a far better basis to start from. Basically the head bolts straight on, the water passages all line up, and are perfect for a rear wheel drive engine application without any coolant re routing. But you will need to feed oil to the cylinder head externally. It also needs some fabrication to fit the two BP cam idler pulleys onto a thick aluminium plate, and a Gates T197 147 tooth cam belt with two extra teeth. Neither B M W or BP water pumps will work, but an electric pump solves the cooling problem. B M W have used electric water pumps across their entire engine range for many years, so it can work.
What makes all this interesting and worthwhile, is that the B M W block is 5mm taller than the BP block, and the bores are larger. The extra space gives room for a much better bore to stroke ratio, and much more happy con rod ratio with less piston side thrust, and piston rock, if you want to build a longer lasting high rpm screamer, or a high boost high torque forced induction engine. Or alternatively you could just build a big (over two litre) simple stroker engine for the street, if that is your thing.
Main bearings are 60mm not 50mm as in the BP, and its a deep skirt block, much stiffer.
My block it the M44 which has the larger 55mm bore plus some standard oil squirters. Piston compression height is 31.5mm, same as BP, so "BP type pistons" would give the same compression ratio as original with a BP cylinder head.
Only other mod is the sump. I am using an M44 sump reduced in depth at the back with a flat plate, front of sump is 20mm deeper than BP but should clear the rack. You will need to run all B M W engine accessories, alternator, starter, power steering pump which saves a lot of work. The really nice part is the stronger Getrag gearboxes bolt straight up. Plenty of choice of engine capacity from different B M W blocks and cranks, 84mm and 85mm standard bores, the B M W guys bore them out to 87mm ! Different cranks from 81mm to 88mm stroke are available mostly cast cranks though, although some are forged.
Over two litres is possible by mixing standard B M W parts , and all with the nice long 140mm rods.
Plenty of different gearboxes too, five and six speeds with several different ratio sets bolt straight up. Clutches are no problem, B M W use the same flywheel and bellhousing sizes for four, six, and eight cylinder engines, so there are some very strong clutch combinations, all factory, and all very drivable. The B M W flywheel ring gear has the same diameter, tooth count, and pitch as BP. Don't know if its against Forum rules to post a link to another Forum, but....
I have no way of posting pictures here, but if any of you you are still in total stunned disbelief, you will find some pictures here:
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Post by dadbif on Jan 29, 2021 9:01:41 GMT
I note that one of our more “imaginative” members has already been posting on that thread...
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Post by Zed. on Jan 29, 2021 9:36:59 GMT
Don't laugh, but a Mazda BP-4W cylinder head (or any BP cylinder head) bolts straight onto the top of a B M W 318i cylinder block !!
That opens up a LOT of rather interesting possibilities. it is an interesting concept, 2L base in an early mx5  I note that one of our more “imaginative” members has already been posting on that thread... ha... that Bavarian-Murder-Weapon engine is easily available so it would be a great project... maybe I'll look @ their 1.6 block......  Rich. |
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Post by warpspeed on Jan 29, 2021 10:06:14 GMT
ha... that Bavarian-Murder-Weapon engine is easily available so it would be a great project... maybe I'll look @ their 1.6 block...... Rich. Yes, the B M W guys look down upon the four cylinder engines as old obsolete underpowered inefficient boat anchors. The one to get initially would be the M40 in either 1.6 or 1.8 size. Its the only one that uses a belt driven overhead cam, and has the special oil pump with a front oil seal.
All the later engines use a timing chain, so you must get an M40 oil pump from somewhere, even if you eventually settle on using a later engine anyway.
Anyone restoring a 318i would fit the optional inline six, I certainly would.
So plenty of old B M W M4x four banger engines available out there for scrap prices.
Good victim material for some secret experimentation at a very affordable price. Get it running in stock form first with a good Miata cylinder head, and sort out the engine mounts, gearbox, gear change, and tailshaft, plus some engine management, then once its running reliably, pull it out again, and then do it properly with forged parts and proper balancing and tuning. That is the grand plan here.
So initially not chasing power or performance, just try to get it mobile and running reliably for absolute minimum dollars, solving all the small and interesting problems as I go.
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Post by wannabe on Jan 29, 2021 18:24:44 GMT
Don't laugh, but a Mazda BP-4W cylinder head (or any BP cylinder head) bolts straight onto the top of a B M W 318i cylinder block !!
That opens up a LOT of rather interesting possibilities. For the original poster in this thread, how about a B M W M40 engine as a basis ?
84mm bore, 81mm stroke, 1796cc and with 140mm long conrods (1.73 rod ratio) for the under 1.8 litre racing class?
That is the smallest and most humble B M W combination, but would be a real rocket with a Mazda BP-4W cylinder head bolted on top.
Much better internal engine dimensions than a BP, and a far better basis to start from. Basically the head bolts straight on, the water passages all line up, and are perfect for a rear wheel drive engine application without any coolant re routing. But you will need to feed oil to the cylinder head externally. It also needs some fabrication to fit the two BP cam idler pulleys onto a thick aluminium plate, and a Gates T197 147 tooth cam belt with two extra teeth. Neither B M W or BP water pumps will work, but an electric pump solves the cooling problem. B M W have used electric water pumps across their entire engine range for many years, so it can work.
What makes all this interesting and worthwhile, is that the B M W block is 5mm taller than the BP block, and the bores are larger. The extra space gives room for a much better bore to stroke ratio, and much more happy con rod ratio with less piston side thrust, and piston rock, if you want to build a longer lasting high rpm screamer, or a high boost high torque forced induction engine. Or alternatively you could just build a big (over two litre) simple stroker engine for the street, if that is your thing. Main bearings are 60mm not 50mm as in the BP, and its a deep skirt block, much stiffer.
My block it the M44 which has the larger 55mm bore plus some standard oil squirters. Piston compression height is 31.5mm, same as BP, so "BP type pistons" would give the same compression ratio as original with a BP cylinder head.
Only other mod is the sump. I am using an M44 sump reduced in depth at the back with a flat plate, front of sump is 20mm deeper than BP but should clear the rack. You will need to run all B M W engine accessories, alternator, starter, power steering pump which saves a lot of work. The really nice part is the stronger Getrag gearboxes bolt straight up. Plenty of choice of engine capacity from different B M W blocks and cranks, 84mm and 85mm standard bores, the B M W guys bore them out to 87mm ! Different cranks from 81mm to 88mm stroke are available mostly cast cranks though, although some are forged.
Over two litres is possible by mixing standard B M W parts , and all with the nice long 140mm rods. Plenty of different gearboxes too, five and six speeds with several different ratio sets bolt straight up. Clutches are no problem, B M W use the same flywheel and bellhousing sizes for four, six, and eight cylinder engines, so there are some very strong clutch combinations, all factory, and all very drivable. The B M W flywheel ring gear has the same diameter, tooth count, and pitch as BP. Don't know if its against Forum rules to post a link to another Forum, but....
I have no way of posting pictures here, but if any of you you are still in total stunned disbelief, you will find some pictures here:
This is all pretty awesome, thanks for posting the info  I guess the question that needs to be asked is 'why bother with the Mazda cylinder head and all the faff to mate the two if, in theory, the Tailgate McNoIndicate will drop in and run as a whole unit'? What's the power output of the Beemer engine? What would the power output be for a 2.0 N/A engine using the Beemer bottom end and the Mazda top end? Does the Mazda top end just have higher flow, therefore higher power potential? Does the over-square (is that the correct term?) bottom end mean it will be nice and revvy, similar in style to the early 1.6 Short Nose Crank engine? A torque-tastic 2.0 that was also super-revvy would be excellent TBH How much weight difference would there be with the new arrangement and all the Tailgate McNoIndicate ancillaries? |
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Post by dickie on Jan 29, 2021 18:24:49 GMT
Hi Warpspeed,
Very interesting stuff thank you for sharing it.
For my project I have to keep with original Mazda engine block.
I compete in the roadgoing class the MSUK rules limit the engine to the original manufactures engine as fitted to the model series.
I can not change from a five speed to a six speed gearbox.
All the work I am planning will be as per a forged engine but with a custom bullet crankshaft added to the build.
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Post by warpspeed on Jan 29, 2021 20:54:53 GMT
Hi wannabe, for some reason the Forum software has a brain fart if you use the letters B M W without the extra spaces between the letters. It comes out as "Tailgate McNoIndicate" haha, have no idea why it does that. Very odd... O/k, all the B M W four bangers are mounted at forty five degrees in the original cars, and the hot side and cold side are the opposite way around. So using the the original DOHC chain driven head, creates a lot more problems than it solves. By using a Mazda head, and mounting the engine vertical, we get an excellent cylinder head, it looks more original Miata, and we get to use a lot of original parts such as the induction system (ITB ?) and exhaust. It basically still looks sort of original at first glance, but with a lot of future potential for higher rpm and longer engine life. Its also possible to use all the original Miata turbo stuff that many guys here already have, although the starter motor location may be problematic for the dump pipe, or maybe not. I don't yet have a starter motor here to judge by. All the original B M W accessories mount on the hot side, but easily clear the front of a turbo. The cold side of the block is completely bare, the starter and oil filter are on the hot side. So that leaves plenty of room for a really big cold side supercharger mounted BELOW the intake manifold. I may actually do that, as I have a front entry TVS1320 that would fit very nicely. We shall see.....
Its also going to cost less to fit a B M W engine block to a Getrag gearbox than buy an expensive adapter plate and flywheel to fit a Getrag to a BP engine. The serious forced induction guys know the Mazda gearboxes jut are not up to the job. So it solves quite a few problems at the expense of a bit more messing about, although the modifications required are all fairly straightforward. So generally it could save a lot of money, because a lot of expensive parts that people already have can be reused. It will be heavier though, but probably not by a lot. The block is a deep skirt design that has a completely flat gasket surface well below crank level, and the block is 5mm taller.So more metal means more weight. The crank has much larger main bearings, 60mm versus 50mm for the BP, so the crank is going to be stiffer and heavier, but again probably the extra actual weight may not be all that more. There are several flywheels for these engines, the most common is a dual mass flywheel, which is actually two separate flywheels linked by a huge spring. One flywheel is bolted rigidly to the crank. The second flywheel has a centre bearing, and the pressure plate is bolted onto that. The clutch plate has a solid hub with no springs.
I am told that the whole mess with pressure plate weighs 27 Lbs, but it produces a very smooth drive train. This would be an advantage for the supercharger guys that make a lot of low rpm torque, where only having four cylinders, creates a lot of torsional fluctuations. Some of these engines also have more conventional flywheels and clutches, which should be available secondhand, which might be a lot more suitable for hot normally aspirated engine, or for turbo operation. I am going to use the dual mass flywheel that is already on the engine and see how it goes. So heavier block, heavier crank, and maybe a much heavier flywheel. But I have not weighed any of it yet, although I definitely plan to do so at some stage. Plenty to think about, and I will just see how it all goes. |
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Post by Zed. on Jan 29, 2021 21:06:46 GMT
Hi wannabe, for some reason the Forum software has a brain fart if you use the letters B M W without the extra spaces between the letters. It comes out as "Tailgate McNoIndicate" haha, have no idea why it does that. Very odd... it's because a child setup the fu ckin swear filter  it's easy to type BMW if you want.... Rich. |
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Post by warpspeed on Jan 29, 2021 22:58:59 GMT
Hi wannabe, for some reason the Forum software has a brain fart if you use the letters B M W without the extra spaces between the letters. It comes out as "Tailgate McNoIndicate" haha, have no idea why it does that. Very odd... it's because a child setup the fu ckin swear filter it's easy to type BMW if you want.... Rich.
I know quite a few swear words Rich. But in my complete total innocence do not know what B M W means, apart from Bavarian Motor Works.
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Post by Zed. on Jan 29, 2021 23:17:18 GMT
I know quite a few swear words Rich. But in my complete total innocence do not know what B M W means, apart from Bavarian Motor Works.
 Rich. |
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Post by warpspeed on Jan 29, 2021 23:20:42 GMT
Been doing some serious research here guys with the on line aconyms dictionary. How about Bavarian Manure Wagon
Also something (probably about hot dogs) Bite My Weenie
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Post by wannabe on Jan 30, 2021 1:34:54 GMT
Hi wannabe, for some reason the Forum software has a brain fart if you use the letters B M W without the extra spaces between the letters. It comes out as "Tailgate McNoIndicate" haha, have no idea why it does that. Very odd... O/k, all the B M W four bangers are mounted at forty five degrees in the original cars, and the hot side and cold side are the opposite way around. So using the the original DOHC chain driven head, creates a lot more problems than it solves. By using a Mazda head, and mounting the engine vertical, we get an excellent cylinder head, it looks more original Miata, and we get to use a lot of original parts such as the induction system (ITB ?) and exhaust. It basically still looks sort of original at first glance, but with a lot of future potential for higher rpm and longer engine life. Its also possible to use all the original Miata turbo stuff that many guys here already have, although the starter motor location may be problematic for the dump pipe, or maybe not. I don't yet have a starter motor here to judge by. All the original B M W accessories mount on the hot side, but easily clear the front of a turbo. The cold side of the block is completely bare, the starter and oil filter are on the hot side. So that leaves plenty of room for a really big cold side supercharger mounted BELOW the intake manifold. I may actually do that, as I have a front entry TVS1320 that would fit very nicely. We shall see.....
Its also going to cost less to fit a B M W engine block to a Getrag gearbox than buy an expensive adapter plate and flywheel to fit a Getrag to a BP engine. The serious forced induction guys know the Mazda gearboxes jut are not up to the job. So it solves quite a few problems at the expense of a bit more messing about, although the modifications required are all fairly straightforward. So generally it could save a lot of money, because a lot of expensive parts that people already have can be reused. It will be heavier though, but probably not by a lot. The block is a deep skirt design that has a completely flat gasket surface well below crank level, and the block is 5mm taller.So more metal means more weight. The crank has much larger main bearings, 60mm versus 50mm for the BP, so the crank is going to be stiffer and heavier, but again probably the extra actual weight may not be all that more. There are several flywheels for these engines, the most common is a dual mass flywheel, which is actually two separate flywheels linked by a huge spring. One flywheel is bolted rigidly to the crank. The second flywheel has a centre bearing, and the pressure plate is bolted onto that. The clutch plate has a solid hub with no springs.
I am told that the whole mess with pressure plate weighs 27 Lbs, but it produces a very smooth drive train. This would be an advantage for the supercharger guys that make a lot of low rpm torque, where only having four cylinders, creates a lot of torsional fluctuations. Some of these engines also have more conventional flywheels and clutches, which should be available secondhand, which might be a lot more suitable for hot normally aspirated engine, or for turbo operation. I am going to use the dual mass flywheel that is already on the engine and see how it goes. So heavier block, heavier crank, and maybe a much heavier flywheel. But I have not weighed any of it yet, although I definitely plan to do so at some stage. Plenty to think about, and I will just see how it all goes. Thanks for the detailed reply! The empty cold side sounds interesting in terms of space created - as you say, ideal for a charger addition I'm guessing a B M W gearbox wouldn't be too difficult to adapt to fit the '5 mountings? The dual mass flywheel sounds expensive if it goes wrong - I recall the Ford S-Max uses those, and it's usually more than the whole car is worth nowadays... lol Overall, it sounds very interesting, especially in terms of a potential revvy-but-torquey 2.0 conversion ('charged or not), but it also sounds fiendishly tricky to get right. Just the sort of thing Zed. would like LoL  |
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le sigh