Which powerful non turbo engines are there under 3.0?
Discussion
In middle of building a new rally car to replace my current BMW M3 Compact fitted with an E36 M3 engine (see www.team-notax.co.uk for details)
Sadly due to rally rules I have to use a non turbo engine and keep below 3.0 so a 3.2 M3 is not available and nor are more recent turbo engines. Ideally looking for an engine which weighs less than the S50 (E36 M3) and can be tuned to gived more power and torque. Are there any options?
Sadly due to rally rules I have to use a non turbo engine and keep below 3.0 so a 3.2 M3 is not available and nor are more recent turbo engines. Ideally looking for an engine which weighs less than the S50 (E36 M3) and can be tuned to gived more power and torque. Are there any options?
There`s a HUGE amount of options all depending on what you want to spend and what longevity you want between rebuilds. The S50 and S52 are both weighty so what bout going to a more highly tuned 2.0 four? Mitsubishi evo engine sans turbo could be coaxed to produce about 330bhp with all forged internals, the old vauxhall red top 16v on throttle bodies, all steel internals can be coaxed to 320ish and would be a lot cheaper than the EVO engine. Even the old cossie lump, although heavier than both of the above can give you reliable high output N/A power.
More modern engines such as the 2.5 Ford would give you higher figures as would the VW/Audi 5cyl 2.5 but you are again looking at £000`s to get the big numbers.
The 328i would be a big step backwards. how about using a sleeved down S52? Pretty pricey way of doing it I would think though?
If I was in your shoes I would be talking with Swindon Race Engines, masters at N/A tuning within strict motorsport regulations.
More modern engines such as the 2.5 Ford would give you higher figures as would the VW/Audi 5cyl 2.5 but you are again looking at £000`s to get the big numbers.
The 328i would be a big step backwards. how about using a sleeved down S52? Pretty pricey way of doing it I would think though?
If I was in your shoes I would be talking with Swindon Race Engines, masters at N/A tuning within strict motorsport regulations.
Righto, 1st things first, if you are allowed 3 litres, then you absolutely have to use ALL of that (say 2.999l !!) otherwise you are just giving away performance.
The problem being 3l is large for just 4 cylinders, on a six it give you a resonable 500cc per cyl, any larger than this and you are going to run into burnrate limitiations, reducing max rpm and hence total power output.. Assuming that costs are a limitation, probably the cheapest option is a short stroke crank for the M3 engine, as you would have to do nothing to your car to use it really. Also you already have the breathing in place for 300+bhp, so maybe with some cam timing mods and an increase in CR you could probably maintain your current bhp output but at a higher rpm(you will loose a small amount of torque however due to the capacity reduction)
off the top of my head i cant think of any sensible 4cyl 3 litres apart from the porsche engine, and that will be V expensive to tune. If you need to get weight out of the 6yl, there will be ways to do that (think CF cam cover/sump/intake etc) Also, subtle block machining can typically get 15% off the bare block mass for a proddy block
Edit to add: the S50B32 engine (3.2l) has a bore of 86.4mm and a stroke of 91mm, if the crank from a M52B28 fits (??no idea if it would) this would give you 2955cc on it's 84mm stroke, or perhaps you could offset grind the conrod pins from the 3.0litre version down towards the 85.25mm optimum number??
From a pure weight perspective, it would be better to start with the ally blocked N52 engine, and effectively try to pack in as much valve area as possible within the 84mm bore constraints
The problem being 3l is large for just 4 cylinders, on a six it give you a resonable 500cc per cyl, any larger than this and you are going to run into burnrate limitiations, reducing max rpm and hence total power output.. Assuming that costs are a limitation, probably the cheapest option is a short stroke crank for the M3 engine, as you would have to do nothing to your car to use it really. Also you already have the breathing in place for 300+bhp, so maybe with some cam timing mods and an increase in CR you could probably maintain your current bhp output but at a higher rpm(you will loose a small amount of torque however due to the capacity reduction)
off the top of my head i cant think of any sensible 4cyl 3 litres apart from the porsche engine, and that will be V expensive to tune. If you need to get weight out of the 6yl, there will be ways to do that (think CF cam cover/sump/intake etc) Also, subtle block machining can typically get 15% off the bare block mass for a proddy block
Edit to add: the S50B32 engine (3.2l) has a bore of 86.4mm and a stroke of 91mm, if the crank from a M52B28 fits (??no idea if it would) this would give you 2955cc on it's 84mm stroke, or perhaps you could offset grind the conrod pins from the 3.0litre version down towards the 85.25mm optimum number??
From a pure weight perspective, it would be better to start with the ally blocked N52 engine, and effectively try to pack in as much valve area as possible within the 84mm bore constraints
Edited by anonymous-user on Sunday 11th July 14:48
Thanks for the replies 
I'm keen to stick with BMW power - the current 3.0 E36 M3 lump has been very reliable, I'm just keen to up the power and lower the weight on the new one if possible.
I have a mint 3.2 M3 available but am not sure of the best way to bring it down to 3.0 litres - or what impact this would have on the power and torque. I see the 130i engine is 3.0 and puts out 268bhp (less than the stock E36 M3 but not by much) is this a turbo'd engine? If so I can't use it - but if not maybe it is the answer if it is easily tunable...
I'm keen to stick with BMW power - the current 3.0 E36 M3 lump has been very reliable, I'm just keen to up the power and lower the weight on the new one if possible.I have a mint 3.2 M3 available but am not sure of the best way to bring it down to 3.0 litres - or what impact this would have on the power and torque. I see the 130i engine is 3.0 and puts out 268bhp (less than the stock E36 M3 but not by much) is this a turbo'd engine? If so I can't use it - but if not maybe it is the answer if it is easily tunable...
anonymous said:
[redacted]
Because the 3.2 has had all the top end development in ports, cams, followers, valves etc to support 100bhp/l and the high revs that are required to do that. Also it comes with induvidual throttles as std, and a decent tubular exhaust manifold etc. I bet that with some selective machining you can get the weight of the 3.2 block down very close to that of the later ally engines, and avoid all the nicasil coated liner knightmares etc??You need to shorten the stroke, NOT reduce the bore!
So you need to look at trying to find a crankshaft that will fit that has a shorter stroke, or one that is close, that you can offset grind the pins (hence shortening the stroke) or, if all else fails, get someone like Arrow (http://www.arrowprecision.co.uk/) to make you a new billet one. (You'll be looking at about £2.5k for that)
Shortening the stroke will reduce piston speed, reducing friction, and allowing the engine to rev more, If you sleeve the block you will shroud the valves reducing volumetric efficiency, not good!
So you need to look at trying to find a crankshaft that will fit that has a shorter stroke, or one that is close, that you can offset grind the pins (hence shortening the stroke) or, if all else fails, get someone like Arrow (http://www.arrowprecision.co.uk/) to make you a new billet one. (You'll be looking at about £2.5k for that)
Shortening the stroke will reduce piston speed, reducing friction, and allowing the engine to rev more, If you sleeve the block you will shroud the valves reducing volumetric efficiency, not good!
Max_Torque said:
You need to shorten the stroke, NOT reduce the bore!
So you need to look at trying to find a crankshaft that will fit that has a shorter stroke, or one that is close, that you can offset grind the pins (hence shortening the stroke) or, if all else fails, get someone like Arrow (http://www.arrowprecision.co.uk/) to make you a new billet one. (You'll be looking at about £2.5k for that)
Shortening the stroke will reduce piston speed, reducing friction, and allowing the engine to rev more, If you sleeve the block you will shroud the valves reducing volumetric efficiency, not good!
Thanks, would a 3.0 crankshaft fit a 3.2? I'm not particularly technical but this seems a logical solution... If the bore is the same does that mean I can use 3.0 pistons too?So you need to look at trying to find a crankshaft that will fit that has a shorter stroke, or one that is close, that you can offset grind the pins (hence shortening the stroke) or, if all else fails, get someone like Arrow (http://www.arrowprecision.co.uk/) to make you a new billet one. (You'll be looking at about £2.5k for that)
Shortening the stroke will reduce piston speed, reducing friction, and allowing the engine to rev more, If you sleeve the block you will shroud the valves reducing volumetric efficiency, not good!
anonymous said:
[redacted]
There is a big difference in claimed BHP and torque between the 3.0 (286 bhp) and 3.2 (321 bhp) which can't be down to just 200cc. If the gains are made in the head can I just put a 3.2 head on a 3.0 bottom end? I gather that the 3.2 sump is better than the 3.0 so maybe I could use the top end and sump off a 3.2 and put a 3.0 bottom end between the two...?anonymous said:
[redacted]
Yes I agree that mathematically you are correct but maybe the top end on the 3.2 is where most of the gains are made and hence after dropping 200cc it may still be producing well over 300bhp (although I accept it may not!) I'm not sure why, but chipping the 3.2 is apparently more successful than chipping the 3.0 too so this may add to the power advantage of a reduced size 3.2 compared to a 3.0...anonymous said:
[redacted]
Thing is, if you're building a competition car, do you want to start by giving away 14bhp?? What i have found is that engine performance actually saves you money in the long term. If your car is quick, you don't need to try as hard, much less chance of crashing through overdriving it, much less wear on everything else getting thrashed trying to make up tenths of secs on every corner.Personally, i suspect that with a decent exhaust with low back pressure and retuned lengths, with more agressive cam timings and bumping up the CR to something over 12 to 1 (run on 102 octaine fuel to keep peak torque high) you would be seeing probably 110bhp/litre at 8krpm, so 330bhp flywheel.
Gassing Station | BMW General | Top of Page | What's New | My Stuff