Internal engine geometry

[TR-Spider]

Ricky

the E30 318iS is a 4Zyl 4Valve engine (code M42), albeit with 1.8l only.
It only came as lefthand drive, 38000 made, std bhp 136 @ 6000 rpm.
Compared to the M3 it would be a low(er)cost option.
Most likely larger pistons could be used to ge for 2l (bore is only 84mm).
It is quite popular in Germany, where it has its own class in rallying.

Thomas

[Rich Ellingham]

That sounds a good option then.

Maybe still look at a ready built 318 race car - I know there's a series for them.

Rich

[Walezy]

Just to make it clear. BMW e30 320is is a 4 cylinder 2.0 liter 16v engine that should give about 190hp.

[TR-Spider]

so there are actually 3 different 4-zylinder 4-valve (per cylinder) engines for the BMW E30

Model..... Engine..... bore..... stroke..... capac.... hp/rpm
M3... ..... S14 ........ 93.4..... 84.0 ....... 2.3l..... 215/6750
320iS...... S14 ....... 93.4 ..... 72.6 ....... 2.0l ..... 192/6900
318iS..... M42........ 84 .0 ..... 81.0 ....... 1.8l..... 136/6000

The s14 engine ( 1985-1990) is quite a reference, with individual throttle bodies etc.
The M42 is a bit simpler. All 3 are dohc with chain drive.

Thomas

[trickymex]

thank you guys

I will look into the E30 with the M42 engine as i think this will be the best performance for the cost

I think this will be a more competative option than the 190E

I will report my findings

Ricky

[Walezy]

If you do any progress with that car please let me know as my friend has such car and we are slowly converting it into a rally car. First of all we will install Megasquirt EFI with 4x40mm throttle bodies just to get a bit more out of that engine. After that we will see if there is a good gain. If it is then we will go on with this engine, if notthe we will simply install Honda s2000 engine just like I did in my car.

[trickymex]

Walezy, of course i will let you know what i find

Im not sure what you have in mind but for me im going for a a very high revving almost touring car spec engine, im hoping for more than 250Bhp, BMW managed to get over 300bhp in there BTCC version of this engine so thats a goal to aim for i guess

After doing some investigating a few problems have arisen

1. The standard M42 engine has hydraulic lifters and for anything above 7k Rpm solid lifters are going to be needed, luck would have it that the S50 (3000cc E36 M3 engine) engine has parts that are interchangable to cure this problem

2. Quite a bit of head work is going to be needed, including larger valves but this is going to be needed in any case

3. There seems to be quite a few documented harmonic balancer failures and subsoquent crank breakages when you try to push the engine past 7200 Rpm for some reason, not sure why?? there are aftermarket items available though

4. the standard flywheel is a dual mass unit and not very well suited to race application but i think the M20 flywheel fits, maybe that will suit better or an aftermarket one if funds allow

Once i find out more i will post here

Ricky

[Walezy]

You could also consider using Honda S2000 for a race car. It has probably the best stock engine in the world. It can be revved to 9000rpm with no problems(but I know a person that revs it to 10000rpm and has no problems at all in a MK1 Escort). It has peak power at about 8200rpm and at the begining has 240HP. Also VTEC will be a good advantage as it will have torque in all powerband. Engine is very reliable and there are plenty of aftermarket parts available, mainly from Japan.
You can use gearkits that are my by some australian company(Pfitzner as i belive it was) or Quaife 6 speed sequential gearbox(bellhousings for type 9 gearbox are available- I even have one).
Final drive ratios are widely available as it is the same as Kia Sportage (4,77 and more aftermarket ones) or Mazda Miata ( many to choose from)

I am not sure if roadsters can be used in that race class but hardtops for this car are available.
The car weight is about 1200kg but for sure it could go down to about 1000 with use of lightweight bodyparts and a bit of work with the chasis.

[Rich Ellingham]

Ha ha, you know I just came on here to post - why not S2000. I drove one last night for the first time, wow, its really is just like a race car. It feels great, has the best gear change I've ever experienced, it would take very little to make it race ready I wouldn't even change the controls or dials, only the suspesion, brakes, radiator and add an accusump. the gearing is really close and very low geared perfect as it is for the track. Really I got out shaking my head, I know what I'd build if I wanted a 2lt NA race car. Just need to check the rules regarding a hard top cabriolet. I would urge you to try one; it would cost some really serious money to build a 240 BHP NA engine for anything else.

Rich

[trickymex]

Unfortunatly I'm pretty sure the series is for hard tops only

Also I have to use an engine that was originally fitted to the chassis so the S2000 engine in the bmw chassis is a no go

And Rich I had a S2000 for a few months last year, I got rid to get my M3, it was a great car though

[Walezy]

You can for sure get a fibreglass or even kevlar hard top for S2000. You just need to get rid of the soft top.
I use this engine in my Fiat 131 Abarth(replica of course) and it makes the car to accelerate much faster then stock BMW M3 e36 (321HP) up to the end of 4th gear, after that air drag is probably too big for my car. My Fiat is 1030kg soit is not that light. The engine and gearbox are stock with no modifications and the final drive ratio is 4,55 but i plan to fit 5,38.

[trickymex]

I have just asked someone in the kow with the rules, one of the writers of the rules and oraganisers to be precise

He said no to the S2000 as its a sports car and the DMN series is open only to saloon cars

Never mind

Ricky

[Rich Ellingham]

Better look at the LMA instead.....Saloon and sports car series. Hows an S2000 a sports car and a Audi TT not?- Did the TT have rear seats as a road car? as I know one of those raced last year in the DMN. I'd ask Rod Birley at BARC SE (Assuming that's not who you spoke to already).

rich

[Boyracer]

My first post in this excellent forum :)

I have been slowly gathering information and parts to build "semi" S42 (racing version for Class II/Supertouring rules) out of M42. Currently it only has slightly longer duration/higher lift regrinded cams and an internet auction site chip, this configuration is good to about 165-170 hp. I dynoed stock engine with chip only to have 155,6 hp.

I have Megasquirt II ready waiting for installation to give some adjustability and 3,0 liter M3 individual throttle bodies are ready to be fitted to cylinder head, they are almost straight fit since ports have identical shape and size, only bolt patterns requires slight adaptation.

I think I will post own thread about the planned modifications because it is quite extensive list and I have lots of questions about cylinder head and bottom end modifications since this is my first time building engine.

Im not sure what you have in mind but for me im going for a a very high revving almost touring car spec engine, im hoping for more than 250Bhp, BMW managed to get over 300bhp in there BTCC version of this engine so thats a goal to aim for i guess

Early 1994/95 S42 iterations had about 285 hp which was increased to around 315 hp in 1997/98. Revs were limited by Class II rules to 8500 rpm. Few bits of information about 1995 spec engine:

Bore: 86,5 mm
Stroke: 85 mm
CR: 12,4
Rod lenght: 145 mm
Intake cam: 312 / 94 degrees
Exhaust cam: 304 / 98 degrees
Intake valve: 35 mm
Exhaust valve: 32 mm

285 hp / 8300 rpm and 245 Nm / 7000 rpm

1. The standard M42 engine has hydraulic lifters and for anything above 7k Rpm solid lifters are going to be needed, luck would have it that the S50 (3000cc E36 M3 engine) engine has parts that are interchangable to cure this problem

I run my M42 with slightly more aggressive cams than stock with original hydraulic lifters and valve springs up to 7500 rpm without any problems. I know even higher speeds have been succesfully reached.

3,0 liter M3 engine (S50B30) solid lifters are not direct fit, they require longer valves and the design is shim-on-top that are somewhat suspectible to lose shims on high revs and aggressive cams. They are also quite heavy. 35 mm diameter 26 mm tall solid lifters with 14 tall mm stems commonly used in VW's should work with OEM valves with reasonably thin lash caps.

2. Quite a bit of head work is going to be needed, including larger valves but this is going to be needed in any case

Stock valves are 33 mm intake / 30,5 mm exhaust. On E30 M42 models valve stems are 7 mm, on later E36 M42 engines stems are 6 mm and hence lighter. S42 used 35 mm intakes and 32 mm exhausts. I have photos of ports and combustion chamber but I'm not sure how to post them.

3. There seems to be quite a few documented harmonic balancer failures and subsoquent crank breakages when you try to push the engine past 7200 Rpm for some reason, not sure why?? there are aftermarket items available though

That is internet rumour. That information has been widely circulated and it has become accepted "thruth" but during my 3 years of research, I haven't encountered a single instance where anything like that has happened. I have revved my engine regularly to 7500 without ill effects, so far, that is.

4. the standard flywheel is a dual mass unit and not very well suited to race application but i think the M20 flywheel fits, maybe that will suit better or an aftermarket one if funds allow

Flywheel is 12,6 kg dual mass unit on M42 cars that were equipped with air conditioning from factory, all others (and I think all E30's with M42) have 9,9 kg single mass unit which is also used on 8 valve M40 engine.

All in all, M42 is interesting engine in BMW range but sadly most people opt for larger and more powerful six cylinder engines. M42 has all forged internals aprt from pistons as stock and it can readily accept M3 3,0 and 3,2 liter engine pistons and very durable forged crankshafts from BMW M47 diesel engines. You can construct 199x and 205x cm3 engines quite easily without resorting to buy exotic custom parts.

[trickymex]

Thank you Boyracer,

You have given me some very good information there and dispelled some of the horror stories i have heard

I am in to minds about using the M42 engine now, the main reason I contemplated the M42 was for the potential cost savings over a rare and expensive S14 engine but after looking at the M42 im not so sure the costs are going to be all that different

You see, if i go this route i will be aiming for more than 250bhp, i would like to be touching nearer the S42's peak power but i wont hold my breath as my budget and knowledge are probably not up to the job

For this sort of power there is no question about head work, on the M42 i will have to farm this out and spend a fair amount of cash getting this to the best i can, the quality of the head work is where the advantage will be gained over the other competitors who are using such engines as Pug Mi16 engines, these are as far as im aware one of the best flowing heads supplied as standard by a manufacturer

The fact that the head has hydraulic lifters adds to the extra work needed to get this head competative and also i cannot seem to find any really wild race cams(maybe you can help with this?)


For the sort of power i am aiming for i am reluctant to put to much faith in any O/E crank, rod or piston, of course the rods and pistons will be changed for aftermarket forged items but for peice of mind i would bite the bullit and go with an aftermarket crank as well, but the problem with the M42 is once i get the engine up to the 2000cc capacity limit for this class i would end up with an engine that has had huge sums of money thrown at it but will have a rather dissaponting rod ratio when compared to a short stroke S14 engine


Now i feel that rather than chuck this sort of money at an engine that is limited by design why not spend a little more and put the same sort of parts in a S14 engine instead?

To summerise

To get the M42 competative I will need:

Huge porting job
Solid lifter conversion
Larger valves
Custom crank
Custom rods
Custom pistons

And to get the S14 to an equally competative state I will need:

Milder porting job in comparison to the M42
The S14 has 38mm inlets and 33mm exhaust valves as standard
Custom crank
Custom rods
Custom pistons

But what i gain with the S14 over the M42 is a better bore to stroke ratio and a better rod ratio plus many proven cam profiles to choose from and many other aftermarket parts that i will not have to get custom made like i will on the M42

All in all i think the S14 will be easier to tune to the levels i want and its much more proven for this sort of thing, the M42 is going to be more of an experiment with unproven results, if it was a road car then i would go the M42 route but because its for a race car and i want to be competative i think it may be best to go for the proven method and be done with it

Im not sold on either engine yet and to be totally honest im not even 100% sure i will be going for a BMW either, what i am trying to do is investigate what car would be best for me and at the moemnt it looks like an E30 with either an S14 or M42 engine

Regards

Ricky