M42 Options - N/A - SuperCharged

[Neil_M]

Folks,

Hopefully you can help me here. I have read many threads on the m42 in the 318is, but hopefully you guys can confirm a few things for me.

For starters im looking at a 318is as a weekend / project car, which will likely turn into a track car.

I am looking for some clarification on the engine side of tuning.

I have read threads on some people going down the N/A route with internals from various BMWs. So I have made an effort, honest!

I see that Downing Atlanta make a supercharger kit for the engine. Does anyone use it or have any advice or opinions on it? I see it does use the standard ECU and is not intercooled or charged cooled. Should I see this as a problem? It offers around 200bhp.

I also see that Dbilas make an ITB kit for the car, it seems to offer an additional 15bhp. Likewise does anyone have any opinions on this kit?

Alternatively should I stay away from the more bolt on kits and go down the custom route. If I was going custom, it would be N/A with ITBs, standalone ECU etc etc. Just if anyone feels the two afore mentioned options would be better please say.

Perhaps it would be cheaper to throw in the S14 lump in? Assuming it is a straight forward swap.

Cheers in advance!
Neil

[appletree]

To start with the S14 lump swop is abit hard as the manifold is designed for a LHD car so its a case of getting a manifold made up at £Â£Ã‚£ plus the cost of all the recon of the engine


The IS m42 lump is good, the N/A route is a easy option if you were to say put cams in and then get a standalone management and run it alfa N (with out the AFM) this would free things up and would be a good start if you decided to force feed the lump in the futre. you culd probly get it up to 160 bhp ish

The downing atlanta kit from what ive heard is a well designed and made kit but as you said is abit crude with now proper management or cooling, you could fit the kit and then fit your own standalone ECU such as Emerald or megasquirt which would help the job along when i last looked they were running 187 bhp at 7-8 psi. Also the cost of importing the Kit would make the kit nealy £4500 , you could get Ant to build you a monster turbo set up for that!

The trottle bodys from diblas dont realy add that much more BHP for £Â£Ã‚£ and as far as i can see youd have to run standalone anyway. But they would finsh a N/A setup off nicely! also there would be the cost of importing them

I would have a good think about what sort of power you want and also the power deliver

[m-dtech]

jenvey also do direct to head throttle bodys

[Neil_M]

appletree, Thanks for the info and apologies for the late reply.

After further thoughts I do think that N/A is the way forward.

m-dtech, I will look into Jenvey as I have heard of them before.

Cheers folks.

[jkarran]

There's always the option of salvaged bike throttle bodies, just need to source or make a manifold to fit them. Much cheaper than aftermarket throttle ITB kits and at least as good.

jk

[MrDazzle]

There's always the option of salvaged bike throttle bodies, just need to source or make a manifold to fit them. Much cheaper than aftermarket throttle ITB kits and at least as good.

jk

This is what I plan to do one day...pretty far down the list of future mods, but I think it's the best option. They come with injector mounts, cable linkages etc. already included for a start, in a nice simple 4-body assembly.

I don't really want ITBs for the power increase, I want 'em to release the engine a bit. I love revvy engines, and especially ones that a free and 'zingy' with sharp throttle response. ITBs should help that along nicely.

[appletree]

Ive got a set and an adaptor plate that iám building up as a side project, not to fit to my car just for somethiong top do

[MrDazzle]

What are they from?

[MrDazzle]

Oh, and what are you going to do for the vacuum supply to the brakes?

[agreen]

what tb can you use from which bike ??? do you scrap the inlet manifold all together then more info on this plz pics if poss i am supper interested now i know there is a salvage option >!

[MrDazzle]

You can probably get away with TBs from any modern fuel injected 1000+cc bike 4cyl (i.e. any jap missile). Most bikes are gonna be revving up to anywhere between 12-15k, so even though an iS is 1795cc (i.e. just under 1.8 times bigger than a 1000cc bike), the much lower rev limit means the TBs from a 1 litre bike still give sufficient flow area.

You'll have to scrap the manifold all together I think.

You'll need to either have individual air filters on each TB (not good), one big air filter for all of them (again, not so good) or get a custom made plenum, inlet tract etc. so you get proper cold air.

You'll need to rig up something of the throttle cable. It shouldn't be too complicated, 'cause you'll already have 95% of the mechanism there from the bike. Just a quesiton of getting the pulley ratio right really.

Then you'll need something for the fueling. If you get TBs from an EFI bike (as opposed ot carbs obviously), you should already have a fuel injector system, complete with mounting/fuel supply rail, injectors etc present. Shouldn't be too difficult to mate this with the existing fuel supply.

The most expensive and difficult part with be getting it all set-up to run properly. You're talking fully mapable ECU and a day on a RR.

Finally you'll need to consider the vacuum supply for the brakes. I've never dealt with E30 brakes in detail, but someone in the inlet system upstream of the throttle plate, there'll be a take off to supply a vacuum for the brake servo.

I'll do it one day, but not for a while! Other things to sort first:p

I reckon the TB's from a Suzuki Hyabusa (1300cc) or a Kawasaki ZZR1400 would be best...simply because they are bigger bored bikes, so the TB spacing is likely to be more suited to an iS than a 1000cc bike. Could well be wrong though, will need to look into it.

[Dan318-is]

S50b30 bores are an almost exact match on my car, screw that bike wrongness!

[tim_s]

S50b30 bores are an almost exact match on my car, screw that bike wrongness!

yeah, that's cos i pissed about with them to make them fit (near) perfectly, dan. but yeah you're right you can get s50 ones to work well; they are massive though trumpets, plenum and tuning is the tricky stuff.

[MrDazzle]

S50b30 bores are an almost exact match on my car, screw that bike wrongness!

Wrongness? I should imagine that bike TBs are better made, and not to mention lighter, than BMW ones. Have you ever seen a modern bike engine? 170bhp from a 1 litre engine that only weighs 75kg (with clutch and gearbox) means some pretty high spec components...