Getting the most out of an M42...

[frogger]

To get the most (reliable) power out of an M42, what would be the best approach, without forced induction?

In this ascending order, I have:

1) Performnace Air Filter
2) Advance inlet (or exhaust) Cam a few degrees
3) Big Bore Throttle
4) Sports Exhaust
4) ECU Remap / Chip
5) Uprated Cams
6) Big head work - lightened pistons, fywheel etc.

I'm after useable, power that will not overstress the engine and stay reliable. Also, would be good to know what power people have got out of their M42's and what the theoretical max is if all of the above were done.

If anyone could put realistic BHP numbers next to each option?

[snoops]

I've heard that if you remove the heater plate it releases a few horses,

Kos on here had an iS which had modded airbox with panel filter, heater plate removed, lightened fly wheel and a remap, cant remember if there was anything else but it made 160 odd bhp.

[frogger]

Yeh - I read his remap thread.

Didn't know about the other stuff.

Cams are big dough. As is major head work.

I'm thinking, throttle, remap and maybe some kind of freeflow exhaust but I'm not into noise at all...

[agreen]

why not forced induction bmc carbon ait box????? i have a 318is to just got it so am very interested in this thread

[frogger]

Too much modding for my liking. I'm talking discreet and not after 100BHP+ turbos etc.

Just want to capitalise on all the minor tweaks that BMW ommitted. Don't want to win any prizes.

[anisotropy]

Chip and lightened flywheel seem to be the best for the money. I removed TB heater plate (because the hoses where perished) and really I don't believe it makes a difference. I believe some people put in electric fans to save a few horses.

[DIBLY]

How about removing that old barn door type AFM? and fitting MAF hot wire system. works a treat on my S14, had to get kit from States tho. SPLIT SEC was manufacturer.........

[Kedge]

I don't think the removal of the heater plate gives you more power, just maybe increases throttle response.

Te general theory with these is that the standard exhaust is as good as any and that goes for the air filter as well.

I've got a JB Racing flywheel coming over from the states and this is meant to give a massive gain due to it only being about a third of the weight of the standard flywheel.

[Ajay325]

If you want to increase power without forced induction use Kos's iS as a framewire. He removed the heater plate from the inlet manifold, added a k&n panel filter and drilled the airbox, had the car chipped and remapped a few times... result - 162bhp. Enough to keep with a sport and better around corners.

I read a good feature on the iS, and in particular Kos's iS in TBMW, they say that the iS was restricted to make sure the 325i sport was not put to shame. Interesting debate, but i definetely think the iS has huge potential.

[tomstickland]

I doubt those mods would give 160BHP.

[Dan318-is]

I doubt those mods would give 160BHP.

+1. Aftermarket cones just suck in hot air. No one has actually rolling roaded an i.S. with just a BBTB. Exhaust is not going to make any difference whatsoever. Flywheel will not give any engine output increase at all; will only make it respond better and accelerate faster as there is less oscillating mass.

[Kedge]

Totally agree with you Dan, there is a written report about air filters somewhere on the internet which certainly prooved that cone filters lost you power!

Following what has been said i don't think the M42 was that restricted since you can't get a better exhaust or manifold that flows anybetter, same goes for the airfilter. The only real gains that can be achieved without major internal work is from a remap (probably helped by a BBTB) as far as i can understand.

Regarding the flywheel i didn't mean it gave you more BHP, just like what Dan says more free revving which leads to better acceleration.

[Kos]

hello all,

just to confirm the mods to my old IS,

modded air box with K&N pannel filter
heater plate removed ( it is a restriction to the TB and in all honest probably keeps the inlet temprature slightly lower )
rear section re done in stainles with free flowing silencer, it was kinda loud as a result of this
and a re-map.

i belive the head had been skinned and this upped th C/R with again with the high octane optimax i was using will give an increae in power,

the only mod i didnt get to do was a BBTB.

all the mods only give small gains, air filters can give 2 HP somewhere but they are free flowing, same with the exhausts.

if you account 2 hp for air filer/air box 2hp for the heater plate removal, and 4 hp for the exhaust , none of which are unrealistic claims or expectations, its a total of 8 b hp,

standard figure of 137bhp goes up to 145bhp, and if it was runing on optimax it might get 2 more hp, that up to 147bhp, thats near enough what the rollers showed before the re map.

and it is fact the IS was restricted, so a gain of 10-15bhp on a remap is not unrealistic imo. i've seen many cars put out gains of between 10-15bhp over the years from ecu remaps. mine spent 4 housr pn the rollers and it did make 162 bhp.

i was doubful of the claims, but there are few people on this forum who drove it and whent out in it and can confirm that it was quick and would indeed give a 2.5 a hard time.

i only wish i changed the flywheel for the JB racing one, that imo is possibly the best mod you can do, yes it costs £400 plus fitting but consider what all the mods i did will cost. exhaust and remap come to about £400 if you get them at "trade" prices.

electric fan will make a few extra hp, nothing exciting but again it all adds up.

dan, my didnt have cone filter.
i'm sure you when out in my car, and i reall you said it certainly when better than yours and quite a few other regualrs from here on the forum when out in it and drove it who can say that it was fairly quick

there will always be doubter in this world, i am one of them and and very sceptical abouot claimed power figures but when it come to my own car i dont bull shit, i dont see the point. i prove it on the black top.

last year at the pod it put down a 16.2 1/4 mile, thats not far off the 2.5 sports i might add i had a bit of clutch slip at the time as well.

if i'm going to do it again, i'd like to go down the ITB route with cams and a JB fly wheel, whatch how it will make 180+bhp and rev like a motor bike.

but it all come down to budget, mine was built on a budget and proved its self

[Kedge]

Fingers crossed mine will be back together in time for santa pod (it will be tight) so a few of you will be able to see what difference the flywheel makes.

[Dan318-is]

Kos i didnt mean that yours had a cone filter, just busting the myth and trying to explain that they actually do fuck all no matter what you pay for them in my opinion.

Optimax etc will only make a difference if it is mapped for as standard e30s dont have knock sensors etc.

[Kos]

Kos i didnt mean that yours had a cone filter, just busting the myth and trying to explain that they actually do **** all no matter what you pay for them in my opinion.

Optimax etc will only make a difference if it is mapped for as standard e30s dont have knock sensors etc.

no worries, mine was run and mapped with optimax. it was the only feul that ever whent into it

[Dave_M3]

Was yours actually quicker or able to stay with a 325 Kos?

[Bob_S]

there is a crude test somehwere thats shows that the stock BMW panel filter is less restrictive than the K&N one.. hence why I always buy gen BMW filters

[Simon13]

2.1 conversion ala tim_s will make it shift

Hartge used to offer it as a conversion

[d6dph]

Ratch... I mean frogger won't be answering on this thread.

He has left the building

[Dave_M3]

M44 rods and crank would be a fairly cost effective mod too so would it if it was getting a remap?

Not quiet a 2.1 but every little helps

[tomstickland]

and it is fact the IS was restricted, so a gain of 10-15bhp on a remap is not unrealistic imo. i've seen many cars put out gains of between 10-15bhp over the years from ecu remaps. mine spent 4 housr pn the rollers and it did make 162 bhp.

What rpm did it make peak power at?

The most reliable way of estimating peak power is via top speed runs plus 0-60 or 1/4 mile times. By combining the results from these you can arrive at a reasonable estimate of true power.

It's best if you start with a standard car and measure the results, then modifiy vehicle, measure the new results and then assess the probable power increase. Personally I'd never trust most rolling roads for peak power estimates.

[Kos]

What rpm did it make peak power at?

The most reliable way of estimating peak power is via top speed runs plus 0-60 or 1/4 mile times. By combining the results from these you can arrive at a reasonable estimate of true power.

It's best if you start with a standard car and measure the results, then modifiy vehicle, measure the new results and then assess the probable power increase. Personally I'd never trust most rolling roads for peak power estimates.

cant recall at what rpm peak power was, but it was at a higher rpm than standard, i do know the rev limit was increased to 7000rpm

as far as your theory on estimating peak power with 1/4 mile runs an top speed runs, that will never be right, they are all varialbes which can be hugly affected with gearing and final drives. i've droped off 1/4 of second on averidge with a diff swop. maybe with a car that has a lot of track work eg cosworths and there is lots to compare your own to you can get a rough idea, but that brings up an other issue, driverand launch capability , but still its an estimate only.

rolling road are more accurate and give a better estimate than so called guess work, the perform and read better etc and adjust figure accordingly dependant on temps etc i'm no expert but they have impoved a hell of a lot in the last 10 years or so that i've ben around them.

the only accurate way is with an engine dyno, in cell run in a controlled environment.

rolling roads are the next best thing

[snoops]

Was yours actually quicker or able to stay with a 325 Kos?

^^^^

what diff was you running?

[Jon_Bmw]

Ratch... I mean frogger won't be answering on this thread.

He has left the building

I spotted him yesterday what name will he come back with tomorrow?

[Daf318is]

Now this is an interesting thread!

I'm in the middle of putting an M20 flywheel into my IS, it's been lightened but off the top of my head i dont know the weight. I am planning to get some more horses from this engine so i will watch this space with interest.

When I have finished- hopefully this weekend! i'll put some pictures and comments up.

Daf

[agreen]

YEH MATE IT IS GOOD THREAD THATS FOR SURE MY STANDARD 318IS NEEDS SOME HOTRSES ALTHIOUGH THERE IS REAL TIME TO BE TACKEN OF A LAP BY HANDELING BUT THATIS OFF TOPIC

[agreen]

SORRY FOR BAD SPELLING

[Kos]

Was yours actually quicker or able to stay with a 325 Kos?

^^^^

what diff was you running?

standard 4.1:1 diff and i would keep up with 2.5's up to about 70/80mph ( not sports they are a little quicker than a regular 2.5 due to sports box and diff ) then they would start pulling away. the gap was never more than 1 car length to that sport of speed . on a twisty back road in 2nd and 3rd gear driving i'd be on their bumpers.

[alan1272]

i've just got my 318is on the road and it feels slower than my 320i(!), admittedly it does have 40k more miles on it than my 320i but i though they should be able to blow the slow 6 pot into the weeds?

does anyone have a link to any guides to removing the heater plate?

[stuartgallafant]

you're wasting your time asking people about M42's on this forum. There's only a select few people that have time for them on here, myself included...

Get yourself over to m42club.com and read that. A good site, but its slow, as there is little users

Have fun

[Kos]

a good point from stu,

off topic stu, i hear on the grape vine you've given up on you project ?

[odbod]

Can't say I have any figures but mines running with similar mods, M20 Flywheel lightened, panel filter, drilled airbox, chip, electric fan, heater plate removed etc, all the cheap and basic mods (well the flywheel was more involved but I was swapping the engine anyway). I also have a 95-96 E36 M42 engine which has different cams and pistons which is suppposed to run with the disa system on the E36 but runs really well and is very smooth. The car is ver driveable and never fails to put a smile on my face and is quick enough to raise a few unsuspecting eyebrows.
Chassis mods also pay dividends, Z3 Rack bolts straight on and makes a huge difference and the Z3 quicshift makes the drive better, it's not all about speed the driving experience is also very important. Just put new wishbones and E36 M3 TCA bushes and new wheels and tyres (15" BBS black/silver with bridgestone RE040) Again these make more of a difference to the experience and fun of owning the car than alot of engine mods. There is a lot of info on M42club.com as stu says, but I have found a lot of help on here as well.

[stratos]

I cant see how removal of the heater plate makes any difference to the power. I have taken off the inlet hose and looked into the throttle body with butterflys fully open and I cant see any restriction in that area.
Or am I missing something ?

[tomstickland]

It prevents the inlet air from being heating which can make a small difference.

as far as your theory on estimating peak power with 1/4 mile runs an top speed runs, that will never be right, they are all varialbes which can be hugly affected with gearing and final drives. i've droped off 1/4 of second on averidge with a diff swop. maybe with a car that has a lot of track work eg cosworths and there is lots to compare your own to you can get a rough idea, but that brings up an other issue, driverand launch capability , but still its an estimate only.

rolling road are more accurate and give a better estimate than so called guess work, the perform and read better etc and adjust figure accordingly dependant on temps etc i'm no expert but they have impoved a hell of a lot in the last 10 years or so that i've ben around them.

It's not a theory, it's something I have done practically. I agree that there are many variables, but with suitable computer modelling you can build a picture of plausibility. You can combine various rolling road results with 0-60 and 1/4 mile times and come up with an estimate of true power. A decent physical model will allow the effects of diff ratio etc to be verified.

I started by making my model fit the published times. I also ran 1/4 miles and achieved thos sort of times.

I predicted the effect of lowering the final drive from 3.55 to 3.9 and found that this was about right on the 1/4 mile.

The process requires taking as much data as possible and seeing if fits in with expectations.

When I put my modified 2.0 8v Vauxhall engine onto twin 40 Dellortos and higher lift cams my top speed rose by at least 5mph. Tests done at various times and in various conditions all showed a similar increase in top speed.
This allowed me to draw conclusions about the probable power, up from a plausible 145BHP to somewhere just over 160BHP.

None of the methods alone are along totally reliable.
Most rolling roads estimate transmission losses based on the coast down curve , a method that is not accurate.

My experience has been that most rolling roads are optimistic. However, the accelerative capability depends on true horse power and because most people are using optimistic figures, a true 150BHP will give better performance than a true 145BHP with the owner thinking it's 180BHP.
You can take all the rolling road printouts in the world, but if you really want to see which car performs better, put two of them side by side and see what happens in a drag race. Assuming similar launches.