E30 M3’S

Steve,
it's entirely up to you how you run your car. As you can't really floor your car for a longer time over here, and that includes track day's (how long are you on full throttle on a traack, 20 sec?), it might not blow your engine up in a few weeks. If you dare it then that's your choice. i simply won't.
And since we are runnig lead free, you can't really judge by reading the colour of the plug.
And a 10.5 CR is low compression to you?

stevesingo wrote: Uwe, There is no difference in the running on my car between the 95 map with 95 fuel and the 98 map with 98 fuel. It rus exactly the same, The maps are conservative as standard and running 95 on the 98 map seems to bring the ignition timing closer to the optimum. I have pulled aplug after a sustained highspeed run and the colour seemed fine, indicating the cylinder tempretures are normal. I have some litreture at home regarding the relationship between C/R and Fuel octane and it makes interesting reading. It suggests that only high compression and F/I engines benefit from the higher octane. There are dyno tests that prove that some engines of more moderate C/R loose out when using higher octane fuel. It won't matter soon any way as I'm ordering the MOTEC Kit next week Steve

I can notice a difference between the two maps, it is quite subtle though. It's mainly the mid range that's improved.

As far as i understand it, the octane rating of the fuel makes no difference to the perfomance of an engine on its own. It merely allows you to advance the ingition or increase the comp ratio without detonation. And its these changes to the engine that give the power. Obviously with modern knock sensors allowing the engine to advance its own ignition, it can seem like its the fuel that makes the difference.

I have also heard that higher octane fuels can actually reduce the power of an engine, if used alone.

Simon325i sport wrote: I'm also looking for a new lower airbox section, as mine is broken, and I need the later type. Weird really as I was only checking on the ETK on the weekend, and it will not show the part number for the lower section on it's own, so Uwe, it looks like what you've heard is right!

I needed a new lower airbox after I discovered a PO had cut a great big hole in it. The p/n is 13.71.1.312.330.

Uwe - I still have the "modified" one waiting for when we next meet.

Cheers

 

Here is a photo of the old lower airbox........it wasn't a simple get the  drill out job. It is a bit of a mystery but the car is a lot better with the correct item fitted.

 

Evo2's do come with 46mm Throttles. Period.
The airhorns do have a second embossed ring casted if you want to cut them in length. I have the BMW press release printed in my folder.

you can look it up on s14motorsport.de in "ARCHIV"


TRY HERE

Edited by UweM3

The Evo 2 does use 46mm TB's, but they are made from the same casting that the 48 mm TB's are make from.

The standard 46 mm TB's use a smaller casting. You can get these machined to take 48 mm butterflies, but there isn't enough meat in the casting to get the throat area
(the part that bolts to the head)out to the same dimensions as the stock 48 mm TB's.

You can read about this on Gustave site.

Having been brought up on gold old carbs rather than injection there's one consideration that occurs to me that is often missed when folk get in to the nitty gritty re throttle bodies

Larger throttle bodies mean that the engine can breathe more air

But that extra air must flow faster because there's a limit to the amount of fuel a certain amount of air can carry at certain speeds

to get the benefit of better breathing capacity the engine must be able to rev faster to keep the speed of the incoming mixture high

that's just what you want for a high revving machine with a peaky power band but can be very boring on a road car

we all know that modern injection, engine management and so forth mean that these compromises can be engineered out to a certain extent, and I am the last one to doubt BMW's ability to get it right on these fabulous cars - but remember they are quite highly tuned as standard

the point i think it worth making is that the smaller throttle bodies aren't sub optimum unless you have specific tuning in mind

the comics we all read i think are responsible for making us all feel that like an airfix kit we should try to assemble all the right bits without thinking of the overall package

i would only worry about bigger throttle bodies if i was going to do motorsport...and that doesn't include trackdays (because the lack of an extra 25bhp wouldn't ruin my day since the clock isn't running)

then again if i had the choice between a later car and an early one i'd go for the later one for the bigger throttle bodies

have i just argued myself into a corner??

Edited by Jonners