bmwe21.net forums

Spent the morning at the rolling road.

Had the car set up there when i first got it.
316 1.8 - twin dellorto 40's - 105 bhp at the wheels @ 5000 rpm

After mods
316 with ported 1.8i head, twin 40's, matched inlet and exhausts, electric fan - 130bhp at the wheels @ 5000rpm

25bhp increase, on the same dyno, with same tester.
Result!! cost me £250 total including new head, bolts, gaskets, etc and lots of dremmel time.
Happy with my results as its the first head ive worked on.

Next stage is to lighten the flywheel to get the power down a bit quicker.
Anyone got any tips/experience of doing this.

Rob :O)

wow! that is a result! well done!

That is very impressive! I have a 2.0 with big valve e21,twin 40's and schrick 292 and i'm pretty sure i don't make that much hp. What jetting are you using?

Good work!

Thanks all.

Will check the jets when i next get chance and put them up.

Had a raspy noise and a cool back fire on overrun appear last night, that turned into a blowing manifold on the downpipe.
This was a new gasket from Euro or GSF i cant remember which.
Closer inspection tonight revealed tha gasket had delamlaminated and had completely disintegrated - after 100 miles max.

Wont be using one if thise again - just hope the head gasket i put in was of better quality.

Good result there mate. My 2.0 with high comp pistons and a 284 cam gives me 160 estimated at the flywheel - but it's a small valve head as there was a crack in my big valve head. If anything goes pop I know what to do next, although the head has been ported and flowbenched and was flowing more than the bigger valve head did - allegedly!

Thanks.

My large valve head has been ported out quite a lot, and matched to the inlet.

As mentioned i think my next route will be to start lightening things.
Has anybody on had any experience with lightening flywheels on the M10's?

What is standard flywheel weight?
Any tips as to how much to bring it down by for general fast road use?

It will never see the track, i just want to be able to get to 3-4K rpm a bit quicker, it revs well above 3500 but just takes a bit of time to get there in the low gears. I have a very experienced flywheel engineer, just wondering what to expect.

Also what diff ratio am i likely to have? 3.91? What else will fit, i would quite like a better cruising 5th currently 70mph is about 3k. would like it a little lower if poss without ruining the rest of the gearing.

Ready for the weekend!!!
Rob

316 have 3.91, I think 320 6 cyls have 3.64 and then 323i have 3.45.

Correct me if I'm wrong. Impressive results by the way, and everyone should at least get out on track once!

So will either a 320 or a 323 one fit.

Somebody must of swapped these before - what gives a good combination with a 5 speed.

Thanks
Rob

hi mate.

well done on that result, to say its your first time porting a head as well. wouldnt mind learning to do that myself one day.

if your wondering about diffs, yeah if its from an e21 it will fit. what you need to do is be careful about your ratios you dont wanna lose all that decent power by killing it with an overly long ratio.

put your gearbox ratios and wheel size etc in to the below calculator (LINK) your final drive is obviously your diff ratio. This will then work out what your engine speed should be in any given gear and calculate your MPH

http://www.unixnerd.demon.co.uk/revs.html

its a bit cumbersome this calculator so if it starts annoying let me know what your email addy is ill send you a better one thats excel spreadsheet based so you can see it all at a glance.

Nice numbers. My 2.0 only dyno'd 114 hp at the wheels even after we installed the quad throttle bodies and 304 cam! That's a massive improvement over stock. Most people factor about 25% for losses through the drivetrain, so you're looking at over 160 hp at the flywheel!

If your doing 70mph at 3000 rpm, I'd stick with it. That's pretty comfortable cruising for a 4 cylidner. If you've got standard tyre diamters, you should be doing about 66 mph at 3000. Be thankful you haven't got a 4 speed! My e12 is on the rev limiter at 6500 rpm at 110 mph. Serioulsy though, if you change for the taller ratio, you'll hate the way it accelerates (or doesn't accelerate!).

Cheers

yeah, the fitting a longer diff is always a trade off between speed vs accelaration..... unless youve got the torque to carry it off (doubtfull as your lacking the all important couple of cylinders) id stick with what youve got!

After all the comments ive been starting to doubt myself, but the needle was defo pointing to the 130 mark on the power read out, as rwhp. I didnt get a read out as my dynoman said "We are not number chasing power monkeys - im after smooth delivery and the correct exhaust gas figures" He confirmed the figures afterwards though, and said it had a lot more power at the top end than before.

I was also running on optimax which ive always doubted before, but after putting a tank of 95 in this week, there is a considerable difference.
Will have to start planning my fuel stops - Pottering Driving = 95....Funtimes = Optimax.

Im after fast acceleration so ill start by having the flywheel lightened balanced and the clutch face faced. See how i get on then.....next step may have to be general weight saving, but its not a track car so maybe i should keep the rear seats carpet etc.....hmmmmm????

Not sure if this is of any interest to any of you but the garage i tend to do my work out also do servicing, restoration, tuning, track day packages/rentals etc...www.dsmotorsport.co.uk Based in the midlands. Great bunch of lads ive known for years - i drove the caterham and the trackday golf to Croatia and back a few years ago, on a 3500miles 10 day road trip. Awesome fun

Rob.

If your engine is in and working fine (which it certainly is!)I'd leave the bottom end alone. Pulling the flywheel off and lightening it should really be done with a bottom end balance if you are doing things properly. I have a lightened flywheel on the slug which is a track car, for the road with the power you have it won't make that much difference. Just cost you money, possibly weaken the flywheel if not done completely right, could upset your bottom end balance, will cost you money and you'll get a dose of whileI'mdoingititis and rebuild the bottom end with new pistons etc - if you want to know how I know just ask my Wife who will tell you how large the bill was.

My 2p!

Jim

I wouldn't stress the numbers. Different dynos give different results, but you used the same one twice. So you got 20% more power no matter what the numbers are. 20% is fantastic.

I'd wait until you do the bottom end before worrying about the flywheel. Given your improvements so far, I see some high comp pistons in your future

Cheers