A race bmw 316, m10, s14, m20, turbo, na, its been the lot!

[Pushrod King]

Re: a very powerfull and troublesome bmw 316

Well we have very similar cars, it all comes down to who has the better engine builder

[Graham]

Re: a very powerfull and troublesome bmw 316

a little more progress



i've pulled the diff out so i could change the ratio to suit the N/a engine


i was a little concerned as to the condition of the diff interals as i bought it from a scrap yard and have never even looked inside it, thankfully it was like nw inside, so i simply got on swapping the CWP the only new parts i used were a collapseable spacer and oil seal it was a 3.46, its now a 4.27 which is possibly slightly short, but my only other ratio is a 3.9 and i think that is likly to be a bit long so better to undergear than over as that will have less detrimental effect on performance

back under the car

[david_white]

Re: a very powerfull and troublesome bmw 316

Good work Graham, I've been removing my diff ready for its N/A ratio today too, except mines going off to a nice man called Tom for its rebuild and new LSD

[mk2stu]

Re: a very powerfull and troublesome bmw 316

looks cool will you and dw be in the same class then as ive not read this in abit im abit concerned about this back injurey happend tho

[Graham]

Re: a very powerfull and troublesome bmw 316

i'll be racing in the class above DW and AP, they are in class D which is upto 1600 16v or 20008v

im going in class c which is upto 2000 16v or 2500 8v

the almost if not all of my opposition will be fwd cars, theres a very quick 16v mk1 astra, some fast honda intergra's and numerous peugoet 205 and 306's that are all pretty dammed quick

[Graham]

Re: a very powerfull and troublesome bmw 316

after spending a while cutting holes in my head to throttle body adapter plate i decided i just wasnt happy with it, i just couldnt get the nice transistion from T/B to head i wanted and i know this engine really likes a good inlet, so i bit the bullet and ordered an inlet manifold



now i have nice manifold, but its got a bend in it, i know for a fact the bend will cost power around 10bhp, so i hatched a plan






i got a mate to cut it up and weld it back together without the bend




rather than carry on trying to adapt my existing throttle bodies i phoned emerald and ordered some, they gave me a very healthy discount

the bodies are an enorous 50mm, 48 would of probably been big enough, but oversizing t/bs doesnt have the same downsides as oversizing carbs it gives me a bit more tuning potiential and due to the slight offset in the inlet manifold the bigger size will give me a better straighter inlet tract into the bargin




lastly for the mo i also got my mate to add some mounting lugs to my rad and relocate and resize the inlet and outlet much simplfying connecting the cooling system

[david_white]

Re: a very powerfull and troublesome bmw 316

Nice one Graham, those TB's must look mahoosive

Rad looks good and as you say will now plumb in nicely with no messing about

[Graham]

Re: a very powerfull and troublesome bmw 316

a little more progress i got my head back from being line bored to suit the oversize cam journals and its had a healthy 0.100 skim to bump the compression upto 12.1,

so i set about finishing the porting ( or so i thought!)

the inlet manifold needed a hefty skim on both sides to make its faces flat again,



and an enorous amount of porting to open it out to match the 50mm T/Bs




with the manifold now being quite short matching it to the head was very easily done with it bolted to the head,

next i egerly put the head on the low bench, here a problem emerged, either the head isnt flowing as well as it should although it still streets ahead of linford, or the hoovers have lost some suction so i need to do some testing and find out which,

either way i have found that the inlet mainfold has absolutely no reduction on flow, which isnt suprising as its straight and a finishes with 50mm large ports, although i didnt take a picture i found attaching a 45mm ram pipe made no difference to low, not suprzing really when you consider the valve is 46mm



next i added the 50mm T/B, which to my suprise does reduce flow slightly, not a lot but it does all the same, its the sort of difference you get from lifting the valve an extra 0.050 when flow is nearly at its peak, this suggests in terms of absolute maximum power the 50mm T/B as a good choice, clearly it butterfly and spindle are the cause of the restriction as thers othing else in the T/B althoug you can close off the throttle by a good few degrees without any further loss of flow, which also suggests its rather too big if rallying type drivability is your goal

[mk2stu]

Re: a very powerfull and troublesome bmw 316

very interesting read as usual graham!

with the head work complete how much power and torgue do think ull be looking at now you have a air flow figure?

will you be mapping the engine ureself?only asking as you seem to be very knwolegable and pretty much up for anythink

[Graham]

Re: a very powerfull and troublesome bmw 316

dave walker at emerald will do the the mapping, thats one thing i wont attempt on a diy basis, its just not practical to do it yourself on a car that cannot be driven on the road, even then i dont think you can get anywhere near an engines full potiential without a well equipped dyno or rollers.

power, hmm dont like talking that up front, as the holy grail of most 8 valve engines is 100bhp per litre and this is a 2.5 i'd like to see 250bhp, although the head should make over 110bhp per litre on a full race 2.0 bottom end it will be hard pressd to do that on a 2.5, i'll be gutted if i dont end up with at least 230bhp and hope to break the 250 barrier, torque wise i should see somewhere near 200lbft

[mk2stu]

Re: a very powerfull and troublesome bmw 316

do no what you mean is abit gypo thrashin down a strip of dual carridgeway i cant see myself how you can have enough road to do the job correctly

supose the final output isnt the main thing aslong as the delivery is matched to how you drive thats the main thing i wouldve thought

[Graham]

Re: a very powerfull and troublesome bmw 316

as its a circuit racing car, i want as much power as i can get but i dont need a huge spread of power, a power band 2,500- 3,000 wide will be enough so it wont matter if it wont pull the skin off a rice pudding below about 4,500, my last race atmo was only on song between 5500 and 8200,

i certainly wouldnt of bought 50mm T/Bs for anything other than an all out circuit car

[Graham]

Re: A racing bmw 316, hopefully the worlds most powerfull Atmo M10

work on my engines been slow of late, its had several trial builds especially the head which took a couple of goes to get the rocker geomtry right, then i had to deepen the valve cutouts in the pistons, those cut outs are now scarey deep but have to be because the cam gives a monster 0.230 valve lift on TDC overlap i've turned a std cam sprocket into a vernier so we can swing the timing on the rollers although last time we tried playing with the cam timing on a 316 cam it had no effect whether it will do so on the 336 cam is anyones guess, i've also modded the timing chain tensioner so it now has a "stop", on these engines the chain is tensioned hydralically with a light "helper"spring, this set up isnt great when you lift off ar 8k+ as the tensioner backs off

[carpmart]

Re: A racing bmw 316, hopefully the worlds most powerfull Atmo M10

Blimey - those valve cut outs are DEEP! How much steel is left below them?

[Doug@g19engineering]

Re: A racing bmw 316, hopefully the worlds most powerfull Atmo M10

Blimey - those valve cut outs are DEEP! How much steel is left below them?

None!

Apart from maybe the gudgeon pin