M20B20 cheap NA upgrade

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Coyote_ar
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Post Wed Apr 23, 2008 4:20 am

hi people, im planning on getting some extra punch from my 1984 320i.
so far i got a M20B20 with L-Jet.

im on a budget, so im trying to spend as little as possible.

for those who may not read my profile, im from argentina, not UK (LHD cars here :mad: ) . i just like this forum cause i found people are really nice and many very tech savy.

back into the issue. initially when i bought my car i thought turning it into a 323i. but ive been thinking that maybe i should go even bigger.

down here, most E30s are 318i, 320i and 325i. there are really few etas, so getting an ETA crank is almost impossible. dropping a B25 is EXTREMELY expensive. so its a nono. but we have plenty E21 323i, so i managed to get a crank really cheap.

luckily, good craftmanship here is cheap, so boring a B20 to 84mm shouldnt be a problem.

getting some custom forged pistons (i can get those cheaper than the original pistons winkeye . check www.iapel.com great and cheap custom made pistons. they ship worldwide ;) ) is no problem. i would keep 130mm rods i have now.

my questions would be, first of all, anyone sees any reason why that crank+piston size+rod setup should work?

regarding the fuel injection. i plan to eventually get rid of the L-Jet and put a MS-II there.
but initially i may not be able to do that. theres a chance that the l-jet will be able to work with such config? i mean, i dont expect high performance, but will it run at least?

if the answer is "no", changing the injectors for M30B35 injectors would help?

my concern is basically because this car is my daily driver, and theres no one with experience with MS-II down here. so installing it, and tuning it, may not be easy at all.
putting a motronic setup is not an opcion basically due to costs involved.

regards and thanks for any advice.
ed325i
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Post Wed Apr 23, 2008 7:55 pm

I fitted a 323 crank in a 325 block with 323/320 rods and 325 pistons and it didnt work.
So you would have to get custom pistons.

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Coyote_ar
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Post Wed Apr 23, 2008 9:04 pm

mmm why didnt you setup work?

325i is 75mm crank, with 135mm rods right?
and 323i crank is 76.5mm, so if you kept your original rods, i guess the pistons would hit the valves/head. but since you changed the rods for the 130mm wouldnt that solve the issue?

or is it that the skirt on the 325i pistons were hitting the crank?

i wasnt planning on using stock 325i pistons, but anyway your experience is quite usefull. thanks m8.
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Post Fri Apr 25, 2008 11:22 am

As machineing is available to you and cheap,why not go 2.8? Have a look though the forum,there are several threads with most of the information you will need.
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Post Fri Apr 25, 2008 5:32 pm

do the math..

crank stroke 1.6mm longer, rods 5mm shorter.. definately doesnt add up
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Coyote_ar
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Post Fri Apr 25, 2008 8:32 pm

daimlerman wrote:As machineing is available to you and cheap,why not go 2.8? Have a look though the forum,there are several threads with most of the information you will need.
i was tempted by that option, but the required crank is too expensive and hard to find. so i settled for 2.6.
Jhonno wrote:do the math..

crank stroke 1.6mm longer, rods 5mm shorter.. definately doesnt add up
my bad, now you mention it, i noticed he used the 130mm rods from the 323/320 instead of the 135mm rods from the 325.

ok, so i will take that into consideration when getting my custom pistons. so the skirt wont hit the crank/rods.

anyone knows if the L-Jet will be able to at least run the engine? maybe with bigger injectors for more fuel.
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Post Sat Apr 26, 2008 1:35 pm

So you are going with 84mm bore,323 crank in the why that Hartge (I think) used to before the 325 was introduced? See no reason why L-jet will not at least get the thing running,but it may be better with motronic and either a custum chip from Ant or a 325i chip.Good luck,keep us posted.
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Post Mon Apr 28, 2008 10:10 pm

thanks daimlerman.

actually im in argentina, so getting a full motronic setup is a tad expensive.

i was thinking maybe using the L-Jet + 535i injectors initially. Then switching to a MS-2 V3.0 for fuel+ignition. I dont feel that confident yet to be able to pull out the full displacement upgrade + MS-2 all in one move.

i will keep on investigating regarding the installation and tunning of the MS-2 while i get the money for the engine.

Another question i have. Lets suppose i get flat pistons. What compression ratio i will be getting from 76.5mm throw, with the 130mm rods? This will be with the 320/323 200 head.

i will be using this setup NA, with 96-98 octane fuel.
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Post Tue Apr 29, 2008 1:25 pm

Jhonno wrote:do the math..

crank stroke 1.6mm longer, rods 5mm shorter.. definately doesnt add up
:x

IT'S MATHS.

Furcking yoof.
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Post Tue Apr 29, 2008 3:07 pm

jaistanley wrote:
Jhonno wrote:do the math..

crank stroke 1.6mm longer, rods 5mm shorter.. definately doesnt add up
:x

IT'S MATHS.

Furcking yoof.
Pretty sure its Math..

Fecking old farts of today :roll:
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jaistanley
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Post Tue Apr 29, 2008 3:22 pm

It's fecking MATHS. Short for MathematicS.

God damn americanisms. Too many episodes of Barny and Friends have rotten your tiny student mind young man.
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Jhonno
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Post Tue Apr 29, 2008 3:30 pm

MathematicS is a title for many areas/subjects.. Plural.. Math is singular surely?!

Scrubs is my brain rot thanks :P
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jaistanley
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Post Tue Apr 29, 2008 4:21 pm

Can't be made singular. Like your pants cant.
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Jhonno
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Post Tue Apr 29, 2008 4:47 pm

Pfff.. Whatever.. I'm doing engineering, who cares about the finer points of English language?! Its all written in terms of x,y,z and the greek alphabet :P
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jaistanley
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Post Tue Apr 29, 2008 5:28 pm

Jhonno wrote:who cares about the finer points of English language?!
The English????

I did engineering too. :wink:
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Coyote_ar
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Post Wed Apr 30, 2008 12:08 am

i would say that math, singular, is correct. you can use math as in short for mathematical calculation or formula. and since jhonno was talking about 1 single calculus. singular should be the one.

that has nothing to do with the american use of math for mathematics, where jaistanley would be correct that the appropiate would be maths.

so leaving that behind, come on guys, i would really appreciate if we dont use this topic for literary chit chat. :wink: