E30 Zone

I've found the thread on the old zone where some members had done this with great results, and the guy who did it submitted the guide, but is still doesn't seem to be done.

Has anyone done this? I've got a 325i TB that's got 1 pipe for the brake vacuum hoses, but the 320i TB has got 2 pipes running to it.
Also, I assume you need a 325i inlet trunk to fit the 325i TB too?

has anyone done the 325i throttle body upgrade on a jetronic car? i plan to but am yet to figure out the best way to deal will the different mess of hoses... are all 325i TB's the same?

i dont mean to hijack your thread simon, just seemed like a good opportunity to ask

Simon I'm your man.

Still running the 325i TB on my 320i.

Let me know your email and I'll send you the guide, yes you need a 325i inlet trunking.

Not entirely certain but think you can use a Y connector to connect the 2 servo pipes to the 1 vac pipe from the TB. The versions with 2 vac pipes (like mine) both pipes go o the same part of the trhottle body anyway.

There is a slight mod from my original guide but I'll include this.

It is a good mod even without a remap you'll notice a substantial difference in mid range torque and top end power.

Cheers,

Iain

Nice one Iain

PM sent.

Hi Iain
Any chance of a copy of your guide please?
PM sent with my e-mail address
Cheers
Iain S.

Ok, so can a 325i TB onto a jetronic 320i be done? Boots_Walker; Make sure you let me know if you manage it!

As I see it, the issues are:


Compensating for the fuel pressure; Easy enough; squish the FPR or get an adjustable one.


Making the thing fit! Quoting Ant (from the old forum)

early 320 can be done but Ian will need to mod your old unit for you dude, not available as an exchange itme coz its a Jetronic body, gains will still be as god mind

So is it actually going to be possible to make a Motronic TB fit? Ant was talking here about the zone BBTBs, so that's evidently an option... I was just after something quick / cheap!


Relevant threads are here:

http://com4.runboard.com/be30zoneforum. ... |offset=20

http://com4.runboard.com/be30zoneforum. ... |offset=10

http://www.e30zone.co.uk/modules.php?na ... pic&t=2998



SeamanStaines / MasterBates seem to think it can be done, but Ant seems to be saying otherwise... Sorry if I'm just getting the wrong end of the stick here; I'd normally just take what either of these guys said as gospel!

Um... help?!

Templ8e30 wrote:Simon I'm your man.

Still running the 325i TB on my 320i.

Let me know your email and I'll send you the guide, yes you need a 325i inlet trunking.

Not entirely certain but think you can use a Y connector to connect the 2 servo pipes to the 1 vac pipe from the TB. The versions with 2 vac pipes (like mine) both pipes go o the same part of the trhottle body anyway.

There is a slight mod from my original guide but I'll include this.

It is a good mod even without a remap you'll notice a substantial difference in mid range torque and top end power.

Cheers,

Iain

Could you send the guide to bobbaxtor@hotmail.com as well please?

It would be good to get the write-up into the Zone articles, poor Iain will spend all his free time sending emails otherwise ;)

Regarding the jetronic: the only thing i think i need to sort out is the vacuum pipes for the brake booster and the different intake trunk - shouldnt be a big deal, just need to actually get the thing bolted on and fix it all up. I'm running megasquirt so tuning isnt a problem

if i were still using jetronic i would consider fitting a 3 bar FPR from a 325i(i'm 95% certain the standard one is 2.5bar - i have a 3bar one just sitting here maybe i should just get off my arse and install it to see if it makes a difference), and tighten the AFM flap a bit to compensate for the extra fuel. perhaps even a 323i ecu would work - afaik the 320i and 323i used the same injectors etc... i tried a 320i ecu in my 323i and it ran fine

Emails sent guys

Cheers,

Iain T

The Motronic throttle body will bolt straight onto the LE Jetronic inlet manifold, once it's been suitably opened up with a dremel. The problem though is that generally, not many Motronic (i.e all 325i) throttle bodies have the small vacuum pipe take off for the distributor. The 320i manual has two, one for vacuum advance on the engine side of the throttle disc and vacuum retard on the airflow meter side. The latter you can do away with as the Automatics didn't have vacuum retard and neither did the later post '85 320i manuals.

Some say that you can do away with vacuum advance altogether but I don't agree 100%. Vacuum advance is there to advance the timing at part throttle openings and is primarily an economy/driveability aid. Anyone who knows stuff about old Minis will know the Cooper S had no vacuum advance because it was a competition engine designed to run on 100 octane fuel. The 1300 Marina didn't have one because the crank used to rumble like buggery on part throttle!

Two ways around this; drill out the vacuum take off lug on the 325i TB (you'll see it), or try running without vacuum advance and see what it drives like. You might be okay with the static timing advanced a couple of degrees and rely on the centrifugal advance to do it's thing.

The ECU's are the same. As for air flow meters, the 320i and 323i use the same unit so I'd leave it well alone - if it works with a 2.3 engine, it'll work with a 2 litre and bigger TB without alteration. More fuel pressure is a good idea, well, 0.5 bar anyway.

Also, because the throtte body used such a thin casting (2mm), you won't be able to fit a bigger disc into the standard 320i TB. The 325i TB is vastly bigger and the throttle disc is bigger than the 320i alloy casing!

As for the other pipes, you've got problems. The two TB water pipes go on the wrong side, you've got a big hole for the idle control valve and the 325i throttle lever is the wrong shape for the vacuum throttle damper. In all, it's going to be a complete PITA.
As your engine is getting a bit smokey anyway, fitting a standard 2.7 Eta bottom end and a set of valve stem seals would be a better idea......

Cheers SS; I'm doin nothing with it if it's gonna be that much hassle! Got a new engine to go in when I can pick it up from JonB's; cheaper than doing the stem seals! & then I'll have the old engine to potentially add to an ETA over the summer... Though I'm gonna want motronic on that so I'm not sure how much use my lump'll be!


The minor issue is the MOT that's imminant! Wish me luck

I have just twigged who SeamanStaines is.. Am i a dumbfuckwit or what

hmm, that does sound like a bit of a pain (dont know if it will stop me trying though ). perhaps there are more suitable units from jetronic m30's? i might just visit a few wreckers and check out TB's from different manufacturers and hope to find something good

The M30 ones are no good - the stud pattern is different and the throttle disc opens anti-clockwise.

The 325i TB can be fitted, but you will need the TB water pipes from the 325i, add a vacuum port on the TB for the distributor vacuum advance and cut/weld the throttle damper lever onto the 325i unit - or just fit the 320i throttle lever although you'll have to grind off one of the pivots and replace it with a 10mm nut and bolt with a suitable shank.

If you took the 325i throttle body off a scrapper with everything - all the hoses etc - it shouldn't be too hard really. The biggest problem you face is enlarging the inlet manifold hole from 56mm to 65mm and there isn't much room at the lower edge. You'll need to use a 325i TB paper gasket as a template.

As an illustration of how much bigger the 325i TB is, the outside diameter of the 320i TB is 2mm smaller than the 325i's throttle disc. It's a lot bigger!

yeah i just had a look in the ETK, m30 definitely no good

325i shouldnt be too much drama, think i'll just stick to that. with the vacuum advance pipe on the jetronic TB, is there any reason it couldnt just be relocated somewhere else? maybe a T fitting on the FPR vacuum line perhaps?

It needs to be in a certain place on the TB so that you get a vacuum on part throttle. If it's on the engine side of the throttle disc you'll get vacuum advance when the engine is on idle/overrun, if it's on the AFM side it'll be advancing (if at all) on wider throttle openings. I've looked at an old 325i TB (from an '86 car) and the undrilled vacuum port is right where the edge of the throttle disc sits.

On your 320i, it's easy to see which is vacuum advance and which is retard. With the engine idling, pull off one of the pipes to the distributor and suck on it - if the engine speed increases, it's the advance capsule. If it slows down, you've found the retard capsule - if it does nothing, the capsuled is buggered!
Once you've identified the position of the advance and retard vacuum pipes, just copy their position onto the 325i TB.

If you're in a warm climate, you could also get rid of the water heating pipes on the TB and just join them together.

Ziggy - let me know how you get on with the MOT! Can't believe it's been a year!

Can I just confirm what your all talking about please. You are on about the jet-tronic system, correct?

This doesn't apply to motronic on newer cars say 1989??

Cheers

Chrome bumper 320i cars up until E reg have got LE Jetronic. Plastic bumper 320i's from E reg have got Motronic - on Motronic 320i's, the 325i TB swap is pretty easy - just grind out the manifold and fit the TB - all the rest of the pipework is the same.

SeamanStaines wrote:Chrome bumper 320i cars up until E reg have got LE Jetronic. Plastic bumper 320i's from E reg have got Motronic - on Motronic 320i's, the 325i TB swap is pretty easy - just grind out the manifold and fit the TB - all the rest of the pipework is the same.

Thanks for confirming

had a quick look at my car yesterday - the vacuum advanced line looks to be very slightly on the AFM side of the throttle plate. worst case scenario i just need to drill a hole in the new tb for the vacuum advance.

now i just need to get me a throttle body. ETK show a couple of different part numbers, i dont know what the differences are so i'll just get whatever i can unless somebody knows better

Hello guys,is this guide still available or can i find it on here somewhere?
Thanks

Sure is, drop me an email templ8(at)hotmail.com and I'll email it back to you.

Whereabouts in the borders are you ?, I used to live in Carlisle until a few years ago.

Cheers,

Iain T

Ive emailed you,im about 5 miles east of peebles,approx 18 miles north of Hawick.

HI SS

Can you replace the inlet manifold on the early 320's with a 325 one?

That would save on the dremel work!

Q

Im probably talking total rubbish here,but i would guess that the 325 manifold is a bigger bore? therefore the effect would be lost as instead of putting more air through a smaller tube therefore gaining port velocity,you would lose the effect of the smaller diameter acceleration.

Ive probably just made myself look a total arse! (make a change then!not!!!)

With regard to what borderbmw wrote about the 325i inlet manifold (i/m) tracts having bigger bores, surely the 325i i/m won't match the 320i cylinder head ports? The difference in size/shape would create some turbulence of the air going into the cyl head which would be detrimental to performance. That's why I want to keep my 320i i/m when I do my 2.7 conversion!