320/6 engine/tuning upgrades or m20b25 swap

[sleepy]

Hi,

I have been searching but haven't been able to find much on tuning options for the standard 320/6. It already has the weber on it...anyone know what (if any) hp increase I would be seeing with that?

So from what I can see its about making these engines less restrictive, what options are there for manifolds...are there any form other engines that offer increases that would fit?

Same with cams, any that would fit from another model?

Any suggestions welcome, I would like to see what I can get from this engine keeping the carb etc

Thanks

Chris

[e21-Mark]

Unless you are desperate to keep it as a 2 litre, just junk your engine and fit an e30 2.5 and injection. Actually, you could fit the 2.5 and re jet your Weber instead? You'll have 50 bhp more and getting your 2 litre to make that sort of power would be tough.

[sleepy]

That's what I'm trying to figure out just now, I had a e30 325 sport which I sold to a friend...he is now dropping in a port and polished m52 with us m3 cam and ss headers etc so the m20b25 is now available.

I have been thinking of taking the engine and swapping the carb over but was worried about what else may be required, would I need the 323 axle and e30 gear box? Anything else required for swapping the carb onto the b25 or is it as simple as swapping manifold over?

I am on a budget at the moment so that's why I was just thinking about keeping the 320/6 carb engine in it and maybe do some light tuning. Not looking to make major hp out of this engine or anything that would break the bank but was interested to know if there were any cheap upgrades for it such as manifolds and cams that could be swapped in cheap for gains...

[Duracel79]

If the complete 325i engine and loom is available, I'd go for it. including the Injection.

the 320/6 already has a fuel return line to the tank, so all you'll need is a fuel pump and filter wired in with the motronic loom spliced into the fuesbox.

Use your flywheel with the 325i clutch, your gearbox, prop and diff. Relocate the battery to the boot and you should be good to go.
Yours is manual gearbox right?

Ben

[sleepy]

Yes it's the 5 speed box I have. Ok that doesn't seem like it would be as much work as I thought but may still be too much labour charges I will have to check this out. What about the timing side, does the dizzy fit or would I have to get and e30 one?

What about the 320/6, what options are available for that?

[e21-Mark]

Just transplant everything over from the e30.

TBH you may as well junk the 2 litre.

[sleepy]

That's what I'm not wanting to do lol

Let's say the engine swap is last option, I would really like to keep the engine I have and would prefer to mod that one on a budget, do you guys know of what I can do to it?

[sleepy]

I appreciate the advice you are both giving by the way....just would like to see what is possible with stock engine rather than dropping the 2.5 in, I don't think I have saw a tuned 320/6 in any form

[e21-Mark]

I don't think I have saw a tuned 320/6 in any form

There probably a good reason for that.

Even a flowed head, lumpy cam and triple Weber would struggle to match a stock 2.5 and will cost a chunk of cash.

[sleepy]

I guess you are right, just something I thought would be cool to stick with what I have got. I'm not after the same hp as the m20b25 as I know that would be a money pit...I was hoping there might be a cam I could pick up cheap from say the like of the b25 or any other m20 that would make my current engine more sporty shall we say. I would have been happy if I could get around 140-50 out of the 320/6. I'm guessing then there are no such cams or exhaust manifolds that would give a little increase on a budget?

I am still considering the m20b25 swap but if I did go for that I would want to keep the carb, love that old school vibe and sound

[e21-Mark]

Just replace your engine with the 2.5 and have the carb re-jetted to suit. You could always get a cam from Newman or Cat but it'll add about £280 to the cost. A six branch isn't cheap either I'm afraid and pretty pointless on a stock engine anyway. I'd suggest a 2.5 with your carb will give the performance you're after anyway. You can always fit the injection later on, if you decide you want a bit more power.

[sleepy]

Ok so I have conceded....I'm now thinking it's got to be the m20 b25 I put in

So the plan would still be to drop the weber and manifold from the 320/6 on it, I think it will be good fun like this and if it is too expensive on the fuel I can covert to motronic later. Going by earlier advice it looks like I will be able to use my gearbox with e30 clutch, my prop and rear axle should be fine for this too. Few questions about the conversion then:

How would I tackle the distributor situation with this as my one is at bottom right of engine whilst the e30 one is at the front of the block?

With keeping the carb am I likely to see the 171hp or would it be a little lower?

What can be done for the exhaust, from what I read the exhaust ports on the m20b25 block are bigger than the ports on the 320/6 manifold and the e30 manifold won't clear things...what options are there here?

Any other issues or challenges I should be aware of trying this swap, the aim is to do it on the lowest budget possible as I have no income at the moment...I recently left my job so I can travel this year so money is tight

Any advice appreciated

[Eddie.]

I'm currently doing an M20B25 swap.

I can confirm the E30 manifolds won't work in an E21. So I went down the E21 6cyl manifold route.

I had read that the ports don't match, and I measured them yesterday. Ports on the M20B25 are about 31.7mm and the manifold ports measured around 30.1mm, so you're talking about roughly 1.6mm difference IMO, not something to worry too much about.

[sleepy]

That's great timely info, thanks mate...also saw your post about it the other day...don't know how I missed that lol

I'm popping by the bodyshop my friend with the e30 is getting his build done (m20b25 is now out of his) to get some quotes for sills both sides and a couple of other wee repairs and also to see how much he would take to swap the engine. Would love to do it myself if I decide to go for it but I don't have the tools/space at home to take something on like that.

Is there anyone on this forum that has the m20b25 with carbs on the forum?

[sleepy]

That's great timely info, thanks mate...also saw your post about it the other day...don't know how I missed that lol

I'm popping by the bodyshop my friend with the e30 is getting his build done (m20b25 is now out of his) to get some quotes for sills both sides and a couple of other wee repairs and also to see how much he would take to swap the engine. Would love to do it myself if I decide to go for it but I don't have the tools/space at home to take something on like that.

Is there anyone on this forum that has the m20b25 with carbs on the forum?