325 throttle body now fitted

[e30-320i]

i,ve seen alot of posts saying that to put a 325 throttle body on a 320 engine you have to match it to the intake manifold could any one tell me if there's any reason i can't change both the tb and inlet over as i have both laying around.
i know you'll all say i should put the whole engine in but if i was going to do that i'd just buy a 325

any advice would be appreciated

[dazleeds]

the port sizes on a 325 inlet are bigger therefore you cant straight fit it to a 320i

you have to grind out the opening on the inlet manifold to match up with the 325i tb if you look in tech section theres a full guide on how to
good luck hope this helps cheers Daz leeds

[Wilson]

the port sizes on a 325 inlet are bigger therefore you cant straight fit it to a 320i

you have to grind out the opening on the inlet manifold to match up with the 325i tb if you look in tech section theres a full guide on how to
good luck hope this helps cheers Daz leeds

Daz, read the post again mate.... I think thats what he's saying.. he's prepared to grind out the inlet manifold to match, but as he has got a 325i inlet to hand for no cost, why not just put that on, hence they will be matched anyhow, without any grinding. Will this work, or is there more work involved????

[Widge]

This will work but may, I dunno really, make it run rough as I think the inlet ports on the 320 head are smaller than the ones on the 325 so there would be a lip. Of corse enlarging them would be the first step to porting your head

[MONSPORT42]

There's an article in the current Total BMW about fitting 325 TB to a 320 which covers all the manifold issues. I only glanced at it today in the newsagents.

[dazleeds]

thats what the first part of my answer was on about the 325 manifold has bigger ports so causes probs when mated to the head Daz


ps widge i now have twins and some more fiendish plans

[Widge]

Oh yeah, is the new one MOT'd? And are we going to put a monstorously large engine in it? Still keen on getting a breaker mate, after this week I'll just about be free for the summer so keep you're eyes peeled.

[dazleeds]

theres a 325 on here now 150 but it miles away
im gonna put my 323 engine in the 316 decided already mate that way it gets it used and will make it a nice ride too gotta use up some stuff man ive got too much sat here no space to move as u know

mite have a 530i coming but still not definate that would sort mine out and its got some nice dished bbs on too
come round when ya back and we can work on yorkshire e30 domination Daz

ps no test on 16 soon will be tho

[StuBeeDoo]

When I do mine (Cheers again Widge!), I'm going to stick with the '20 manifold. I suspect that the bigger runners in the '25 mani will cause gas velocity issues.
However, I'll read the mag article before I make up my mind.
Stuart.

[Widge]

Stuart if you change your mind give me a bell as I have a 325 manif here.
Mate if you're putting a new head on why don't you put a cam and take advantage of the 2.5 inlet runners size. Obviously you'd have to port the ports (:mad:)

[StuBeeDoo]

Stuart if you change your mind give me a bell as I have a 325 manif here.
Mate if you're putting a new head on why don't you put a cam and take advantage of the 2.5 inlet runners size. Obviously you'd have to port the ports (:mad:)

Thanks for the offer Dave. I'm gonna get TBMW tomorrow and see what conclusions they came to before I make a decision. It's going to be another month before I get the new head anyway.
Stuart.

[Wilson]

thats what the first part of my answer was on about the 325 manifold has bigger ports so causes probs when mated to the head Daz

Gotcha!!!!!!!!!!!!!!! So back on topic, If he put the 325 complete manifold on it will obviously match the 325 tb, but its not going to match the inlet ports on the cyl head... he would have to match the head to the inlet manifold, which is far far far more work, than just matching the 320 manifold to the 325 tb.

Conclusion.... pointless using complete inlet manifold from 325i!!!

[Widge]

Conclusion.... pointless using complete inlet manifold from 325i!!!

Not pointless, no. Just more work, but if you are going for horse power a very worthwhile mod for the larger bore.

[Wilson]

Widge, I get ya, worthwhile doing for the gain.... but pointless without enlarging the cyl head inlet ports

[Widge]

Update

325i manifold installed with stock injectors and fpr.

rought idle,
alot better throttle response and while driving better throttle response.

performance :
0-60 10.3
hp by gtech : 82kw (111hp)
what is blatanly obvious is that itԚ´s running either very rich or very lean,

IԚ´m thinking the later,
IԚ´ll install a 3.0fpr and adjust the afm for idle and part

update later

So probably yeah, but it's not as clean cut as all that. And as for enlargeing the ports, it wouldn't be that much of a job. No more involved than making the TB hole on th manifold bigger but you do have to do it 6 times.

[Wilson]

it wouldn't be that much of a job. No more involved than making the TB hole on th manifold bigger but you do have to do it 6 times.

but I wouldn't fancy grinding head out myself, sounds a little more scary than just grinding the inlet manifold!!!, is there that much to grind out? I'm sure I've heard somebody on here has done it or said it could be done with a file!!??

(BTW In case you were wondering why I'm so interested in the subject its cause I know E30-325i, its the 325i inlet of my old engine that he is using!!)

[Wilson]

There's an article in the current Total BMW about fitting 325 TB to a 320 which covers all the manifold issues. I only glanced at it today in the newsagents.

Just bought total BMW, is a good article... Thanks

[Andy335Touring]

The head would need to come off and be stripped if you wanted to grind the head ports out due to the damage that the aly swarf could do to the engine if it got in to the engine which is very likly if you grind the ports with the head on.

[e30-320i]

thanks alot for the advice.if the weather is good i,ll be doing the job tomorrow following the artice in the mag it seems pretty simple i dont think even i could mess it up will post how i get on...

[StuBeeDoo]

Going to be a month or more before I can do mine!
Mind, I've now got the Z3M bush for my 3.64 diff. Just need to get the cover off and taken to my local garage for the old bush to be removed.

[e30-320i]

just finished changing the tb now i just gotta find a chip. Tt took about an hour and a half to grind out the intet but that was using crap stone bit and had to stick with the 320 bellows for now as couldn't find the 325 one (so if anyone has a spare )damn it was tight i would recommend using a 325 one. car is running good and seems to pull much better. we have a local test run (between a roundabout and bridge) and the car got 10mph faster to the bridge than before.i think this is quite an improvment for a grand total of Ԛ£0.....

......thanks to wilson

[StuBeeDoo]

the car got 10mph faster to the bridge than before.

This is what it's all about!! OK, so any dyno figures anyone comes up with are fine for comparative purposes, and it's brill that Gunni's going to the trouble of doing our experimenting for us. End of the day, what counts is how we individually perceive the improvement on our own "test tracks".

[schitz011]

exactly.

I'm not looking to kill the boys at the lights in their brand new M3's or SLK's just have a bit more oomph when I put my foot down.

I don't really drive much above 120/130 kph these days. Not since I slammed my old CTi into the back of some poor sod, so having a blinding top speed isn't an issue, but I would like to keep up with these foul compacts when we all pull away from the lights without having to rev the hell out of the engine.

I'm doing a full service this weekend, replacing all the usual stuff so i'll let you all know if any improvements come my way (the last service was 45000km ago... ) Also up here in JHB the air is really thin. Thinking about going to Cape Town at some point to see how it goes down there.. Even my mums old Polo went like a bomb at sea level. I guess the air at 6000 feet just doesn't cut it ;)

[Widge]

Schitz011 "Smoke me a kipper, I'll be back for breakfast"

Woof
Woof

[Simon]

Just thought I'd add to this topic, I had the 2.5 TB lying around so fitted it without boring the inlet manifold out, (ill get around to it sometime )
and it made a big difference just by doing this..should be even betted once the inlet is done too!!