E36 328i throttle body conversion....

[dimsum]

se6b said:

Its been nearly 24hrs now since I removed the restrictor and I have come to some conclusions; 1) The difference in noise when you plant your right foot is unbelievable. The only way I can describe it is that it now sounds like a touring car above 3500rpm. Theres a proper hard edged yet musical induction boom. It sounds like the engine has grown in capacity. 2) There is no difference whatsover in noise in normal relaxed driving. 3) It does feel like there is a bit more midrange and certainly top-end power. This could simply be down to the fact that it 'sounds more exciting'. Hard to be sure without figures. 4) That flat-spot at 2500rpm is still there 5) There are no problems with running at all. No stuttering at low revs. It drives exactly the same. The difference only becomes apparent above 3500rpm, and its a positive difference. 6) If you have a 328i you MUST throw your restrictor from the nearest cliff. THANKS GUYS!!!!

Well... After reading that, I think I may just go outand gove it a go right now!!!

P.s Took my "baby" in for some new rear tyres on Saturday. Got the first wheel off and... THE ALLOY HAD A 3 INCH CRACK IN IT!!!!. Oh Well.. out with the spare.. ANOTHER 3 INCK CRACK!!!

I have now had to ditch the standard (And gorgeous!)17" rims and replace with 18" MV EVO 2'S....

They are being fitted tomorrow.. Is this going to totally destroy the ride??

Oh well... Off to remove that restrictor thingy!!



>> Edited by dimsum on Monday 20th March 11:44

[adom]

se6b said:

Its been nearly 24hrs now since I removed the restrictor and I have come to some conclusions; 1) The difference in noise when you plant your right foot is unbelievable. The only way I can describe it is that it now sounds like a touring car above 3500rpm. Theres a proper hard edged yet musical induction boom. It sounds like the engine has grown in capacity. 2) There is no difference whatsover in noise in normal relaxed driving. 3) It does feel like there is a bit more midrange and certainly top-end power. This could simply be down to the fact that it 'sounds more exciting'. Hard to be sure without figures. 4) That flat-spot at 2500rpm is still there 5) There are no problems with running at all. No stuttering at low revs. It drives exactly the same. The difference only becomes apparent above 3500rpm, and its a positive difference. 6) If you have a 328i you MUST throw your restrictor from the nearest cliff. THANKS GUYS!!!!

I've got an e46 328 - given its the same engine and output, I presume this will also be applicable?

[BiggusLaddus]

adom said:

I've got an e46 328 - given its the same engine and output, I presume this will also be applicable?

not sure, it isn't exactly the same engine. the e46 model is twin vanos, e36 328 is single vanos.

with regards to chipping these cars, this can only be done on the early pre-facelft models. after the facelift (sometime in '96) the ecu's are OBDII and need to be remapped and not chipped.

Without spending thousands on forced induction, the main ways of getting more power out of a 328 are;

Big bore throttle bodies
Modified m50 inlet manifold
remap
US-spec m3 cams
cold air induction kit
new exhaust.

after that you can get more usable power from fitting underdriven pulleys and removing the viscous fan. there is a member on e36coupe.com who has an NA 328 that produced over 260bhp at its last dyno.

[adom]

Just taken the plastic bit out of the airbox and been for a quick testdrive in my e46. Well, I've been wanting to make the car a little louder since I got it, and that 5 mins spent pulling the airbox apart seems to have done a pretty good job. If there is any more power I can't tell, it would be that marginal, but a decent bassy note now accompanies every bootful of throttle over about 3k, and at least I can hear the engine properly when heel & toeing..... job's a good'un.

[turbo tim]

se6b said:

OK...spoke too soon. Now I've managed to get the airfilter out. Wow that was a tight fit!!! I've removed part of the intake, which just slid out the front. I'm guessing this is what you were referring to? It looks like a squashed cylindrical tube about six inches long?

Can you post some pics?

Cheers

[dimsum]

Well.. It took me 20 mins!!!

And I managed to lose one of the bolts that hold the airbox in place... But, I have also found a pleasing difference in the engine noise, and poss a small difference in pickup over 3500rpm.

I havn't been able to go for a decent drive today, but will have the chance tomorrow.

Not sure if its just the extra noise or if there actually are any real power gains..

Great noise though..

[se6b]

turbo tim said:

se6b said: OK...spoke too soon. Now I've managed to get the airfilter out. Wow that was a tight fit!!! I've removed part of the intake, which just slid out the front. I'm guessing this is what you were referring to? It looks like a squashed cylindrical tube about six inches long? Can you post some pics? Cheers

I'll try to post some pics tomorrow night. Good job I cleaned the engine bay on Sunday

[aggi]

Does the same apply to an E46? Sorry just read the whole thread!
hohohohohohoh I love simple engineering solutions!

>> Edited by aggi on Wednesday 22 March 22:00

[se6b]

aggi said:

Does the same apply to an E46? Sorry just read the whole thread! hohohohohohoh I love simple engineering solutions! >> Edited by aggi on Wednesday 22 March 22:00

According to adom's post apparently so. I did say I'd post pics but left my camera somewhere. Its a black plastic funnel about six inches long that sits in the opening mouth of the airbox intake. It has a notch in one end that clips it in place. Its probably easier to remove the whole airbox and attack it from underneath.

[adom]

se6b said:

aggi said: Does the same apply to an E46? Sorry just read the whole thread! hohohohohohoh I love simple engineering solutions! >> Edited by aggi on Wednesday 22 March 22:00 According to adom's post apparently so. I did say I'd post pics but left my camera somewhere. Its a black plastic funnel about six inches long that sits in the opening mouth of the airbox intake. It has a notch in one end that clips it in place. Its probably easier to remove the whole airbox and attack it from underneath.

Easy to do - just remove the top half of the airbox, then unclip and slide out the 3" diamater funnel-thing (looks like it has been squashed on one side - you'll know when you see it). Happy days.

[xm5er]

turbo tim said:

I'd interested to hear from anyone that has tried this - I've heard that by doing this, the balance of the airflow into the engine can be upset, and can cause the car to stutter when cruising along the motorway (i.e. engine at low revs/minimal effort)

Purely in the interests of science, I whipped out this "restrictor" from the airbox yesterday (took approx 60 secs as stated elswhere). Happily, whilst in the process I discovered an air leak on airbox to throttle body side (a trapped rubber seal that was sticking out) and fixed an uneven running problem that the car has had for a couple of months.

However, I seriously cant tell any difference so far, neither to the noise or the power output. I was however, highly amused to find that the car already has a cold air intake system as standard.

Now, I'm going to take a pic of this piece of plastic later and hope that some of PH's engine designers take a look (Marquis Rex?) because, to me, this thing looks rather over engineered and expensive to be a restrictor. An intake silencing baffle, possibly (though from inside the car i cant hear a difference, maybe I went clubbing too much when I was younger).

Quick question, will the car have to adapt to a little extra airflow (if thats the case) before offering up extra donkeys?

[Marquis_Rex]

xm5er said:

turbo tim said: I'd interested to hear from anyone that has tried this - I've heard that by doing this, the balance of the airflow into the engine can be upset, and can cause the car to stutter when cruising along the motorway (i.e. engine at low revs/minimal effort) Purely in the interests of science, I whipped out this "restrictor" from the airbox yesterday (took approx 60 secs as stated elswhere). Happily, whilst in the process I discovered an air leak on airbox to throttle body side (a trapped rubber seal that was sticking out) and fixed an uneven running problem that the car has had for a couple of months. However, I seriously cant tell any difference so far, neither to the noise or the power output. I was however, highly amused to find that the car already has a cold air intake system as standard. Now, I'm going to take a pic of this piece of plastic later and hope that some of PH's engine designers take a look (Marquis Rex?) because, to me, this thing looks rather over engineered and expensive to be a restrictor. An intake silencing baffle, possibly (though from inside the car i cant hear a difference, maybe I went clubbing too much when I was younger). Quick question, will the car have to adapt to a little extra airflow (if thats the case) before offering up extra donkeys?

It won't have to adapt to the extra airflow, the benefits should be instantaneous- it's like pushing your pedal more- or running at a higher load than WOT if you know what mean.

I would be interested to see a picture of this restrictor.
I read a paper on NVH by BMW and ALOT of effort was put into the structure and shape of the airbox of the M50 and M52 engined cars. The structure was designed to get rid of booms and break up standing waves in the intake system. The shape of this restrictor or the structure could be an extension of this philosophy. If it looks expensive and over engineered, it could also be because it's typical german and the German way, to engineer everything more expnsively (and not always neccessarily better!)
Still, some people are hard pushed to notice the difference, I know people who joined the NVH dept where I used to work, and at first they couldn't tell the difference of various configurations of intakes. It takes time.

[xm5er]

See what I mean, thats a complex moulding for a restrictor.

[dell.k]

If you have an E36 M52 328i

Standard airbox, amongst other things (like all of the inlet), is hugely restrictive on this car. This is why the M52 328 only has 1 BHP more than the 325 it replaced, 193BHP, and why it really struggles past 4,500rpm. It's strangled. Fact. End.

I initially removed the inlet baffle from the standard airbox & fitted a K&N panel filter. Cannot compare for flow with what is on there now.

It needs a decent heatshielded cold air induction kit such as below:

http://i3.photobucket.com/albums/y93/
http://i3.photobucket.com/albums/y93/
http://i3.photobucket.com/albums/y93/

Notice how the fuel rail cover does not sit on the manifold branches correctly as the manifold in my case is the modified M50 one which has much larger bores. The inlet ports on the head of the 328i are much larger than the standard branches of the standard manifold, starving the car at high RPM completely and restricting it to the 193BHP it unfortunatley starts of life with:

Please see:

www.bmw-m.net/techdata/m50vsm52.htm

This in conjunction with a larger bore throttle body (and in my case, larger bore ASC body), Supersprint cat-back exhaust and E-Map re-map gave my 1998 328i Sport this on Power Engineering's dyno in May 2005:

http://i3.photobucket.com/albums/y93/
http://i3.photobucket.com/albums/y93/

A not inconsiderable 244BHP with 227lb/ft torque (26.5% power increase)

Hope this helps a little and get's your '28's running as they should be.

>> Edited by dell.k on Friday 21st April 16:03

[turbo tim]

dell.k said:

Lots of useful stuff

Excellent - someone who appears to know quite a bit about this subject - welcome to PistonHeads

dell.k said:

I initially removed the inlet baffle from the standard airbox

Is that this chappy?

dell.k said:

& fitted a K&N panel filter.

...I've done this

dell.k said:

Cannot compare for flow with what is on there now.

Are you saying there’s a lot more power to be freed over and above the basic K&N panel?

dell.k said:

244BHP with 227lb/ft torque

I like the sound of that…..

[dtmpower]

Would this also work on a 2.8 Z3 ?

[dell.k]

Is that this chappy?


Yup.

Are you saying there’s a lot more power to be freed over and above the basic K&N panel?

Yes, the standard airbox is restrictive in it's design. A new panel filter will impove things a tiny bit, but hardly anything(airflow goes forwards and backwards and just take a look at the size of the inlet snorkel feeding the airbox from between the headlight and rad.

A cone filter has a much larger surface area which is not restrictive at all. However, because of heatsoak, it has to be shielded from the engine bay.

dell.k said:

244BHP with 227lb/ft torque

I like the sound of that…..
[/quote]

Me too. Did you have a look at the power curves? Torque is up hugley too. How many other N/A engines can you get around a 50BHP gain for under a grand?

>> Edited by dell.k on Sunday 23 April 11:21

[dell.k]

dtmpower said:

Would this also work on a 2.8 Z3 ?

Yes, as the engine is exactly the same.

[xm5er]

Maquis Rex, any professional comment on the baffle picture?

[Marquis_Rex]

xm5er said:

Maquis Rex, any professional comment on the baffle picture?

Ill try and give one, I'll also let a collegue of mine have a look too.
At the moment one of our guys has just handed in his notice and we're desperately trying to cover all the work!
Watch this space! {I don't have internet access at home yet!}