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Ocallen

Throttle body differences.

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Changing the throttle body on my 523i manual. I’m getting an enlarged one made up but on eBay I see a variety of throttle bodies that are described as coming off early 523s manufactured by different makers. 

Presumably BMW in their wisdom didn’t design a variety of different types to go onto the same cars to do the same job?

in the realoem list the one described for my year of car is ending in 414 but that rarely comes up in the ones taken off same age 523s on eBay. Can anyone advise please?

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On 04/09/2021 at 18:31, Ocallen said:

Changing the throttle body on my 523i manual. I’m getting an enlarged one made up but on eBay I see a variety of throttle bodies that are described as coming off early 523s manufactured by different makers. 

Presumably BMW in their wisdom didn’t design a variety of different types to go onto the same cars to do the same job?

in the realoem list the one described for my year of car is ending in 414 but that rarely comes up in the ones taken off same age 523s on eBay. Can anyone advise please?

414 so you have a M52B25TU? 

 

Don't mess with the throttle body, it's already pretty darn good for the engine. If you want extra power you need to remove cats (if it's allowed in your area) and perhaps start thinking of a LWFW. I have the HD version from raceheads.com.au with a E34M5 clutch kit (I'll be installing a turbo kit someday in the future) and it has really waken up the car. If I hadn't turbo in the future plans, I'd have installed equal lenght headers with true duals, or S50 exhaust manifolds.

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But the 523i is known to be strangled by the 2.0 inlet and throttle body to keep it under the 2.8 which had 193 v 170 bhp. Earlier 2.5 made 192. 
 

the accepted mod for both 2.3 & 2.8 was the throttle body/ inlet and chip for about 25/30 bhp. 

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3 hours ago, duncan-uk said:

But the 523i is known to be strangled by the 2.0 inlet and throttle body to keep it under the 2.8 which had 193 v 170 bhp. Earlier 2.5 made 192. 
 

the accepted mod for both 2.3 & 2.8 was the throttle body/ inlet and chip for about 25/30 bhp. 

Duncan's, wasn't this a pre-TU recipe?

 

Edit: and I take you're referring to the M50 inlet manifold?

Edited by jicaino

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Has nobody had to change their throttle body for whatever reason and come across the several choices of manufacturers basically offering an item to do the same job?

Surely they have the same fitting? BMW wouldn’t have designed several variants of fitting.

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1 hour ago, Ocallen said:

Has nobody had to change their throttle body for whatever reason and come across the several choices of manufacturers basically offering an item to do the same job?

Surely they have the same fitting? BMW wouldn’t have designed several variants of fitting.

 

Parts are often superseded - if you look on realoem it often lists a number of variations saying "superseded by" or similar or it maybe batches from different suppliers.

 

I don't see a part from a same car and model year but different P/N being an issue?

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7 hours ago, jicaino said:

Duncan's, wasn't this a pre-TU recipe?

 

Edit: and I take you're referring to the M50 inlet manifold?

 

I can't fully remember but the power was 170bhp for whatever 523i / 323i if i recall correctly.

 

As such they would both be strangled down when the M50 made a free and easy 192bhp in the same capacity.

 

My memory says Germany has/ had power based insurance bands hence the 190ish figure for the 325/8is and i guess the common 286bhp from bigger BM's?

 

My point was cats and manifold (headers) and a turbo is quite dramatic where as the larger TB and manifold was bolt on to give a bit more pep.

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10 hours ago, duncan-uk said:

 

I can't fully remember but the power was 170bhp for whatever 523i / 323i if i recall correctly.

 

As such they would both be strangled down when the M50 made a free and easy 192bhp in the same capacity.

 

My memory says Germany has/ had power based insurance bands hence the 190ish figure for the 325/8is and i guess the common 286bhp from bigger BM's?

 

My point was cats and manifold (headers) and a turbo is quite dramatic where as the larger TB and manifold was bolt on to give a bit more pep.

 

Oh, I see.

You're referring to the M50 inlet manifold swap. Well, that's a thing for pre-TU cars. It creates a lot of side issues to address too, like correctly crosbreeding a CCV piping and dealing with the difference in the conceptions between those engines. While technically the same, the cylinder heads are different. The earlier 2.5 litre engines have a cyl head with smaller passages and a short larger runner in the inlet manifold. That sort of favors high RPM power band because of the cylinder filling characteristics of that setup, while hurting some the low end. The "newer" M52 single vanos have a cyl head with larger passages and a manifold with longer, slimmer runners, creating a ram air charge effect that helps a lot in the low end (added velocity has better cyl filling) while gradually "choking" the engine as you go past 4.5k rpm.

One has to consider that the same manifold was used for the M52 and the S50 with no changes to accomodate different displacements. That tells us that the key in power with those engines a) it's manipulable by valve events and B) has its weak side on the exhaust side of the equation.

Later cars with the double vanos (M52TU and M54) have a different manifold that acomodates a long, thin section at some RPM range and opens down another internal path creating a shorter, fatter runner configuration.

 

Installing a larger throttle body and not compensating for it in the maps leans out the mixture, lean mixtures are quite dangerous and the M52TU has a notable tendency to warp, crack heads, blow gaskets and strip block threads...

 

Also the idea of an engine being "choked down " by either throttle body or carburator it's ancient. An engine is essentially an air pump, it will pull a certain amount of cubic feet of air per minute, meter fuel and make it detonate. The only reason to add a bigger carb it's to add more fuel to it, but the velocity of the air drops as the opening gets wider.

 

Another factor to consider is that M50 had different cams (it was hotter cammed than the M52) in addition to a different cylinder head and manifold.

 

So to sum up:

  • Installing a M50 inlet manifold on a M52B25 opens up the HP numbers, while hurting the TQ numbers. Installing a M50 inlet on a M52B25TU would be very cmoplicated and I haven't heard or read about anybody achieveing it.
  • Installing a larger throttle body means you're altering the metering towards the lean side
  • old cats that are clogging up/partially clogged can eat up to 20% of your power (that's why I went catless)

I realize that low mount turbo isn't doable in a RHD car, so I agree with you, there it goes the "simple". A top mount arrangement is way more involved. Otherwise, low mount, small T3/4 and low boost on stock internals buys you around 50HP (more if you install an intercooler and tune it up) 

 

Places to achieve quick and easy gains are:

Exhaust

ASC secondary throttle body

LWFW

Mapping the MS41 if you have a single vanos can go a long way. Not so much in the TU

 

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I think we have a bit of thread drift, OP was asking about alternative standard bodies though i'm sure i read a post where a larger TB was being fitted.

 

Edit - i did in first post :rolleyes:

 

Question is can they use anything other than the 414 type.

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36 minutes ago, duncan-uk said:

I think we have a bit of thread drift, OP was asking about alternative standard bodies though i'm sure i read a post where a larger TB was being fitted.

 

Question is can they use anything other than the 414 type.

 

In my original response I kept it thread relevant. There's no power to be gained from a B25TU with a larger throttle body AFAIK

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22 hours ago, Steve van hool said:

I don't know if they differ, but early E39's had engine management electrics by Siemens, and later on by Bosch, that will include the throttle bodies. 

 

My phase one 523i (manuf. June '98) has Siemens electronics & is officially rated at 170PS (168 BHP)

I think that the 181 lbs/ft is a respectable figure for a 2.5L.

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The 2.5 in the e34 was 190 or so bhp.

The initial 2.5 in the e39 was 170 or so and the 2.8 was 190 or so.

The facelift 2.5 in the e39 was 190 or so. 

This was all controlled by BMW because of tax levels.

 

An early e39 2.5 can be achieving over 200 bhp with fairly simple inlet and outlet modifications. Going back 10 years or so it was a common modification and there was a guy on here and in various other places in the BMW forums who manufactured the kit to do it. Unfortunately he was taken seriously ill a couple of years ago and lost his battle. He was well respected I gather. 

 

In November 2008 Total BMW ran a monthly feature for six months or so on modifying their e39 523i and only by fitting different inlet and outlet modifications they achieved 214 bhp at the flywheel on a rolling road. Various companies were mentioned in the articles that could help here but again they’ve disappeared.

 

Unfortunately the journalist who wrote the article is no longer with the magazine and the present editor cannot help me.

 

So I’m not looking for something for the first time but something that existed 10 or so years ago.

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^ that's my recollection too, obviously the facelift gained more power as it became the M54 525i (rather than the M52 2.5 badged 23i) and because the 530i had 230bhp or so it could be unencumbered!

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