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E21 intake runner question

E3-3.0Si

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Hi all,

I’m a new member here and I’ll be posting an intro in the E3 section with some photos of my two 3.0Si cars (both are original RHD UK late model cars with L Jet).

My question is related to the E21 320i intake runner modification that I’ve read a lot about. My intent is to source an E28 535i M30B34 engine and rebuild it with some little upgrades, to be fitted to my ‘77 car. I want it to look ‘factory’ so I’ll be running it on the original L Jet injection system. I am more interested in torque and drivability than I am top end BHP. The car is already fitted with a 5 speed OD gearbox.

Having done some research, so far I have found a number of different part numbers for the 320i intake runners. Does anybody know which of these I should try to find, and what the difference is? Or is it a case that they are a series of superseded part numbers referring to the same part? This is what I’ve discovered so far:

11611264725
11611264723
11611265800

11611262614

Thanks all!
 

HB Chris

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sfdon would know but I think they are all the same. Some may have different bosses on the side to mount cables and such. I had a set where we ground down the bosses to have a smooth appearance.
 

sfdon

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11611265800 superceded 11611262614 and went next to the firewall (#4)
11611264725 went in at 1,2, and 3 position
11611264725 was an alternate for 2 position

As far as you are concerned- they will all work with a little bit of work.

 

E3-3.0Si

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Ok so I’ve searched and searched and searched and not found any E21 320i intake runners for sale. I have come across a few 2002tii items though, and this is where it gets confusing. The items I’ve found have a part number stamped on them that I can’t find anywhere. It reads 1257032, so clearly is a partial part number. I can’t find this on Real OEM.

Any ideas? Is the 2002tii intake runner suitable for this conversion, or do I need to find some E21 320i/E12 520i parts?

Thanks!
 

HB Chris

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Ok so I’ve searched and searched and searched and not found any E21 320i intake runners for sale. I have come across a few 2002tii items though, and this is where it gets confusing. The items I’ve found have a part number stamped on them that I can’t find anywhere. It reads 1257032, so clearly is a partial part number. I can’t find this on Real OEM.

Any ideas? Is the 2002tii intake runner suitable for this conversion, or do I need to find some E21 320i/E12 520i parts?

Thanks!
That is a casting number and they are quite useless.
 

HB Chris

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I do not, but Tii and e21 are different part number. Euro e12 used the Tii motor and at least several e12 models have the e21 runners.
 

E3-3.0Si

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I do not, but Tii and e21 are different part number. Euro e12 used the Tii motor and at least several e12 models have the e21 runners.
Yes this is where it gets confusing. I’d already committed to buy the Tii runners before I updated this thread, so I now need to find some E21 items.

I have an M90 engine from a 1981 E12 M535i which is going to be rebuilt before fitting to my E3. What I will do for the interest of the forum is a compare/contrast of the original runners against the Tii items and lastly the E21 items. It’ll be interesting to have some data to analyse around this!
 

sfdon

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I’ll share a recent Dyno using the big c-tubes

i Dyno every month and am always surprised at the hp difference with the long tubes vs short tubes.
keep in mind I bought every c-tube on eBay in the USA before I posted here.
;)

0A0908DF-413C-4A01-A8AE-0C2E85C8E3FC.jpeg
 

Bmachine

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Am I reading this right?.. around 20 more hp and 25 more ft/lb almost across the rpm range just by going to the longer tubes? That seems too good to be true.
 

sfdon

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That’s a beginning and a final tune on an engine with big ctubes
 
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