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i have an 2.0 engine if i change the throttle body and inlet manifold from an 2.5 what will i gain? and is there any diffrence in fitting.

BMWE30325 wrote:i have an 2.0 engine if i change the throttle body and inlet manifold from an 2.5 what will i gain? and is there any diffrence in fitting.

Spanner rash!

fit the manifold back on the 2.5 it came off and stick the whole thing in your bay .

i want to keep my 2.0 its low mileage and runs sweet just want to add a bit more Torque

BMWE30325 wrote:i want to keep my 2.0 its low mileage and runs sweet just want to add a bit more Torque

i've heard it is doable but how much gain you get fom it and what's involved i don't know .

have you chipped the ecu yet ?

magpie wrote:

BMWE30325 wrote:i want to keep my 2.0 its low mileage and runs sweet just want to add a bit more Torque

i've heard it is doable but how much gain you get fom it and what's involved i don't know .

have you chipped the ecu yet ?

no not yet i will be ordering the mlid chip from speedtouch soon

There are modest gains to had from fitting the 325i throttle body,but only to the 320i inlet,you need to open up the inlet's mouth to match the bigger throttle body.

The inlet manifold's differ between 320/325 to aid torque on the smaller engine,so swapping to the bigger manifold will not gain anything.

The 2ltr 6 pot is a short stroke motor,so it will rev freely to produce it's grunt toward the upper end of it's range.Only way,really,to gain low-down torque is to increase it's stroke....and therefore it's capacity...

Do all the hoses from the b20 fit fine and to the same places on a b25 TB? Is the ICV and TPS interchangeable between the two?

chip makes good difference. i just put in the wild chip in my 320 and its so much more responsive. also i havent seen any fuel consumption change ither.

daimlerman wrote:There are modest gains to had from fitting the 325i throttle body,but only to the 320i inlet,you need to open up the inlet's mouth to match the bigger throttle body.

The inlet manifold's differ between 320/325 to aid torque on the smaller engine,so swapping to the bigger manifold will not gain anything.

The 2ltr 6 pot is a short stroke motor,so it will rev freely to produce it's grunt toward the upper end of it's range.Only way,really,to gain low-down torque is to increase it's stroke....and therefore it's capacity...

Pm'd

I've had a 325 TB on my 320 for 3 years now. I widened out the 320 manifold as per an article on here. Don't know if the article made to Wiki or not - worth a try searching.

I also fitted a mild chip.

Can't say I've noticed much difference, just a bit more grunt mid range. The chip helped as well and fuel consumption is low to mid 20s around town and maybe as high as 28mpg on a run. The chip also helped smooth out the idle.

i've orderd the chip today i'll post up the results when fitted and tested

Any others who have done this mod?

I've thought about this for several years. There seems to be two schools of thought with one lot saying both throttle body and inlet from the B25 plus opening out the ports on the head to match. Others say that this will lose torque and the best way is to keep the existing inlet and just add the TB and match up the openings between the TB and inlet. Dunno who is right and tbh I ain't that bothered 'cause it's a very low priority job, which may or may never get done on my car.

A mild chip can make a difference - it just depends upon the condition of your engine. If it is already clapped out, expect little or no improvement, If the engine has been looked after and is in good condition, you will see some gains. It's well worth the small outlay and few minutes it takes to fit. You won't suddenly start burning off Focus STs , but overall drivability will be improved as will fuel consumption. A thorough service, mild chip and maybe injectors cleaned and refurbed are probably the most effective ways of squeezing more out of the engine. After that you're into diminishing returns.

Whatever you do, you're never going to turn your B20 into a racer. It wasn't designed to do that - it was to provide quiet, refined running for what was originally a small executive car. To get any serious poke out of it, you'd spend more than it would cost to fit an M52 engine, which is a logical upgrade. The B20 is a very strong, durable, smooth-running engine that is far less fragile than the B25, but it is a plodder albeit capable of some fairly brisk plodding. If you want much more than that and want to keep the car, a transplant is the only way forward.

DavieP: Interesting input! How is the b25 more fragile?

I wouldn't say the b25 is more fragile tbh, although I do agree with everything else in your post. The m20 2.0 and 2.5 are in essence the exact same engine appart from the obvious (longer stroke, bigger intake and throttle body ect ect...)

A good m20 2.5 will take a right hiding with decent performance to.

My view on the 2.5 throttle body on the 2.0 is that you will see very small gain if anything at all, the 2.0 is a short stroking block so if its noticable gains your after swapping a 2.5 in is the only way!! This can be done in a day easy.

When my car was originaly a 2.0 I thought about this mod but went for the 2.5 swap instead and the difference is tenfold!!! Even if you had a chip and 2.5 throttle body on a 2.0 and THEN swapped in a 2.5,,, the 2.5 would run away from "modded 2.0 and blow you away imo

The reason I suggested it is more fragile is that the same block is bored out more and the head is more prone to cracking and warping. That is not to say the B25 isn't a fine engine, it most certainly is, but it is not quite as resilient in the long term. However, if power and speed are your gods, then you must go for the B25 transplant at least.. No add-ons will put the B20 in the same ball park.

That said, finding a truly good, non-abused and thoroughly well-maintained B25 is not that easy nowadays and a rough or thrashed B25 is not a good substitute regardless of its potential former power. Trying to defend the B20 on this forum especially is a waste of time and in truth it is an old design that is well past its 'sell-by-date'. Having said that, a good one can be entertaining enough and is sufficiently rugged to withstand a good kicking provided your expectations and ego don't exceed its capabilities.

Very true ^

Wise words to which I agree tbh mate

"Even if you had a chip and 2.5 throttle body on a 2.0 and THEN swapped in a 2.5,,, the 2.5 would run away from "modded 2.0 and blow you away imo "

I fully agree.