m20 2.5 big six conversion!

Post Tue Jan 16, 2007 11:42 pm

ahoy

anybody done the big six conversion using the afm and injectors ect out of the 535i as i have just bought the stuff to do it and would like to know if its any good so any info welcome.

Post Tue Jan 16, 2007 11:49 pm

Buster has done it, I now own the engine, and yes it is worth it!!

Post Tue Jan 16, 2007 11:49 pm

not heard of this?

is this using all the m30 kit on the m20 lump?

or a proper full conversion of m20 to m30?

Post Tue Jan 16, 2007 11:55 pm

Uprating M20 with 3.5 parts

Post Tue Jan 16, 2007 11:57 pm

wow. would have thought that the m20 could only draw in so much air, so it wouldnt benefit too much (i.e. injectors etc).

i did the 3.5 afm conversion ages ago, and it made a little difference.

Post Wed Jan 17, 2007 12:02 am

Mine has 3.5 AFM, injectors, BBTB, Schrick cam, FSE fuel regulator and superchip

Post Wed Jan 17, 2007 12:05 am

wildeian wrote:Buster has done it, I now own the engine, and yes it is worth it!!

whats the car like to drive with this done and is there anything i should know when doing it.

i got a 325i rail fitted with the 3.5 injectors and an fse boost valve

and the 3.5 afm with the 2.5 circut installed + induction kit

is there anything else i need?

wullie

Post Wed Jan 17, 2007 12:10 am

was the chip mapped to the kit installed? i can imagine some decent gains in this instance.

Post Wed Jan 17, 2007 12:13 am

Drives great!!

There is a guide on the net about this, but I can't find it at the moment. Buster would be the best person to speak to, or maybe Ant to get a chip for it. I'd say to get the full benefit you're gonna need a high lift cam and BBTB

Post Wed Jan 17, 2007 12:15 am

was the chip mapped to the kit installed?

Yes, I believe it was.

Post Wed Jan 17, 2007 11:36 am

Can you explain why you fitted bigger injectors and a larger AFM?

I had an M20 327 running standard M20 325i injectors. With the fuel pressure turned up slightly they supplied enough juice for 213bhp and 220lbft with no issues at all.

Surely if you fit a larger AFM you then have to get the AFM set up on a rolling road, and essentially the operator will wind the spring right back to meter the same amount as the standard 325i AFM, as after all that's the correct amount.

You can chip it / map it all you want but the engine can't magically become more efficient and consume more fuel and air.

335i injectors and AFMS are a pointless swap IMHO.

Post Wed Jan 17, 2007 11:39 am

Its controversial, but a properly mapped and adjusted m30 afm makes a little difference. the injectors etc, i don't understand how that bit could work. Maybe they are slighty more efficient at the rated pressure, or flow? no idea.

Post Wed Jan 17, 2007 11:45 am

I've never seen a proven gain from an M30 AFM.

I think any gain that is seen, would be due to people fitting the M30 AFM and then getting it set up. i.e. they are having the AFM optimsed to the car. Had they just popped on to the rolling road with their standard M20 AFM and had that optimised correctly they'd have probably found the same gain.

I had a race car set up on the rolling road and just moving the standard AFM one notch gained 7 bhp on a 1.6 blueprinted race engine [Peugeot XU lump] that only made 122bhp peak.

Post Wed Jan 17, 2007 11:49 am

i thought this as well. Someone ona forum did this. roll roaded both sides (before and after afm).

it made a "noticeable" difference after fitting other things like air filter etc.

When i fitted mine i don't think it made much difference really, but the thought was there!

Post Wed Jan 17, 2007 1:20 pm

it made a "noticeable" difference after fitting other things like air filter etc.

So by adding other external factors he rendered it a completely irrelevant test.

As I said, I'm pretty sure nobody has ever got a proven gain from fitting an AFM that's innapropriate for an engine.

Post Wed Jan 17, 2007 1:23 pm

no, these were already on there. it was pretty comprehensive. anyway i can't find it so its irrelevant now i suppose.

Post Wed Jan 17, 2007 1:45 pm

I agree with Ste. I suppose using the 335i injectors has merrits if you fit throttle position sensor, a cam phase sensor and run a fully sequential ignition setup where the injectors will have to flow larger ammounts in less time for the same A/F ratio.

If I were you I'd put the money you'll save not doing into a pot then go see Ant and have a megasquirt fitted and mapped. MUCH MUCH better than mucking around with the std stuff... You can ditch the AFM completely, even the distributor if you're feeling saucy!

Jai

Post Sat Jan 20, 2007 10:53 am

a larger AFM on a smaller engine will (when set up correctly) lose resolution and hence make the signal to the ECU less accurate. this has the potential to throw the setup marginall out across the whole rev range.

the airflow required by the engine will still be the same no matter what size meter you use to measure it.