bmwe21.net forums

Seeing as a few people seem to be either doing, or thinking of, M30 conversions I figured it might be useful to have a thread where we can deal with common problems and technical advice.

My first question, as there are bound to be a few, is what would be the best additional fan to add? I'm looking at a 17'' Kenlowe that sits between the rad and the front grills. I assumed there wouldn't be room between the rad and engine plus the OE fan is there anyway. Would 17'' be too much? It'll have its own thermostat but would I be better with just using a 14'' or something?

I am also trying to minimize heat soak to the cabin and am thinking of covering the bulkhead with heat reflective matting, ceramic or wrapping the manifold and shielding the air box. Is there anything else I could/should do to help reduce heat soak?

17 is too big. you want 14" Max.

i use a 12inch one and it needed a couple of brackets making.

I've been told it's too big before mate.

I've gone for the 14'' which was a fair bit cheaper too. The rad I have is a replica of the TWR original and is actually made using Land Rover tanks and a double core. Eventually, I will replace it with an alloy one as I think it'll help being more efficient.

I'm using an 13" kenlowe on the M50, mounted in front of the rad. It's mounted on a custom fab bar that the rad is also bolted too.


I don't think you would want much bigger TBH.

What sort of switch/thermostat are you running Rob?

I'm actually not at the moment, one of the things listed on my to do list! Handly the BMW rad I'm using has a themostat/switch hole on the side and I'll be getting one of these bad boys from cbsonline.co.uk

http://www.cbsonline.co.uk/fan-switch-9 ... 3530-p.asp

Though I'm not sure which bolt thread/temp to go for just yet.

The car when it had the M20B25 already had the fan fitted with an adjustable thermostat dial switch, with a long coil sensor which would wedge inside a hose and down into the rad. I didn't fancy refitting it, so I gave it to my mate who fitted it to his wartburg!

That fanswitch is too high for the M30.
I use a 85C one atm, comes in nice and early and does not allow the temp to build up too much.
I'll try to find the part number Mark as I can't get my hands on it atm.

Rav

Apparently it should be matched to the thermostat temp, of which I don't know either. Any guesses for the temp of a standard M50 thermostat?? What have you done Nas?

My stat is 80C iirc.

I'd be interested in knowing if the guys who've done the conversion are running the standard e21 diff, or have up-graded to a side-loading/e30 diff.










I'd imagine the standard e21 diff couldn't take too many abusive launches or hard corners w/ decent tires in the back......

My car runs an e21 diff but the difference is the way it's been mounted. It also has a larger oil capacity and better cooling with an Alpina rear cover with extended fins.

Not about M30s, but I have a few E21 diffs in stock for my M50 conversion. I'm going to see how I get on and if I eat all my diffs then I'll be converting an E30 subframe to sit on the E21 axle pins.

i used a thermostat switch on my rad from a friggin citreon. it kicks on at 85 and off at 90.. Nige told me the m50 likes to sit at 88 degrees.

most of what you guys sat about the m30 makes me think the m50 swap is about the same amount of a ball ache.

are we saying that cooling is an issue? well as you know, i have a custom rad,which i specified to be the biggest i could fit in the gap between the lights, to aid clearence. i am willing to bet the big 6 will have a problem with clearence as im sure its even longer? if the front of the engine is too close to the rad, you may find that it might come together if you slam on the brakes too hard?

i have the interesting problem of my rad being far too good at its job n not allowing the engine to warm up enough! this is also a problem i need to sort out the engine will chuck too much fuel in if its running too cool.

diffs...

this is a difficult one, i think im at the borderline of safe, ive done a few hard launches and some hard cornering and the quiafe seemed fine. You dont hear about many diffs breaking, but i think the halfshafts are going to be the weakest point in a e21 axle.

if i upgrade power significantly i would be inclined to use an e30 axle.

The rad that TWR built, and that mine is a copy of, is almost double the thickness of the standard 323i rad and the additional electric fan was there for traffic etc. On the move, the cooling was pretty much spot on. Obviously, this is just what I have been told though as I'm yet to drive it myself. I actually ordered a 14" Kenlowe this morning and it is supplied with an 'in water' sensor/thermostat as opposed to one that just goes in between the fins of the rad. It is also fully adjustable.

As far as I can tell, the problems with heat are one's of heat soak through the floor etc. This is why I'm going to coat or wrap the manifold along with heat reflective matting on the bulkhead/front floor. The head is really close to the bulkhead at maybe 10 or 15mm clearance iirc? Obviously the front panel is altered to fit the twin cored rad in place. TWR also built an alloy airbox in an effort to shield the air intake as much as possible. I am waiting for one of the previous keepers to find this and send it to me, or else I will have to fabricate one.

The only diff failures I have read about were because of excessive heat and that's why Alpina made the extended fins of the rear cover and why some applications gave the diff their own coolers/pumps. Again, this is just from stuff I have read. I do know that the sister car to mine was given a proper ragging, especially when Tom Walkinshaw was trying to beat Porsche 911 turbo 0-60 times! I know Hartge swappen to an e12 diff but afaik this was more about maintaining the same drive train, ratios etc as the engine donor cars. Murran probably gives his diff a harder time than any of us when he's drifting and I don't recall him constantly fitting diffs?

[quote="RetroBeemer"] I actually ordered a 14" Kenlowe this morning and it is supplied with an 'in water' sensor/thermostat as opposed to one that just goes in between the fins of the rad. It is also fully adjustable.
I know Hartge swappen to an e12 diff but afaik this was more about maintaining the same drive train, ratios etc as the engine donor cars. quote]

Hi mark... this is how my fan set is like .. with a "in water" sensor with an adjustable thermostat switch.. only problem i had was a Dry solder joint and the fan stoped working one day!!!! once sorted it was 100% fine..had it set to kick in at just under halfway and it would hold all day long at just under half way ,as for the rad mine is the same size as a 323i but twice the depth..
As for the diff i had the e12 lsd diff fitted and the dogleg gearbox fitted from the same car.. first is crap... way way way to short.. so i treat it as a four speed... 2nd, 3rd, 4th, 5th...#

Heat soak is an issue in mine especally when its a warm day!!!!! mind you i drove it through out winter every day 4+ years ago and that was a fun/scary learning curve..
only things that really blew me away when racing around was a white RS500(NMS) on the A40(very fast!!) and a ZX10 bike( one wheel till 100mph)..... also a knob in a SL55 although he started to under take on the hard shoulder.( i gave up)..