BMW K1200 bonnet clearance issues
Turbo Mini Forums

I've heard there is an issue with bonnet clearance on the k1200 head conversion, and im sure I've read of the actual height difference from the top of the block between A and K series heads.

However, I can't find this information anywhere after a search on here and the rest of the net. Could somebody put me back in the loop as to the common way around this problem and how much of an issue it is?

My thoughts were to drop the engine down a smidge by modding the subframe.

Cheers
Andy

You can put an auto frame moves it down about 1/2" IIRC or you could swop for fibre glass bonnet or cut the surports braces out of the steel bonnet.

or if your got some Cash have custom cover made.

I was consindering an auto frame but i may just modify the engine mounting spars on my current manual frame.

Does a fiberglass bonnet definitley clear it?

And does removing the reinforcing spars from the standard bonnet give enough clearance?

Edited by adcyork on 27th Nov, 2012.

I removed the bars on my turbo bonnet for intercooler hose clearence, and it kinked at the edges of the bonnet. Had to brace the parts that were removed

I was planning to overcome the chances of the steel creasing by reinforcing the folded over lips along the sides of the bonnet. I'd much rather drop the engine down a smidge though.

Who's done this and by how much?

i took the ribs out of my bonnet and its kept its shape fine its a heritage bonnet if that makes a difference

Fibreglass bonnet will clear/just kiss the top.

I'd drop the engine down, I cut my crossmembers out of the bonnet and it was very flimsy and the front corner of the cam end plate still rubbed.

If you use a fibreglass bonnet then you'd only need to drop it 10-15mm, but if you can go lower even better.

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1/4mile in 13.2sec @ 111 terminal on 15psi

several things can be done to get a standard bonnet to close without a bulge all of which need some sort of butchery to the bonnet cross member.

I have successfully used a standard bonnet with minimal modification to the cross memeber, but used the auto frame with spacers to suit to drop the engine about 1/2" (an old KAD trick)

also depends on what non aut subframe you have, since the post 1992 frames have the engine mounting holes moved forward about 1/2" meaning the cam cover is closer still to the bonnet.

Other tricks include canting the engine backwards a little (exhaust manifold dependant) and raising the back edge of the bonnet.