17 replies to this topic

[Mini-Hazel-Nut]

Just a general question peeps. Has anyone ever tried fitting an alternative atop an A series block? If so which, how and what were the results? Thank you.

[hazpalmer14]

BMW k head has been done, fiat head has been done and I think cbr head possibly.

[Spider]

Here's a couple of Honda Headed engines (I didn't know Dave had posted these here !)

 

https://www.theminif...head-mini-engs/

 

[Mini-Hazel-Nut]

Thanks all. I once enquired about the BMW head job and they said that they can only do this one as and when heads become available. Plus they need your engine to modify and it`s expensive. As regards the Honda (motorcycle?) headed engines they were very impressive but the website link no longer works so that`s a dead end. Everyone who commented on that page was disappointed, including me. Carry on pushrods.....

[Spider]

,,,As regards the Honda (motorcycle?) headed engines they were very impressive but the website link no longer works so that`s a dead end.

 

What would you like to know ?
 

[IronmanG]

7 port?

[GraemeC]

Thanks all. I once enquired about the BMW head job and they said that they can only do this one as and when heads become available. Plus they need your engine to modify and it`s expensive. As regards the Honda (motorcycle?) headed engines they were very impressive but the website link no longer works so that`s a dead end. Everyone who commented on that page was disappointed, including me. Carry on pushrods.....

 

I'd be very surprised if any head not specifically designed for the A-series would fit without some modification needed to the engine which, in turn, make none of the head transplants cheap if you can't do that work yourself.

 

If you want 'bolt-on' then look at the various 7 port, 8 port and 16v options from the likes of MiniSpares, MiniSport, Specialist Components, KAD.....  And they will still be expensive (and no a simple bolt on)!

[Mini-Hazel-Nut]

 

,,,As regards the Honda (motorcycle?) headed engines they were very impressive but the website link no longer works so that`s a dead end.

 

What would you like to know ?

 

Hi, in a nutshell - everything. If it`s feasible outside a welll equipped workshop (which I don`t have) I`d like to have a go myself.

 

[Spider]

 

 

,,,As regards the Honda (motorcycle?) headed engines they were very impressive but the website link no longer works so that`s a dead end.

 

What would you like to know ?

 

Hi, in a nutshell - everything. If it`s feasible outside a welll equipped workshop (which I don`t have) I`d like to have a go myself.

 

 

This conversion, like all others that didn't come from an A Series Engine of specifically designed for it, is as Graeme mentioned, are a lot of work, including making many parts There's a fair bit of Mill and Turning work needed as well as some cast iron welding if it's a small bore block it's being fitted to.

All this could be farmed out, but it would cost. There's about 20 hrs machine work and if the welding is needed, that's not much at all, but the block will need to be pre and post heated. Once all the components are on the bench, then yes, only a reasonable home workshop would be needed to assemble it all.

 

A big advantage of the Honda CBR Head Conversion is that the Heads are still widely available and quite cheap. The BMW bikes weren't as popular as the Hondas in the first instance and the heads now are thin on the ground and command a fair price. A small 'thing' I feel is the way these heads fit up, the BMW Head needed some welding done on it, were as the Honda does not. I can't recall the finer detail of the BMW Conversion but I recall there was one point up where the timing belt runs is I feel a less than ideal arrangement when this conversion is done in that it is inviting oil leaks in this one area.

 

There are some other considerations here with either of these conversions, however, I don't know of any of these that have surfaced - yet. First is after fitting the Belt Drive for the Cams and the usual fan belt, they tend to end up hanging a fair way off the block in order to clear the water pump. This inevitably means there's little or no room left to fit a meaningful Harmonic Crank Damper. Off hand, all the conversions I've looked at run without one. Another big one is that the Bike Engines these Heads come from run in the reverse direction to the A Series (and most other engines). Unless you wanted to go to the expense of having custom cams made (and I think only SC Offer these for the BMW Head ?), you need to change the firing order of the engine from a balanced 1-3-4-2 to 1-2-4-3 which is theoretically is a very poor firing order in regards to Crankshaft Vibration, further exasperating the issue of not running with a Damper, which I strongly suspect will lead to short Crankshaft life. The few of these conversions I know of, some while have been done for a while, all only have relatively low mileage on them, so it would be nice to have a handle on long term.

 

If you are seriously contemplating one of these conversions, there's a few firms who offer kits, though, as you've found, they all need you to supply the Head and a Block.

 

I do have a Honda Headed 1100, in bits, more or less ready to assemble, in the workshop gathering dust. I did this for a friend, but he's had a change of direction with his project. It's not currently on my radar to do anything with it, though, I would like to complete it at some point.

 

Dave Rosenthal, the guy who video I linked up above, is a close friend of mine. He's well out of the Mini scene now days, but I have worked with Dave on a few of these Honda Headed conversions, as well as a few other mad projects. He's one clever bloke who's had several life times of experience and he taught me a lot. I feel a get debt of gratitude to Dave.

[Mini-Hazel-Nut]

Oh dear, all that sounds beyond me. I`ve no workshop, very limited tools and just the great outdoors to do it all in. I once fitted a seven port head to a 1275 GT with twin Webers and after rolling road tuning it produced no power increase worth talking of and  gave a top speed of 94 mph, not worth the expense.

[DeadSquare]

BMW k head has been done, fiat head has been done and I think cbr head possibly.

Which Fiat engine ?

       and

what is a"cbr"

[timmy850]

I’ve heard of the Fiat “Fire” engine being used (although it’s not a performance engine)
https://www.ausmini....php?f=5&t=86071

And the CBR head comes from a Honda CBR motorbike
https://www.ausmini....php?f=8&t=67881

[DeadSquare]

I’ve heard of the Fiat “Fire” engine being used (although it’s not a performance engine)
https://www.ausmini....php?f=5&t=86071

And the CBR head comes from a Honda CBR motorbike
https://www.ausmini....php?f=8&t=67881

Thank you.

[Mini Manannán]

Does anyone know which CBR engine it is?  There's been about a dozen versions of CBR600s...

[timmy850]

That particular guy said CBR600 F3 or F4