The CBR head is the only one i could find that will work. I did stop looking once i found that it would fit, so others could be out there.

Mind you you`d be doing well to find many heads that will out perform late model bike heads.

It would only be a great conversion for when competition rules stipulate the use of the original block. Otherwise it would be too hard to justfy the cost.

It would be much cheaper to do a complete engine conversion.

i really like Simons setup its gonna rock when he has time.

Non pollution and ready to breathe 150hp head is impressive.
Although simon is restricted in the u2ltr with the 1.7 multi-
plication factor for boosted improved prod cars, imagine this
head in an a15 with 79mm bores!

Also probably be easier conversion in sohc e13/15 or e16 but
they are pollution engines.

Not to be too much of a stick-in the mud but if it's 150 flywheel HP that is expected it seems like a lot of work. A well done GX head with 14:1 compression gets pretty close to that with minimal work. If it's 150 WHP it may be slightly out of reach of the GX head done really well.

In any event, if you are going after 150 to 200 flywheel HP you are probably going to need uprated rods, forged pistons, big cams, rocker modifications and a great deal of crankshaft work. This would all still be cheaper than the prospect of adapting a different cylinder head to the block and you would still need to dao all of it. I would say find a GX head and do all the proper work that you can think of and have a reliable package.

Surely an expensive project but when you factor rpm and reliability
once all the work is done the non-pushrod designs need more rebuilds.
Overall price with all the work done to a gx setup will be roughly
the same and even save money in the long run not to mention better hp.

Also the space on the graph as jmac points out is fatter and more
responsive on modern muti-valve designs.

I was always interested in the E15 engine compared to the A15
with the same factory 80hp the E15 is so much cleaner in response,
economical, quieter etc. I prefer the simplicity of pushrods but
when you compare it to a belt driven or chain driven multi-valve
of the same capacity you can certainly notice the improvement.

here is some idea on cost:


$600 head
$300 timing chain, sprockets and guides
$2500.dry sump sys.
$3000 min for Injection/0r $500 carbs.
$1400 Custom pistons
$1600 custom rods
$2500 fabrication and machining(if you can`t do it yourself)
$250 Electric water pump
$500 oil feed and drain lines
$400 Stud kit
$230 gaskets
-------
$13,280

Other bits would need to be done, flywheel, gearbox, radiator and exhaust and tailshaft too.

Dont want to put people off. Just telling it as it is.

I got this project happening as we speak, been on the go for about a year now, had alot of set back this year so hope to complete it late next year.

I can tell you what it has cost me to date and what my projected costs will be. (not to stir any feathers, just being a realist)

Head - $100 from wreckers with other useful parts.
Headwork (optional) - $1100, porting, valve work, flowing.
Duplex sprockets - $60
Camshafts - $500, custom 'one offs' from Wade.
Drysump set up - $2000 (about)
External water pump $200
Inlet manifold - $165
Throttle Bodies set up - $1100


Still to pay for,

ECU - Haven't decided on one yet (currently using Haltech)
Custom head gasket - $300
Head studs - $300
Coilpack - $400
Other stuff - $400, hoses, leads, etc.

I have a pretty good machine shop under my house so obviously I won't be paying for machining costs.

If I think of any other costs I will update.

The plan is to use my wet sleeve 1860cc bottom end with the twin cam head.

Pretty sure the GA option can be used with a fairly standard A-series bottom end.

Hi Lemonhead,
Its almost a pity mine is turbo. It would make engine perforance comparisons easier. It will be great to see them going.

The most thinking involved with the CBR head conversion was getting the cam drive to work. The standard bike crank sprocket was too small to work on the A series crank. I could get it on there, but the crank nose wouldnt have had enough strength to drive the oil pump! I ended up going with bigger sprockets and had to cut the front of the head for chain clearance. All sorted now.

Have you got your cam drive sorted?

Howdy sikyne,
Good to see some other people taking on interesting/difficult challanges,
I hope all works out for you, don't give up.

First obstacle for the GA head is that all 10 headbolts do not line up, 8 do but two need to be modified to work.

As far as driving the twin cam head is concerned I have gone for a new duplex drive sprocket of the crank, (it's worth noting here that I am not using a A-series crank and therefore had to adapt a drive sprocket to a different nose on the crank, and then machine up a new crank pulley to suit, if it was an A-series crank it would have been so much easier, ah well!)

For the driven reduction sprocket I am going for a triplex sprocket, machining one set of teeth off and and replacing that set of teeth with a sprocket of the same number teeth as the original camdrive sprocket to retain correct timing, therefore, driven duplex drive off the crank and the original simplex drive for the cams.

On the driven side of the duplex timing chain I am making a Auslon (bearing grade plastic) chain guide and the tension side I am going for a spring tension arrangement similar to the original GA set up, the original oil pressure chain tensioner is retained on the head for constant cam timing.

I am using a 3 stage dry sump pump with the tank in the back of the car and a external water pump controled by the ECU.

The timing case cover is a bit of a challange but nothing too hard.

I will be running 50/48/45 EFI Hardware TB's on a manifold I bought from South Africa, extractors will be similar to 'LZ' ones.

Like I say this will eventually be the head on my big 1860cc bottom end, I hope to make an honest 200hp reliable motor.

Just out of interest, I will be adapting a BMW Getrag 262 CR 1:1 fifth gearbox behind it and a original Nismo Works H190 rearend built for a Works Stanza.

I have alot of work to do next year.

need some e15 onto a15 info/pics
has it been done in a road car??
got a spare a15 and a e15t head laying around

Thanks, I wont be giving up.. Too much invested already!

I haven`t got any pics of the finished chain drive on the computer but here is one with the plates bolted to the front of the block and a separate bit on the head. It uses one Morse silent chain and standard bike tensioners that bolt to the plate you can see in the pic. The swinging guide is controlled by a standard CBR tensioner (which is a non oil, spring loaded ratchet type).


EDIT: You`re a bit lucky with the the GA head with nearly all the holes lining up! Will there be plenty of thread boss for the other two?
When using the CBR head, all the head studs have to be moved out 3mm. I had threaded cast iron inserts made to fill the original holes the had new holes drilled and taped in the deck to suit 1/2" ARP studs. I can use the standard MLS bike head gasket.

Ive made some vernier cam sprockets for the cams that look a bit cool. but i still need to make the timing case cover.
The pistons and rods are made and the crank has been lightend, offset ground and balanced.
Its nearly ready for assembly, but have too many other things on to finish it at the mo.