01. D/man [AUS]
02. B120Dat [AUS]
03. Dattoman_1000 (possibly 2 units) [AUS]
04. Lemonhead [AUS]
05. Ianey (plus uncle?) [AUS]
06. Ratdat_UK [UK]
07. kue1000
08. LTR [FIN]
09. Lampela [FIN]
10. Peltom

LTR,
I think you might like to do a little more in-depth research into the AY Crossflow engines before you get too deep into this project and make a fundamental error which will be costly to correct.

Here are some scans from an article that OLD TIMER Magazine ran back in February 2005. They show the very engine that I photographed in Japan, and they give a little bit of historical background on the story:




Notice ( if you look carefully ) the second set of spark plugs located underneath the area where the exhaust valve rocker shaft would be.

End-on view:




Oil pan on this particular engine is wet sump version.

And a picture of the heavily domed special race piston for the AY Crossflow:




( Above three images courtesy OLD TIMER Magazine ).

The magazine article reported that the FIRST version of the AY Crossflow was a 'Single Ignition' version, and this was soon modified to the SECOND 'Double Ignition' version - which was more efficient. As the FIA homologation papers show the FIRST version, it is possible that the JAF homologation papers ( covering domestic racing in Japan ) may also cover the SECOND version, or it was being used prior to proper homologation and the then-current homologation was going to be retrospectively updated ( which is not an unprecedented situation ).

I would have thought that the correct ( hemi ) pistons would be a REQUIREMENT for this layout, rather than an option. Anyone planning to use modified versions of pistons originally designed for the Counterflow A-series heads would be well advised to think again.........

The OLD TIMER article gave some period data sourced from Nissan's Omori race team ( which prepped the cars concerned ) that might be a fair guide as to what to expect. They said that the non-Crossflow A12 with twin 40PHH Mikuni-Solex carbs gave 100ps at 8000rpm.
The non-Crossflow race A12 with Lucas sliding throttle injection gave 150ps at 8500 rpm.
The AY Crossflow with Double Ignition and injection gave 160ps at 8800rpm.

Alan T.

Yes, I'm doing research all the time and learned something new allmost every day.

That dualspark revealed is a good thing that you mentioned. Thanks for that and pictures also.

However, the new one will be corrected in many way's that's for sure.

The sparkplug could be centered in the new one, only thing we need is to make it like toyota 2T for example.

But is this ok for everyone.

There many ways to shape the chamber nowadays and better the situation with that.
Knowledge has spread and that help's us by handling new way's to get around a problem.

But I'll get into this, hopefully some nice person will help us out on our journey.

S20 - are you saying that, those hemi/domed pistons are needed to run that head due to its unique spark plug setup etc?

And LTR - When you say:
Quote:

Corrected in many ways? thats a big claim. If S20 is saying you need that specific type of piston to run the dual spark setup, if you then "centered it in the new one" wouldn't that also require a piston redesign as a result?

If this is pulled off....it will be huge... the key will be getting everything done in bulk...if pistons are in fact required then we need to be thinking about getting 100+ made up etc...

Quote:My GX head is around 32cc from memory, but as we now know, the original AY12 engine used a domed piston, which negates the large chamber volume problem.

Custom forgings will solve this problem, but of course, they add to the overall cost & I don't know if we can get a run of castings made. The problem here is, .... what bore size, & what wrist pin size.

The 1200 engines that used this head had a bore size of 76mm or greater, but probably used the 17.5mm pin size & in all likelyhood, used the Titanium rods that were on offer in the 70's [at more than $950, ....... each, & that was when I priced them in the early 80's]

Even if cast pistons are used, the cost needs to be taken into account in the overall scheme of things.

Bring it on!

01. D/man [AUS]
02. B120Dat [AUS]
03. Dattoman_1000 (possibly 2 units) [AUS]
04. Lemonhead [AUS]
05. Ianey (plus uncle?) [AUS]
06. Ratdat_UK [UK]
07. kue1000
08. LTR [FIN]
09. Lampela [FIN]
10. Peltom

Thats the pics I wanted


Now I'm getting excited

I knew the domed piston would be a go with the 55.7cc chamber this head has
I have no issues with getting some custom pistons made when the time comes
Probably 77mm bore size for me
Pin size.... unsure yet
Didn't someone say the CA18 rod was the same length and we can get them in nice H beam forged. What pin size are they ?

Ok, the buying trip didn't go so well.. I did get the head for loan but he didn't wan't to sell it afterall.

He lets me/us use the head as a model for the new one though so the project is still going strong.

The head is now in modelling in the casting company and they make 3D CAD measurements/model from it for the casting model.

The guy had not found the rocker cover or the rockers, but the casting company told me that it is not a problem due to all the measure's they get from the head and all the picture's that I gave them from the engines with the head.

I also gave a old block for them that they take some measurements for correcting something they look from the pictures.

So now is the time to make up your mind and decide whether you are in or out.

I'll pay the modelling first myself, thats going to take about three weeks and then when everyones money is here I'll make the order for the casting itself.

All intrested can send their name, address, country, phone, e-mail, how many heads you want etc. to me for directly contacting you with further information and seeing that everyone gets what they ordered.

Topic: 11041-M0820 HEAD ORDER

To adress: ltr(aty)dnainternet.net

Recap the pricing again please
And what you get in the deal

Hey LTR - firstly thank you for all your work on this and your vision to see it through to completion.

I would suggest that you cast and machine only 1 head at this time and build it and get it running. Then you can demonstrate the completed item and ask people to pay.

You will have more people buy then - especially if you have worked out any little design kinks etc before running 40+ units.
The discount would still apply and you could make enough back on your machining to offset your up front costs.

Is this possible?