LY Engine Head Photos and Blog

[gav240z]

http://dattosankureiji.wordpress.com/2012/11/12/datsun-ly-goodness/#more-1606

 

I thought I'd share this, love the look of that engine head and triple carb set up. Has some other good photos if you look around also.

[d3c0y]

It's a shame this stuff is so rare compared to other marques. It would be cool if you could actually own some of this stuff and use it in racing.

[gav240z]

Totally agree mate, I just find this stuff so interesting. The thing is most people don't really know about this stuff with regard to the Nissan's they just see the 240z and assume they all came with the standard L-series engine and single cam heads.

 

I also really wish O.S Giken made the Twin Cam kit more available. I don't know why they don't really, surely there is enough L-GATA motors running about to meet supply / demand?

[d3c0y]

I don't think most people are prepared to build the motor to back it up though. No point putting a TC head on a stock bottom end.

Datsun owners are notorious tight asses, i bet if you sold them for an absolute bargain like $10k not many more people would have them. How many people you know with $10k 2 valve heads that equates to about a 300hp head fwiw.

[NZeder]

Given the LY was used in FIA competitions that is what we should be pushing for getting remade not a TC head that was not used in international competition.

[gav240z]

Given the LY was used in FIA competitions that is what we should be pushing for getting remade not a TC head that was not used in international competition.

 

How much of an advantage would this offer over the regular non-cross flow head? It's still limited to 2 values and SOHC. I notice that the angle of the carbs on the cross flow head looks like it would cause less turbulence as air enters the combustion chamber (less turns) but what other advantages are there? Port shape and positioning?

[NZeder]

Well think of the flow the good machine shops are getting from the non cross flow today vs back in the day. Now give the cross flow hemi heads aka LY flowed more then given the knowledge today I am sure more could be gained plus it would be period correct vs tc setups

[dat2kman]

Thats a road registered rally jobbie.

The built one for circuit race use only is at Zama.

Got some pics of it , somewhere.

[C.A.R.]

Les Collins had a LY in a couple of years ago for porting work.

When he was finished, his ported L series heads out flowed & out performed the LY by a decent margin...

 

While I'm sure Mr Thomas will have more accurate information (waits...)... I believe the main reason the 6cyl LY head was developed,

was to get the inlet tract away from the hot exhaust on the African Safari Zeds...?

Hence why the port design is not a big improvement on the LY...

[HS30-H]

Les Collins had a 4cyl LY in a couple of years ago for porting work.

When he was finished, his ported L series heads out flowed & out performed the LY by a decent margin...

 

No such thing as a 4-cyl LY Lurch. Sixes only. You sure it was an LY?

 

While I'm sure Mr Thomas will have more accurate information (waits...)... I believe the main reason the 6cyl LY head was developed,

was to get the inlet tract away from the hot exhaust on the African Safari Zeds...?

Hence why the port design is not a big improvement on the LY...

 

There's LYs and there's LYs though. Not all created equal. Early rally LY24, early circuit LY24, mid-term LY26 and later LY28 ( LY29 ) all quite different creatures. 

 

Technically, Nissan always said that the LY was aimed at use on the East African Safari Rally. But - somewhat ironically - it was never really used in anger on the Safari, whilst it was used in Works rally cars on several other events ( including the Southern Cross ).

 

The LY was used with great success in Japanese circuit racing. It was designed to be used with Nissan's ECGI system ( Electronic Control Gas Injection ) rather than carbs. It complied with rules that allowed an alternative head with the same number of valves and same number of cams as the 'stock' head to be used in certain racing classes, and was aimed squarely at Japanese endurance racing.

 

The car in the dattosankureiji blog ( originally 'TKS 33 SA 4079' ) was built for the 1973 RAC Rally, and its LY24 engine was running with the full Nissan ECGI injection system. It is now on carburettors, which is not ideal. Strange to see the car being described "as discovered" in one of the photo captions. It has never been 'lost'.

[C.A.R.]

No such thing as a 4-cyl LY Lurch. Sixes only. You sure it was an LY?

 

Brain fade on my part Alan - yes it was an 6cyl LY.

IIRC it had rather small ports...

[HS30-H]

Early LY ( 11042-E4622, homologated Sept. '73 ) had round inlet ports of 42mm diameter, and round exhaust ports of 40mm as-cast. They could be ported, of course. Later LYs had even bigger ports.

 

Would be interesting to know what head the comparison was being made with.

 

 

[d3c0y]

Yes i was thinking the same thing and of course it's not just about port diameter but transition to the back of the valve too.

 

 

Allan do you have any flow figures for LY heads?

[HS30-H]

No, I don't have any flow figures for the LY heads. I can't help thinking that stuff like that is too subjective to be all that useful anyway. You'd need to be comparing like-for-like for it to make any sense at all, and the only comparisons I have ever seen or heard were comparing a bone stock LY ( and which one? ) with a highly modified later stock production head, which doesn't make any sense to me whatsoever.

 

I think one of the things that gets forgotten with heads like the LY is that Nissan always kept an eye on driveability. These heads were not designed and engineered for dyno shootouts or drag racing, they were designed to be used in long distance competition under varying conditions. The fuel injection part of the equation helped a real lot with that, but more to the point they were usually just one component in a package that only really made sense as a whole car.