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Can you name this Z Engine?


240ZR

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432policeengsm7ie.jpg

 

Found it Surfing, Wonder if it will bolt into a 240...... the name tells me it was a Police Engine, So i would assume it would of been a Japan only item, any one know HP? looks like 3 SU and DHOC.... Anyone done this swap? I assume its NA since Datsun/Nissan didnt start the Turbo crazy untill the 280s....

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It looks beautiful but the claims are it doesn't add enough performance to justify the cost. Only a couple of the heads made it state side in race cars for Bob Sharp and later on a 280ZX Japan rally car so I've read. They were destroyed or shipped out afterwards. The gains in performance were in the 4 to 6 % range. You could buy one for about $12,000 sometime back in the eighties from O.S. Giken of Japan.

 

Thats a completely different head. The S20 is different then the L series engine, my understanding has it that this head will not bolt onto an L series block.

 

The DOHC head for the L series was manufactured by OS Giken, as by the S20 was factory Nissan. There us an LY head though too, but I don't remember if that was for the S20 or not.

 

I'm sure if they want to, Tony D, H-S30H, and others could respond with a lot more valuable information. Or you could just look in the archives ;)

 

Mario

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4%~6% gain is the figure for crossflow SOHC head only.

 

The O.S. Giken head is a crossflow DOHC head which is completely different' date=' I think it was 20+% gain for NA engine.[/quote']

 

 

the 4-6% gain was compared to a fully race prepped sohc non cross flow Vs the os giken head, in similar fashion.

 

"how to modify your datsun"

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the 4-6% gain was compared to a fully race prepped sohc non cross flow Vs the os giken head, in similar fashion.

From How to Modify:

 

The optional two-valve, crossflow six-cylinder head is not available through Nissan Motorsports USA. The reason for this is it's not allowed in many racing classes. However, this isn't a major loss because the crossflow head will give "only" a 4-6% horsepower increase over a comparable two-valve, non-crossflow head. Consequently cost versus potential power increase doesn't make this a highly desireable head.

So it isn't the fully race prepped OS Giken they were talking about. There was another 2 valve crossflow L head that was released, and it made 4-6% more than a normal head. OS Giken would be worth a lot more than 4-6% IMO.

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That's the exact pic shown in the zhome site. The twin cams heads that fit on the L series motor were different, and HUGE money even in the 70's when they came out. (Upwards of $7K) And the power increase was minimal @ best.

The motor looks sweet, but unless your trying to replicate one of the few original cars I don't see the point. You can get a NA RB20 or 25DE block,and get a similar look for alot less money.

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That's the exact pic shown in the zhome site. The twin cams heads that fit on the L series motor were different' date=' and HUGE money even in the 70's when they came out. (Upwards of $7K) And the power increase was minimal @ best.

The motor looks sweet, but unless your trying to replicate one of the few original cars I don't see the point. You can get a NA RB20 or 25DE block,and get a similar look for alot less money.[/quote']

 

More tenth-hand inaccurate information.

 

We've been through most of this stuff what seems like endless times on this forum.

 

With regard to the Nissan 'S20' 24 valve DOHC:

It was a completely different engine series to Nissan's 'L-gata', and the head ( and all other major components ) won't interchange.

zhome.com seems to think that this engine in an S30-series Z body was 'most notable' for being used by the Japanese police force, which ignores most of its achievements and history.

 

With regard to the O.S.GIKEN TC24-B1 24 valve DOHC conversion for the Nissan L6:

Capacity was 2870cc, compression ratio 11.0:1, 9000rpm rev limit, peak power was 325ps @ 7400rpm ( all from OSG's original sales literature ).

It was created in the early 1980s - not the '70s.

 

With regard to the Nissan 'LY' Crossflow ( 12 valve SOHC ):

The Frank Honsowetz quote of "4-6% increase...." has always puzzled me. Sounds like more second or third hand information, and it's a little puzzling to imagine what was being compared to what.........

If I understand the text correctly, the stock unmodified LY was being compared to a race-prepped 'normal' L-series head ( which one? ). So they never tested a fully modified and optimised LY head and compared it to their best modified 'stock' L-series head? And the fact that the head was part of a package ( special crank, rods, pistons and many other parts ) does not seem to have been factored in to the comparison.

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With regard to the Nissan 'LY' Crossflow ( 12 valve SOHC ):

The Frank Honsowetz quote of "4-6% increase...." has always puzzled me. Sounds like more second or third hand information' date=' and it's a little puzzling to imagine [i']what[/i] was being compared to what.........

If I understand the text correctly, the stock unmodified LY was being compared to a race-prepped 'normal' L-series head ( which one? ). So they never tested a fully modified and optimised LY head and compared it to their best modified 'stock' L-series head? And the fact that the head was part of a package ( special crank, rods, pistons and many other parts ) does not seem to have been factored in to the comparison.

What I'm getting in the text is that they either tested stock against stock or modified against modified, hence the sentence: "However, this isn't a major loss because the crossflow head will give 'only' a 4-6% horsepower increase over a comparable two-valve, non-crossflow head." Comparable doesn't mean a modified head vs a stock head, at least not the way I read it. Frankly sounds like Honsowetz didn't do any testing, but he just took someone else's word for it, who may or may not have tested the heads against each other. The whole bit about the LY is only 2 paragraphs long, just like the 2 paragraph section on the OS Giken. Compared to his pages and pages on the "normal" L heads, I'd say he either consciously chose not to discuss the crossflow heads, or he just didn't know much about them.

 

Regardless, as Tim240z and Alan have pointed out this has been discussed ad infinitum here, and now we have another thread that just muddies the waters even more. One more useless thread with useless speculative answers to screw over the next guy attempting to use the search function.

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