a-12 is best race engine, or maybe im biased cause im forced to use it



check your PM D

don't want to hijack the tread too much, but the A14 has a much better rod to stroke ratio. which has a number desireable effects for a performance engine:
* it makes the engine more sensitive to cam timing changes (ie you will get better results from that big race cam)
* better mechanical efficiency at higher engine speeds, and
* less stress on reciprocating components at high engine speeds.

small capacity engines need revs to make good bhp, and the A14 should do that better and more reliably than an A15.

Spot on Harry, That sums the A14 up nicely.
The fact that it ends up square bore and stroke is the same as an L20B as well with the rod stroke advantage.

After I finish the A14 for B120Dat I am building up a special A14 based engine that I think will probably use the A13 race head and the 79mm forged slugs. Only prob is I will have to do a very special set of rods to handle the engine speed I want.

How come Steve Newing and others have used the a15 to become vitorious in the 2ltr and under class?? I now about the magic 1:1 stroke ratio (eg. as found on the supra engine superiority to the gtr in NA form) but Ive been told bu many the torque of a long stroke has been the reason the a15 has done so well with its lower rpm but more flexible midrange.
Does anyone know about the a bore larger than 79?? I heard there is an 80mm available on some later a15 vanetter engines?????
Also what valves can be used to get 40mm inlets instead of 39mm ????

Steve used the A14 block and A15 crank to cut down piston heights/weights.

"A14 Nissan engine with A15 crank bored to 78 mm (1568cc) Forged Pistons,
Nitrated crank, Race prepped rods ARP Rod bolts, Full engine balance, Nismo lifters, Nismo high volume oil pump, 82 Degree cam, High ported head with Nismo valve springs and stainless steel valves, Steel light weight flywheel with Nismo clutch p/plate and solid centre button clutch, hand made interference sand bent headers, Wolf3D Engine management system with twin DCOE 45mm throttle bodies and HEI Ignition. Produces 165HP @ 7500 rpm and 118 Ft lbs at 5800 RPM " These were Steve's specs for his engine.

Piston speed gets you at high RPM with the A15 crank. I have sonic tested 2 blocks ($120 each test) to see how far the A14 will go. 79mm is it so far, unless some magic block turns up

40 mm are custom made. in my engine.

hmmmmm
sounds alot like mine except mines 77mm bore and no Nismo components but similar.
Oh and DCOE's not EFI
I'd be happy with 160hp but I think I'd be pushing it.
I didn't realise there was a difference between A14 blocks.......or between A14 and A15

So for an optimized utltra high-rpm race engine, the A14 sounds good.

For a typical street engine, the rod-stroke ratio in the A14 isn't going to overcome the 7% displacement advantage of the A15. The A15 makes more torque primarily because it's bigger, not only because it has a longer stroke (a bigger bore engine with same stroke would also have more torque, all else being equal (cam, manifolds, exhaust, etc).

A more interesting debate is the A12 vs. A12A (slightly bigger bore, but nearly the same displacement).

if my micrometer is correct the only difference between the a-14 and a-15 is the stroke 79mm vs 82mm. on the street that will equal a slightly more tractable engine (read flatter torque curve) but if you live in the upper rpm range the rod strke ratio will cause more piston skirt wear.

my datsun guru friend says if yoy use the a-14 rods and pistons with .060 shaved off the pistons you will improve the ratio and raise the compression ratio. his b2ugly rally car with that configuration will rev instantly to 8000rpm and pulls like an L-motor all the way up

at the end of the day more cubes means more power means more speed. everything else being equal
olboy

The rods are the same on the a14 and a15 just the pistons are taller on a14 hence 60 thou off will be safe to the deck height limits with the 82mm stroke.
Anyone know anymore bout the j16 or j18 crank on the mexican, pakistan and indian engines ?? 84mm stroke??