Just curious as to what sort of power cranks, rods, pistons etc start going bang on stock A14's and A15's.

For any of you who have built a hot atmo motor or even a motor with forced induction did you use stock internals or did you go to forged pistons, strengthened rods etc?
Thanks Matty

yeah good question, specially after you read my latest post on a15ett

my motor is pretty stong i reckon, as it has been full blueprint and balance and reco'ed, i dont have forgies just standard new cast pistons etc. i would hope to think my motor is pretty strong.

"errol" should be able to shed some light on the subject built a couple of motors over ur time........ ?

i couldnt say much bout the stock internals of the Aseries, i have never blown one up or anything, gave my a12 a hard time, most of the time and it stood up to it...... a mate here in townsville used flog a A14 down the 1/4 here on huge NOS and it hacked it ofr ages, he used to tighten the head down after every run lol...

General rule of thumb for Datsuns is that the stock internal bits will handle twice the stock HP. So if an A14 makes around 68HP, it should be okay up until 136HP? Might go more, but you'd be looking at a real short life on the parts. Fortunately, most all Datto cranks and rods are forged. they can take a bit more than some others.

HTH

The major shortcoming of A Series (and Corollas and many others) are the pistons, which want to come apart above 7,000 RPM, give or take.
If you want big BHP, then the engine has to be capable of running up to 9,500+ .
The problem is that the inertia forces increase as with the fourth power of the RPM---that is, the forces trying to tear the engine apart @ 10K RPM is 16 times greater than at 5K RPM. And so it goes.
The only option is to use forged pistons at a cost of about AUD 1000 to 1400 a set, which only proves that big power costs BIG money.
If your Datto is a hobby, not a lifestyle, or you don't have that sort of dough, I suggest that the Hepolite pistons are worth a look. They certainly appear to be the strongest cast piston we've seen. We run our engine to 7500 sustained RPM and 8000 thro' the gears and haven't had a disaster ----YET. And, yeah, Ts & Ts is dead right, we get just over 130 BHP from a 1470cc A14

89mm where do you get your Hepolites? I have been able to get them since Reliance in SA went down!

My a12 motor is now good for 108-110 hp (with the new head) and im pretty sure the bottom ends standard (it was rebuilt just before i brought it and the guy didnt say it was anything tricky). I take it to 7500 - 8000 on the track and it hasnt caused any problems.

From all the people i've spoken to and read about this matter is that the bottom end crank is good for 200+ hp, it has 5 main bearings and is solid steel. The rods and pistons become more of a problem at high rpm (above 7500rpm) especially the A15 with its slightly stretched stroke.
Although you can strenthen standard rods a lot by polishing, shot peening, nitrating, and even baking them. I know someone with a racing 4AG toyota motor (220 hp)and thats all he has ever done to his rods was polish then then bake them in an oven for 400 deg celsius for 4 hours.
As for pistons, forgies are good because they are lighter (so less inertia, and reciprocating mass) and with different rings (less friction), equals less heat and fatigue at high rpm.

lata :)

RPM seems to be more of a problem than power output. My 1200 has been raced for the last ten years with the standard A12 GX bottom end , I buzz it to 7800 RPMs all day long. Now the race motor I had put out about 140 HP and ran to 9800 , the motor builder gave it 6 hours between rebuilds.
I used pit next to a GT-4 driver who ran a B210 , with the A14 they claimed the motor should go 10-12 hours but they always seemed to break something in the engine.
I seem to recall someone at Nissan Competition telling me keep the motor below 7200 and it would last forever.

Tom

120Ynutter.....

I would like to ask why do they have to bake the rods for 4 hours ?
Is it to ensure that the whole mass of the rod reaches the required 400