I'm looking for a Vanette 4.8:1 diff, or diff centre, or just the gearset. I want to install in my H165 diff housing and weld it up for racing. Anybody got one ????

This will also happen if your bearings are worn. Particularly if you've given it a hard time or driven it on low oil. Hope its not but it is a possibility!!

Woody, sounds like I'm going to spend some quality time sucking in your exhaust fumes then!! You should get a really nice engine for $10g. Thats two-and-a-half times the price me and Mick paid for our race car, and we went halvies in that!

Errol made a post a long while ago stating that one of the two types of 240Z big end bolts from ARP fit A-series rods. I plan to use these on my next engine. To date, we've used standard rods with new genuine nissan rod bolts and have had no failure (touch-wood). I've largly attributed this to our dedication not to over-rev it. Anyway, it seems possible to use nissan bolts, but I think ARP's are stronger and provide cheap insurance against a nasty failure - thats just my thought.

Do you know how to do compression calculations ?? Static and dynamic?? What about overall piston height (piston to deck clearance)??

I'm sure you would learn alot about your engine if you did strip and measure it all. But if you don't want to do that, I think there is enough wisdom in this group to get away without stripping your engine.


D, about the big strokes, I'm sure you've done a lot of research and know what your talking about, but I'm viewing things from a different angle. I'm concerned only with keeping the total capacity below 1632cc (1600cc + 2%) that our class of racing will allow. Obviously that will be the same for Woody. Saying that, the ideal setup for circuit racing is the biggest possible bore with whatever stroke is required to stay just under this capacity. I'd happily de-stroke it if I could use a bore big enough, but sadly, I don't think its possible within the realms of reality and my budget.

Talking outside the rules of our class...
Power = volume of fuel/air mixture x efficiency
Volume of fuel/air mixture = capacity x rpm.
so, Power = capacity x rpm x effiency.
But RPM is goverened by the forces on the bottom end. As a rule of measure, most engineers use average piston speed. Eg, an A15 at 7000rpm has a average piston speed of 82mm x 7000rpm = 574,000 mm/min or 9.57m/s. Now if we stroke it to 85mm (a stroke increase of 3.7%) and use the same redline piston speed of 9.57m/s we now have a new redline of 6753rpm (a decrease of 3.7%). You can see that the volume of air/fuel mixture for both engines at redline is the same. So the only power increase feasible is due to increased efficiency or increased stress on the bottom end.

A much better method is to increase the bore size. Std stroke, so same 7000 redline rpm. But increased piston area will result in increased air/fuel volume consumed, which in turn produces more power. A secondary benefit is the bigger bore will allow bigger valves which is a major bottle neck. When comparing the A15 with modern engines, compare bore/stroke ratios and also bear in mind that the two-valve-per-cylinder datto head has much less breathing ability than the modern 4-valve heads and also the geometery of the A15 head is not as good.

Mazda have a lot of pistons in the 78 to 80mm range. If you want to use cast pistons then the ACL catalogue can be downloaded from their website. Check out the B6, E3, E5 and UC, just off the top of my head. You will need to increase the small end of yoru rods from 19mm to 20mm, ask your local performance shop. You will need to know what compression you want, and before that you will need to know your cam specs. Then you will need to work out what valve resesses you need in the top of your pistons to ensure adequate clearance. I use 0.060" of vertical clearance and 0.040" of circumferential clearance.

I've also heard of galant pistons with 19mm pin, but can't remember wether that was an A14 or A15.

Ernie is selling 80mm forgies - check out the classifieds.

"how long is a piece of string??"

I agree with Dodgeman...you're wasting your time trying to stroke up an A15 in the <1600cc class. Besides, if you want a reliable A15 race motor on a budget then you can't afford to replace the crank with a custom steel unit, and you can't afford to reduce the bigend journal anymore than absolutely necessary. That is a weak point in the crank. I can show you photos of cracked journals if you need proof.

you can take the headwork "all the way" and end up with a slow engine if you don't match all your components together.

So what RPM is it?? 8000, 9000, 10000 ??? I would suggest you will struggle to keep an 8000 rpm engine reliable under race conditions unless you have a big budget and/or heaps of experience. The odd excersion to 7500/8000 rpm in a road car is different to holding it flat for minutes at a time. Chris Peto "the boss" has been racing his 1200 for..um...about 15 years or so??!? Dodgeman or Aiden might correct me here. he revs his to what sounds like 8000ish but also has created a lovely collection of boat anchors over the years - and that's when you know what you're doing. We limit ours to 7000rpm and have shelves of broken bits.

There's heaps of piston options. Thats why I asked you those questions before.

You asked for a guidline - as a starting point, why don't you consider the Wade 54/86 cam with twin 40's and a nice match-port manifold and extractors plus free flowing exhaust. The 1200GX head is a great performer especially if the ports are cleaned up (not increased). But you can port a standard oval port head to the same dimensions and use cut down L16 valves if you don't have a GX head. Double valve springs are a must to avoid piston to valve contact that will destroy your engine in a blink. Get a new set. I don't use roller rockers but Yella Terra sets are available from Repco. Others on this site have experience with them - try a search.

PM sent

that would be a 2-door sedan, not a coupe.

Yeah, right cable. The 1000 4-speed has a different clutch throw-out mechanism to all other a-series and uses a shorter clutch cable. I'm assuming you purchased the T-50 from Sidedraught...is that correct? If so, you should be right. Otherwise if its a strandard T-50 straight from a celica or T18 then you'll need to combine datsun and toyota parts to convert it to cable operation. Thats easier than converting to hydraulic. I find cable much smoother and maintenance friendly anyway.

That is good information and well explained Dodgeman. But what about the park brake cable ??

As the title suggests, I'm looking for the best value brand, type and place to buy some race seats for my 1000 coupe. I'd consider decent used seat(s) if I come across any, but I haven't yet. What's out there ???