Just curious, is this engine together? - How did it go? - I'm looking @ doing a similar set up.

time for an update.
thanks for all of your help, like paul said just keep probeing peoples information and you will get somewhere.
i now have an a15 bottom end in the "development" stage (thanks steve) so far it is going to be crack tested, and the crank will be shot peened and nitrided, the bore will be a 79mm job producing a 1608cc displacement with the standard rod length, despite a very extensive and usefull argument for both sides of the boring out vs stroking debate. arp rod bolts and mains studs are to be used, but im undecided to go with the standard rods or get some aftermarket ones either made or off the shelf. the bottom end will be turning to around 8000rpm, like my current race engine, (its 6 years old and hasnt had a rebuild and still makes 90rwhp)
daniel i dont know how to do static or dynamic compression tests but im sure if i asked adam he would tell me. do you need to know the bore size and the stroke size. i know when i comp tested it it was 220psi on each cylinder.
and with the mazda pistons do they have cut outs for the valve to piston clearance, because mine are visible through the spark plug hole, there are 2 cutouts (i forget what they are called) one for exhaust and one for inlet meaning that the engine could possibly have a large valve overlap or cam lift
thanks again guys

It looks like its been decided against the big stroking for this A15 anyway, but its still intresting in theory.
I think stroker cranks on street engines, eg holden 308's are unreliable enough, cost $000's and too often go bang. the additional piston speed of adding 5-6mm to stroke would mean a lot of work would need to go into balancing etc to have the same redline achievable, and in a race setting where it needs to be constantly up there even more risky.
I think to do it u would be increasin bottom end to midrange torque by greast gobs but nothing much up top end, and for racing its mostly up there all the time.

May I just point you in a slightly different direction for a sec. The A14 has a closer bore\stroke ratio or whatever you want to call it, it's not over square form standard but it makes for a more revvy engine if you were to oversize the pistons and apply all the non stroking related mods to it.

Now it probably wont push the same amount of air through it as the A15 would but it wouldn't be that far off.

I don't feel that kidney shaped chambers are 'that' limited. And chamber velocity can be gained in other ways

The two prices I got for stroking a crank were exceedling rich. I'd be interested if you know of a cheap, quality shop to go to. There's always different lines of thinking and you present an interesting point of view. I hope you build it and prove it works better!!!

Hey Kurt i'm gonna be doing a similar build on an A15 soon. Have you thought about using a harmonic balancer? I found this article which explains the benefits of using one, and i know Chris has been using one for the last few years and his car has been very reliable, despite the 8,500 redline (or maybe more). In fact I think this will be his third season without touching the engine, save for tweaking and routine maintenance. Anyway just a thought.

I agree with everything you say about big bores but the a15 as you say is limited in its design to flow enough for any bigger bores than 77mm in reality as 1 or 2mm over the 76mm standard bore cures most of the shrouding issues.

Having said that you could then go to 78mm x 85mm stroke and you will get 1625cc . Also you will increase the flow velocity of the limited kidney shaped chamber thanks to the longer stroke, therefore increase midrange somewhat and no need to rev so high. You will benefit more than with a 79mm bore x 82mm stroke in capacity, cooling, bore strength and dollars.

Pt 2. Just as important is the machining. I've had to get conrods closed & honed once, so you could do this, you could get the main bearings closed & honed as well, & new cam bearings need honing too.i once sent a block back to the machinist because the cam was binding, think how much power this would have cost. The aim is to get everything square so there is the minimum drag on the rings & bearings. A friend's test for when he's assembled a motor (flat four VW's) was that they had to turn over by hand. If they didn't, he'd pull it apart to find out why. the short block should turn easily with the pistons in it, but don't get confused by the valve springs. if it wont spin by hand, it aint a spinner. This principal was applied from stock rebuilds to aircraft engines.

Also take your time assembling the engine, if you're going to. It's better to get everything right the first time, than get something wrong & then having to pull it apart & redo it. You may be able to track down a factory engine manual, which has a complete section on assembling the engine, from bare block to putting it in the car. An a12 one can be used for the A15, just substitute the torque settings for the A15, which differ in some areas. Please dont be insulted if you've assembled engines already, & feel you don't need a manual, because as the old saying goes, if all else fails, read the instructions .

So i hope i've been of some help,but dont be afraid to talk to lots of people before making any decisions. Talk to Jeff Taylor, track down some other owners, talk to Andrew Dennis, call
Graham Wilkins here in Sydney at Seven Hills,talk to Chris Petersen when you can corner him, & eventually i sure somebody will pay you the ultimate compliment when they come up to you in the pits & start picking your brains as to just what you've done, because you've inspired them to do it too.

i know the A15 in my sunny sedan is 78.85 mm bore with a stock stroke for 1598 cc's. So you don't need a offset stroke the crank. If you did you'd be in the middle of the 1600-2000 class, & it'd probably be best to start with a 2 litre engine if you wanted to be there.

So my recommendations would be 82 mm stroke, 78.5/79mm bore, get the block bored out by a reputable race engine builder, not an engine reconditioner ( i suffer from a badly balanced engine because i made this mistake). Get the Crank cracktested, & if it passes get it nitrided, because they live longer that way.The first a15 i bought was somebody's old race engine & it was cracked in all the journals.

try & find some guys running speedway with a series engines, & see if they can recommend cam grinds, as they need both torque & horsepower from their engines, & an engine that has power below the line is better than an light switch engine. Use the stock rods but get them shot-peened & beam polished, & use the ARP rod bolts. Get it balanced properly, including the front pulley, get a new oil pump as they're still available, use good quality twin valves springs, you can get l16 valves cut down & new valve sets fitted, but you need lash caps as the valves themselves will wear as the ends aren't hardened any more (personal experience again). Get a good Distributor for it, N12 electronic can be fitted, Somebody has used l series electronic, or an RX7 crank sensor has been fitted by someone if you want to use an ingition computer. DCOE Webers (40 or 45 mm) or Dellorto's, or throttle bodies from various manufacturers can be fitted. If you've already got webers, use them.
Do a light clean up on the head, but don't go to far to start with. I know some engine builders claim bigger is better, but i personally disagree. I've read in 2 books about Coventry Climax race engines about how sometimes their engines came back for a rebuild with less horsepower than when they were sent out, because some teams would port them out, notably Lotus & Stirling Moss.

Put a good set of extractors put on, Liverpool Exhaust here in Sydney have off the shelf, mandrel bent sets for A15's into 1200's, & a 2 inch pipe with a small flow-through muffler & out the side just in front of the rear wheel.

Don't forget fuel supply, get the outlet on the tank enlarged to at least 8 mm, use a good electric fuel pump & change the hard line under
the car to a minimum of 8 mm as well. that way there'll be enough fuel at the top end, which is sometimes a problem.