I did a search and struck out. For an A14/15 what is the maximum bore. I will be hunting an A15 crank for the A14 soooo I wanted to see how far out can I safely and easily bore the engine? Looking for off the shelf pistons. As long as I have to get pistons I might as well see if I can get more displacement right???

Thanks for the help.

Tom

Mine is currently at 77mm up from the original 76
I plan to go out to 78mm at Xmas when we do the next build and get some more compression
You can go to 79 and even 80 but you'd need to get the block Xrayed to make sure this is the case on your particular block
Just incase there is some core shift and the walls are abit thin in spots.

Ive been researching extensively on improving the capacity of the a15.
I found that datoman 1000 is right to be safe and stay with 77mm for good sense.
I also found another way to go the way that "engine masters" are going for their 850hp 8litre v8 competitions. They are going small bore and long stroke to get the highest and best torque throughout the rev range for the last 3 or so years instead of square bore and oversquare bore engines.
Having said this if you are going to be serious in capacity increases over 1600cc a 90mm e16 stroker crank machined to fit the a15 will be the way with 20mm longer rods (149mm z22 or 152.5 mazda rods).
To achieve this a spacer place (like Jun and MUgen have for the SR20) will have to be made to accomodate the longer rods to help the rod ratio and sleeving the whole assembly with 79mm offset bores or 80mm if possible with a step on the base of the block. A Feral or Jts oval port head will finish the job off and also a Proinjection liguid vapour injection LPG system for economy.
1765cc with 79mm sleeve bores or 1810mm with 80mm offset sleeve bores. With billet sleeves you could also turbo the lot.Youll also need some high quality longer head bolts to torque it all down and the rest of things like SS or copper head gasket, arp rod bolts eg.

There was a thread that I was following somewhere that a guy used Subaru Justy pistons in an A14 or A15. They were the right bore, (meaning the largest bore that the block could take) the pin height was off a bit but when the inverse dome (dish) was machined off it made the pin height about right and the pistons were inexpensive. I will try to look that up and post a link.

I was considering using these pistons in an A12A until I decided to just go with the SR20 in my car. (My car will ultimately end up with an SR16VE just fitting it up with a 20 for now.)

Arghhh! There's no substitute for capacity! Thats true - but they're some pretty wild mods you mentioned. I've been there myself plenty times!!

We've had great success with 78mm. I would feel confident with a 79mm block IF it was ultrasoniced by a good machine shop and bored accordingly, and it has minimal corrosion. It doesn't make that much of a difference anyway. Overall power is limited by how much the head ports and valves will allow.

Thats why an A15 bored to 1600cc will never be capable of producing the same power and torque curves as an L16 is capable of. Bigger bore of L16 means bigger valves.

Manufacturers tend to use the long-stroke, small bore arrangement because it provides a greater thermal efficiency due to less exposed surface area for a given capacity. This helps with emissions. This is particularly true for motors made to a budget...ie when the engineers don't want to refine the motor too much or use expensive sensors and computer technology etc.

If you want a spacer block, I can CAD one up for you and have it machined here at work. Yuo should then bolt it too the block and bore the pair of them together!

someone had mentioned E15et pistons for a larger than average A15. what's the story with that?

it's not LPG for economy, it's the ease of boost and the significant power boost at 12:1 compressions.

the good for the environment and lower cost thing is a diversion ;)

I'm pretty sure the E15ET pistons are still the standard 76mm bore common to A14's and A15's. I think the turbo motor had a special piston jsut to lower the compression. Unless you are turboing your motor, why would you use it??

i was just thinking about this today. what do you rekon (becuase im not to smart to figure out the cc by mm) the biggest cc you could bore out the a15 to?? Not trying to hijac thred just trying to add to it

daniel, exactly right about the ports!!!
The A18 would have to be boosted just like the poor flow of the naps Z18 engine. The pollution head design of the naps engine did well with boost for George Fury.
Id love to get a spacer plate made up if I was still going A series. But I recently bought over ebay a 12v engine from the UK that will hopefully solve all my capacity and fitment issues. The engine is all alloy pressure die cast block and head with different sized inlet valves. Inlets are 36.3mm one, the other 30.3mm with one 40.5mm exhaust. The valve angles of this engine are the magical 16 or 18 degrees. although a 2.2 litre engine 90mm bores instead of 88 can give me 2.3 litres. The best thing is that this engine with a renault fuego compact waterpump makes it 1 cm longer than an a15 and the low height design head makes it 5cm taller. It can drop almost cm lower on the datsun 1000 crossmember by using a dry sump setup. Ill post up some pics of the same engine with the earlier taller 8v head to show everyone why I chose this engine to be perfect. At 4Okg lighter than an sand cast alloy sr20de both fully dressed it was made for the b10. The block is 231mm tall which is 4cm taller than an L20b but the head is so short and the length is so much shorter than an L series that it freaks me out how much better wet sleeve blocks are when they are pressure die cast.
For a nice article on engine masters...enjoy the read...
http://popularhotrodding.com/tech/0603phr_emc/index.html

Also daniel, the deck will have to be stepped and sealed to make sure its on well and no water squirts out.
Cmon daniel the kb10 will love you forever!!!
kb10 + t50 + H190 and A18 with a to4z with 12 psi..... you know you want one