Daniel has answered all questions beautifully,although keeping a15's together is not really hard going on personel experiance.The car recently sold was always red lined at 8300 with an odd flurt to 8600 and it never went off.However new big end bolts where part of every rebuild along with oil and filter every outing

thanks for all this guys, ive also been in consultation with my boss, Adam cope from ACM, he does drag racing motors and bits and pieces here and there so he is going to help me build it, along with some of his contacts.
the basic idea for the recipe are:
flattops, (mazda or acl), no idea of the rods to be used basically the size needed to achieve this, no idea of the cam size (got to check with adams cam man), no idea of the valve size, double valve springs, roller rockers, no idea on the headwork, including shaving or chamber parts, (check with the head guy adam uses in oberon), and fuel injection with a wolf 3d ecu. thats what i have so far.
the reason for stating the 88.5mm stroke is that i was reading throught the wiki and saw that "1608cc is commonly got with the combination of a 79mm bore and an 88.5mm stroke."
i even sat down with my calculator for a while (after asking the q') and worked out that that would give me a capacity of 1735cc, ????? so sorry bout that guys.
i understand that the world of engine building is that you have to make your own mark in the sand, so thanks again for the help.
my current A15 is built to run at 8000rpm. aparently it has the mazda flattop pistons, no idea of the bore size, no idea of the headwork or valve size, but the cam in it wont go at anything under 3000-3500 then pulls to around 5000 then pulls harder all the way to 8000
so two things have been settled for good, 79mm bore, and its pointless offset grinding the crank for the class of racing im going to be in
thanks again guys, muchly appreciated

Thats consultation Kurt!!! Confrontation with him and he'll flatten you....

Dropped in to see you in the new workplace yesterday but was strartled by the hot Torana, AC Cobra and the nice XY ute out the front. Sounds like the A15 is going to get a workout, maybe you could just rebuild me an A12 for practice!

all better now, lol

yeah its a whole lot of fun working woth adam, constant dyno tunes, anything from 10 to 40 grand engine builds for his drag cars an bits and pieces.
the boys were saying something about you popping in, but they couldnt describe you well enough for me to decide definatly that it was you, but i did guess it was you!
the torry is getting a bad assed turbo 202 conversion, nice looking body but not straight and has rust under the paint, the cobra had a brake problem, all gone now, and the xy is going back to orange to its owner to finish off the interior.

just for the record guys, we are talking around 10 grand just for the engine, the car is already setup to take the strain so that is one problem down.

i almost forgot, does anybody have any air flow test diagrams fo the A15 head?

cheers kurt

Most successfull race engines aren't just 'built' but developed, sometimes over several years before power, reliability, handling & driver skill all come together. [I'm still waiting LOL]

Most racers start out with what they can afford & make improvements as money or necessity [from blow ups] allow or dictate.
Even 'the Boss' is still thinking of ways to squeeze a little more grunt & a few more revs out of the willing A15.

from what ive heard dodgeman, it isnt an A15 anymore, but a CA16, or has that gone by the way side.
i think one of the best things for me to do is to strip down my current engine and measure everything up, as a base guide.
the one and real only down side to that is that i wont be doing any racing in it for the whole year. , its just what would happen if i was to do this.
that is why i am trying to do some homework

It sure is still an A15. the CA 16 is still in the build process in a different car.

I dont see how stroking to 85 plus or minus 0.5mm is a waste of time compared to 79mm bores.

You have to sometimes go through quite a few blocks to make sure you can. You have to x ray them and make sure there is enough cast iron in the right places and then you wont be able to bore them out later meaning new block if something little happens and many more issues like cracking between the bores.

If you stick with 77mm many pistons choices are available and also sleeving options.
Also the torque curves are going to be better with the mid 80s stroke.
The most successful 2ltr engines of all time ef, fiat twin cam, sr20de, renault mi16, Honda h22/d16/b18, toyota 3sg and others run 86-90mm strokes.
Some of these engines have awful RS ratios yet are monsters.

Quote:
From time to time I make reference to 'The Boss' & the 'Secret Weapon' This is the second 1200 coupe that is progressing at a snails pace.
I guess there isn't much motivation when the old car is still so competitive.

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.