the a12 would probebly be revyer due to its shorter stroke

if the car goes better why do u need it to rev? if its making better power at less revs, ull be helping the engine last longer, especially in a khanacross car....

Get a big cam and make the bastard stay over 8000 all day..... Sh#t it's only an engine that gets used once a month! Rebuild it every year if you have too.... Khanas are fun and hard on machinery, thats life!

Matt

i agree with a couple of others there that said around the 5500 mark is tops really for your setup

i try to keep mine below that... doesnt always happen... hitiing upto 7000-7500rpm has made the flywheel come loose a couple of times

Well with that in mind then....

What would be the first thing you would do to give it more grunt between 3500-5500 rpm?

Get a lightened and balanced flywheel, that will make the engine rev up quicker, especially when combined with a 'bigger' cam.

A dyno would tell, but lacking that here's my impressions from the A15 I had. A stock A15 revs to 6000 no worries. The limiting factor in "how high" it will rev is the valve springs. All stock A-series engines rev to about this much with the stock valve springs. The GX double valve springs were good for 6600 rpm if I recall correctly.

Maximum power is at about 5000 rpm, the limit here is the stock Hitachi carburetor.

With a weber 32/36 downdraft carb it will make max power is still probably 5000 rpm. The stock camshaft is tuned for about 3-5k rpm. The "how hard" it revs I guess you are talking about acceleration, max torque will be around 3000-5000 rpm. This is where you feel the engine pull.

The max of the airflow through the stock cylinder ports and intake manifold is maybe 5500 rpm for an A14 and a bit less for an A15 (the A15 doesn't need to rev as high to make the same power). You can rev higher, but won't make more power or make the car accelerate faster.

As mentioned, a worked A15 will happily rev to 8,000 rpm and beyond without causing any damage, let alone undue stress:


8,000 rpm A15

I checked the timing on the a15 yeaterday....at idle with vac line off the dissy it has 20 degrees of timing at idle.....spec say 7 degrees......yet with less timing it idles real crap.

Quote:

But what does it do when reving?

If i give it a rev with the vac line off the timing slowly increases as the revs go up which shows the mechanical advance is working.

When I stick the vac line back on it increases much quicker which shows the vac is working also.

The car does not ping at all and it only gets 98 octane fuel.