i have a A14 bottom end, A12GX head, twin 40mm dellorto's and extractors. how do i get atleast 140hp out of it? im thinking of 11:1 compression(using different pistons and shaved head), big cam and what else? do theese GX heads need to be ported and flowed? i was told to only make 1 of the valves bigger as the othe valve was big enough? do A15 cranks fit in A14's the A14 i got is out of a sunny wagon.

140hp is 100hp per litre.

i would use the A14 head as it has bigger ports, but the A12GX head also has some nice bits about it too - like higher CR.

i would use injection to make it reliable in the upper RPM, you'll need to lighten the whole rotating assembly (like knife edging the crank and light flywheel), use quality HE pistons, bigger wrist pins, a n-n-nasty cam, double valve springs etc etc.

you may even want to invest in roller rockers, but they're pretty expensive.

or, for the same outlay you could have a near stock engine and a small turbo hanging off the side and close on 180 - 200hp with injection and intercooling.

hey mate, dont have to do too much, im getting 90hp at the back wheels out of a pretty stock a15, running single throttle body injection, what you got will do pretty good the way it is. Research a cam, for this is where most of it is at!!!

it is just like any other motor if u want max power its no different u need heaps of air and fuel and strong parts if u want it to last. it sounds like ur not on a MAX POWER budget by the parts ur talking about. id say sell the carbs sell the extractors and go injected turbo, probly sounds funny considering my turbo setup has twin 45's but injection would be much easier. and yes the a15 crank will go in the a14 crankcase i have the same setup.

i dont think u guys understand. i have twin 40mm sidedrafts, A14, A12GX head and extractors. i will not be going fuel injected or turbo and i cant use an A15, im only allowed an A14 N/A. i have a datsun 1000 ute and getting really more than 140hp is a waste as im not allowed to tub it. i just need info on whats the best to spend my money on. ill maybe only spend about $2k more

With 2K to spend and the fact that you already have those parts I would suggest a cam, some headwork and a compression increase, re-graphed distributor, a well matched exhaust and some time on a dyno to get the whole shooting match tuned to perfection. Is there any way to can increase your budget as getting 100hp/litre reliably will probably cost you more than $2000 IMHO? Little things like electronic ignition and a beefier clutch will make the car alot nicer for example.

Regards Matty

My A14 makes 140hp & its not EFI or turbo. I have twin 40mm webers, good extractors the head flowes 141hp. All your power gain is in the head big valves extencive amounts of porting good spark (series 2 bluebird dizzy from feral) I dont run roller rockers & have not had a problem.you dont need to go to big with the cam mine about 74deg. Lightend & doweled flywheel with arp bolts. Full balance & blueprint will make it rliable. Mine makes power to 7500rpm. I ran it at philip island last sunday & ran a 2.11 second laps holding out to 8000rpm in third & just over 7000rpm in 4th we worked out later that it was doing about 120mph (200km)
And the motor owes me about 4k & i can do more
And all through a standard 1200 clutch,gearbox & h145 diff
Mark