sav180

what about 11.0.1 piston from je wit the notch for the valves with 264 or 272,do u think you would see a big gain from that???

james_240nismo

OK what about taking the top end off a dohc and swapping it on to a sohc block is this possible? And how much would you benefit from it? i know that there is an extensive parts availability list to a dohc it would be much easier to find parts. as well as the added fact that you have sohc pistons which would be with the dohc, so more power right? ofcourse a ecu from a 92 swap.

jramosthe1st!

iTrader: (1)

hold on there chief it's not that simple. while it can be done the result would be a high compression engine with more work and money drooped into it than it is worth.

BigVinnie

iTrader: (2)

Just swap out the pistons..
Less work

240-kid

I have kind of come to notice that KA's dont gain much from High C/R. Cervasa on 240SXF has the full works and only made 187, another guy on AZ240SX made 160 with a Fully stock rebuilt S14 KA with I/H/E and 89 SOHC Pistons. So I would assume that High C/R makes very little to not much improvement.

sav180

i bet they didint get a tuned ecu.or standalone..your not gonna make much power with jus a damn afc...pdm had a car that was bone stock wit i/h/e and light tuning on a stock ecu n made 187 to the wheels...im starting to see tuning is where its at no matter what kind of parts u throw on you wont see any good results with out good tuning to bring that extra oooomph out

BigVinnie

iTrader: (2)

It's all about squish and quench area's. You also have to consider fuel. Alot of these guys that are doing these builds don't increase there injector size, don't increase fuel pressure, and don't tune properly.
Forums are really a place where people do pre school mechanical building.

sav180

where do 370's maax out at?would the 370 wit fuel pump be the ideal spot for high comp or 400-550 injector be better?

sav180

with 93 oct is our pump gas out here in nj

james_240nismo

well see, if we are talking about n/a motors. a well tuned car is the only way to go. like for example if you put a h.p. cam, light weight crank, forged over sized piston, and higher cc injectors your engine will have high hp, but if you really look at the timing of all those events affected by those parts you put in. if you could see the event timing numbers it would look like a mess, sence these parts are made assuming our parts are the same as their's. ecu tuning is in my opinion required every time i do a major upgrade, i.e. buy a IFMS independent fuel management system that way if your serious about your car, you can tune and tweak your timing and fuel every time you make an upgrade. it seems to me a piston swap would be a huge deal since you would need to pull the engine out to do it, i recently swapped heads dew to a dropped valve, i must say it was a heck of allot easier than i originally thought it would be. although if you haven't realized it yet the 240sx is stock, a performance car you can tell just by looking under the car it looks just like the corvette from 88 but lighter LSD and everything, they are very similar.

BigVinnie

iTrader: (2)

370cc injectors would be fine, since 370cc injectors on a 4 banger engine can produce close to 280WHP. It may not be the most efficient though.
With injectors for natural aspiration you may want finely tuned injectors that tune specifically around your HP goals. Since larger cc injectors come with a larger spray tip it might not be the spray pattern needed, or effectively give the spray needed to mix with the air, that will make your air to fuel atomize effeciently.
When I get to that point of high compression for my engine I will probably be using RC injectors that are customized for 300cc injection. That way I can reach the level of 110WHP efficiently by properly spraying the fuel in to what ever my manifold pressure will be for proper atomization. You want to make the combustion process as efficient as possible and atomizing your air to fuel is probably the most important factor.

james_240nismo

I'm glad someone on here understands fuel atomization. nice I'm glad you addressed that. but my question would be if you had a turbo system would the atomization factor be out the window or does it still apply?

BigVinnie

iTrader: (2)

It works a little different because you are dealing with forced induction. Which in any case manifold pressure is more than what the engine can consume naturally already. The pressure applied within the manifold literally starts to split fuel so that the process of atomization is occurring earlier than it would with natural aspiration.

james_240nismo

but usually you hear that a vacuume causes atomization to occur, sence in normal engine function the fuel & air is drawn in via vacuume caused by the intake down stroke. that is what causes the volocitation to cause atomization in n/a engines ofcourse this raises a question at what point does the + force out preform the vacuume. could just 1 lb be enough to cause better atomization? or does it take 5 or more lb's?

BigVinnie

iTrader: (2)

I have an answer for both of you that people seem to forget, and this diagram will best explain the problem when raising the compression via piston surface.
I just went over this in my local forum so I thought that you would like to see where the power losses are using higher compression pistons on the DE, and how to make up for it.