question on displacement and other things
 

thank you in advance,

TRUE or FALSE.
2.2, 2.3 or even a 2.5 liter evo enging block will produce and handle same x amount of power.

If false, please if anybody has time, explain to me the world of displacement AS FAR AS EVO'S ARE CONCERNED. (note the caps. i know that the bigger the displacement the more power you will produce. True for the domestic cars such as camaro's and stang's.) But as far as evos goes. I notice on this forum that ppl are building 9 sec cars with a 2.2 jun kit and 2.3 ams kit. I dont see any 2.4 or 2.5+ if possible.

Reason for this is because my car is completly stock and im thinking of building my 4g63 motor first. Forged piston, longer stroker, cams/gears, port polish, bore up ( what displacement would be best ). and all the goods stuff i may have missed.

From there i will see what turbo kit i should slap on.
I really dont know why i came up with this, i just find it in my little brain that it makes more sense building the motor first before adding crazy mods to the car that may not be able to handle all at once.

Before you answer any of this. Tell me first whether this is such a good idea. Is it also beneficial or may cause more harm than good. I dont know but an answer to this will make me shut the fawk up.

A long stoke engine isn't able rev as high safely as a short stroke engine.... but the long stroke engine will have better low RPM power, and will be able to spool up a large turbo earlier in the RPM range than a short stroke engine.

For a full on RACE engine you are probably better off with stock displacement, for high power street use a stoker is a blast.

Keith

There's an old rule of thumb, that, all other things being equal, peak torque is governed by displacement, peak power by bore, for just the reason above.

Dave

so what are you saying???? having high rpm range is really not necessary as long as both displacement and bore are equally worked on??

You'd make teh Most WHP on a 2.0 cuz you can rev the highest

I believe ams or rnr sells fully built 2.4l blocks and the 2.3l stroker kit. I am doing a 4g64 long block swap and with it fully built Mynes Performance is assuring me that an 8k rev limit won't be a problem, thus best of both worlds. I have also been told that I can expect about 50whp and 100wtq just by going to the 2.4l with out any of the supporting mods. I think that you definately have the right ide building the block first, then you will see much bigger gains from future mods like cams, head work, gt40r turbo etc. The Mynes shop evo has the 2.4l and was achieving full boost at 2,200 rpm with the stock turbo so that is another big advantage over the 2.0l.

:lol: :lol:

guess I'll swap my motor for a 20,000 rpm chainsaw engine

:lol: :lol: :lol:

More power is made on the 2.0, keep laughing, it's a fact :) Why? Tiny stroke, big boost. Look at a Supra motor, almost the same dimensions cept for 2 extra pistons, makes big power, but your know what makes even MORE power? Yep the Skyline motor, which happens to be smaller.


You stoke and Evo motor, you limit it's top end, so you limit it's MAX whp as well, you INCRERASE low end torque for sure, but if you wanted all out WHP, a 2.0 would do it.

:lol:

Rpm limit is a function of the square of the bore and stroke. It's about piston speed. A squared 2.4 will make more hp than the same square on a 2.0; basic physics. {pcfreak}

Bore doesn't affect the rev limit, at least not to the same degree as stroke. A larger bore may mean a larger, heavier piston with more friction at the rings, but it's the peak piston speed that usually sets the limit (OK, assuming you have a valve train that can handle it).

Sure, a square 2.4 will make more power than a square 2.0 because the displacement is 70% greater. But if you start with the square 2.0, stroke it, and have to drop the redline you might not get any more peak power. You'll have more torque throughout the range but you may have to go to higher gearing to make up for the rpm loss and that'll lose some of the torque advantage at the drive wheels.

Dave

I would seriously consider a 4g64 block with 86.5mm bore and 106mm custom stroker crank if you plan on running a monster sized turbo... full 2.5 liter displacement :D

Keith

Rod to stroke ratio also comes into play. Might be a good idea to get a deck plate put ontop of the block to run longer rods?

what i'm shooting for is a motor capable of 400- 500whp w/out any problems in the long run. The stronger the parts in the motor the better it will perform right??
I just dont like the idea of squeezing the most power out of a stock motor, i get the shivers when i think about it. I want my motor to be able to back it up. Also I plan to purchase 2 turbos. One is a monster size turbo when i feel like dragging and the 2nd one is a decent size turbo thats powerful enough (like a gt3071r for example) for track days. I should also be able to swap these anytime i wish to do so..hehe.

im not really a big fan of dragging an evo. i think its cruel that ppl do that to their evo..heheh j/k.

Im more of a circuit type of guy you know. Anyway any ideas or info is greatly appreciated.

I thought we were talking about the 4G63 Block? That’s what I was talking about, not you’re made up square 2.4 blocks.

Simple Physics?

2 MAJOR things dictate engine power.

1. HEAD Design, you head, how efficient it is, how much air it can flow.
2. Your Aspiration, turbo, Nitrous, and so on.

The rest is secondary. AS of right now, if you want to make the MOST whp with a 4g63, stick with a 2.0. AS long as the motor is STONG enough, you can always add more boost, make more power. Displacement adds more torque, easier low end power, not necessarily more WHP. Look at the old 5.0 mustangs. Made a lil over 200 HP and had no top-end, why? Cuz the head sucked. Another 10 liters would have done nothing.

The comparisons between the Supra and Skyline engines are invalid. Displacement is NOT a determinant of maximum power potential. Valve area is the overwhelmingly largest determinant of power potential. Valve area is tied closely to bore area.

Given a limited octane rating, and a limited boost pressure, the engine with the largest valve area will make the most power - condition being that the valvetrain and the shortblock can take the revs. Rev limits are about component acceleration, loads, and the using up of a finite life cycle. As RPM rises, not only do accelerations and loads increase to start fatiguing the components, but the cycles occur at a much quicker rate, reducing mean time before failure. Piston speeds are not a problem, but they DO roughly reflect component acclerations and loads, so they are taken as a quick and rough method of assessing how stressed an engine is. Many engines from high tune daily driver engines to 24 hour endurance, to current F1 engine, all range in the 23-26m/s mean piston speed window. Component accelerations of an F1 engine are over twice that of the rest though it correspondingly runs about half the stroke. This simply is because it revs over twice as high and the inertial loads rise as a square of increase in engine speed.

All displacement allows you to do is to do away with the need to rev to make the same level of power. Lower rev, lower accelerations, lower loads, longer life. If longevity is not a concern go 2.0 and rev it sky high and then use the high spcific output figure to brag to your friends. If you want to make reliable power at a lower engine speed, stroke it.

2.0 vs 2.4 stroker, same turbo, same boost levels, same valve area, the 2.4 will make slightly more power because it is making the most efficient use of the air it inducts. At a lower RPM, there is much less friction. This is similar to air restrictor racing (both venturi and sharp edge orifice) where despite the absolutely limited air mass induction, teams always aim to stuff the largest engine they can below the restrictor and turn LESS RPM. Specific output figures are unimpressive, but as long as output/mass figure increases, it is a plus.

Power for power, rod ratio wear and power effects are extremely small compared to the effects of reduced engine speed (from bumping stroke). Anything 1.5 and above, I would run.