Can displacement be replaced?

Discussion in '2000 Honda S2000' started by turbo power, Nov 29, 2002.

  1. NOTE-Please when reading this try to keep an open mind, and try to keep from just posting "you idiot" or things like that with no reasons to back it up because that gets us no where. Also I hope I didnt make this too confusing due to bad wording becuase i really want people to read all of this.

    Many people say that there is no replacement for displacement, meaning that you start with two generic 3 liter v-6 blocks and bore and stroke one out to 3.5 liters it will be more powerful and therefore faster making size the only way to build a fast car.

    However, did anyone ever stop to think that if through lighter internals and better cams that you could take those same two 3 liter engines and say have one take its horsepower reading at 6 thousand rpm vs 5 thousand making the first engine more powerful Wouldnt that then mean that there was no replacement for revs?

    What if the two motors were idnentical except for one part, one of the engines was a dohc with vvt and the other was a ohv. The dohc with vvt would make more power so wouldnt that mean that there was no replacement for dohc and vvt?

    What if one engine is naturally aspirated and the other has forced induction? The engine with forced induction would make more power so is there now no replacement for forced induction? Now lets say that we are back to two na engines except one has the tvr speed 12 compression ratio of 13.0:1 while the other has a much more normal 9.0:1 would that then mean there was no replacement for a high compression ratio? The same goes for the forced induction side of it. If there is a turbo stuffing 14 lbs of boost (sorry everone im american and dont understand bars of pressure) in an engine and the other with 9 lbs of boost. Is there now no replacement for a high boost pressure?

    What if the engines are the same but one engine has a four speed automatic behind it while the other engine has a 6 speed manual. More than likely the 6 speed will produce the better numbers in nearly every catergory so is there now no replacement for more gears and a manual transmission?

    What if the engines and transmissions are the same but one goes into a car that is 500lbs lighter than the other one. A light weight car will be able to better a heavier one in every performance stat so is there now no replacement for lightweight?

    What if the engines and transmissions are the same and so is weight but one car is 3x as stiff as the other. When these cars are raced on a track the stiffer chasis will have the advantage over the other car in the turns due to its abitlity to handle. So is there now no replacement for the stiffness of a car?

    What if everything on the car was the same except for the rubber on the road? One car has a set of high performance pirelli p-zeroes while the other has a set of low resistance tires that have just come from the honda insight with little traction compared to the pirellis? The car with pirellis would be faster due to loads more grip than the car with the low resistance tires. Pirelli says "power is nothing without control" and it is obviously the truth here so is there now no replacement for traction.

    I could go on like this forever but I think if you are going to get my point you would have gotten it by now. Cars a complex machines and should not be reduced simply to the size of their engines.
  2. Re:

    very well said!
  3. Re: Can displacement be replaced?

    turbo power, all good

    displacement, scientifically, is one of three equally important factors in engine performance. The others being boost pressure and compression ratio. Finally power is calculated using rpm.

    a 2000cc engine with an 9:1 compression ratio with 1.0bar (thats 14.5psi) of boost will have the same torque as a 3000cc engine with a 12:1 compression ratio with no boost.

    litres x compression x absolute pressure = constant

    2*9*(1+1) = 36
    3*12*(1+0) = 36

    so theyre the same

    a naturally aspirated car runs at 1.0bar (14.5psi) of absolute pressure or 0.0bar (0psi) of gauge pressure.
    a Mustang Cobra runs at 1.55bar (22.5psi) of absolute pressure or 0.55bar (8psi) of gauge pressure.

    Gauge pressures are always quoted for cars but absolute pressures must be used in calculations (simply, they are 1.0bar (14.5psi) more than quoted gauge pressures)

    this only works for engines of similar design - same inlet/exhaust, same level of tuning etc but is a good estimation for road car engines
  4. Re: Can displacement be replaced?

    When people say there's no replacement for displacement, they are generally speaking about the engine only, and trying not to introduce too many variables such as vehicle weight, transmissions, final drives, etc.

    Take a look at the graph below. It's a composite of two dyno charts of two different vehicles that basically put out the same hp Around 640-650 RWHP). Even though the peak hp numbers are very similar, the overall driving experience in each of these vehicles is vastly different.

    Displacement by itself will not gain you much, particularly if your engineering mandate consists of nothing more than providing for an engine that will reliably haul fruit. Dodge Ram V10 vs even a normally aspirated Mini One, no contest. But suppose you apply those very same engineering expertises that you've cited for the smaller engine, and transfer it over to the larger engine?
    We've already established here that smaller, higher-revving engines with lightweight reciprocating parts are what's desired in building high hp/l engines. Yet when you look at the rules for Formula One, and you notice that just about ALL of the teams take advantage of the displacement allowances to the full, you see that displacement has its value. Which might be why Honda went with a 2.0-liter instead of merely relying on the already known 1.6 and 1.8 liter engines in its lineup.
  5. Re: Can displacement be replaced?

    Ok first read my sig

    The concept of "There is no replacement for displacement" is NOT that displacement is the only way to get Horsepower, torque, or any other measure of performance out of a car.

    For example take a 2.0L inline 4 and modify it with everything imaginable. It is not unreasonable to expect hp figures of 1,000+, all from a relativly small engine. However the maximum amount of hp that is posible to obtain from this engine will be determined by its size. Reguardless of what modifications are made it can only breathe 2 liters of air per cycle (or anything else you may fuel it with, nitrous ect.)

    Able to breathe more air, a 2.5L inline 4 would ultimately make more power than the 2.0

    And that is why there is no replacement for Displacement.
  6. Re:

    Sometimes, people should note that pure power isn't only only factor to driving fun.
  7. Re: Re:

    I just explained the meaning of the statement I wasnt promoting raw power as the only means of having a "fun" car.

    I wish you would make your posts more relevant and better thought out.
  8. Re: Re:

    No no, my comment wasn't for u, it's for everyone. If I wanna argue or reply to ur post, I would have quoted, just like this one.
  9. Re: Re:

    Its Still irrelevant, "no replacement for displacement" has nothing to do with driving fun. Its more of a pysical property not an opinion.
  10. Re: Can displacement be replaced?

    Everything you said about that 2 liter is answered in my orginal post. It has a larger size and given that all other factors remain unchanged it will produce more power, pretty much common sense. But other factors such as revs and weight could change it so that the 2 liter is faster than the 2.5 liter.
  11. Re: Can displacement be replaced?

    Your missing my point. Displacement shows its value by making the most of tuning.

    Here's an example:

    *The subaru WRX (US version) has a 2.0 liter Flat 4 fed 14psi of boost via a turbocharger this all equals = 227hp and 217lb/ft of torque.

    *I have a 1993 GMC Typhoon, It has a 4.3 liter V6 and is also fed 14psi of turbo boost. This produces = 280hp and 360lb/ft of torque.

    Despite being the tunned with the same amount to boost the Typhoon puts out higher figures simply by virtue of displacement. Nothing else can give this effect.

    *NOTE* For those of you that may not know a Typhoon has not other major engine mods other than turbocharging and beefed up internals to handle the turbo.
  12. Re:

    Realistically, it comes down to the fact that yes, it's true, there is no replacement for displacement. Now depending on the weight of the vehicle in question, a smaller engine that can rev up faster may be more desirable, however, in terms of engine dynamics it comes down to this:

    By increasing the size of the bore and stroke, you increase the compression ratio by a means less stressful to the components inside the engine.

    Since engine displacement = Bore x Bore x Stroke x 0.7854 x # of cylinders

    AND compressions ratio = 1 + (0.7854 x Pie x Bore x Bore x Stroke / 3.902439 Cubic Inches (Approx. chamber volume) + 0.4895356 Cubic Inches (Approx. head gasket thickness) + 0.047713 Cubic Inches (Piston/Deck height) + Any Piston/Dome relief volume + 1, then devieded by 8.1015199,

    It's complicated, but still easy to see that the two are directly related. Anytime you can increase compression ratio, you increase engine performance, and that's good, period; when you can increase compression without increases stress on the engine parts, that's better.

    Forced induction is, in essence, increasing engine displacement by another means. Engine compression ratios must be lower, but only because you are introducing compressed air into the engine block. A 3.0 liter flat-6 Porsche engine with a 1400-cc 6-guage roots-style blower is, in essence, a 4.4-liter engine, since 1400cc's of air are compressed before being introduced into the engine block. The only difference, in this case, is that the 3.0-liters of total displacement in the engine block itself is all that can be evacuated with two turns of the crank shaft, causing to rev higher to produce the same amount of horsepower an actual, naturally aspirated 4.4 liter engine with a high compression ratio would have to.

    So, in the end, displacement is better when you are talking about making more horsepower with less stress on the engine block itself. Although, being a motorcycle owner, I know how fun it is to rap up a 4-cylinder to 10,000 rpms, for horsepower and decreased engine wear, there is no replacement for displacement.
  13. Re: Can displacement be replaced?

    oh dear, imperial formulas are a mess!

    good ol' metric leads to displacement of 1/4Pi x bore x bore x stroke x # cyl

    compression ratio = volume at BDC over volume at TDC

    a small turbocharged engine will have exactly the same characteristics as a large atmospheric engine - if its a modern anti-lag Porsche motor like the GT2/Cayenne
  14. Re:

    ...which is exactly my point, Chicane: turbocharging essentially does increase engine displacement, since it acts as a preliminary compression chamber for the condensed air before it introduced into the cylinder block.

    Therefore, as long as you can keep pressure high at low RPM's, a smaller, forced induction will, as you stated, perform similarly, if not even MORE efficiently (but with higher output), than a larger displacement motor. Hence, there is STILL no replacement for displacement.

  15. Re: Can displacement be replaced?


    the point of an engine is to efficiently burn as much fuel as possible, this amount of fuel requires a certain volume of air, this volume is the displacement, more power needs more fuel needs more air needs more DISPLACEMENT. Its not an americanism at all

    what IS an americanism is having large individual cylinders, 0.7 and 0.8-litres EACH is common (even 0.9 & 1.0 sometimes), whereas in europe and japan we tend to keep it down to a sensible 0.5-litres and just have more of them.
  16. Re:

    Touche. Hey, at least we got the point right, huh? (Ha, Japan sucks... J/K).
  17. Re: Can displacement be replaced?

    of course, hell i wouldnt care if a Viper was coal-powered, just as long as it gets 500hp. I can think of 3 very good reason why japan sucks, 3 numbers...2, 8 & 0. 280hp does not a supercar make, get rid of it and lets have some sensibly powered performance cars please Japan. Im not the only 1 who would pay good money for a quad-rotor RX8 am i?
  18. Re:

    Amen!! And I thought I was alone in the world.
  19. Re: Can displacement be replaced?

    Well you can rest easy, as those numbers have gone away. Nissan's already reworking the GTR, scheduled to be shown in '04 relased in 05 w/ a TT V6 plant, electrically assisted turbines, and meeting Euro4 emissions regs....
    The engine is to designed around 400hp and 480NM, and a new form of Attessa AWD using inputs from slip and power output.
    The body and chassis is based on the Z, weighing around 3000lbs. Suspension produced in conjunction with Lotus.
    Target price 60k USD. Nissan/Renault specifically stated they were going to outdo the Viper for a lower price. Interesting.....
  20. Re:

    400 horsepower, $60,000 TT car?? 405 horsepower, $50,000 N/A car?? $65,000, over 500 horsepower, N/A car?? Not very interesting, if you ask me.

    Electric-assisted turbines. That's starting to sound more like Turbo-assisted Supercharging. Interesting concept, though.
  21. Re: Can displacement be replaced?

    thats all well and good but 9 years ago Toyota had a 330hp (US) Supra, what do they have now?...a 190hp FF Celica. The NSX has 10hp more than it did a decade ago, its a fabulous car but it could be so much more. The new 350Z has less power and torque than the decade-old 300ZX, the Mitsubishi GTO hasnt been replaced, Skylines have been pretty much stagnant since the introduction of the R33, Mazda have taken a step backwards with an NA rotary and got rid of the triple-rotor Cosmo.

    I LOVE japanese performance cars but its so disappointing that all the good ones are 5 or more years old. I want a V8 RWD Toyota, a 450hp Skyline, a V10 NSX, a quad-rotor RX8 etc etc. Evos and WRXs are world leaders, why not other categories?
  22. Re: Can displacement be replaced?

    turbo-assisted supercharging? used by Lancia in 1985 to great effect.

    i wonder where the electricity is gonna come from to spin the turbocharger, not the alternator i hope

    whats wrong with Porsche and Audi's anti-lag system?
  23. Re:

    I was just thinking the same thing!! (about robbing power from the alternator - something's got to turn that, and then you might as well be turning the damn turbocharger itself - vualla!! Supercharger).

    Explain what their anti-lag system is, and I'll tell you what's wrong with it.
  24. Re: Can displacement be replaced?

    I haven't seen the blueprints on their electrical assist so I couldn't possibly tell you how it works. I would gaurantee they have someone a bit smarter than you who developed it. I seem to recall a number of people saying Static Excitation was impossible before it was developed. Who ever thought we would be using soundwaves to act as a compressor in place of refrigerant in an A/C plant?....etc, etc

    By the way, there IS a 450HP Skyline, and it had a purchase cost (brand new) of 42,000 USD (depending on the year). GTR N1...which also came in Vspec and Vspec II variants. It also weighed a bit less (3280 lbs). It had a number of item deletes, but (like the ACR) you could add them in (for a price of course).
  25. Re: Can displacement be replaced?

    No idea how anti-lag works on road cars. On WRC cars unburnt fuel is ignited on its way out of the chamber, keeping the turbo spinning and causing the exhaust pipe to crackle and pop (so i heard)

    R32, once upon a time cold fusion was thought impossible, guess what?...its still impossible

    I thought N1s were racecars, and no way do i believe u that 450hp worth of Nismos finest could be bought for $42k

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