Hondas NA engines

i agree with speedcore "The only replacement for displacement is revolutions."

I hear alot of ppl saying on these forums that the b16a isnt the torquiest motor around becuase it is of small capacity ie 1.6 litre. thats true but compared to any other 1.6 litre NA car its miles ahead.


pornstar, i also realise that the stroke and the bore size determine the displacement of the engine but you can either have short stroke/large bore engines or long stroke small bore engines. you could have 2 engines that are 1.6 litre but they both have a differnt bore and stroke.

In laymans terms, if u were to have a running race with 2 ppl and one had short legs and the other had long legs and both ppl were of equal fitness and weight, the person with the longer legs ( longer stroke would win ) perhaps this is one for the reasons for honda engine to be of small bore long stroke design.

I guess you could say that the smaller the bore the less piston area there is for the combustion process to do its job but honda fix this by making high compression motors with good intake/head/exhaust flow capabilities (DOHC) plus the addition of VTEC which produces a strong combustion stroke. so, with each combustion stroke there is enough cylinder pressure to push the piston back down fast then expell the burnt gases fast, then suck in the intake mixture fast then compress the mixture fast and so on.

All this combined with the fact that honda engines are built like swiss watches means that they hold together at high revs which ultimatly are needed to make high hp out of small capacity engines.

we all know what vtec stands for and what it does but it is cruicial to the effieciency of the honda DOHC engines ( b16a,b18c,h22a)

every one knows that in lower revs the less agressive cam is being used, this maximises low end power and torque, but above 5 grand if u didnt switch over to the agressive vtec cam the motor would lose breath as it cant get anough air into it and becomes ineffiecient hence why you would lose power, but the motor switches to the agreesive cam and its like the motor has a 2nd wind, there is plenty of air getting in and out of the engine, so the motor can cram more air/fuel mixture into each cylinder while revving off its **** producing big power out of its small capacity engine. Vice versa if u tryed to use a high lift can in low revs, it would not be efficient becuase it would be lumpy.


it all comes down to the efficiency of an engine to how much power it will make per litre. Honda are smart ppl and they know how to build an engine. they want it to rev as they know revs = HP just look at the s2000 engine and try tell me thats its not a work of art.

Honda choose a longer stroke because a larger piston moving up and down on a short stroke is less efficeint than a small piston moving up and down on a long stroke And, the longer the stroke the more power than can be produced ( just like i said before with the 2 runners)

have you also noticed that honda diff ratios are fairly low, this is because if u want a higher ratio, you need more torque, something which small capacity honda engines cant possibly make.

anywho, why are we questioning the design of honda motors? they are the shizznet. lol.


cam.

nice answer h22a :)

The only thing tho is this, in ur 2 runner analogy, u dont take into the effect of the bigger bore compensating the power that the longer stroke does. IE if you were to put this into analogy, the runner with a shorter pair of legs has more leg strength as the runner with the longer legs and therefore every stride that he takes is equal to that of the longer runner. IE the capacity of the engine is the same, therefore as is the same situation as the runners.

You've raised a concern that I've been trying to lead to, that the efficiency of the engine is the reason for having the longer stroke. You said that the big piston on a short stroke is less efficient than a small piston on a long stroke. Could you expand that? This is where Im abit uncertain.

I think you guys are missing the point of my question, my question isnt about waht the longer stroke does for the engine, its about the fact that a shorter stroke engine will rev much easier than a longer stroke, so why did honda make it hard for themselves by using a long stroke?

cheers, this is really informative, and hopefully more people will be able to add to it.

I just assumed as with what was poster before, they made the b16b and decided instead of boring it out they stroked it for more power for the next model up.

-2ds

Quote:

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Originally Posted by pornstar

I think you guys are missing the point of my question, my question isnt about waht the longer stroke does for the engine, its about the fact that a shorter stroke engine will rev much easier than a longer stroke, so why did honda make it hard for themselves by using a long stroke?

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That's exactly what i was wondering too. I mean you look at somethign like the F20C which revs to 9K rpm yet it isn't anywhere as square as the SR20DE (which has a nice square bore/stroke). Maybe someone can enlighten us as to why these high revving Honda motors have such a large stroke compared to its bore size. I mean if we have engines that aren't square / over-square revving to 8K+ reliably, imagine what Honda can do with a nice square design!

Getting back to the topic I think quite a few things contribute to the strenth/reliability of the Honda engines. Most imporatnt I would say are the bearings which are manufactured to the highest quality from the factory, good head design and capable ECUs help create great power and contribute to reliability, not to mention light and strong rods that are suited to high revving applications.

That said I think there is a large emphasis on peak power value and the lack of torque is mainly mainly due to the fact that some of these engines have pretty slow piston speeds. I think the design emphasis has been on high reving, reliable NA engines and Honda have done a great job at it. But why not choose a more equal bore/srroke ratio?

Quote:

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Originally Posted by 2ds

I dispute that. they could just have easily decided to make power by increasing the displacement instead of making the engine rev high.

-2ds

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Why would they do that?
What cars over 3L have succeeded in the Japanese market. Not only do emmisions laws hurt them but the public doesn't want high capacity engines.

All engines are a compromise.

They can get around the fundamental problems (poor rpm's being the most major) associated with long strokes through building their engines well.

What limits an engine to rev? Ring flutter, breathing, friction, thermodynamic inefficiency......catastrophic failure.
Basically if you build them well, build them light, use the right fundamental design (dohc in this case) they shall rev (to an extent).

Long stroke = torque and powerband

Little 1.6L hondas with short strokes would be horrible. Yeah they could rev high, but they wouldn't be any fun unless matched with a good 10speed gearbox. Motorbikes can of course get away with square/oversquare low capacity engines because the're bloody light.

Honda have worked out what there goals are and built engines around those goals.

Quote:

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Originally Posted by h22a accord

Honda choose a longer stroke because a larger piston moving up and down on a short stroke is less efficeint than a small piston moving up and down on a long stroke And, the longer the stroke the more power than can be produced ( just like i said before with the 2 runners)

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Not quite right.

I think your getting confused over what efficeincy is.

The efficeincy of an engine is how well it turns chemical energy into mechanical energy.

If your however your talking about the potential for peak power oversquare engines generally win out: Think about F1 engines, motorbike engines.

Quote:

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Originally Posted by carbine

Why would they do that?
What cars over 3L have succeeded in the Japanese market. Not only do emmisions laws hurt them but the public doesn't want high capacity engines.

All engines are a compromise.

They can get around the fundamental problems (poor rpm's being the most major) associated with long strokes through building their engines well.

What limits an engine to rev? Ring flutter, breathing, friction, thermodynamic inefficiency......catastrophic failure.
Basically if you build them well, build them light, use the right fundamental design (dohc in this case) they shall rev (to an extent).

Long stroke = torque and powerband

Little 1.6L hondas with short strokes would be horrible. Yeah they could rev high, but they wouldn't be any fun unless matched with a good 10speed gearbox. Motorbikes can of course get away with square/oversquare low capacity engines because the're bloody light.

Honda have worked out what there goals are and built engines around those goals.

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over 3l ? who the hell is talking about over 3l, up until recently honda didn't seem to want to release anything over 1.8l in their smaller cars. they could easily have gone to 2 (as they more recently did) and i'm sure the japanese market is full of >1.8l sucess stories (nissan anyone ?)

I drive a little 1.6l honda with a short stroke and it's doesn't need a 10speed gearbox the current 5 speed is fine =p Incase you didn't notice the b16a's are oversquare!

Now back to your original horribly wrong statement which you have tried to obfuscate with this post.

You said "Honda doesn't make engines specifically to rev high. They make highly efficient engines that are built with quality materials and quality machinery to high tolerances, the fact that they rev high is a consequence of this."

This is a total load of crap! You expect anyone to believe that their engines rev high by accident! They specifically decided to use RPM's to achieve power instead of displacement, among other things they never would have developed VTEC the way they did if what you said was true. There is no purpose to multiple cam profiles if you are not specifically building a high revving engine.

-2ds

carbine, your comment "The efficeincy of an engine is how well it turns chemical energy into mechanical energy." makes absolute sense.

Wynode hit it on the nose with saying "Most imporatnt I would say are the bearings which are manufactured to the highest quality from the factory, good head design and capable ECUs help create great power and contribute to reliability, not to mention light and strong rods that are suited to high revving applications."



Sometimes i have trouble explaining what i want to say.

I think of the size of the piston contributes to the weight of the piston and if u have a heavier ( larger ) piston moving up and down , especially at high revs there is alot of strain on the rods and bearings compared to a smaller piston travelling at the same speed. I have heard of holden red motor pistons letting go and going through the bonnet of kingswoods under high revving applications. I Guess i should have replaced the word effiecient with reliablity.


I still think that the long stroke small bore design of these honda engines relates to the over all efficiency of the engine because to make these power outputs from what is essentially a small engine honda have spent millions engineering a motor to do so. Honda's are unique engines, but the power they put out per litre is also unique. I guess they figured they had to go the hard option with the long stroke small bore design.

saying that, stock honda motors are almost unbreakable, how many hondas do you see getting around with high km with an engine still as good as gold.

think about this, a v8 5.7 litre commodore ss motor puts out max power of 250kw.

it might put out big numbers but its not as efficient as a b16a engine which produces 120kw from a 1.6litre 4 cylinder.

Im talking about max power , max torque is a different ball game.

i have in a motor magazine at home somewhere how to measure the effiency of an engine its something along the lines of kilowatts divided by the number of cylinders divided my the revs at max power( not sure if thats the formula but u know what i mean. you end up with a figure which you can compare different engines with, you cant however compare NA engines with turbo/blown engines as it will give a false reading.

i will dig it up and post it here.


good discussion guys, keep it going.

Some good info, but I don't think you can even compare the old generation of big-block pushrod v8s with just 2 valves per cylinder. They're just high capacity engines with little development for reliability and revability. At high RPM the valve train just can't keep up and this is one of its major drawbacks. These engines just don't have the RnD that Honda engines have when it comes to balancing components and using the most appropriate materials. I mean Honda have been using all alloy blocks for over 15 (maybe even 20!) years where as its taken untill much less than that for local manufacturers to start using all alloy blocks.

From the above I think this statement really digs at the heart of this discussion:

Quote:

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Originally Posted by h22a accord

Honda's are unique engines, but the power they put out per litre is also unique.

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So lets keep going with WHY Honda engines are soo unique :)

BTW this thread belongs in Technical :)

leave it wyn, im threatening to beat u up nikka ;) thast if u move this thread :)

excellent discussions, but think of this h22a_accord, if the weight and thus pressure of the pistons mvoement is the coonsideration, why not just use light pistons and then honda wouldnt need to work so hard getting everything else so smooth and blalanced :)

I AM NOT HAVING A GO AT YOU, its jsut that ive wondered the same things, if it could easiky be overcome with some light pistons etc, why not do that?

the other counter arguemnt is that the weight of the pistons actually help in the engine turning over at high rpm where the force of the pistons coming up becomes greater than the combustion force going down.


so it leads, why make it hard on urself?

its got me f**cked why they did it this way lol. I might go do some searching online and find out.