Hondas NA engines

[pornstar]

Why is it that Hondas engines are talked about much more than other high powered high revving Naturally Aspirated makes?

I was talking to an engineeer about this the other day, and he was shocked to say the least when he found out that the b18c runs an 89mm stroke that can rev to 8,200.

The general Consensus is that Hondas engines are unbelieveably smooth and well balanced. Thats how they are able to rev so high with such a long stroke. We got talking some more and got into some theories why Honda traditionally use small bore and long stroke engines when they are required to rev high, which can be done much easier with a short stroke crank.

Anyone wanna offer ideas or suggestions?

[h22a accord]

well, i guess that the longer the stroke, the more power you can make per litre. to do this you have to to make a well balanced, strong and well assembled engine of good design which honda are renowned for doing. simple really.

[SPEEDCORE]

I'm not all that cluey with such issues but would it have something to do with the ability to produce torque?

Ie. they insist on using a longer throw of the piston in an attempt to regain as much torque as possible and increase the ability to rev by pure attention to detail in the balancing of the engine internals....

[pornstar]

yes ur both right, the stroke of a crank determines the swept area of the pistons travel, and hence therefore determines ultimately the capacity of the motor.

ie bore x stroke x no of cylinders

In that regard yes longer stroke means more capacity, more capacity means more torque so ur both right. But what im saying is, the traditional thinking is that a short stroke allows an engine to rev much easier than a long stroke. The question then is, why does honda choose the longer stroke?

[pornstar]

oh btw, H22a Accord, technically speaking what u said about the power per litre isnt right... the stroke determines how many litres the engine is in combination with the bore :)

[SPEEDCORE]

Purely for torque I guess man..... its not like a motorbike at 200kg mark, where extreamly short stroke providing pleanty of BHP but does not need torque..... Vs a car over the 1000kg mark.

That is the trade off.

[2ds]

pft b18cr is just a b16a with a stroker kit

-2ds

[Weq]

pft b18cr is just a b16a with a stroker kit

-2ds
in other words, it has torque and the b16 doesnt. Im guessing torque also, buts its very uneducated.

[SPEEDCORE]

pft b18cr is just a b16a with a stroker kit

-2ds

Beg to differ....... it has a different block height. However if you had said it was a B16B with a stroker kit than I would have said yes.

[carbine]

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.

[2ds]

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.

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

-2ds

[SPEEDCORE]

I don't see where you are comming from so can't comment on its validity.

True they are effeicient, true they are built to strict tolerances but to say that they rev this high as a consequence (to me) does not seem right to me.

If they had not been designed to rev hard, then why would they in their right mind build an engine like that is not as smooth and quiet as lets say an engine in a Honda Legend is like.

To me... they HAVE been desined to rev high as due to the lack of capacity or F/I compared with other "performance" cars, as they need to rev that high to generate the power they put out.

I read someones sig once and I have taken this into account...

The only replacement for displacement is revolutions.

[h22a accord]

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.

[pornstar]

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.

[2ds]

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

[wynode]

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?


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?

[carbine]

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

-2ds

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.

[carbine]

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)

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.

[2ds]

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.


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

[h22a accord]

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.

[wynode]

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:

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

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

[wynode]

BTW this thread belongs in Technical :)

[pornstar]

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?

[h22a accord]

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

[ginganggooly]

are we forgetting 5.0l touring car v8's that put out 500odd hp at 7500rpm or whatever they spin to??

i wouldn't be so quick to bag out the good old ls1 motor either, it's relatively light, compact and can make very, very good power. don't forget that gm actually switched from a twin cam per bank motor in the old zr1 corvette back to the pushrod setup in the z06.

have a look around for the picture of the modular 4.6l v8 from a mustang sitting next to an older 350ci gm motor... i'm guessing it was an LT1 or something. the pushrod motor was much smaller. so yes, in terms of output efficiency the pushrod motors are probably not going to be quite as sparkling as the ohc designs, but in my opinion they make up for that in terms of packaging and simplicity... i think pushrod v8's have a place in certain cars.

[Javed]

This is an awesome thread, I know this post may seem like spam, but I am just saying this should be made a sticky. You guys have taught me heaps I didn't know. Ahhh, the joys of knowledge :)

[wynode]

Ok seems i made a mistake about the S2000 not being oversquare, after doing some searching I found the following results:

S2000
Bore: 87mm
Stroke: 84

ITR (DC2R)
Bore: 81mm
Stroke: 87.2

ITR (DC5R)
Bore: 86mm
Stroke: 86

Civic Vti-R
Bore: 81mm
Stroke: 77.4

Prelude Vti-R
Bore: 87mm
Stroke: 91

Accord Type R
Bore: 87mm
Stroke: 90.7

Pulsar SSS (SR20DE)
Bore: 88mm
Stroke: 86


Thought it might be interesting just to compare (post info on some other good NA engines if you have it.

[wynode]

But still..........the DC2R is undersquare still turns out to 8,000rpm+ without any problems! :)

[ECU-MAN]

Quoted from "The Pursuit of Dreams" from the Engine First Chapter by Tamotsu Kawakami

In 1966, honda came up with another mighty machine in the RC 166, Dubbed an "extreme multi cylinder," its 250cc dohc six cylinder powerplant put out an all-conquering 60ps ans carried Mike "The bike " Hailwood to a perfect 10 out of 10 wins in the 1966 World GP Championship. Over the past 50 years, Honda has often looked at the high-revving world of motorcycles when developing new engines for its cars and vans. Its first sports car, the tiny S500 launched in 1963, had an exquisite four cylinder dohc four carburetor engine that was a natraul extension of experience gained from top level motorcycle making. The Highperformance dohc engine in the S500 caused a sensation in Japan where people marvelled at it, saying it ran like clickwork.
more dribble about F1 which I cant be ****ed typing then this
Recent Genetations Hondas with the Letter R after their name have taken Hondas egine development to even higher levels. Cars like the Integra and Civic Type R have brilliant, customed tuned four cylinder engines built for very high performance and from the outset you feel they were really ment for the track.
With a type R engine, Honda will have changed the piston shape, ligtened the conrod and valve springs , create a new oil supply line, reinforced the valve springs and balanced the crankshaft. The Intake ports and valves seats are handpolished by skilled veteran Honda technicians. this combination of high technology and hand craftwork results in a superb tuning standards. With the integra Type R, the 1797cc capacity stays the same as normal but the perfprmance level ( and sound ) are simply on a different plane. Power of 200ps at 8000 rpm means an outstanding 111ps per liter ! Maximum torque of 18.5 mkg also arrives at 7500rpm.

[wynode]

Nice info there. I think the heart of it lies in Honda's history starting off with motorbike engines and that is what has filtered down to the legendary B-series engines. Afterall that is where VTEC was developed :)

Ohh and for anyone who's doing more reading, you can't go past this article (http://www.hondatuningmagazine.com/tech/0203ht_killerb) on the legendary B-series

[Mateoo]

Awesome thread :thumbsup:
i also do agree the theory behind the longer stroke and smaller bore is less resistance to force
having smaller componets eg , pistons and a longer throw would allow these small displacement motors to spin to high rpms with ease and less strain than a bigger bore , short throw motor

PS. was also thinking bigger bore pistons would mean more surface area touching clyinder sleeves = more friction ?

[toE]

......the S2000 not being oversquare......

I don't get what you mean here Win.

Are you talking about the shape of a piston err...head? Or something else?

Any pics/diagrams to go along with what you have said? I understand better with illustrations. :o

[wynode]

I don't get what you mean here Win.

Are you talking about the shape of a piston err...head? Or something else?

Any pics/diagrams to go along with what you have said? I understand better with illustrations. :o
An engine that is perfectly square has its bore=stroke
Over square --> Bore > Stroke
Under square --> Stroke > Bore
:)

[2ds]

i assume they gave the ITR engine a longer stroke because they figured it would be more reliable to stroke it to get more power than to raise the redline another 1.5krpm

-2ds

[ProECU]

What tha?

they actually decreased the stroke, increased the rod length compared to the B18A/B motors. Increased rod length results in a more stable engine at high rpm.




i assume they gave the ITR engine a longer stroke because they figured it would be more reliable to stroke it to get more power than to raise the redline another 1.5krpm

-2ds

[ProECU]

Larger diameter doesnt always mean more surface area of contact between sleeves & pistons. Honda are known to alter the shape of the piston skirts and make use of a "ribbed" type design for the area above the ring lands on the piston. For those who have seen a type-R piston, Im sure they would concur.

Even without these design improvements, the increased friction would not be a major factor which would lead to motor failure.
The problem is with side force (thrust) of the rod/piston through the cylinder walls at an angle.
You often see cylinders crack mid-way, this is the reason.



Awesome thread :thumbsup:
i also do agree the theory behind the longer stroke and smaller bore is less resistance to force
having smaller componets eg , pistons and a longer throw would allow these small displacement motors to spin to high rpms with ease and less strain than a bigger bore , short throw motor

PS. was also thinking bigger bore pistons would mean more surface area touching clyinder sleeves = more friction ?

[2ds]

What tha?

they actually decreased the stroke, increased the rod length compared to the B18A/B motors. Increased rod length results in a more stable engine at high rpm.

i thought the b18cr was more closely based on the b16b than the b18a/b motors ?

-2ds

[wynode]

The head, yes

[crx_16x]

Nice info there. I think the heart of it lies in Honda's history starting off with motorbike engines and that is what has filtered down to the legendary B-series engines. Afterall that is where VTEC was developed :)

Ohh and for anyone who's doing more reading, you can't go past this article (http://www.hondatuningmagazine.com/tech/0203ht_killerb) on the legendary B-series

Are you forgetting the C30???
The NSX was released in 89 as well as the B16a.