Crank Question ls or type r??

[K2e2vin]

Makes you wonder why Honda went with 87.2mm instead of just sticking with 89mm; unless there's a 1.8l class(the B18A/B is about 34cc over 1.8, while the B18C is 3cc under 1.8)

 

[alterdcreations]

factory redline of the gsr and itr are higher than b18a/b but it also has to do with valve train/ cylinder head design(bigger valves) then the oiling system/pump,squirters and i thing the gsr/itr bearing are tri metal(factory issue)

 

[alterdcreations]

i think its alot more than just the stroke

 

[alterdcreations]

Something else to think about, in general terms, is that a piston will be farther down the bore with a short stroke at any given crank angle than it will be with a longer stroke. Which makes it more efficient in pulling in air. Don't forget to look past the mechanical aspects.

Isn't that only true for the top 1/2 of the stroke.?
longer stroke means that the piston travels further down the cylinder in the same amout of time as the shorter stroke. that why the engine tends to outrun the flame in extreme cases.
but i might be wrong

 

[phunky.buddha]

Something else to think about, in general terms, is that a piston will be farther down the bore with a short stroke at any given crank angle than it will be with a longer stroke. Which makes it more efficient in pulling in air. Don't forget to look past the mechanical aspects.

Huh? That doesn't make any sense. A B18A/B piston will be lower in the bore at the bottom of the stroke than a B16A's piston.

 

[phunky.buddha]

...in general terms...

No, not true in any engine. Longer stroke = lower in the bore at bottom dead center no matter what.

 

[LateApex31]

It doesn't change the physical dimension of the sleeve, however the 'swept area' of the piston does hange with stroke. Technically, this is what one is referring to as 'stroke', or how far the piston travels from TDC to BDC.

 

[MikeBergy]

Shorter stroke = lower piston speed = less vacuum on the intake stroke = lower air flow velocity = lower volumetric efficiency at higher rpms....but here's the catch: ALL other things being equal, and assuming that you are not choking the flow at the valves. You are comparing crank stroke and its affect on engine performance, not how the engine is going to perform on the whole. Once you bring things like bore, R/S ratio, etc into the mix, you have to look at things parametrically.

The guy wanted to know about what crank to use - I say go for an LS crank. If you build it right, it WILL outperform an identically built engine using a GSR/ITR crank.


Blanco - at BDC a longer stroked setup WILL sit physically lower than a shorter stroke setup RELATIVE to the deck; it will sit lower by exactly the amount of difference between the strokes. Rod length has nothing to do with anything except for setting the deck height.

 

[phunky.buddha]

to the Bergy

 

[alterdcreations]

Isn't that only true for the top 1/2 of the stroke.?
longer stroke means that the piston travels further down the cylinder in the same amout of time as the shorter stroke. that why the engine tends to outrun the flame in extreme cases.
but i might be wrong

not wrong.
but i knew that all along

 

[alterdcreations]

You are correct, ultimately the short stroke motor will hold together at a bit higher RPMs. But we are talking 10,569 RPMs vs 10,256 RPMs (not any exact figures here, simply for demonstrational purposes). Ultimately, for a street motor, the longer stroke motor makes more power and torque at a lower RPM with zero sacrifice of top end power.

Take a B16A vs a B18C1 for example. Same bore, similar compression, 10 more HP and 20 more ft lb of torque for a very small increase in stroke and exact same revability.

Forums are open to anybody with a idea or opinion. feel free to respectfully speak your mind and be open to other peoples ideas also.
all we are talking about is

The GSR actually has longer rods than the B16, but only by a few mm. The 89m stroke block has rods that are only .9mm shorter than the GSR and ITR. If your argument is between the 87.2mm stroke and the 89mm stroke, you're really just splitting hairs. The difference in rod/stroke ratio is less than .04- just under 1.58:1 for the GSR/ITR and just over 1.54 for the non-VTEC B18.

Shorter stroke engines will generally have flatter torque curves, but the flow of the B18 engines are such that you can still have a really awesome pancake like torque curve and still rev/breathe to the limits of a worked head.

Now comparing the B18C to the B18A/B in terms of stroke... just pick the B18A/B crank if you have the option.

seem like every body has alot to say.
very good info

 

[alterdcreations]

Something else to think about, in general terms, is that a piston will be farther down the bore with a short stroke at any given crank angle than it will be with a longer stroke. Which makes it more efficient in pulling in air. Don't forget to look past the mechanical aspects.

it's just reverse.
live and learn
please lets get along.

if i were building that engine i would use the ls crank and sell that type-R crank for alot of money for which i would use to finish the short block(i know sombody will pay top dollar for it)

 

[MikeBergy]

Makes me wonder why almost every professional race team in the world runs a short stroke and large bore for high reving application, then. Or why the top builders in the WD-40 Shoot Out all chose the GSR crank for their builds except for Rocket who gave up on trying to build a high reving 95mm stroke.

Most professional race teams are running in events that limit displacement, which in turn limits power output that might result from displacement alone. SO they go the opposite extreme route and shorten the stroke such that they can rev to 15k all day long.
Power = Energy per unit time. So, if you are limited to displacement, but not limited in power, what do you suppose teams/engineers want to optimize? They want to flow as much air through their engine as possible with their given displacement - The best answer is just to rev the piss out of it. This is obviously not going to work as a streetable setup, because you have very poor low end performance.

The GSR crank was probably utilized not only for a slightly better revability (it does have an advantage in that area), but also it is likely because the gsr bottom end has a stock girdle for support, and the LS does not. I am not familiar with the WD-40 rules, but it is a possible reason.

 

[alterdcreations]

I saw this today and thought the creator of this post (youndlord94) and everybody else could get more info and veiw other opinions on this topic.
Honda-Tech.com: LS crank or Gsr crank in b18c1 block?
enjoy!