Does anyone know the correct rod length and r/s ratio for the b16b?

 

I think the rod length is 5.620, but do not have my notes here. 1.85 R/S not the (perfect) 1.77 but what does Honda know.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DonF &raquo;</TD></TR><TR><TD CLASS="quote">I think the rod length is 5.620, but do not have my notes here. 1.85 R/S not the (perfect) 1.77 but what does Honda know. </TD></TR></TABLE>


This is a good point. If 1.75:1 is "perfect" and the b16a's 1.74:1 comes damn close, why did honda design the b16b (the nastiest b series engine in terms of HP/Liter) around a b18 deck height? I think the obvious answer is to stuff in a longer rod, but then that defeats the H-T argument that 1.75:1 is perfect. So lets hear it, techies....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LsVtec92Hatch &raquo;</TD></TR><TR><TD CLASS="quote">


This is a good point. If 1.75:1 is "perfect" and the b16a's 1.74:1 comes damn close, why did honda design the b16b (the nastiest b series engine in terms of HP/Liter) around a b18 deck height? I think the obvious answer is to stuff in a longer rod, but then that defeats the H-T argument that 1.75:1 is perfect. So lets hear it, techies....</TD></TR></TABLE>

The real answer? There is no perfect rod/stroke ratio. It's like saying "what is the perfect final drive?" It all depends on the car, and what it's used for.

 

So if it all depends on what its used for, what would be a good application for a low R/S ratio engine?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LsVtec92Hatch &raquo;</TD></TR><TR><TD CLASS="quote">So if it all depends on what its used for, what would be a good application for a low R/S ratio engine?</TD></TR></TABLE>

For big big strokes and going fast at the drag strip

 

I know this, but im asking for the "whys" behind it...

 

What I was thinking, is that is you look at sportbikes they usually have r/s ratios above 2:1 (the nissan vq30 in the older maximas had a r/s ratio of @ 2:1 which contributed to its smoothness) --and they rev up to 14,000-15,000. So I would think that for most purposes 1.75:1 is probably "ideal", but for durability at really high revs, a high r/s ratio is better. I am quite sure F1 cars are in the 2.2-2.3:1 area. It would also be interesting to sleeve a b16b (or a b18c block with b16 crank) to like 86-87mm, and use the nastiest cams and headwork you could get your hands on--and my ideal would be to put Lectron carbs on this motor. So you would have an 1830cc motor, and if you could have peak power at say 10,500--I wouldn't be surprised making 325 crank hp . Are any of the pro all motor cars making power density similar to this?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LsVtec92Hatch &raquo;</TD></TR><TR><TD CLASS="quote">I know this, but im asking for the "whys" behind it...</TD></TR></TABLE>

http://www.stahlheaders.com/Lit_Rod%20Length.htm

Good article to read.

 

I know most of the reasoning behind the "why's" already, i was just hoping to turn this into a useful read, maybe for someone in the future, theres just been too much **** floating around these forums lately, i felt the need to start a somewhat intelligent conversation.

 

****** 1.75 is not "ideal" it is an old wives tale, from some one who does not know. Bore, stroke, cams, induction system, rev range, tells you what is "ideal". Not some website. Go on E-bay and look up used rods for sale from Yates they are 6.2,6.3, 6.4, and 6.5 in length. Cranks are 88-90mm stroke.

 

So in your opinion Don F, does bore and stroke combo tell you more about an engine and its useable rev range, or just its displacement overall? For example...

Two engines.
1 is 84x89
2 is 87x84

Will they perform similar?

 

Induction, head flow will tell me more. Larger bore, larger valves, more air , more RPM's. Same size motors and # of cylinders, the longer the stroke, the VE and BMEP will be created at a lower RPM do to velocity and cylinder filing capabalitys. Short stroke, larger bore, bigger valves (bore restricted) will have the VE and BMEP at a higher RPM. The more RPM's the higher the R/S . Old math it's in Smokey's or Keith Duckworth's stuff. Short R/S ratios are going to make power lower so you are looking at cam timing of 98-100 degree centerlines. As the ratio increases you would widen the center lines. Same cams, same head, same compression, B-16a VS B16b the cam timing would be different. I will let you figure it out.