I was looking at some dyno sheets from around the web trying to figure out if I want to keep my b16b or sell it. Of course the torque in that motor is nada and the torque in the 1.8 GSR motor is awesome.

Anyways, what seemed to appear in my research was that the b16b has about a 15% drive train loss and the b18c had about a 10% loss. So it dawned on me that possibly the more torque you have the less horse power drain.

Yeah I realize theres a lot about dynos and tuners that can make a difference but it looks obvious.

What do you all think?

 

Nope, it doesn't work that way, horsepower output is derived directly from torque (which is what a dyno actually measures). Drivetrain losses are a percentage of total power output, the only thing that can greatly skew the numbers is dynoing the car in lower gears (the higher the gear you dyno in, the greater the power output looks due to what's basically a decrease in inertial loading as seen by the dyno).

 

If horsepower is derived directly from torque wouldn't the percentage of loss be less if your motor had more torque then?

PLEASE hang in there with me, I am sure its just what I want to see.

Btw how much whp do you think a gsr (170 hp @ flywheel) makes?

 

The percentage of loss through a specific drivetrain can be expressed as a percentage of torque drop from the flywheel to the tire contact patch, so no. 15% is 15%, regardless of whether it's out of 150 lb/ft or 1500 lb/ft.

From what I've seen a stock GSR generally puts down about 140hp to the wheels. But any dyno comparisons you make will be questionable since the dyno calibration and other such parameters during the test are very fluid (and you're almost certainly comparing data from various locations, times and vehicles).


If you have a B16B and are looking for more torque, you can always drop in the B18C crank and rods. Or you can move to forced induction. To put it plainly, there's no reason to get rid of such a rare and sought after motor when all the potential any Honda motor has ever had from the factory is just lying around in your engine bay.


[Modified by texan, 3:01 AM 2/7/2003]

 

Thanks Texan. Looks like that put it in to more perspective for me. Perhaps I will drop in the motor then at a later date (next year) swap out the crank and rods from a b18.

From what I gather swapping the crank and rods out will boost my torque (probably from pure displacement growth) but will lower my comp. ratio.

True?

 

No, it will increase your compression ratio. Chamber volume will remain the same (if you can and do use the same pistons), but swept volume (displacement) will increase. The difference in increase will be 12.7% (449.3cc vs. 398.8cc), so your 10.8:1 B16B compression will become 12.2:1.

 

great explanation for this phenomenon...few people understand exactly how a dyno works...and how final drive and gearing affects measureable horsepower and torque.

 

Well I dont think I would want to run those kind of numbers on comp. ratios.
What comp. should I drop down to to retain a 10.8:1 ratio?

And would this be ruining the effect of the b16b motor?

By the way Texan I guess I may have been influenced by some post on this board, like "b16b are just for jdm crazy guys and dont really offer much"

I realize that the b16b is a great motor loaded with potential...Im kinda a research hound and try not to let these boards influence my thoughts but rather a place to gather information.

So for autoxing and the occasional drag (possibly with some juice) this is the motor?
Thanks again man!

 

If you are serious about NA power, I wouldn't go below 11.5:1 compression. Running premium with a lightly prepped chamber, and perhaps a slightly more aggressive cam profile than the CTR's, and you won't have any detonation problems. A slightly thicker head gasket will do the trick, if knew what the sotck gasket thickness was I could calculate what size gasket you need.

The B16B motor is fantastic, BUT it is still a 1.6L NA 4 cylinder. Very few people on the planet would consider that a serious performance motor just from the basic specs, and in some respects they are right. It definitely depends upon the chassis it's in (mostly vehicle weight concerns) as to how well it will perform, as low torque motors are just killed by heavy curb weights. Bumping the displacement just to 1.8L brings around a 12.5% jump in torque output, which goes a long way to making the engine perform better. Since you already have a tall deck, this can be accomplished without the geometry concerns one would have on a B16A.

Personally I think these motors only shine when turbocharged, as they are perfect candidates for it (other than the stock pistons and rods, which can still live a happy life as long as tuned properly). NA just isn't going to take you very far on such a small engine in an already very high state of tune, but your goals are up to you here. Hope this helps, peace.

 

Thanks man, Case closed.

 

so whatcha gonna do?

 

are you certain? I was under the impression that drivetrain loss for a given system is a specific figure rather than a percentage, thus a increase in total torque would decrease the % of drivetrain loss (well with some positive correlation between increasing torque and increasing drivetrain loss, but not a direct correlation). Isn't there only so much that can be loss through friction between the engine and wheels? say a 150ft-lb producing motor with a Y drivetrain system loses X amount, and if you boost it to 300ft-lb, the loss would not be 2X the amount, but a number in betwee, thus the % of loss is less since you increased torque production more than drivetrain loss?

 

You are correct TypSH, it's not that simple. Nowhere near that simple in fact. If you get into the real physics behind it, it's so complicated that estimating power loss % through a given drivetrain vs. engine power output is hopeless for non Einsteins like us (or at least me ).

Consider for a moment that it depends first on the type of dyno you are on. An engine dyno is generally operated by balancing engine power output against braking force, and as such is steady state in operation and therefore doesn't take into account any real inertial loading. On the other end of the spectrum you have Dynojets, which take into account every type of inertial loading into their output numbers. Imagine that doubling power output will equal an approximate doubling of inertial loading in any given gear, since the vehicle is now able to accelerate the rollers twice as fast (and hence it's entire drivetrain speeds up twice as fast). Of course the Dynojet will skew those output numbers accordingly, but the engine dyno will not. In essence, doubling your power output numbers on a Dynojet requires a greater increase in actual engine power than doubling your engine dyno numbers.

Or consider that friction actually does increase with power output. The harder the pistons are forced downward during the power stroke, the higher the thrust loads become and also the more friction encountered by the rings against the bore. Likewise an attendant increase in rod bearing friction is encountered, as well as crank distortion and therefore crank bearing friction. Here's our primary reason that increased power output necessitates increased oil pressure (to keep the thin layer of oil from being squeezed away from bearing surfaces under increased pressure), and yet another thing to consider when factoring in frictional losses. Is this frictional increase linear? No, friction increases exponentially with increased force. A little force equals almost nothing in friction, but doubling a great deal of force might be a recipe for exceeding metalurgy strength.

Also consider that as power increases become larger, verious drivetrain parts must be replaced. Those parts are about as likely to generate equal friciton, inertial loading, cylinder sealing ability and thermal efficiency vs. their stock counterparts as I am to jump up and spontaneously fly away with nothing more than gastro-intestinal prowess. So here is just another log on the fire of complication.

The point is that calculating % loss through a drivetrain is so hopeless as we get away from stock setups and power outputs, that the simplest and most effective assumption is to assume nothing has really changed all that much. This may be naive, but it is almost certain to put you on the pessimistic side of actual power the the wheels, especially if one is measuring output on a chassis dyno. I've learned that being pleasantly surprised by power output is much more fun than being let down, so in the interest of seeing happy people and keeping my own long, drawn out opinions to myself (too late), I sometimes just suggest the obvious and simple answers.

 

Damn, Heres an idea...b18c gsr motor with 10.0:1 comp. ratio, replace with say 10.8:1 pistons. Much more power or not worth it?

Thanks man, Dan