awd eats hp>!

 

Port size, Port contours, valve angles all play as much a role as total flow. B series heads flow the same amount as a stock small block Chevy. I have seen mildly worked B series heads flow even more, not to mention something like a full race head.

I have always attributed it to the fact that Honda engineered their engines to be ultra high specific output NA first (high VE), then they get turbocharged whereas Mitsu engineered the motor to be a high specific output turbocharged first (lower VE with the turbo making up the difference). BMW motors are the same way. Look at an S54 motor both NA and turbocharged and the amount of gains are significant.

This discussion is frankly as old as the internet.

 

It's not only about VE, but rather where in the rpm range VE is maximized. The higher peak VE occurs, the more hp is generated, and the Hondas appear to be designed with that specifically in mind (unlike the 4G63).

 

this part might be related to an n/a car being turbo charged. they're not cooled to make 400hp.

 

Very good point Ted. You might have repeated that for my benefit (havent read all of this thread yet), but when you take an engine that is designed to maximise power per unit of displacement it always ends up being a high winder. Peak torque higher than crossover, redline in the high 7's or above, etc. Then take a motor that was designed to be a torquey rally motor and compare. Though its not a direct cross, if you have engine A that makes peak power at 6K and engine B that makes peak power at 8K, at identical variables (turbo, boost, displacement,etc.) engine B will always make more power.

 

Well, turbo diesel engines with long strokes and short rods generate high VE at very low rpm, so the degreee of VE isn't directly rpm dependent. Where max VE occurs is all in the mechanical tuning of the engine, and it seems as though Honda B-series sizes everything to push max VE upward in the powerband as opposed to a 4G63.

 

Sorry but what is VE...

This has been an interesting thread with a wealth of info but now you are losing me with this VE?

WADAD

 

VE (Volumetric Efficiency) is basically how much air mass the engine can pack into the cylinders at a given rpm, with respect to the engine's displacement. The greater the VE at a given rpm, the more torque is made. VE is typically expressed as 0-100%, where 100% for a 2.0L engine means the engine is packing a perfect 2.0L worth of air mass per every two revolutions at that rpm.

'Tuned' parts, such as cams, manifolds, head ports, etc., have an effect on where in the rpm range VE is maximized. In a normally aspirated engine, the torque curve is basically VE, so it's easy enough to see what's happening. It's a little more tricky to see it correctly in a turbo engine.

Since hp is simply how fast (rpm) torque is being applied, the higher in the rpm range we tune for best VE, the more hp we make. The downside is that the higher in the rpm range max VE occurs, the less it is at low rpm, which makes the motor sluggish and unresponsive at low revs.

 

We all know that a turbo is one of the key elements that change VE, so on that note I have personally ridden in a honda with a big 16g and I tell you that thing has its peak torque looking similar to that of a dsm on the dynograph and it has about the same sweetspot when driving the car also. If you think about it the motors are very similar since they have similar rod stroke ratios. The only reason we have so much mid range is due to the turbo at this point and we alll know if you change the turbo the midrange will change. Most honda guys go with a huge turbo that they barely have enough displacement to spool.

 

Perhaps, but one has to consider that a 16G doesn't flow enough air mass to expose the limits of either at higher rpm. AFAIK, this discussion pertains primarily to the difference in power using larger turbos, where the mass air limits/efficiency of physical components (e.g. ports) are tested.

 

all this talk has lead me to thnk that if honda would build turbo engines that are cooled to make turbo power... they would make some of the best high output engines possible. this of course would require some chassis design fundamentals to be changed... like awd, rwd

 

i don’t think Honda engine have cooling problems when turboed. aluminum block, open deck and oil squirters all aid in cooling. Most boosted Honda run half size radiator due to limited space and don’t have cooling problems. Honda’s new turbo K23 from the RDX is base on the K24 and I don’t think they changed much in the aspect of cooling.

 

Hhaha yea it would definitely be a 2 wheeler peeler. On a side note honda has already come out with a boosted k series motor, 2.3 liter turbo in one of the new suv models that acura carries. I think it is called acura rdx or something

http://www.acura.com/index.aspx?init...periencetheRDX

 

i'm not referring to an overheating i'm talkin' about a fundamental design where n/a engines not built for turboeing may reach some sort of heat threshold sooner and therefore won't be able to be tuned with more boost + timing.

 

yeah i think we all know about this one... and it's of course every honda fan's wet dream finally half realized...