B20 myths.

[96Civ]

You seem to lead off with every question I have. Would someone helpful or with more experience please answer my questions? Thank you.

[andera]

Originally Posted by 96Civ

You seem to lead off with every question I have. Would someone helpful or with more experience please answer my questions? Thank you.

wat are your questions? maybe its jsut a bad day for me and im just missing them, or they're just not clearly stated...

[96Civ]

Originally Posted by 96Civ

Would you aim for more RPM's, hence a near perfect R/S Ratio because more RPM's is more work done, right? Would that mean we all should be aiming for a motor that can rev higher because there will be more power gains? I.E. More torque and horsepower at 10k than 5k?

How would setting up a turbo to boost at 5k compair to 10k? What are the advantages and disadvantages?

What would your powerband look like up there? You would get more horsepower but your torque would take the beating? What gains would I see if I went for a higher powerband and what disadvantages would there be.

[crxtacy]

if you wanted your powerband in higher rpms, couldnt you just go with skunk 2 or toda cams with valves, valve springs, retainers, etc. that would put your powerband up to around 9k. or woudl the bottom end of a b16 not take that?

[96Civ]

To answer your question crxtacy, the only part of the engine that would need to handle high reving would be the cylinder walls, pistons and the crank. You see, the longer your rods are, the more stress you put on your cylinder walls because your crank never pushes the piston strait up. The crank moves in a circle and the end of the rod that is connected to the crank is what connects the power from the piston to the crank. The crank never pushes strait up... ever. The only time they are all alligned are when the piston is at its peak height or at the bottom of its decend.

I guess you can say that the rod is what converts the up and down power into a circular motion which makes your motor turn. I believe rotary is more effective at the transer.

So basicly what I have learned through searching. No help from other people on the board. *cough* andera *cough* Is that shorter engines are the only good engines for reving high simply because the R/S ratio is better. The piston doesn't have to move up or down as far therefor you can get more RPM's safer.

But because the rods are so short, you can say goodbye to your torque. This is a trick of motorcycles. Especially sport bikes. They are made to rev high because they need more horses than torque to push those 400lb. monsters. Cars need more torque to push their weight. Thats why they can get away with it.

So indi cars are made to rev high because they are lightweight and aerodynamic. They can do fine with a little less torque. But racing with heavier cars like NASCAR, they CAN rev high, but not as high. They need that precious torque to move them along. They are not as aerodynamic so thats where drafting comes in.

So that said... some ricers think more horsepower is more important than torque... WELL, it WOULD be if your car was about 800 pounds lighter! Building your engines to rev higher WILL give you more horses, but will it make you go faster? Depends on how badly your car needed that torque.

THATS why you plan ahead. Hey cool, I learned something new today.

[crxtacy]

thansk for the info 96civ. figured i would ask since everyone is talking about changing cranks and rods and shit for higher rpms. i dont understand why you wouldnt get a b16 and put upgraded cams and head parts on it for like a 9k rpm redline. the entire head would be built for that.

i understand the stress being on the cylinder walls, but i dont see how 800-1000 extra rpms could fuck it up bad since the top end would be built for it. your not changing any of the internals of th engine

[96Civ]

All depends on if your valves and walls can take it. Long rods=more stress=less rpm's. If you don't obey the red line of your engine, chances are it won't last as long. Pure and simple.

Here are the B20, 18 and 16 specs...
http://hybrid2.honda-perf.org/tech/b20/b20tech.html

You will see the B16 has more horsepower, but now you know why it does, and you will know why it won't win the race.

[crxtacy]

uh.. y wont it win the race. the rod stroke is damn near perfect. yes it has the most horse power and the smalled amount of torque, but with the short geared tranny, for it to stay in its power band isnt really hard.

between the b20, vs the b16, i believe its a drivers race.

my question is though, with a skunk 2 stage 2 cam set and vavles, retainers, and springs, a head ment for 9k rpms and a top end to take it, will a stock b16 bottom end take it, i know the good rod stroke ratio is ment for a high reving engine, but is the 2nd get b16 bottom end good enough to take a couple extra hundred rpms.

yeah have givin me alot of info which i am thankful for. dont mind gaining knew knowledge every day.

[96Civ]

Well, the b16 has a R/S of 1.74. That is better than all the other leading engines, but you really do have to upgrade the engine a whole lot more than just what your talking about. If your reving that high, your going to be making a LOT more heat... so at that point its not about breaking your engine, its about warping it. I would think you would need forged pistons and stronger cylinder walls at the least.

You have to really think about the R/S Hype thats going on all the time. If you think about it, there is no perfect R/S because your rod will be pushing your piston into your walls in each and every stroke except at the top and bottom of its travel which unfortinately is when your creating no power because the piston isn't moving! It turns around and gets shoved into the wall again and again, except if your reving twice as much, your creating twice as much stress on the engine. Heat will rise and walls will warp.

Now I'm sure you can rev high safely, but you do need to fix up your bottom end to handle the additional stress and heat. If I wanted my engine to last, the least I would do is a resleeve with forged pistons, and maybe a little lighter crank.

I would just keep in mind that people that do take real advantage of a high rev limit have short v8's and v12's because they will still have torque to back up all that HP. A 4 cylinder is just not as good at this IMO because people will be passing you up every time because you dont have the power to back it up. Hell, indy cars have 24 cylinders and a really high rev limit and can obviously tear anyone a new one.

Also, keep in mind:

Profesional drag racers that have a really high powerband don't measure how long their engine lasts in miles... they measure in minutes.

[96Civ]

I also want to add that I have a Nitro RC Car, and it can rev to about 45k. The reason for that is because the rod is only I think... an inch long. RC Cars dont need much torque to push 3 lbs.

[96Civ]

I also found a dyno of a b16. It appears to be stock. Notice where the torque falls off?

They shut it down at redline 8100 RPM's. But notice the torque peaks at about 6200 and then begins to fall down? Horsepower keeps going up, and your just replacing horses for torque.

[96Civ]

And heres the B20.

They look similar, but the extra .4L of displacement gives it that extra torque while the 1.6L doesnt have more torque, but more horsepower and can rev higher.

[kris]

And here is both put together.

[96Civ]

Now THATS NICE! Its my dream to get a B20 with a B16 head, resleeve, forged pistions, just everything modified... and then turbo it with 30+psi. Simply bad-a$$!

[crxtacy]

how much am i looking at for resleeving? or if i didnt change the rpms, how much power would i need before i resleeve?