Big throttle bodies don't work that well on mouse motors

[Admiral Akbar]

So, Max's statement about velosity can't be correct.  How else can the VE numbers be so high?

What do you mean here?? What part about velocity?

I think that we can get a good discussion going..

Max

[hrdtail78]

".. and there may be something to velocity in the intake tract.."  First post

"The interesting thing about this is that velocity seems to make little or no difference in overall performance."  post 123

Calling out the post number so I am not taking this out of context.

Forced induction isn't fair to let play in this game.  Wasn't trying to trick.  Just backing my point.  A little smart azz maybe.

On Bob's example.  I blame velocity that the cylinders are getting filled as well as they are.  I speculate that a larger TB would raise top end HP, but what would it do to the area under the curve?  Again only if the TB is a restriction.

Max, You have also made the statement that a Carb that flow slightly more than the heads would be the best choice.  I agree w/ this one. 

At one time bigger was always better in theory.  Valves, ports, carbs, cams, plenums, and how it was found a little smaller the better.  Now us that like to tinker are playing with TB's, probably on baggers non the less.

I understand the differences between carb and FI, but some of the same principles do apply.

[Don D]

On Bob's example.  I blame velocity that the cylinders are getting filled as well as they are

I would agree, but credit would not be for or against the TB. It is a neutral conduit doing it's job and not a constraint. Those heads are sleepers.

[Admiral Akbar]

".. and there may be something to velocity in the intake tract.."  First post

"The interesting thing about this is that velocity seems to make little or no difference in overall performance."  post 123

Calling out the post number so I am not taking this out of context.

Forced induction isn't fair to let play in this game.  Wasn't trying to trick.  Just backing my point.  A little smart azz maybe.

Hey I though I was the only one that could be a smart azz?!??!? 

Just kidding.. My thoughts about velocity are still up in the air.. I do seemed to have found a case where it seems to not make much difference. The purpose of the test was see what the change were to a reasonably high performance motor when going trying both ends of the spectrum in TB size.. These 2 TB flowed about the same with no exit stack on the bench.. While I can't test the current TB on the bench, I've noticed a significant increase in flow on the WT57 with an exit stack. Since a cylinder head port is more than likely a split in the difference between both no exit stack and a good 2 inch exit stack, I would expect that the WT does flow a little more. And the dyno shows it up top. I think it is significant.. The 1 fp on the mid ranges is not..

Parts of the point of this was to validate intake flow/velocity effects on this build. Since it is not significant, Back to the exhaust.

BTW,

Installing a better exhaust may change the results of the big TB / Small TB experiment and it may be worth repeating later.

I suspect the the difference in length of the pipes is part of the problem.. Back to a 2 into 1..

Max

[mayor]

I suspect the the difference in length of the pipes is part of the problem.. Back to a 2 into 1..

Max

so you don't buy into the notion that scavenging tendencies of a 2 into 1's are why they produce higher numbers.....it's all about equalizing pipe length? 

there's one way to test that notion....how about Bassani TD's with that tq loop thingy?   


 

[Don D]

Installing a better exhaust may change the results of the big TB / Small TB experiment and it may be worth repeating later.

Excellent point, and what I have been saying about having the ability to leverage exhaust from the chamber all the way to the tip of the pipe. That means the port, the valve, and the pipe. We don't have the real estate to get that carried away on the intake side, just have to be sure it is not a restriction and more issues enter with carbed bikes besides just airflow.
As far as the Bassani, nope been there and done that once. The stock headpipes worked better.

[FLTRI]

As far as the Bassani, nope been there and done that once. The stock headpipes worked better.

Yep, my results as well.
Bob

[Admiral Akbar]

As far as the Bassani, nope been there and done that once. The stock headpipes worked better.

Yep, my results as well.
Bob

What about the Rage?

Max

[Don D]

 
Only messed with a few that had the "quiet" baffle. No dice. The pipe is not stepped and the baffle was very restrictive. Unless someone gave you one....
If I had one I would make a new baffle and fit the back with a trap. I already did one of those for a guy.

[Admiral Akbar]

Thanks Don,

I've got a Trapp 2 into 1 for LSD, that I can mod to fit.. Either that or the LSR.. Max

[PanHeadRed]

Have you got an exhaust pressure gage?

Rumor has it for every 1/2 lb of back pressure you loose 1 -2 HP.

By the time you hang enough discs on that ST you will be using all thread to hold um.

If your real goal is to hit 120 HP from a 95" T/C you better accept the fact that it's going to be loud, and theres a real good chance your not going to have 2 mufflers on it.

[Admiral Akbar]

If your real goal is to hit 120 HP from a 95" T/C you better accept the fact that it's going to be loud, and theres a real good chance your not going to have 2 mufflers on it.

It could have 2 mufflers on it, they just both have to be on the right side.. 

You are right though.. I'll try the LSR again.. Max

[PanHeadRed]

Try putting the muffler on 1st then the head pipe, experiment with "reverse flow" technology, or you could switch the TB and muffler and experiment with "inverted flow" technology.....I never had much luck with either technology, but then I never had your skills. 

Assuming your not "choked" or suffering severe reversion, the key to unlocking an engine is always the exhaust system, when you find it you will be amazed. Every time I have found it it has been dumb luck, I just keep hanging systems, and eventually when you hit the right one your test ride will be....WOW!

Or you can  merge the head pipes (12.5 deg for V-Twins?) install a gage, get pressure as close to zero as possible, and start playing with the pipe lengths (collector, muffler body etc). To me, that sounds more like your style.

[hrdtail78]

12.5 for v-twins....   Hang the LSR pipe.

Where go you take the reading?

[PanHeadRed]

O2 bung, or as close to the engine as possible.

[Admiral Akbar]

For those who say the stock TB isn't good for over say 105hp, please refer to this, done today:
http://harleytechtalk.com/htt/index.php/topic,22385.0.html
Bob

It's definitely not hard for them to hit 110 with a 95..  120 on a high compression 107 motor.. Kind of like the mythical girl that can suck a golf ball through a garden hose..    Max

[Ken R]

There are some really knowledgeable people on this forum.  I think maybe they're all in this thread. . . . .or maybe more are lurking.  I wish I understood half of the posts.  So much to learn, so little time.

Maybe this would be a good place to thank 'em all for the help and education I've gotten over the years. 

Ken

[11.7to1]

Velocity, momentum and inertia go hand in hand. You can't fill what isn't evacuated.

[Admiral Akbar]

Velocity, momentum and inertia go hand in hand. You can't fill what isn't evacuated.

Are you telling us that everything sucks?  Max

[Deye76]

Velocity, momentum and inertia go hand in hand. You can't fill what isn't evacuated.

Are you telling us that everything sucks?  Max

Along with a bang and a blow

[skyhook]

cant believe such smart fella as you still chasin dyno numbers

my latest numbers suck and bike never ran better

was fun goin to panama city then atlanta  and back in 2.5 days on a sportharley

really like open cap supertrapp

engine works well long as i dont snatch throttle too soon

[Admiral Akbar]

cant believe such smart fella as you still chasin dyno numbers

Do you mean me??    Actually I'm not chasing dyno numbers, I'm chasin' performance.. and learning something in the process... Now every time I post dyno numbers for Red about has a "Potty mouth".... So far my theories have been good.. Or they seem so.. The poor bike is torn down again for another set of cams...

Max

[Don D]

What's in the pipeline now?

[Admiral Akbar]

Crane H290.. Compression might be too high though.. May have to pull the top end and lower the CR.. I do think I'm getting a reasonable handle on tuning the Tmax..

Max

[Don D]

All pretty interesting stuff.
I remember that cam.
Works better at the lower side of 10/1. You can pick up 2cc by laying the chamber back .125 on each side. No issues doing that