Head flow testing.

[Hobot]

i've crashed in utralight so appreciate harmonic insights from real pilots webby.
The flow details the Gods are listing make my head spin, which I like.

On mc-engine list some have success of intake and exhaust porting using Devon or these producets, with some care to texture or stack so it stays in place, some by making a whole ring of epoxy around the port.
http://www.belzona.com/prod1k.aspx

Water can be sprayed into exhaust system to change its harmonics, especially in 2 strokes, don't know how it'd apply to 4 strokes. The main reason for the 'puter revolution in elite bikes is to make such power and rpm the torque ram resonance comes and goes over a few hundred rpm, to upset traction when leaned or pop unintended wheelie waiting for power to respond to throttle.

I've come across canisters attached between manifold tracts, same way dual carbs have balance tube, to act as Helmholtz resonator to tune sonics on too short intakes. Don't know if applies to Nortons twins.

Both my Combat's had extra piston kick in ~6800 rpm. Over big CHO head on 750 was kinda a bog in response till over 6000 compared to standard head, 2S cam. I hope it might be give good flow response on a 920 before injurious rpms. I suspect it may limit top end power but I don't care d/t Drouin way around that.

Too bad Norton are so allergic in so many ways to rpms. Even hi end Harleys can out spin and flow most of them. Sure would like the old style cam pre oiler case bath tub.

 

[Foxy]

Gday All,
this is a very intersesting thread, keep it up!
Just wondering has anyone tried an inlet port insert to build up the port floor! Perhaps this could be made from pressed stainless and held in place via the manfold bolts and a devcon type product to hold in situ along the port floor?? :?:

Foxy

 

[swooshdave]

Gday All,
this is a very intersesting thread, keep it up!
Just wondering has anyone tried an inlet port insert to build up the port floor! Perhaps this could be made from pressed stainless and held in place via the manfold bolts and a devcon type product to hold in situ along the port floor?? :?:

Foxy

I think it was mentioned earlier in the thread.

 

[comnoz]

Gday All,
this is a very intersesting thread, keep it up!
Just wondering has anyone tried an inlet port insert to build up the port floor! Perhaps this could be made from pressed stainless and held in place via the manfold bolts and a devcon type product to hold in situ along the port floor?? :?:

Foxy

Yep , ported a lot of heads with a bolted in cast aluminum shoe in the bottom of the port. Lots of work by the time it is installed and the port is re-shaped. Don't do them anymore now that the fullauto head is available. Jim

 

[Foxy]

OK thanks Jim and Swoosh, mmm.... must be oldtimers setting in me brain!!

 

[jseng1]

Jim C

Do you know the primary wave intake tract length & the RPM range its good for? I would appreciate it.

Jim S

 

[comnoz]

Jim C

Do you know the primary wave intake tract length & the RPM range its good for? I would appreciate it.

Jim S

On the order of 16-18 inches. Depending on the cam duration and exhaust system and engine RPM you are looking to boost. It will only boost a range of around 5 to 700 rpm and hurt everything else. First harmonics was what I was using when I got a 750 up to almost 100 horse. I would have needed a 16 speed trans to use it. It also got hot quick when it was in the powerband. It acted just like a supercharged engine around 7500 RPM and a lawn mower engine with a plugged air filter at 6000. If you want to try it keep in mind you need a lot of velocity in the manifold to create much boost. Small diameter, no curves, and you need to accelerate the air slowly and then decelerate it slowly as it enters the bowl. The bowl volume and shape is critical. Everything needs to be shaped right to allow high air speed. Jim

 

[Webby03]

Just for info, I've turned up at set of intakes 13" long based on the 2nd harmonic figure to try on my TRiton.
I'll let you know in about 2 years time if it works!
In response to JimC's question, I would say play around with the formula, by changing the RPM you should be able to come with an average figure. It should work in theory, in practice I have no idea!

Webby

 

[jseng1]

Jim C

Do you know the primary wave intake tract length & the RPM range its good for? I would appreciate it.

Jim S

On the order of 16-18 inches. Depending on the cam duration and exhaust system and engine RPM you are looking to boost. It will only boost a range of around 5 to 700 rpm and hurt everything else. First harmonics was what I was using when I got a 750 up to almost 100 horse. I would have needed a 16 speed trans to use it. It also got hot quick when it was in the powerband. It acted just like a supercharged engine around 7500 RPM and a lawn mower engine with a plugged air filter at 6000. If you want to try it keep in mind you need a lot of velocity in the manifold to create much boost. Small diameter, no curves, and you need to accelerate the air slowly and then decelerate it slowly as it enters the bowl. The bowl volume and shape is critical. Everything needs to be shaped right to allow high air speed. Jim

Thanks Jim C - this is music to my ears.
Is there a primary length for 5000RPM?

 

[Webby03]

Jim C

Do you know the primary wave intake tract length & the RPM range its good for? I would appreciate it.

Jim S

On the order of 16-18 inches. Depending on the cam duration and exhaust system and engine RPM you are looking to boost. It will only boost a range of around 5 to 700 rpm and hurt everything else. First harmonics was what I was using when I got a 750 up to almost 100 horse. I would have needed a 16 speed trans to use it. It also got hot quick when it was in the powerband. It acted just like a supercharged engine around 7500 RPM and a lawn mower engine with a plugged air filter at 6000. If you want to try it keep in mind you need a lot of velocity in the manifold to create much boost. Small diameter, no curves, and you need to accelerate the air slowly and then decelerate it slowly as it enters the bowl. The bowl volume and shape is critical. Everything needs to be shaped right to allow high air speed. Jim

Thanks Jim C - this is music to my ears.
Is there a primary length for 5000RPM?

About 13" - 14" should do the job. I think it's one of those things you just have to play around with to find the ideal length.

Webby

 

[Hobot]

To extend the ways to feed your head >>>

The volumetric efficiency and resonators in an air intake system are two closely related terms for the performance of naturally aspirated internal combustion engines. This article will discuss Helmholtz resonator designs and how intake resonators work
Read more: http://www.brighthub.com/engineering/me ... z1DltKmLxl
http://www.brighthub.com/engineering/me ... 84316.aspx

Two resonate methods, so 2 calculators to play with and a teaser quote.
http://www.team-integra.net/sections/ar ... icleID=471
A suggested starting point for the length of a tube with peak torque at 6000 rpm is 13 in.
You add 1.7 in. for every 1000 rpm that you want to move the peak torque below 6000.
Or subtract 1.7 in. for every 1000 rpm you want to move the peak torque above 6000.

 

[Hobot]

Choke point calculator, plus others on home page.

http://www.wallaceracing.com/chokepoint.php

 

[comnoz]

I pulled the old race head out of storage and cleaned it up a bit for some pictures. This is the head that made 98.something horse at the crank over a very short RPM range. Notice the 1 inch of extra fins welded on trying to keep it cool. I was also circulating large amounts of oil through the head and using a huge oil cooler trying to keep it cool. See the extra passages front and rear.

I tried racing it several times. The powerband was very difficult to deal with and on open tracks where I could use it I was never able to finish a race before pre-ignition- detonation or 500 degree oil temps would stop it. It would melt the soldier holding the wires to the dyna ignition pickup if nothing else.

The head survived the shop fire [kind of] but the ceramic port coatings and Devcon is in rough shape. The head is likely beyond use. I will need to find some valves and then I will flow test it.

 

[lcrken]

Thanks, Jim. I've been curious for a long time about what that head looked like.

Sound like it might have possibilites for a Bonneville bike running on Methanol. Do you think the extra cooling from the alcohol would be enough to keep it running flat out for 3 miles or so?

Ken

 

[comnoz]

Thanks, Jim. I've been curious for a long time about what that head looked like.

Sound like it might have possibilites for a Bonneville bike running on Methanol. Do you think the extra cooling from the alcohol would be enough to keep it running flat out for 3 miles or so?

Ken

I am sure alchohol would make a big difference. I would like to try it again with engine mangement also. I think a lot of the off powerband running difficulties and some of the heat problems could be fixed with injection. What are the rules for injection at Bonnyville? Jim

 

[xbacksideslider]

Wow. That's a lot of development.

 

[lcrken]

I am sure alchohol would make a big difference. I would like to try it again with engine mangement also. I think a lot of the off powerband running difficulties and some of the heat problems could be fixed with injection. What are the rules for injection at Bonnyville? Jim

Jim,

there are no class distinctions between carbs and injectors at Bonneville. The only restrictions are in the production classes, where you have to run the production fuel system.

Will your injection system handle methanol fuel?

Ken

 

[comnoz]

Ken, Methanol fuel should be no problem with injection. Basically use the same precautions you would with a carb. The set-up would actually be easier. And with feedback it could tune it on the fly. Jim

 

[Hobot]

Methanol can be sprayed in with fuel to also get some of the octane and cooling advantage.

1. Does the D shaped exhaust help lower head heat? Is there some fudge factor in the profiling so can be done adequately w/o flow bench guidance?

2. What can be done to increase oil flow to exhaust side of head?
Seems like I've read oil is worth about 6% of Cdo engine cooling.

 

[comnoz]

My experiences with trying to get added cylinder and head cooling using oil have not been very successful. I used a second oil pump and installed jets in the exhaust rocker covers without much change. I also had a radiator the size of a large rectangular number plate mounted in the headlight position to cool the oil.

I also recall in the mid 80's when racing a GSXR which was mainly oil cooled that we could not keep it cool after we installed high compression pistons along with flatslides and a pipe. We installed larger "kit" oil coolers but after each race the engine and oil would be smoking hot. It was impossible to restart until it cooled for a bit.

I really doubt that a stock Commando engine gets much of it"s cooling by way of oil. There simply isn't much volume. Jim