Single Carb. Conversion, VW Plenum & Modding, the OEM Manifolds

[westgl]

This Is why we do NOT want to Hard Weld everything together.

If the engine Does NOT respond the way you had hoped for.

Or if you want to change/ slap a different carb. on top of that VW plenum, tuning adjustment can be made.

This manifold is like Legos, I can take one part out, Tune it differently, to the way i want it, very easily.

If you had a slight hesitation, and it were all hard wired together,

It would be impossible to tune.

You would have to either live with the problem or build another one.

 

[westgl]

If there is a slight Hesitation.

Reduce the tubing size ID, to speed up the air/fuel charge speed.

This will also Increase Engine Torque.

You want a Torque Monster, and dont care about going much over 85-90 MPH, reduce the tubing runner size.

Now you have GL1500/GL1800 6-cylidner felt torque.

 

[westgl]

All engines will be slightly different.

Based on compression ratio, and how much/fast the engine can pull that mixture in.

Modded engine is different too.

Low compression, maybe a little different than a engine that is on the high side, with all matching comp. ratios between cyl.'s.

So adjust-ability is a good thing

 

[Jungo]

I read this info on a VW mod webpage. Hope can help. https://www.christopherwking.com/projects/aircooled-vw-fuel-injection/

====================================================
A few rules of thumb when constructing a plenum and intake runner system:

Plenum = or 1.5-2 times bigger than a single cylinder volume OR 2.25-2.5 times a single runner volume
Single runner volume= single cylinder volume. If this cannot be accomplished, it can be compensated for by adding more cc’s to the plenum
Runner diameter= intake valve diameter minus the diameter of the valve stem (you want good flow from runner to port)
Throttle Body Diameter= 1.25 to 1.5 times the runner diameter
====================================================

Goldwing GL1000, GL1100 Intake Valve Specs:
Intake Valve diameter= 1.496"
Intake Valve stem = .2595"

1.496-.2595 = 1.2365"

My pipes are 1 3/16" ID (1.1875" ID) so I'm planning keep the pipes size and reduce a little the the end to increase the flow. I'll post results as soon as I do the mod to the pipes, unless you guys see I'm doing something wrong.

 

[westgl]

Ride Report for Rev.3

Rev.3 is the Best yet.

It has most of the torque that Rev.1 had, but shifted it up the rpm range a slight bit.

Rev.3 does not pull as hard down low as rev.1 did, but mid and top are better than rev.1

Meaning that, I cannot, pull from 1800-2000 rpm in 4th gear, like i could with rev.#1

But if down shifted to where rpm is in the 2500 rpm range, it pulls well from there up.

But it has No hesitation, and it has more torque than the OEM 4 carb rack had.

Mid and upper is better than rev.1

From a dead stop, it rode really good.

From a roll on it was really good.

 

[dan filipi]

How's the idle with revision 3.
Still lopey or steady?

 

[joedrum]

someone explane what jungo said and the article I was having trouble figuring out the bah bah of the link

 

[westgl]

Twisting the Oem manifolds gets you a straight shot in.

The stock type III or IV intake tubes may work really well, once the 2ea oem Manifolds are twisted.

The Type IV tubes fit right inside the plenum outlets.

You could probably use the stock type IV seals and clamps

 

[westgl]

The Idle of Rev.3 has settled down.

While it has some slight lope to it it is not like it was.

I had to idle it down, it gained 200 rpm at idle.

I wanted to see how much power form a dead it had on gravel.

I Burned out about two-three feet, then started getting side ways, I let off as I did not feel like going down with the ship.

 

[westgl]

Temp during test ride for Rev.3 was 51 degrees,

It is back to Instant restart, revs very quickly.

I want to test ride it some more i will hook back up my heater/support bracket to the bottom of plenum.

I made a cable hold bracket, hung off of the right upper motor/Frame mount bolt, it is much simplified.

Tomorrow is supposed to be a warmer day.

I want to ride it when it is about 70 degrees out.

 

[canuckxxxx]

West,

To be clear, REV 3 is 1 1/4" runners with some kind of choke where the runners enter the plenum...is that right?

Not clear as to why the chokes are needed. Could you post a picture of a choke?

Brian

 

[joedrum]

to speed the air for carb to atomize gas right

 

[westgl]

Yes I put in 1"ID chokes, that opened up to 1-1/4" ID tubing.

The Plenum has been opened up to 1.400" ID in the Outlet, going further up into the outlet, before where they have been opened up, you can see they measure approx 1.0" - 1-1/16".

So my choke reduces the ID size of that transition, from 1.400"ID down to 1.0" id, to speed up the air/fuel charge speed.

When I did rev.2 with No chokes and 1-3/8"ID tubing, the charge speed, seemed to be the cause of the bike falling on it's face, from a dead stop and having some hesitation.

When I did rev.2.2 just adding the chokes it was much better, but still had some hesitation.

Rev.1 did not have any hesitation, the ID on the hose was reduced down to 1.100" ID, but it did not have any chokes, Rev.1 mid range to top end was not as good as Rev.3.

But i noticed some hose collapsing, which may have reduced down My ID even further, and speed up of the charge may have taken place.

 

[westgl]

Here is a picture of the choke, the choke has a tapered entrance, like a funnel.

Choke lower left

P1020167

• westgl
• Oct 3, 2013

Choke is lower left, new Rev.#3 runner is upper left, Rev.#2 runner is upper right, lower right...

Choke telescopes inside of the 1-5/8" tube, as a reduction, but charge speed seemed to slow down too much using the 1-5/8" ID too much volume and not enough speed.

Shorter choke used .75" L 1.0"id choke into a 1-1/4"ID runner.

This has been the best so far, I almost did not make one of the turns, it is fast!

I went over the line in front of a on coming car, could have been bad.

It picks up speed pretty quick

 

[joedrum]

sheesh ...im floored ... so now it appears that the only two manifold setups that worked good so far ....is hooch and its original setup .. of 1 1/4 hose and 1" chokes that I did from the get go with the 32-34--24-25 carb and it also ran the ...32-32--22-22 carb .......I actually tried the 1 1/4 runners with no chokes and it didnt run at all for me......

I never said a lot here because I thought westgl was having great success with it ...this was just after the wreck I had and I just figure I was to hurt to get it right got really sore and quit messing with it and put it back with the chokes in and tried smaller carb ...when I did that it ran just fine ...and is how it sits now .....

so with the success of westgl best setup and mine its obvious this is a set up that works good ....getting these manifolds set up right has more to do with this setup ...than things like s curves and bs people are putting so much weight in ....id say strait runners is and upgrade but it don't have the effect like choke and runner do ...

so this set up as done on hooch from the beginning has proven to be good set without question as hooch and westgl bike has proven to like this setup ...hooch 1200 mod bike and westgl 1100 stock set up this is all huge info to me for the forum ...just want to make this point clear

other setups are being tried and that great as long as we don't forget ..this set up is successful we are not looking at finding something that works were improving on or trying to

a successful set up is already been found .... :yahoo: :yahoo: im just thrilled :mrgreen: :clapping:

 

[westgl]

I agree with you Joe,

The only thing from here, is to do what Dan is trying, reducing the tube size down even further, to get the power off of the top end, and down into the lower torqier side.

I think that too is a good idea.

Taking some of that top end power, off the top, and putting it into the lower to mid range power band, is going to make a really fun riding bike.

 

[westgl]

I am going to get into the 70' degree weather the next three days.

It will be a good time for some test riding, of Rev.3.

I cleaned up the look of Rev.3 by just sanding the runners with 150 grit, to give it a brushed look.

It looks better than just raw alum. tube

 

[canuckxxxx]

westgl » Thu Oct 03, 2013 5:52 pm[/url]":1a52g8j1]
Yes I put in 1"ID chokes, that opened up to 1-1/4" ID tubing.

The Plenum has been opened up to 1.400" ID in the Outlet, going further up into the outlet, before where they have been opened up, you can see they measure approx 1.0" - 1-1/16".

So my choke reduces the ID size of that transition, from 1.400"ID down to 1.0" id, to speed up the air/fuel charge speed.

When I did rev.2 with No chokes and 1-3/8"ID tubing, the charge speed, seemed to be the cause of the bike falling on it's face, from a dead stop and having some hesitation.

When I did rev.2.2 just adding the chokes it was much better, but still had some hesitation.

Rev.1 did not have any hesitation, the ID on the hose was reduced down to 1.100" ID, but it did not have any chokes, Rev.1 mid range to top end was not as good as Rev.3.

But i noticed some hose collapsing, which may have reduced down My ID even further, and speed up of the charge may have taken place.

I can see how the choke would speed up the air and keep the fuel atomized.

Are these chokes something you make yourself on a lath? or can you buy them? Could the same affect be had by putting an orifice plate at the exit of the plenum, that is a 1.4" OD washer with various sizes of hole sandwiched between the manifold runner and the end of the plenum spigot. That would be much simpler.

Right now REV 3 is unheated right? When I ordered my carb. from Tom Langdon he really stressed the need for lots of heat on the plenum and runners in order to keep the fuel atomized. Perhaps if you had lots of heat applied you wouldn't need the chokes.

Maybe, with no heat and no chokes, it is like an engine that is not warmed up, that is, hesitation and flat spots.

Brian

 

[joedrum]

on perfect day with no need for heat it don't work ....my chokes are plastic pipe and funneled with a tapered ream ... it don't get any easier to me ...they work great and are perfectly shaped .... :builder: :mrgreen:

 

[ekvh]

At this point, it seems that the only mods that have worked without some sort of negatives are the ones using the vw type iv intake. Perhaps there is something to the collector inside the plenum which funnels the charge and keeps it moving down the tubes? I'm sure there is something that can be done with these other mods using the stock plenum, but at $60 versus all the labor involved in the other mods using the stock plenum, it looks to be the best and safest bet. I enjoy reading all the experiments.