Smaller plenum = more power?? It can!(sidewinder test too)

d_fault · Post by **d_fault** » Mon Jul 24, 2006 9:17 am

Ray, that's just one scenario... I'd probably mount the injector bungs alot closer to the head, further down the intake runner myself. The advantage there would be less turbulent air flow, which would provide a more evenly distributed a/f mixture in theory.

Jake.... funny you mention the pedal feel.... I hadn't given that a thought yet.... (strong return springs)...

If I can't locate a side draft carb for my turbo project, maybe I'll machine up a prototype and see how she does... I'd just have to do the math.

arlo · Post by **arlo** » Mon Jul 24, 2006 9:41 am

Ray, one thing to consider if you haven't yet is the force acting to hold the bullet shaped plunger toward the inlet openning at high vacuum low throttle settings. For example, with just a minimal 40mm diameter openning and around 20 inHg vacuum you have about 20 lbs force sucking the plunger toward the openning. That seems like a lot to overcome through a simple linkage, cable, foot pedal arrangement. Also, that force goes from 20 pounds to near nothing as the throttle is openned and vacuum drops off making it difficult to operate the foot pedal smoothly.

Butterflies avoid this problem since there is equal amounts of area on on both sides of the throttle shaft creating equal but opposite rotational forces that cancel each other out.

arlo · Post by **arlo** » Mon Jul 24, 2006 10:27 am

Ray, one thing to consider if you haven't yet is the force acting to hold the bullet shaped plunger toward the inlet openning at high vacuum low throttle settings. For example, with just a minimal 40mm diameter openning and around 20 inHg vacuum you have about 20 lbs force sucking the plunger toward the openning. That seems like a lot to overcome through a simple linkage, cable, foot pedal arrangement. Also, that force goes from 20 pounds to near nothing as the throttle is openned and vacuum drops off making it difficult to operate the foot pedal smoothly.

Butterflies avoid this problem since there is equal amounts of area on on both sides of the throttle shaft creating equal but opposite rotational forces that cancel each other out.

raygreenwood · Post by **raygreenwood** » Mon Jul 24, 2006 12:06 pm

There will actually be little or no suction....and certainly no more than a throttle plate. The equal force issues working with a throttle plate...is only true....out to about 1/4 throttle opening. After that point......you get a LARGE amount of force operating on the outward edge of the plate. This is due to the high angle of attack of the air to the edge of the plate. There is just as much suction if not more on areas of the plate. This is also why many late model throttle plates use capstans (like in the watercooled VW's)....to generate leverage. This is also why all throttle plate systems use a lever instead of a direct wrap around the shaft.
I say large amount of force...but it is not really more than a few pounds. That is easily overcome with two different sources of leverage that are already in-line (a) the length ad pivot point of teh gas pedal. If you have ever pushed on carburetted gas pedal with your hand...you find a surprising amount of force is needed. It is easy with your foot because it pivots from one end and is a pulley system. (b) The lever on the throttle shaft....is leverage increase/multiplication.

What you are also not seeing...because I have not placed drawings out there....is that there is little if any suction on the "bullet/plunger" system. This s because the TB bore....is straight. Many may be assuming that I am suggesting a tapered plunger into a tapered bore. That is not the case. That would be a restriction.
The "bullet/plunger" is tapered. As it moves outward....while the throttle is being opened......it is compressing against its return spring......and the air is accelerating down a tapered cross section. In effect...the "bullet" is shaped like a tear-drop with the taper toward the inside of the plenum. This actually has the effect....of creating outward force on teh bullet against the return spring. If it is shaped correctly...it will have little or no force on the bullet. This is also why attenas and radio-sonds on older aircraft appeared as teardrop shaped appendages on teh outside of teh aircraft. That shape creates no lift via frontal contact with the air....but also creates little or no suction/turbulence behind it. It does have.....a relatively high rag coeffiecnt due to its shape.....but the small size/area....as in this case....is negligable. Only if it was a true "boat-tailed" shaped bullet...would you have suction operating against the bullet.....and only from the rear quandrant. Ray

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Mon Jul 24, 2006 12:13 pm

Ray, I'm up to doing some dyno work on this for sure!

914fan · Post by **914fan** » Mon Jul 24, 2006 12:34 pm

I like this concept. It is almose diesel in its lack of a throtle. You could probably use a diesel intake, atleast the throtle area. I have been told that a lack of throtle is one of the efficiency perks of diesels. Something about the area where you would normally see a throtle is akin to a venturi. For that matter you could just use a large ventiri in place of the throtle body.

raygreenwood · Post by **raygreenwood** » Mon Jul 24, 2006 3:48 pm

Jake....my drawings are ink line drawings. I will clean them up, add true diemensions and scan them into my computer by Wednesday. I think the first and easiest one would fit a 1.8/2.0 but TB. I will drop in the part # of the throttle body as well. I may even have a couple of bare spares I can send to you.

The drawings are of the mount and pulley system for the TB. Almost any TB with a bit f a bell on the air cleaner side will do.. It is a two piece brace that should be able to be simply cut from aluminum plate by water-jet. I have a few proposed cross sections and all of the plate cross section versus "cone" cross section lift studies. Those are what generated the proposed cross section of the bullet.

I have not had a "bullet" turned on a lathe yet. For about $20 of material....I can have it turned from teflon bar. Between its heat resistance, and its ability to not wear the TB bore where it seats against it....it may be a good material. Certainly easy to turn. For that matter...since the TB rarely gets over 165f or so....high temp UHMW polyethylene would be fine....and about half teh price.

I have at my disposal a nice digital anemometer. Reads FPS, CFM, Liters per minute air-speed...all of it. One of the easiest things I have been thinking of...is to make a bullet....then put it on a rod...and insert it in a plexiglass tube about 4" in diameter. Then light the smoke charge and put a high CFM blower on the other end....just to see how the shape works on its plenum end....with creation of turbulence. This will tell you nothing of how that bullet will react in the TB bore yet....but its a good simple place to start.
I have a local jobber source for smoke cartridges. They are made for HVAC testng . They produce about 8 minutes of high density white, non-toxic smoke at about $3 each. Ray

farmer · Post by **farmer** » Tue Jul 25, 2006 4:19 am

Dang ! My head`s all fuzzy now. But good thread. certainly leaves food for thought.

I´m kinda surprised that the sidewinder is "that" bad, compared to a regular 4-1. I was looking forward to not having to have the header sticking out the back, and keep good power.
T

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Tue Jul 25, 2006 4:45 am

As i stated, it a culmination of the 40" primaries, colector and the muffler.. Just getting rid of the standard muffler did a lot of good, but it still doesn't compare with the regular A-1 with 32" primaries and the same collector.

Until those 40" primaries go away I don't think we'll ever be able to manipulate it into a very efficient arrrangement, but I could be wrong! Unfortunately the primaries being that length are a must for the design of the header..

tallqball · Post by **tallqball** » Tue Jul 25, 2006 9:41 am

What about making the 4 primaries shorter, with longer "2s" before the collector makes it one?

Another thought would be tapered manifolds that grow in size as you add the second cylinder. Then you can run a single pipe from each bank to the collector.

Q

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Tue Jul 25, 2006 9:53 am

What about making the 4 primaries shorter, with longer "2s" before the collector makes it one?

No space..
Plus its still runner length and even at 4-2-1 40" is too long...

huw'sspeedster · Post by **huw'sspeedster** » Wed Jul 26, 2006 6:17 am

What is the realistic time frame for a good sidewinder it seems to be getting further and further away,I know this is well down the line in your list of priorities,but just wondering weather biteing the cost bullet and going for a tangerine racing exhaust is going to work out benificial in the grand scheme?I know i havn't got the kit yet or even sorted the cylinders but the tangerines arn't off the shelf items and i dont want to have the engine waiting an exhaust for too long!Should be getting news on cylinders today so fingers crossed!
Thanks
Huw

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Wed Jul 26, 2006 7:05 am

What is the realistic time frame for a good sidewinder it seems to be getting further and further away

With my given development schedule, I'd say it would be at least 6 months before we'll have anything developed for a sidewinder.

Due to all the intense work involved don't be suprised if I require a minimum of 10 systems to be sold before I do the development, with the cost of fuel these days we could incur several hundred bucks in expense just to do the dyno work, not counting the time... Time is our most precious commodity.

huw'sspeedster · Post by **huw'sspeedster** » Wed Jul 26, 2006 7:51 am

I understand that and that good parts developement costs on the final product so the sidewinder price is probably heading towards or well over $1k so the tangerine system is looking like a viable alternative!

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Wed Jul 26, 2006 8:13 am

huw'sspeedster wrote:I understand that and that good parts developement costs on the final product so the sidewinder price is probably heading towards or well over $1k so the tangerine system is looking like a viable alternative!

And we know it works!