Indiomike

My Feedback: (5)

Excellent comment Capt'n. I agree with you 100%. Thanks for sharing Maximiliano Galvez.

Mike

captinjohn

Indiomike, Thanks for the kind words. I would think a well desighned velocity intake stack would help allright like Mr Galves says. When I get a 20cc or smaller gas engine...I will pay him for one. Is is evident he has put a ot of thought into this part and tried it on some engines. Keep up the good work Mr Galves. Do not let a few smart ***** remarks kill you intrest in making engines run better. Best Regards to all that deserve it....Guys like Mr Galves. Capt,n

Maximiliano Galvez

CaptinJohn

really I apreciate your words
Thank you very much
Sincerely Maximiliano

DadsToysBG

My Feedback: (35)

I'm getting some and will include them in the sale of the 20. Love to try new things. Dennis

Tired Old Man

My Feedback: (1)

Is the inlet the same diameter as what is found on the DLE 20 carb or of a different size? How many poor idling engines has this solution resolved? This may be something particular to the smaller gas engines so I'm interested to hearing more about how well it works and the number of different engines it has been tried on.

wesaysoracing

looks like an annular booster found on our big cfm racing carbs, IF it works the same as our boosters do , it increases the velocity of the air improving the signal the carb fuel circuits see, in our case it improves the drivability off the corner, big cfm carbs make good power on the top end but at slow engine speeds the throttle response is less than ideal

captinjohn

That sure makes good sense too me. Thanks for you reply. Best Regards, Capt,n

Ernie Misner

Max, that is very clean work! To me it seems strange that any type of a stack would have much effect at idle ... ?

Keep us posted, thanks,

Ernie Misner

Maximiliano Galvez

Dear Ernie

In my case I design this for engine conversions. IMy first problem was in an os 120 FS, Whe I make first test engine works nices stars nice, I carburate it.

But whhen I stop it the engine dont start well again, has idle problems untill I open needle valbles, It sytarts weel and need close again Needle valbles.
STops and again same problem.

I take to much hours checking what happen. I opned walbro carburetor, change it 3 timesand dont get good solution. The best I found in this moment wasit, in the diafragm in has a little leg, tah open a vavle. I bend it for it open more (this leg always has to be calibrated, exist a tool for calibrate but i move it calibration)

the result was better but not good..


Then I decide to make an speed intake, I feell the probelm alwais was gas. I make one and test and incredible. So better, I full trotle i get 100 rpm more and no more problem in idle.. The needle valvles need to close and no more carburation needed agin.

Same pases me with a saito 120, I knew the solution, and then will all 4 strokes engines.

Wneh some guys contact me in Mexico with same probem in DLE that has problems in idle, I told them thetst the intake , tehy told me whne they tested it their porblem was solved.


Now what is the real problem in some engines??

Maximiliano Galvez

The problem is:

Gas carburetos. Like walbro and DLE (Emaz dle uses now chinese carburetor) Has an amazing working system. It has a demand regulator. It means that carburetor only takes the fuel it needs from the engine vacum.

Cabrs has a pump inside that drain fuel to a chamber. It chamber has a valve that is always closed until carburetor demand fuel. The valve is open when the diafragm senses vacum.

This diafragm ans this valve has same spring and same movement force in a 50cc carb and in a 20cc carb. Until a 20 cc carb has small ventury, the vacum of a 20 cc is small too. May be ventury is proportional for each engine, but vacum force needed is not proportional to open well the valvle in idle.

Thats what I have found. May be Im wrong but is really I have solve this problem with the intake. All my 4 strokes conversion kits includes the intake.

Lifer

My Feedback: (1)

Where do I buy one and how much?

Ernie Misner

Do they get better fuel economy with this stack?

Thanks again,

Ernie

TimBle

I'd be interested in purchasing a couple. It seesm MVVS has similar thinking with their 26cc which comes with a velocity stack.

Ernie Misner

This is more than just a velocity stack I think. Max or anyone.......? can someone please draw a (cross section) diagram of what the internal dimensions or flow for this setup looks like?

We know a regular velocity stack is nothing more than an extention. There is some "spit back" expecially with 4-strokes that have a hot cam, and a stack keeps this spit back contained rather than just making a mess around the carb area. This is how better fuel economy is obtained.

Thanks,

Ernie

captinjohn

That is a very good point. The last thing we want is fuel spray on a rear intake....it would oil up the wood-work ! Capt,n

Lifer

My Feedback: (1)

I'm still in the learning stage on gassers, but I have come to understand that rear-intake engines use a reed-type valve and that passage is only one-way, like a heart valve. So isn't spray from the carb unlikely?

Just asking.....not trying to pick a fight!

Antique

My Feedback: (4)

If the reeds don't seal well there will be some....

Maximiliano Galvez

yes in dle it has reed valvles, but in 2 strokes and four strokes small engines gas converted, it works really nice.


Instead a drawing, I cut one in half.
Regards Max

warbird72

My Feedback: (79)

What is the blue part on the back of your carb? And what do the fitting do ? Is it a way to pump fuel/gas.. Thanks Ernie.. I would love to try on of your stacks! I have a homelite 30cc converted on my Taylorcraft.. It has lots of raw gas coming out of the carb at wot! Your the man..

Maximiliano Galvez

The blue part is a plate that is the walbro support of the Saito 180 conversion kit. The fittings are for the fuel pump system. I used it for support the walbro carb and the cut intake

Regards Max

doublesixes

Please forgive my intrusion but wasn't the DLE20's idle problem CDI related? Its programming in particular. I don't own that particular engine but I read about it here and other forums.

CustomPC

As i understand it, A normal velocity stack is a cone shape and does just what the name says, increase the velocity of the air as it tries to squeeze through the narrowing venturi. The faster air mixes with the fuel better and improves the atomization.

A side benefit on some engine designs (namely those with a piston or crankshaft porting) is that when there is a back pulse which would push air/fuel mixture back out of the carb where it would normally be lost, the extra length of the velocity stack works in part to protect that back pulse from the surrounding air flow so that it can be sucked back through the carb and not wasted.

This device looks different because is narrows like a velocity stack but then it opens out. It must create some sort of negative pressure which helps with the fuel metering.

TimBle

ah very clever!

Its a venturi with a very pronounced kink line.
I see this cross section is used in the diffusor of Formula 1 cars.Does itallow for very rapid expansion of the gas back to a given pressure and more efficient andconsistentfilling of theinletto the carb? this is how the improved idle is acheived?

AA5BY

This is interesting as I've previously thought of a velocity stack as beneficial to the side mounted carb that suffered prop wash. It might be that carb throat at altitude has some issue that the velocity stack counters.

It is gracious of Max to share his discovery and provide the means of evaluation by others.

captinjohn

If you (doublesixes) think the problem is entirely CDI programing....please find the post and copy it or give us a link to the web page you read it on. Thanks Capt,n