supertib

So basically what your trying to say is your unsuccessful with nitro engines and your experience is nothing more then a couple RTR's .... LOL only on RC universe ! and everyone wonders why all the old timers left for RC Tech......

FYI...based off what you were saying I was able to guess you had very little hands on nitro experience....so take that for whats its worth..

phmaximus

Omg, u just don't seem to get it do u, how can I simplify it just for u to understand,
Honestly is that how u read my post?
how come u can't understand that the boost pressure if higher than the exhaust pressure? It's like u have no concept of turbo charged engines?

So if the boost pressure is higher than the exhaust pressure..... That means..... The fuel tank is at a lower pressure than the boost pressure, no one said it was lower than atmospheric pressure

Oh wow, I wonder if he gets it now,

phmaximus

Yes I know that I was dumbing it down and using that for referance for u to understand, but somehow u don't.

Ummm yes turbo drawthrough carbys do have pressureised fuel bowls under boost, how els is the Venturi going to work. Come on its not rocket science. Even the google warriors know that

phmaximus

How can someone that is a engine builder completely not understand engine mechanics, how can u not understand the highlighted part? Is English ur first language? I seriously can't dumb it down any more.

The Hedgehog

Please keep the dumbing down to a minimum. Reading your posts make my head hurt [:@]

phmaximus

Ok smarty pants, is this dumb enough.

If the fuel pressure is lower than the boost pressure what forces are going to get the fuel out of the carby....
Are u relying on magic lol,


Oh wait..... Now he gets it, ding ding ding.... No go back and re read my post

phmaximus

Rather that trying to insult me, why don't u try explaining yourself.

U explain why u think that I said that the fuel tank has a lower pressure than the atmosphere?

I never said that did I, that was ur mistake interpreting my post wasn't it?

I said its lower than boost pressure dident I? I've said it nearly 10 times now even in the hpi gasser thread.

How can u get it so wrong? What is wrong with u?

phmaximus

Here I'll dumb it down again,

Let's say we have 2 pressure vessels

The first is pressurized at 17psi

The second one is pressureised at 15psi

If we connect them together, what happens? I know do u



Now let's say the first one is a carby 17psi

And the second one is a fuel tank 15psi

And the connecting line is the Venturi and fuel hose

How is fuel going to flow from a lower pressure zone 15psi to a higher pressure zone 17psi

it can't, it's impossible, fuel will not flow into a higher pressure zone, Unless the fuel pressure is greater than the zones pressure.

Physics 101

phmaximus

What do u mean by unsuccessful?
What does that mean in your context?
Is that u been narrow minded and thinking I had problems with them. or is it just another pathetic way of trying to insult me?
More like I ditched nitro because I found brushless motors to be more powerfull, a cheap $80 combo puts out more power than a .15 nitro motor, and it cost only $0.01c to charge my battery.

Yes 3 rtr's.... What does it matter if it's a rtr? Do u think the engines are different on kit cars....lmao what possible differences in experance would I have if they were kits??? U do know the engines in the kits are per assembled right?

If u like old timers so much go to a gay bar. It might clean that blockage in ur exhaust

Nitrovein

So that was "physics 101"?! Here´s "logic 101";
Has anyone claimed yet that they know how high the pressure is from the pipe?
Do you know?
Does "supertib" know?
How much does the pressure increase from the pipe as the engine starts to push more gases through?
Do you know?
Does "supertib" know?

You need to read between the lines and grasp the fact that not all facts has been presented yet!

757jonp

My Feedback: (48)

Maybe iI've led a sheltered life, but I haven't seen many glow engines with a full size automotive type carb with a float bowl.... someone needs to start thinking varible venturi, helixes. and spray bars

Where were we anyway. I had to step out and get some popcorn.

proanti1

My Feedback: (2)

TL;DR:

supertib acts a fool, and can't spell.

phmaximus instigates supertib into an incoherent rage.

cumminspower5.9

My Feedback: (4)

Is it me, or has this gotten out of control, and yet nobody is making any sense on what we are trying to accomplish? Here's an idea... all the 2-stroke nitro engine pros need to put their theory to the test instead of arguing and actually see who is right on how it is going to work. You can bicker and argue all you want, but you aren't getting anywhere. There are a lot of variables that are going to come into play for this to be done efficiently, so get started. Just my two cents.

phmaximus

Is that what u got from my post? What's going on????!
Why can anyone understand it?

I never said that glow engines have a float/fuel bowl? What???

I was using it as a example to show people that the pressure needs to be equal on both sides of the Venturi for it to work(pickup and outlet)

The pickup for a real car is the fuel bowl and for a Rc car it's the fuel tank, regardless what u call them it's still a fluid vessel that needs to have equal pressure at each end of the Venturi so it can be a Venturi otherwise it's just a pipe, having a lower pressure at the pickup compared to the outlet won't allow for the Venturi to work.
For the simple folks, so stop taking my posts out of context.
Get out a dictionary and look up the meaning of lower. When I say "lower pressure at the pickup" it does not mean its lower than atmospheric pressure, it means it's lower than the outlet pressure

Why are some people struggling to understand this?

It's very easy to understand if u open ur mind. And read the posts, not just skim read or jump in 1/2 way during a debat

phmaximus

Lol I know, to long *sigh

If u do get time read the post with the pic of the simple carby please do.

See if u can explain to supertib and sparky how a Venturi does not work if there is higher than atmospheric pressure at the outlet and only atmospheric pressure at the inlet, please I beg of u...

No matter how I try to explain it, they just don't understand it

supertib

How are you assigning a value of 15 PSI to the fuel tank ? where do you get this number from ? You do realize that the fuel tank sits at a higher pressure then atmosphere right ?

FYI the fuel tank is pressurized by the exhaust system.... it sits several Psi above atmospheric at idle and increases more and more as the engines RPM or load increases..........

On my silenced breakin stand If I remove the pressure line off the fuel tank I can hear the pulses of air thru the hose.... pfffht.pffffht,pffffht,pffffh,pffffh with each pulse of the engine...and since these engines idle at 9000 RPM we have a pulse rate of 150 pulses per second feeding the fuel tank...similar to an aquarium pump .. On the breakin stand if I pull the pressure line the engine instantly runs lean.............The tanks operating pressure is very reactive to what the engine is doing...as the fuel tanks internal pressure will match what the internal fuel pressure of the tuned pipe is.....On some of the cars with my modified engines we have to strap the lids of the fuel tanks down to keep the pressure from blowing the lid open.....The stock spring on the tank lid is not enough and we have to wrap auxiliary bands around the tank and lid.... So trust me we don't have any issues pressuring the fuel tank.....We generally already make more pressure then some of the tanks can handle.. .... No matter what the pressure in the exhaust pipe will never be lower then the atmospheric pressure...

So now I am struggling to see your point...The fuel tanks will always sit at a higher PSi then atmospheric....even when I up the inlet pressure the fuel tank will always be above atmospheric, fuel flows even without the venturi effect...As the fuel tanks is always be at a higher pressure then the spray bar...

So think about this like we have a good sized aquarium pump hooked up the fuel tank... And the aquariums pump has a VFD type drive system that regulates the pumps output frequency to match the engines RPM.....Every single time that piston fires the engine will get a shot of fuel replace the one that was just burnt.... As the RPM and load go up, the pump get turns up......... In the end these engines are a basically a 2 HP air pump....And a pile more actually comes out the exhaust then goes down the carb.......

Tonystark

Its so simple guys come on. heres the bottom line. If your going to subject any engine to an atmospheric pressure higher, than normal, then your fuel system must be subjected to the same change (carb float vents pressurized) or compensate (fuel injector nozzle/pulse increase).
These little engines are different, as the way the fuel is fed to the engine is by the pressure in the exhaust.  bottom line more air= MORE FUEL, no ifs ands or buts.

sparky 25

That's what we're all trying to get through to phmaximus

These engines run a pressurised fuel system,

the more boost on the exhaust end the more pressure goes into the fuel tank,

thus feeding more fuel the carb.

757jonp

My Feedback: (48)

You keep talking "lower pressure" when you should be talking about vacuum... The purpose of the venturi in a carb is to produce a vacuum to draw fuel from the float bowl (just a storage vessel for the fuel). It's like sucking soda through a straw...

Equal pressure either side of the venturi.... so what.

phmaximus

Yeah mate I know that, I've replaced a tank o ring or 2 before

Yep I know, still not what im talking about tho

I agree with that and I'm not debating that at all

That's what I'm talking about, u are right and wrong
Normally that is 100% right, when the so called turbo spools up and created positive pressure it's all different
Under full boost the tank pressure is Lower than the spray bar. Under full boost there it would lean out very fast and wouldent flow any fuel at all.... Please for the love of god I hope u understand my point.

Ahhh yes but that pump in not going to work that well if the boost pressure has more pressure than it does


Like I said before I'm talking about the fuel delivery under full boost, not off bost, after all this is a turbo thread.

So I ask, for nearly the 5th time, how will there be fuel flow under full boost if the boost pressure is higher than the fuel pressure
Or u could say.... How will there be fuel flow if the fuel pressure is lower than the boost pressure
Both questions are asking the exact same thing, and yes I know they are both higher than atmospheric pressure

Noticed I never said low pressure, I said lower. Yes a low pressure zone is under atmospheric pressure, but a lower pressure is not allways, it just lower than what it's been compared to, it doesn't mean lower than air pressure?

Rember guys, low air pressure is completely different to lower air pressure

phmaximus

Umm no, that's not what I'm talking about

phmaximus

That's what I'm trying to get through to sparky.

He even agreed with ur post but he doesent understand

"If your going to subject any engine to an atmospheric pressure higher, than normal, then your fuel system must be subjected to the same change (carb float vents pressurized) or compensate (fuel injector nozzle/pulse increase)"

They seem to think that u don't have to do that. Because they think the exhaust pressure is enough. even tho boost pressure would be higher than the fuel system pressure

So with there setup it would NOT be subjecting the same condition on each side of the fuel system

My idea of a equalizing hose would have the fuel system subjected to the same change under boost where with out it there would be a pressure difference under boost that would reverse the fuel direction

supertib

it is impossible for the fuel pressure to be lower then the intake pressure..

the fuel tank will always be at a higher pressure then the engines intake.,...its the simple mechanics behind these engines... as no matter how much air we cram down the carb the exhaust will always have substantially more pressure then the intake side of the engine..... ........

you do realize that "Boost" is only air right ? and your must realize that if we increase the intake air volume by 30% we will also increase the exhaust volume by 30% as well................so no matter how much air we suck into the engine the exhaust pressure will always be proportionately as strong ... We could triple the volume of air going into that carb and the fuel system will always keep working just the same...........

t-max97

My Feedback: (9)

Exactly, ph do you think there will be more air going in than coming out??? If you increase the fuel/air you will proportionally increase exhaust therefore increasing tank pressure, not saying a turbo will work well on these idk but I dont think that will be a problem.

franko1964frank

HPI RS4 MT SUPER NITRO HPI 18SS ENGINE W/5.5-5.7MM 1634 2 NEEDLE ROTARY CARB EBAAAY ITEM NUM 271127370326 FASTEST MOTER IV EVER SEEN!!!!!! FRANKO.