Building a 10,000 rpm NA engine. - Page 34

bazza · #**496** 12-03-2012, 12:38 AM

Quote:

Originally Posted by Dessertrunner

I understand all the theory but you miss the point that I am trying to make and that is the need to get better air mixing of fuel when it goes into the cyclinder.
It is a known fact that if you got perfect airfuel mixing you will get maxium burn and therefore maxium power is all other factors are equal.

Quote:

Originally Posted by Dessertrunner

Bazza I don't agree at all,

You are totally missing my point but thats the way life is.

Tony

Tony I understand completely what you're trying to achieve but I highly doubt it will work on our old engines. This thread is here to discuss such anyway so post away if you wish.

You also said "the need to get better air mixing of fuel when it goes into the cylinder" which means you're assuming our engines mix air poorly. You're also assuming that improving the mix will make more power.

oab_au · #**497** 12-05-2012, 04:10 PM

Quote:

Originally Posted by Dessertrunner

I understand all the theory but you miss the point that I am trying to make and that is the need to get better air mixing of fuel when it goes into the cyclinder.
It is a known fact that if you got perfect airfuel mixing you will get maxium burn and therefore maxium power is all other factors are equal.

The idea that you are getting sequencial injection when the duty get close to 100% is crazy.

What we know as facts are:-
Sequencial injection is better then group or batch firing.
The better the fuel air mix the better the burn.
Air velocities in the intake manifold change based on when the valve is open.

The way I see it we want to take those knowns and build on them.

I would have liked to have been in, on the start of this conversation, seems like it been on for a while.

I agree with you on the need for the injectors to produce a good atomisation of the fuel right through there range. Two injectors are used so the small one can spray a fine mist at idle and low rpms, while the larger one can handle the larger mix.
Larger injectors do not spray well at low openings, they tend to dribble, and fuel droplets don't burn, only a vapour will combust completely.

I don't understand what you all mean by

Quote:

As for the 40% duty, that means the injector is open for about 288 degrees - which means if you want the valve open the entire time - you need inlet cams with that duration. Standard SVX cam is about 236 degrees, means you'll need to run max of 33% duty if you want the injector open only when the inlet cam has the valve open. However it doesn't work like that in reality... they usually finish injection 300-400 degrees BTDC, about 300 degrees before the cam is even thinking about opening.

The way the SVX is injected is always sequential, and all the fuel is injected before the inlet valve is opened. The max injection time is about 16ms, this time will take about 58* of rotation at, 6000 rpm, so the injection starts at about 65* before TDC, and is completed before the valve opens.

The way injection has gone over the years is purely for emissions, we don't get any more power now, than we did before, with continuous injection. It is all about Hydrocarbons and fuel economy.
The need to reduce the emissions meant that we can not have a wet manifold like we did with the older units, continuous or batch injection. So we have sequential port injection, but now we have to eliminate the port getting wet with fuel, so we go to direct injection.
As long as the fuel is at the right air/fuel ratio and it is atomised properly there is nothing that we can do to improve the combustion pressure, and this is the main objective.

Harvey.

Dessertrunner · #**498** 12-06-2012, 12:40 AM

Quote:

I agree with you on the need for the injectors to produce a good atomisation of the fuel right through there range. Two injectors are used so the small one can spray a fine mist at idle and low rpms, while the larger one can handle the larger mix.
Larger injectors do not spray well at low openings, they tend to dribble, and fuel droplets don't burn, only a vapour will combust completely.

On this point we are on the same page Harvey, everytime guys use 750cc injectors their cars don't idle well at all. The point I am making is don't bother trying to get a better mixing in the cyclinder head by fancey design when you are sending the fuel into the cyclinder in liquid form. You need it to still be a gase or mist.

Next point you make I am not so clear on, when you do the maths on a injector calculator our injectors are running around 80% duty which is the number that was given before when I asked the question. I understand that 100% duty means the injector runs full time. Am I wrong on my understanding of what 100% duty means.

Okay so this is were my heads at,
On a NA engine the big ticket show stoppers are:-
- The amount of air and fuel you get in the cyclinder per fill,
- The amount of energy given back from that burn,
- AND (hold your breath Harvey) the number of times you can do it in a minute with out effecting the two about.

Harvey you may agree that there is a understanding in the welding game a fuel tank empty goes bang quicker then a full one. On a cold day you can throw a match into a tin of petrol and it will go out, On a hot day the thing will blow up from 20 ft away.

In other words the right ratio of air to fuel DOES MATTER to little and you get a bad burn to much and you get a bad burn.

By the way team I have been running my car at engine temp of 75C and have expected the fuel usage to be bad but it seems that the fuel consumption is better. On that one I will keep you post.
Tony

oab_au · #**499** 12-06-2012, 01:43 AM

Quote:

Originally Posted by Dessertrunner

On this point we are on the same page Harvey, everytime guys use 750cc injectors their cars don't idle well at all. The point I am making is don't bother trying to get a better mixing in the cyclinder head by fancey design when you are sending the fuel into the cyclinder in liquid form. You need it to still be a gase or mist.

Next point you make I am not so clear on, when you do the maths on a injector calculator our injectors are running around 80% duty which is the number that was given before when I asked the question. I understand that 100% duty means the injector runs full time. Am I wrong on my understanding of what 100% duty means.

Yes I was not sure what was meant, but
I would think it means that the injector is running at <16ms, arnd has reached its maximun flow rate.

Quote:

Okay so this is were my heads at,
On a NA engine the big ticket show stoppers are:-
- The amount of air and fuel you get in the cyclinder per fill,
- The amount of energy given back from that burn,
- AND (hold your breath Harvey) the number of times you can do it in a minute with out effecting the two about.

Yes I agree with that, the key bit is
"The amount of air and fuel you get in the cyclinder per fill",
This becomes harder to achive as the time becomes less, so we can get the RPM, to get the HP, but not at the cost of a lack of go.

Quote:

Harvey you may agree that there is a understanding in the welding game a fuel tank empty goes bang quicker then a full one. On a cold day you can throw a match into a tin of petrol and it will go out, On a hot day the thing will blow up from 20 ft away.

In other words the right ratio of air to fuel DOES MATTER to little and you get a bad burn to much and you get a bad burn.

By the way team I have been running my car at engine temp of 75C and have expected the fuel usage to be bad but it seems that the fuel consumption is better. On that one I will keep you post.
Tony

Cheers Harvey.

SilverSpear · #**500** 12-09-2012, 12:44 PM

Quote:

Originally Posted by Dessertrunner

Okay Bazza and I have been having a debate about the dry sump. I personally think that we should use a 2 or 3 stage pump and forget about pumping oil back from the heads. One of the stages needs to be pressure.

In the mid engine thread I will post a image of the engine block sitting in the subframe with the new engine mounts etc and you can see how low it is, not sure were I will discuss the simpler dry sump set up but will explain it in the near future.

Tony

Tony, Bazza, what is the status on the dry sump system?

bazza · #**501** 12-10-2012, 03:36 PM

.................

icingdeath88 · #**502** 12-10-2012, 04:17 PM

Bazza what RPM do you have the idle set at?

bazza · #**503** 12-10-2012, 04:27 PM

.........

On 2nd thought, i've removed my posts. I'm not going to argue engine basics.

SVXRide · #**504** 12-10-2012, 09:37 PM

Bazza,

Enjoying your DYI page! What's the offset on your RPF1 rims?

Bill (thread jack over...)

SilverSpear · #**505** 12-10-2012, 10:06 PM

Quote:

Originally Posted by SVXRide

Bazza,

Enjoying your DYI page! What's the offset on your RPF1 rims?

Bill (thread jack over...)

From the look of it, I would say he is running 265 or 275 on 35, 18inch rims.

Dessertrunner · #**506** 12-11-2012, 02:10 AM

A little update, I have been flat out at work but on Saturday I managed to build some (10 of) SVX engine racks as currently the spare engines are scattered around the dyno. So next weekend I plan to stack the engines and drag the dyno out and start nutting out the changes to the dyno.

As regards dry sump Bazza didn't get time to install it on his current engine so it may have to go on one of mine.

Injectors and were I am coming from on the issue.
Everyone is aware that if a injector fails to mist the fuel then the engine will be hard to start won't run correctly,
From my reading it seems that when the valve is closed and the duty cycle is hi the fuel from the inject gets sprayed against the side of the intake manifold and the back of the valve. when this happens some of that fuel turns liquid and forms droplets. When the valve opens this is sucked into the chamber in liquid form. It maybe that with in a very short time it turns to gas but it still was a liquid. If we remember that a poor misting injector causes a engine to run badly then it stands to reason that the more liquid forming before the valve opens the more the issue of lost power.

In short the higher the duty cycle the higher the chance of the fuel turning to liquid before its sucked into the chamber.

Tony

SVXRide · #**507** 12-11-2012, 10:15 AM

Dyno, dyno, we want the dyno!!

What are the parameters you'll be measuring and at how many locations (where relevant)?

Thanks again, Tony, for all your hard work!! The "Aussie SVX Crew" is something else!

Bill (starting to consider more and more the thought of spending some time in Australia)

Quote:

Originally Posted by Dessertrunner

A little update, I have been flat out at work but on Saturday I managed to build some (10 of) SVX engine racks as currently the spare engines are scattered around the dyno. So next weekend I plan to stack the engines and drag the dyno out and start nutting out the changes to the dyno.

As regards dry sump Bazza didn't get time to install it on his current engine so it may have to go on one of mine.

Injectors and were I am coming from on the issue.
Everyone is aware that if a injector fails to mist the fuel then the engine will be hard to start won't run correctly,
From my reading it seems that when the valve is closed and the duty cycle is hi the fuel from the inject gets sprayed against the side of the intake manifold and the back of the valve. when this happens some of that fuel turns liquid and forms droplets. When the valve opens this is sucked into the chamber in liquid form. It maybe that with in a very short time it turns to gas but it still was a liquid. If we remember that a poor misting injector causes a engine to run badly then it stands to reason that the more liquid forming before the valve opens the more the issue of lost power.

In short the higher the duty cycle the higher the chance of the fuel turning to liquid before its sucked into the chamber.

Tony

Dessertrunner · #**508** 12-11-2012, 06:15 PM

I just had time to watch the video that Bazza posted of the incyclider camera. Its a impressive shot of what is happening in the engine during burns.
http://www.youtube.com/watch?v=cy_yaAOKjA8

What surprises me is that all the burn is to the right at the very start of the burn, just near the inlet valve.
The length of time in terms of degrees that the burn takes to happen>
The fuel coming in is not a even mix.
And if I am brave enough it appears at the end just before the valves closes there is liquid fuel coming into the cyclinder or it could be somthing else I am not sure.

A couple of months back Bazza and I were talking and I mentioned I used to use a colour tune spark plug to tune the older engines. It let you see the color of the burn.

Tony

Dessertrunner · #**509** 12-11-2012, 06:47 PM

Slightly off topic, Harvey and my mag has a turbo engine with indiviual Throttle bodies. I don't have the artical with me but maybe Harvey you can give the guys some details.

What do you think Matt, it kind of blows me away as I still can't get my head around the logic but these guys build race engines.
Tony

oab_au · #**510** 12-11-2012, 09:18 PM

Quote:

Originally Posted by Dessertrunner

I just had time to watch the video that Bazza posted of the incyclider camera. Its a impressive shot of what is happening in the engine during burns.
http://www.youtube.com/watch?v=cy_yaAOKjA8

What surprises me is that all the burn is to the right at the very start of the burn, just near the inlet valve.
The length of time in terms of degrees that the burn takes to happen>
The fuel coming in is not a even mix.
And if I am brave enough it appears at the end just before the valves closes there is liquid fuel coming into the cyclinder or it could be somthing else I am not sure.

A couple of months back Bazza and I were talking and I mentioned I used to use a colour tune spark plug to tune the older engines. It let you see the color of the burn.

Tony

That is a two valve engine, could even have carbs on it.
The burn is moving around the chamber due to swirl and turbulence from squish.
The burn for the eg33 takes ,75* for a 100%, 50% burn takes 31*.

Hard to say if that video is during full throttle, or not, makes a difference, like the colour tune plug, hard to do at WFO throttle.

Harvey.