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 Post subject: Dyno time
 Post Posted: Mon Oct 29, 2012 5:33 pm 
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Location: Auburndale, Florida
I had the pleasure of working with Kevin Willis and Dave Young from Mopar Muscle Magazine. We tested a stock bore 10:1 440.

We ran the stock 915 heads, a set of unported, and a set of ported 440 Source aluminum heads. We ran an old Edelbrock TorquerI, Mopar M1, Edelbrock 440 Torker, Holley Strip Dominator, and some sort of Indy manifold. The Edelbrock 440 Torker came late so they were only run on the unported aluminum heads.

Carbs were a new style Holley Ultra 950 and a Holley 8896 reworked by QFT to a 1.72 throttle bore and QFT 3 circuit metering blocks.

The ported heads with the Indy intake and the 1050 made the most power at 525Hp and 460tq. Next was the 440 Torker with the 950 at 481HP and 470 Tq.

The stock heads, TorkerI and the 950 made the best all around street drivable package. We used 93 octane fuel.

In all we made 41 pulls over a period of 3 days.

I think you can see more at the magzine web site. Who knows you might see my ugly mug.

BTW I wasn't allowed to work any magic on the carbs. That wasn't the point of the article. I can tell you I was impressed with the 950.

Questions?


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 Post subject: Re: Dyno time
 Post Posted: Mon Oct 29, 2012 8:30 pm 
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Bruce were you able to "map" those carbs? :-k


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 Post subject: Re: Dyno time
 Post Posted: Mon Oct 29, 2012 9:24 pm 
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The Ultra carbs were mapped here.
viewtopic.php?f=6&t=9417

I think he had mapped the QF Dominator as well, seems I saw a sheet floating around somewhere he gave me... :-k


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 Post subject: Re: Dyno time
 Post Posted: Mon Oct 29, 2012 10:20 pm 
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Yeah I have a question. On the dyno runs were any of the power curves erratic at all or were they perfectly smooth lines?


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 Post subject: Re: Dyno time
 Post Posted: Mon Oct 29, 2012 11:12 pm 
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I need to make a correction. The Holley intake was not a Strip dominator but, a Street Dominator. It was the only two plane manifold of the lot. Also it was a solid flat tappet with .570ish lift and 278 at .050. The entire valvetrain was Comp Cams from cam to rocker arms and shafts.

Obviously, I'm relating this from being there as I don't have copies of the dyno sheets. The author has those.

I don't recall any of the power curves being erratic except the unported head valve springs would fall off after 6200 RPM. The ported heads were good for 6400.

Fuel curves were smooth with front and rear fuel flow tracking each other. Again, the two plane was the exception.

The 1050 put a nice fat bulge in the torque curve.

All for now it's past my bed time.

We also tested spacers. A Wilson 4150 2" merge spacer made 484HP and one of those ProForm/QFT 1" changable spacers made 481hp with the open spacer. The Wilson spacer made 10 more average HP and 10 more average torque.


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 Post subject: Re: Dyno time
 Post Posted: Tue Oct 30, 2012 8:10 am 
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The 950 carb we used in the test was the same one I had mapped in a previous thread. The 1050 was one that was left over from some article a couple of years past.

Manifold swapping is pretty easy on these big block Mopars. Lift the carbie, take out eight manifold bolts and swap. I can't imagine doing all these swaps on a Chevy with having to drain water and the removal and reinstallation of the distributor.

A little more about the engine:

As stated it's a stock bore 440. It's been sitting in the authors garage for a while but, had previously been a bracket race engine. We weren't sure it had forged pistons until we pulled the heads. Timing settled at 36 degrees. The engine showcased Comp Cams shaft rocker setup, pushrods, and the Holley Ultra carb. It would idle at 900 easily. The headers were Hookers.

The 950 was so fat it required the Mj to be reduced from 92H to 90H jets. This carb has a .072 PVCR front and rear. Even at these MJ and all the emulsion it has AFR was just about 12.1 for all the runs. It really needed to be leaned some more. Time didn't allow that. AS I recall the BSFC averaged .484 generally. I would have loved to plug my calibration in it to see what would happen.

The 1050 required that I fatten the idle circuit a bit just to get it to idle correctly.

The questions I now have are:

Is the 950 emulsion/Main jet package something I should investigate? I mean the carb ran well even if it was fat. Are we missing something here?

The 1050. It's no secret I've run a 3 circuit on my car for a while in an effort to learn more about them. Most everyone else here have run 2 circuits, and done very well with them. I've run my best with one.

This Mopar also did great with the 3 circuit we used on it. It and my engine are 100 cubes different. However, they both have compression in the low 10:1 range. They've both run 93 octane fuel, which is the only similarity.

So the questions are: Do high compression engines running race gas do better with 2 circuit carbs and do 93 octane engines run better on a 3 circuit? Would this difference be tied to the combustion chacteristics of the respective fuels?


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 Post subject: Re: Dyno time
 Post Posted: Tue Oct 30, 2012 11:47 pm 
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nomad wrote:

The questions I now have are:

Is the 950 emulsion/Main jet package something I should investigate? I mean the carb ran well even if it was fat. Are we missing something here?

The 1050. It's no secret I've run a 3 circuit on my car for a while in an effort to learn more about them. Most everyone else here have run 2 circuits, and done very well with them. I've run my best with one.

This Mopar also did great with the 3 circuit we used on it. It and my engine are 100 cubes different. However, they both have compression in the low 10:1 range. They've both run 93 octane fuel, which is the only similarity.

So the questions are: Do high compression engines running race gas do better with 2 circuit carbs and do 93 octane engines run better on a 3 circuit? Would this difference be tied to the combustion chacteristics of the respective fuels?


-
I have actually been continuously answering questions like these but there disguised in different forms. The answer is the same things I’ve always said but its the implications and the interactions of the different things I talk about that is hard to understand for anyone. You have asked a good question as I can now describe the scenario of interaction.
This sentence "Is the 950 emulsion/Main jet package something I should investigate? I mean the carb ran well even if it was fat. Are we missing something here?"
What this is an example of what happens in engines of low compression. When you run 10 to 1 with a large duration cam you actually don’t get much compression at all. Compression basically only starts once the intake valve is closed so the longer duration cams don’t give the cylinder much dynamic compression. As I have said before, it’s the compression rate and the time of compressing the mixture that largely determines the mixture preparation existing at ignition time, and also the amount of energy needed from the flame front to prepare the mixture ahead of the flame front during the burn.

The mixture preparation achieved at ignition time determines the regularity of the flame kernel and the strength of it. With street fuels there are lots of heavy Hydrocarbons that have high boiling points. These are cheap chemicals and there low octane chemicals. The 950 carby ran well even though it was fat because it delivered a large droplet to the engine. The large drops don’t vaporize all the fuel prior to ignition because there isn’t the compression in the engine to do that. Street fuel has too high a final distillation temperature to get the job done with just 10 to 1 on a large duration cam. So you get the first stage of the burn in a leaner environment than the average of the chamber. Look at the plugs and they will be whiter than what you would expect for such a rich ratio. The plugs are whiter because there operating in a lean environment. If the fuel manages to get burnt or turned into a gas by the time it gets to the Wideband sensor you will read the correct AFR of what the carby gave to the engine but its not what the engine is running on at all stages of the burn in the cylinder. When the fuel droplet is large you can get a lot of power from street fuel because your only using the low temperature chemicals which are the expensive high octane, low boiling point ones. The rest of the fuel you chuck away or turn it into bore wash and oil contaminants. IF you give the engine fine droplets on street fuel and you keep going finer and finer you eventually go backwards. That the point where you have started to gas the heavy HC’s too early in the process and the engine will start to detonate. With street fuels you need the heavy HC’s to come to the party after TDC but not too late. Thats what droplet management and ignition timing and exhaust retention is all about. Exhaust retention is a method thats dangerous to use in excess, but it provides ample energy for vaporization when the compression is low for the cam size. That’s why some people swear by exhaust tuning etc.
They know there method works for them but they may not be correctly understand why.

This paragraph” This Mopar also did great with the 3 circuit we used on it. It and my engine are 100 cubes different. However, they both have compression in the low 10:1 range. They've both run 93 octane fuel, which is the only similarity.”
3 circuit carbys have that piss and dribble 3rd circuit, it doesn’t provide as finely atomized fuel as the booster. Its that blend of droplet size that makes all the difference to some engines. Like I said above fat drops on low compression street fuel with big cams is the way to go for quick instant answers. 3rd circuit gives you that.
Using race fuel is a different matter to street blends. Race fuels have much lower top end distillation temps. Nearly half what a street fuel is, so its much easier to gas the entire molecule set of the fuel. But if the use the wrong blend you put yourself back into the same boat as street fuel, you only use ¾ of the molecules and you chuck the rest away as bore wash etc. Most racers use way too high octane fuel than they truly need and the fuel companies are happy they do. Understanding what your vaporization level of your race engine is and what octane you need to make it safe and powerful is only discovered by vaporization and homogenization control.
Correctly identify the efficiency of those 2 parameters and maximize them, then you can go (sometimes as high as) 3 compression ratios higher than expected on your current race fuel, or you can run a cheaper fuel etc. But tuners are not training themselves to know this stuff. You cant do it without a gas bench. Tuners now days get you an AFR number and go home, that’s not tuning, that’s parts swapping.

Finally to this--“So the questions are: Do high compression engines running race gas do better with 2 circuit carbs and do 93 octane engines run better on a 3 circuit? Would this difference be tied to the combustion chacteristics of the respective fuels?”

High compression engines running race gas do better with 2 circuit carbys because they don’t need the piss and dribble from the 3rd circuit. The closer the engine design is to efficient usage of the fuel the more accurate the fuel choice has to be and the more accurate the timing has to be and the more vaporization becomes important. When the planets line up inside your engine it goes the same in most weather conditions, it never gets hot, it never dirties the oil, it doesn’t wear the rings. The 3rd circuit carby doesn’t allow you see how good a good race engine can be because the fat drops mask issues of engine design. With fat drops you can get a lot of power, sometimes more than fine drops, but you can never achieve the other engine benefits with fat drops. None of this has anything to do with melting headers off.
A 2 circuit carby on a well designed engine combo is the optimum carby because it doesn’t muck up or mask the burn with fat drops. You can see how the engine is performing better and you have an easier time tuning it at the track. With three circuit carbys you can add or remove fuel from the piss and dribble circuit and experiment with droplet blending that way but your stuck with the restriction in the main well so your limited in power from the fine drop part of the carby. One of the custom manufacturers has fixed that issue, I cant remember who it is but their idea is excellent.
There is a place for both 2 and 3 circuit designs and either can be made just as successful as the other but it depends on the engine design. An engine with reduced vaporization compared to another similar one will at initial development prefer a 3 circuit. But once its developed further with more compression, better cylinder fill etc it will require a different droplet management strategy, and it’s the choice of carby design thats used to provide that.


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 Post subject: Re: Dyno time
 Post Posted: Wed Oct 31, 2012 2:36 am 
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This is the basic scenario of combustion in a cylinder from start to end.
1. Fuel is converted from liquid form to gas form. The amount of chemicals that are converted prior to ignition determines the regularity of the flame kernel and the strength of it. The temperature of the air during the compression time determines the number of fuel molecules that are heated via convection and turned to gas ready to burn.
2. Its not enough to just work on vaporization, the fuel molecules have to be spread throughout the chamber in a homogenous state. In designs for emissions it is deliberately done to create lean areas in the center of the chamber and a different mixture at the sparkplug and the outer areas of the chamber. The jury is out on the effectiveness of these approaches. For racing the approach is for an even spread of mixture because that allows a consistent tune throughout the chamber. In other words the design should prevent you from having to correct a lean detonation in one area by flooding it stupid elsewhere to bring the problem area under control.
3. The spark ignites the mixture present at the plug location. The initial flame growth is a laminar flame. Its laminar until its approx 12mm diameter. It takes approx 10 degrees of crank rotation at ANY RPM to achieve that diameter. The AFR of the mixture has hardly any effect upon the flame during its laminar stage. The burn speed is smooth and consistent during laminar flame. The burn speed is variable with the RPM but its not variable per event due to any factors like AFR Its varied a little bit by the vaporization because a droplet of un-vaporized fuel hit by the laminar flame front absorbs energy from the flame. Anytime energy is absorbed from a flame the flame speed is slowed. The arc energy is the most influential factor to the flame kernel. The energy field from an arc of the power of a crane HI-6 is approx 6mm radius. That’s the size of the laminar limit of the flame kernel. The power of the ignition is paramount to vaporizing the fuel load in that zone and achieving a stable flame kernel under high RPM conditions. The flame kernel is basically unstoppable once it reaches 12mm diameter.
4. At 12mm diameter and beyond the flame changes to a turbulent flame. Its starts to fold over on itself and looks like one of those bed donnas, quilts or cover things that are made of pockets of insulation type material. The pockets formed from stitching is what the flame starts to do, it forms that way from advancing and slowing rates within the original laminar form. Its like a stage of transitional flow in a pipe. It is at this time that mixture can be injected into the flame from areas like the squish bands. Injecting this fresh mixture into the fledgling turbulent flame supercharges its burn rate, its takes off ridiculously fast once you shove the squish in there.
5. The now fully turbulent flame is now at near TDC piston position and its burnt about 60 to 70 % of the mixture mass. Its at this point that you need to consider if your fuel has low octane chemicals in it(eg street unleaded) and you should start to gas them now so that if they decide to detonate they will at least be doing it on the power stroke and the detonation energy could be used for advantage. Does this wring a bell in your head about how one particular EMC winner for years was doing it?
6. By 14 to 18 degrees after TDC the mixture should be about 90 to 90% mass burnt and the cylinder should be at max pressure. It varies in position because of rod ratio and things like that that effect the mechanical efficiency of the engine and the location of your particular engines best peak pressure point. (PPP) But the PPP is in that Zone. That’s why we have computers to adjust the ignition timing so we can fiddle around in the top end and find the PPP.
7. Note at the PPP we have not completely burnt the fuel mass,we have only burnt 95% of it. That’s because we need the remaining 5% to chase the piston down the bore and to provide some energy to the exhaust pulse. If we don’t have enough energy for the exhaust pulse we cant scavenge the cylinder ready for the next charge. You can alter the exhaust pulse energy in many ways. Anything that alters the valve opening point, anything that changes burn time, anything that alters burn percentage at PPP, and the list would go on and on.
8. All this time some of the burn energy is going into the water jacket and some energy is transferring to the piston. If the piston is ascending, then that part of the energy is returned to the chamber and its used to keep improving the burn (hopefully, and not to start melting stuff) If the pistons descending then its converted by the crank/rod assembly to torque.
9. The unused energy from the burn (that which is not converted to torque etc) is exhausted as heat and pressure and speed of gas flow. We measure with thermocouples the temp and discuss in the pits if its rich or lean etc but in reality its rubbish. We should be discussing if we have enough exhaust retention or removal from the chamber and we should be discussing if the gas is CO or CO2 and we should be discussing if the gas temperature is assisting us in vaporization of the next charge and asking if there a better way that may have some advantages with less of the disadvantages of retention. Reading the spark plugs is a way to start discussing these factors.


With engines of low compression and big cams, exhaust retention can greatly improve power, depending on the fuel your running. Go play with 2 stroke engines which actually have very low compression, and see how effective the exhaust is to those engines.

The whole purpose of an engine is convert chemical energy to mechanical energy. If you have to add heat to the mixture via the exhaust restriction to get a better overall burn then so be it.
It’s the chemistry of the burn that determines how much power per unit of air you pump through the motor. Chemistry switches molecules off and on at defined energy points, it’s the energy management of those molecules that you control by having so much compression or a certain cam or advancing and retarding it or bigger or smaller carby etc. The effect of molecule energy input is observable on tools like gas benches, oscilloscopes, and in cylinder pressure measurement. A gas bench and scope and dyno and a sharp eye with an open mind on operating changes is what you need to figure engines out.


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 Post subject: Re: Dyno time
 Post Posted: Wed Oct 31, 2012 4:50 pm 
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viewtopic.php?f=6&t=9547 This carb (3 circuit) worked well on a 14-1 motor , he bought the carb. I tuned an older HP for my 10.5 - 1 street motor (very similar tune up) and it worked well too??


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 Post subject: Re: Dyno time
 Post Posted: Wed Oct 31, 2012 5:00 pm 
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Milan.. wrote:
This carb (3 circuit) worked well on a 14-1 motor , he bought the carb. I tuned an older HP for my 10.5 - 1 street motor (very similar tune up) and it worked well too??


Yes but did you try it against a working 2 circuit??

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 Post subject: Re: Dyno time
 Post Posted: Wed Oct 31, 2012 5:14 pm 
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No I did not , I wish I had a 2 circuit to try , Im sure it would work fine , the 1150 on my race car does , but just too big (and it worked so well I did not want to mess with it) for a street deal .....thinking the "piss and dribble" worked good for 14-1 and 10.5 - 1


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 Post subject: Re: Dyno time
 Post Posted: Wed Oct 31, 2012 8:11 pm 
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Its not just the compression ratio thats related to the piss and dribble. Droplet size is how you control the vaporization rate. Obviously larger droplets take longer to turn to gas. The process of turning to gas is the whole intake track not just the little bit of time spent in the cylinder.
Lets break it down.
1- The time spent traveling in the barrel of the carby, is the first part of the process, what is the venturi tail shape? the throttle shaft disturbance? Is the throttle shaft part of the venturi tail? Things like this have effect on the pressure in the venturi tail and carby exit and that all effects the vaporization of the droplets.
2- What is the environment in the intake manifold, does the intake manifold have exhaust reversion present from when your just idling around and now you have stomped on the throttle? How long does the engine take to clean out the plenum? Is there a cylinder that's feeding exhaust back pressure to the manifold greater than others due to exhaust pipe design? There always is. So how much heat is there in the manifold, what is the vacuum in the manifold. It all effects the vaporization and droplet size that gets past the valve curtain.
3- The valve curtain area. Biggie this one. Hot valve, high speed air flow, low pressure, lots of stuff to smash into. The piston air demand and how it interacts with the valve lift profile creates such varied conditions for the fuel flow and its vaporization. Its not calculable but its easy to spend a little time thinking about what would be happening and its obvious whats going on there.

Just remember that lowering the pressure gases more of the fuel, increasing heat gases fuel, reducing droplet size gases fuel. When the fuel is gas it follows the air flow better and goes where the air goes, when its a liquid state it doesn't follow the air well. You want the fuel to go where the air goes because that's how you get a homogenous mixture and an even burn that you can tune without compromise.

So the whole process of vaporization and where it occurs is what the burn in the cylinder is a result of. An engine that's high compression can benefit from piss and dribble if its got design ideas that create too much vaporization. TOO MUCH vaporization is a bad thing. Gasoline's are very complex with not completely known reactants in the mix. If you completely vaporize gasoline that has some molecules that detonate easily but are high temperature boiling point your completely vaporized state will enable these undesirable molecules to react earlier in the burn process than normal. Whereas they should still be liquid or boiling away slowly decreasing droplet size and slowly feeding molecules rather than having a lot of them all detonating at once.With detonation Its not just that your fuel supplier is no good with lousy molecules, it could be your engine is creating them. Any time a burn is interrupted part way the molecule left behind is an unknown one. If its doesn't get exhausted it hangs around for another go at it. That's what a free radical is. Its an unknown, probably dangerous, HOT molecule ready to bang too early on the next time around.

If you use Methanol you have a fuel that is all made of the one molecule, unless you add something to it. You may think that a simple fuel like that would be nearly perfect and not create free radicals etc because its such a simple molecule to break down and 'how could it create lots of combinations'. Well it so happens that during a burn, complex molecules are created from simple ones. Bugger. So fuels create there own chemicals that were not in the original supply!!! YES YES YES and its all part of the same engine design errors that stop the completion of the burn of a molecule.

The droplet size is a way to cool the peak temperature and extend the burn to last longer, add some piss and dribble and it slows the burn and holds the cylinder pressure to a different area under the curve, not such a peak but more of a steady push.
Sort of like a black powder rifle compared to a Centerfire. You gun guys will get that one.


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 Post subject: Re: Dyno time
 Post Posted: Wed Oct 31, 2012 9:46 pm 
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Thanks for the explainations shrinker. For clarification I am running the BLP wide body 3 circuit metering blocks. These, for others information, have no idle tube in the main well.

On these metering blocks the intermidiate jet is smaller, .035 as opposed to the .040 plus, that I have seen in genuine Holley blocks. It must still be enough as I only run .118 BLP main jets.

I have tested both 16 hole and 12 hole booster inserts in my engine. I can tell you it seems to like the 12 hole better. I'm wondering if this is related somehow to your lesson above.


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 Post subject: Re: Dyno time
 Post Posted: Wed Oct 31, 2012 11:12 pm 
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What you see with 12 hole and 16 hole is telling you that your engine likes larger drops and its for the reason I said above. Its is more complicated than what Ive written but that is the basics of it for people to understand. If they wish to chase it further there is plenty of proper scientific papers on the subject. BUT only read proper papers, not stuff written on web pages. There all the same junk repeats.
Seek out information on mixture ranges between droplets, that will make you think.

Even with the scientific papers there are problems, most of the researchers dont understand enough of other subject areas to do a proper isolated test. There has only been one I couldn't fault, it was done in the 40's. the old guys new their s**t. Now days a lot of stuff done via computer modelling or its research to obtain the rules of a model. I hate that stuff, its not correct in so many ways its ridiculous. The real world is what you have work with, with real difficult to make and perform experiments not virtual math models with faulty incomplete maths inside a computer. We dont understand enough of the variables to make anything close to a math model so all that research is worthless in my book.


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 Post subject: Re: Dyno time
 Post Posted: Thu Nov 01, 2012 6:46 am 
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"Piss and Dribble"
I have to remember that one! =D> =; =D> =; =D>


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