rmchrgr
Skate And Destroy
Sounds good, will be interesting to see what you wind up with.
Holley Strip Dominator vs. Edelbrock Victor 340
- Thread starter rmchrgr
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Sounds good, will be interesting to see what you wind up with.
rmchrgr
Skate And Destroy
I have also been looking at somehow increasing my compression ratio. I do believe I'm on the low side at 10.3:1. Pistons are true zero deck with a 21 cc dish. The chambers are 62 cc, .0039" head gasket. Not sure exactly what effect the various intake designs would have on a slightly higher compression ratio but it can't hurt.
Rat Bastid
Dunamis Metron
Get yourself one of those Magna Fuel anti reversion plates and se the gasket they send with it to for the the SD carb flange.
The SD will have more area under the curve and therefore more average power.
There isn’t a cast single 4 out there on 400 plus inches that has enough runner size. Not one. S se what you have.
Those Magna Fuel plates work better than any other 4 holed spacer, because it’s not a spacer.
The SD will have more area under the curve and therefore more average power.
There isn’t a cast single 4 out there on 400 plus inches that has enough runner size. Not one. S se what you have.
Those Magna Fuel plates work better than any other 4 holed spacer, because it’s not a spacer.
justinp61
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No welding or epoxy, just time with a die grinder.
rmchrgr
Skate And Destroy
I've read up on anti-reversion/shear plates a little. I don't know if one would do much in my particular application. #1, the Strip Dominator has the spread bore so I have a feeling it wouldn't fit without a LOT of grinding. Plus, I believe those things were initially designed to be used on tunnel ram or sheet metal type intakes.
I also have no clue how EFI would handle it but probably wouldn't hurt any since FI adjusts to what's there, whatever the configuration under the throttle body might be - single or dual plane intake, tunnel ram, long or short runner, spacer, shear plate, etc. The fuel mixture is obviously controlled electronically so if there is a 'problem' area then you go into the fuel tables and adjust accordingly. It's never perfect but you can get things fairly close to whatever target A/F ratio you choose for a given data point.
I think the FI can be a big help in tuning for situations like street driving with a healthy cam and single plane. You can 'band aid' it so it doesn't load up or whatever then change the tune when you go to the track and let it fly. Yeah, it takes time just like anything else and you need to understand what's going on at whatever point you're trying to work with but it's useful to have the ability to adjust singular data points without altering the entire fuel curve.
I also have no clue how EFI would handle it but probably wouldn't hurt any since FI adjusts to what's there, whatever the configuration under the throttle body might be - single or dual plane intake, tunnel ram, long or short runner, spacer, shear plate, etc. The fuel mixture is obviously controlled electronically so if there is a 'problem' area then you go into the fuel tables and adjust accordingly. It's never perfect but you can get things fairly close to whatever target A/F ratio you choose for a given data point.
I think the FI can be a big help in tuning for situations like street driving with a healthy cam and single plane. You can 'band aid' it so it doesn't load up or whatever then change the tune when you go to the track and let it fly. Yeah, it takes time just like anything else and you need to understand what's going on at whatever point you're trying to work with but it's useful to have the ability to adjust singular data points without altering the entire fuel curve.
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rmchrgr
Skate And Destroy
Got any pics?
Rat Bastid
Dunamis Metron
I forgot you are using EFI. If that’s the case, just make the carb flange square by grinding it to the size it is on the secondaries.
Here is a picture of the carb pad opened up.
pishta
I know I'm right....
^^ is that Dominator series carb ready?^^
problem with adapted EFI (if any) is the popularity of the TBI style on older intakes and the thought that its as good as it gets. The nice thing is the intake on a MPFI can be almost any shape as it only flows lightweight air, no fuel. The fuel is injected at the last inch of the intake tract. You have no distribution problems, lean cylinders, etc. if everything is working. You can also get some really long runners without puddling for large torque gains in the lower RPMs and a ram effect in the upper range.
problem with adapted EFI (if any) is the popularity of the TBI style on older intakes and the thought that its as good as it gets. The nice thing is the intake on a MPFI can be almost any shape as it only flows lightweight air, no fuel. The fuel is injected at the last inch of the intake tract. You have no distribution problems, lean cylinders, etc. if everything is working. You can also get some really long runners without puddling for large torque gains in the lower RPMs and a ram effect in the upper range.
Rat Bastid
Dunamis Metron
rmchrgr
Skate And Destroy
Agree that retro fit TB style FI is not an ideal solution. I mostly like it because of the software. As I mentioned already, the ability to adjust singular data points or at least smaller areas of your fuel curve without affecting the entire thing is a nice feature.
I'm also a believer in the benefits of higher fuel pressure and digitally controlled ignition timing. There has to be some level of efficiency gained by spraying fuel into the intake tract at 60 psi vs. pulling it out of the fuel bowls behind 6-7 psi. Controlling timing digitally takes the mechanical tolerances out of the equation and provides a more accurate and stable spark over the rpm range. A crank trigger is the next evolutionary step up, I'm not there yet.
Truth be told, I am definitely not a carb tuning expert. Can I get a car to idle OK and tune out bogs? Yes. Can I find hidden power? No. When I dynoed my engine however many years ago, I used an OOTB Proform 850. About the only thing that was done carb tuning-wise that day was go two steps down on the jets which did not result in anything except leaning it out a half a point. No spacers were tried, no air bleeds were changed. No clue how much power it was leaving on the table but I'd guess it was a significant amount. The BSFC numbers were higher than what they should have been for the amount of fuel it was observed consuming. Whether the dyno apparatus was not calculated properly or something inherent in the engine combo itself was mismatched will forever remain a question unless I decide to go back and re-do it.
Can I find hidden power with EFI? Probably not but I like to think that I've gotten farther with it than I ever did with a screwdriver and either my ear or the seat of my pants. I've had it on my big block Coronet for a while now and I am confident in saying that it runs light years better than it ever did with a carb. I hold no illusions that it makes more power but it does seem to run crisper and cleaner. Take that for what it's worth.
I don't want to get too far off topic here but some of this background info is relevant.
Rat Bastid
Dunamis Metron
Fuel pressure isn’t responsible for moving fuel out of the booster on a carb.
That’s why there are different styles of boosters so you can control how well (or not depending on what you want to do) the fuel is atomize leaving the booster.
That’s why there are different styles of boosters so you can control how well (or not depending on what you want to do) the fuel is atomize leaving the booster.
justinp61
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I don’t, but the intake is off if some are needed.
rmchrgr
Skate And Destroy
That's why I said "behind" 6-7 psi. The fuel pressure in a carb is basically just an aid to keep it "primed" I guess when the signal pulls it out. The booster atomizes it. The difference is that EFI relies on fuel pressure to push it out of the injectors. I was also guessing at that so based on what I linked to below, my idea that it's more efficient to spray the fuel at higher pressure vs. pulling it out of the bowls may be incorrect.
I don't know how annular vs. dog leg makes a difference as far as what the intake sees or perhaps how it performs once the fuel is suspended in the air. Does an annular style booster provide a better "shear"? We're kind of splitting hairs here but you know, just for kicks...
Thinking about that idea, I found an article written a little over 12 years ago. Retro fit EFI has come a LONG way since then so I take this article with a grain of salt. It does talk about the difference in atomization between the two systems.
Caburetors and Electronic Fuel Injection Systems
"The carb has a proven advantage over EFI in most applications according to Hilborn Fuel Injection’s Andrew Starr. “We have found that when comparing a common plenum carb to common plenum EFI, the carb typically makes more power,” Starr explains. “This is because the booster of the carb shears the fuel into fine droplets, allowing it to mix and stay suspended in the air column inside the manifold. This reduces the chance of the fuel droplet falling out of suspension and makes for a better burn in the combustion chamber. EFI on the other hand sprays the fuel under pressure, which is not easily picked up by the moving air stream. Coupled with all of the reversion pulses inside the standard common plenum intake, this promotes fuel separation, reducing combustion chamber efficiency.
"The only time we really see a marked increase in power with EFI over carburetion is with the use our individual runner manifold, which offers greater air speed over our common plenum along with the lack of reversion. This also allows combinations with cams that would be considered too large for normal street driving to have excellent low speed torque and excellent part throttle drivability. It is not uncommon for one of our injected engines to make 60+ rear wheel horsepower over a carburetor."
The article does mention reversion so maybe an anti-reversion plate is something worth investigating. Reading between the lines in the 2nd paragraph (disregarding the idea they're talking about individual runner manifolds) kind of confirms what I was saying that previously less-than-ideal situations can be made to work a little better on the street than with a carb.
rmchrgr
Skate And Destroy
That would be appreciated when you have the time. I think the notion that the Victor 340 "needs a lot of work" to get it up to it's potential comes up a lot on the forums so it might help someone in the future understand what needs to happen with these things even after you plunk down $457 on one.
rmchrgr
Skate And Destroy
Tried to PM but your inbox is full.
Its a may or may not. Depends on what the heads and cylinders can suck down. Even if it does add more into the cylinder, the word “Compliment” is a word I don’t understand above, in its usage?
BUT
Let me say the amount of exhaust increase due to a better intake isn’t a massive issue as you may think.
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justinp61
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It should be good now. For what it’s worth I don’t have any before photos of the intake.
rmchrgr
Skate And Destroy
What I am trying to ascertain is whether keeping the intake size the same while increasing the exhaust tube area might be less efficient than going to a slightly larger intake to fill the now larger exhaust area better. I would think it would but I don't know. I'm not an expert on port velocity vs. volume or what have you.
It's like connecting two different pipe sizes. Generally when you increase volume on one side of a pressurized tube it has the effect of slowing down what ever is being pushed through the orifice when it hits the larger area. If you keep the tube or pipe the same size on both ends, the increased volume may drop overall pressure but there won't be a change from one side to the other. I know that's not a perfect analogy because there's a lot more going on in an engine but it's not too far fetched to break it down like that.
Rat Bastid
Dunamis Metron
Your understanding of carburation is wrong. Fuel pressure and atomization in a carb are totally separate. That was my original point.
Here’s what I mean. I can run as high as 8 pounds of fuel pressure and as low as 3.5 and at no time will that pressure affect fuel atomization. That is the job of the booster.
This is why carbs get a bad rep. They are not understood, and I lay that right at the front door of HOLLEY because not only did they not advance knowledge of carburation, they hindered it (and still do) with crap tuning advice.
And shame on all the carb builders of the 70’s and on. They are just as bad as Holley for trying to make everything a secret.
Fortunately, that worm has turned. There are people out there willing to teach this stuff.
One of the best EFI guys in the country will tell you his EFI can only match the power of carb, because what he basically has is an electronic carb. The only difference is it took him a few runs to get Max power with EFI and I think he said 15, maybe 20 pulls with the carb. And I say he could have cut that in half had he bought something other than a Holley carb from Holley.
Rat Bastid
Dunamis Metron
I’m going to post a link to a webinar you won’t want to miss. I promise you the presenter will cover exactly what you are asking, and if he doesn’t, there will be ample time for you to ask him yourself.
I’ll start a new thread.
rmchrgr
Skate And Destroy
Like I said, in my mind, fuel pressure in a carb application is an aid to keep the fuel in the bowls "primed" for when it gets pulled out by the low pressure under the venturi. Plus, your fuel pump ius almost always below the carb so there has to be some way to keep the liquid from draining out of the bowls.
In any event, in a carburetor, fuel basically drips out in solid form so it needs some sort of pressure behind it to get it moving into the air column. Yes, the booster is what atomizes it. But carbs don't "need" a whole lot of fuel pressure because they're not spraying fuel, it's being pulled out from below in solid form until it goes through the booster. And what about the accelerator pump shot? That's basically a stream of raw fuel that gets dumped directly into the air column. How does that get broken up? Or when you have a choke?
I honestly don't know exactly how the fuel gets atomized by the Sniper. It's basically a digital carburetor but I know it relies on spraying the fuel in pulses into the plenum at 60 psi instead of relying on pressure differential below the venturi to pull it out. Whether that does a "better" job of getting the fuel into the air column is an engineering question that's way beyond me but based on how well it works, I would have to think there is some benefit to the higher fuel pressure.
I think both do an OK job and have their place and whether one is better suited for some particular intake configuration is based on the application. If this was an all-out race car, I probably wouldn't be running EFI because there's no part-throttle drivability concerns. But when I'm driving a car with a Ricky-Racer single plane intake and a rowdy cam on the street it's nice to know that have the ability to prevent excess fuel from dumping into the cylinders and washing the oil of my cylinder walls and bearings.
Fuel atomization: Carb vs. EFI
Rat Bastid
Dunamis Metron
I remember that thread. And there was a bunch of guys getting it wrong there too.
Go to YouTube and search Darin Morgan and watch his videos on fuel, atomization, wet flow and such.
Way better than that thread.
Post 63 & 72.
EFI & carb work on exactly the same principle: pressure forces fuel into the air stream.
- With a carb, it is atmospheric pressure doing the 'pushing'. 14.7 psi at sea level
- with FI [ or EFI ] it is pressure generated by a pump.
Claims of carbs making more hp than EFI [ or vice versa ] are unreliable as to how much hp YOUR combo will make. Too many variables, you have to try it.
EFI & carb work on exactly the same principle: pressure forces fuel into the air stream.
- With a carb, it is atmospheric pressure doing the 'pushing'. 14.7 psi at sea level
- with FI [ or EFI ] it is pressure generated by a pump.
Claims of carbs making more hp than EFI [ or vice versa ] are unreliable as to how much hp YOUR combo will make. Too many variables, you have to try it.
Rat Bastid
Dunamis Metron
No, posts 63 and 72 are NOT correct. Read the whole thread. Fuel pressure on a carb has ZERO affect on atomization. None.
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