[1966socalgoat]

Curious what people were running, Torker II vs Victor, would the larger ports make a difference on a sequential injected build?

[Steve C.]

I'm using a Holley HP EFI Universal MPI Retrofit Kit with a Victor intake manifold. The reason for me is my 505 cubic engine naturally aspirated will make more power with the Victor intake than with a Torker II intake. Therefore I converter the Victor over to run the fuel injection.


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[1966socalgoat]

Thanks for the reply Steve. Beautiful car BTW. In your opinion do you think the Victor off idle response suffers due to the runner size?

[Steve C.]

I need to make a important correction, I did not dyno test a Torker II intake with my current 505 engine. But I have tested and compared the TII before on a previous combination and there was in my case a significant difference between the two intakes before, thus I never considered the Torker II intake for fuel injection. My apology for any confusion with this ahead of time.

And I must honestly say I made the change from a carburetor to the multiport fuel injection as more of a whim then necessity, a project that I wanted to do for many years but put off simply for the costs involved. That said the main factor more than anything in my desire for FI actually involved eliminating summer heat soak starting issues with the carburetor more than anything. It was not an extreme issue but more of a occasional annoyance.

They say one of the benefits of fuel injection includes smoother and more consistent transient throttle response. In my opinion regarding that subject, and in my specific situation, I didn't think there was a detectable improvement. Only because I never felt it was a issue prior with the carburetor. And maybe the larger 505 cubic inches could be a important factor here. When we dyno tested the 505 the first time we did so with different intake manifolds including the Victor intake and a Performer RPM intake. The difference in power between the two was VERY significant, more so than my previous 4.210" stroke 462 cid engine. But tested at the track the Performer RPM was a dog with the 505 cubic inches involved ! This engine thrived on the Victor intake. I also thought there should of been a difference between the two in low rpm driveability because of design, a dual-plane and single-plane. But on the road there was little if no difference between the two intakes involving driveability, the use of the Victor intake was a no brainer. But I must point out the HP950 carburetor was custom built by one of the best in the business and in the opinion of the fellow that tunes my car he stated it was one of the finest off idle / low rpm street carbs he had ever encountered. Also we did our prior homework talking with Holley tech and the fellow that was going to 'tune' my installed FI regarding the fuel injectors as it is very important to match the fuel injector flow characteristics to specific engine applications.


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[Steve C.]

I know my blabbering was not a specific answer to your question regarding intake design difference.

But I found this that will be of interest....

Injection position/fuel delivery system
• The volumetric efficiency of carburettors or throttle injection position is far
lower than that of multipoint injectors or Direct injection.
• This is because no air is displaced by fuel vapour
• When multipoint injectors or Direct injection is used there is no need to
have a high speed and high turbulence(lower diameter and longer runner
to increase friction).
• The above will increase the volumetric efficiency even further because the
biggest possible runner diameter will be used.
• Note: Although the later the injection in the intake manifold the better the
volumetric efficiency, late injection might mean that the fuel didn’t mix
well and could compromise combustion quality. May be this isn’t the case
in modern engines .

Source: http://site.iugaza.edu.ps/talrayyes/..._Chapter-5.pdf

And as I mentioned the size of the engine and its air flow requirements will be a factor. With that in mind is intake runner length and/or runner volume a big factor with direct port fuel injection ? The Torker II average runner length is 6.06" and the Victor is 6.82". The average runner volume for the Torker II is 236 cc's vs 346 cc's on the Victor intake.

Now the effects of plenum volume between the two intakes might be misleading, the average volume of the Torker II is 1195 cc's and the Victor 946 cc's. But what might lead to the difference being misleading is the design within the plenum of the Victor intake itself and that is the protruding distance and effects of the four "wings" sticking out into the plenum vs the design of the Torker II intake. Different internal shape affecting the volume, but how do they compare in height that could (?) have an effect.


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[1966socalgoat]

Thanks Steve, I appreciate your insights and the time. I have a Holley terminator TB now on Hurricane Single Plane but would like to go sequential. I ran sequential before with a Megasquirt system a few years ago but I couldnt get my timing control to what i wanted.

I am pretty happy with the Holley now but just looking at another project, another thought is dual TBs on on an offy maybe or using a Mopar Tunnel Ram as a base.

[Steve C.]

Your welcome. I'm surprised others didn't chime in as I'm certainly no fuel injection expert, only what I read. I know Lee Atkinson often comments and he is pretty darn savvy when it comes to the subject.


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[JLMounce]

I think the simple answer here is to utilize the intake that you need in order to adequately feed your engine. Steve C mentioned the air mass, which for a multi-port EFI setup is less as you have the air mass only, without atomized fuel.

Additionally, with the MPFI you don't really worry about runner signal to the throttle body (this is actually true of throttle body injection as well) so your runner design doesn't have to take that into account. What this typically means is that a manifold or runner design that might otherwise be lazy while using a carburetor would improve through use of the EFI.

There's some pressure wake tuning that I've read about but don't understand that occurs in the runner and acts as a scavenge effect in the plenum that occurs with EFI runner tuning, but at the point you start doing that, you're probably also working with the intake and exhaust ports and exhaust tube design as well. For street purposes you kind of have the intakes that are available and whatever mods you can then do to them from there.

I run a torker ii on my FiTech injected +.030 455 and it doesn't lack throttle response or power production, even at low rpm. At slow actual speeds and the transmission in 3rd gear, you can feel the roll on of power as the cam and intake starts working more together, but it's never lacking or lazy feeling. This is of course not an apples to apples comparison to MPFI however.

That said, my experience with modern cars has typically been that upstream intake modifications to allow more air tend to work without much if any compromising effect. Since you don't need a good signal to a carburetor, going bigger upstream of the intake port kind of just allows the intake port to intake what it wants/needs. As a result, if your engine's CFM requirements are towards the top of what the torker ii can provide, I don't believe that going to the victor manifold would cause an incredible loss in low rpm torque production.

This is only my observational evidence though and I could be off base on it. I tend to get long winded, but my overall point would be for a street style build to use the manifold that best fits the combination in a more traditional sense.

[Steve C.]

Another interesting topic is camshaft design and specifications with the different types of fuel injection systems. Not fully understanding this subject I had it in the back of my mind a wider lobe separation was "better" with fuel injection. Not long before we made the change to fuel injection I damaged one lobe on my camshaft due to a roller lifter issue. Knowing we were going make the switch to the fuel injection when I ordered my new cam I went from a 110 lobe separation to a 112, other than this all the other specs remained the same. Right or wrong I cannot detect any difference except the idle sound is ever so slightly different. To me it drives the same on the street.


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[455HOGT37]

Originally Posted by 1966socalgoat

...I have a Holley terminator TB now on Hurricane Single Plane but would like to go sequential. I ran sequential before with a Megasquirt system a few years ago but I couldnt get my timing control to what i wanted...

I'm new to the aftermarket EFI game - my only experience being the system I'm installing on one of my airplanes- but it was my understanding that these systems were not sequential. Individual ports, yes, but they all fired at once. Thats how my system works anyway. For true sequential (port timed) you need cam position and about 100x the lines of code at a minimum. Can anyone confirm or deny?

[1966socalgoat]

You are correct you need cam and crank position to do it. Now there are dual sync dist available. When i first did sequential I could not get a good sync from my cobbled up cam sensor. What you describe is batch fire which does work but Holley HP can do sequential and you can even adjust injector firing to crank position I.e. TDC etc.

[455HOGT37]

Good to know. Thanks!