Victor Jr EFI vs. Fast 90
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Robert
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FYI.. I have some dyno time owed to me (work trade out for doing some local work). I was planing on testing:
Stock LS6 with ported TB (Currently on the truck)
Stock Fast 90/90
Stock unported Vic JR with ported stock
Stock unported Vic JR with 90
Stock unported Vic JR with 105
Stock unported Super Vic with ported stock
Stock unported Super Vic with 90
Stock unported Super Vic with 105
Test bed is a forged 347ci motor
ABS heads
--------- In-------EX
0.200----149-----112
0.300----208-----169
0.400----257-----201
0.450----276-----211
0.500----288-----219
0.550----296-----222
0.600----306-----226
Trex
4L80E w/ fuddle 4,400 verter
12 bolt with 3.73's
30x13.50 ET Street
Current dyno with LS6/Stock ported:
![](http://73-ls1.com/63truck/new_tune_11_27.JPG)
I need a Super Vic and if someone like Tony wants to throw a ported 90/90 in to the mix, I'll be glad to send it back when done. I have my motor apart right now waiting on head gaskets and studs but they should be here I would think by next week. I could probably slate the time to do the testing towards the end of the month.
All testing on the Vic's JR and Super will be with out a 90* elbow. They will be plumed straight up like a smoke stack as that's how I would run it on my truck.
Stock LS6 with ported TB (Currently on the truck)
Stock Fast 90/90
Stock unported Vic JR with ported stock
Stock unported Vic JR with 90
Stock unported Vic JR with 105
Stock unported Super Vic with ported stock
Stock unported Super Vic with 90
Stock unported Super Vic with 105
Test bed is a forged 347ci motor
ABS heads
--------- In-------EX
0.200----149-----112
0.300----208-----169
0.400----257-----201
0.450----276-----211
0.500----288-----219
0.550----296-----222
0.600----306-----226
Trex
4L80E w/ fuddle 4,400 verter
12 bolt with 3.73's
30x13.50 ET Street
Current dyno with LS6/Stock ported:
I need a Super Vic and if someone like Tony wants to throw a ported 90/90 in to the mix, I'll be glad to send it back when done. I have my motor apart right now waiting on head gaskets and studs but they should be here I would think by next week. I could probably slate the time to do the testing towards the end of the month.
All testing on the Vic's JR and Super will be with out a 90* elbow. They will be plumed straight up like a smoke stack as that's how I would run it on my truck.
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Robert
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Robert
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The standard intake, the FAST and the Victor Jr are all single plane designs. Dual Plane refers to a design where each half of a 4 barrel carb would feed 4 cylinders. There was a divider in the plenium. They made better bottom end because effectively those 2 banks of 4 cylinders were exposed to a carburettor 1/2 the size of a single plane. They also had less turbulence caused by the reversion reversion pulse from the valve closing on the other cylinders.
The main difference between the design of the Victor and the FAST is the plenium is much larger on the FAST and the runners are longer.
Cheers
Michael
The main difference between the design of the Victor and the FAST is the plenium is much larger on the FAST and the runners are longer.
Cheers
Michael
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The standard intake, the FAST and the Victor Jr are all single plane designs. Dual Plane refers to a design where each half of a 4 barrel carb would feed 4 cylinders. There was a divider in the plenium. They made better bottom end because effectively those 2 banks of 4 cylinders were exposed to a carburettor 1/2 the size of a single plane. They also had less turbulence caused by the reversion reversion pulse from the valve closing on the other cylinders.
The main difference between the design of the Victor and the FAST is the plenium is much larger on the FAST and the runners are longer.
Cheers
Michael
The main difference between the design of the Victor and the FAST is the plenium is much larger on the FAST and the runners are longer.
Cheers
Michael
I think the main difference between the FAST and Vic and Super along with the GM single plain, is the distribution, much more even with a central entrance style intake, just basic physics. Also, the LSx intakes have the plenum below the runners and the carb intakes have it above the runners and thus the different air dynamics. Don't get me wrong, the FAST from a good porter is hard to beat, but for some, the new single plains are the way to go and definitely have a great future.
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Robert
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I agree with you Robert, They will both behave quite differently with the very different shapes of the two manifolds affecting the way the air flows.
I must preface this by saying I'm no expert but I've thought a lot about the two designs.
The FAST and stock style manifolds have much longer intake runners which is proven to be better for low end performance. Shorter runners are better for top end. The volume of the plenum will have a big impact as it resonates at a particular RPM range. To my way of thinking a larger plenum resonates at a lower frequency therefore lower RPM.
The throttle body at the front of the manifold is a design compromise for hood clearance and ease of plumbing. I like the idea of a central throttle body for even airflow distribution. I guess it's not as critical now with the injectors right at the port but it used to be a major issue with carb manifold design. What i think will be a factor is the turbulence from one port affecting the flow of an adjacent port. Having a central throttle body has to be better in this regard as the flow to all ports should be more even.
Cheers
I must preface this by saying I'm no expert but I've thought a lot about the two designs.
The FAST and stock style manifolds have much longer intake runners which is proven to be better for low end performance. Shorter runners are better for top end. The volume of the plenum will have a big impact as it resonates at a particular RPM range. To my way of thinking a larger plenum resonates at a lower frequency therefore lower RPM.
The throttle body at the front of the manifold is a design compromise for hood clearance and ease of plumbing. I like the idea of a central throttle body for even airflow distribution. I guess it's not as critical now with the injectors right at the port but it used to be a major issue with carb manifold design. What i think will be a factor is the turbulence from one port affecting the flow of an adjacent port. Having a central throttle body has to be better in this regard as the flow to all ports should be more even.
Cheers
#156
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The only thing I disagree on is the plenum volume being increased will be directed at lower RPMs, not true, it's really more towards higher RPMs. Look at the tunnel rams and such, mucho plenum volume and pretty much dogs on the street, or at lower RPMs. though they can be made to work and I have run numerous dual quad tunnel rams on the street. The problem with the increase volume is we loose velocity at low speeds. meaning, the capacity capabilities of a high plenum volume intake will in fact slow way down at low RPMs and thus become a problem. however, it's not as big of a problem with EFI platforms as it is with carb platforms as one requires mechanical keys and the other can rely on electrical commands (PCM). So one can be tuned around this issue much easier than the other. I know I could explain this better, but it's getting late and going to bed, lol. I hope it will make some sense to someone. Oh yea, the pulsling does play a roll in all of this also, as you suggested, more later.
I agree on the hood clearance consideration being required in the design of the front inlet intakes. actually they did very well considering the design restraints.
I agree on the hood clearance consideration being required in the design of the front inlet intakes. actually they did very well considering the design restraints.
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I just sat here and read this whole post and no dyno results - DAMN. Was VH5150 right? Is that's why we have no results? I agree with s346k - you can not make a direct comparision using a cam designed for an LS1 or Fast intake. Get the valve timing right and I BET you'll have a completly different outcome.
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I just sat here and read this whole post and no dyno results - DAMN. Was VH5150 right? Is that's why we have no results? I agree with s346k - you can not make a direct comparision using a cam designed for an LS1 or Fast intake. Get the valve timing right and I BET you'll have a completly different outcome.
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I'm not a cam expert, but one thing that I do know is that most LS type manifolds utilize a cam that has a wide lobe separation angle (113-116) which works well for that manifold design, but when using an old school manifold (Victory Jr), I think your should use a cam that fits that design with a LSA of around 110-112 unless you're going FI or want to rev it to the moon. On the Victory Jr, just closing up the LSA will boost low end torque while still providing upper RPM HP. If I was to use the V. Jr, I would build it like I was building an old school SBC - as far as cam choices are concerned (if that makes any since). Now I'm not saying it will out perform the Fast, but I think it would perform a hell-of-a-lot better.
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I'm not a cam expert, but one thing that I do know is that most LS type manifolds utilize a cam that has a wide lobe separation angle (113-116) which works well for that manifold design, but when using an old school manifold (Victory Jr), I think your should use a cam that fits that design with a LSA of around 110-112 unless you're going FI or want to rev it to the moon. On the Victory Jr, just closing up the LSA will boost low end torque while still providing upper RPM HP. If I was to use the V. Jr, I would build it like I was building an old school SBC - as far as cam choices are concerned (if that makes any since). Now I'm not saying it will out perform the Fast, but I think it would perform a hell-of-a-lot better.
I think you're mostly correct. However, I believe that the wide LSAs that are rampent with the LS crowd have more to do with driveablility and emissions than performance. I think, with a decent exhaust, that the increased overlap from a tighter LSA would benefit both the victor and underplenum design equally. I guess I'm just reiterating that no cam swap is going to make the victor do something it wasn't designed to do (produce torque under 6500 rpm).