Shorter Runners for FAST Intake!!!
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Joined: Apr 2014
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Thread Starter
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Joined: Aug 2009
Posts: 1,845
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From: Coast of San Mateo County Between Pacifica & HMB
Original info from Super Chevy July 2016 I believe.
Good technical info on the Runners.
Poor Test Engine to showcase the benefits/differences IMO.
Needed aftermarket heads and or LLSR and spin to ~7500 RPM
with stock displacement, or 4.00" Stroke 416" to ~7000 RPM
To see worthwhile benefits, not just my opinion.
Good technical info on the Runners.
Poor Test Engine to showcase the benefits/differences IMO.
Needed aftermarket heads and or LLSR and spin to ~7500 RPM
with stock displacement, or 4.00" Stroke 416" to ~7000 RPM
To see worthwhile benefits, not just my opinion.
Original info from Super Chevy July 2016 I believe.
Good technical info on the Runners.
Poor Test Engine to showcase the benefits/differences IMO.
Needed aftermarket heads and or LLSR and spin to ~7500 RPM
with stock displacement, or 4.00" Stroke 416" to ~7000 RPM
To see worthwhile benefits, not just my opinion.
Good technical info on the Runners.
Poor Test Engine to showcase the benefits/differences IMO.
Needed aftermarket heads and or LLSR and spin to ~7500 RPM
with stock displacement, or 4.00" Stroke 416" to ~7000 RPM
To see worthwhile benefits, not just my opinion.
I know I can lose by running a Hi-Ram on a 5.3 Suburban but I'm not going to write an article about it. The FAST mid and short runners may not be the answer but at least use them appropriately. That article, as written, is barely worth reading.
Last edited by Mercier; May 16, 2017 at 12:39 PM.
Back in 2015 SpeedTigger posted up runner measurements of the Victor Jr L92 intake on yellowbullet.
The actual measurements go like this:
LS3/L92 Victor Junior runners with cross section measured at the plenum:
Outer cross section 3.100x1.250 with a 7.00-7.500 length
Inner cross section 3.110x1.210 with a 5.00-5.25 length
The runner length averages exactly the same as the mid length fast at 6.25".
I'm estimating actually that the runner volume on average is a bit higher with the fast intake. The plenum volume will also be larger on the fast than the single plane.
Does this mean that we should be camming these things nearly identically to what the single plane carb intakes like to see? That is going to mean much more overlap than a traditional LS3 cam which tends to be in the 10-18* overlap range for a street application...probably will want tighter centers with more like 25* overlap while trying to keep IVC in the same place or a little earlier (tough to do when adding lots of overlap).
The cam used in the comparison test no doubt was optimized for long runner EFI intakes.
The actual measurements go like this:
LS3/L92 Victor Junior runners with cross section measured at the plenum:
Outer cross section 3.100x1.250 with a 7.00-7.500 length
Inner cross section 3.110x1.210 with a 5.00-5.25 length
The runner length averages exactly the same as the mid length fast at 6.25".
I'm estimating actually that the runner volume on average is a bit higher with the fast intake. The plenum volume will also be larger on the fast than the single plane.
Does this mean that we should be camming these things nearly identically to what the single plane carb intakes like to see? That is going to mean much more overlap than a traditional LS3 cam which tends to be in the 10-18* overlap range for a street application...probably will want tighter centers with more like 25* overlap while trying to keep IVC in the same place or a little earlier (tough to do when adding lots of overlap).
The cam used in the comparison test no doubt was optimized for long runner EFI intakes.
Last edited by spanks13; May 17, 2017 at 05:24 PM.
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TECH Fanatic
Joined: Aug 2009
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From: Coast of San Mateo County Between Pacifica & HMB
before he ever installed the Fast Mid Length Runners,
unless I mixed him up with another member.
He last dynoed with the hydraulic(BTR large displacement/stroker) cam and FAST intake with mid runners. Switched to the Holley Sniper intake. I think he got interested initially because it is so much more attractive than the plastic intakes but said it runs very well too. I am sure he will get some numbers with it soon.
Yep, I sold the FAST. It worked well, but I just don't care for the design of the fast intakes with all their miles of rope gaskets sealing the runners and two halves together. Too many points for leaks. I did go with a Holley sniper low profile for the ls3. It's runner lengths are comparable to somewhere between the fast race runner and mid length runner. My first impressions of the sniper, love it. It looks bad ***, came with the fuel rails, cross over line and rail fittings for damn near 1/2 the price of plastic.
Just from driving, seems identical to how the car drove with the fast intake.
Just from driving, seems identical to how the car drove with the fast intake.
Last edited by 05CTSV; May 18, 2017 at 08:36 AM.
Joined: Mar 2007
Posts: 1,149
Likes: 60
From: Saskatchewan, Canada - where arguing "DA" is for the slow and weak...
FAST needs to come down to reality and accept that they are not the only game in town. That means a price adjustment.
I know I would have bought one over the Mid-Rise used on our TBSS if it was available at the time. The plenum volume and runner length is very favourable. I wouldn't be surprised if there is an impact on valve events to optimize these types of intakes.
FAST needs to come down to reality and accept that they are not the only game in town. That means a price adjustment.
FAST needs to come down to reality and accept that they are not the only game in town. That means a price adjustment.