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Whats better for fuel injection- long runners for torque or large runner crossection for flow?
https://slantsix.org/forum/viewtopic.php?t=65104		 Page 1 of 2
Author:  Reed [ Mon Jul 13, 2020 3:20 pm ]
Post subject:  Whats better for fuel injection- long runners for torque or large runner crossection for flow?
Long term planning for a fuel injected 225 build for my truck. I am eventually possibly adding a turbo. I have stock cast iron single barrel, stock cast iron two barrel, stock aluminium single barrel, and an Offy aluminium four barrel intake to play with. I have been kicking around the idea of eventually running either a hyperpak or a Clifford intake. The hyperpak because EFI cures all the wet intake problems and the long runners improve torque (and it just looks cool). But the Clifford has bigger runners for more flow and some already have pads for injectors cast into the runners (saves a bit on machining and fabrication costs :lol: ). EFI does not require intake heat, so I will be running dual Dutra Duals. No need to connect to the stock exhaust tower.

The truck will have 3.9 rear gears and an overdrive trans, so I will have the option of spinning the motor up into RPMs above the usual 2500-3000 RPM limit.

For a fuel injected and possibly turbocharged truck motor, would it be more beneficial to have the long runner hyperpak or the fat runner Clifford?

I would appreciate input from people who have experience with carbs and fuel injection on the aftermarket intakes. If this is too big of a topic, pointing me towards a book or website with this kind of info would also be appreciated. Thanks.
Author:  ProCycle [ Mon Jul 13, 2020 3:42 pm ]
Post subject:  Re: Whats better for fuel injection- long runners for torque or large runner crossection for flow?
I believe if you go turbo the shape of the runners matters MUCH less than running naturally aspirated.
So, if it really will be turbocharged pick the manifold that will make the fabrication and installation easier and tidier.
Author:  Reed [ Mon Jul 13, 2020 4:31 pm ]
Post subject:  Re: Whats better for fuel injection- long runners for torque or large runner crossection for flow?
That makes sense. Further, if the intake is dry due to port injection, and especially if it is forced induction, all the old principles of sonic tuning, ram effect, and fuel distribution just don't matter. In that sense, the Clifford with the cast in injectors bungs would probably be easiest. Hmm. Thanks for being a sounding board.
Author:  sixinthehead [ Mon Jul 13, 2020 5:26 pm ]
Post subject:  Re: Whats better for fuel injection- long runners for torque or large runner crossection for flow?
Forced induction pretty much throws all that out the window, but for N/A everything still applies except for fuel distribution.
Modern cars often use long runners or dual path intakes to tune the charge.
They can curl them around for packaging since they are dry so it's easy to miss how long the runners actually are.
Author:  Joshie225 [ Mon Jul 13, 2020 6:13 pm ]
Post subject:  Re: Whats better for fuel injection- long runners for torque or large runner crossection for flow?
Quote:
That makes sense. Further, if the intake is dry due to port injection, and especially if it is forced induction, all the old principles of sonic tuning, ram effect, and fuel distribution just don't matter. In that sense, the Clifford with the cast in injectors bungs would probably be easiest. Hmm. Thanks for being a sounding board.
The ram effect is still there as is the pressure wave tuning. If you build a good normally aspirated engine it will be a better boosted engine. Say you have a 150 hp engine and you feed it 15 psi of intercooled boost. Assuming no detonation or other mistakes you'll end up making 300 hp. But if you start with a 200 hp engine and do the same thing you'll end up with 400 hp. If the Hyper-Pak intake provides a torque boost in the RPM range you want then that's a good choice and you'll make more power in that RPM range with the same manifold pressure and timing. It's pretty easy to overcome mediocre performance with more boost, but if you don't have a good flowing cylinder head or manifold or exhaust you'll always make less power than you could have at a given fuel octane and detonation limit.

Check out Richard Holdener on YouTube and see some of the crazy stuff he's built and tested. Here's an intake manifold video to get you started. https://www.youtube.com/watch?v=Eh4P8lvBuCU&t=619s
Author:  Reed [ Mon Jul 13, 2020 6:57 pm ]
Post subject:  Re: Whats better for fuel injection- long runners for torque or large runner crossection for flow?
Thanks! I will start watching videos. Time to start doing homework. And install a tach in the truck. 8)
Author:  SlantSixDan [ Mon Jul 13, 2020 7:58 pm ]
Post subject:  Re: Whats better for fuel injection- long runners for torque or large runner crossection for flow?
Quote:
if the intake is dry due to port injection, and especially if it is forced induction, all the old principles of sonic tuning, ram effect, and fuel distribution just don't matter.
I don't agree. Fuel distribution, no, you needn't fret about that, but ram effect and sonic tuning are airflow matters, and they apply whether or not that air is carrying atomised fuel.

Those factors are less relevant with forced induction, tho.
Author:  Reed [ Mon Jul 13, 2020 9:55 pm ]
Post subject:  Re: Whats better for fuel injection- long runners for torque or large runner crossection for flow?
See? This is why I like posting on this site. I get good info from people who know more than me, and they point me to sources where I can educate myself. Thanks!
Author:  Dart270 [ Tue Jul 14, 2020 4:23 am ]
Post subject:  Re: Whats better for fuel injection- long runners for torque or large runner crossection for flow?
I agree with most of the statements above. Nice discussion. If you can fit it easily, I would go Hyperpak. You will likely get faster spool up and more low end, and it will just look so damn cool...

Lou
Author:  Reed [ Tue Jul 14, 2020 9:45 am ]
Post subject:  Re: Whats better for fuel injection- long runners for torque or large runner crossection for flow?
I am working with a D series truck engine bay, just about the biggest and widest open engine bay I can think of. I definitely have room for a hyperpak. Hmmm. I need to do more homework.
Author:  DadTruck [ Wed Jul 15, 2020 8:35 am ]
Post subject:  Re: Whats better for fuel injection- long runners for torque or large runner crossection for flow?
I have to agree with Dan on this one, as boost comes in to play the advantage of wave tuning diminishes. What does help boosted motors is cooling the pressurized air charge. So with boost, if you have room to increase the length of the piping from the turbo to the intake port, add a charge air cooler to the stream.
Author:  Reed [ Wed Jul 15, 2020 9:01 am ]
Post subject:  Re: Whats better for fuel injection- long runners for torque or large runner crossection for flow?
Thanks. I can see I have lots of learning to do. An air to air intercooler can probably be made to fit, so long as I still have room to add an AC condenser.
Author:  Charrlie_S [ Wed Jul 15, 2020 2:27 pm ]
Post subject:  Re: Whats better for fuel injection- long runners for torque or large runner crossection for flow?
Quote:
Thanks. I can see I have lots of learning to do. An air to air intercooler can probably be made to fit, so long as I still have room to add an AC condenser.
How about a water to air charge cooler, and use the AC to cool the water? :wink: :wink:
It has been done before
Author:  Reed [ Wed Jul 15, 2020 3:07 pm ]
Post subject:  Re: Whats better for fuel injection- long runners for torque or large runner crossection for flow?
Quote:
Quote:
Thanks. I can see I have lots of learning to do. An air to air intercooler can probably be made to fit, so long as I still have room to add an AC condenser.
How about a water to air charge cooler, and use the AC to cool the water? :wink: :wink:
It has been done before
Sounds "cool" (ha) and effective, but that is too much plumbing work and thinking for me. I just got done rebuilding the AC system on my 1990 Ramchager and converting it from freon to R134A. That went OK. My 76 D100 that were are talking about in this thread will be getting an old knee-knocker underdash AC unit (the one I talked to you about last year when I was going to put it in the 82 Ramchager I sold earlier this year), and I think it would be too complex for me to incorporate the AC system into the charge cooler. My fabrication skills are pretty rudimentary.
Author:  kesteb [ Wed Jul 15, 2020 9:23 pm ]
Post subject:  Re: Whats better for fuel injection- long runners for torque or large runner crossection for flow?
The "theturboforums.com" has forum for intake manifolds. Its moderator is a former ford engineer that designed the intake for the '80s 5.0 and has tested other manufacturers systems. A very good read. The "victory library" ran by "panic" also has a good section on intake manifolds, geared mostly towards carburetors. Don Dolmtech, mostly noted for big blocks, has a series of articles on his "senior dragster" on "the hamb", they include a couple of intake manifold builds.

Both Don's and " panic" theory's on the 225 were not well received here.
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