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 Post subject: Intake Runner Length
PostPosted: Wed Apr 03, 2013 2:41 pm 
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TBI Slant 6
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Location: Lincoln, NE
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I recall a particular book being referenced for intake runner design, but can't find the name. Anyone?

Also, I'm a little curious how the formulas compare to the commonplace V8 practice of grabbing single-plane intakes (Victor Jr, M-1, Dominator) and converting them to EFI. Seems like people are getting really fantastic results regardless of the calculations.

Thanks!

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 Post subject: Vizard...
PostPosted: Wed Apr 03, 2013 3:33 pm 
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Quote:
I recall a particular book being referenced for intake runner design, but can't find the name. Anyone?


I know that David Vizard's How to make Horsepower Vol.2 has the formula to compute the length based on various reflections, etc...Also has some tuning and intake throat cross sections to consider.

After using his formula last week (and after his explanation that the ideal length may be too long depending on the engine), the slant six on a 2nd or 3rd reflection at high rpm, dialed in at a 43" long intake runner.. once you are up to the next set it dials down pretty fast to 23-24" runner.

Would be nice if there was another book around that was as easy to understand as that one.

-D.Idiot


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 Post subject:
PostPosted: Wed Apr 03, 2013 4:36 pm 
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I just wonder how much it matters...the runners on Edelbrock's ram-style TPI set-up can't be longer than 12" and people are making crazy horsepower on those...

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 Post subject: I'll let...
PostPosted: Wed Apr 03, 2013 4:56 pm 
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I'll let others chime in, but the book does cover tuning the inlet as well as the intake runner length, so there's more going on there than just the intake runner length...the book also explains that if you tune it for a certain reflective wave the runner can be much shorter...there are many other dynamics to consider in this.

FYI.

-D.Idiot


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 Post subject:
PostPosted: Thu Apr 04, 2013 11:04 am 
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Turbo Slant 6

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You have to stop & consider what the engineer was trying to accomplish with any given intake design. Think of the original TPI Chevy's or the Chrysler "long-ram" big blocks. Both were trying to maximize TORQUE in a specific rpm range (about 2500-3500 or so) in a production engine. Above that they "ran out of breath", the same design that improved low speed oper now hindered hi rpm.

High HP engines "carry" torque into hi rpm's- they need less "restrictive" intakes to get there. EFI, good cyl ports, cam designs, & V8 cubic inches let them produce lots of torque down "low". You could make apply "inertial supercharging" to intake design for one of these V-8's & make more torque at your "tuned" rpm- at the expense of other rpm ranges (face it, HP numbers sell parts more than torque)

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 Post subject:
PostPosted: Thu Apr 04, 2013 12:26 pm 
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Several "newer" model engines have dual length intake runners controled by a valve. The Ford SHO comes to mind.

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 Post subject:
PostPosted: Fri Apr 05, 2013 5:04 pm 
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TBI Slant 6
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Alright, I've got Vizard's Horsepower Vol. 2 coming...Barnes and Nobles has it for $29 new. Amazon is just crazy...

While I was there, I found Corky Bell's book and couldn't resist buying Vizard's Porting book as well.

Kinda spendy trip, but definitely worthwhile. Wish I had done this over the winter.

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 Post subject: Yep...
PostPosted: Fri Apr 05, 2013 5:59 pm 
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Quote:
Several "newer" model engines have dual length intake runners controled by a valve. The Ford SHO comes to mind.


Charlie that is the best example on this side of the pond and the Ford Taurus SHO was used as an example in Ben Watson's "How to Build and Modify Intake and Exhaust systems" (which is a good 'intro' book for the novice in understanding the basic things, but time has marched on and other authors have much better information). There used to be a few jaguar mills in the last decade that used the same principle as well.

-D.Idiot


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 Post subject:
PostPosted: Sat Apr 06, 2013 5:03 am 
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I haven't read any of the books on intake/exhaust tuning in many, many years. Back in the '60's I found a book that had a ton of info, and formulas. I buildt a Ford flathead circle track engine, using the info. The rules stated "maximum two barrels of carburation allowed" (flathead V-8 and inline engines only, that allowed the ford and chevy sixes to add a barrel). I built a "tuned" intake out of tubing, and used two large 1 bbl carbs from a truck (I think international). It met the "letter" of the rules, and nobody complained, as my car wouldn't go around a corner if it was on railroad tracks. We put the motor in a good handling car, and you should have heard all the protesting. It would pull off the corner better then any other car there.

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 Post subject:
PostPosted: Sun Apr 07, 2013 6:49 pm 
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I use an Offy Dual Port on my van. I wanted torque for a 6000lb truck.

I haven't seen the SHO. I have seen the small 4 bangers with 2 different sized runners.

BTW I have a friend that runs in the 12's with a 470 low deck stroker with the long rams. It's a '60 4 door Fury. IIRC he is running 3:55's.

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 Post subject:
PostPosted: Tue Aug 20, 2013 2:34 pm 
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Check out the ramchargers formula for intake length. They did alot of work with the long ram intake and you generally tune to the cam events and rpm, i think my stock slant runners spec,d out at around 7.25 inches plus the length of the head ports. This was a 3rd wave setup, or whatever they used for the short runners.


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 Post subject:
PostPosted: Tue Aug 20, 2013 10:52 pm 
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3rd wave?

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto :-( Dually Clubcab needs a injector pump
2005 Golden Couch Buick


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 Post subject: Yep...
PostPosted: Wed Aug 21, 2013 7:26 am 
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Quote:
3rd wave?


Within the intake there is a wave that bounces between the port and the end of the plenum, depending on the length of the runner the wave may become beneficial (ram tuning), but will not be every wave or every other wave, but may be the 3rd or 4th reflection....Using the formula for calculating intake runner length in Vizard's 2nd book on tuning intakes, the standard 225 at race rpms, would need an intake runner length of almost 6' to take advantage of the 1st wave reflection, 2nd wave reflection is closer to 4-5' long, 3rd wave about 3-4', and 4th wave matches the clifford hyperpak intake...

-D.Idiot


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 Post subject:
PostPosted: Fri Aug 23, 2013 8:52 pm 
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EFI Slant 6
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Car Model: 1965 Barracuda 'S' auto
Yes, it must have been the 4th wave. Its all about the intake duration in degrees. Chrysler made 2 intakes for the long ram, a long one and a shorter one for the higher RPM running cam.


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 Post subject: Re: I'll let...
PostPosted: Tue Jun 04, 2019 2:38 pm 
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2 BBL ''SuperSix''

Joined: Sun Sep 23, 2018 3:03 pm
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Car Model: 1962 plymouth valiant
YOU WANT EFFICIENCY/POWER/92 OCTANE MACHINES......

WRAP THE INTAKE WITH THE EXHAUST MANIFOLDS WITH

DOUBLE-STRENGTH ALCOA SO IT IS WIND-TIGHT AND

SPRAY POLYUREA FOAM INSULATION TO HOLD THE HEAT.

SMOKEY UNICK USED A HEAT CHAMBER ON HIS RIGS AND

WRUNG OUT INCREDIBLE MPG's WITH HIS INNOVATIONS !!

WAKE UP......


-P-


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