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BBC tunnel ram

General engine tech -- Drag Racing to Circle Track

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prairiehotrodder
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BBC tunnel ram

Post by prairiehotrodder »

have you dyno tested the Edelbrock #7085 tunnel ram against any other tunnel rams ? I'm using the old Weiand #1985 rectangle port and i read somewhere that Edelbrock claims their new version (made in 2013) #7085 is worth 40 - 50 hp over other t-rams (didn't say which ones). This is all pretty vague so i thought i'd ask the speed talk world. One thing i don't like about the 7085 is it only has a top for dominators. I'm liking my 4150 base 750 carbs even though i would like to try bigger carbs. Maybe 850 or 950 but not ready to make the jump to dominators. I'd have to use adapters or build my own top to run 4150 carbs on the 7085 edelbrock.
Brian

Edit : they claim it made 47 hp over the old victor 2-R and 10 hp over the competition. So i guess it depends which "competition" intakes they were talking about.
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SchmidtMotorWorks
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Re: BBC tunnel ram

Post by SchmidtMotorWorks »

It depends on your application.
Take a look at the Profiler manifold.
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F-BIRD'88
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Re: BBC tunnel ram

Post by F-BIRD'88 »

If you think that your carbs are too small try adding plenum volume and carb height.
( carb spacers) You could also build your own custom plenum for your current Weiand tunnel ram.
F-BIRD'88
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Re: BBC tunnel ram

Post by F-BIRD'88 »

Joe Sherman was a expert at this stuff.. With the big full race tunnel rams he really spin the engines up high to get the power gain. Not sure you want to go there. Takes top parts and maintenance to go there.
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WeingartnerRacing
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Re: BBC tunnel ram

Post by WeingartnerRacing »

I used one on my 565bbc it made 1118hp@7500rpm
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Eric Weingartner
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Re: BBC tunnel ram

Post by Old School »

WeingartnerRacing wrote: Tue Oct 29, 2019 11:49 pm I used one on my 565bbc it made 1118hp@7500rpm
Do you have any et -mph on the on the car with the 565? Very nice engine.
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Re: BBC tunnel ram

Post by WeingartnerRacing »

Old School wrote: Wed Oct 30, 2019 10:01 am
WeingartnerRacing wrote: Tue Oct 29, 2019 11:49 pm I used one on my 565bbc it made 1118hp@7500rpm
Do you have any et -mph on the on the car with the 565? Very nice engine.
Not yet still finishing it. Driveshaft should be here today. Hopefully in March.
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Re: BBC tunnel ram

Post by Old School »

WeingartnerRacing wrote: Wed Oct 30, 2019 10:06 am
Old School wrote: Wed Oct 30, 2019 10:01 am
WeingartnerRacing wrote: Tue Oct 29, 2019 11:49 pm I used one on my 565bbc it made 1118hp@7500rpm
Do you have any et -mph on the on the car with the 565? Very nice engine.
Not yet still finishing it. Driveshaft should be here today. Hopefully in March.
Thanks
engineguyBill
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Re: BBC tunnel ram

Post by engineguyBill »

As far as cast tunnel rams are concerned, I have had excellent results with the Dart product.
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prairiehotrodder
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Re: BBC tunnel ram

Post by prairiehotrodder »

all other things being equal, what does adding plenum volume to the intake manifold do for an engine ?

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F-BIRD'88
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Re: BBC tunnel ram

Post by F-BIRD'88 »

A larger plenum will slow the air draw speed on each carb venturi. It will tend to dampen induction pulse force both coming and going . Each cylinders intake port has a larger volume of air/fuel to draw from on each intake stroke.

sort of like the action of a shock absorber dampening a spring. Sort of like a condenser's effect action on a AC electrical circuit.

The engine can breathe deeper at high rpm if the carbs are on the small side relative to cid- power demand.

A wider plenum cross section has a slightly diffrrent effect
than a taller plenum cross section does. (Carb height above runner entries.)

Plan on carb re jetting (most likely bigger main jets if plenum volume is added.
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