My tuned length is 13.5" from the valve to the manifold intake port radius. I tuned for a 380 cid engine making best power at 7500 rpm under boost.

Tom V

 

Tom,

Could you expand on your comment "You need 4 times the airflow with a Individual Runner intake vs a typical dual plane intake as that runner has to supply all of the air to the engine from one carb throat/throttle blade." Some of it seems logical, one cyl is grabbing air from the dual plane while the other is in a different stroke so it shares a volume. Does the 4x number come from the number of additional cyls within the same plane?

Also, I've seen dozens of ways to calculate runner length for a given application, all of them really similar. How do you do it and why? I'm using all of the info on this thread and the other we have discussing intake design for a Buick GN. Thanks in advance!

Tommy

 

Correct. A single plane intake does well on the high rpm engine because the typical carb can handle the pulses of the 8 cylinders in an almost continuous flow operation. No starting and stopping of the booster signals. The Individual Runner intake with one carb bore to each runner sits around for a period of time and then demands a massive amount of air and fuel in a very short period of time. Therefore you need a LARGE throttle blade/runner area.

I worked with some people at Holley on a dual quad SB Engine that used IR technology and special dual dominator carbs with 2.75" Throttle blades per barrel. About 4800 cfm available on this SB Chevy but not runner saw more than 600 cfm at any one time. Engine STARTED to get happy about 4500 rpm and would rev to over 10,000 rpm for best power. A massive cloud of fuel hung over the carbs below 4500 rpm. A engineer named Zora Duntov was the consultant on the project.

I use the back of the valve to the carb booster for my calculations. Some use back of valve to inlet air horn on mechanical efi stuff. Lots of different opinions.
On the efi intake in this thread it was "back of valve to inlet air horn". I assume that the plenum is like a large room with an efi engine in it running mechanical injection. The plenum (even with a single throttle body should be able to support the flow of each individual runner pulse (like a row of steel ball bearings (or freight cars) on a track.

Tom Vaught

 

You... you... you knew Zora Duntov?!?!

 

I have a feeling Tom V. knew everybody of influence

 

Zora was also the guy behind the old Holley "Z" intake divided manifold with the communication passage between two runners.

http://www.trifive.com/forums/showthread.php?t=18517

"I know Holley paid Zora Arkus Duntov of chevrolet good money to design these intakes..the box even had his picture on it but these were marketed as gas saving intakes...great as long as I can get good power out of it too."

Zora was a nice man, he was gone from Chevrolet by then and on contract to Holley.

I have been fortunate to have worked with a lot of the old heroes of the day. Smokey Yunick did some of the first twin turbo work on a Traditional Pontiac Engine.
At one time I had all of those parts. A Big money collector of Super Duty Pontiac parts talked my out of them and then he died of cancer. The stuff is stashed away somewhere.
Smokey was a very interesting person if you got to know him and he liked you.

Tom Vaught

 

Wow! That's pretty interesting. Between you and the people you knew, I'm sure there are lots of good stories to be told. HAHA

 

That needs a pair of QJets, maybe three. ..... wouldn't it be nice if you could just put it on that engine Arnie .... err, borrowed....

 

Always like Tuner's Humor and his Knowledge on carburetors. Don't think those 3 q-jets would like the amount of boost I want to run on this thing.

Tom V.

 

I really enjoyed our phone conversation when we spoke years ago as you were starting this forum. You're a class act with a big heart, and an amazing resource for this forum. The intake looks wonderful, and I wish you the best in your build.

Chris

 

Thanks for the nice reply, Chris, and the compliment on the intake.

Tom V.

 

You're the guy who introduced me to blow-through QJets on Pontiacs.

http://www.wallaceracing.com/TFReviveWhat.html

http://www.hotrod.com/how-to/engine/ccrp-0912-turbo-pontiac-400-build/

I figured if you use three you can have three times the boost. Besides, QJets are so easy to calibrate it will save you a lot of time fiddling around with programming some stubborn ECU and all that nonsense. Everybody knows a QJet is the epitome of The KISS Principle in fuel metering.

Will there be a second set of injectors above the runner inlets?

 

I actually tried that deal (firing across the plenum on a 2885 HP Twin Turbo Pontiac Engine with a custom 5" diameter round tube plenum
(and a front inlet Throttle Body like I will have with the intake in the thread. It did not work worth crap. Travis Quillen and Rod Butler are the owners of the car.

I have attached some pictures of the engine. Before and After. The third picture with the Turbos feeding directly to the rear of the plenum was done when the
engine was converted to methanol fuel. The engine had 20 Injectors. Can you find the other 4 injectors?

Tom V.

ps These are the same guys who helped built "The Crow's" Pontiac engine on Street Outlaws (both inter-cooler and now on methanol.)

The Pontiac is now dressed up like a White Judge on the show. The engine pictures shown are for the 63 Tempest Race car that Travis and Rod race. (6.27 @ 228 mph)

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I should have posted WHY the intake did not work well.

1) The Injectors "nozzles" were on one side of the 5" tube Plenum and the Runner Inlet for that injector was on the other side of the 5" tube Plenum.

At high boost conditions the velocity of the charge air going into the plenum was high enough to push the fuel rearward of the actual injector spray
pattern desired (center of the runner opening). So the fuel migrated more to the rear cylinders than to the front cylinders.

This meant that the rear cylinders were fuel rich and the front cylinders were fuel lean.

So you had to calibrate to offset that deal vs having all of the runners make about the same power with the fuel injected properly to the runner.

So why did we have the other 4 injectors? Anyone know?

Tom V.

 

I was thinking along the line of the injectors over the trumpets in this Renault F1 engine on the dyno. As the video plays there are occasional views of the injectors spraying. Interesting the response to the RPM and load changes. It sounds like a simulated race lap.



You dog, you and Zora were doing this stuff more than thirty five (35) years ago when I was still carving jets and metering rods out of obsidian for carburetors made from hollowed out logs. Life was hard out here in The Wilderness. I get to fix a '53 Olds Rochester 4 Jet tomorrow, well, today now.

The 4 injectors are in the pipe at the junction of the two small pipes, one from each turbo, to the large single pipe to the throttle body. My guess is to cool the charge so you can freeze up the throttle with ice, like Kevin Cogan's problem at the start of the '82 Indy 500. Uh - Err ... I meant to get more fuel in the front of the intake to address the distribution issue?

(I can't find the soft sarcasm sticky ;-)

 

Well, like Tuner said, they are on the large up pipe after the compressor discharges are brought together.

I imagine that was to increase the residence time to allow for sufficient vaporization/evaporation to cool the charge since your residence time from the injector to the intake valve would be very short at high RPM.

But I can't see them on the new layout, I imagine that was because the methanol did enough cooling for them in a typical injector arrangement?

 

Two things happened on the turbo set-up.

Agree that when the team went with methanol the cooling effect was much better vs gasoline.

The injector sizes offered grew massively vs the old 160# Bosch injectors used at the time.

But as I said before the 5" tube was a long distance for the fuel to travel to get to the runner vs the
Renault F1 engine's assumed distance to the bellmouth on the dyno in the video.

Tom V.

 

Do you have room to put injectors in the lid directly over the runner entrances to spray directly down the runners, similar to the images in the F1 engine video? In that version of the F1 engine the injectors are inside the plenum or air box, whatever you would call it, not sure where the throttles are or how many are used in that engine. I assume you are using a throttle body at the plenum entrance like the engine in the attached pictures above.

 

<----Interested in "At Cost" turbos

 

Tuner, the 2885 HP deal was many years ago and since then they have gone very quick with their second design injector position, so I am keeping out of that discussion.

Right now they are taking about 500 HP out of the tune-up to get it down the track. Think they are good for power for a while.

Tom V.

PS the Owner of the site frowns on selling parts on his website using threads. Hint! Hint!