This post is borderline classified ad, feel free to use the classifieds here, they're free. :thumbup:

 

yeah lets bring this post in a better direction lol pics? describe the process you used to actually create such an intake. did you use a tunnel ram thats in production and modify it or was this a ground up design? what are the specs on the engine you used as a test subject?

 

I used a Weiand base and designed custom tops for it. Attempting to attach a picture.

OK, that worked.
From the picture you can see how the plenum area is divided into four plenums.

 

So I had the idea to divide things up to get better venturi velocity at low RPM. I have a friend who is a hardcore engine builder and has a dyno. We tried a bunch of different schemes to get the fuel distribution right, and then had to do a bunch of carburetor customization to get the carbs to deal with the uneven firing in each plenum.

Tested on a bone stock Goodwrench 350, an 11:1 compression engine with ported L98 heads and a .570 lift roller cam, and the history-unknown-but-appears-to-be-stock-except-for-headers 350 in my 1971 El Camino. The torque graph is off the Goodwrench engine.

 

I used a Weiand base and designed custom tops for it. Attempting to attach a picture.

OK, that worked.
From the picture you can see how the plenum area is divided into four plenums.

Look's like two plenum to me... :mwink:

Front and back makes two..

 

Each top is completely divided in half. There are two tops, each of which has completely separated right and left plenums. So there are four plenums all together. Using small-block Chevy cyinder numbering, there is one plenum for #1 & #3, one for #2 & #4, one for #5 & #7, and one for #6 & #8.

When you start thinking about the firing order, you quickly see a big problem we had to engineer around. #5 and #7 fire right next to each other in the firing order. The other pairs have a pattern like bang-rest-rest-bang-rest-rest-rest-rest (for #1 & #3). So you get this weird induction, rest-two-cycles, induction, rest-four-cycles pattern. For some pairs the cylinder under the primary venturi goes after four rest cycles, while for the #6 & #8 pair it is the cylinder under the secondary. So we had to do some major work on the carburetors to get even fueling everywhere. We have screw-in air bleeds, and each venturi has jetting and air bleeds tuned separately. We have 8 wide-band oxygen sensors on the dyno so we can graph what each cylinder is seeing for air-fuel all the way through the pull.

 

Each top is completely divided in half. There are two tops, each of which has completely separated right and left plenums. So there are four plenums all together. Using small-block Chevy cyinder numbering, there is one plenum for #1 & #3, one for #2 & #4, one for #5 & #7, and one for #6 & #8.

When you start thinking about the firing order, you quickly see a big problem we had to engineer around. #5 and #7 fire right next to each other in the firing order. The other pairs have a pattern like bang-rest-rest-bang-rest-rest-rest-rest (for #1 & #3). So you get this weird induction, rest-two-cycles, induction, rest-four-cycles pattern. For some pairs the cylinder under the primary venturi goes after four rest cycles, while for the #6 & #8 pair it is the cylinder under the secondary. So we had to do some major work on the carburetors to get even fueling everywhere. We have screw-in air bleeds, and each venturi has jetting and air bleeds tuned separately. We have 8 wide-band oxygen sensors on the dyno so we can graph what each cylinder is seeing for air-fuel all the way through the pull.

I see them now.... :drunk: I guess I was in the sun to long today.. :sweat: :thumbup:

 

Wow keep us up to date more pics wish i had the resources to do things like that

 

spider leg manifold.

A few years ago i built a corvair engine for my dune buggy They have intregal intake as part of the head. I machined the manifold part down, added mounting flanges then welded up steel tubing like a set of headers to a box and used a 2 barrel holly truck carb. It would pull the wheels up in second gear.

 

Interesting. Looks like it is air flow limited s the torque at 5000rpm is equal. So it likely does not make any more peak horsepower than the stock manifold even thou it makes more low-mid power.

How does your manifold compare to a out of the box weiand tunnel ram?

We're not airflow limited on that engine.
Horsepower peak with the Street Ram was 286, vs. 274 with the Performer.
Where we did get into limitation is on the 350-inch 11:1 roller motor we ran. There the RPM air-gap style intake made 460HP peak vs. 440HP for our setup. We made more power everywhere below 4000RPM. So I'm thinking 450HP is about the limit of engines it makes sense to put this on.

We ran the regular Weiand top with a pair of 390CFM vacuum secondary carbs to give it the best possible chance on the mild engine. Those carbs are over $700 for a pair, so way more expensive than anything you get in the combo kits from Summit or Jegs. Our setup made 42lb-ft more torque at 1500RPM, 23lb-ft more at 2000, and keep making more up to 4000RPM where they crossed over. The regular top made more top-end power, but was mushy down low even with the small vacuum secondary carbs. If you put on the 450CFM mechanical secondary carbs you get in the kits, it would be terrible down low because the venturi velocity would be so bad.

This setup is so eager and responsive on the street. If you coudn't see the dual carbs you would swear it was a single four on a dual-plane.

 

This setup is so eager and responsive on the street. If you coudn't see the dual carbs you would swear it was a single four on a dual-plane.

that being said wouldn't it be easier and more economical to just run the single carb dual plain and save the $$???

 

Keep up the good work! Too cool!
ssmonty

 

that being said wouldn't it be easier and more economical to just run the single carb dual plain and save the $$???

For sure! But then you don't get the eye candy.
The point of this project was to build eye candy that works well on the street.

 

hehe i like shiny stuff too :welcome: :thumbup:

 

I like this. Really. Having ran the Weiand and 660's back in the day, I know it can be a bit difficult to deal with. Not impossible, but I did curse at it a few times.

If I had the jack, I'd buy the kit just to check out how it really runs on a stocker w/highway gears. Would be awesome to "faux rod" the ol' lady's dd. I can see the looks already from the other soccer moms

Cool twist on an old favorite. Good luck with this. I'd buy it. Eye candy is great when it is also useable, especially on an actual street car.

 

Why not divide it into "8 plenums" and just use it with carbs that have equal venturis and a mechanical linkage (along with 2 accelerator pumps and 4 corner idle etc). Essentially you would create an IR system from 2 4bbl holleys, which could REALLY make an improvement down low. Tuning would be easier than it is right now as well since you could tune each cylinder individually and there wouldn't be an uneven mix of cylinder pairings.

you could also try altering your cam timing on each lobe to compensate for the firing order, but that would take more R&D and $$$ than I think you would want to invest for a street application.

 

I started out intending to do an IR system, but you have some problems there. One is that you basically need the same CFM capacity to feed one cylinder as two. That is non-intuitive, but it is how the Weber IR systems work. Each throat is set up at about 300CFM for an independent runner V8. That means you need Dominators to get the airflow you need. With the pairing-up business, I can use much less expensive carburetors and still have the capacity to feed the cylinders. Plus I get progressive throttle - one lower-capacity venturi is open at part-throttle, so it gets better velocity. The second venturi is not open until the engine can use the extra airflow, so it does not kill the velocity.

With 660 center squirters, each cylinder would only be connected to a venturi capable of flowing 165CFM. That is definitely not enough. Also, even the 660s open the primaries some distance before opening the secondaries. That can be fixed with custom linkage, but the airflow problem cannot.

There actually were Dominators made for IR systems in the '70s. Grumpy Jenkins ran them, but could not get the top end power he wanted. The carbs are no longer available. IR Weber setups also are known to limit the top end to around 550HP even with their biggest setup. IR systems do make good bottom end, but the larger-throat setups do kill some of it off due to low velocity through the one big venturi at low RPM.

 

Each throat is set up at about 300CFM for an independent runner V8. That means you need Dominators to get the airflow you need.

If EACH runner gets 300 cfm, you'd need two 1200 cfm carbs!

What Weber has 600 cfm flow? The approximate total cfm for different IDF carbs:

40mm= 212 CFM

44mm =290 CFM

48mm = 340 CFM

Even if each throat is set up at about 150 cfm for an independent runner, that is still 1200 cfm total. But you'll have a hard time convincing me you need 2400 cfm combined.

 

Not so on the Weber CFM. Weber 48's are 350 or so CFM _per_venturi_. You can read all about this on GT40s.com, where they build Weber IR motors that run out of breath around 500-550HP with 48 IDAs.

That thing you said about needing 2 1200 CFM carbs is precisely what I was driving at when I said I needed two Dominators. Like I said, it is quite non-intuitive, since you can feed a 500HP engine with a 750 Holley on a single plane. That's because the cylinders share the airflow through the venturis. Once you start dividing things up, you need to keep a certain capacity visible to each cylinder.

 

Anyone tried these things on yet?
Seen the site, price moves around a bit (trying to find the price point?)

Still no pics or vids of these parts at work on a car? Wondering if it generated much interest.

L79, you still workin on this design or any other creative stuff?

 

Hoping to get pics and video of the El Camino this weekend. A customer with a '63 Corvette is sending a picture too.

We've also got some more experiments to come that will trade off some bottom end to gain some top end.

 

Anyone have any news or info on this? I see that there is a website that references "out of stock" for the products and wonder if anyone on here has any experiences with this set up??

I am interested in buying the tops and carbs to go onto my Weiand Tunnel Ram, but want more information prior to committing to the $$$.

 

Well, I sprung for the $$$ and I am not all all disappointed. I opted for the tops and carbs only since i already had the tunnel installed. I had been running the weiand tunnel for about 2 years and was never happy until now. This set up is the cats meow (I really wanted to say the "cats ***" but didn't know if that was acceptable). Did I say that out loud?

Anyway, back to the results. I can now stand on the throttle from a standstill and have heart stopping response. There is absolutely no hesitation or stumble at any speed.

I had only two concerns. The first is that the new plenums get icy cold and depending upon the humidity, they sweat. I am pretty happy that the charge is so cold though.

The second and only other topic is, that I could not get a steady vacuum reading when trying to read each carb separately from the base vacuum port. The needle was briskly fluctuating back and forth with a 10 hg swing. Then I thought to tee the two ports together and then got a steady reading that I could set the idle mixture with.

At this point, I am thrilled with the set up, and as a side note, whenever I had a question or concern, Wayne was extremely responsive. So much so that he responded to an email of mine over the weekend within 10 minutes.

If any of you are considering this, I highly recommend it and would be happy to discuss my experience with you.

Steve

 

i would like more information on this mainly for my own education ut also bc im starting a job building and machining engines and the employer would be interested in something like this

 

i would like more information on this mainly for my own education ut also bc im starting a job building and machining engines and the employer would be interested in something like this

More information on the patent pending design here:

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