By having the dual plenums you may be getting into a situation where you have lost a lot of air speed and the air mass is not bouncing off the roof and providing even distribution.

Can you just hook up a elbow to your belmouth and provide pressure to the upper plenum that way and see if thing get better for you with the distribution?

I was not sure about your design when originally posted but this may be a chance to see how good the mahovitz design with the throttle body/elbow/center feed tube bouncing off the roof works with your deal. I have tested manifold designs (we came up with at work) that were within 2% cylinder to cylinder.

Tom V.

 

ok, I will do just that. I will post tomorrow with results. Thanks T

 

I just went test it with just the 4" tube.... pretty much the same thing. I even added 1.5" of top plenum to see if it changed but no go. My next change might be using the long slot down the bottom of the top plenum to connect the two plenums instead of the radius or 4" tube. If i want an intake the works as well as Mahovitz, i'll have to call Hogan, lol! I'll update more tomorrow. Thanks! T

 

ok, it hit me today that I might not be testing correctly or my blower is not large enough to test all ports at one time.... I was testing with all intake ports open. If I am supposed to test one port at a time, my numbers are in the ballpark. I continued testing all ports at the same time. My buddy recommended that I partially restrict the port to cause a little restriction. Now all ports are restricted the same amount and the flow numbers from each ports are much closer. Tom, which way am I supposed to test? Thanks! T

 

The bench we used to look for uniform distribution read all of the cylinders at the same time.

There was a flow orifice in each cylinder 1/2 down the bore. We read the air flow fed into the throttle body and thru each orifice at the same time and read the distribution on manometers on the flow bench.

No picture attached. Picture was too large to post.
So you really need to see where the air is going when the plenum receives the air and not test one runner (which just says the runners are flowing the same when tested one at a time (a good porting job)).


Tom V.

 

ok that is cool. Thanks!

 

This is a very informative thread! I am in the process of designing my own intake also. Tom V, you mentioned that you have had success with a few different designs that worked. I would be interested in hearing about those and seeing pictures. I have tried several cardboard designs with low pressure air and don't have a design yet that I want to invest money in on a real prototype. I have been trying a single plenum on top of my current "spider" 4500 single intake. I am not real fond of the looks of those anyway. I am currently focused on a tunnel ram platform with a dual plenum top with twin Lehmann slot primaries. Any advice or thoughts would be welcome. Thanks, Chris

 

Excellent, excellent thread.

 

http://www.performanceforums.com/fo...Audi-s-Grp-B-intake-manifold-idea-good-or-bad

Someone mentioned trying to use a "slotted intake manifold" like the Audi unit. Look at post #18 in the thread above. CFD simulation.

The CFD stuff did not look good at all. (see above) and ACTUAL TESTING over hundreds of hours on the dyno confirmed the cfm simulation was spot on and the cylinder distribution was not even with the slot. The slot did nothing.

Different slot configurations were tried with very little change to the basic uneven distribution.

Tom V.

 

Similar to the results I found with my cardboard test piece. I had thought about two one facing in one direction and the other facing the opposite direction so the high pressure area would even itself out in the plenum. The other thing I was considering was to have two 3" intake ports facing each other in a common plenum. The third idea I had is similar to post number 20 in that thread, or possibly do a cross ram intake and have totally separate plenums for each bank of runners (like 2 four cylinder engines) with the plenums looking like post #20 but separated. Thoughts?

 

It is possible to do the split plenum deal (cross-ram) with the only potential issue being the engine will think it is two 4 cylinder engines and the firing order will not be even and smooth.

Post up some additional thoughts on the project.

Tom V.

 

I thought about using one of these intake bases. One is the Lower super ram gm put on the crate 502 motors very small straight up runners. Part number 12464482. It is for a oval port head but I may be able to make it work with my AFR rectangle port heads.

The other intake was used as a marine application on all the efi BBC boat engines. Casting number 12550669. It is a rectangle port intake but has really long 11" cross ram runners, but I could cut them down.

My third option is using a tunnel ram made by Dart, Pro-filer or Edelbrock. These will be very tall options.

My last and most expensive option is a custom billet intake made to my specifications.

 

hey tom v, a positive update for you.... I borrowed a buddy's gas lawn blower (commercial sized) and it put much more pressure/volume through the intake and my distribution numbers were within 2% - 3% and my worst port being 5%. I noticed the more pressure/volume we ran into this intake, the better the distribution. I will call this a victory and finish welding her up! Thanks a ton for the great info and a super informative thread! Thanks Tom V! Tracy

 

That's great news T! Makes me wonder if all my testing with low volume air and cardboard plenums was a waste of time? One of my concerns with the design that you did was the heat box under the intake. Is there a plan to address that or are you not concerned about it? Maybe you could weld in another plate so there is an air gap?

 

Hey TT, I felt like I was chasing my tail with using low volume..... As soon as I cranked up the big volume blower, it all fell in line like tom v said. I did build a heat/oil shield out of aluminum that bolts to the lifter valley floor (raised stands on a Dart Big M block) and basically runs from the bottom of the lifter valley (above the lifters and pushrods) to the bottom of the intake ports. It should keep hot oil off of the bottom of the intake. Thanks TT

 

Glad that things came around for you.

John Mahovitz, who i have known since the old Super Street days in 1998, is a very smart guy and he would not use something on his engine,
(5 second quarter mile times), if it did not work.

I tried to post a picture of our rig I designed for my company (and very skilled fabricators, welders, and electricians put together) but the file was too big.

That rig used 12 Super Flow 600 type vacuum motors (using exhaust mode design) and we could turn on 4 motors, 8 motors, or all 12 motors for our testing. Basically 1400 cfm capability, but if we had too much airflow we used a by-pass valve circuit to trim the airflow to what we needed and read the air flow with two mass air meters. A large air meter reading what went into the intake and a smaller air meter reading how much we were bypassing away from the intake manifold.

Always knew the exact air flow that way. Both air meters were calibrated on our Mass Air Meter Calibration Flow Test Stand.

Glad your plan came together.

Tom V.

 

Wow, pretty crazy how much power it takes to do it the right way. I'll continue following this thread for more ideas and thanks again Tom V for sharing your knowledge! Tracy

 

You are welcome! Really enjoy the board and the Boost Guys working on their projects.

At the end of this year I will have 40 years working on boosting projects (starting in 1976) with some draw thru Turbo Buick work I did for the first OEM company I worked with.

In 1978 I went to work for my present company, doing Boosting work on the 1979 Turbo Mustang. Been doing the work on other projects: I-4, I-6, V-6, V-8, V-10, and even V-12 engines ever since. ALWAYS LEARNING NEW STUFF EVERY DAY. The 1979 engine made 140 horsepower from a 2.3L engine. A 1996 "Brand X" engine program I helped with on parts and knowledge made just under 3000 horsepower. The HP game has stepped up a lot over the years vs the old 396-375 advertised horsepower days in the 60s.

Tom Vaught

 

Awesome thread, thanks! Ive considered doing similarly myself, due to the cost of LS6 intakes, but cutting a hole in the hood has become cool again. Trying tl tuck my 454 under the cowl of my 94 Camaro would result in modifying a Torker 2 to accept 8 injectors, then using a cast elbow to take a TB.
The design in the beginning of this thread looks to me to be a tunnel ram for a Chevrolet or Mopar V8, for which there are already several different choices each. But by the time you guys got to the Indy design, that seems very interesting. Shame we can't just run those sexy Indy V8 Chevys in street Camaros.

 

I know the race Ecotec has topped 1200 horses, but what turbo 4 has made nearly 3000?