Increasing Plenum Volume on TFS A460 Tunnel Ram? Cheap power or waste of time?

I have 12:1 598" pump gas engine with the TFS 3X casting heads and Lem's chamber with TFS CNC, 2.400 TI intake, 1.88 SS exhaust. The manifold is the older (heavy) TFS tunnel ram ported and cleaned up inside by Wilson Manifolds to match the cylinder heads all back in 2012.

Cam is 282/294/113 .850"/.830" Comp roller with .904" Isky Max. Operating range at track is ~5800-7800.

I've seen a number of non-385 buillds over time quoted as having too little plenum and I'm inspired by the (505"?) Blair Patrick FE in Scott Miller's Drag Week Cougar that went very low 9's all week at DW 2017 and won Street Race BB/NA. It has about a 2" thick wood plenum spacer and that gor me thinking about doing the same on my 598" BBF.

Has anyone played with this and gotten good results?

I doubt most have even plowed as much ground as you already have. Do you have anyone that would/could machine a spacer from phenolic? If not, I'll see if the  dudes at Jomar would do it.

Mr. Fowler, good to see you’re endeavor still moving forward. You’ve been pretty silent over on BS.

That FE Cougar sure runs well!

Keep us posted on your progress if you do any testing.

Lem, I was originally thinking of starting with plywood or some other laminate that I already have tools to cut with. The alternative being water jet cut spacers (phenolic maybe). I have a good friend who runs a water jet job shop and I was thinking having him make four 1/2" thick versions to experiment with using the gasket as a loose template.

I am doing something kinda like that but with a more lower hp engine and much lower priced parts. I am going to do a dyno on my (to be built parts are ordered) 521 BBF. I am going to test a dual four weiand intake with a pair of 750 edelbrocks and then 750 3310 vacumn secondary Holleys and today I just ordered a manifold to that I will modify for a pair of 1050 dominators. This next summer I will also try the dominators against the best of the smaller carbs at the track. The weiand just looks to be pretty darn good as the entry into the bottom manifold is going to be pretty straight. Phenolic spacers are readily available fo the smaller carbs but not sure about dominators.

57ford Custom that is an interesting alternative idea to use carb spacers under the throttle bodies (this a dual four barrel throttle body EFI deal) as opposed to adding to the plenum overall with a single large spacer.

windsor wrote:Mr. Fowler, good to see you’re endeavor still moving forward.  You’ve been pretty silent over on BS.

That FE Cougar sure runs well!

Keep us posted on your progress if you do any testing.

All my "testing" has been at Drag Week, and the four NMCA West events this year. I owuld describe the last two years as transmission destructive testing. Broke the AOD (planetary falied after 9 years, I can't complain) at Drag Weekend West 2015, killed "ProMod" glide at DW16, killed Glide again first time we sprayed at year end NMCA in October. Car with me in it is too heavy and too slow for Glide N/A so I'm going give the AOD another shot this coming season with the right rear gear and more optimized converter. Plus the odd engine improvements and a further diet car and driver.

Wow, breaking that expensive, aftermarket, supposedly bulletproof glide and going back to a “stock” AOD.... did you always run 2.4 stock ratio or the 2.84 4R planets?

Dan Gilsdorf (SilverFox Trans) and Darrin Burch (DC Trans) have really progressed the AOD/4R trans in recent years so if you haven’t talked to them you may like to. They’ve supposedly made some modernizations and upgrades to what Lentech can do.

Hopefully my C4 will last out this coming summer but if not I would love to go with a (supposedly) bullet proof AOD. Yes I know nothing is bulletproof

windsor wrote:Wow, breaking that expensive, aftermarket, supposedly bulletproof glide and going back to a “stock” AOD.... did you always run 2.4 stock ratio or the 2.84 4R planets?

Dan Gilsdorf (SilverFox Trans) and Darrin Burch (DC Trans)  have really progressed the AOD/4R trans in recent years so if you haven’t talked to them you may like to.  They’ve supposedly made some modernizations and upgrades to what Lentech can do.

It has the 2.48 planetary, it would better with a 2.20 or 2.10 1st but there is no such thing. The Reid Case shorty PG with the Gear Vendors OD actually weighs more than the AOD/Superbell and is an inch shorter. The AOD is already repaired, work done at Hughes with some Lentech bits and pieces.

I'd be curious about what new can be done, as is i'm limited to about a 1000 ft/lbs. torque with the AOD.

Sounds good. 2.20 or 2.10 would be fantastic, but unlikely. The builders usually like the 2.84 4R gears because they’re stronger, but I’m sticking with 2.40 with my BBF as well.

CDMBill.

I already have about 1/2 dozen TFS plenum spacers already made out of UHMW nylon. They are of various thicknesses such as .125" through .625". I'll be glad to send them to you and you can test with them and settle on whichever width works best for you.

Charlie Evans

Get ahol of Kim Smiley here, aka Maverick.
He had a whole 4x8 sheet of plywood laser cut for spacers. They are two-piece. But you have to grind the taper in the one piece...

I'm talking about TFS tunnel ram plenum spacers. I think 72 Mav must be talking about carburator spacers, when he said grind the taper in the one piece.

C.evans

Plenum volume up to 100% of displacement...never seen it hurt power, always seems to make more.

c.evans wrote:CDMBill.

I already have about 1/2 dozen TFS plenum spacers already made out of UHMW nylon.  They are of various thicknesses such as .125" through .625".  I'll be glad to send them to you and you can test with them and settle on whichever width works best for you.

Charlie Evans

Charlie, I'd like to take you up on that offer. My manifold as shown in the picture is the older thick version and is stock except for Wilson's port work and smoothing of the interior to match Lem/TFS' port shape and taper.

My understanding of the plenum volume concept is pretty limited, I had thought that the ideal size N/A was at least the displacement of the engine, but see Scott's comment above.

Charlie if you know offhand the volume of the TFS tunnel ram plenum then maybe we can narrow down the number of spacers to try? That you have them down to .125" tells me this can be a pretty exacting science. As noted this is a 598" 4.6 bore by 4.5" stroke deal. Best ET Operating range has been 5800 to 8000, converter at the hit flashes off the brake to ~5800, shift recovery is ~6400 shifting at ~7800. I'm staying with the dual Accufab 2200 CFM four barrel throttle bodies as they have good drivability and I can sorta see over the whole package when driving.

I can PM you shipping instructions and please let me know how best to pay for them.

Thank you in advance. I'll share what we learn.

IN general use:
short ports like small plenums
long ports like bigger volume plenums
large ports like big plenums
small ports like smaller plenums

Therefore ... a big, short port is anybodies guess.

Bill,

One time a few years ago Lem and I got together and figured the plenum volume of that manifold. We actually came up with 429 cubic inches. What the deal was that we had a 572 cubic inch engine at that time and the theory was 75% of the engines CID, so then 429 cubic inches of plenum volume was "spot on" that 75%.

I know that there is a school of thought by some people out there that plenum volume can be or should be 100% of the engines CID. However, one time a few years ago when we had the Ford Winter Tech Seminar at the Executive Inn here in Owensboro, a couple of our guest speakers were Dave Bamber from Bamber Engineering and Jon Kaase. At that seminar during the question and answer session I asked Dave Bamber what was his formula for proper plenum size in tunnel ram manifolds? Dave kinda wanted to avoid that tough question and from the podium turned said let's ask Jon Kaase. So Jon stood up and said that he did not know what the perfect formula was, however he had learned that whatever size plenum gave the most power on the dyno,, that one size SMALLER ran better when going down the track. In other words a slightly smaller plenum gave better drivability because of the increased throttle signal and etc.

On my own Top Sportsman car, just this past couple of years "I Think" I am learning that lesson in regards to carb sizing. We have a 706 CID engine and I had Darin Morgan and his brother Brad Morgan build the billet runner intake manifold, so it should have been dang close to perfect. I also have a pair of 1450 cfm carbs and two pairs of 1250 cfm carbs. The 1450 carbs make more power on the dyno, but driver Mark has wanted to switch back to the 1250 carbs on the engine to run down the track. He says there is a slight bog coming off the line which I can not hear, but it shows up on the computer graph after the run with the 1450 carbs. He has gotten rid of it by switching to the 1250 carbs.

So my current theory is; if the plenum size is too small, you can recover some Hp by going with too big of a set of carbs, AND going with plenum spacers. Then the inverse is true, if the plenum size is too big, you can recover some carb signal by going with a smaller pair of carbs and removing plenum spacers if you have any in there.

Hope this hepls,
Charlie

Charlie:

Definitely interesting information. Not sure if its an advantage, but as I run port injection EFI with two large throttle bodies I no longer have to worry about signal to the carbs. That said we made a small but measurable improvement in power on the dyno using a large 16" diameter, 4" tall air filter squeezed into an oval shape around the two TB's. I built a Lexan box for it and when at the track I have facing forward and I see as much as a .02 improvement in KPA down track, meaning I'm getting a bit of ram effect. I have not tried the box without the filter yet. I reverse the box making it a rear facing scoop for street driving to keep excess dirt and rain out. I haven't tried that eitther as making multiple A-B-A test passes just doesn't;t happen at the events I can get to, and renting a track is not in the budget.

Bill

To echo what Charlie said, I've never heard anyone come up with a real "formula" for plenum volume. I mentioned displacement as most will say that's about max. I've played with it some with spacers on BB Chevs and in those cases, never made less power with more volume. All three engines I did that on ran really well down the track but none were max effort deals. It's usually a trial and error thing. I worked with an engine design software that gave me some volume calculations that I went with and they seemed to work real well. We did a bunch of spacer testing on the dyno when I was at Dart working on Powuk's PS program, but that was more of a tuning thing.

CDMBill wrote:

c.evans wrote:CDMBill.

I already have about 1/2 dozen TFS plenum spacers already made out of UHMW nylon.  They are of various thicknesses such as .125" through .625".  I'll be glad to send them to you and you can test with them and settle on whichever width works best for you.

Charlie Evans

Charlie, I'd like to take you up on that offer. My manifold as shown in the picture is the older thick version and is stock except for Wilson's port work and smoothing of the interior to match Lem/TFS' port shape and taper.

My understanding of the plenum volume concept is pretty limited, I had thought that the ideal size N/A was at least the displacement of the engine, but see Scott's comment above.

Charlie if you know offhand the volume of the TFS tunnel ram plenum then maybe we can narrow down the number of spacers to try? That you have them down to .125" tells me this can be a pretty exacting science. As noted this is a 598" 4.6 bore by 4.5" stroke deal. Best ET Operating range has been 5800 to 8000, converter at the hit flashes off the brake to ~5800, shift recovery is ~6400 shifting at ~7800. I'm staying with the dual Accufab 2200 CFM four barrel throttle bodies as they have good drivability and I can sorta see over the whole package when driving.

I can PM you shipping instructions and please let me know how best to pay for them.

Thank you in advance. I'll share what we learn.

Bill, would you just call me please tomorrow morning at (270)302 dash 5842. Thanks, Charlie

rmcomprandy wrote:IN general use:
short ports like small plenums
long ports like bigger volume plenums
large ports like big plenums
small ports like smaller plenums

Therefore ... a big, short port is anybodies guess.  

Randy: what defines short or long port/ large or small runner on a given application?

The selection of cast tunnel ram manifolds for the TFS-A-460 is pretty limited, so adjusting plenum volume seems like a relatively inexpensive variable. My assumption (yes, we all know what that means) is that the orginal design was optimized around a particular application. Was it a 500" 9000 RPM PS motor circa 1982? Seems like someone would know.

Bill.

I know you asked Randy, so I apologize to him beforehand. The original design TFS A-460 tunnel ram was designed by Mike and Rick Smith back in the late 80's if my memory is correct. Somebody correct me if I'm wrong. That manifold had long curved runners and a smaller plenum. It's nickname was "the Holmes" manifold. Very few were cast in magnesium with the rest being cast in aluminum. I think Lem had a magnesium one and later on I had an aluminum one. That manifold took advantage of the second harmonic I think, probably in the 6200 to 7000 rpm range. Later on in 2000 & something, TFS redesigned the tunnel ram into the one we have today that says Serious Horsepower on the side. This manifold has shorter runners and a bigger plenum than the Holmes manifold. It seems to work in the 6900 to 7700 rpm range and I'm going to say its a third harmonic design.

Now then, then things that make all of this a floating target are the engines rpm range, the engines cubic inches, how well the intake port flows, the carburater size, plenum size, runner length and other factors such as the header primary pipe length. The software calculator program for a "tuned engine" that a lot of guys use seems to be Pipe Max.

Hope this helps,
Charlie

CDMBill wrote:

rmcomprandy wrote:IN general use:
short ports like small plenums
long ports like bigger volume plenums
large ports like big plenums
small ports like smaller plenums

Therefore ... a big, short port is anybodies guess.  

Randy: what defines short or long port/ large or small runner on a given application?

The selection of cast tunnel ram manifolds for the TFS-A-460 is pretty limited, so adjusting plenum volume seems like a relatively inexpensive variable. My assumption (yes, we all know what that means) is that the orginal design was optimized around a particular application. Was it a 500" 9000 RPM PS motor circa 1982? Seems like someone would know.

EXACTLY ... it is all relative to what you are comparing it to at the beginning.

....wrong thread