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I believe I have TWM IR's on my car, which I believe use the same mountings as Webers for the stacks (2 screws). I believe they are 48 or 50mm.

Presently I have a short set that I use with an air cleaner setup, but I was thinking if I came across a set of 4" stacks for cheap enough, I might jump on a set for the occasional times I want to show off the injection.
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I found that TWM was bought out by Borla. I will have to measure to find out if they have longer stacks available.

I also think I'll be switching to a crank-trigger ignition, with Electromotive ECU.

Price is right for the whole system, I can install it myself.

This will be in a few months.
How about 5"? Will those fit? Show me a picture of how your stacks mount to the throttle bodies.

These are the stacks for the Webers. They have no mounting flanges. They are held in place by mounting tabs.

http://vwparts.aircooled.net/T...-550-p/52840.550.htm

I found this picture of what you had previously posted.

The 48 IDA is a different mounting method then yours are which are like the Delorto carbs or the Weber IDF series.

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  • MTS_velocity_stacks
Last edited by panteradoug
quote:
Originally posted by 4NHOTROD:
Careful of the screens you use. My old ones cost me over 50hp.


The best screen mesh has a 46% flow rate. In other words you loose 54% of the flow, more or less. So you need a screen with about twice the surface area of the stack intake to compensate.

I have not seen any that are premade like that. You actually need to make your own.

There are a couple of vintage pictures of Indy and Can-Am cars with that kind of screen on the stacks. I can't say that I have saved any of them.

The hard ass race teams understood this and the concept of not sucking in something under full throttle so this idea is not new.

God gave us all a brain with high capacity and some with operational capabilities? If you need to fall back on anything, this would be a good time. Hopefully it won't give you a migraine?
Last edited by panteradoug
These are the 5" tall stacks for 48 IDA's. With the screens they fit under the roof with about 1" of clearance over the screens which are about 1-1/2" high.

You need to make your own screens for them. These are mine. These have a surface area 247% of what a flat screen would. That means there should be virtually no restriction to them. Less anyway.

These, the tall stacks, also help with the fuel reversion caused by a conventional non-"Weber specific" cam with a high overlap. The cloud stays more in the stack because of their greater than stock height.

The Pantera can run them. Other cars don't have the hood clearances for them.

These are spun aluminum. Really nice stuff.


Stainless screens and rings, a la Shoppe d'Doug. Don't like 'em? Don't look at 'em. Read it and weep. Wink

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  • 2015-07-16_07.46.13
Last edited by panteradoug
I'm kind of striking out finding tall aluminum velocity stacks for my setup.

I'd love to find some 5" aluminum stacks similar to the shorties I have, and then I could do Panteradoug's screen trick to that.

I might settle for the steel versions if I can find a set that fits.

I may have to find someone who can help me mod mine, weld a center section in place.
Send him the pic of your stacks. It might help him.


I don't know how the 51mm designation on yours effects the situation?

The picture I posted should fit yours. At least the bolt pattern will and the trumpets themselves appear to be the same ones that I have.

IF your intention is to attach the screens like I have then you do not want the rolled over edges on top. There is no "flange for the rubber ring to attach to like on mine.



You are going to have to do something with keeping water out of all of them but mostly on #4 and #8. Those two will be completely exposed since the roof does not cover them.

The others although they are open as well are tucked up under the roof.

You just have to wash the car from a garden hose carefully with those. It can't go into a carwash any more (as if it ever did).

The Pantera "sugar scoop" roof spoiler that came on th L's becomes functional with an IR induction system especially with tall ram stacks like this. It directs the air coming over the roof into the intake area of the stacks.



The taller stacks also change the frequency of the sound that the engine makes at full throttle. I suppose it is like playing a trombone which has a slide tube to change the notes it plays.


Someone had actually done a flow test on these things and said that the wider mouth opening increased the flow through each runner by 25cfm over the stock Weber stacks. It seems like a lot but there is logic to a reduction in restriction of flow.

I think it was one of the VW people but they don't use the tall stacks like this, just the wide mouth stacks.

How this effects a TB system, I don't know? You will find out.



On 48 IDA's you can change the "venturis" and that does effect the flow of the carburetor.

Stock, IDA-4's come with 37mm "chokes" (venturis). The Ford GT40's used 42mm ones and those carbs were designated as IDA-1.

This is all with 48mm throttle bores. Yours are using 51 mm throttle bores so those give the engine different characteristics in where the "torque curve" comes "in" as does the id of the header tubes and their lengths.

WEBER says the 48 IDA system with 37mm chokes flows 2400 cfm. 300cfm x2 x 4 carbs. That is 300cfm per intake throat. That is right around where you want them but is becoming restrictive right there.

42mm would be better putting the system right around 320-330cfm especially with a less restrictive "trumpet". Now you can see how changing these parts "tunes" the intake flow and power range of the engine?

This is also where the lift of the camshaft has to put the intake flow of your heads into the 300 to 330 cfm vicinity. That information is determined on the flow bench.

From what I have seen the lift of the cam needs to be .600 or more and lifts over about .630 no longer are adding any contribution to that flow. They are just adding unnecessary stress to the valve train? BUT even if they did, the induction is already at it's limit and maxed out. Wink

ALSO, I too am using that Hall Pantera intake manifold. Even though a 51mm throttle plate will flow more cfm, the manifold runners are at their limit somewhere right around there (as cast). The runners right under the flanges need to be worked in order to use the additional flow.

On mine, that flange was as delivered machined exactly at 48mm.

On yours, you would see that immediately when the TB's were off for the o-ring repair. You would see on the mounting flanges where there was work with a die grinder done AND the throttle plate opening in the intake flange enlarged to 51mm.

I have had BOTH of the Hall manifolds and there is a diffeence in the casting between the original 4v head manifold and the A3 "raised port" manifold. You want the "raised port" manifold. It has better line of sight to the intake valve but that only matters if your throttle plates open on the inside rather than the outside of the port. You gain throttle response opening on the outside.



If you noticed the rpms used in the youtube of the blue Pantera on the track, it never goes above 6700 rpm and rarely below about 4,000rpm. That is where that car is "tuned".

Simply put, you do not need an engine that turns over 7,000 rpm. As tuned it will even pull with a 427 which is what I said about driving a 427 Cobra and a Gp4 on the same day.

I actually thought the Pantera was faster. It certainly was dialed in better than the Cobra was.



With a Pantera with IRS, independent runner system induction, you are actually tuning the system to the car and the way the engine and induction fit into the body of the car. If you put this exact system into another body and chassis, you need to start all over again. It will not be the same solution and it will not give you the same results. Big Grin



OH! Almost forgot! There was an Aussie selling stacks to fit both setups on Ebay. His solution was to take a 48 IDA stack and make bolt on flanges that clamped the stack to whatever you were using. That made the stack a modular system by the adjustable bolt on clamps.

Trouble is I can't seem to find the guy now? I will search again later.
My engine I was told has C3L heads, and with the TWM injection manifolds, looking down the throats it looks as if everything has been matched.

The engine pulls WAY past 7000, but I really won't ever be revving it that high. I'm just happy to have it back up and running.

The taller stacks I want mainly for looks. I know their lengths affect the engine behavior, lots of engines have telescopic stacks to take advantage of this (Mazda, Ducati, KTM, all used, and presently use variable length velocity stacks).

IMO there's just nothing cooler than 8 tall stacks sticking up high like the ones in the video of the white Pantera.

I hope to run 5" stacks with the same screens and rubber attachment that Panteradoug has goin on.

Not worried about water. Car's on slicks, and will never see water or rain. Washing's done by hand and polish and spray bottles.
quote:

I hope to run 5" stacks with the same screens and rubber attachment that Panteradoug has goin on.



Big Grin



[/QUOTE]
Not worried about water. Car's on slicks, and will never see water or rain. Washing's done by hand and polish and spray bottles.[/QUOTE]



I try to prepare the car for the unexpected. Here in the east this time of the year it is not unusual to get sudden deluge out of no where.


Albert Hammond - "It never rains in California"


Also you have to look out for someone else's kid or maybe a girlfriend who wants to help out and surprise you...the car... with a surprise wash job. Wink


I wash my engine too. "it's a clean machine". Cool
Borla got back to me. They're going to have to make a new set from billet, and it's gonna cost a cool G.

I'm gonna have to put that one on the backburner for a spell, althogh, my car WILL have 5" velocity stacks someday soon here, along with the flat black paint/wrap treatments, and Snow White will have a sexy little set of changes that will improve her look a lot I think.
Looking back on the ad for my car, it says my IR bodies are 48mm.

Does this make anything easier?

I see some ebay offerings that say they come in 48mm, but they're straight, and steel, and I'd rather have tapered and aluminum.

If I could get my hands on a set of 48's like Panterdoug's, I know I could have the mounts welded myself.
OK. Let's try this again? I thought I posted this link but I don't see it now.

http://vwparts.aircooled.net/T...-550-p/52840.550.htm

I think that you can use these but will either need to use the mounting tabs for the 48ida's or make your own?

IF you could get hold of a "stock" 48 ida Weber velocity stack and try them on your TB's you can confirm or deny them?

I am surprised that there is so little help coming your way with this issue?

It could simply be that the individual EFI guys don't talk to the Weber carb people?

Inglese SHOULD know this.

If you can't find anyone locally to lend you a Weber stack, I can. I just thought it would be no BFD to find a local to lend you one?
couldn't you take one of yours off, trace the flange and bolt spacing. then use that to find a match?

looks like some one would make a short base with a "coupling" that would allow you to change stack lenght as desired.

besides containing exhuast inversion and looking cool, does the tall stack provide a performance advantage
quote:
Originally posted by JFB #05177:
couldn't you take one of yours off, trace the flange and bolt spacing. then use that to find a match?

looks like some one would make a short base with a "coupling" that would allow you to change stack lenght as desired.

besides containing exhuast inversion and looking cool, does the tall stack provide a performance advantage


I think that many of these throttle bodies are actually second generation derivatives from the 48 ida's.

You need an actual Weber stack in your hands to see if the stack fits in the TB and if it does what are the complications...if any.

I'll lend you one. Keep it as long as you want. Send it back eventually.

With Priority Mail it is two to three days away and will answer a million questions in just one try.

The tabs are not welded on the IDA's. They are loose tabs or fingers that apply pressure to a ring that is integral to the stack.


Inglese isn't everything. In some cases, not all, I have better, more specific information that he does. He's more generic because of the nature of what he does. I'm item specific.

That's a big difference. Smiler


...oh, and I don't cost anything either. Just one little drive...let's see, where's 10,000 rpm on the tach? Eeker
Success!

I found an outfit that had 8 aluminum stacks and I ordered them up.

We were pretty much on the same page as far as 48mm and IDF mounting, so (knocking on wood) all should hopefully work out well.

I've got some cool ideas using my air cleaner baseplate, and foam, to seal the underside of the stacks from debris being blown up from underneath the decklid, and I'm going to add side scoops where my side windows used to be.

I'm going to use Panteradoug's rubber screen mounting trick (if he'll show me), and some screens on the side window scoops ought to have my setup seeing clean air and looking as cool as it gets IMO.
I have some o-rings for that which I never used.

They are for making the GT40 type cookie tray.

The o-ring fits into an aluminum, or better yet clear plexiglass sheet.

The o-rings sit around the throat of the velocity stacks.

I would recommend the clear lexan so you can see what's going on underneath.

The problem with this setup is it positively seals you away from access quickly under the sheet.

On the FI that is probably less of an issue than with the IDA Webers. Those you need instant access to the throttle linkage or else you are inviting a problem.

What problem? That is unknown. That is the issue...access instantly to an unknown or unforeseeable issue.
What you describe is what I had in mind, but I'm going to use my lower air cleaner plate, held in place by large O-rings, with foam around the underside of the decklid to form a seal.

This will keep crap from being sucked up from under the car and up above the decklid.

Then I plan to fabricate some side window air scoops (or buy some pre-made ones), add some screens to those too, and along with your rubber screen trick, I should have the look I'm going for, with little to no restriction, and it should stay relatively crap-free while driving down the old dusty trail.
Scoops replacing the windows work but when they are made out of solid materials they will block your view necessary for picking up cars in the blindspots.

I have the "factory" fiberglass "bat ears" but put them on the shelf and this is the scoop I'm using now. It is vacuum molded out of clear lexan.

The screws you see are necessary to hold the gasket to the car at speeds somewhere over about 75 mph.

The scoops catch enough air that they will get ripped out otherwise.

Functionally some have found that it is better to just take out the glass and run without it.

It sure helps a lot for additional access to the engine compartment.



Unfortunately you can't leave the car parked anywhere unattended either. For one thing little pecker heads with screw drivers will come trying to pry the medallions off of the car to put onto their stunt bikes.

The other thing is they will start grabbing at things on the car like the scoops to see if they will come off of the car with a yank.


I'm working on a security system that when it is turned on, if you touch the car and you are grounded, you get a jolt of full power from the battery through anything metallic.

I want to test it on those little wankers that you see at the beach with the frizzy hair and the clogs. I want to see it the battery turns their hair straight? I'd prefer their hair to catch fire but that might be considered extreme by a third party? I'm not sure about that yet?

Unfortunately my version of "the club" doesn't work in the Pantera. There is no place for the 400# gorilla to hide in it but just the thought of one popping out of the trunk with a club and using it on the perpetrator is like Schwepps..."curiously refreshing"? Wink

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  • 2015-07-29_19.45.18
Last edited by panteradoug
Stacks arrived today. They look fantastic.

I'll try to get them installed here shortly.

I plan to utilize the lower air cleaner plate to help seal off the decklid, and also to hold the temp sensor that's mounted into one side.

The correct O-rings ought to let me position my baseplate where I need it.

Some 1' or 1.5" foam, cut to shape ought to help finish the seal between the decklid and air cleaner base. Then I'll have my stacks sticking out, all sexy and all, and then I plan to install the screens like Panteradoug's setup.

I think it may even improve performance a little, but that's not important. These stacks are for looks.


Tomorrow morning I go on my search for O-rings and foam sheets.

The end result is gonna be SICK!

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