Are plenum spacers available for the Holley Stealth Ram? Perhaps
adapted from one of Wieand's non-EFI tunnel rams?

If so, are these divided or open inside? What thickness(es) of
spacers are available?

Manufacturer, p/n# and on-line source?

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Why would you want one?

 

it wouldnt clear a stock hood...dunno what youve got, just thought id mention it

 

I would like to move torque & HP down by increasing runner
length.

From Paul L.'s information, the HSR runners + the port = 12.26"
Using the Bowling and Grippo Intake Runner Length Computation

12": For 4th/3rd harmonic, RPM range is from 5613 to 8228
13": For 4th/3rd harmonic, RPM range is from 5294 to 7760
14": For 4th/3rd harmonic, RPM range is from 4916 to 7206

By comparison, crunching the Super Ram (21") through the same
calc displays
21": For 4th/3rd harmonic, RPM range is from 3277 to 4804
(peak tq just above 4,000)

I am not aware of an EFI manifold that slots in between the
runners lengths of the SR and the HSR.

Sigh, unfortunately true.

I've been mulling over intakes for awhile and am at a point where
I've accepted that the hood needs to be modified or replaced for
the HSR to suit my needs.

My starting point is an '89 L98 A4. So to make best use of the
operating range of the stock HSR, I am looking at a beefed up
bottom end with lubrication to match; more head, valvetrain,
camshaft, fuel, ignition; a converter and rear gears to cope
with the elevated RPMs.


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Street and Performance's "Multi-Port Injection" system is similar to the StealthRam (or vise versa) and they offer a 1.75" and a 2.25" riser for that intake as a $75 option. From the looks of things, it doesn't look like it will bolt up to the StealthRam though. It might be possible with a little fabrication (maybe welding) it could work.

I tried to buy just the intake from these guys before the HSR came out and they wouldn't budge from selling it as a $2,000 kit with electronics. They wouldn't even sell me just the fuel rails,,, which originally he said they would and get back with me on a price,,, but after 5 or 6 phone calls of him promising to call me back I dropped it.

At any rate you might want to see if they'll just sell the intake with the spacer,,, or just the spacer - maybe your luck will be better than mine with them. They're website is not very user friendly but it is www.hotrodlane.cc

Here's an article that has a picture of the unit with a riser in a truck.

http://classictrucks.com/features/0510cl_69chev/

Definitely going to need a 3" or higher hood for it with the 2.25" spacer.

HTH

 

Although I know about S&P, their EFI manifold(s) never came to
mind.

I didn't see any information about the runner lengths, I'll look
again when I am fresh. In the images, it looks like the addition
of the spacer makes the Multi-Port and the Ram-Port appear
much larger in size than the HSR.

I wouldn't try to adapt their spacer to the HSR. If Holley/Weiand
or the accesory market offered one, I would consider it. Otherwise,
I'd go to my machinist.

Thanks for the input and the links. Very helpful.

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Yep,, it would be realtively easy to machine a riser/extention plate for the StealthRam.

I'm not aware of Wieand ever making a riser for their part #1984 tunnel ram,, but if they did,,, that'll be what you're looking for.

I'm a big fan of inertia tuning myself and have been in the process of modifying one the the FIRST injection intakes. I'm confident based on the number of engines I've built that it will deliver what I expect, but I'm worried I might not be able to get enough traction to get the 1/4 mile times l'm after.

As a backup, I recently bought a Wieand dual carbed plenum (for their #1984) that bolts to the StealthRam. If I run into traction problems with that FIRST unit, I'm going to switch to the StealthRam and rig up dual 750 cfm throttle bodies for it. This plenum adds about .75" to the length of the runners which is not much.

 

I wonder how hard it would be to modify the stock plenum to be mounted to a tunnel ram intake. At least i know of two people with a welding rig capapable of welding aluminum. I know it may not be cheaper but i only know of one company that even do this and I think it looks hotter than the Stealth Ram. If anyone knows of the tunnel ram intake part # for the intake with the bosses for the fuel rail I would really appreciate it. Ive only seen this intake once so far. Sorry dont mean to hijack the thread but figured that someone here would know about tunnel ram intakes. Ill make it its own thread if needed.

 

After reading through all this I don't see how the plenum spacer will increase your runner length. I can see it increasing your plenum volume which is not a bad thing. Remember this is fuel injection and you are talking about dry air versus a carb set up.

 

Ok, I've been busted.

The title DOES say what it says and you are right, a 'Plenum
Spacer' will increase plenum volume, not increase the runner
length.

However, an internally divided spacer inserted between the
top of the manifold and the bottom of the plenum in such a
way that it seals tightly to the tops of the runners, transitions
smoothly and effectively extends the runners will have the same
effect as if the manifold had been cast with longer runners.

Just visualize the divided section in the image BadSS posted
extending to the top of the carb plenum. (I think the dividers
are only really present on the carb adapter to smooth flow
over the flat ground runner tops.)

I am not in a hurry to change the plenum volume. There is a
relationship between the plenum, cylinder volume, and number
of cylinders. I haven't come across a volume measurement for
the HSR plenum, yet. So I will seal and measure mine, take a
look at how the number fits against the theory, then decide
from there.

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Okay I see what you are talking about. Then the runners will extend to the top of the spacer. You will have extended the runner length per your plan. But now there will be a sharp right angle from the larger plenum to the individual runners. Flowing air does not like to make sharp turns.

The way it is now there is a small plenum for the group of 4 runners without a sharp right angle. This would help smooth the flow into each individual runner.

Not sure how this would work out. Only way would be to try it with and without the spacer. With my modified TPI I have been trying to kill off some of the low end torque. I'm down to a runner length of around 12 inches. I still have more torque at the rear wheels than the original TPI setup had at the flywheel. I suspect I have increased the torque even more with my latest mods. Will be at the dyno next Saturday to find out.

 

The stock runners on the HSR just end abruptly. It isn't pretty,
but that's how Weiand/Holley do it.

I agree it would be nice to have them terminate in a velocity
stack formed within the plenum.

But first create a length that moves the theoretical range
lower to where it is desired.

Sounds like extending HSR runner lengths is uncharted
territory. Doesn't seem to be ready-made spacers available
at this time.


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Here's what he's talking about doing with the StealthRam. The air will make the same turn into the runners with the same plenum whether the intake's runner length is 6.25" or 8.5" with a 2.25" extension (which will have holes cut in it to match the intake's runner opening).

 

Nicely illustrated.

Speaking purely speculatively, what would you think about two
25-30mm TB's driven by a common shaft and mounted on the
side of the plenum in line with the fore/aft runner clusters.

One would have the TPS and IAC mechanisms, the other is
just a slave.

(Rather awkward to package - think Mel Gibson in The Road
Warrior. But set that aside.)

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Okay that makes sense. I was going by the 1st picture that I thought was the real deal. I like the experimentation into uncharted territory.

You should be able to have the parts machined up. After all its only money. Hehehe. When I modified my SLP runners, the local welder and I became good friends. See attached picture.

 

Someone on a budget could fabricate most of the spacers out
of aluminum bar stock and plate or strip. Or hardwood.

The outer dimension of the runner clusters is just under 5"
Picture taking a 1"x1" piece of bar stock and cutting 8 pcs.
Assemble these into two spacers. Picture taking 3/8"x1"
strip stock and cutting 4 pc. Notch each so you get two
interlocking pairs. If you left them a little long, you could
cut ears at the ends. The ears could engage into notches
in the inner sides of the spacer.

Take the finshed pieces to someone to have them surfaced.
Or if you are bucks down, sand them on a slab of glass. Or
simply use LOTS of sealant.

Presto - 1" HSR runner extensions. No outside machining
or welding required.


When I saw the numbers in your sig, I could tell that you had
gotten really creative somewhere.

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I don't know if it would be that hard to set up or not,,, looks very doable to me on the StealthRam. See below. That would cure the front mounted throttle body hood clearance issues on the Firebirds also.

I actually thought about dual side mounted TBs on the FIRST unit. It has a provision on one side for a side mounted T/B and it wouldn't be all that difficult to get one mounted on the opposite corner on the other side,,,,, but rigging up the linkage for that surely would be problematic.

 

A flat plate milled out with a closely resembling pattern should work.
Through holes for the plenum mount will work and use long socket head bolts.
Need to probably port the spacer to match the plenum and runners.
Nice runners BTW
The problem there is like was said before, your setup with the LTR's needs the runners shortened. By opening them up the plenum volume was actually increased as the runners went down.
This has the opposite. Need to add to the separate runners only.
Something like this. (just roughed out the sketch, not to scale or anything)

 

It is just that sourcing a 2" thick piece of aluminum with those
outer dimensions and then having someone machine it could
prove to be a show-stopper for many budgets.

BTW - another DIY approach I didn't mention earlier is to just cut
spacers out of plywood. By making several, it becomes possible
to easily tune by adding/subtracting sections. Before there were
phenolic carb spacers, plywood ruled.

If there were enough interest, the ideal way to go would be to
have spacers cast at a small-volume foundry. There are at least
two in my community. Perhaps Holley/Weiand might be able to
help, too.

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Going in the other direction, technologically.

Someone out there has to be associated with firms capable of
doing Rapid Prototyping.

Just create an accurate CAD drawing, hand the file over to a firm
with stereolithography equipment and get back wax parts for
making molds. With laser sintering equipment, I believe that
they can make polycarbonate &/or nylon parts - these would
possibly be ready to use as is.

Another material might be powdered metal. I recall reading
about being able to prototype PM parts when I came across a
firm offering quick turn-around and on-line quotes a few years
ago.

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Rapid prototyping is very expensive and the material that is used in this process is NOT the regular production material.

I think your best bet is to find a machine shop which will machine your spacer from drawings that you supply. They could machine aluminum or better yet nylon. And I have no idea what this would cost you.

 

I had wondered about the price. There are on-line sites that
offer work for amounts in the order of $199, IIRC, but ...

Incidently, I contacted Holley to ask whether Holley/Weiand
carried runner extensions for the HSR or the Weiand tunnel ram
I believe the HSR was based on - I was told that they do not.

Thanks,
Ken R.

 

That looks easy to cut out with phenolic. Of course you need a mounted router to make it work. I watch phenolic get machined all day at work.

 

What is the deal with phenolic?

Is it typically cast to near net shape or is it produced in sheets/slabs
and machined to shape?

If cast, how complex is this? Is it a case of mixing a resin & catalyst,
pouring and waiting for the reaction to complete or is it one of those
multi-step operations involving pressure, heat, nasty by-products
or a combination of the above?

The former you could do in your garage, the latter would perhaps
be better left to the pros.

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The dual TB setup is an outstanding idea! It would be very efficient. However, you would need more material (runner) than just affixing the TB to the intake as-is. A "plenum" is needed - there is essentially no plenum area and consequently would not perform well. If an extention came off of the manifold base and put the TB's further away, you'd be looking at a damn fine setup...

 

Actually you can buy phenolic pieces from Mcmaster Carr. It actually machines similar to wood but has many anti chemical properties. A 12" by 6" and one inch thick piece would run you about $30.

 

Cutting out the openings for a phenolic extension(s) should be easy enough. I'd still call and see if that Street and Performance extension would work or not. I doubt they have their own castings and it's possible Holley/Wieand might be making the intake for them and if so,,, their $80 extensions might bolt right up to the StealthRam.


The dual carb plenum is open from side to side and the throttle bodies would sit up off the runners. I guess this is why they make 6" cowl hoods! This would look rather menacing under the hood,,, and I'd have to run this set up if I was doing an old roadster with an open engine bay.

 

Thank you for the source.

About having a mounted router. I imagine a shade-tree alternative
would be to mark an outline and then drill a series of holes to
follow the contours of the outline. Straight runs could be opened
using a key-hole saw to cut between a hole at each end of the run.

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how much could that double throttle body increase airflow ?? im just curious lookes awesome. Also isnt this restrictive ??? to airflow and if so is there an easy way to get rid of it and still have ability to torque bolts correctly ??

 

If you run dual 750 T/Bs for a total of 1500cfm, that is worth around 4-5% peak power increase on a 600 horse 406cid engine compared to the 52mm front mounted throttle body - based strictly on the difference between 830cfm vs 1500cfm. On a 400 horse 350cid engine,,, it would be basically for looks as you would be lucky to see a 2% increase in power.

Air doesn't like to make a turn on a sharp edge. So,,, I beveled the edges of the StealthRam runners, similar to the inside of the dual carb plenum (pictured above). Still,,, I doubt this provided a significant performance increase, but it could only help,,, ever how little that may be. It's hard to see in the attached picture, but the plenum edges are beveled a little bit also. Depending on what I put the HSR back on,,, I may work that plenum transition area a little more.

 

thanks so if i could make a 600 horse engine with pro topline heads or whatever id make 30 to 50 horse more possible ?? great stuff

 

I don’t get it, if you’re going to go to that effort why not just make the spacer come up with proper bellmouths and into the bottom of the plenum, so the runners actually end in the plenum. Then you could even make the new plenum wider to end up with a similar area or even make ends of the runners bend outward to make them more then just an 1” or so longer.

As far as just a plane old spacer… hardwood and aluminum both machine rather nicely and it wouldn’t be a big deal to do. This was for a totally different application (an bored out crossfire setup), but I made a pair of these in a couple of hours one night using a drill press and some hand tools, and it took a day for them to soak up some aircraft dope and dry (to make them fuel proof)

 

I dont see how that possible with the stealthram ?? its just me i think but could you like put it on paint or something ?? make it easier

 

Has anyone taken this any futher than the talk in this thread? Interesting discussion here and I know it's over a year old so anyone still playing with this idea?

 

get me a dxf file and I could get you a quote on CnCing the spacer. out of what ever you want.

 

Actually yes....a member on Stealthram.com made 3/4" spacers for nitrous. He has yet to run it but the CNC pieces he has looks awesome.

 

I think what poster number 32 was trying to say can be seen in the attached picture. I don't know if this can be done to the Holley Stealthram or not. Interesting idea so let your imagination go wild.

 

Pic uploaded for Stealthram spacer.

 

I can visualize adding maybe an inch or more of runner with some fabrication skills and raising the plenum maybe a 1/4". However the runners would extend into the plenum area.

This could be a problem at the throttle body entrance. However if one were to use a monoblade then that would mitigate the restriction of the front runners somewhat.

 

As pictured, the nitrous spacers don't change runner length,
they increase plenum volume.

If the spacers shown in the image posted by YenkoST were
divided, keeping the runners separate to the top of the spacers,
this would effectively achieve my original aim of lengthening the
runner lengths. The work to make spacers open or isolated wouldn't
be much different, it is just a matter of realizing there would be
(at least should be) different impacts on intake tuning.

1989GTATransAm - I agree that velocity stacks at the end of
each runner as shown in the images you posted would be nearer
to ideal, but the HSR manifold base consists of two clusters
of four runners siamesed together. This packaging doesn't
lend itself to individual stacks at the top.

However, 83 Crossfire TA's point about improving flow with
help where the plenum transitions to the runners can be addressed
in other ways.

The nitrous plate image from YenkoST shows work to radius the
90º edges of the runner dividers. It isn't readily apparent,
but the length-wise divider is thicker, offering more material
to radius than the left-to-right divider. If there was an
infinite amount of time available for development, my vote is
that flow might be improved by ADDING width at the dividers
and then removing material for the optimum entry.

The other part of this is the perimeter around the outside of
each of the runner clusters. At the very least, some work to
blend the 'H-shaped' plenum opening to the runners should help.

Someone with time and skill might consider adding material to
raise the interior floor of the plenum around each of the openings
and then slope the added material up, around and down into the
runners. Effectively forming a velocity stack for the top of
each cluster. If you have seen the work LD85 did to section his
plenum so it fit under a stock C4 hood, that is probably what would
need to be done to get access to build up the floor with weld
(epoxy is heat-sensitive and might not withstand the heat from
welding the floor back onto the plenum.)

There is very little room from the rear opening to the rear plenum
wall, a bit more at the front. Still, the sides and the center
sections could benefit.

TPI383 - while not a .dxf file, some images here have Lufkin
measurements of the runner clusters. Click text for images.

Rough Measurement

• 4.875" Fore-Aft on Rear Plenum Cluster
• 4.250" (4.375" at bolt holes) Left-Right on Rear Plenum Cluster

Those images and other HSR ones that may illustrate the comments
earlier about the plenum floor appear at this link.

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I agree if you have the room just add a spacer with the runners in it. That would be the easiest was to go.

 

Just wondering. Is there clearance to make a custom plenum by widening it say a 1/2" on each side and extending the front/throttle body side a 1/2". This way it might be easier to extend the runners up into the plenum area.

 

The idea came back up in another post and I'm still interested in this.
TTT

 

Interesting concept.
If you were to make a spacer out of any material then something like this would work ; just not radiused so deep so as to give the runner length increase talked about

 

i think its a freaking shame really, companies like trickflow, and others can make 5 different designs each for 5.0 fords but maybe 1 for tpi, damn shame... i like the idea of making that spacer for a nitrous plate, because i believe there was some concern about nitrous distribution when using a stealthram with the nos 5151 system....

 

I know that I am way late to this thread but if anyone is interested I do have spacers for the HSR. I originally had them made to take care of a clearance issue but since I do not run the HSR anymore I do not need them. I'll need to measure the thickness but if I remember right they are 1-1/2" thick and are open.
If anyone wants them I'll make you a good deal on them and even include new Stainless hardware to mount the plenum and spacers.
I can post some pics as well if anyone wants to see them.

 

Ok, I was mistaken, the spacers I made ore 3/4".

 

Anyone ever measure the HSR's plenum volume? There is some really interesting articles on this site, and a pretty sweet gen 2 to boot!

 

I know this is an old thread but has anyone ever tried this now that they are available?

 

David Vizard mentions in one of his videos using a 1 inch spacer, and opening the front 4 runner entries up slanted toward the throttle body, and claims it is good for 25 hp.