Cross ram intakes

Andrew,
OOOOOH YES ! You really have tried a Moon manifold havn't you, echo everything you say. To be fair we have only used them on small displacement engines for which they were originally designed, 327 max. and 461X heads at best.
At 6000 it was like flicking a switch, the motor just stopped and the fuel stand off just about gassed the driver.
We had the cam ground at 112 or 114 lobe center and with two exhaust lobes so we finished up with a mirror image arround TDC which certainly helped, torque was great all the way through, you could almost run a whole race in top gear, but HP with 45 DCOEs was always about 400.
You can hog the manifold out and go for 50s but still not much better.
Love the bit about fuel consumption, the Bizzarinnis we did always had to carry about 40% more fuel than something like a Cobra, just something else for the owner to moan about !
Mike
 

Kelly

Lifetime Supporter
I really enjoy the discussions on induction systems. I would like to add that all the inductions systems being discussed as “Cross Ram” systems in this thread are actually quite different in their characteristics. In general, Cross Ram is a remark about the appearance horizontally positioned runners but in practice they are forms of Individual Runner and Common Plenum induction systems; and there are several variations in themes within these two categories.


The Sheet metal intake that started the thread is actually identical in type to the original polymer LS intake though it has the plenum on top instead of under the runners compared to the original. I presume this intake was made to adjust runner length and or (optimum) cross section for a higher RPM and/or horsepower target than the original LS intake could support. As an aside, the original LS intake is a very good piece and produces excellent performance across a broad rpm range with peak power routinely North of 600 HP on 427 CI mills and does so with a very low profile that fits under the hood of street cars. FAST makes versions of this intake which are identical in embodiment but have different runner length, runner cross sectional areas, throttle body choices, and plenum volumes, all of which can provide subtle performance improvements for a given combination of parts. They are economical compared to that sheet metal lid. IMO, you would have to have some very special performance goals or perhaps aesthetics to justify the cost of that intake. As a further aside, the OEM LS style of intake is quite prominent in many modern EFI production engines now. It essentially does the same thing as the old 5.0 Ford Mustang EFI intakes but is packaged much better. It’s a good design.



Whether “downdraft”, “side draft”, “Cross Ram”, or whatever the nickname, the true IR intakes are a very different animals and behave quite differently than common plenum intakes. It’s a long discussion but like anything else, the rest of the engine components need to be carefully selected for optimum performance. In the past, IR intakes gained popularity in racing because the isolated runner provides a very strong signal to the booster and correspondingly strong engine response; lot’s of area under the torque curve in a usable rpm range. –Makes for a good road race engine. Engine performance always seems to be compared at peak power numbers but it’s only one reference point. I’ll take most area under the curve for a given rpm range. –Makes a better driver out of me. IR intakes get the wrap for falling on their face at a given rpm but this is only true on a very limited basis. This mostly occurs because they are being applied to larger displacement engines than they can support. These days we’re getting as much as 50% more displacement out SBFs and SBCs than when many of the IR carb systems were introduced. You’re never going to support a 600HP engine with Moon SBC intake and 45 DCOEs or even 50 DCOEs. IR systems require mucho more carburetor capacity than common plenum four barrel carb systems. Injected IR systems (such as Kinsler) that make big power have bores of 2 7/16” (~62mm!). There were never any IR carbs (other than custom built stuff) made to support this power and forget all about it for poked and stroked big blocks.



When EFI is introduced to the discussion, the advantage of booster signal is removed from the IR discussion. However, IR also can make tuning for the subsequent harmonics simpler than common plenum intakes and this can become more important in higher rpm engines. IR is well represented in high rpm mills. The (fuel) timing of EFI can also be of great benefit in managing an IR system. When used with EFI I would contend IR also has a place at the edge of the (high depending upon your view) performance envelope for street and club racing because it can help strike compromise in engine behavior. This comes at a price however in both dollars and tuning time. I often draw skepticism for my view but my retort is always so are the Kinlser and Hilborn people delusional? How about the 4 cylinder motorcycle industry? IR is more expensive so why use it? Are all the Japanese engine designers delusional? -Don’t think so.


A couple of other comments/observations about some of the induction systems mentioned in this thread:


The large common plenum SBF Shelby intake is in the family that many refer to as “Ram Box” intakes. They usually produce excellent high rpm performance albeit in a fairly narrow rpm range. They were good for super speedways in NASCAR but poor for closer road tracks and very poor street induction systems. They are sort of the polar opposite of an IR system; big plenum means very weak booster signal to the carb and low plenum velocity means poor low speed fuel distribution. However, they have an abundance of air/fuel “availability” and thus produce good peak results when properly tuned. Replace the carburetor with a throttle body and properly placed injectors and this intake can actually perform quite well over a much broader range.


The Chrysler “Cross Ram” is a very unique case. It’s really a common plenum carb intake. It obviously has very long runners. In fact, there was actually both a “short” and “long” runner version of that intake as the location of the divider in the runner was changed to affect the runner length and point in the rpm range where Helmholtz resonator affect occurred. Because of the cylinder firing order, this was not a 180 degree intake but it didn’t matter much. This was also not a racing induction system but one that was very purposefully designed to produce low rpm torque for moving a heavy street car.




Best,
Kelly
 
Last edited by a moderator:
John
I agree with you, it is a piece of art. I have a similar manifold and I was just wondering what type of air filters do you run?
There seems to be some debate on performance, throtle responce etc
How do you find yours runs, Can you compare it with an open plenum manifold and a carb?
Cheers
Woody
 
Well, looks like we'll see how well a crossram setup will work - in order to flow what I need to for my engine it's almost a certainty that's the route I'll have to go - there's no other way to package 11''ish runners into the rear without running into massive fitment issues.
 
thanks to all for the hands on experience based comments. i've always loved the look and thought it was a good packaging solution. Now, I know better.

cheers,
 
We installed a cross ram system on my RF 117 we opted for 52mm butterflies which did pose problems with the ram tubes (too big to pass !)

We then introduced an air box and some filters mounted under the rear window. I cant find a shots of the finished filter but the attached photo shows the initial mock up.

Iain
 

Attachments

Kelly

Lifetime Supporter
Well, looks like we'll see how well a crossram setup will work - in order to flow what I need to for my engine it's almost a certainty that's the route I'll have to go - there's no other way to package 11''ish runners into the rear without running into massive fitment issues.
Alex, is the 11"ish intake runner only or centerline distance to valve opening? What RPM range are you looking to make your power?

Best,
Kelly
 
Alex, is the 11"ish intake runner only or centerline distance to valve opening? What RPM range are you looking to make your power?

Best,
Kelly
Shooting for around max rpms of 6500; i want an intake manifold that performs solidly across the board (i.e., doesn't make insane topend power but falls flat on its face downlow)

If anybody can do it, beck can. Can't really compare it with an ITB setup (since it will have a common plenum, hehe) but that engine definately can't take ITB - he said I'd need around 65-70mm for EACH tube, lol.

Just found the pictures of the air filter setup
Did you dyno it? It look slike a nice filtration setup but I'd be curious what happened/didn't happen with the power output.
 

Terry Oxandale

Skinny Man
I looked and didn't see any reference here, but I'm surprised no one has mentioned the old Edelbrock X-F8. I ran one back in the late '70s and '80s with two 390 Holleys. It looked impressive, but it was a pig (heavy and didn't perform well) compared to even an 850 Holley on the Torquer or any other intake.

 

Kelly

Lifetime Supporter
I looked and didn't see any reference here, but I'm surprised no one has mentioned the old Edelbrock X-F8. I ran one back in the late '70s and '80s with two 390 Holleys. It looked impressive, but it was a pig (heavy and didn't perform well) compared to even an 850 Holley on the Torquer or any other intake.
Eddy and MT made a number of those for sbf, sbc, bbf, bbc and others. Many had decent rsults with them. Many did not. That style with two plenums on each bank in a dual plane crank V8 is actually where helmholtz can be the most pronounced and most sensitive. If you weren't cammed for where you came on the intake runner/plenum resonance it could have a profound affect either way. They can be made to perform quite well but as you mentioned, they are a hefty hunk of metal. The FE versions required offest distributor or extensionings.

Best,
Kelly
 
Nil effect on the dyno and i suspect that getting cold air in a controlled manner would have provided a benefit over a mixture of cold & hot from the engine bay

Iain
 


That's my target too. Makes for reliable longer living engine and can still make very good power from 427 CI.

For sure - I don't want to do any heads-off work ever and want the engine to last for at least 100k +. Sure, I could make more with race gas, running solid rollers, revving to 8500, but then I wouldn't be as dead-nuts reliable and maintenance free :D
 
Cross ram manifolds work very well on SBF's.
If anybody is familiar with the V8 Supercar series in Australia they will know that all engines use this setup and produce exceptional power per cubic inch.
 
I have been using the single 4 rambox top on my 65' hipo 289. The engine is equipped with the S3 Cobra Road Race cam used back in the late 60's. It pulls hard from 3000-7000. I am assembling everything that I need for the dual 4 top that I also have since I read in an old Shelby American catalogue that the S3 cam works particularly well with multiple carburetion. Most likely this means with Webers, but webers do not work at all well in Denver! Bundle of Snakes posted the only picture of the linkage that I have ever seen for the dual 4 application. I have researched it and it is an Enderle fuel injection linkage. They still can make one for me, but I need to know the length of the two hex rods that go from the bell crank to the carbs. Can anyone help me?

Thanks!

Walter
 
Hello Walter,
Yes you are correct in identifying the dual linkage as Enderle pieces. As for the length in the photo of the rods; they were just for photo purposes. I have various lengths and would use and or adjust the length as needed. Hex rod stock can be purchased in lengths up to 24 inches long! I have a couple spares as well as a 10/32 LH & RH taps for the rod ends (heim joints). This is the same stock I use for making Weber linkage. As for my Ram Box manifold, unfortunately it sits on the shelf along with the 2 tops and two Holley 390cfm NASCAR type carbs with “Lemans” bowls (long nose). I thought it would look cool. I may use it some day.
Another note on the linkage for the dual four set-up. The driver side carb is designed to be mounted in reverse (backwards). I have seen some guys using the RamBox dual four set-up wrong and they wonder why they are having fuel mixture distribution issues. Drivers side carb needs to be mounted backwards! The clearances on the top are for the carb linkage arms.
Cheers,
~Earl J
 
Top