Real Street Ram 


 Technical Info

The Real Street Ram™ addresses the three major problems that tunnel rams have on street engines.  First, tunnel rams are single plane intakes with a huge plenum.  The large plenum volume reduces signal to the carburetor at low RPM and part throttle.  Second, the two carburetors connected to that large plenum mean that each cylinder is drawing through four venturis at part throttle – this reduces venturi velocity, giving you poor atomization and fuel metering.  Third, the positioning of the venturis above particular runners means that fuel distribution is poor at part throttle.  When only the primaries are open, the runners directly below the primaries get much more fuel than the others.  All these problems lead tuners to apply band-aids like running richer jetting to get the lean cylinders approximately right (at the cost of further richening the already too-rich cylinders), and using huge amounts of initial timing to light the lean and poorly atomized mixture.

In the Real Street Ram™, all these problem areas are eliminated.  Instead of one huge plenum, there are four very small plenums.  When there is an induction event for a cylinder, it creates a crisp pulse of air through that plenum, giving a strong signal to the carburetor.  With the separate plenums, each cylinder draws from a single venturi at part throttle.  The booster gets high peak-speed airflow, which lets it correctly meter fuel.  Finally, the plenums are specially shaped to force fuel to the center of the plenum and then allow it to distribute evenly between the two runners connected to it.  Our carburetors are specifically engineered to work with the unique dynamics of feeding a pair of cylinders which are not evenly spaced in the firing order.  In fact, the rear pair of cylinders on the driver’s side fire only 90 crank degrees apart in both the small-block Chevy and Ford!  The Real Street Ram™ is a complete, engineered package that gives you the head-turning look of a tunnel ram, and backs it up with real-world performance that beats the best dual planes.  We've done hundreds, if not thousands, of dyno pulls developing the custom tops and dialing in carburetor calibration, so you can bolt on the manifold, set the idle, and enjoy driving!   When you put a Real Street Ram™ on your car, you can keep everything else the same and just enjoy the extra performance.  Stock converter?  No problem.  Highway-friendly gears?  Great.  Exhaust manifolds?  Yes - enjoy your frame clearance and no leaks.  Stock or mild cam?  You bet.  Build yourself a long-legged cruiser, install a Real Street Ram™, and enjoy gas mileage, smooth running at overdrive RPM, and everything else you get now with a dual plane and single four-barrel.  But you’ll also be enjoying dual quads on a tunnel ram!  

The Real Street Ram™ is designed to work with stock to mild street engines up to 450HP.  If you have a favorite combination that works, add this into the mix and give it that unmistakable street rod look and tire-shredding torque!    

                                Real Street Ram – Give your ride a Pair that Really Works!   

                            The Real Street Ram is protected under US Patent 8733312.    

Above is a cross-section showing the structure that pushes the fuel to the center of the plenum and then allows it to distribute evenly between the cylinders.

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The graph above compares torque for the Real Street Ram™ against a popular high-performance idle-5500RPM dual plane, on a bone stock Goodwrench 350 engine.  The Real Street Ram™ produces amazing torque from the low-compression mill.  We've also run on an 11:1 compression 350 with a .570 lift roller cam and ported Corvette heads.  That engine made 460HP peak with an air gap style dual plane.  The Real Street Ram™ made less peak power on that engine at 440HP, but produced superior power everywhere below 4000RPM.  Our third test setup is on our 1971 El Camino shop truck with a smog-headed low compression 350, a small aftermarket cam, TH350 wtih stock converter, and 3.55 gears.  We have not put the truck on the chassis dyno, but the driving impression is fantastic.  At 5000 feet of altitude, the Elco will spin the tires by just applying enough throttle to load the converter, and then snapping the throttle open while releasing the brake.  Expect your idle to be a little choppier with the Real Street Ram™.  Things get funky for the idle circuitry in the carburetor when the vacuum in the plenums varies so much during the engine cycle, due to the uneven firing in each plenum.  Everything smooths out and pulls very hard as soon as you open the throttle, even at ridiculously low RPM.  If you have vacuum operated accessories, you should use a vacuum canister with the Real Street Ram™.  There is not a problem with reduced vacuum, but there is no good way to put a large fitting and vacuum hose in place to run a brake booster.  We recommend connecting the large vacuum port on the back of the rear carburetor to a vacuum canister, and then running a large fitting from the canister to your booster.  Note that large body HEI distributors will not fit with the tunnel ram base.  You must use a small-body distributor like an old points distributor size.  Summit sells some nice ones just under $200.

In a race application the only throttle positions used are idle and wide open, but on the street part throttle matters.  You want to be able to cruise smoothly at low RPM, and still get a huge kick of torque if you snap the throttle open.  You also want smooth response to small adjustments of the throttle – what engineers call “tip-in”.  In other words, you want your engine to be super responsive under all conditions.  Now you can have all that and also have a tall vertical tunnel ram that screams “Power!” - and delivers. In the past if you wanted to run a tunnel ram on the street and have it actually work as intended you had to build the rest of the car around it and forget street manners.  You needed a 3500-stall torque converter for an automatic, deep rear end gears, a big cam to make power at high RPM where the tunnel ram works, and headers and the rest of the exhaust set up for high RPM too.  This can all be done, but it makes the car act like a race car.  Terrible gas mileage, high RPM all the time, crap for low-end torque.  Not a pleasant car to drive very far.  Fun for blasting around at high speed, but you don’t want to drive it on a long cruise.  The other way that hot rodders go with the tunnel ram is just to jam it on the car and see what happens.  What happens is not very good.  If you haven’t set up everything else on the car to work with the tunnel ram, you end up with a real turd.  You lost your low end, and the tunnel ram doesn’t start to get happy until the rest of the combination is getting out of its RPM range.  People who are reasonably happy with a conventional tunnel ram on the street have either built the rest of the car around it or have so much displacement in their engine that killing off a chunk of bottom end torque is a non-issue.

Below is a graph comparing the RSR to an RPM air-gap manifold on a 365HP 355-inch SBC.  The RSR shows a big fun factor at the RPM you actually drive at on the street.  +31lb-ft @ 2800RPM!  Over 20lb-ft increase from 2000RPM to 3200RPM.  Stronger than the gold standard dual plane for mild street engine performance all the way through to 5200RPM.  We lost a little vs. the RPM from 5400 through 5800 RPM, but average torque from 2000 through 5800RPM was +11lb-ft in favor of the RSR.

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