More about a cross ram - Team Camaro Tech
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post #1 of 7 (permalink) Old Jun 14th, 01, 05:56 PM Thread Starter
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What is the advantage of using a cross ram intake? How much more power would it make on a 350 over using an edelbrock preformer rpm intake and 600 carb? I know they look cool but it must be dificult to get both carbs tuned and working properly.

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69 Camaro RS, 355ci mild cam, Preformer rpm intake, edelbrock 600 carb, 350 turbo w/ shift kit 2500 stall, 10 bolt 2.73 any more questions ask
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post #2 of 7 (permalink) Old Jun 14th, 01, 09:23 PM
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You should post this question in the "engine and drivetrain section", or the "performance" section.
I had a friend tell me he tried both on the dyno and the crossram gave about 20 to 25 hp more than a single four Z/28 manifold above 4000 rpm.
David

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post #3 of 7 (permalink) Old Jun 18th, 01, 05:53 AM
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Cross-rams are junk on a street-driven car. They make great power over 4000 rpm, but are nearly impossible to tune for throttle response and driveability under normal street driving conditions due to the huge ports, open plenum, low air velocity, and lousy air/fuel distribution at low rpm. People forget that dyno pulls only last 5-10 seconds, and are at wide-open throttle, with no thought whatsoever given to what a street-driven engine needs. Dyno numbers can be impressive, but street driveability is another matter entirely. They don't run anywhere near as well on the strip as a single 4-barrel either due to their poor power under 3500-4000. Looks great in a magazine article or on the show field, but that's about all.

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post #4 of 7 (permalink) Old Jun 18th, 01, 06:59 AM
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Aside from all the other problems on a street car they get horrid gas mileage and will not run when they are cold. I think that could be a real problem in Mi.

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post #5 of 7 (permalink) Old Jun 18th, 01, 08:53 AM
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Back in '69 a local dealer installed the cross ram setup and track cam in a stock 302 Z/28 with 3:73 gears. I had an opportunity to drive the car. Under 4000 the car was very slow. By 4500 it was starting to make power. A magazine road test of one showed low 15s at 100mph or better. With that mph it is obvious that the car was making up for a lot of time on the top end. For street driving you would want nothing less than 4:10 - 4:56 gears. Definitely not streetable and very expensive. The car, as set up, was more expensive than a COPO car which did perform. The choice was simple for me.
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post #6 of 7 (permalink) Old Jun 20th, 01, 07:21 AM
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69Camaroracer,
I'll add my two cents worth. You can't just add a crossram and expect performance gains to your engine. As you can tell from some of the response here a lot of guys bolt them on because they look cool and are disappointed in their now poor performance. That's why Chevy ground a special cam for Penske and Donahue to use with their crossram. Chevy recomends you run a minimum of 12:1 compression with the crossram cam due to the overlap profile. You also need the correct gears to keep your vehicle in it's new power band, which is going to be above 4000 to 4500 rpm. Using 3.73 gears with a cross ram you probably won't be happy. Smokey Yunick said if you can get a crossram set up "PROPERLY" there is simply nothing that will run with it. He dedicated a lot of his time to the deveolpment of these manifolds. Problem is most people forget the properly part. They want the look and forget the rest of it. I've driven stock 302's and in my opinion these are not what most people consider good street motors today, but I love them. If they hook up below 4000 when you launch them not much happens. But if you hook up above 4500 to 5000 and keep pulling watch out! I'll never forget the look on this guys face when I lined up against him in my 302 69 Z and reved the motor to 5500, popped the clutch and mashed the throttle to the floor. That's what you did to get the 302 to pull, he was driving a 455 70 Firebird, so he was probably redlining where I had to leave the line! It broke his heart to hear he'd been beaten by a motor that had 1/3 less cubes than his. So think about what you really want. If you decide you want to run a crossram, go for the entire package and stick with a short stroke motor, I don't think a 350 is a good choice for the high rpm range these were designed for. Don't get sore about this, the 350 is a wonderful engine, just a little too much stroke for the high winding you'll need to see the benefits of the crossram. But I like high reving, rough idling, steep geared cars.
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post #7 of 7 (permalink) Old Jun 20th, 01, 09:49 AM
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SY1 explained it exactly right...............
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