zoomies vs step headers
 

how much if any et loss whould i see if i use 2 1/4 zoomies vs a 2 3/8 stepped to 2 1/2 tube into a 4 1/2 merge collector on my 582 bbc? i've used zoomies on my kb 526 blown alky(1800 - 2000 hp oddy motor)but never on a na motor. love the looks and sound of zoomies but would like imput thanks jeff

are you going to continue to use forced induction on gas? is na non alcoholic or naturally aspirated? not clear on the abrv.

more than likly i'll be using a terminator(alky)

So naturally aspirated. Well with zoomies on a non blown application will make your engine be the poorest performer at the track. The engine will be confused below 4500 rpm or so then clean out and act ok for a few thousand rpm then revert at another rpm higher again. Zoomies provide no help to the incoming air charge to the head and will not give the benefit of sharing exhaust pulses to aid the scavenging effect for the next cycle that a good working collector will. If the length is short it will also burn the hell out of your exhaust valves if you are persistant in trying to tune it that way.
A step pipe or non step, 4 in to one collector type is the only proven set up or a few variations of that for naturally aspirated 4 cycle engines.

thank you great advice i'll stick with my steps. jeff

I know it's apples vs oranges but we had a blown small block in a door car with zoomies, went to a 434" stacks injected engine both on alcohol and tried the zoomies for a couple weekends. I too love the sound of zoomies. O'k changed to 2" 34" primaries with 3 1/2 collector, picked up .15 the first time out and a little more after a little tuning, the car actually needed less fuel and ran faster with the headers.

Zip.

i have to be realistic and use the steps. you really love the stack injection.i knew one guy that ran them couldnt figure them out he went to a hat and ran flawless 8.30's at 161 at 2400 lb 67 camaro.i don't say that to get you pissed it's the only time i ever see stacks.i see you can get systems pretty good pricing what whould you say they have to offer over the hat or the terminator.i do like the look of the un even stack set up. jeff

I've ran my first supercharged car in 1964, i've also been tuning stacks since about the same time. I really don't know how much HP change there is between stacks and a hat or between stacks and a toilet bowl, i think they all can run good. I have a 4.100 toilet on my 377" Malibu, i have a friend that has a 4.100 bowl on his 55 shoebox weighing 2650 lbs with a 396" sm/blk that runs low 5.60's. When i first built my 377" motor we put it in my friends dragster with stacks on it. It ran 5.15 & 8.23 @ 158mph at Memphis. The best i can run in my Malibu weighing 3250lbs is 6.52 and 10.59 @ memphis. So i guess all to a persons liking, but stacks are no harder to run/tune than a toilet bowl or a hat, and also can be dead on. Ref. Jimmy Smith here on RJ, runs a 350" flattop motor with stacks, he runs the 7.00 class with a long petal stop screw, and the 6.50 class wide open in a 3,000lb Camero, and shoots 4.0's lights all nite long.

JMO

Zip.

sounds like i should look into them more.do some research thanks again jeff

I think if your going to have to buy new headers, take a look at these brands.
http://www.racingjunk.com/category/1...ollectors.html

http://www.racingjunk.com/category/1...swept-BBC.html

Both worth ET over any other header, fab shop also makes downswepts.

i have a nice set of hooker steps with merge collectors came off a prostock car so i had to change the flanges from the drce bolt pattern.also have set of zoomies but after reading everybodys commets i think they are NOT the way to go. jeff

What if you ran a smaller zoomie like a 2" or 2 1/8"?

Or maybe even a stepped pipe,start with a 2 1/8" into a 2 1/4"?

This is for nofear69, There would be virtually no difference to the engine reguarding primary diameter with zoomies on a naturally aspirated engine. simply put zoomies are zoomies, diameter be damned. As for the tiny 2.125 primarys on a 582 racing engine with a step to any diameter would work ok on a 500 to maybe 600 horsepower hyd cam mild engine in a heavy street car. That small of pipe may not even clear the entire exhaust port on most racing heads now a days for a engine this large. The 582 will require a 2.25" primary in most any power level baring the previous example. The 4 in to one collector helps scavenge the spent gasses out to help aid in initiating the incoming air charge. zoomies do nothing for a naturally aspirated engine but make a cool sound according to some, or so I am learning. I hope this additional explanation helps my earlier entry make sense.

I was considering putting zoomies on my non blown alcohol injected sbc altered just for the sound but I probably won't. There isn't much info. out there for this application. I guess its all experimental but they should be left for the blower cars.

This guy just put these up forsale Ad #1452722.

i hope the steps i have are big enough for my 582 i'll be running 1/8 mostly but i wounder what a 2 1/2 primary with a 5 inch merge collector would act like i bet too big down low(in the 1/8)and great at the big end(in the 1/4)the motor seamed real responsive with a 2 1/4 header on it last year BUT never made it to a 1/4 track or had a chance to put the steps on it to see the difference. jeff

No matter what head you are using be it 12 degree pro stock or 24 degree brodix type stuff, your engine will never like 2.5" primarys at the head under any circumstances guarantied. The 2.25 primarys stepped to 2.375 may be nice for your set up and more forgiving than it would be with 2.373 on the head with 2.5 to collector and unless you shoot tons of smack in your engine, the 5" collector is way over sized as well. There are more detramental effects to over sizing your pipes than under sizing. Remember the step is intended to enhance the top end horsepower for higher rpm usage and will not increase the bottom end power numbers, in fact they are lower than what a single diameter primary will produce.
Stay with what you have been using, The larger headder will not assure you more performance on the top in all instances.

i'll be trying my steps they are 2.375 stepped to 2 1/2 with a 4 1/2 merge collector.do you think a straight 2 1/4 would work just as good? also how do the comp guys make zoomies work on the fed with 406,s and stack injection? just curious thanks jeff

The 2.25" single dimension primary will not behave similar to a step pipe of any size. Your previous entry noted that you were using a 2.25 primary with good results, and that was the basis on my recommending that you use that size pipe. In that same entry concerning the 2.25" pipe, you indicated that you might try a 2.5" primary which is too big for anything I have ever seen that was using carb's and nature to fill the engine. When you look at all the different combinations that people try to run and notice that you have a combination now and then that seems to defy physics by using an arrangement that should not work well, like the zoomies on the alcohol car using Nature to fill it, (No blower). There is more to the picture than you could see, or there were huge concessions made in the torque department and engine harmony for a theoretical perfect top end tune-up. Let me know if you ever figure out the answer to that one, I am sure it would be very interesting to hear the reasoning. I have had no success nor have I heard of any one having any luck with that configuration on a naturally aspirated engine.
This will be my last entry on this thread, I hope you find this information entertaining or helpful, good luck