FrontEngineDragsters.Org Forum
Drag Racing Discussions => Front Engine Dragsters => Topic started by: dgrossmann44 on November 21, 2017, 12:52:51 PM
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Is a vac pump the only option when running zoomies .
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my experience is a NA engine will pick up 20-25 HP with a vacuum pump on a a good sealed engine,because of better ring seal, shoot for 15-20 " of vacuum.
If a racer is racing brackets, or dial-in's, and doesn't need that 20 hp then don't bother with more pumps, hoses, belts, etc.
If a racer is not running water in the engine, start using water, I have seen that pick-up 15-20 hp, because of better cyclinder wall vibrations = better ring seal besides better temp control.
Just my 2 cents.
Jon
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Jon , Your two cents are well worth it Thank You
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Was just about to build puke tank for Crank case vent system and had someone call and ask if I wanted his vacuum pump setup. Hey if its worth 20 hp I'll give it a try.Heck I have done lot more for less.LOL
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There are special rear main seals and stuff for high vacuum engines--you need to pay attention to gaskets and sealing--unit with vacuum pump will not leak a drop but can pull gaskets in --valve cover gaskets need to be highest quality like the two layer with shim in middle etc-- Higher vacuum is not better like Hayden mentioned is pretty good amount valve stem seals become very important--vacuum too high actually can pull oil off and out of stems and cause lots of wear fast so...it takes some study not just bolt on and get lots o rewards do your homework and consult your engine builder what the real deal is it allows ring packages that you could not run otherwise--Lots to it
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Yes I agree with Dave. Lots to it. And...watch what happens to me in the shut down area. This is what happens when you get a midplate leak and your vac pump exhaust tank is too small. xxxx thing tried to hurt me
Wait for it
https://photos.app.goo.gl/Xqn0u6thQR2kQVUA3
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Might want to look at this site, towards the bottom of the page. A boat racer attached a pan evac system on a zoomie pipe and was able to pull 5" of vacuum. It's not the results of a vacuum pump but it's more than just a puke tank or breathers.
http://www.performanceboats.com/gn7-dyno/52702-header-evac-zoomies.html
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More info I got from Jon.
I don't have a better ET number for you, because my partner in our GoodGuys/ Heritage Jrfuel car did not run a vacuum pump on his old engine, 406 ci all iron SBC [ non-raised runner 23°] , but when I built
my raised runner 23° all iron engine I ran the vacuum pump. Old engine ran the best of 7.36, new engine 403 ci ran the best of 6.99. 189 mph.
If you are running brackets, it's whole lot of work and effort to chase that 20hp. it works because of better ring seal, with low tension rings, plus the engine needs to be vary well sealed, a constant goal for us.
Our vacuum, measured with my RacrPak computer, ranges between 5-16" but mostly 10". The 20-25 hp claim was from comp engine builders that have dyno's. All of our alky burning JF teams run vacuum pumps , but a few also run dry sumps which give them more vacuum, 12-22". BTW with any vacuum over 20" you must increase the wrist pin clearance , because all that vacuum pulls oil away from the wrist pins. I had one SBC engine with a small hole drilled up the center of the alum rods to get oil to the wrist pins, from the rod bearings. That's one of the reasons I posted if you race brackets, it may not be worth all the work and money. Like besides getting low tension rings, O Ring groove valve cover adapters, expensive silicon seal, and use lots of it, around the intake gaskets, mag drive hole, like any gasket surface . It got even tricker with our Gene Adams built early iron Hemi because it didn't have as much vacuum as my SBC, so we put a smoke machine hooked to the oil pan and we had smoke everywhere, like around the rear main seal, because no one seems to make a double lip seal, we even had smoke comming out the exhaust bolt holes. It took us a while to figure the copper head gasket was not sealed good enough around the water holes, thats how the smoke got in the water jackets and out the zoomie bolt holes.
Like I said it's allot of work and maintance to chase after vacuum, like everytime we warm the engine up in the pits we disconnect the hose from the valve cover [ because trying to keep the wrist pins in good shape] we spray some brake clean in the pump, and aim the hose going into the puke tank into a oil drain pan, just to clean the pump, they work better when clean of oil.
I hope this helps, could you add this post to FED.org. I think this will only show up in messages.
Good Luck with your project, call if you would like more info, 805-444-4489
Jon Hansen, Hayden Wheels, and founder of Jr Fuel Dragster Association
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There are special rear main seals and stuff for high vacuum engines--you need to pay attention to gaskets and sealing--unit with vacuum pump will not leak a drop but can pull gaskets in --valve cover gaskets need to be highest quality like the two layer with shim in middle etc-- Higher vacuum is not better like Hayden mentioned is pretty good amount valve stem seals become very important--vacuum too high actually can pull oil off and out of stems and cause lots of wear fast so...it takes some study not just bolt on and get lots o rewards do your homework and consult your engine builder what the real deal is it allows ring packages that you could not run otherwise--Lots to it
I asked my engine builder after some research .I said stay around 15" no reason pushing for more on bracket engine. LOL
I guess lot more folks having engine built than I would have thought. When I started racing in 80's 1 in 10 bought a engine. Seems now days its 1 in 10 build their own. Just takes the heart out of t IMO.
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I know that evac pump kits have been discussed before, but I can't seem to find in the NHRA rulebook where puke tanks are mandated for specific FEDs. I have a 190" alky FED (no blower) with Ron's injection on a 7.50 cert chassis and 428 Pontiac. If it isn't required to have the 2 hoses off the valve covers going into a gallon sized puke tank, I will just run a evac pump off one valve cover and a breather tank. I hope to run NE3 or NE2 at some point. Any help with the rules here will be appreciated.