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Hemi Question..


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Hi guys,

In my ongoing Question and Answer interest, I'd like to ask what these hoses are for (marked red line)?

post-13335-0-67035200-1436213881_thumb.j

I've seen them often in my Internet travels, but again I don't know.

This series of questions all pertain to my new project.

Thanks for looking. More thanks for info.

Michael

PS: Geez, I've done better. The thick looking rubber insulated hose from head to ...wherever is what I'm focusing on.

Edited by 10thumbs
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OK. Does the evap system go back to the fuel tank? Where or to what do the front ends of the hoses go in to. Would there be some kind of connection down lower, maybe from the block somewhere?

Thanks guys.

Michael

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Crankcase evaporated system

Sounds to me like a little confusion in terms there. An evaporative system on street-driven cars is typically part of the emission control system, having to do specifically with preventing fuel vapors from entering the atmosphere.

A crankcase-ventilation (breather) system has an entirely different function. The hot, whirling parts inside any engine, and combustion gasses from ring-blowby, produce a constant oily mist at positive pressure (over atmospheric). In a street car, the PCV (positive crankcase ventilation) system handles it, venting the mist-laden vapors back into the intake manifold, and they're subsequently burned by the engine. The problem is exacerbated by a supercharged engine with higher combustion-chamber pressures and more ring blowby.

Drag cars of times past (really, any high-performance application) didn't (and still don't) want the oily mist to be sucked into the engine's induction system (where it would interfere with accurate tuning) so they simply vented the oily vapor out through the rectangular 'breathers' sticking up from the valve covers.

DSCN7274.jpg

Later on, racers found they could pick up a little extra power by actively sucking the positive-pressure out of the crankcase with a pump. Of course, the air that was sucked out was laden with oil mist too. It had to go somewhere, and vented catch-tanks were provided to hold it, instead of just dumping it on the track.

If you notice in this shot, the large hoses for the crankcase ventilation system, similar to the ones on the OP photo, run from the general location of the valve-cover breathers on the older engine shown above.

BR_RickRogers_02.jpg

This is a relatively common pump-driven crankcase evacuation system, showing the pump, hoses, and vented catch-can / oil-separator.

15Deg427SBC.jpg

There's been endless discussion about the effects of evacuating the crankcase on drag engines, how much vacuum to run, electric or mechanical pumps, plumbing layout, catch-can (oil-separator) design, etc.

As I said above, I'm not currently familiar with the big-hose systems shown in the photos.

Surely someone who is will pipe in and let us know all about the plumbing at the lower end.

Edited by Ace-Garageguy
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Bill, great info, many thanks. So, with this info I just did a search and up came some pics with what looks like the place where the hoses are going.

They look like they're going into the frame rails on each side! I can't see yet if any other hardware is attached. I'll look further and report.

Michael

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It is the frame!

Front left side, look;

post-13335-0-78779600-1436282748_thumb.j

This is on an 8000hp Top Fuel motor, article from HotRod Mag.

Interesting!

I guess that's some kind of filter mounted atop the frame rail, and a cotter key to easily get at the thing? Just a guess.

Edited by 10thumbs
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It is the frame!

Interesting!

I guess that's some kind of filter mounted atop the frame rail, and a cotter key to easily get at the thing? Just a guess.

I doubt it's allowing the oil to collect IN the frame. I would think that they are dead ended and just cottered to the frame to keep them from moving. Afterward they pull the pins, remove a cap of some sort and drain any oil that's accumulated.

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My guess...and this is only a guess...is that there's SO MUCH blowby on an 8000HP engine, the volume of the previously shown oil-separators just isn't enough to cope.

Any venting system is going to have to be vented to the atmosphere somewhere. Note the air filter affixed to the top of the catch can in the pump-driven system above. This lets cleaned air blow OUT, after it's been sucked out of the crankcase by the pump.

I'm guessing the frame rails have a similar filter attached to them somewhere, allowing clean pressurized air to vent to the atmosphere, and the rails themselves act as the separator / catch-can, probably drained after a run or two.

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It seemed to me, at a first glance, the Top Fuel motor frame area in question showed some kind of corrosion. But then I doubt such a car would have anything corroded on it. Maybe the hose is removed after every run and there's some leakage or dripping involved.

This blowby, would it be of a thicker nature or runny/oily? I suppose the oil is changed very often so it shouldn't be too dark, but then a motor like this is not a normal type.

I'll do further searching.

Michael

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I like these threads because the more we understand about what we are building, the better and more interesting our models will be - great stuff here.

It's part of the crankcase ventilation system - the hose connects to the valve cover - there are some baffles that kind of separate oil from crankcase vapors in the piece on the valve cover where the hose attaches - the other end connects to the upper frame rail which is a convenient piece of tubing to carry what is left to a large vented tank aft of the roll cage on a funny car, aft of the engine on a dragster. No pump As mentioned above, crankcase pressure on a supercharged nitro hemi is enough to ventilate the engine to the tank. I imagine between round maintenance includes draining and cleaning the tank. The hoses usually have some sort of quick connector so parts can be disconnected easily for service.

Pumps are used on normally aspirated drag racing engines to create a vacuum in the crankcase. Lower crankcase pressure means less internal resistance on the bottom of the pistons - lower pumping losses equals more horsepower.

Edited by Muncie
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Hi Gene, yeah, this is fun! My next Hemi will have this system for sure.

Hi Steve, thanks for the info. I couldn't imagine the junk running through the frame rails because of safety reasons. Do you have a link, or a pic that shows one of these collecting tanks?

Thanks guys.

Michael

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sorry Michael, I don't have picture or a link.

The catch tank really varies with the vintage of the car. The Monogram funny car kits from the mid '80's have a good tank behind the roll cage for what was used then - the tanks have become larger as time and engine technology have progressed. Current top fuel cars have a tnk that looks like a five gallon paint bucket near the rear axle - plenty of room for a Jegs or Summit decal...

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Thank you Steve. I'll continue searching this topic and I'm sure some pics will show up.

Guys, if you're interested, here's a good read; http://www.jalopyjournal.com/forum/threads/positive-crankcase-ventilation-101-tech.31741/

Interesting, even street motors will blow up without an "evap system". The oil pan explodes. Then fire. This happens at the drag strip too.

Michael

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Interesting, even street motors will blow up without an "evap system". The oil pan explodes. Then fire. This happens at the drag strip too.

Michael

Please...evac...not evap. Evap is short for "evaporative emission control", an entirely different concept. See post 5.

Evac is short for "crankase evacuation system".

While these are often confused, they are two different things entirely.

Edited by Ace-Garageguy
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Oh my. Google corrected me too. I feel stupid. It's OK though. I've done worse.

This crankcase evacuation deal will become a standard now for my upcoming motor builds. The new motor block and oil pan have been cast in metal already, and I found some heads and valve covers big enough for all of the junk coming out of them. Plug wires and now the e-VAC hardware. I think I need a longer frame though.

I'll search for inconspicuous small tanks on race cars now.

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So far, I found this;

"all top fuel funny cars run it to the rails and have a puke tank tied out back and you drain it each round usually get a little oil and fuel unless it hurts itself and they also have drains in the front behind the weight bar drain the rails once a weekend top fuel cars on the other hand are tied directly to the puke tank have never had and issue with corrosion on one worked for densham and before we went to new grant chassis at mid point last year old pluger chassis had over 400 runs on it"

Well, grammar is another topic. I'm happy with the insight.

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Pictures of a funny car catch tank in its natural environment are rare. Most available funny car pictures are in competition or with the body down. Any pictures with the body up are just the front of the chassis with the nitro hemi...

The catch tanks will be specific to a certain car or time period.

Here are some places that may be useful for finding vintage funny car tech

Vintage funny car restorations - here's one - http://www.ramchargersfunnycar.com/index.html

The forums on the classic funny car board - http://classicfunnycarboard.com/

search terms - funny car catch tank, puke tank

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Hi Steve,

Thanks for the links, I'll weed through those for sure. Piece by piece things are coming together, here a pic and there some info, it's good stuff. I'm kind of hooked now on wanting to get the details right for my next project.

I've seen now and then evac hoses but never really gave much thought to them as they were on motors that I wasn't interested in building. Things are different now, and here's a look at a simple setup that can easily be made for our models;

post-13335-0-75019500-1436544466_thumb.j

This has proven to be an interesting search, lots of good articles to read and I'll continue searching.

Michael

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I wouldn't worry too much about corrosion inside the chassis tubes, there is enough oil vapor in the crank case fumes to prevent that from ever happening.

The "puke" tanks got larger after the oil down penalty rules we have today came some years ago, they have to contain all oil from the engine if it blows up so the puke tanks got larger and more efficient, and the addition of full cover belly pans with capacity to contain all oil from the engine has minimized the oil spillage on the track....but sometimes it happens anyway.

Here are a couple of pictures of modern "puke" tanks.

First for a Nitro Funny Car

post-363-0-23768300-1436571406_thumb.jpg

And a Top Fuel Dragster.

post-363-0-05896100-1436570846_thumb.jpg

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Good photos Hakan, many thanks. They look quite heavy duty!

In the meantime I could imagine there being a tube within the frame tube for handling this duty of evacuation. The tanks are much larger than I suspected, now I have a specific look to watch out for when searching.

By the way, those are some fat slicks on the first photo! Amazing to think the power available to make them smoke during a run.

Thanks Hakan, and greetings to you crazy Scandinavian car nuts. The 1st pic is maybe of a car from the midsummer cruise night?

Guys, those fellows way up north are wild! They close streets downtown so they can race!

Michael

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