Is the Tuba huge for a reason?

[max49]

It goes into a little 4" opening. Does that huge swelling serve any kind of performance reason, like an expansion chamber on a high performance 2 cycle engine?
It's huge and ugly, blocks precious airflow because its right in front of the passenger side fan and it looks dumb and takes up alot of room.
I took mine off but haven't driven it since.
I just wondered if that "intake air" expansion chamber served any purpose.
I'm also considering cutting it in half right where the mounting band goes. At least then it would be half as big and not right in front of the fan. That would replace the 4" ducting I put in.
I really can't see the need or performance gain I would get from putting a whole new air filter box in like some have done, but I don't like the tubba.

[iRV4FUN]

Originally Posted by max49

I really can't see the need or performance gain I would get from putting a whole new air filter box in like some have done, but I don't like the tubba.

Max, I think it’s a waste of time trying to fix stupid. Most everyone on this forum has swapped it out. I thought I was the last person on the planet that still has the ugly inefficient WHCC Tuba in place. Some of those GM or WHCC design people should have had their names proudly engraved on the side of these brain storm items. Then I’d know who to send their stupid drug induced parts back too.

Once the Tuba Designer gave the part to another braineac they placed it in front of the radiator for maximum deficiency. So there it is -- in front on my radiator blocking an already fresh air starved coolant system. And when my rig comes to a stop or is cruising low speed through the subdivision it sucks up a lot of engine heat. I know this because my laptop program can track the C.A.I. temps.

So dumping the Tuba into a landfill and installing a real Cold Air intake may make some real sense. Reading another forum it was said that the 8.1L “temperature sensor in the intake air stream flow pulls out timing at 86* F.” If this is true, then I believe it’s important -- for maximum timing advance -- to insure that cooler outside air is drawn into the system at all times. My stock filter is due for a change and I’m going to take the tuba plunge. It will draw air either via a scoop or from behind the pass headlight so that higher temperatures under hood will not air into the intake. Just need to avoid water intake…


By the time I make all these mods & upgrades I’ll either be in the poor house or a psyc ward!

[M&EM]

Originally Posted by max49

I'm also considering cutting it in half right where the mounting band goes. At least then it would be half as big and not right in front of the fan. That would replace the 4" ducting I put in.
I really can't see the need or performance gain I would get from putting a whole new air filter box in like some have done, but I don't like the tubba.

Max BTDT.
I cut my tuba up and reattached screen opening to lower half. Left the water drain in. Opening faces the grill. Been in for more than three years now. Been thru some heavy rains with it and not seen any problems..yet.

Basically, I cut out the 90 degree bend and re attached the screened tuba. flair forward facing and reflanged and pop riveted. Then sealed with polyurethane roofing sealant from HD





This open end was sealed off with a piece of diamond plate aluminum pop riveted and sealed as in the above.





Used same mounting band as before. Not as ugly.



Any water that gets in has the same escape route as the original.



Its a little noisier.

Hope this inspires.

Marty

[wa8yxm]

I can think of one reason for the shape of the Tuba, and in a manner of speaking it does have to do with air flow.

The engine is called a "Vortex" and ,, well that shape on the air intake would tend to encourage that particular air flow pattern (Vortex or funnel) Of course the placement of the air filter would break up that flow.. but .. What do I know.

I suspect a better design is quite possible.

[dieselclacker]

I think the shape and length of the intake horn is for noise suppression of intake air.

Dieselclacker

[VanDiemen23]

like dieselclacker said - it's a resonator to kill certain frequencies that produce intake howl.

Almost all modern cars have 'em - usually some odd shaped blivet between the MAS and the throttle body. CAD and flow modeling makes it possible to gin up something that fits in some otherwise odd-shaped unused space and still do the job.

[M&EM]

Originally Posted by dieselclacker

I think the shape and length of the intake horn is for noise suppression of intake air.

Dieselclacker

And maybe to distill out moisture on the inside surfaces that eventually drain out thru the fnipple like thingy at the low point.

Marty

["007"]

I would just bite the bullet and remove the TUBA and install a CAI.
No problems with water getting into a air filter box or the MDF.



The little rubber hanging thing never worked for draining rain water on my coach with the water intake through horn.
More cooling with it removed and a hummer of a Motor Home if you have the duel exhausts.

[DriVer]

Originally Posted by "007"

I would just bite the bullet and remove the TUBA and install a CAI.

Roger ..... The picture is moving all over the place .... I have to get my Dramamine!

[max49]

Thanks for the tips, advice and especially the pictures. I always hesitate to make irreversible changes but I'm beginning to realize, I must have been one of last ones to get rid of the tuba.
So why do they call it a CAI (cold air intake?) Is that a special brand name? Where does it get the "Cold" air from? On my SG , I sometimes use that intake air temp gauge just to know the outside temp. Always seemed close , to me.
So , is putting the air intake closer to the grill opening a little better so it may be a just a little cooler? Is that how they get the "Cold Air Intake" name, or am I still missing something?

["007"]

Max did you ever remove those metal panels off the frame rails to open up for ventilation around your engine?
I believe with them on both sides of your engine its just building up the heat in that area.
Your engine is boxed in and hot air gets trapped in around the rear spark plug wires and this is the result.



You can see one of the panels on right hand side of top picture.
The panels are pointed out in this post also.

This was my suggestion at that time.

[iRV4FUN]

I have done alot to force more air into the engine compartment and cool pack. There's a big separate opening below the grill area that , as designed would just send air under the MH. I put a sheet of aluminum made from a "Road Construction" sign , angled to force all that air straight in to the cool pack. Even the mechanics that changed the engine said that was a good idea and they liked my blower ducting on the Port side of the engine. However, it was not enough to save the old engine, but they even said, 'it can't hurt'.
-- Previously Posted by Max

If you're moving this seems like a good idea. Seems like alot of people have found this to be a solution to stop the loss of air downward and under the frame.

But, what about when the unit is at a stand still or in slow go traffic situations? Isn't this a restrictor of air flow in no or slow go situations?

UPS man just delivered my two Attwood 4" In-Line Bilge Blowers (230 CFM each). Plan to put two air scoops under the pannel that Max describes above for passive air / bilge blowers that will empty at the front of the air dam and hope side dam pannels will help direct fresh cool air flow over enitre engine. If at the very least I should be able to cool the doghouse down faster with the blowers postioned in front of the doghouse.

[dieselclacker]

iRV4FUN,

You might consider removing, at least temporarily, those side panels along side your engine as suggested by 007 to Max 49 in the above post. Seems to me like you guys may be missing out on a lot of wheel opening air to the sides of your engines. And, like 007 is saying, you may just be trapping heated air along side the engine by using these shields. Looks like it would be pretty easy to remove them, and certainly would be worth a try to see if it would help with the plug wire problem. If it doesn't help, re-install them. No harm, no foul. I have a W-22 with no plug wire problems, and from the front wheel openings, I can see the whole side of the engine on both sides of the motorhome with no shields or obstructions at all. Anyway, just a suggestion.

Dieselclacker

[max49]

Originally Posted by iRV4FUN

I have done alot to force more air into the engine compartment and cool pack. There's a big separate opening below the grill area that , as designed would just send air under the MH. I put a sheet of aluminum made from a "Road Construction" sign , angled to force all that air straight in to the cool pack. Even the mechanics that changed the engine said that was a good idea and they liked my blower ducting on the Port side of the engine. However, it was not enough to save the old engine, but they even said, 'it can't hurt'.
-- Previously Posted by Max

If you're moving this seems like a good idea. Seems like alot of people have found this to be a solution to stop the loss of air downward and under the frame.

But, what about when the unit is at a stand still or in slow go traffic situations? Isn't this a restrictor of air flow in no or slow go situations?

UPS man just delivered my two Attwood 4" In-Line Bilge Blowers (230 CFM each). Plan to put two air scoops under the pannel that Max describes above for passive air / bilge blowers that will empty at the front of the air dam and hope side dam pannels will help direct fresh cool air flow over enitre engine. If at the very least I should be able to cool the doghouse down faster with the blowers postioned in front of the doghouse.

I now have 2- 4" blowers, one for each side, I try to always remember to turn them on when in stop & go traffic and when the engine is working hard , climbing mtns or any time the engine goes over 200* + or - a degree or 3. I decided to have the outlet ducting from the blowers coming out pointing at # 5 and 6 SPs since they have been the problems. I hope it has a venturi effect to keep air moving across the entire banks.

quote " bilge blowers that will empty at the front of the air dam and hope side dam pannels will help direct fresh cool air flow over enitre engine. "

I did'nt understand " empty at front of air dam" , I would say mine empties behind the air dam.