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Old 05-24-2007, 06:54 AM   #1
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1990 33' Land Yacht
Jacksonville , Florida
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Bypass TBI water jacket????

What effect will bypassing the heated water jacket under the TBI have on my 1989 454?

Intuitively, a colder intake charge should result in better performance. HST, there is a danger of poor atomization and "puddling" beneath the TBI. Is that why the water jacket is there to aid atomization and prevent puddling under all driving conditions?

Is the heated water jacket a cold weather requirement? Or is the heat required for normal driving?

I have installed a Banks PowerPac, Gear Vendors, 180 degree thermostat and a MSD 6 ignition (10 degrees advanced). No chip as yet. Engine generally cruises with water temperature at 190 to 210 degrees, depending on outside air temperature and load (hills).

Im always looking for improved mpg and power.

I took the hoses off because they need replacing due to old age and decrepitude, and after I got them off, the thought occurred to me that I might get a smidgeon better performance with the cooler intake air charge.

The possible downside is the aforementioned poor atomization and/or "puddling." IAE, it will be easy to replace the hoses, if I have to, if the experiment doesn't work.

I was hoping that someone on the forum had experimented with taking the heat out and could get back to me with their results.
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Frank and Susan Davis
Jacksonville, Florida

33' 1990 Airstream Land Yacht: Edelbrock, Banks, Gear Vendors, MSD, Taylor wires, Super Steer bell cranks, Bilsteins, Roadmaster sway bar, Safe Steer, Pressure Pro, Crossfire, Bigfoot levelers, Rickson 7.5" rims & 245/70 R19.5 Bridgestones on steer axle.
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Old 05-28-2007, 06:55 AM   #2
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Frank, great question. The thought that comes to mind is about circulation after the TBI. Where does the exit flow go? What is your air intake situation? See my air intake box mod.

I'm back to thinking about switching to electric fans and getting rid of the clutch fan.

The new alternator is putting out so much that I figure I can afford the little draw from the fan (s) and reduce the engine load.
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Old 06-14-2007, 10:58 PM   #3
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1990 33' Land Yacht
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Glen,

The flow is FRom a fitting on the center FRont of the intake manifold through a hose to the base of the TBI water manifold, out the rear of the TBI water manifold and through another hose back to an array of hoses which I presume are part of the hot water heater "pre-heat feature" and then to the radiator.

Assuming there is room, I will probably run a hose directly FRom the intake manifold fitting to the return line, bypassing the TBI water manifold.

OTOH, I may incorporate a shut off valve so I can have it both ways. Haven't decided on final course of action, just yet.

I've also considered replacing my engine driven fan with an electric fan. That will be an '08 mod, I expect.

Susan and I are preparing to leave August 1 on a three month road trip FRom Florida to Maine to Kali-Fornia & back to Florida, via, among other interesting places, Yellowstone, Reno (National Air Races), An Francisco (son and wife), Coronado (daughter and family) Albuquerque (International hot air balloon festival) and Texas (Susan's FRiends and her sister).

Yee! Haw!

Don't have time to replace the engine driven fan before we leave.

FReegards,

FRank
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Frank and Susan Davis
Jacksonville, Florida

33' 1990 Airstream Land Yacht: Edelbrock, Banks, Gear Vendors, MSD, Taylor wires, Super Steer bell cranks, Bilsteins, Roadmaster sway bar, Safe Steer, Pressure Pro, Crossfire, Bigfoot levelers, Rickson 7.5" rims & 245/70 R19.5 Bridgestones on steer axle.
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Old 06-15-2007, 05:46 AM   #4
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Frank, all I can say is, "do you need a pilot?" Baggage handler?? Hope you'll be taking your camera and laptop so that we can see what you see along the way.
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Old 06-15-2007, 06:42 AM   #5
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The hot water is to limit icing in the throat of the throttle body, and it is important to have it in place when the temps are anywhere near freezing. Normally a motor home is not used when it is that cold, but first thing in the morning in the mountains in the spring or fall, the temps will be hovering around 40 or less.
The fans are a good idea, but they can draw 10 amps each, if you can hook up a temp sensor to activate a relay to turn on the fan when needed, it will draw about 12 amps, but only intermittently. You could locate the sensor in the neck of the water outlet (thermostat housing), or in the upper radiator hose. I have seen kits for this, you can probably still find them from JC whitney.
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Old 06-15-2007, 07:43 AM   #6
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Glen,

LOL!

Yup -- we'll have both, and hope to document the trip well. This being our "Rookie pass," howsomever, we just may have to do it again next year!
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Frank and Susan Davis
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33' 1990 Airstream Land Yacht: Edelbrock, Banks, Gear Vendors, MSD, Taylor wires, Super Steer bell cranks, Bilsteins, Roadmaster sway bar, Safe Steer, Pressure Pro, Crossfire, Bigfoot levelers, Rickson 7.5" rims & 245/70 R19.5 Bridgestones on steer axle.
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Old 06-15-2007, 07:47 AM   #7
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If I am hearing you right, I may have done this same thing to my throttle body on my 1996 LT1. I did this because even in cold climate around here I had no real issues. In severe cold however, it could have an impact, but I've been in -20 and no issues other than when really cold out and the engine is first started, the engine had only slightly higher RPMs until the engine warmed up a bit. What I did was take the feed and the outlets and connected them, in essence bypassing the throttle body totally. I think may be what you are trying to do and yes, cooler air is more dense and can provide a slight HP/torque gain. It made no sense to me to heat the air before it entered the engine and several folks on another forum agreed and did the same thing. It's not much of an improvment, if at all, but it made me feel better.

Because I have reverse cooling on the LT1 where the heads get cooled first rather than second, I put a 160 degree thermostat in mine. In winter I do have to place some cardboard over the radiator fins to restrict airflow and some times I've even taken off the fan belt that drives the fan only. Small price to pay for an engine to run 20 degrees cooler. It does however pay off when the car was used to tow or placed in a severe duty situation. The engine and trans did benefit as the both temps were about 15-20 degrees lower than that were when I had the stock 195 degree thermostat. When not in severe use, the engine would park around 165-170 depending on how liberal my right foot was and the outdoor amb temp.
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Old 06-15-2007, 07:48 AM   #8
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1990 33' Land Yacht
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Overlander,

Thanks. I understand that TBI icing might be a problem in cold weather. Most of my driving is in warmer climates.

The thing is, the engine quickly heats up to its operating temperature and I feel that not heating the intake air any more than it is already heated by the engine itself will allow the engine to develop slightly more power and get slightly better fuel economy.

Of course, I could be wrong, and if I am, I'll change it back to stock.

As for electric fans, thanks for the numbers. I was not aware that they drew that much amperage.
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Frank and Susan Davis
Jacksonville, Florida

33' 1990 Airstream Land Yacht: Edelbrock, Banks, Gear Vendors, MSD, Taylor wires, Super Steer bell cranks, Bilsteins, Roadmaster sway bar, Safe Steer, Pressure Pro, Crossfire, Bigfoot levelers, Rickson 7.5" rims & 245/70 R19.5 Bridgestones on steer axle.
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Old 06-15-2007, 04:20 PM   #9
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1990 33' Land Yacht
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Silvertwinkie,

You did exactly what I am going to do.

Glad to hear that you are happy with the arrangement. Since I live in Jacksonville, FL, and do not travel in (or near!) extremely cold climates, I do not see the absence of hot water under my TBI as a problem.

I have a 180 degree thermostat -- engine runs at 190 - 200 degrees on 90 degree days, and somewhat cooler on cooler days, which is fine with me. As long as it stays under 210 in the hills and mountains, I'll be OK.

I do think I'll wire the AC condensor fans (dash AC is not working) to their own switch so I can turn them on if/when the temp gets to 210 in the mountains.

I also installed a Banks PowerPack kit, which includes a CAI intake. I believe that disconnecting the TBI water heater can only help the engine perform better, albeit only a little bit.

But, hey! I'll take all I can get!

FReegards,

FRank
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Frank and Susan Davis
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33' 1990 Airstream Land Yacht: Edelbrock, Banks, Gear Vendors, MSD, Taylor wires, Super Steer bell cranks, Bilsteins, Roadmaster sway bar, Safe Steer, Pressure Pro, Crossfire, Bigfoot levelers, Rickson 7.5" rims & 245/70 R19.5 Bridgestones on steer axle.
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