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Old 06-17-2003, 07:38 PM   #1
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Headers install update

OK, here's the after-action report.

30' '92 454 TBI 61 k miles, w/ 4L80E was getting 7.5 - 7.7 mpg solo at 65. Thorley headers ($420), Flowmaster 70 series 3" in and out ($99) used original cat and pipes, new Bosch plugs ($15), K&N ($35), dryer hose from aircleaner snout out to grill. 8 hours of nasty work (4 broken studs.) Thorley kit is excellent...everything fits. And it's not chrome, it's nickel.

Runs smoother, noise not an issue, more torque at 1500 rpms and up, 5 degrees less water temp, and 10.1 MPG. I know, I didn't believe it either. We went racing this weekend and ran 100 gallons through it coming and going. 10.1 mpg. Why anybody puts up with those stupid iron manifolds and burned plug wires is beyond me.
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Old 06-17-2003, 10:01 PM   #2
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High temp wires

When I put the Banks system on, I got an impressive mileage increase. As the temperature got hotter, however, I started to get some roughness and a drop in mileage. I attributed this to the OEM plug wires getting cooked by the increased heat from the manifolds.

I put on a set of 9mm high-temp (700-degree) wires and it is back to smooth again. I haven't checked the mileage, but estimating from gage movement, it is back up again.
John W. Irwin
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Old 06-17-2003, 10:38 PM   #3
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How many gears does your tranny have? I'm thinking of adding a GearVendor to mine as well as headers.
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Old 06-17-2003, 11:14 PM   #4
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Mine's a 4 speed. I think they went to 4 speeds in 90 or 91. I know my '88 454 Suburban is still 3. Check this out:
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Old 06-17-2003, 11:32 PM   #5
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I have to say that their music was quite catchy...I was able to read the whole page!
That 4 speed would be great except it seems that it's made specifically for higher horsepower monsters as in race cars et cetera. The gear vendor would give me 6 gears, but i worry (the bible says not to worry) I wonder if the constant shifting would bother me. I read a post who said that he missed his old 3 speed. But the gears are way too low for me...i need OVERDRIVE!

Thanks for that cool site. BTW, their music is still playing as I am typing this. Now it's getting to me. Ahhhhrrrgggg. must... hit... reply... key...
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Old 06-17-2003, 11:54 PM   #6
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I think we're looking at the top of their pile at 900 HP. We don't need all those super duty parts. Call 'em and see what a non-computer 4 speed for towing would cost. I'll bet they've made a bunch of them. Then you have to figure out how to blow your gearbox so you can justify the whole thing. I have a HD '88 454 Suburban that has your gearbox and I have a HD '01 Suburban that has the 4 speed, just like the Airstream. I got so mad at the 3 speed, I put huge tires on it to lower the revs at 65 mph. The 4 speed is a good piece. Get one used from from a Chevy 1 ton? The thing is to not need all the electronics.
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Old 06-18-2003, 07:04 AM   #7
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I found that site a few months ago. Looks like the 4L80E is a bit under rated. Who needs an Allison, when you have one of these.

What do you guys think of that "Pressureriser" control box???
I have no issues at all with my 4L80E and 454 in my 1 ton. It is a great combination. Thinking of doing a fluid change, not sure whether to go with a flush, or just change whats in the pan and filter. I am a few hundred miles short of 30,000.
2003 GMC 2500HD 4X4 D/A Ext. Cab
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Old 06-18-2003, 09:54 AM   #8
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Tranny 'flush' or Filter change


I just took in my LeSabre for transmission filter change and the reputable shop recommended a tranny flush vs the filter change.

He said that the flush changes ALL the fluid and is better than just the filter and add fluid method which is what I grew up with.

I went ahead with the flush. But for my towing vehicle I was wondering what the current BEST method is to do. Maybe doing both? Also thinking that I may want to do both on the first service at about 30,000 and go with a synthetic and douse the dino!

Since the tranny gets the most abuse, I think it needs the most attention. Mine is a 1/2 ton now with a 'underweight' transmission. I'd like to have what you have: the 454 and the 4L80E in a 3/4 Burb.

From some of the experts or those who have consulted from the specialists, what is the best route?

Steve in Savannah
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Old 06-18-2003, 12:45 PM   #9
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Full change is not that big a deal. Drop pan, change filter, fill pan-maybe 30-40 minutes. Pull IN hose - usually the bottom one - off the radiator, run the motor a little, pump old fluid into a bucket, replace hose, refill trans, clean up driveway - maybe 30 mins. Cost $35 for filter and fluid. Look for fine junk in the pan.
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