Better MPG with crossover on dual exh?

[DSLPWRD]

My brother had dual exhaust, manifolds back, put on his 5.4l, and it seemed like the mpg has dropped like a rock. I thought i read something in 4-wheeler a while back, the the engine needs a crossover to stabilze one bank to the other? Am i all wet?

14-18 pre
11-13 after, even with the little lady driving

DSLPWRD

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01' F350, PSD, CC, LWB, Lariat, White w/gold, 3.73LS,6 disk cd
man 4X4, auto, 3x-A pillar mnt ,smells bad, hard to park, can't swing drive thru's!
I love this thing!?
Ordered 8-15
Built 9-18
My ars in it 10-4

[jimveta]

i have the same setup on my v10 as well (plus y-pipes).. and i think it has also dropped in mileage a little, though i haven't measured it. it's been a while and i've also gotten other mods since then so i can't really say what each one had on mpg but i'm pretty sure nothing helped it.

[Tim_wants_a_Silverado]

True duals on a new truck? With or without the cat?

A crossover pipe will most likely improve the mileage some, but if it made that much of a difference to put the exhaust on it, it probably won't bring it all the way back up.

I am putting duals on mine on Thursday, and I chose not to use a crossover because I don't like how it sounds with one on there. I figure I'll add one later if I want to.

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'84 Chevy K10 Scottsdale 4x4. 305 V8. 700R4. NP 208. 3.08 gears. 3" Suspension Lift. 35x12.50R15 BFG A/Ts
35x12.50 BFG M/Ts on their way

[NoMo]

Sounds like an awfully large MPG drop for just an exhaust. A crossover pipe just balances the exhaust pulses so that there is equal pressure on both manifolds. Doubtful it will help economy (maybe performance?).

Has anything else been changed? Did the drop occur all at once (immediately after the install) or, could this be a winter gas thing?

Have him "reset" the PCM by unplugging the battery for a few hours. I do this after any mod and sometimes just "because".

Finally, I don't know about his "little lady", but mine drives the dog-poo out of our vehicles. She thinks at least one of the pedals has to be on the floor at all times!


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2000 4x4 F250 XLT SuperCab SWB- V10, Automatic, 4.30LS, Offroad Pkg, Camper Pkg, OEM Hitch, Tape/CD Player, Remote Keyless Entry, Sliding Rear Window, Privacy Tint, Aluminum rims, 265/75R16 OWL tires, Line-X bedliner
NoMo's site

[Dr.Evil]

The balance tube will help on HP a little. I think it was worth may 5, not over 10 HP on the 5.0L HO. So it makes the engine a little more efficient, but as to making it more fuel efficient, it would be tough to measure in a laboratory, let alone the street. The drop in mpg from 14 to 18 to 11 to 13 must be mostly weather related. Oh, And Tim-wants-a-silverado, You going to put 35's on your new one too? What's your RPM at 65 mph in overdrive? about 950 rpm? And with a 305 no less....Most people would have a hard time deciding between 4.10's and 4.56's with 35's. I used to work with a guy who's son had a 2.3 L Ranger who went to 4.56's with 32's, Wished he'd gone 4.88's when he went with 35's. Bet they're 10-Bolt axles too aren't they.

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'96 F-250 4X4 5-sp POWERSTROKE
140,000 mile & NO Problems

[fwlaura]

I've got an '01 F-250 4x4 CC with the 5.4L & 3.73, I get 6 MPG, that's right 6 MPG. I'm hoping that it improves as I drive it (only has 250 miles on it). It's also cold here now 10-20 degrees for the high everyday.

Your brother should be happy :/

[wldwilliam]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by fwlaura:
I've got an '01 F-250 4x4 CC with the 5.4L & 3.73, I get 6 MPG, that's right 6 <HR></BLOCKQUOTE>

I can finally feel fortunate about my mileage

[Tim_wants_a_Silverado]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Dr.Evil:
Oh, And Tim-wants-a-silverado, You going to put 35's on your new one too? What's your RPM at 65 mph in overdrive? about 950 rpm? And with a 305 no less....Most people would have a hard time deciding between 4.10's and 4.56's with 35's. I used to work with a guy who's son had a 2.3 L Ranger who went to 4.56's with 32's, Wished he'd gone 4.88's when he went with 35's. Bet they're 10-Bolt axles too aren't they. <HR></BLOCKQUOTE>

I am swapping out my axles next month. Believe me, I would have never attempted to put big tires on this thing with these gears if I knew I'd have to live with it.

I'm getting a pair of 8 lug axles from an '82 Chevy K20. They have 4.10 gears, and consist of a 12 bolt semi-floater rear and a 10 bolt front.

One day I'm going to swap to 1 ton running gear (Dana 60/Full floating 14 bolt). But for now the 4.10 geared axles will do me just fine.

I can't pull the overdrive at 65 mph, or any speed for that matter. The RPM would be about 1400. I already know that it sucks! You don't have to tell me! But since I've already got the 4.10s coming, I don't mind suffering for a little while.

Cut me a little slack, I might drive a Chevy, but I'm not a total moron.

Added in Edit:
Right now my axles are 10 bolt front and 12 bolt rear.

Althogh I recognize the need for lower gears, especially with overdrive, a friend of mine with a TH-350 tranny has 3.08s and 38.5" tires. Think his lugs? He's got a 350 now, but there used to be a 305 in his. Future plans for mine include a 9:1 350, I just don't NEED that yet, and don't have that much money right now, I'm saving, and I'm only 17. This project truck is really hard for me at 5.65 an hour. But you have to admit, I'm doing very well for the money I make. But over the summer I make 10 bucks an hour, 40 hours a week. I just can't wait to go back to that job.

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'84 Chevy K10 Scottsdale 4x4. 305 V8. 700R4. NP 208. 3.08 gears. 3" Suspension Lift. 35x12.50R15 BFG A/Ts
35x12.50 BFG M/Ts on their way

[This message has been edited by Tim_wants_a_Silverado (edited 12-30-2000).]