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Discussion Starter #1
first off you guys have been more than helpful with my previous posts about my stereo posts. but now i've got some questions about my performance. i've got a 94 bronco, 351w, flowmaster super 40 series with turndowns and running on bf goodrich 31x10's. that's it. my truck is a daily driver and i am not going to be lifting anytime in the next few years so i will be running the 31's. what i want to get out of my truck is better mileage and good power. currently i get 10.5 - 12 mpg. now, i plan on bolting on some longtube headers, k&n full intake system, air raid throttle body spacer, underdrive pulleys, an electric fan setup and a couple of those tornado fuel savers. but now it comes down to choosing to go with a new torque converter with a higher stall speed or upgrading the rear differential to 3.55 or 3.73 or 4.10. what should i do?:rockon
 

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first off you guys have been more than helpful with my previous posts about my stereo posts. but now i've got some questions about my performance. i've got a 94 bronco, 351w, flowmaster super 40 series with turndowns and running on bf goodrich 31x10's. that's it. my truck is a daily driver and i am not going to be lifting anytime in the next few years so i will be running the 31's. what i want to get out of my truck is better mileage and good power. currently i get 10.5 - 12 mpg. now, i plan on bolting on some longtube headers, k&n full intake system, air raid throttle body spacer, underdrive pulleys, an electric fan setup and a couple of those tornado fuel savers. but now it comes down to choosing to go with a new torque converter with a higher stall speed or upgrading the rear differential to 3.55 or 3.73 or 4.10. what should i do?:rockon

Are you serious? The K&N hot intake is worthless. The factory air intake has been proven to be very effective. Swapping in an air intake tube from a I6 or 460 F-series truck is about the only other option to consider. Throttle body spacers...what can I say. WASTE OF MONEY! Same for the tornado wallet biopsy devices. If you had did any research on this site you would find those devices are absolute crap.

The long tubes could get you some more power, but they require a custom exhaust to hook them up. Even then you could lose any gains by poorly routed pipes around the transfer case. Underdrive pulleys on a daily driver is not my first choice, other may disagree but I'll stick to factory.

The electric fan may net you a little MPGs, but there are other items to consider before going through the time and expense of installing only to find it did not help much.

Many here will tell you to start with the "Sixlitre" ignition upgrade. Next would be ditching the factory y-pipe and converters in favor of a y-pipe with a single high flow converter. Catco/Magnaflow/Bassani are some of the favorites. Don't even mention dual exhaust...another waste of money. Stick with a good 2.5-3" single exhaust with a muffler of your choice for the desired sound qualities you are looking for.

As for gears, what are you running now? Those 31" are sucking up some power and mostly likely MPGs. I would not consider a higher stall converter until you start making some serious HP with more bolt-ons such as intakes/heads/cam.

FWIW I am getting the same MPGs as you with my boat anchor F350 w/5.8L engine, E4OD, 3.55 gears, 31" tires. My pig is a lot heavier than yours as well as a little less aero. You should be much better mileage, but you also have to drive it like a truck and not a Mustang.
 

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I would also recommend a tune up to start with and see if that makes a difference. I drive mine everyday and it is totally stock except the 33's. I average around 14 mpg
 

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I agree with rla on some of it. dont waste your money on the throttlebody spacer and the tornado crap. If you are gonna redo the exhaust might as well go ahead and get the long tubes and build your exhaust for them. They arent that hard to install. Definitely do a good tune up on the bronco and look into getting a K&N air filter. Search around some lots of guys have made their own intakes that are pretty much the same as the k&n one for a lot less money. tons of threads about mpg around here
 

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first off you guys have been more than helpful with my previous posts about my stereo posts. but now i've got some questions about my performance. i've got a 94 bronco, 351w, flowmaster super 40 series with turndowns and running on bf goodrich 31x10's. that's it. my truck is a daily driver and i am not going to be lifting anytime in the next few years so i will be running the 31's. what i want to get out of my truck is better mileage and good power. currently i get 10.5 - 12 mpg. now, i plan on bolting on some longtube headers, k&n full intake system, air raid throttle body spacer, underdrive pulleys, an electric fan setup and a couple of those tornado fuel savers. but now it comes down to choosing to go with a new torque converter with a higher stall speed or upgrading the rear differential to 3.55 or 3.73 or 4.10. what should i do?:rockon

The tornado will just add turbulence to you're intake air, lowering horsepower, f-ing up mixture, making it run bad and generally just f'ing things up.

turndowns will = fumes in the cab. i recommend exhaust out the side behind the rear tires.

long tube headers will have clearance issues. and they won't gain you anything on a basically stock engine

the k&n hot air intake is garbage as stated so i wont get into that.

the throttle body spacer *might* move you're power band upwards very, very slightly if you're engine is cammed, headed and tuned properly. i'd skip it as it will also most likely just f things up at best.

underdrive pullys will just make you're water pump less effective, make steering not work as well at idle, make you're a/c less cold, make it harder to pass smog with the smog pump turning slower too. BTW it takes the same horsepower to crank out a given amperage (charge required) from an alternator regardless of the RPM the alternator is spun at (half the rpm will require double the torque, etc). you're a/c compressor will run a longer duty cycle as well.

the electric fan might save very slightly, if it's on a temp switch so it only comes on at radiator temp of (say) 160. if it's running constantly then it'll just increase electrical load, making the alternator work harder and ultimately robbing as much power as the stock mechanical fan. (while not cooling as well) personally i'd just make sure the stock fan has a good clutch and be satisfied.

a higher stall speed on the torque converter will LOWER gas mileage, create more heat in the trans (significantly more) and, unless you have a high RPM screamin' engine build (which you're stock engine is the opposite of) it will actually reduce performance, by not allowing the engine to run in it's torque band.


changing the differential gears (rear AND FRONT) will not raise you're gas mileage any. you're stock gears are probably 3.55 as these were most common.. which with 31's and an overdrive is the best you're gonna do for mileage. lowering gear ratio (high numerically, say 4.56) will make the truck get up n' go faster off the line, but again, at the expense of freeway mileage.

a free-er flowing muffler MIGHT increase you're mileage very, very slightly. (but never by enough to offset the cost of the new muffler install)

bottom line is, these are big heavy boxes and it takes a lot of fuel to move them. look up "sixlitre tune up" for a few tips though.. most of what's involved there is generally good advice
 

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I recommend an emmissions legal camshaft. Less that .5 inch lift and not to close a lobe separation. You will have to do your research but i think the best bang for your buck is going to be a mild Cam in the idle to 4.5-5k range. Give those big ass cylinders some better airflow and make the fuel you use work better for you. That and increasing your comp ratio is whats going to give you noticeable HP gains.
 

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I recommend an emmissions legal camshaft. Less that .5 inch lift and not to close a lobe separation. You will have to do your research but i think the best bang for your buck is going to be a mild Cam in the idle to 4.5-5k range. Give those big ass cylinders some better airflow and make the fuel you use work better for you. That and increasing your comp ratio is whats going to give you noticeable HP gains.
I agree that increasing the comp ratio may give some gain, but remember he has speed density injection which will need a reprogram for a non-stock cam, also remember that his stock e7 heads won't breathe at higher rpm (above 4k) even if the cam is bigger.. i still think the stock cam is the best option. and even with the relatively low (is it 9:1?) static compression he currently has, the stock cam closes the intake valve early enough that he's still got pretty good dynamic compression. this would be lost with a bigger cam and no compression change. also remember that increased compression also raises combustion temperatures which in turn increases NOX... which may prevent it from passing smog.

i dont mean to rain on anybodys parade, i'd just hate to see him do a ton of work and spend lots of money to just end up with a ****ed up truck that runs horrible and wont pass emissions.
 

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Discussion Starter #8
thanks a lot for the input. i guess then i'll start with a good tune up. yall said sixlitre? i'll research it and give it a try. so popular consensus is that everything i though i should do is not worth the trouble or money. thanks, that's what these forums are here for. shit i didnt know and yall did. again appreciate the input.
 

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thanks for the link. gonna upgrade to the sixlitre soon as i can. i actually slowed down my cruising speed from 75 to 65mph. gained about 1mpg. not great but still something, especially for a bronco. and i am gonna focus on my new stereo first. i was going to go with the alpine x305s, but recently changed my mind to the kenwood kiv-700. 22 rms x 4 and already set up for subs. but i'll still get another amp if i do get subs.
 

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but remember he has speed density injection which will need a reprogram for a non-stock cam,
Stop telling people this, it is wrong

Almost any cam can be used with SD as long as it has an LSA of 114* or better.


On a 351w, the best upgrade that can be maid is to ditch the factory intake manifold. After that, it's time for heads and exhaust.
 
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