more hp

**ajstoy** · 02-28-2008, 06:58 PM

have an 07 fj, 6" suspension, 35x12.5 ex at's from pro comp...gas milages not great, but now.....deff not great......aside from air intake, throttle body spacer, and exhaust, what can be done to get more out of it? the supercharger would be nice, but the price...not what im looking for....any suggestions would be much appreciated

billybongo63 · 02-28-2008, 07:03 PM

Horsepower cost $$$,
sounds like you got the basics, maybe spark plugs to iridium.
With 35's regearing to 4:56 would give you more "umph"
but figure to spend 2K.
Save for the supercharger, it's worth it!
Nice looking ride-Bill

Fjamming · 02-28-2008, 07:04 PM

Smaller tires will help you move around faster. Not sure if that conflics with your plans though...

Disruptor · 02-28-2008, 07:11 PM

Get a chip like a unichip or the one from Underdog (then get it custom tuned), get headers, get a y-pipe... this should give you 2 to 3 more miles per gallon at the least and get a scan gauge help you keep your foot off the pedal as much.

Just a tip.. don't pay attention to the scan gauge's gas mileage reading when 4 wheeling.. lol.

Supercharger if you can afford it.. won't help much with mileage tho.

Disruptor · 02-28-2008, 07:12 PM

Quote:

billybongo63 previously said:

Horsepower cost $$$,
sounds like you got the basics, maybe spark plugs to iridium.
With 35's regearing to 4:56 would give you more "umph"
but figure to spend 2K.
Save for the supercharger, it's worth it!
Nice looking ride-Bill

Would regearing it to that hurt or help your mileage?

Fjamming · 02-28-2008, 07:14 PM

Quote:

Disruptor previously said:

Would regearing it to that hurt or help your mileage?

Help in most cases. You're lugging the engine otherwise.

**ajstoy** · 02-28-2008, 07:26 PM

thanx to all responding..has anyone used the unichip

**Toledo FJ** · 02-29-2008, 06:54 AM

Yes I have the unichip custom tuned with the mods you see in my sig. I got my unichip from a forum member who got rid of his because he supercharged. I think this was a mistake on his part because the Unichip can be tuned for a forced induction system like a Supercharger, as well as any other mod you do to your rig. Custom tuning makes a really big diff. I think the tuner got like 18 more HP than the gains you'll see from a factory mapped Unichip (which isn't bad to begin with). I highly recommend the Unchip an even more highly recommend a custom tuning. It isn't cheap though... The unichip will cost about 6 or 7 hundred new and the custom tuning and install was about $700 more. But now I'm actually getting the power out of all my other mods that I wasn't getting before the chip. Here is a link to my Dynamometer charts:

Unichip Computer module

Keep in mind these numbers are for the HP and Torque at the wheels, not the engine. We need to find a stock, MT FJ to throw on the dyno for a baseline graph. Then he can calculate the power at the crank.

punch455 · 02-29-2008, 10:12 AM

Quote:

Disruptor previously said:

Would regearing it to that hurt or help your mileage?

It would hurt you mileage.. alot. Increasing the gear ratio to a 4.56:1, you're going to notice a considerable increase in engine RPM per MPH. In other words, let's say you're on the highway cruising at 60 MPH, and your engine RPMs are at 1800. If you increase the differential's gear ratio, you will notice that under the same driving circumstances, your new RPMs are at 3200. Your engine is working almost twice as hard to maintian the same vehicle speed. But you will DEFinitely notice an increase in acceleration too.

Also, if you're gonna swap your diff gears with new ratios, make sure to do the same to the front too if it's a 4WD.

Fjamming · 02-29-2008, 10:57 AM

Quote:

punch455 previously said:

It would hurt you mileage.. alot. Increasing the gear ratio to a 4.56:1, you're going to notice a considerable increase in engine RPM per MPH. In other words, let's say you're on the highway cruising at 60 MPH, and your engine RPMs are at 1800. If you increase the differential's gear ratio, you will notice that under the same driving circumstances, your new RPMs are at 3200. Your engine is working almost twice as hard to maintian the same vehicle speed. But you will DEFinitely notice an increase in acceleration too.

Also, if you're gonna swap your diff gears with new ratios, make sure to do the same to the front too if it's a 4WD.

A lower gear doesn't always hurt the gas mileage. Sometimes you're cruising at a speed that makes the engine work harder then it should so it either hunts or lowers a gear. If the gear is properly set, it'll stay at a more constant speed and maybe even lower rpm because it doesn't have to down shift. Imagine driving a manual with only 3rd and 5th gear, you'd like to be in 4, but you can't and have to either lug the engine in 5th or rev it in 3rd.