lngrn36

I'm wanting a little more performance out of my 2008 4.6L. I cannot find anyone that has a supercharger ot turbo kit for this engine. I've looked at the STS but I live in Houston where we have high water alot. At least the rear axle fluid is always new, lol. Anyway, I've come full circle to thinking of changing to CAI, tune and changing the gear ratio. Will I feel any change removing the 3.55 and going to 4.10?

ak_cowboy

Yes, there will be a big difference. Especially if you keep the stock size tires. Acceleration will be quicker, but top end and fuel economy will be lower.
Search around, gear swaps have been talked about quite a bit.

VanoFord

If you got the money for a Turbo system, I can show you everything you need to put one into your truck and not have it remote under the cab like the STS system. W/ turbo, tuner, fuel injectors, and misc piping, I ballparked a build for my 4.6L @ 3500. The turbo is half your cost, injectors are a good chunk as well. I plan on putting the turbo where the current air filter is located. Its just a matter of getting the piping in and out, which isnt a hard issue really.

As for your original post, AK_Cowboy is exactly right. You'll have great acceleration, jumpin off the line power, but your top end will be deminished along w/ mpg.

lngrn36

VanoFord
Yes, I have money for the turbo. But you and I work too much! My project just bumped me from 50 to 55. That should tell you that I have the money. If you were my next door neighbor we would be butchering it now! That top end fuel mileage concerns me a little because I drive back and forth to Bama some, but other than that it is just manuevering around slowpokes here in Houston! I drive it alot with the overdrive off. That helps, I would like a little quicker response off the line and in traffic. I'm really trying to see if I could get that by changing to 3.73 from 3.55

Cold

Don't waste your money on 3.73 the 4.10 are good and I'm putting in my 4.56's in 2 weeks when my buddy gets back from a class for work

lngrn36

Thanks! This is some info that I need.

Cold

I was looking at a RPM Calculator and with my 3.55 at 70mph the rpm's are 1916, with 3.73 its 2013, 4.10 = 2213, 4.30 = 2321, 4.56 = 2461 and that in OD which is a .70 trans gear ratio, with my 245/70/17= 30.5 tall tire so i can live with a 545 rpm diffarence so the question is what are you ok with??

Cold

With the OD off your 3rd gear which is a 1.00 trans ratio based on my tire size you are running at 2737 rpm's with a the OD off and at 70mph so its like your diving 80 with 4.56's so you MPG will be the same and you truck will not down shift going up hills!! Just alittle info i have compiled to help me choose!! Good luck!!

Cold

i also see you have 20's so your RPM's will be about 200-250 lower than mine

lngrn36

Good catch. I should clear up that sentence. I leave the OD off while driving around town. When the traffic clears up a bit and I'm closer home I can drive faster. When I can drive over 50mph then I turn the OD on to lower the rpm's, conserve fuel, and extend engine life. However I have entered the freeway a couple of times with OD off, and I'm like wow WTH! Then I look down and realize that my r's are too high and turn the OD back on. So if that is like 4.56, then that is some excellent info. It pulls like an SOB!