Engine power issues with 37's?

[Rumbloki]

I went from 32s to 35s on a Rubicon with 4:10 gears and never felt the need to regear.
A 2.7 Bronco with 4.46 or 4.7 will handle 37s just fine.

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[EOSeabee]

I went from 32s to 35s on a Rubicon with 4:10 gears and never felt the need to regear.
A 2.7 Bronco with 4.46 or 4.7 will handle 37s just fine.

Excellent! Thank you!

 

[BlueBronco]

Yeah, with the 2.7 EB and 4.7 gearing you have a near perfect set-up for 37's

Engine power issues, lol.

 

[HeliPilot]

I have the Proclal tune as well as well. I'll definitely calibrate the speedo when I get the tires. What tires did you go with?

37” KM3’s

 

[Bradley Thornton]

I have the 2.7 with 4.7 gears with 38s. I've let a few friends drive it and they are always impressed by the power it still has great seat of the pants feel.

 

[Fordified1]

The only thing that will really change is the amount of time it spends in 10th gear. I wouldn’t let that bother me. Shift it manually if it constantly hunts gears on the interstate. You’ll still smoke 99.9% of the Jeeps in a drag race.

 

[Mdsuits]

You will notice the difference….but it still has plenty of power….

 

[FreddieLee]

Depends on the weight of the 37's....

 

[userdude]

You can't just throw 37's on any truck or Jeep and think things will be kosher, since the gearing and the comparative weight/size upgrade can make a big difference. Plus the older Jeep engines weren't great. However, with the 2.7 and the ProCal, you might feel a little lag, but I doubt you'll even notice after a few weeks.

As somebody mentioned, try to get lighter rims (Method bead grips 25-30lbs) and go for a mid-range weighted tire (+=65lbs) like a Baja Boss or Kenda Klevers. You'll add some weight but not as much, at least. Be wary of tires that weigh perhaps above 75lbs.

 

[Bentpushrod]

Most definitely can feel the loss of power going to 37’s. Also a big loss in MPG. Is it worth it? Depends, I have no plans to go back to 35’s, and am perfectly happy with the loss in power and MPG’s.

 

[CarbonSteel]

Both! Lol. But his is a pavement princess. He has a friend who has a 2-door Jeep. He put 37's on it and the engine power went to crap. He ended up changing out his rear end. My friend also put 37's on his F-150 Raptor and had a similar result.

A Jeep (particularly the 3.6L) cannot handle 37's without re-gearing and even then it is a struggle if at altitude. I had 4.88 gears at sea level and 5.13 at 7K feet.

You have 4.7 gears and an engine that produces plenty of torque. I think you will be fine.

 

[Krimzun]

37 KM3's lift, exhaust, rock rails, bumpers, cai, ford performance tune on the 2.7L and its very fast on 93 octane. I used to own a Challenger with the 5.7L hemi and a 392 getrag rear end. I could hit 0-60 in 4.5 all day. The Bronco with all the extra crap is in the low 7's could easily get it into the 6's with down pipes and a better tune maybe even upper 5's.

 

[Felix808]

You'll be fine with 37's, 4.7's & the 2.7.
If you want great, add Whipple Stage 1.
I can still spark the tires with all the extra weight I've added & it will get up and go from 70-85+ with little effort when called upon

 

[HighVelocity]

Fill the tires with helium.

 

[GRIFFINCONWAY]

I have heavy 37’s (Mickey Thompson Baja boss AT’s and kmc grenade headlock) with the 2.7L engine and 4.7 factory gears. I saw a hit in my mpg going to that heavy of a wheel and tire setup but it looks great and still has plenty of power in my opinion. FWIW the Bronco Raptor has the same 4.7 gear ratio.

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