blower on a JK-pros/cons

[Hilldweller]

I don'rt really know and I won't be getting one anywho !

:costumed-smiley-007:wings: JIMBO

Don't drive one then.
Or you'll be buying one. It's worlds better. Completely different vehicle.

 

[Scott Brady]

I drove a 3.8 with the Vortec blower. It was a nice improvement, nearly putting it on par with the 3.6- sounds cool too.

 

[Hilldweller]

I drove a 3.8 with the Vortec blower. It was a nice improvement, nearly putting it on par with the 3.6- sounds cool too.

I do love the sound of a blower.

But it's a no-no on the official Scott Brady Top Ten List of things not to do on an ExPo rig... :ylsmoke:

 

[JPK]

I have 2010 JKU with a Hemi, the 545rfe five speed auto, 4.88's and 37's. I average about 13mpg around town in mixed heavy traffic driving, 15 to 16 on the highway, even better if I limit spped to 65mph, which I don't often do.

My wife has a 2008 Rubicon 42rfe auto with the 3.8, with the oem 4.10's and the oem 32's. There is no fixing the 42rfe four speed transmission. The gap between the 1:1 third gear and the .67:1 O/D fourth gear is just too much. Driving her Jeep is what lead me to a Hemi.

Her milage around town is better than mine by ~4mpg, but there isn't that much difference on the highway (if I stick to the speed limit like she does.) Moreover, my highway mileage is better than a lot of similarly set up JKU's with the 3.8. (Bumpers, winch, skids, other stuff adding weight.)

The 2012 autos are an incredible improvement, and we will head that direction for my wife soon, though she has only 18k miles on her 2008 Rubicon Unlimited.

If you're stuck with a 3.8 and 42rfe the best option imo is to put a Hemi in it. On road performance improvement is a given, but the improvement off road from the abundant torque is hard to fathom if you haven't driven both a 3.8 and a Hemi JKU similarly set up. The Hemi gives fantastic control and does everything effortlessly compared to a 3.8.

If you're "stuck" with a 3.8 and the 42rfe then the best you can do is re-gear, which helps a lot, but it is no fix because of the unfixable gap between third and fourth.

As already mentioned, if you own any 3.8 and 42rfe combo, don't go drive a 2012 unless you're ready to switch, because either you will or it will be killing you until you can.

BTW, even the 3.8 has more torque at all rpm's than the venerable 4.0, the JK's are just bigger with more wind resistance. The 3.8, 42rfe, 4.10 and 32" tire combo is quick enough to be fun around town, its the gap between third and fourth that makes it suck on the highway.

On both JeepForum.com and JKOwners.com there are lots of reports on RIPP MODS centrifigul SC's. Many reports of pleased owners, a few bad reports and some seem suspect to me. Some guys have accumulated lots of miles and report no trouble. But Alpars also reports that Chrysler dropped plans for a turbo minivan when the bottom end of the 3.8 proved incapable of handling the stress at even "low to moderate" boost. Even with a SC, there is no fixing the 42rfe's gap...

JPK

 

[Hilldweller]

The 2012 autos are an incredible improvement,...

If you're "stuck" with a 3.8 and the 42rfe then the best you can do is re-gear, which helps a lot, but it is no fix because of the unfixable gap between third and fourth.

As already mentioned, if you own any 3.8 and 42rfe combo, don't go drive a 2012 unless you're ready to switch, because either you will or it will be killing you until you can.

JPK

Quoted the parts that should be in bold...

 

[JIMBO]

:sombrero: Evidentally you didn't read a word of my posts-

I have 2010 JKU with a Hemi, the 545rfe five speed auto, 4.88's and 37's. I average about 13mpg around town in mixed heavy traffic driving, 15 to 16 on the highway, even better if I limit spped to 65mph, which I don't often do.

My wife has a 2008 Rubicon 42rfe auto with the 3.8, with the oem 4.10's and the oem 32's. There is no fixing the 42rfe four speed transmission. The gap between the 1:1 third gear and the .67:1 O/D fourth gear is just too much. Driving her Jeep is what lead me to a Hemi.

Her milage around town is better than mine by ~4mpg, but there isn't that much difference on the highway (if I stick to the speed limit like she does.) Moreover, my highway mileage is better than a lot of similarly set up JKU's with the 3.8. (Bumpers, winch, skids, other stuff adding weight.)

The 2012 autos are an incredible improvement, and we will head that direction for my wife soon, though she has only 18k miles on her 2008 Rubicon Unlimited.

If you're stuck with a 3.8 and 42rfe the best option imo is to put a Hemi in it. On road performance improvement is a given, but the improvement off road from the abundant torque is hard to fathom if you haven't driven both a 3.8 and a Hemi JKU similarly set up. The Hemi gives fantastic control and does everything effortlessly compared to a 3.8.

If you're "stuck" with a 3.8 and the 42rfe then the best you can do is re-gear, which helps a lot, but it is no fix because of the unfixable gap between third and fourth.

As already mentioned, if you own any 3.8 and 42rfe combo, don't go drive a 2012 unless you're ready to switch, because either you will or it will be killing you until you can.

BTW, even the 3.8 has more torque at all rpm's than the venerable 4.0, the JK's are just bigger with more wind resistance. The 3.8, 42rfe, 4.10 and 32" tire combo is quick enough to be fun around town, its the gap between third and fourth that makes it suck on the highway.

On both JeepForum.com and JKOwners.com there are lots of reports on RIPP MODS centrifigul SC's. Many reports of pleased owners, a few bad reports and some seem suspect to me. Some guys have accumulated lots of miles and report no trouble. But Alpars also reports that Chrysler dropped plans for a turbo minivan when the bottom end of the 3.8 proved incapable of handling the stress at even "low to moderate" boost. Even with a SC, there is no fixing the 42rfe's gap...

JPK

I have no need for a "HEMI", or the 3.6L, course my Rubi is a little different than most and it's notta DD-99% off-road, but

Getting to and from the off-road, towing trailer--the 42 RLE and 3.8L is very satisfactory--I don't drink or do drugs !

Whats so hard to understand about my mods and improvements ??

:ylsmoke: JIMBO

 

[Hilldweller]

Jimbo, you're not average...

 

[Rovertrader]

Well, here is the deal for me. I went with '11 nonrubi w/3.73s. Why? I elected to go with a Mojave that the dealer had for 3 months, and got it at cost minus all the holdback. And, he gave me decent $$ for my PW -back in near stock form. And, for the $$ saved I can regear, add Detroits F&R, an Atlas, and pay for half of a high pinion HD44 in front. I have been at this game for 40+ years, but do not claim to know it all. Point being, my PW, like Bill's, had 400hp and 4.56s and I went from stock 33s to 37s and had no issues- at all. I went to the PW from a '07 Rubi for all the reasons listed in post above. I now have a F250 w/ 400hp and 800# torque, so the PW was replication. Also, my '06 TJ on 40s w/ coilovers had 4.88s and did fine w/ the 4.0, and 4:1 Atlas. So, all that said, I am trying to decide- gears, etc to save a bit of $$ and not do a full bore build yet again- and possible blower if it makes sense. Or, do the Hemi/5-spd, and be done. I am a bit tired of doing the same trails and the kids are enjoying water sports and camping, so in all realities, I am trying to build a comfortable highway traveling truck that will see some trails, FS roads, etc and get decent fuel mileage as fuel will eventually take another hike. I would seriously consider- and prefer- a decent diesel, but the electrical interface is a pain. Funny part is, driving it around town is a blast in stock form- doesn't need 4th, no trailer, 32s, life is good. But not so much loaded doing 12 hr days cross country or up to New Foundland, etc. Bottom line, need decent power and better fuel economy. The 3.6 offered little gain in added fuel efficiency, hence the '11- after waiting a year for the 3.6. Most reports conclude minimal increase in usable power, so didn't want to be first year in new drivetrain vehicle(yes, I know it has been out in other applications). In all honesty, the 6 spd 3.8 would probably be the ticket, but not with an 8 year old total L knee...
Sorry to ramble, but anxious to get the truck done, and trying to be prudent before starting. Funny to me there are so many JKs and so many opinions. Seems there would be more of a mainstream answer. I guess we just have so few options on the Rovers.
Thanks for all the replies, please continue, Cheers all!!

 

[Hilldweller]

Are you going to pull a trailer with it, Dale?
How big on the tires?

If no trailer and 33s, install 4.56s and declare victory.
33s and a trailer, think of the 5.13s.

35s? Nothing less than 5.38s.

And a 2.5" Rock Krawler lift...

 

[Rovertrader]

JJ trailer, thinking the new 285/75-17 KM2s (33.9") or Toyo (34.0) and a 2" or leveling kit. I would think the 285s would help considerably on the fuel mileage(saves almost 1.5" width x4) and either 4.88s or 5.13s. The blower would make the 'sweet spot' much bigger to hit... In the end, just wanting to build a true Expedition truck, not another trail rig or rock crawler(see sold section of my website for a look/see at a high dollar TJ- the friggin axles cost almost as much as this JK).

 

[Hilldweller]

The blower would work until it doesn't... ...know what I mean?
You'd still want an aftermarket trans cooler ----- 4.88s with the blower or 5.13 (at least) without.
And I wouldn't do a "leveling kit". I'd put a real lift, real springs, real shocks, control arms, adjustable trackbar, and Antirocks instead of discos.
Rock Krawler & Bilsteins or OME for a short one; Nth Degree for a 3.5" if you want.

 

[njjeepthing]

Jimbo- what size tires are you running with 5:38's?

 

[tj cruiser]

"extreme 4x4" did a side by side comparison power to cost on a JK stock, with a Hemi and a turbo. the turbo won out over all. Google "extreme" for the results. the addition of the turbo and all need stuff was about $5000 in costs, the Hemi was around $18,000.

 

[JIMBO]

:sombrero: I'm running Hankook Dynapro MTs 33.6" /75x16s

Jimbo- what size tires are you running with 5:38's?

Thats what all my rpm/mileage figures are with-

If you run 35/37s you're right back to the NO O/D use and loss of power-

These tires are the "sweet serenity"--

:costumed-smiley-007:wings: JIMBO

 

[Rovertrader]

The blower would work until it doesn't... ...know what I mean?
You'd still want an aftermarket trans cooler ----- 4.88s with the blower or 5.13 (at least) without.
And I wouldn't do a "leveling kit". I'd put a real lift, real springs, real shocks, control arms, adjustable trackbar, and Antirocks instead of discos.
Rock Krawler & Bilsteins or OME for a short one; Nth Degree for a 3.5" if you want.

Agreed, leveling kit to me is new hardware, not spacers, etc. I had OME first time, and really like the AEV Nth Degree 3.5" but want to keep it lower- no rock crawling this time around. Even considered tube fenders and 2" for the 34/35s. Sadly, I have a fresh set of 37s and trying NOT to be tempted...
Bottom line, the blower is a concern, and will most likely opt for 5.13s, 2/1" lift, and 34s, but still debating.