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-   2005+ Jeep Commander XK (http://www.jeepgarage.org/f188/)
-   -   Looking to put my XK into the 14's w/no power adders (http://www.jeepgarage.org/f188/looking-to-put-my-xk-into-the-14s-w-no-power-adders-28664.html)

08Commander 09-17-2011 07:20 PM

Looking to put my XK into the 14's w/no power adders
 
Getting very close to edging my XK into the 14 sec. 1/4 mi. club. My goal is to build the quickest XK around my area (which I've already done)...then see how it competes on a national level with other builds looking for street performance and quick times outta a 5K lb. + beast like mine. My most current 0-60 mph time (using my SC flashpaq timer) is: 6.82 sec. This equates to a low 15 sec. quarter mile. Currently I have done every performance mod. that is offered for my model, would love to figure out how to get her into the 14's without a power adder. It's a work in progress, and fun. This is my 2nd Jeep after a long string of very fast street cars. I'll post up pics as soon as I am approved as a member.

Chaoul1 09-17-2011 07:38 PM

Re: Looking to put my XK into the 14's w/no power adders
 
You ported your TB? You need some Headers/Cams and definitely a tune.

FlyinRyan 09-19-2011 03:02 PM

Re: Looking to put my XK into the 14's w/no power adders
 
I have not done a 08+ 4.7, but I can taper port those. They are very similiar to the 3.7 which Ive done several of, with good results. May help you get a little closer.

I dont know how the newer 4.7s are set up in terms of exhaust but ditching the awful unequal length Y pipe that these Jeeps have had for years, for a basic true dual setup (X pipe, H pipe if space is an issue) would probably net some gains over what you already have.

Scottina06 09-19-2011 03:22 PM

Re: Looking to put my XK into the 14's w/no power adders
 
I have built an 08 4.7, stroked, forged and all and a simple cams swap would get ya in the 14's easy. But I had tuning from SCT on my 2006. The 2008 tuning is whats gonna drive you mad. Ryans ported TB's are great...but if you go with more aggressive grind cams...you will need a 72 or 74 F&B and some ported heads. You can also look into adding an extention to that hot air intake you have...for race days only.
Have you also looked into suspension? Maybe some lowering springs? Any wk or srt jeep lowering spring will work on the xk. Our vendor stage 6 has some nice 18 wat adjustable rear shocks.

Look into losing some weight too....spare tire, rear compartment plastics or rear seats.

FlyinRyan 09-19-2011 03:31 PM

Re: Looking to put my XK into the 14's w/no power adders
 
Quote:

Originally Posted by Scottina06 (Post 487061)
I have built an 08 4.7, stroked, forged and all and a simple cams swap would get ya in the 14's easy. But I had tuning from SCT on my 2006. The 2008 tuning is whats gonna drive you mad. Ryans ported TB's are great...but if you go with more aggressive grind cams...you will need a 72 or 74 F&B and some ported heads. You can also look into adding an extention to that hot air intake you have...for race days only.
Have you also looked into suspension? Maybe some lowering springs? Any wk or srt jeep lowering spring will work on the xk. Our vendor stage 6 has some nice 18 wat adjustable rear shocks.

Look into losing some weight too....spare tire, rear compartment plastics or rear seats.

He has an 08 it seems, which should have the Gen 2 4.7. So it already has a 74mm TB from the factory, albeit drive by wire.

Awhile back I had read about the SC programming for the new 4.7s, and from what I had heard and seen at my home track is that the performance with the tuning is DRAMATICALLY different. An acquaintance with a 2wd 08 Ram went mid 14s with a track intake, SC tuning, a cutout, and either tires or gears. He was IIRC running mid 15s in stock form.

Lowering springs are the last thing he needs, the improved aero would be nice but the increased spring rate would not be good for weight transfer. The shocks would help, though.

Scottina06 09-19-2011 03:39 PM

Re: Looking to put my XK into the 14's w/no power adders
 
I bet it was the gear change that got him there. And I was told the 08 4.7 had a 70mm TB....thanks for the new info. my 08 4.7 didnt have a tb with it and then i used the airram plate to switch it over to throttle by cable anyway.

The SRT guys will argue with you on the springs.....

FlyinRyan 09-19-2011 04:00 PM

Re: Looking to put my XK into the 14's w/no power adders
 
Quote:

Originally Posted by Scottina06 (Post 487072)
I bet it was the gear change that got him there. And I was told the 08 4.7 had a 70mm TB....thanks for the new info. my 08 4.7 didnt have a tb with it and then i used the airram plate to switch it over to throttle by cable anyway.

The SRT guys will argue with you on the springs.....

IIRC he simply used smaller tires/wheels. Ill have to dig through some old threads. Anyhow he didnt do it all at the same time, he lost like half a second on tuning/cutout alone.

From everything I have heard (and I think I did measure it at one point), the 08 is in fact 74mm. The 3.7s use a 65mm IIRC.

They might...I admittedly dont pay too much attention to what they do.

If they are launching so hard that they are bottoming out in the back, then yes, I can see why they would go to a stiffer spring. That in combination with punching a smaller hole in the air as they are going 100 mph down the track would show a potential gain. Same thing goes for if the rear end has alot of squat on the pass side, because of lost energy spent on twisting, again a stiffer spring would help (although itd be better just to have a helper bag on the pass side). Then you get into pinion angle and all that stuff...

Shocks from my experience play a bigger role in weight transfer, as long as the coils arent excessively soft/stiff/worn.

NHWK05 09-29-2011 01:47 PM

Re: Looking to put my XK into the 14's w/no power adders
 
2nd and 3rd row seats in the XK are about 250lbs total. Removal is a bioch but its alot of weight to loose. Spare is about 50lbs too. As far as springs go, putting a Commander to the track takes balls, its needs anything it can get to make it punch a smaller hole in the air in front of it.

08Commander 03-07-2013 05:49 AM

Re: Looking to put my XK into the 14's w/no power adders
 
Quote:

Originally Posted by Scottina06 (Post 487061)
I have built an 08 4.7, stroked, forged and all and a simple cams swap would get ya in the 14's easy. But I had tuning from SCT on my 2006. The 2008 tuning is whats gonna drive you mad. Ryans ported TB's are great...but if you go with more aggressive grind cams...you will need a 72 or 74 F&B and some ported heads. You can also look into adding an extention to that hot air intake you have...for race days only.
Have you also looked into suspension? Maybe some lowering springs? Any wk or srt jeep lowering spring will work on the xk. Our vendor stage 6 has some nice 18 wat adjustable rear shocks.

Look into losing some weight too....spare tire, rear compartment plastics or rear seats.

I've taken most of your suggestions and went with them. I removed and converted my 3rd row seating to the standard 2 row (and sold my equipment to an XK owner in Detroit who also gave me the pieces from his ride to complete and finish mine). I've removed the undercarriage spare tire, and now carry onboard 2 cans of Slime and a tire plug kit. I've also lowered my ride (overall it dropped 1 3/4" in back, 1 1/2" in front after settling). I've also removed the ski racks (never used actually) from the top. So I've shed approx. 180 lbs. And now I cut through the air a bit lower. Going to take her to the track this Spring when it opens and see where she is now. I know this still wasn't enough to dip her into the high 14's but I am for sure closer to my goal. I will keep everyone here informed of my progress. Thanks for the advice, and keep it coming!

hummer recovery team 03-07-2013 05:53 PM

Look forward to hearing more, I've modded mine extensively.


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