Bolt on Power and MPG

[wADVr]

I had my 1990 XJ pretty dialed.

renix 4.0 w/auto
ford MS 5.0 injectors (best mod)
Airflow snorkle (also a good mod)
Borla header
Rustys 2.5 flowmaster eshaust w/ hi flow cat
4.56 gears and 33s

Had plenty of power and was capable of 20mpg even loaded down and up and down passes.

best mods were the injectors and the snorkle. both mods were noticable. the header and exhaust-not so much.

The renix 4.0 has a lower rpm tq peak and produced the best usable power of any XJ I have owned. (89,90,94,96 and now a 99)

 

[Root Moose]

When I asked them about data they asked if I could feel it. I said I could feel that the shift points changed but I can't tell if there is more power. They said "well if you can feel it it must be working."

LOL

Butt dyno never lies. Hell of a foundation for a company... that pretty much says it all right there.

 

[willyswagon]

Keeping with the original thread question. I removed the K&N air filter that was in the Jeep when I bought it.
Returned to the OE filter, and found it seems to be better at low and mid range. So I guess that would be unbolting for power!:Wow1:

The other unbolting will happen in a couple of weeks when I take off the RTT and Congo Cage.

The rack caused the fuel consumption to go from 13.5l/100km(20mpg) to 17l/100km(16mpg), followed by the tent causing consumption of 18.5l/100km(15mpg)


So it appears to me that removing bad air flow is the best way to "Unbolt for Power".

 

[The Adam Blaster]

I had my 1990 XJ pretty dialed.


ford MS 5.0 injectors (best mod)
Airflow snorkle (also a good mod)

I've got the ARB snorkle on right now, and I have seen pics of the Airflow, and I like some of the design and fitment a lot better than the ARB. Most notably the complete lack of a 4-foot long corrugated tube that over time gets brittle and ends up cracking and tearing. <-- Not that I'd know anything about that...
And the kicker is that no one stocks just the tube, it's a special order item and can take months to come in and costs around 200 bucks. No thanks...

Anyways, with the airflow, do you happen to know if it uses the same hole placement in the fender as the ARB?
I'm thinking about combining the 2 kits and getting the best of both worlds, and never having to replace that stupid tube with a foil dryer vent hose. <-- Again, not that I'd know anything about that... lol

Regarding the injectors, how much are they, where do you buy them, and how long does it take to install them?

 

[K2ZJ]

I have a 95 ZJ with a 4.7 stroker. I did have a 4.0L in it for almost 10 years. I did most of these mods to it before the stroker swap this spring. Air intake and full exhaust header to tip (the best) had the most seat of the pants power, and an mpg improvement Ignition was a not much of an improvement. Poweraid tb spacer made more noise, tiny seat of the pants power. Same for the bored tb, 60mm. But truley the best is to regear. Over the years I went from stock 225-70-15s, 30s, 31s and to now 32s, with 33s in the garage. Stock I had 3.55s and bumped up to 4.10s afters having 31s for a while. I live in Colorado and the altitude combined with the long hills, I was CONSTANTLY down shifting and flooring it. The regear put me below stock for a bit with the 31s and real close to a little over with the 32s. Now that I have the stroker I am going to 33s. I am actually getting better milage with the stroker than stock I think because I dont feel the need to floor it to get moving, same as a regear. It is not running the best but I am working on it.

As for the 99+ intake here an article from another board with dyno runs beofre and after.

http://www.mallcrawlin.com/forum//showthread.php?t=6355

I also agree with the roof rack removal. I have a cargo top carrier, I boxy one, and it sucks down my gas. It really is a huge sail up there.

 

[wADVr]

I bought the injectors from a local shop but pretty sure Summitracing would have them. IIRC it was less that $100 for 6 of them and the install was only an hour or so. The Airflow snorkel uses different mounting and I dont think it would cover the holes left from the ARB. I have seen an ARB snorkel that the outlet was modified and simplified similar to the Airflow but dont have any pictures or link.

 

[MOAK]

Rockit

" Rockit" air intake, with K&N, bolted unto the stock six gasser, gets me 1 more mpg than stock box, and makes the throttle feel lighter.

 

[RunninRubicon]

Here's two, TJ and a JK

03' Rubicon
36,104miles with 33'x12.50x15 BFG MT
4" Pro-Comp w/johnny-joints
Rugged Ridge 60" front bumper w/Champion 8K lb wench (cable)
4wd specialists rear bumper w/tire carrier, rock rails
6-point roll-cage, w/48" high lift jack, 2 fire-exting. CB Radio
4680lbs, K&N "cool-air" tube, 5-speed stick 4.10 gears (stock)
0-60 mph=10.8sec averaged 15mpg @ 65mph, 80mph was about it.

Added a Kenne Bell 6psi supercharger w/Optimizor ECU
Magnaflow header to tail pipe exhaust (yes new cats)
Snorkel for high water but engine breaths via KB air box (under fender)
0-60mph-8.6 sec. 12.8mpg (best) @ 65mph. Easily topped out ECU in 4th or 5th 105mph. Approx 295hp/400ft/lbs of torgue. guzzled gas
$4K add on. Weighed 4865lbs afterwards. soft-top
Nearly invisable. Ran like a small block V-8.
Gas-mileage fell to 8-10mpg w/trailer.

 

[RunninRubicon]

second of two-JK

08' Rubi Unlimited 3.8L, 6-speed,full door, and hard-top, stock tires and gears
OME 2"+ lift, Skid-row evap and engine skid
Air-aid, Gibson exhaust

stock vs. bottom row above..
advertized to dyno 11hp & 13 ft/lb with air-aid and 10-20hp more for the Gibson. (these are what each manufacture advertise)
THE reality is at just off idle it's somewhat flatter in torgue then stock.
As the dial rises so does the performance. Remarkably over 4k to red-line, these mods say hello sincerely. Quicker then stock 0-60mph by 0.4 sec
The exhaust is noiser then I really care for but I like the performance.
The Air-aid howls so the Gibson covers this.
MPG (stock) 17mpg in town and 20mpg on the highway @ 65mpg
(mod) 18.5 in town and 22-24mpg over the same highway.
breaths easier and pulls my 2000lb off-road trailer easier, espeically up long hill climbs.
approx. $331. for Gibson (Summit Racing) and $287. for the Air-Aid
Someday it will pay for themselves in gas savings.

 

[Topgun514]

Sorry to bring this back from the dead, but I have to add my bolt on here.

Performance is a Cherry bomb glasspack (hated on but free-est flowing and does not sound bad at all, I promise)
Cut air box
Took out air intake silencer (look for go-jeeps) its about 1/4 mpg better

Those are pretty cheap and easy but barely any notice in power, but I did just order a 60mm bored TB from strokedjeep.com from Jeff.

The jeep feels like it did when I had 235s on it instead of this big heavy 31's. My power/butt dyno/ whatever you want to call it feels much better especially on hill climbing at speeds (highway, etc)

I would love to dyno test because this is the biggest increase in power I have felt.

 

[PMA4x4]

’96 XJ 4dr
145,000 miles
4.0L
AW4 tranny (rebuilt 23,000 with shift kit)
4.56 gears
33x10.50x15
4” lift

Bolt-ons are as follows
99+ intake upgrade
Edelbrock Shorty Titech header
2.5” exhaust
Magna-Flow hi flow 2.5” cat
Flowmaster Series 40 2.5” muffler
Preceision Auto Injectors 4 hole Bosch FIs
Fastman Throttlebodies 62mm bored throttle body
Custom 1” 62mm smooth bore TB spacer
Gibson Airflow Snorkel with

This whole project netted the following
2mpg gain
Easier/quicker starts
smoother idle
Crisper throttle
Faster revs
More power across the board (even though I did this just for the top end on highways)

 

[MOAK]

cold air

Back in 2000, I did a lot of research, and plunked down the green for a cold air intake, with a K&N filter. It was for my 98' 2.5 litre, and I noticed quite a difference in throttle response, especially right off idle. Good deal, as fuel mileage increased by a whopping .5 mpg. In 2004 I bought my current 4.0 litre, and without hesitation swapped in the cold air intake. Didn't think much about it, until recently I stumbled across some very negative reviews about cold air intakes, fuel mileage and overall vehicle performance. After long hard working highway runs the Rubi would, on occasion, diesel a bit during shut down, and idle roughly upon start up when hot. Fuel mileage was poor, 15.5 MPGs average. soooo, I removed the CAI, put the stock air box back on, with K&N filter. There is No difference in "seat-of-the-pants" throttle response, and by golly after 3 fill ups, I'm averaging 17.8 MPGs.. It doesn't idle rough any more, and the dieseling has stopped. The fuel mileage difference is remarkable, the CAI went on ebay, and I am a very happy camper!! Lesson learned....

 

[PMA4x4]

Rubicondon53,

You say "cold air intake with a K&N air filter". I assume this was another brand tube with an open air filter at the end if you just swapped it from one to another jeep? I ask because I purchased the K&N FIPK system and never regretted it for my 93 ZJ 4.0 I never had any symptoms you had.

For a brief while i had considered doing the same to my current XJ but decided to go the Snorkel route with a Wix Filter. I used to run K&N filters all the time but have noticed in a dusty environment such as Arizona there is a bit of dusting on the inside of intake tube.

 

[MOAK]

Rubicondon53,

You say "cold air intake with a K&N air filter". I assume this was another brand tube with an open air filter at the end if you just swapped it from one to another jeep? I ask because I purchased the K&N FIPK system and never regretted it for my 93 ZJ 4.0 I never had any symptoms you had.

For a brief while i had considered doing the same to my current XJ but decided to go the Snorkel route with a Wix Filter. I used to run K&N filters all the time but have noticed in a dusty environment such as Arizona there is a bit of dusting on the inside of intake tube.

Yes, just a tube with K&N filter. maybe if I would have spent the big money on the FIPK system you have, the results might have been better. I will add a snorkel at some date, as they are the only way to receive air from outside the engine bay. I began using K&Ns on baja buggies back in the 70's, never had any problems with dust getting through. Maybe Mojave dust is not quite so fine as your dust.. I've read that the reason for my 4.0 acting up with the aftermarket intake installed, was because the Map sensors could not get accurate readings. A chip is now available from "rockit" to correct the problem, for an additional 2 or 3 hundred dollars. instead of falling for that scam, I sell the intake on e-bay, and get the snorkel for the same amount of money... as I said,,, live and learn. The bigger question though, is why did the intake work so well on the 2.5, and was horrible on the 4.0? hmmmm...

 

[PMA4x4]

That is a good question, When I read that thats the point where confusion kicked in.

As for my FIPK. Yes it did work and I did notice difference but I dont know If i would lay that kinda money down again for a setup like that.