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is the 4 cylinder platform worth the build?

28K views 53 replies 16 participants last post by  Ditchdoc 
#1 ·
My 98TJ just turned over 109,000 miles and is bone stock minus the 31"BFG's... I've been considering dumping some cash into it this summer, budget boost, 1" body lift etc... before I do so I wanted your opinions on if it's even worth it to start a build on a 4 cylinder jeep? I do not take it wheeling too hard (there's a few local class IV trails I frequent, but that's about it) but I have come across a few climbs that it just doesn't have the power/clearance to make... I wouldn't mind spending some money and lifting it and adding some cosmetic/functional offroad pieces, but at the same time I could probably sell it while it's still worth some money and upgrade to the I6.... thoughts?
 
#3 ·
id say depending on what you wanna do with it you want to make a serious rock crawler one day i have the 6 cyl and want a 4 cyl plus less gas. but for rock crawling iv heard that the weight differnce is almost 150 pds. and i know a few pro crawlers that want to put a 4 cyl in place and just put super low gears in it. but for trails and stuff it can really go either way. with 4 cyl your less likely of breaking an axle. just some stuff you can think about.
 
#5 ·
Here is my 4 cylinder with 4:88's and a Ford Explorer 8.8 rear end climbing through rocks and sand at EL Mirage a couple of weeks ago. It serves me well. Its locked front and rear. The only draw back to the 4 that I have noticed is it makes more noise on the freeway getting to the trail. It runs at 70 at 3000 rpm with 32" tires, and I am getting ready to lift it to 3.5 RE. and putting 35" tires on it. This should bring the RPM's on the freeway down. I really like my Jeep, but with that siad, I did just buy my wife a fully loaded 6cy with cruise. The only reason I went with the six was because of the comfort level on the freeway. Now I guess if you are into some serious rock crawling you might want a 6, but then again you may upgrade your 4 to an 8. So experiment with the 4. If you get the bug go with the 10K upgrade to an 8. Make sense? :wavey:



BTW the other Jeeps with me had 6" lifts, and 6 cylinders. :p
 
#30 ·
The only draw back to the 4 that I have noticed is it makes more noise on the freeway getting to the trail. It runs at 70 at 3000 rpm with 32" tires
Finally! i've been waiting for someone to give me an idea about what my rpm will be after gears. I'm guessing around 2875 with 33" tires for me then. Not bad considering I can only get to 3k rpm with the stock gears.
 
#6 ·
Don't underestimate the good ol' four cylinder. Hell the TJ's 4 banger has quite a bit more power than a lot of notable 4 cylinder off road vehicles in the past.

I hate to admit it, but I'm part of a Land Rover Club haha, only because of the lack of clubs in little Rhody, however I went trail riding with them a few weeks back, sadly I had just bought my TJ and hadn't looked it over for trail integrity, but we went with by buddy's 1978 Land Rover Series III with the following specs:

4 cylinder: 85 hp; 95 ft-lb of torque give or take
4 Speed Manual with manual overdrive
5.88:1 R/P Ratio
2 inch under axle parabolic spring lift
Procomp Shocks
32" Goodyear AT/S's
Aluminum Rock Sliders

Other trucks had bigger tires, "better" lifts, modern computer b/s, lockers, and V8s.

The series with it little 4 banger out climbed, and simply outwheeled every other truck, cause its light, simple, tough, and not powerful enough to break stuff, yet able to be a daily driver and the jeep wrangler is a similar platform, not by specs, but by characteristics certainly.

4 cylinders have been the heart of trucks that do important things for nearly a century, starting with Jeep.

Therefore, I say build it.:punk:
 
#9 ·
how big of tires do you want to end up with and how fast do you like to drive on the highway, the problem with the 4cyl is not on the trail, you can regear to get a really low gearing and go slow and use its torque, the problem is on the highway. My suggestion is to just not go as high, you can get a VERY capable rig with just 33's still
my suggestion is 3"susp. lift
1.25 in BL
33's
SYE/CV
tummy tuck
tube fenders
critical body armor (want to keep weight down though)
manual lockers front and rear
then touches like lights, bumpers, etc.
this will get you a good amount of ground clearance especially with the tummy tuck and a few skid plates so ur not as afraid of bottoming out, and still keep ur tire size small so you dont struggle to go 55 on the highway
 
#14 ·
Dead on. The freeway is the issue, but if you regear... then you will want bigger tires to bring the RPM's down. I am running 4:88's, and I am going to put 35's on my 4. This will put me around 2600 RPM at 70... I think... I have also heard ...(I think it was Tom Woods web site) that you don't need a SYE until you go over 4", but some have had different experiences.

nahh not really, u may get 2 HP from each one of those things, but they will all cost about $100 so ur looking at $100 a horse, not worth it in my opinion, its better to regear to lower gears so your in the peak HP band then to gain 4-5 hp
X2.... total waste of money and time. Don't bother. Higher octane is probably a better investment. Although, I put a K&N in mine. Funny thing is when I purchased my Jeep (used) it had a piece of foam taped to the air filter which was sufficating the engine. Not sure why anyone would do that.
 
#10 ·
Thanks for all the input. I'm not looking to build a rock crawler, just something that can navigate over some of the random larger rocks on these NH trails, and look bad ass in the process. I think a 2-3" lift, with a 1" body lift and some armor is definitely in order to start... back in my youth I used to had a ricer (accord) with a four banger in it, and I noticed a considerable gain in ponies from intake/header/exhaust upgrades- is this a worth while option four the 2.4L to gain a bit more power?
 
#13 ·
I have been thinking about rebuilding a 4 banger only with higher compression so that I could utilize E85. E85 actually runs very well in a high compression engine and in the case of a few XJ owners from Brazil who got 4.0L factory export engines which run 11:1 they get about 30mpg with their ethanol engines. The downside is that once you up to that compression ratio gone are the days of running regular gas, you now need 97+ octane if you put gas in.
I also like that 4BT conversion that was done but if diesel keeps climbing the numbers keep getting worse.
 
#15 · (Edited)
Higher octane does NOTHING on regular stock natural aspiration engines.

Take pics of the foam. If i'm correct it was probably put on there to try to clean the air more.

K&N is trash. K&N is trash. Get it?. K&N is trash.
It lets more dirt in than it filters. It's got very big holes compared to what a filter should have to do its job efficiently. While you're at it put a fly net on there so at least you get unrestricted air lol.
 
#22 ·
OK... so your real passionate about this issue. Now logic seems to dictate that if you put foam in front of the air cleaner, it stops the engine breathing. Now I could keep the engine real clean if I just stopped up all the air, but that is not really my objective. So I have a K&N which seems to get pretty good press everywhere else. (What do you have). What evidence do you have for the repeated claim X3 (I got it :) ) that K&N is [did you say] "Trash". BTW my Jeep ran much better after making the change from packing foam to K&N. :cool:


You will get worse mileage on a low compression engine with high octane fuel which is what the auto industry has built for the market since the 70's. thats why those 'e85 dual fuel' engines are such a joke. E85 works well in high compression, just look at alky dragsters for an example.
Well if that is the case maybe I will save myself some money. How do you know this is true? Any objective evidence. :D

Gilez; erickpl,

While on the topic, I also plan a small build for my four banger which would be Rusty's 2" Springs, OME Shocks, RE Discos, and vital armor. I plan to run 31 inch tires and eventually a limited slip in back and ARB up front which is plenty to get me through the trails I want to ride and maintain 20+ mpg. My concern isn't primarily the complete lack of durability of the Dana 35, with my anemic four banger and close to stock tire plan.

Its the AX-5. Anyone with some feedback on the trans?...I may post this somewhere else, however I was looking at a Dana 300 transfer case on craigslist in my area as an upgrade for the np231 and came across some depressing info looking for a conversion kit. Problem is the AX-5 is its basically a car tranny, which I don't want in an offroad truck. However is has been used successfully as a truck tranny in the Jeep and Toyota markets.

SO before I go commit myself to my little four banger, what about the AX-5?...How much of a weak link is it?

You guys both have some real bad ass trucks by the way.
I still have the stock trans setup. I am waiting for it to break before upgrading, so I have the same questions you do. :)
 
#17 ·
I have 33's, 4.88's, Yukon 35 rear axle, ARB rear, Lockright front. For around town, I LOVE IT! On the trails, I LOVE IT. The only place I have an issue is on the highway. I can hold 70-75 with no problem, but a long gradual grade or a short steep one will have me downshifting. I find I downshift less with 4.88 and 33's than I did with 4.10's and 30's.

For a weekend wheeler and casual trails (with the occasional hard ones thrown in), it is a very nice option.

Here's mine.





If you wanted to replace the engine, you'll be doing the transmission and def the rear axle at a minimum. A V8 or strong V6 would likely grenade the transmission and D35 in short order. I'm not going to debate the D35 merits or whether or not it is a turd. In my application with a 2.5L, the upgraded Yukon 35 shafts have been wonderful for me with the ARB in back.

My logic for the 4 was that the lower price point allowed me some extra budget room for some of the mods I've done - some cosmetic, most capability enhancements.
 
#18 · (Edited)
Gilez; erickpl,

While on the topic, I also plan a small build for my four banger which would be Rusty's 2" Springs, OME Shocks, RE Discos, and vital armor. I plan to run 31 inch tires and eventually a limited slip in back and ARB up front which is plenty to get me through the trails I want to ride and maintain 20+ mpg. My concern isn't primarily the complete lack of durability of the Dana 35, with my anemic four banger and close to stock tire plan.

Its the AX-5. Anyone with some feedback on the trans?...I may post this somewhere else, however I was looking at a Dana 300 transfer case on craigslist in my area as an upgrade for the np231 and came across some depressing info looking for a conversion kit. Problem is the AX-5 is its basically a car tranny, which I don't want in an offroad truck. However is has been used successfully as a truck tranny in the Jeep and Toyota markets.

SO before I go commit myself to my little four banger, what about the AX-5?...How much of a weak link is it?

You guys both have some real bad ass trucks by the way.
 
#21 ·
not meant at anyone in particular. just notice a lot of people think the 2.5 is so underpowered it isn't drivable. I can do 70 on the highway @ less than 3k rpms on 30x9.50 MT's. (it's an auto)
I really don't care to go faster than that in a wrangler. I just got back from a trip to bama. the hills didn't bother me, i got right at 17mpg on the trip and 275 miles only took me 4 1/2 hrs.
 
#28 ·
I know nothing about octane other than what the average joe knows. Higher octane .... higher performance. It seems that I get better performance with the 89. Don't really care about gas milage... (global warming is a hoax). :rolleyes:

I will certainly check out the inside of the tube, but maybe I should have clarified. I do not have a CAI. I just have the drop in K&N brand filter. Does that make a difference to the theory???

Thanks for the education. Again this forum has been very helpful.
 
#35 ·
I have a 4cyl and i dont have an problems.... yet?!?!?!? lol woot woot
 
#42 ·
I have built my 4 cylinder. So I would vote to go for it. My 4 does great.

Did anyone ever considered that the very greenhouse gasses that the global warming hoax is complaining about (Co2) is what the trees need to live. Global warming is an attempt (maybe sucessful) for liberals to take control of governement and big business and regulate the crap out of it.

:bottom::bottom::bottom::bottom: Bad Liberals ... get an education. Read Adam Smith "Wealth of Nations.

End of Rant... :wavey:
 
#44 ·
I have built my 4 cylinder. So I would vote to go for it. My 4 does great.

Did anyone ever considered that the very greenhouse gasses that the global warming hoax is complaining about (Co2) is what the trees need to live. Global warming is an attempt (maybe sucessful) for liberals to take control of governement and big business and regulate the crap out of it.

:bottom::bottom::bottom::bottom: Bad Liberals ... get an education. Read Adam Smith "Wealth of Nations.
x2

End of my rant. um.... Thread un-hijacked
 
#48 ·
You're right Gilez. Trees need CO2 to live however, we are cutting many of those down too :) Its the basic circle of life..animal life produces co2, plants need co2 to breathe and produce oxygen.. it just keeps turning. One needs the other to live. Well what happens to the circle when we're cutting all the trees that convert the CO2 to oxygen down? Also what happens to the CO2 level?
We legally have to plant more trees than we cut down, and we do. Damn liberals and their brainwashing propaganda. The trees are fine, theres plenty of them. Even my woodshop teacher/boss is an environmentalist! as he says "I bless the tree before I chop it down. HEYAHHH!:firedevil:"
 
#51 ·
Yea, I hate this global warming, it cost me an extra $500 to heat the house this year, electric house, my KW use was way up...not to mention the extra 40 gallons of kerosene for my shop heater.Not to mention all the good snow storm missed us this year, either passed north or south of us, dam...


I like the 4, easy to handle, easy to move around and won't give an engine stand a hernia like the 6 does or moving the head from the engine to the work bench. I wish there was more information on really building them with some good bullet proof models. I know a guy in either norway or sweden that put a supercharger on his 4 banger YJ with good results, no insane boost either, I seem to remember he went with 5 or 6 lbs of boost and got outstanding performance from it.
 
#54 ·
richp said:
Yea, I hate this global warming, it cost me an extra $500 to heat the house this year, electric house, my KW use was way up...not to mention the extra 40 gallons of kerosene for my shop heater.Not to mention all the good snow storm missed us this year, either passed north or south of us, dam...

I like the 4, easy to handle, easy to move around and won't give an engine stand a hernia like the 6 does or moving the head from the engine to the work bench. I wish there was more information on really building them with some good bullet proof models. I know a guy in either norway or sweden that put a supercharger on his 4 banger YJ with good results, no insane boost either, I seem to remember he went with 5 or 6 lbs of boost and got outstanding performance from it.
Sorry I have to quote someone to post.
Jeepers are the only ones I seen complain about small engine size. I had Toyotas before they did very well. A Sami has a 1.3 liter and gets around very well. Here is what I have noticed with mainstream Jeepers they want to take everything and the kitchen sink. I weighted my tj full tank and it was 2980# I meet a guy same model his 5250# that's a big weight difference. Yes he did have a pull out table to cook on and yes he had enough water to shower too. He did complain about fuel use and being sluggish while mine was packed also with drinks and food just hopped around like a happy little bunny his growls and moaned. So it's really how you use it. Keep it at 60% to 80% of the gross vehicle weight rating and it drive better and u be less comfortable. In the marine corp we had a saying breeze during the day and freeze during the night. Breeze and freeze for short. Well that my two cents anyway.
 
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