This is my second YJ. They are awesome! But I want more power out of this 2.5l 4 cyl. Any suggestions? As far as I can tell it looks completely stock. What kind of air intake or other small mods can I do to get a little more power. Thanks.
How can I get more power out of my 4 cylinder Jeep?
- Thread starter ChristianM
- Start date
The only way you're going to get more power out of that is to re-gear it (as deep as possible), put a turbo or supercharger on it, or swap it out with a V8 (or similar).
No exhaust, cold air intake, or anything else is going to give you any sort of measurable power gains. That being said, prepare to drop a lot of money if you want some serious power gains
4 cylinder Jeeps are good for two things, driving off-road and cruising around town.
When it comes to highway speeds or any sort of sustained speeds, forget about it
No exhaust, cold air intake, or anything else is going to give you any sort of measurable power gains. That being said, prepare to drop a lot of money if you want some serious power gains
4 cylinder Jeeps are good for two things, driving off-road and cruising around town.
When it comes to highway speeds or any sort of sustained speeds, forget about it
Flyer58
YJ Enthusiast
I've always read the AX-5 transmission and axles are ther weak spots so more power might break them. I don't know since I just use mine for grocery shopping 
I've always read the AX-5 transmission and axles are ther weak spots so more power might break them. I don't know since I just use mine for grocery shopping
You're actually right about that. The AX-5 is a considerably weaker transmission (in comparison to the AX-15). So if you were to turbo or supercharger your 4 cylinder, you might potentially be in for some bad surprises with the transmission (depending on how you drive it).
When you start looking at dollar per horsepower numbers, it becomes painfully apparent that if you really want more power out of your 4 cylinder, you're going to need to spend upwards of several thousand dollars, and probably even more depending on how serious you are.
For this reason I think it's best to accept these things for what they are. Great off-roaders, good around town cruisers, but not the best in terms of long road trips or extended high speed highway travel.
The JKs and JLs fix this with their longer wheelbase, powerful engine, and SUV like ride, but that's like comparing apples and oranges.
AJeepMemory
New Member
Maybe an Electric Turbo? I cant find any good turbo kits for these. I am looking for one on my jeep too
No such thing. Not yet at least. Jaguar and other high end auto manufacturers are working on these for OEM applications, but there is none available aftermarket.
Jimmyj1387
New Member
That's about all you can do. Use it for it's intended purpose, and if you really want more power, either forced induction or an engine swap, the latter being the better choice.
smgager
Member
There is an outfit out there that sells a 2.9 stroker for about $3K, but all I have seen are negative reviews about their customer service, can't remember their name. I'd look at a swap before dropping that much coin an 4 banger.
On a cheaper note, going to an electric fan will buy you about 5-7 more HP, plus you can turn it off when you're on the highway and don't need it...Just a thought.
On a cheaper note, going to an electric fan will buy you about 5-7 more HP, plus you can turn it off when you're on the highway and don't need it...Just a thought.
505 Performance. I have pretty much only seen bad reviews from them. I'd engine swap before I'd install their stuff.
As for the electric fan....I and many others don't consider that to be a good idea. The aftermarket fans never provide anywhere close to the CFM volume of the stock mechanical fan...whether what they do provide is "good enough" or not, is debatable depending on climate. In Texas, that crap doesn't usually work. They also don't provide any extra HP unless they flow less. If they were to flow the same amount of air as stock, they would suck that same load out of the engine via the alternator. So the HP maybe gained is really just a result of flowing less air. The only benefit I could see would be maybe for water crossings which most folks don't ever do. On the highway, the clutch fan will even disengage a lot of the time as it can sometimes "feel" the cooler temps provided by the extra air on the highway and disengage to a point where it's not really sucking much power.
If I were to go with an electric fan it would be an OEM solution like from a Taurus. Even so, they will flow enough CFM that it takes a lot of power out of the engine electrically to provide that through the alternator. Then you're taxing the electrical system pretty hard as well. I'd rather have that load direct on the engine than through the stock 75A or 90A alternator. So at that point to me, it makes more sense to just keep it stock still.
Regearing deep for the tires is the much more reasonable solution overall, as well as expecting reasonable results from a 125 HP 4,000 lb box shaped vehicle.
Not exactly true. And most electric fans are kits that are put together by the buyer and often are always faced with constant issues.
On another note, the 2.4L 4 cylinder in the late model TJ’s use an electric fan setup from the factory and seem to work great. Something about having true engineers behind the design seems to make it more reliable than throwing something together with aftermarket parts.
There are, but they don't function full time like a normal turbo charger, but rather for occasional boosts of power. And spendy.
I'm re-gearing too, but I've always had an electric fan and it helps a little.
Here in AZ, I wheeled a flat-fender with a 175hp pinto in the summer.
it never got hot, ever.
I just put an electric on my YJ to just get rid of the propeller and the fan shroud that takes half the engine bay.
Here in AZ, I wheeled a flat-fender with a 175hp pinto in the summer.
it never got hot, ever.
I just put an electric on my YJ to just get rid of the propeller and the fan shroud that takes half the engine bay.
Im having the same issue every 2.5l YJ owner has. Ive found a company near me that will assist in a motor swap and was considering the straight 6. any thoughts. If im swapping should I just go all out ( go big or go home ) or would a 6 cylinder swap be worth the cost and time?
Depends. It’s a lot of work and money to gather up all the stuff for the results netted. However if you can do a lot of the work yourself, it’s certainly an easier swap than a V8 or something else because besides frame welding, it would be a mostly plug and play swap using almost all stock parts. And the 4.0 does make decent power, nothing that will blow your mind over but with proper gearing for the tires, a 4.0 can certainly get the job done more than adequately.
the problem with V8 swaps in YJs is that there is no simple swap. Every single option has things you have to figure out and work around. So unless you’re really creative, they can be tricky. It would be awesome to sport a decent V8 in a YJ though, that is for sure. I’d love to do a Mopar 5.2 or 5.9 with an AX15 someday. Ripping around town would be a blast.
the problem with V8 swaps in YJs is that there is no simple swap. Every single option has things you have to figure out and work around. So unless you’re really creative, they can be tricky. It would be awesome to sport a decent V8 in a YJ though, that is for sure. I’d love to do a Mopar 5.2 or 5.9 with an AX15 someday. Ripping around town would be a blast.
In my experience, Jeeps are All about gears, the lower the better though their are reasonable limits.
Re-gearing axles helps on the street, especially with a 4 banger, deep reduction trannies make all the difference Off-road.
Been considering a swap myself, but out of frustration more than anything else.
Though I haven't really driven mine enough to have any complaints about power.
I've got a little 175 horse 2.0 Pinto married to a SM420 from my old trusty steed. (what can I say, I like 4 bangers)
But it's carbureted, and I'm just about sure I don't want the hassle of a swap.
Would be other complications, I fabbed the bell housing specifically for a RH drop t-case, relocating the starter to the driver side.
That, and it's got a mechanical clutch.
For now I'll just stick with the 2.5.
Re-gearing axles helps on the street, especially with a 4 banger, deep reduction trannies make all the difference Off-road.
Been considering a swap myself, but out of frustration more than anything else.
Though I haven't really driven mine enough to have any complaints about power.
I've got a little 175 horse 2.0 Pinto married to a SM420 from my old trusty steed. (what can I say, I like 4 bangers)
But it's carbureted, and I'm just about sure I don't want the hassle of a swap.
Would be other complications, I fabbed the bell housing specifically for a RH drop t-case, relocating the starter to the driver side.
That, and it's got a mechanical clutch.
For now I'll just stick with the 2.5.
Yeah I always suggest a regear no matter what engine you’re sporting. A 2.5 should pretty much only have 4.88 or 5.13 and nothing else. Worst case you regear it and still want more power, well then at that point you upgrade the engine and have a blast on the new gears with the new engine.