Has anyone swap a 2.5 throttle body to a 4.0 throttle body what needs to be done and what can I do to squeeze more power out of my 2.5. What about injectors any thoughts on them im about to hit 200k miles and I think they are still stock
2.5 throttle body to 4.0 throttle body
- Thread starter Tinytim14
- Start date
Performance mods will do nothing significant for your 2.5. Spend your money on regular maintenance. Save up for a 4.0 if you want more power. At 200k I'd be treating my engine like a grandmother at a retirement home and not like a stripper.
The throttle body is a direct swap, you will need to switch out the 2.5 sensors to the 4.0 TB and get a new gasket otherwise it will bolt and connect up the same. The swap will get your butt dyno moving but not help our 2.5's. Swapping out the injectors is not a bad thing considering the age but it's likely new O rings will be responsible for any improvement. I had a bad injector #3 on my 2.5 so I swapped in the 4 hole injectors and she idles like a swiss watch.
http://www.fourwheeler.com/how-to/engine/154-1301-dethrottled/
OP
If she breaks v8 time wife said have to break before upgrade and in 2015 it had new pistions and heads a full rebuild besides the cam and fuel stuff
OP
Just stay close to your year and you will be fine, there are plenty out there. The earlier years are slightly different.
It won’t make any difference at all, guaranteed.
The only way it would make a difference is if you ported your head, port matched the intake manifold, and did something like bigger valves and a long tube header.
It’s not as simple as bolting on a bigger throttle body. Sorry, but that’s just a myth.
Talk to any performance engine builder if you don’t believe me.
The only way it would make a difference is if you ported your head, port matched the intake manifold, and did something like bigger valves and a long tube header.
It’s not as simple as bolting on a bigger throttle body. Sorry, but that’s just a myth.
Talk to any performance engine builder if you don’t believe me.
OP
I was planing on a spacer plus a power chip new headers and the TB also 4 port injectors. You really think nothing will change at all
John Scoggins
TJ Enthusiast
Installing the 4.0 throttle body won't do a thing for performance. Zip, nada, nothing. The stock 2.5 throttle body easily flows more air than the engine can pull at wide-open throttle and redline rpms. It absolutely will not help. Really.
Same with the throttle body spacer, it will do absolutely nothing for performance. No matter what the claims are you'll find in the advertisement. Spacers can boost performance significantly when placed under a "wet" intake device like a carburetor or first-generation throttle body like the old TBI (throttle body injection) systems had. They passed a mixture of air & fuel down into the air intake manifold. Spacers helped that type of device. But the more modern air-only throttle body the TJ uses passes air only... no fuel passes from the throttle body. A spacer will do absolutely nothing to improve performance with the type of throttle body used in a TJ, JK, or JL.
Same with the injectors. The OE factory injectors can already in stock form flow more fuel than is needed. The upstream O2 sensor monitors the air/fuel ratio and once the correct amount of fuel has been sprayed into the combustion chamber the computer shuts the fuel injector off. If an aftermarket fuel injector could flow more fuel, the computer would just shut it off sooner to keep the correct air-fuel mixture.
The ONLY things that can produce more power are 1) regearing to a lower axle ratio when you have installed larger tires that reduce performance. Your problem is that you have installed 35" tires and your 4.88 gearing is not enough gear for that size tire with your 2.5L engine. The bigger problem is those 35" tires are too big for your Dana 35's carbon steel 27 spline axle shafts and sooner or later you're going to have a broken axle shaft. Guaranteed. I would reduce that tire size to 33" which the Dana 35 can handle so long as the axle remains open without a locker. Installing a Super 35 kit into your Dana 35 would make it strong enough for 35's but you'd still have the lower power issue caused by the 35" tires.
And 2) the second thing that can improve power would be to install a supercharger. That works. But you'd still have the issue of the 35's being too big of a tire for a stock Dana 35.
The bottom line is that 35's are too big for your 2.5L engine and Dana 35 rear axle. Drop down to a 33" size and lots of things will improve. Especially the odds your Dana 35 won't snap an axle shaft.
This is a friend of mine who snapped a rear Dana 35 axle shaft running 35's. I was with her and heard it snap, I had no idea she was running a Dana 35 or I would have "counseled" her against it.
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It's not that I don't think nothing will change at all, I KNOW nothing will change at all.
Throttle body spacers do not work on fuel injected vehicles. Read this article:
https://wranglertjforum.com/threads/do-throttle-body-spacers-work-on-jeep-wrangler-tjs.4509/
4-hole injectors are also a myth. A huge myth that was blown out of proportion by people who don't know anything. 4-hole injectors do absolutely nothing on these engines. I've run the stock injectors and 4-hole injectors, and I assure you it's nothing but a myth.
The idea of a larger throttle body adding more power is bogus because that would imply that the factory throttle body was a bottle neck to begin with (which it isn't).
Now if you wanted to get more power by forcing more air into the engine (which is the idea behind a bigger throttle body) you'd need to port and polish the cylinder head, get bigger valves, a full header, AND a bigger throttle body. Then you're allowing the engine to take in more air.
But with just a bigger throttle body, there is no way it's getting more air in, as everything else is still the same size.
The only way you will ever get more power out of that 4 cylinder is to turbocharge it, supercharge it, or spend a ton of money and have forged pistons put in, raised compression, a big valve head, headers, etc.
The bottom line is there is simply no way to get more power out of your engine without spending a considerable amount of money. Air intakes, throttle body spacers, injectors, and bigger throttle bodies will do nothing at all. It will literally be a waste of your money.
I'm not trying to be rude here, so please don't take it that way. I'm just trying to prevent you from wasting money on a lost cause.
If you really want more power, you need to be prepared to spend around 3-5k on a supercharger or turbo. That will give you power, but even at that point, I think you'd still be better off swapping in a V8 at that point.
If you're after more power, the cold hard truth of it is that the 4 cylinder is just a lousy engine to start with. It's great around town and on the trails, but it's never going to be good on the highway.
I have to take exception to calling our 2.5's a lousy engine as it does exactly what it was intended to do.
OP
N
No im not taking it bad at all I wanted more info before the money was spent and now that i know im stuck with a gutless pig till I get the money for a v8. Any thoughts on v8s though I love learning more about my jeep and how to make it more fun
OP
I had a full rebuild done I left it open to not break anything and I'm not going to lie its a road queen right now i know that the 35 is a time bomb thats why its being babied. I habe a dana 70 just sitting that im thinking about but that's big and the 2.5 can't do it so Idk
The easy answer is to install 33" tires. That'd be the perfect elegant (to use an engineering term) cure for both issues.
+1 ...and does it in a commendable fashion.
You may not like the 2.5's and 2.4's. You may think they are a waste of a good TJ You may look at SE drivers like we're stupid or backwards. Fine. I know better. At the very least, do what this forum is good for. Respect our choices.
(Sorry, that turned into a rant. I'm still leaving it here.)
You have 35's with 4.88 and the 2.5. 5.13 would have been the desired ratio but even then it isn't enough. Even if you could add 25% more HP, you'd still only have 150 HP, the same as the later 2.4, which isn't up to 35's on 4.88 either. It just is what it is.
Okay, just wanted to make sure my words weren't being misconstrued as aggressive or anything. There's just a lot of myths out there in terms of supposed "bolt-ons" for power gains, but the truth of it is that the only bolt-on you'll really gain power from is a turbo or supercharger.
A V8 swap is around $7,000-$20,000 depending on how you do it.
To do it on the cheaper end, that assumes you go with an engine such as the 5.3 Chevy engine (which are very, very common), pair it with a used AX-15 manual transmission (your stock AX-5 transmission won't handle the power of the V8), and do all the labor yourself.
Novak is the go to source for information regarding V8 swaps and what works well and what doesn't:
http://www.novak-adapt.com
They also sell all of the conversion pieces you need, even 100% plug-and-play wiring harnesses.
It's a big project for sure, but you'd be more than happy with the results.
OP
Dang a Dana 70 rear and Dana 60 front? How big of a V-8 are you planning on putting in that thing? What size tire and for what kind of wheeling? I'm only asking because I was there once. What engine & drivetrain? What type of Dana 60 are you looking for?
I ahve a 1997 SE TJ.
The best mods you can do for your 2.5 is to lose as much weight as possible on your Jeep. I had 4.88 gears in mine also and went from 33" tires to 35" tires and sure wished I'd stayed with the 33"s.
I ahve a 1997 SE TJ.
The best mods you can do for your 2.5 is to lose as much weight as possible on your Jeep. I had 4.88 gears in mine also and went from 33" tires to 35" tires and sure wished I'd stayed with the 33"s.