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$1600 for 20HP is hard to stomach lol I'd just gut the cats, and make a 3" exhaust. I've been trying to find a high flowing muffler that isn't obnoxius like my current chambered Thrush. Think I'm going to go with the Borla Pro XS. What muffler are you running?
 
20 hp . . . . . at what rpm ? Skeptical . . . . . very!
Anyone concerned with torque ?
Where the torque curve starts, if it's smooth and fat, where it drops off ?

Can't get HP gains without TQ gains. It's generally always a flat TQ curve on the 4.0, and you're only going to get gains like that with boost.
 
At the end of the day you might consider a Magnum swap. Could be a better solution all around for that much money especially considering engine work and forced induction on the 4.0.
 
At the end of the day you might consider a Magnum swap. Could be a better solution all around for that much money especially considering engine work and forced induction on the 4.0.

No way I would put a Magnum V8 in it. I drove a LJ with a Magnum swap in it. Those engines flat out suck if you ask me (just my opinion). Didn't have anywhere near the power I was expecting, and for the time and money spent, I would just as soon swap in a 5.3.

The supercharger doesn't require anymore than 4-5 hours to install it tops, that's it. Way less work than a Magnum swap.
 
At some point I had intended to do all of this. I spoke with Charles and he said the supercharger will go to 25 psi and still remain efficient. However, in order to go past 11 psi, he said I'll need ARP head studs and forged pistons (I think the compression on the 4.0 is already low enough actually). At that point it wouldn't be a bad idea to do some other internal work as well.

Here's his supercharger on a Golen 4.6 stroker:

He said they've got one making 570 crank horsepower with the Golen 4.6 stroker and his supercharger running 20 something psi.

Can you believe that? 570 horsepower out of a 4.0... sheesh.

Just sounded a bit like you were considering bottom end work too. I can understand the bolt on angle. I don't really know what you mean by 5.3 vs Magnum, I don't know much about all the variations. Most people who have done this seem to recommend the 5.9 Magnum. If you didn't like the Magnum (might have been a 5.2) in an LJ I'd be careful about spending lots of money on forced induction, similar power to the Magnum you drove and more weight to haul around.
 
Just sounded a bit like you were considering bottom end work too. I can understand the bolt on angle. I don't really know what you mean by 5.3 vs Magnum, I don't know much about all the variations. Most people who have done this seem to recommend the 5.9 Magnum. If you didn't like the Magnum (might have been a 5.2) in an LJ I'd be careful about spending lots of money on forced induction, similar power to the Magnum you drove and more weight to haul around.

It was a 5.9 Magnum I drove.

This will be my second forced induction 4.0. My last one was a blast to drive and had gobs of power. Many others such as Blaine, @RubiconMike, and others can back me up on this. A properly done forced induction system on a 4.0 will put down just as much power (if not more) than most of the lower level V8 engines, with the exception of perhaps higher model LS engines, and of course Hemi engines.

They also retain the best part about the 4.0... the low end torque, which is something a lot of the V8 engines don't have as much of down low.
 
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It was a 5.9 Magnum I drove.

This will be my second forced induction 4.0. My last one was a blast to drive and had gobs of power. Many others such as Blaine, @RubiconMike, and others can back me up on this. A properly done forced induction system on a 4.0 will put down just as much power (if not more) than most of the lower level V8 engines, with the exception of perhaps higher model LS engines, and of course Hemi engines.

They also retain the best part about the 4.0... the low end torque, which is something a lot of the V8 engines don't have as much of down low.

Agreed.

I went with the Banks turbo system - for around $5k you get about 50% more hp, and more torque at 1,600 rpm than the stock motor makes at max. I was able to install it by myself with basic hand tools over a weekend, and it's smog-legal in California. The 4.0 is extremely reliable in stock form, so applying a moderate amount of boost (5 ~ 7 lbs) will not turn it into a hand grenade. It drives just as smoothly and reliably as a stock motor, just with a lot more power.

In theory, a supercharger should have better low-end torque, since it is mechanically driven and doesn't have to wait for the turbo to spool up. I looked at superchargers but didn't find any that were California approved, so that wouldn't work for me (apparently Sprintex got their certification in 2016, but that was years later and they don't have an intercooler, which I think is critical for a forced-air system).

I looked at engine swaps, but I've done them in the past and it's a considerable amount of time and effort, and in California you then have to go to the DMV to have it certified. Maybe if I still had a shop where I could let it sit in the corner for a week or three I might consider it, but that's no longer an option for me. I was considering the GM 5.3, which a a modern design and there are thousands in the junkyards - even an aluminum block version. On the other hand the Magnum 5.9 is, I believe, an updated version of the old Chrysler 360 - a good engine in the '70s but rather outdated by comparison to the GM LS series of engines. I think the new Chrysler "hemi" is a much better choice if you want to stay within the Chrysler family.

There are several ways to get more power in a TJ, and no one of them is the"right" way. I chose the turbo for the reasons above, others chose different paths that fit their needs better. I encourage others to get as much information as they can, and make their decision based on their personal needs and wants.
 
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Agreed.

I went with the Banks turbo system - for around $5k you get about 50% more hp, and more torque at 1,600 rpm than the stock motor makes at max. I was able to install it by myself with basic hand tools over a weekend, and it's smog-legal in California. The 4.0 is extremely reliable in stock form, so applying a moderate amount of boost (5 ~ 7 lbs) will not turn it into a hand grenade. It drives just as smoothly and reliably as a stock motor, just with a lot more power.

In theory, a supercharger should have better low-end torque, since it is mechanically driven and doesn't have to wait for the turbo to spool up. I looked at superchargers but didn't find any that were California approved, so that wouldn't work for me (apparently Sprintex got their certification in 2016, but that was years later and they don't have an intercooler, which I think is critical for a forced-air system).

I looked at engine swaps, but I've done them in the past and it's a considerable amount of time and effort, and in California you then have to go to the DMV to have it certified. Maybe if I still had a shop where I could let it sit in the corner for a week or three I might consider it, but that's no longer an option for me. I was considering the GM 5.3, which a a modern design and there are thousands in the junkyards - even an aluminum block version. On the other hand the Magnum 5.9 is, I believe, an updated version of the old Chrysler 360 - a good engine in the '70s but rather outdated by comparison to the GM LS series of engines. I think the new Chrysler "hemi" is a much better choice if you want to stay within the Chrysler family.

There are several ways to get more power in a TJ, and no one of them is the"right" way. I chose the turbo for the reasons above, others chose different paths that fit their needs better. I encourage others to get as much information as they can, and make their decision based on their personal needs and wants.

I think one of the biggest things to consider with the V8 swap is that the majority of them don't have the power down low that the 4.0 has. They require being revved a bit higher to make power. While this isn't necessarily an issue, if you like to do any off-roading, the almost instant torque of the 4.0 is actually very ideal for off-road situations, where you don't have the ability to rev the engine a lot higher to make power.

Here's what it comes down to for me: If I was going to put in a V8, I would put in a GM V8, no doubt. The Magnum engine is simply an outdated engine IMHO, and the aftermarket support isn't anywhere near what it is for the GM engines. There is so much support for GM engines that there is a reason they are the most commonly swapped engine in any vehicle, not just Jeeps.

The Hemi engines are nice (the newer ones), but very costly. In addition, they still don't have that same level of aftermarket support that GM engines do. They're also not as cheap when it comes to parts.

Anyways, just my opinion here. I don't mean to offend anyone who has a Magnum swap. I'm just saying I wouldn't put one of those Magnum engines in my TJ if you paid me. I'd rather keep my 4.0 any day over one of those.
 
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The Hemi engines are nice (the newer ones), but very costly.

Yeah, a guy in a local club here had a hemi installed by a shop - total "turn-key", he dropped it off, they did the full install and got it CA smog certified. - $12,000.

Really nice result, but geeze, $12,000....
 
Yeah, a guy in a local club here had a hemi installed by a shop - total "turn-key", he dropped it off, they did the full install and got it CA smog certified. - $12,000.

Really nice result, but geeze, $12,000....

That's actually a shockingly good cost. I'm guessing it's a manual transmission though and they were able to use his stock transmission? That cuts down on cost quite a bit.