3.8 engine mods
05-01-2014 | 08:14 AM
#22
Thread Starter
JK Newbie
Joined: Apr 2014
Posts: 64
Likes: 0
From: Olathe, KS
I have considered modding a 3.8 as well. Most if not all say its a waste. I have built Oldsmobile and Pontiac V8's so I am used to everyone telling me what I am doing is a waste of time. As far as parts, Hesco supposedly makes a camshaft. A coil is available as well. Personally If you are looking for a mild upgrade, I would do Ripp headers and intake. I would use their programmer and sale your tuner to get some of the money back. You will be out $2k and have about 25 or so hp extra at the wheels. For some reason parasitic loss in Jeeps seems high, so finding someone to tune transmissions and or possibly a converter swap might be a better route to help get some of this back (if you have an auto). As far as my own project, I am looking at getting a spare 3.8 and building it and the installing it into my Jeep. It's hard to bring myself to do anything to it as I have the extended warranty. I am wanting to install Hesco's stroker kit and a Ripp black ops SC. This along with RIPP headers and a cat back. I am considering having heads and lower intake extrude honed and very mild port work (very mild, more emphasis on a good valve job). Also considered having A set of valves made to help with low lift flow without doing a lot of port work. I would like to see what differences a good valve job and balancing and blueprint would do for one of these engines.
I’m not saying Planman doesn’t know what he’s talking about at all. That’s a great part list he has. Do I thing you need all that? No… I’m not saying you shouldn’t have it either. I know with my 03, I didn’t keep the AC, but as far as the alternator and power steeling, I used the stock LT1 parts, I even kept the stock Jeep radiator, but I always wanted a bigger and better one. As far as mounts goes… I did buy a bell housing mount, but I fabricated other way to make things fit. The rear transmission mount only needed to be moved a few inches and drilling some new holes or welding something wasn’t a big issue to me either. I put a 302 in an 82 Mazda RX7 and a 327 in a 78 Land Cruiser without buying anything. Was that the smart way of doing it? No. lol
I would say if you’re going to do it right, Planmans is the better way to go, if you’re on a budget, there are cheaper ways of doing it, but this wasn’t meant to be about engine swaps or even supercharging. Those are the obvious ways of adding power to the Jeep. It was about adding power to the 3.8, the little things that can be done like upgrading to a different intake (like a fast intakes for the LS) or larger roller rockers, or the Viper throttle body. Does Headman or Hooker make headers for the 3.8? Does Edelbrock make heads or an intake for the Jeep? Is there any company that does? Can we port out the intake and heads to make a little more power? Does anyone make a stroker kit for these engines?
05-01-2014 | 08:15 AM
#23
Thread Starter
JK Newbie
Joined: Apr 2014
Posts: 64
Likes: 0
From: Olathe, KS
I think a new set of gears in a great Idea and it surely needs done on mine. I’m running 35’s on the stock gears. Do they make a 3.73 for the Jeep JK? I don’t want to go to low. I don’t want to kill my MPG’s. I would think a 3.73 or 4.10 might even help my MPG’s or get me back closer to stock MPG’s?!?
What do you think?
What do you think?
05-01-2014 | 08:29 AM
#24
JK Freak
Joined: Dec 2012
Posts: 625
Likes: 1
From: California
I've got a 2010 jkus on 33"s and have a superchips flashpaq. Iv been running gas saver mode but recently started filling up with 91 octane and set it to perfomance 91. It is like night and day for me. It's a seat of the pants diagnosis but regardless, it is definitely noticeable. Iv been pleasantly surprised and actually am content with it's power and acceleration now. Ya 91 octane costs a bit more but im hoping the increase in burn efficiency will result in slightly better mpg's, (As well as a cleaner engine long-term), at least enough to offset the price of 87 vs 91. Either way, a full tank of 91 is less than $3.50 more on avg.
05-01-2014 | 08:49 AM
#25
Thread Starter
JK Newbie
Joined: Apr 2014
Posts: 64
Likes: 0
From: Olathe, KS
I've got a 2010 jkus on 33"s and have a superchips flashpaq. Iv been running gas saver mode but recently started filling up with 91 octane and set it to perfomance 91. It is like night and day for me. It's a seat of the pants diagnosis but regardless, it is definitely noticeable. Iv been pleasantly surprised and actually am content with it's power and acceleration now. Ya 91 octane costs a bit more but im hoping the increase in burn efficiency will result in slightly better mpg's, (As well as a cleaner engine long-term), at least enough to offset the price of 87 vs 91. Either way, a full tank of 91 is less than $3.50 more on avg.
I added a Hypertech a week ago. I can't say that I feel much difference, but I'm hoping when I go fill it up again I will notice the difference. With my 35" and stock gears I'm getting right at 14 mpg's in town. I'm hoping it will bring me up to 16 or 17 mpg's. ( hoping )
I did check out Hesco and they do offer a cam for around $400 and a stoker kit for about $3K. Which just means a Ripp Supercharge kit is still the best route to go. Much less work adding a supercharger then a bottom end on your motor. IMO Plus Hesco didn't offer any HP numbers on the cam install or their stroker kit. Ripp has lots of dyno runs on youtube.
Hesco info:
HES38SK 3.8L STROKER KIT | Hesco
05-01-2014 | 09:28 AM
#26
JK Super Freak
Joined: Oct 2013
Posts: 1,474
Likes: 2
From: Where Ever the Corps puts me
I added a Hypertech a week ago. I can't say that I feel much difference, but I'm hoping when I go fill it up again I will notice the difference. With my 35" and stock gears I'm getting right at 14 mpg's in town. I'm hoping it will bring me up to 16 or 17 mpg's. ( hoping ) I did check out Hesco and they do offer a cam for around $400 and a stoker kit for about $3K. Which just means a Ripp Supercharge kit is still the best route to go. Much less work adding a supercharger then a bottom end on your motor. IMO Plus Hesco didn't offer any HP numbers on the cam install or their stroker kit. Ripp has lots of dyno runs on youtube. Hesco info: HES38SK 3.8L STROKER KIT | Hesco
05-01-2014 | 09:34 AM
#27
Forum Tech Advisor
Joined: Jan 2008
Posts: 1,208
Likes: 7
From: Billings, MT
I think a new set of gears in a great Idea and it surely needs done on mine. I’m running 35’s on the stock gears. Do they make a 3.73 for the Jeep JK? I don’t want to go to low. I don’t want to kill my MPG’s. I would think a 3.73 or 4.10 might even help my MPG’s or get me back closer to stock MPG’s?!?
What do you think?
What do you think?
This engine needs to turn at least 2500 rpm at that speed to operate efficiently.
4.10s with larger than 32s would be a waste of money for a 6 speed.
Here are the horsepower and torque curves for the 3.8L:
05-01-2014 | 11:10 AM
#28
Thread Starter
JK Newbie
Joined: Apr 2014
Posts: 64
Likes: 0
From: Olathe, KS
15 city – 19 highway according to Edmunds.
2500 rpm seems high… Not saying it is… It just seems that way… I’ve been shifting mine at around 2500 rpm’s and cruising it at 1500 rpm’s. Again use to my LS motors where in 6th gear at 80 mph I’m only doing 1800 rpm. Most people don’t believe the Corvette and Trans Am got good mpgs but it wasn’t uncommon for me to see 28 mpg’s out of my V8’s. (Apples and oranges I know)
I know we are talking about a lot more hp and torque, and torque curves that are completely different. I’m just saying that’s what I’m use too. I guess I should get use to other things huh?!?!? lolol I guess I wasn’t far off stock without the Hypertech, (14 mpg) Maybe with the Hypertech I will be over stock ratings? ;-)
I haven’t driven it on the highway much yet, I don’t have drill until the 16th. That’s when I will figure out my highway mpg’s.
What’s the difference between the Hypertech 52001 and the 52501?
2500 rpm seems high… Not saying it is… It just seems that way… I’ve been shifting mine at around 2500 rpm’s and cruising it at 1500 rpm’s. Again use to my LS motors where in 6th gear at 80 mph I’m only doing 1800 rpm. Most people don’t believe the Corvette and Trans Am got good mpgs but it wasn’t uncommon for me to see 28 mpg’s out of my V8’s. (Apples and oranges I know)
I know we are talking about a lot more hp and torque, and torque curves that are completely different. I’m just saying that’s what I’m use too. I guess I should get use to other things huh?!?!? lolol I guess I wasn’t far off stock without the Hypertech, (14 mpg) Maybe with the Hypertech I will be over stock ratings? ;-)
I haven’t driven it on the highway much yet, I don’t have drill until the 16th. That’s when I will figure out my highway mpg’s.
What’s the difference between the Hypertech 52001 and the 52501?
05-01-2014 | 11:17 AM
#29
Forum Tech Advisor
Joined: Jan 2008
Posts: 1,208
Likes: 7
From: Billings, MT
15 city – 19 highway according to Edmunds. 2500 rpm seems high… Not saying it is… It just seems that way… I’ve been shifting mine at around 2500 rpm’s and cruising it at 1500 rpm’s. Again use to my LS motors where in 6th gear at 80 mph I’m only doing 1800 rpm. Most people don’t believe the Corvette and Trans Am got good mpgs but it wasn’t uncommon for me to see 28 mpg’s out of my V8’s. (Apples and oranges I know) I know we are talking about a lot more hp and torque, and torque curves that are completely different. I’m just saying that’s what I’m use too. I guess I should get use to other things huh?!?!? lolol I guess I wasn’t far off stock without the Hypertech, (14 mpg) Maybe with the Hypertech I will be over stock ratings? ;-) I haven’t driven it on the highway much yet, I don’t have drill until the 16th. That’s when I will figure out my highway mpg’s. What’s the difference between the Hypertech 52001 and the 52501?
The 3.8L needs at least 2500 rpm.
It's kind of like the difference between a 600cc Japanese sport bike rpm and a Harley cruiser bike rpm.
05-01-2014 | 12:41 PM
#30
Thread Starter
JK Newbie
Joined: Apr 2014
Posts: 64
Likes: 0
From: Olathe, KS
I’m really not doubting you, this is truly just educational for me, and as I mentioned I know it was comparing apples to oranges.
I will say with the graph you show, the stock Jeep at 2500 rpm is at about 184 ft lbs. With the Hypertech it reaches 187 ft lbs. at about 1800 rpm’s, and again I’m not saying you are wrong. I’m just trying to get it right. Could that make a difference?
I have seen charts that say I’m with in specs but leaning on the sluggish side, and that 4.10’s are acceptable, and once you get into 4.88 and higher your highway use goes down. (For a 6 speed... Automatic was different) I just want to make sure I don't go too low.
I know I need to rid of my 3.21 gears
Last edited by SteveLNew; 05-01-2014 at 01:01 PM.