3.8L Engine Build
01-22-2011, 11:20 PM
#1
JK Freak
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I am thinking about getting an extra 3.8L from a wreckers to work on for fun,... maybe see how big a piston i can cram in, stroke it out, put in a decent cam, port and polish.,
the way these things seem to be dying it may not be a bad idea to have an extra one ready to rock and roll 100% better than the original.
I have never seen any performace engine parts for a 3.8L V6..
do they exist? who sells these parts?
the way these things seem to be dying it may not be a bad idea to have an extra one ready to rock and roll 100% better than the original.
I have never seen any performace engine parts for a 3.8L V6..
do they exist? who sells these parts?
Last edited by Jeep Hound; 02-01-2011 at 08:30 PM.
01-23-2011, 03:21 AM
#2
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3.8's are bored/stroked from factory (originally 3.3l) so the walls are thin already. They retuned from minivan specs for a better torque curve than the 4.0l inlines. I'm willing to bet this has a play in the reliability issues we're having. As far as better performance I believe there is not much that can be done mechanically. Maybe deck the heads to bump compression? But that kills even more reliability. Maybe rethink valve lift/duration? Otherwise I'm thinking retune fuel delivery, open the throttle body up, smooth air delivery altogether (cai), smooth exhaust (headers/catback) & basically just maximize efficiency in all subsystems.
It all seems sketchy to me because I am living proof of the horrible reliability of this engine design, 43k miles and the engine blew up. Regular oil changes and zero mods. It doesn't add up, unless of course you count the price of the engine, and labor to replace it, that I just got. :/
Nick
It all seems sketchy to me because I am living proof of the horrible reliability of this engine design, 43k miles and the engine blew up. Regular oil changes and zero mods. It doesn't add up, unless of course you count the price of the engine, and labor to replace it, that I just got. :/
Nick
01-23-2011, 06:16 AM
#4
JK Jedi Master
Consider getting a service manual to work from.
This is what I was able to find:
Cylinder Bore Diameter (Standard) 3.8L
3.7792-3.780 in.
Out of Round (Service Limits)
0.003 in.
Taper (Service Limits)
0.002 in.
Piston Diameter 3.8L-Measured 1.30" From Piston Top
3.778-3.779 in.
Clearance in Bore @ Size Location (New)
-0.0002–0.0015 in
Weight 3.8L
426 ± 5 grams
15.03 ± 0.1764 oz.
Ring Side Clearance
Top Compression Ring 3.8L
0.0012-0.0027 in.
Second Compression Ring 3.8L
0.0016-0.0033 in.
Oil Ring (Steel Ring)
0.0006-0.0089 in.
Side Clearance Wear Limit- Top Ring
0.004 in.
Side Clearance Wear Limit-2nd Ring
0.005 in.
Radial Wall Wear Limit Oil Ring Pack
0.0015 in.
Ring Width-Top Compression Ring 3.8L
0.0462-0.0468 in.
Ring Width-2nd Compression Ring 3.8L
0.0579-0.0587 in.
Ring Width-Oil Ring (Steel Rails) 3.8L
0.017-0.019 in.
This is what I was able to find:
Cylinder Bore Diameter (Standard) 3.8L
3.7792-3.780 in.
Out of Round (Service Limits)
0.003 in.
Taper (Service Limits)
0.002 in.
Piston Diameter 3.8L-Measured 1.30" From Piston Top
3.778-3.779 in.
Clearance in Bore @ Size Location (New)
-0.0002–0.0015 in
Weight 3.8L
426 ± 5 grams
15.03 ± 0.1764 oz.
Ring Side Clearance
Top Compression Ring 3.8L
0.0012-0.0027 in.
Second Compression Ring 3.8L
0.0016-0.0033 in.
Oil Ring (Steel Ring)
0.0006-0.0089 in.
Side Clearance Wear Limit- Top Ring
0.004 in.
Side Clearance Wear Limit-2nd Ring
0.005 in.
Radial Wall Wear Limit Oil Ring Pack
0.0015 in.
Ring Width-Top Compression Ring 3.8L
0.0462-0.0468 in.
Ring Width-2nd Compression Ring 3.8L
0.0579-0.0587 in.
Ring Width-Oil Ring (Steel Rails) 3.8L
0.017-0.019 in.
Last edited by ronjenx; 01-23-2011 at 06:31 AM.
01-24-2011, 04:52 PM
#5
JK Freak
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So you guys are saying theres nothing that can be done to improve reliability and performance.. An I don't mean exaust and CAI I mean real mechanical gains
Last edited by Jeep Hound; 02-01-2011 at 08:32 PM.
01-24-2011, 06:18 PM
#6
JK Enthusiast
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Maybe we could talk Jeep in to dropping pentastars in our Jeeps after these weak 3.8s blow up at such low mileage. I don't want to get rid of my Jeep but if the this Pentastar is that much better then I would consider trading it.
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01-30-2011, 10:17 PM
#8
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Subscribed. I am also doing a little research myself to prepare in case my oil drinking engine needs work. I already found a speed shop that's willing to do the labor. I'm just looking to upgrade the quality of parts like bearings, rod, rings. Performance gains would be awsome but I'm just want the motor to be reliable if possible. Any info on aftermarket parts would be great. Good luck.
01-31-2011, 02:33 AM
#9
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That's really about it that isn't going to be too intrusive as far as the engine internals go. 0.025" is about as far as I would go, and I understand that at 0.040" you would really be at the fringe of asking for trouble.
As for myself I'm just going to wait out the Pentastar for the 2012s. It isn't going to be a head over heels improvement, but should knock down the operating rpm range by 8-15% with the same power and better torque.
As for myself I'm just going to wait out the Pentastar for the 2012s. It isn't going to be a head over heels improvement, but should knock down the operating rpm range by 8-15% with the same power and better torque.
