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Unread 09-03-2013, 01:51 PM   #1
iLuvJeepYJ
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89 yj not really getting past 70mph

Alright I have an 89 yj with mc2100 carb all dialed in, timing is right, straight piped, new engine and tranny, 4" lift on 33x12.50 tires, I'm getting tired of driving in the slow lane and bogging down on hills. Please help!

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Unread 09-03-2013, 02:02 PM   #2
booboowv77
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In my opinion 70 on 33's is fast enough, but if you want to stop the bogging down go to 4.10 gears in the axle, and for a little more speed up grade your distributor with either Team rush, or HEI should help. I get 70 out of mine with no problems and I am on 35's but for me it just don't seem save to go any higher. It's a jeep not a race car!
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Unread 09-03-2013, 02:10 PM   #3
warthog312
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My YJ when it still had the 4cyl and 33's would just hit a wall at like 65mph and just would not go any faster. You have to remember these things have the aerodynamics of a waffle house and then we take and make it worse by adding lifts and tires, and they are usually old and tire engines as well. I really don't think they were all that apt at highway driving when they were brand new.
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Unread 09-03-2013, 02:27 PM   #4
rambo3489
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What gears are in the axle? And I agree 70 is plenty fast. I don't see much over 60-65 in mine on 35s with 4.88 and a similar setup as you. I could push it to MAYBE 75-80 on the flats but choose not to. This all goes out the window on any incline. It stands no chance climbing at speed. You have to live with it.

If you want the left lane you should have gotten a charger. Or a V8

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Unread 09-06-2013, 09:26 AM   #5
iLuvJeepYJ
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Stock gears, think I'm gonna do the TFI upgrade and see what happens
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Unread 09-06-2013, 09:44 AM   #6
Que89YJ
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Just remember you cant make a silk purse from a sows ear. The 2.5 is a good motor for what it is. It been over discussed on the forum. You can eek out a little more hp by finding and swapping in a MPFI 2.5L fuel injection, going to an electric fan, and regearing. I am saying just be realistic with what you have. I have my 2.5 and I cant drive it like my Charger RT but when it comes to fun the Charger is a distant second lace to the fun I have in my Jeep.
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Unread 09-06-2013, 09:55 AM   #7
iLuvJeepYJ
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Quote:
Originally Posted by Que89YJ
Just remember yo cant make a silk purse from a sows ear. The 2.5 is a good motor for what it is. It been over discussed on the forum. You can eek out a little more hp by finding and swapping in a MPFI 2.5L fuel injection, going to an electric fan, and regearing. I am saying just be realistic with what you have. I have my 2.5 and I cant drive it like my Charger RT but when it comes to fun the Charger is a distant second lace to the fun I have in my Jeep.
I have the 4.2L
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Unread 09-06-2013, 10:11 AM   #8
Old4X
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Stock gears are 307s. If you want more speed, regear or install nitrous. You won't do anything with TFI except spend money for no reason
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Unread 09-06-2013, 11:02 AM   #9
dancytron
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Doesn't TFI mean the same thing as Team Rush upgrade with a different coil too?
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Unread 09-06-2013, 11:05 AM   #10
zeus87gn
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Regear - 3.73s are perfect for 33s and the 4.2 - 4.10s are a tad short, but I have the 5 speed
The ignition upgrade will help the engine run better but will not give you the results you are looking for

Also, do you have your dist corrected for the bypass and carb you are now running?
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Unread 09-06-2013, 11:11 AM   #11
Old4X
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Quote:
Originally Posted by dancytron View Post
Doesn't TFI mean the same thing as Team Rush upgrade with a different coil too?
Yes
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Unread 09-06-2013, 11:55 AM   #12
SamzJeep
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I have an '88, 4.2, Team Rush, MC2100, 8.8/Dana 30 with 4.10's, AX15 on 35's and I average 60-65 on the freeway. I can go a bit faster on a good day (no up hills/wind), but I keep her at 60 mph. It would be nice to be able to go faster when you wanted to, but like everyone else is saying..."it's a Jeep". I'm sure you can get them going faster without killing it, but I would assume that would include having a V8 and the right gears and a lot of cash. I'm happy with my rig. She gets me everywhere I want to go...just maybe not as fast as others can go! Keep the top off, crank up the tunes and enjoy the ride!
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Unread 09-06-2013, 04:13 PM   #13
zeus87gn
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I can hit 70 with power to spare - Its at that speed I start to get nervous - 65 is fast enough in my rig
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Unread 09-06-2013, 06:27 PM   #14
bigbossd1030
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Quote:
Originally Posted by zeus87gn
I can hit 70 with power to spare - Its at that speed I start to get nervous - 65 is fast enough in my rig
Yeah,
I can hit 160km and that's way too scary. Thing feels like it's gonna loose the wheels as soon as I stop lol.
But this is with 30" stock everything. I won't go that fast again. 120km ish is fast enough.

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Unread 09-06-2013, 07:33 PM   #15
iLuvJeepYJ
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Quote:
Originally Posted by zeus87gn
Regear - 3.73s are perfect for 33s and the 4.2 - 4.10s are a tad short, but I have the 5 speed
The ignition upgrade will help the engine run better but will not give you the results you are looking for

Also, do you have your dist corrected for the bypass and carb you are now running?
What do you mean bypass?
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