258 upgrade - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

 
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post #1 of (permalink) Old 12-25-2002, 11:53 AM
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258 upgrade

Do you think i can really expect a 30-40hp by having double headers and exhaust, with ported and polished head on my 258??? I have 31' with 3:55 (i won't go over 32'), i'd like my jeep to go about 8-9s 0-60mph... I'm not ready yet to change my rear ratio... And i don't want a big V8, nether a 4.0 head swap (a little too expensive)... Someone has a 258 with lot's of modz on it? What can i expect if i put about 1000$ on boosting my 258??? Something significant?!?!

thank's!!!!!
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post #2 of (permalink) Old 12-25-2002, 12:45 PM
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Re: 258 upgrade

Hey bush, You might be wasting your time with the port and polish if you dont change your cam intake or carb, you will see a great increase, porting is an awesome way of increasing the combustion flow, even a small percent gives a big boost, but with a stocker cam yourpower band will only change a little, even though you might get 40hpm I would chage out the cam and lifters,springs and use hardened poushrods, it also depends on how well they port or YOU port your heads, a 4.0 ltr head swap isnt a bad option, even better are 4.0blocks with 232 heads, lots of ways to go huh?? you can try it!!! dont be discouraged if you bend a pushrod or float a valve, their are lots of parts out there, hey heres a tip kragen.com has a holleyII carb for 258's to replace that ol bbd, personally i dont like the bbd, even after modding them, but the holleyII is a great carb....well in my opinion
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post #3 of (permalink) Old 12-25-2002, 12:58 PM
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Re: 258 upgrade

1. Welcome to the forum.
2. Please complete your user profile:
a. It's a nice thing to do.
b. It's helps to know who we're talkin' to.
c It helps to know what's your ride.
d. It helps to know the local in which you live.
3. Read the New Posters Message at the top of the forum.
4. Participate! Two brains are better'n one!
5. For $1000 you can do lots of stuff:
a. Head change, or
b. K&N filter and Cat Back Exaust, or
c. Headers, or
d. Home made EFI.
e. Boneyard engine swap.
6. You'd have to do the labor.
7. You'd have to be responsible enough to start making other changes that'd handle the extra power.
8. Choice is yours... it's your money.
9. Were you I, I'd install a 4.0L head...
10. But then I've already got EFI. [img]images/graemlins/grin.gif[/img]
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post #4 of (permalink) Old 12-26-2002, 09:32 AM
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Re: 258 upgrade

Do you think i'll have similar performance between 4.0 head swap OR polished&ported my 258, with cam, chain roller, headers double and exhaust?

Do i have to change all wires if i go to 4.0 head? Because ALL my wires and brand new!!!! The front of my YJ cut on fire 2 years ago! 5000$US in reparations! That's mostly why i want to modify my engine instead of changing it! Everything is brand new, except the engine itself...

Thank's for all the info!!!
post #5 of (permalink) Old 12-26-2002, 09:54 AM
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Re: 258 upgrade

</font><blockquote><font class="small">In reply to:</font><hr />
And i don't want a big V8, nether a 4.0 head swap (a little too expensive)

[/ QUOTE ]

Well, you just eliminated the two best ideas, swapping it out for a pumped up V8 or doing the 4.0 head and efi. BTW, the 258 is a torquer, it is not a drag race motor. If you really want that kind of performance sell the Jeep and go buy a ricer or something. As you can tell I think this post is pathetic, 0-60 times have no relevance in the wheeling world.
post #6 of (permalink) Old 12-26-2002, 12:55 PM
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Re: 258 upgrade

I hear you cjjeepercreeper! But i'm still thinking of some way to get more power out of my "torquer", that's all i need [img]images/graemlins/smile.gif[/img] Swapping engine or head is too expensive for me... That's why i try to find a way to get 30-40hp out of my 258... Most of the time i'm on the road and i'd like my yj to have a better acceleration... But not as much as a 350... anyway [img]images/graemlins/smile.gif[/img] i appreciate your comment [img]images/graemlins/smile.gif[/img]
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