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Common 4.0. Performance Questions...

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Old 12-15-2009, 07:14 PM
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Default Common 4.0. Performance Questions...

just got this 94 cherokee 5 speed and fixed a bunch of stuff and here soon ima do something with the exhaust and intake...i gotta cone filter already so im gonna most likely run a pipe from the tb to the bottom half of airbox and have the filter sit there, and i cant decide whether or not to run it without a muffler, ive heard a few no muffler jeeps on u tube and they sound awesome, they got that unique inline sound...do they run good like this or would it benefit performance wise more with a muffler like a flowmaster or something? also the header is cracked(ofcourse) im gonna weld for now but anyone know a good place to order a one thats not to expensive and is known to be good? i saw a few on ebay for under 200 but might be a little iffy idno i think there 1-5/8, lastly! can my 94 cherokee be chipped? like a superchips flashpaq or something or is that the 97 up or whatever? thanks
Old 12-15-2009, 07:55 PM
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I saw those headers on ebay, they seem like they are good quality, being it is stainless and has 1/2 thick flanges...
Old 12-16-2009, 03:41 AM
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So I see your avatar and think to my self if that was a real Jeep there would have to be a step ladder in there to make that work, well at least with my Jeep
Old 12-16-2009, 04:04 AM
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I don't know much about the performance end of your questions, but I just wanted to say that I'd steer clear of ebay parts. You never know what you are getting when it comes to sites like ebay or craigslist. Try googling what you want and find a good parts store online before going to ebay. Even tho sites like ebay tend to have methods you can settle disputes over a sale, you're still not guaranteed satisfaction. If you go thru an online store, however, chances are BETTER [not necessarily guaranteed, but better] that you'll get what you want/need from them, because the store is trying to make a name for itself.

Just my $.02
Old 12-16-2009, 04:08 AM
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Get a Borla Header, not cheap but arguably one of or the best header made for the Jeep 4.0 when you do that, swap on an 00 or newer intake manifold(the rounded style) at the same time. Other than camming or a supercharger/turbo there's not much more you can do to beef up the stock 4.0 without stroking it. Just get a good filter, help it breath clean cold air and it'll have plenty of power for up to 36s with proper gearing
Old 12-21-2009, 01:12 PM
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alright cool, as for the exhaust would running no muffler hurt performance or would it gain a lil bit? i like the sound of the 6 inlines with no muffler but if its gonna take a lil bite out of hp then ill just use a flowmaster muffler or something, and if anyone has experience with any ebay headers or know of another good one just let me know, borla is very nice but the header is like 600 some bucks which isnt far from what i paid for the jeep lmao, thanks
Old 12-21-2009, 01:35 PM
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Here's a picture of a test they did on JP Magazine on the back yard mechanic air intake. And what they said about it... I believe the mileage dropping off was due to another problem they had though.

JP Magazine Quote about intake inm picture:
"The first thing we tried was a low-buck redneck-style homemade air intake. Our seat of the pants dyno said we'd made power, but the real dyno disproved it. We also didn't see any change in mileage out on the highway; in fact we started seeing the mileage drop off."
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Old 12-21-2009, 01:43 PM
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straight pipes (no muffler ) is a bad idea on any engine that is naturally aspirated because you loose back pressure and you can burn your exhaust valves and even crack them when the exhaust sucks in a little cold air. EGT's are usually around 1800* farenheit, now think of 70* or 80* air getting sucked up the exhaust and touching that 1800* exhaust valve...Now, does this happen often? no. Is it possible? yes it has happened before. Just get a muffler that sounds good, its your best bet to keep your 4.0 alive for a long time.
Old 12-21-2009, 02:33 PM
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im going with everything borla for my 4.0 the sounds is amazing.
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