XJ: Easy upgrades to get more HP outta your 4.0 - Great Lakes 4x4. The largest offroad forum in the Midwest

Ford forever · August 9th, 2012, 09:54 AM

Looking for some easy upgrades to get a few extra ponies from my girls jeep. Got a nice cold air, did a full tune up(dist,plugs,wires,all fluids) looking at bigger injectors kinda wondering what cc would work? besides stock. Ordered a bigger header from flowmaster an 3" all the way back, no cat. Not lookin to do any major motor work it's her dd,for now lol

I'm open to Any suggestions.

JohnL · August 9th, 2012, 09:56 AM

Best HP per dollar is usually spraying it.

92FleXj · August 9th, 2012, 10:01 AM

Quote:

Originally Posted by JohnL

Best HP per dollar is usually spraying it.

Lol

SlayerXJ · August 9th, 2012, 10:34 AM

I would not go bigger than 2.5 and keep a cat. get a high flow. with that setup you're gonna lose torque.

ajmorell · August 9th, 2012, 10:39 AM

3" is too big on the 4.0 unless you're making really high hp. 2.5" is ideal. 99+ intake manifold will net some gains. Where the 4.0 really struggles is with air flow, so some head work will make a nice difference.

Ford forever · August 9th, 2012, 12:19 PM

Thank for the advice on the exhaust, I thought it was a little big myself, glad we only ordered the header. As far as head work I figured when we decide to pull it apart were defiantly going 4.6 stroker. It's not that expensive an like I said it's her dd a v8 is unpractical for her lol

What about a throttle body or spacer? worth the trouble or na ?

SlayerXJ · August 9th, 2012, 01:57 PM

I noticed a slight difference, most people talk shit about them, but most have never bolted one on either.
Just don't get the one that whistles!

ajmorell · August 9th, 2012, 05:26 PM

Snake Oil. If you understand how it's supposed to work you'll understand why. I ran one for a little while before retiring it to a paper weight. Your best bet for gains are:

-99+ Intake
-Header of some sort + 2.5" mandrel bent exhaust (do what you want with the cat/muffler, I run a high flow cat and no muffler)
-Cam (compounding this with the above mods)

92FleXj · August 9th, 2012, 06:46 PM

Quote:

Originally Posted by SlayerXJ

I noticed a slight difference, most people talk shit about them, but most have never bolted one on either.
Just don't get the one that whistles!

I have the whistler.... Gets annoying real quick...

SlayerXJ · August 11th, 2012, 08:22 AM

Quote:

Originally Posted by BennettisTileCo

I have the whistler.... Gets annoying real quick...

I bought mine used from Hancho for like 30 shipped, so it wasn't a huge investment.

But holy shit, if i knew it whistled, i would have passed.

Every passenger is all WTF is that whistle?

I swear when i first installed it the throttle response felt snappier.

Why YJ? · August 11th, 2012, 09:08 AM

Read up:

http://www.jpmagazine.com/techarticl...ing_true_lies/

Ford forever · August 14th, 2012, 10:19 AM

Its a 99 Cherokee so it already has the 99+ intake. I Might have a little head work done idk well decide over the next few months.

Rob the plumber · August 14th, 2012, 10:30 AM

Head work and a better cam can pick up good power on a 4.0l.
Porting your throttle body helps a little and its free. You can also modify your crankshaft position sensor to gain a little timing too.

Ford forever · August 14th, 2012, 10:32 AM

Quote:

Originally Posted by Why YJ?

Read up:

http://www.jpmagazine.com/techarticl...ing_true_lies/

Read the whole article an all I got was to get any good power gain from bolt on products you first need head, an valve work. Exactly what I figured. Unless the head will allow more flow the ad ons are just a waste of time unless you want better mildly better gas mileage.

Ford forever · August 14th, 2012, 10:40 AM

Rob- prolly what well end up doing. My new question is how much head work, an what cam will give me that little extra hp I'm looking for? I have been looking an have a few narrowed Down but I'm still taking opinions on what I should end up running.

Rob the plumber · August 14th, 2012, 11:17 AM

port match, and cleaning the bowls up is all I'd do. You could have the head machined for larger valves but you will still pick up good power with the basics. I'd also stay mild on the cam. Les chance of wiping a lobe out and better driveability. Replace the springs too while the head is apart. I've also read that the 91-95 head flows the best, so maybe look into that.

ajmorell · August 14th, 2012, 12:52 PM

When I had my 4.0 rebuilt I had a 3 angle job done on the valves and the head port matched. Gasket/port match the exhaust manifold and intake as well. The intake is easy since it's aluminum, on the exhaust/header I just smoothed up the runners since all I had at my disposal the time was a dremel. As for cams, I'm running Comp Cams 68-232-4 and I'm happy with it.

Mr.Green again · August 14th, 2012, 02:03 PM

Quote:

Originally Posted by Rob the plumber

You can also modify your crankshaft position sensor to gain a little timing too.

Or you can just bust the distributor clocking location bracket and rotate the distributor. I found this out on accident.

August 9th, 2012, 09:54 AM	#1
Ford forever Bought another jeep Join Date: 01-28-09 Location: North Muskegon, michigan Posts: 533 iTrader: (0)	Easy upgrades to get more HP outta your 4.0 Looking for some easy upgrades to get a few extra ponies from my girls jeep. Got a nice cold air, did a full tune up(dist,plugs,wires,all fluids) looking at bigger injectors kinda wondering what cc would work? besides stock. Ordered a bigger header from flowmaster an 3" all the way back, no cat. Not lookin to do any major motor work it's her dd,for now lol I'm open to Any suggestions.

August 11th, 2012, 09:08 AM	#11
Why YJ? Don't be a wuss... HIT IT Join Date: 12-12-08 Location: West Branch,MI Posts: 1,123 iTrader: (6)	Read up: http://www.jpmagazine.com/techarticl...ing_true_lies/ __________________ Run of the mill YJ with Dana 60's and Irok's..SOLD 97 XJ Family Trail Rig Paul www.teamhodges.com

August 9th, 2012, 09:56 AM	#2
JohnL Go until it breaks. Join Date: 02-20-09 Location: Greenwood , Indiana Posts: 2,101 iTrader: (8)	Best HP per dollar is usually spraying it.

August 9th, 2012, 10:34 AM	#4
SlayerXJ To Live is To Die Join Date: 04-22-06 Location: Ann Arbor, MI Posts: 2,814 iTrader: (91)	I would not go bigger than 2.5 and keep a cat. get a high flow. with that setup you're gonna lose torque.

August 9th, 2012, 10:39 AM	#5
ajmorell Senior Member Join Date: 01-22-07 Location: Santa Fe, NM Posts: 3,022 iTrader: (16)	3" is too big on the 4.0 unless you're making really high hp. 2.5" is ideal. 99+ intake manifold will net some gains. Where the 4.0 really struggles is with air flow, so some head work will make a nice difference.

August 9th, 2012, 12:19 PM	#6
Ford forever Bought another jeep Join Date: 01-28-09 Location: North Muskegon, michigan Posts: 533 iTrader: (0)	Thank for the advice on the exhaust, I thought it was a little big myself, glad we only ordered the header. As far as head work I figured when we decide to pull it apart were defiantly going 4.6 stroker. It's not that expensive an like I said it's her dd a v8 is unpractical for her lol What about a throttle body or spacer? worth the trouble or na ?

August 9th, 2012, 01:57 PM	#7
SlayerXJ To Live is To Die Join Date: 04-22-06 Location: Ann Arbor, MI Posts: 2,814 iTrader: (91)	I noticed a slight difference, most people talk shit about them, but most have never bolted one on either. Just don't get the one that whistles!

August 9th, 2012, 05:26 PM	#8
ajmorell Senior Member Join Date: 01-22-07 Location: Santa Fe, NM Posts: 3,022 iTrader: (16)	Snake Oil. If you understand how it's supposed to work you'll understand why. I ran one for a little while before retiring it to a paper weight. Your best bet for gains are: -99+ Intake -Header of some sort + 2.5" mandrel bent exhaust (do what you want with the cat/muffler, I run a high flow cat and no muffler) -Cam (compounding this with the above mods)

August 14th, 2012, 10:19 AM	#12
Ford forever Bought another jeep Join Date: 01-28-09 Location: North Muskegon, michigan Posts: 533 iTrader: (0)	Its a 99 Cherokee so it already has the 99+ intake. I Might have a little head work done idk well decide over the next few months.

August 14th, 2012, 10:30 AM	#13
Rob the plumber Licensed master plumber Join Date: 06-14-06 Location: New Baltimore, Michigan Posts: 4,584 iTrader: (27)	Head work and a better cam can pick up good power on a 4.0l. Porting your throttle body helps a little and its free. You can also modify your crankshaft position sensor to gain a little timing too.

August 14th, 2012, 10:40 AM	#15
Ford forever Bought another jeep Join Date: 01-28-09 Location: North Muskegon, michigan Posts: 533 iTrader: (0)	Rob- prolly what well end up doing. My new question is how much head work, an what cam will give me that little extra hp I'm looking for? I have been looking an have a few narrowed Down but I'm still taking opinions on what I should end up running.

August 14th, 2012, 11:17 AM	#16
Rob the plumber Licensed master plumber Join Date: 06-14-06 Location: New Baltimore, Michigan Posts: 4,584 iTrader: (27)	port match, and cleaning the bowls up is all I'd do. You could have the head machined for larger valves but you will still pick up good power with the basics. I'd also stay mild on the cam. Les chance of wiping a lobe out and better driveability. Replace the springs too while the head is apart. I've also read that the 91-95 head flows the best, so maybe look into that.

August 14th, 2012, 12:52 PM	#17
ajmorell Senior Member Join Date: 01-22-07 Location: Santa Fe, NM Posts: 3,022 iTrader: (16)	When I had my 4.0 rebuilt I had a 3 angle job done on the valves and the head port matched. Gasket/port match the exhaust manifold and intake as well. The intake is easy since it's aluminum, on the exhaust/header I just smoothed up the runners since all I had at my disposal the time was a dremel. As for cams, I'm running Comp Cams 68-232-4 and I'm happy with it.