hey everyone, I'm visiting from another site, saw the 4 banger board. I've done a lot of searching for upgrades to my 2.5 (hehe, lots of time at work in front of a computer, what else would i do?)
all right, one thing that should be noted before I go on: the 97+ Jeep 2.5l is the same engine as our 2.5l, and the 4.0l l6 is ours plus 2 cylinders on the front, this opens up quite a bit of aftermarket for us.
cams: mopar used to make 3 of em but have discontinued doing so, you can get one from
www.cliffordperformance.com (listed for a jeep) or have one ground from krc performance (321-635-8866, talk to marty)
1.6 roller rockers: mopar makes em, listed for the 4.0l but you can buy them in pairs (exhaust/intake), so just buy 4 pairs instead of 6, this requires lifting the valve cover a bit. yella terra also makes them and they are sold on
www.quadratec.com, just look for them under the 97+ jeep tj section
62mm TB: you can get a ported TB from a 4.0l jeep (same as dak/jeep 2.5l) off of ebay for $180 and it comes with a spacer (it actually does help), or you can search online, i saw somewhere the other day that offered them up to 66mm. make sure it is a tb with the map sensor on the body, some of the jeeps had theirs mounted on the firewall. with this mod you will probably want to grind out a bit of the intake manifold as the manifold will be almost a half inch smaller in diameter, or 1/4 inch on each side
cold air intake: make your own, it's not too hard
exhaust: if you get the tb and intake, you will probably want this too, i haven't been able to find a complete setup, but a decent muffler on pipes from a muffler shop should do the trick
headers: banks, borla, and pacesetter make them for the jeep 2.5. the pacesetters even include a pipe to go from the header to the cat (not sure if it fits our vehicles). there will be extensive modding needed to make the pacesetter work, the banks look like they are pretty much bolt on
valves: mopar makes backcut valves, if you really want to deal with it
port and polish: use the standard abrasives kit and do it yourself, or pay someone else to do it, either way, it will take quite a while b/c of the cast heads. the valve guide bosses stick way out into the middle of everything, so i trimmed mine down. also, the exhaust tubes go from circle to square to circle again, so i opened those up. there isn't so much port matching involved as the ports on the gasket, head, and manifolds are pretty close to the same size
accel 300+: just an upgraded ignition system for us, i don't know how it compares to anyone else's product, haven't seen anyone with the setup yet
jet stage II/venom 400: i have heard that the jet stage 2 works pretty well for our trucks, but you also have to run premium gas and you can't just turn it off, the venom 400 however has an on/off switch and is only active at WOT, but i have not heard any reviews of the product
then there's the ever popular autolite 3923's (one range cooler) and 180 tstat
i haven't seen anyone do it on a dak, but a few jeep owners have rigged up eaton m45's (2-3 liters of displacement) and m62's (2.5-4 liters of displacement) to their 4 bangers, would probably be kind of expensive to do that when you could just go buy a dak with a v8 in it already...also, it is not even close to easy to put any of the other engines into the daks that came with the 4 banger, it might even be cheaper to sell the truck and buy another one with the v8 or v6
that should be about it, but feel free to keep looking for more and better products, i know i do
hope this helps!