4.0L HO Jeep Engine Build
OK here was my first impression after a quick 20 block blast around the 'hood:
First fire up was late Sunday afternoon after some trial and tribulation. I took it for a little 20 block blast tonight and the throttle response is incredible. I can't wait to go for a hwy cruise but I wanted a shakedown run tonight to make sure everything was honky dory. Squealing the tires around corners was easy stuff. I'm not going to beat it up just yet though.. :-D It about jerks my head off right off idle and I had to quickly learn to be very, very easy on the throttle when taking off from a stop.
The first few blasts are just touching the throttle and the 4k blast was just half throttle if that.
YouTube- SSBuildDynomax.AVI
For those that haven't seen the build thread, I built this engine in a super stock format using the best of the best of all the years that this engine was in production plus some custom machining and a few "non-stock" parts. My goal was a sensible, long-lasting daily driver with added power but a somewhat stock cam.
I'm very anxious to see what this will do at higher rpms as well. Will it pull past 4k? Will power continue to build to redline? What will the mpg be? How well will it pull a 700-800 lb. trailer? What would I do differently next time? About the only thing I know for sure is that is
pulls hard right off idle and would smoke my new chevy work van vortec v-6 off the line. It really slingshots from light to light with minimal throttle input.
I now have just about a 100 miles on it and here are my latest impressions:
The computer seems to have had time to adjust and it fires up easy when cold and settles right down to a 750 rpm idle. There used to be a lean spot at about 2000-2200 rpm that has dissapeared and the exhaust seems to have even quieted down a bit too. The alignment guy had even mentioned how smooth it idles. I had to do ball joints so it's going back to him this Sat.
The throttle is not so touchy anymore but it still takes care not to ram the slow poke in front when coming off a red light. :-D Cruising around town and accelerating to 30-45 mph takes no more than 1/8-1/4 throttle if that. Any more and I'll get a ticket. What's really interesting is when I drop the trans into 1-2 and mash the throttle on an on ramp. It pulled cleanly and shifted into 2nd at 5k then buried the 85mph speedo by 5200 rpm and was still pulling balls to the wall. It was eerie. I had to to hit the brakes hard before merging. Don't forget that this at well over 5200' altitude. I truly didn't expect that kind of high rpm performance given the cam I used and how torquey it feels around town.
I used the stock intake as I feel that Chrysler did an excellent job on the design. I did use a K&N flat filter and I'll be straight up with you all, I feel that K&N's make great "Rock Blockers" but I'd be concerned in truely dusty off road conditions. I may add an aftermarket intake tube and cone style filter so I can simply tie on a pre-filter if going off road but I doubt I'd see much of a performance gain. I may be taking this to a chassis dyno in August and that will tell the real story. I did have an intake whistle that I was able stop by simply tightening up the clamp on the throttle body to air intake. This thing really sucks, lol.
With 15W-40 and the Hughes break in cam additive I'm running 40 psi at idle hot after a 1 hr. hard drive and 60 or so on the hwy. After all the air was bled out of the cooling system and using the A/C it never runs above 185. No leaks and no drips. It hasn't used any noticeable amount of oil whatsoever. mpg remains to be calculated.
After all is said and done and with the engine about broken in and the computer working seemingly as it should, I think that a 20 hp increase is a very, very conservative estimate. MeMike may well be right as the high rpm (above 4k) performance really took me by suprise. I had driven a 2006 BMW X3 with a straight 6 up here in the rare air and this is suprisingly comparable in the power department. The throttle response is better on the Jeep (thank the fly by wire on the BMW) and the trans on the BMW is way better (mine has some serious mileage on it. I need to get it to Andrews Transmissions in the future). Although it wouldn't beat the BMW on the highway (or around curves, lol) it would certainly suprise them to hang on the on ramp with them till about 85-90. :)
In summation, these are the mods I made:
1. 99+ block with the main cap girdle.
2. Crank and rods set to .002-.0025 clearance.
3. MP HV oil pump.
4. Blocked decked a total of .037" for zero piston to head clearance. Total measured CR is 9.325
5. Speed Pro late model pistons with the coated skirts and thinner metric ring pack.
6. Piston pin bores set to .0007" clearance.
7. Ring gap at factory specs.
8. '92 heads home ported and milled by DC to .007" to give a cc volume of 58.
9. Heads had the valve job done by DC Racing who moved the intake seat out to the outer 1/3 of the valve seat and installed new bronze valve guide liners.
10. I shimmed the late model (99+) valve springs to '92 specs.
11. Stock Rockers with the addition of .030 Hesco pedestal shims to set the lifters at .035" pre-load + or minus .005".
12. Stock late model pushrods.
13. Fel pro .050 Head Gasket compressed.
14. Deep gasket match on both the head and intake.
15. Late model large plenum intake manifold.
16. Stock injectors. 19 lb Mustang 4 hole injectors I'm saving for dyno tuning.
17. BBK 62mm throttle body.
18. Stock airbox with K&N filter.
19. Cheap ARP stainless header.
20. Magnaflow hi-flow cat. Not so cheap, lol.
21. Dynomax cat back exhaust.
22. NAPA manifold to cat pipe. The original has a rediculously restrictive crimp in it. The NAPA part is much better but still not ideal.
23. Cloyes timing chain.
24. The weird cam with 4.2 specs but 4.0 HO lift installed at 110 degrees.
25. Hesco head bolts.
I think that's pretty much it, but if I think of something I forgot I'l be sure to add it in.
What would I have done differently?
I would've used the Lunati cam I mentioned earlier. :read2: it would have required different springs, spring seat machining, different retainers, valves and locks.
In conclusion,
All in all I'm very, very happy with this build and it seems to have met or even exceeded my goals and I see no problem with passing emissions. I can run this thing in my garage for 5 minutes without my eyes watering (don't do this at home kids....) Most of the mods are internal and the external ones all have CARB exemptions..... pretty much, lol. Like any engine recipe, I can't guarauntee the same results unless this build is follwed to the "T". Keep in mind that every block and head was cast on a different day too. Tolerance stacking is a *****. :read2:
