I've been looking for the right combination for my Jeep. the 4.0L in it is beginning to get very tired and is getting ready to give up the ghost.
I have thoughts of building a 4.7L stroker in the 250 - 300 HP range but I came across these numbers. I would be curious to see if anyone has built one with similar specs.
Also, how much will increasing the compression ratio affect these numbers? (IE. 20cc dish instead of 30cc etc.)
4.6L Low-buck, low CR "rockcrawler"
~ Jeep 4.2L 3.895" stroke crank
~ Jeep 4.2L 5.875" rods
~ Keith-Black Silvolite UEM-2229 +0.030" bore pistons
~ Increase piston dish volume to 30cc
8.8:1 CR
~ Crane #750501 192/204 degree camshaft
~ Ported HO 1.91"/1.50" cylinder head
~ Mill block deck 0.035"
~ Mopar Performance 0.043" head gasket
~ 0.058" quench height
~ 2.25" exhaust
~ Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines, stock injectors with stock 49psi FPR for '96 and later engines
~ 231hp @ 4400rpm, 327lbft @ 2000rpm
I'm more curious of the Torque rating here.... does it truely peak at 2000 RPM?
Cheromaniac wrote:I've updated that recipe since the Crane cam is no longer available:
4.6L Low-buck, low CR "rockcrawler"
Jeep 4.2L 3.895" stroke crank
Jeep 4.2L 5.875" rods
Silvolite UEM-2229 +0.030" bore pistons
Increase piston dish volume to 30cc
8.75:1 CR
CompCams 68-115-4 192/200 degree camshaft
Ported HO 1.91"/1.50" cylinder head
Mill block deck 0.035"
Mopar/Victor 0.043" head gasket
0.058" quench height
Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines, stock injectors with stock 49psi FPR for '96 and later engines
240hp @ 4700rpm, 315lbft @ 3000rpm
My own stroker is a 0.020" overbored version of the "poor man's" stroker with an '01 XJ intake.
two questions then.... if I don't increase the size of the dish in the piston how will affect the performance of this set-up? Are there other considerations to take like cam etc....
Did you find that the stroker made all the difference in the world? worth the work?
Are there any other Jeep Stroker forums that I should be reading as well?
Don't go with the Silvolites if you aren't going to dish them(they have the smallest dishes compared to other over the counter pistons). Less dish=more compression and too much compression=pinging. A Jeep with a stroker is a huge difference, and I've been modding my Jeeps for years, so I can only imagine the amazement from someone with a stockish renix/tired ho stepping up. Jeepstrokers.com and the Strokers yahoo group are the only two places you need to research.
Jak Flash wrote:^ you say too much compression = pinging....
How much compression is too much? I'm thinking of targetting 9.25-9.5 : 1 compression.
at what point do I start considering higher octain fuel? or am I there with these figures?
I know a lot of newbie questions... I just want to do it correctly the first time with no regrets.
I wish I knew what DCR was the limit for 87, 89, and 93 octain. I am running 9.25:1 static comp, 7.75 DCR, zero deck, .043 quench. My compression ratio ended up a bit lower than I wanted. I was shooting for 9.5 SCR/8.0 DCR. When the 1.94/1.50 SBC valves were installed I gained a few more cc's in the head. I also didn't factor in the cc's around the piston on top of the 1st compresson ring. I can run 87 octane with no ping.
no ping and 87 octane is always nice, but there are some "nice" things about a bit more SCR and DCR also... MPG is one of them... another is throttle response.
I am targeting a 10:1 Static compression and 8.3-ish Dynamic compression... hopefully I can get by on 89 with good economy... but I wouldn't be too dissappointed if it ended up on 91. I feel the throttle response is worth it.
lafrad wrote:no ping and 87 octane is always nice, but there are some "nice" things about a bit more SCR and DCR also... MPG is one of them... another is throttle response.
I am targeting a 10:1 Static compression and 8.3-ish Dynamic compression... hopefully I can get by on 89 with good economy... but I wouldn't be too dissappointed if it ended up on 91. I feel the throttle response is worth it.
I agree, but as my daily driver I'm OK with what I got. I put almost 100 miles a day on my Jeep, so it's nice to be able to run 87 octane. I am going to build a .060, long rod stroker with KB 944 pistons from the engine that came out of my 2003 TJ to put in my next project...my version of a Jeep Brute. I am going to build my own bed.
This stroker will have a higher SCR and DCR. I already have the crank, rods, bearings, valve springs, rods and arp rod bolts. I hope Santa brings me the pistons for Christmas.
Jak Flash wrote:Did you find that the stroker made all the difference in the world? worth the work?
Yes to both without a doubt. For mine the difference in torque was most noticeable at low/medium rpm compared to my old modded 4.0 and that's a difference you can really feel in normal daily driving.
I'm running a 4.6 w/9.3ish comp and have to run 93 octane or it will ping. I'm getting 14-15 around town and 17-18 on hwy driving under 70mph in a wrangler w/33's, 4.10's, and a AW4 trans.
YJason wrote:I'm running a 4.6 w/9.3ish comp and have to run 93 octane or it will ping. I'm getting 14-15 around town and 17-18 on hwy driving under 70mph in a wrangler w/33's, 4.10's, and a AW4 trans.
I'm guessing the 9.3:1 is static comp ratio? What is your quench? What cam are you running and is it advanced?
yes, 9.3 SCR, .055 quench, 0 advance on the cam (not 100% sure), comp cam 68-231-4. These are the numbers the machine shop gave me, they put it together not me. I can't run 89 octane or it will ping, I have to make sure I run a good quality 93 fuel.
YJason wrote:yes, 9.3 SCR, .055 quench, 0 advance on the cam (not 100% sure), comp cam 68-231-4. These are the numbers the machine shop gave me, they put it together not me. I can't run 89 octane or it will ping, I have to make sure I run a good quality 93 fuel.
FYI: use a double roller timing chain.
That's strange, I'm running 9.25 SCR, .043 quench 214 @ .050 duration cam advanced 3 degrees, ford cobra xr3e fuel injectors, and I can run 87 octane with no ping...hmmm?
