RUNNING stroker specs and pinging survey DCR/SCR

[ccpanel]

i've spent the last 4 days glued to my computer reading every post I can get my hands on to find out what build is going to be best for me.
i've read dino's site 10,000 times and understand his builds.
however... what I can not find is anyone definitively talking about pinging so here goes.
can you please itemize your build?
I want info ONLY on engines that have been DRIVING with your butt in the seat.
no "bench racing" here.

so please do your best to limit dialogue-just state your specs and help me and hopefully others to nail down the best real world build.

how much does your rig weigh or what is it? lifted?
tire diameter
axle ratio
transmission(auto/stick?) model
year of block/part number if known
year/part of crank
year/part of rods
camshaft part number and specs if known
actual part number and oversize of piston and if any non-stock dishing
headgasket thickness/part number
year of head/part number if known
any port/polish?
oversize valves?
year/style of intake
year/style of exhaust manifold
carb or FI

SCR(static compression ratio)
DCR(dynamic compression ratio)

what octane gas?
what elevation do you drive/live?

DOES IT PING? and when?

[eliv1]

1988 Israeli CJ8, weighs about 4000lbs, lifted 4.5", 4.10 gears on 33" tires, T176 tranny for now (just finished rebuilding an AX15 that will go in there).

Engine: 258 block overboard 0.125", stock 4.0L pistons, with a 4 counterweights crank totaling a 4.5L displacement. 4.2L rods, dont know the part number but it should be 80-86 rod and crank.
I run a compcam 68-231-4 cam with a home P&P, standard valves and a Borla Header 2.5" piping and a flowmaster delta40.

It used to run on a MC2100 carb, a 91-95 intake MPI and now a 99+ intake, never had any ping at all.
the fuel is 95 RON Rated octane.

[Cheromaniac]

Dino chiming in here.
My original stroker build was a modified version of the 4.6L low-buck stroker option 1 but with +0.020" 677P pistons (CR 9.25:1) and a Crane 753905 cam. The engine didn't ping on 91 octane but I never ran anything lower.
When the Crane cam/lifters failed after 34k miles, I swapped my old stock cam back in so it became a 4.6L version of the "poor man's" simple stroker instead. This lowered the DCR by 0.4:1 so now I can run 89 octane.
Last week I had my old intake manifold swapped out for an '01 XJ version. I haven't driven the Jeep much since then to judge if it's made any difference to performance and fuel economy.

[Bodo]

Dino, the 9.25:1 CR that you mention...Is that SCR or DCR?

[jsawduste]

how much does your rig weigh or what is it? lifted? YJ with a bunch of added stuff SOA + 1"BL 4500/5000
tire diameter 37`s
axle ratio 5.13
transmission(auto/stick?) model NV4500/Atlas
year of block/part number if known 93
year/part of crank 12 wt
year/part of rods Eagle
camshaft part number and specs if known Hesco 274/480
actual part number and oversize of piston and if any non-stock dishing Diamond custom .080 over
headgasket thickness/part number Fel Pro .043
year of head/part number if known 93 HO
any port/polish? Yep
oversize valves? Nope
year/style of intake 2000 New Style
year/style of exhaust manifold Edlebrock
carb or FI 64mm FI

SCR(static compression ratio) 9.56
DCR(dynamic compression ratio) :huh:

what octane gas? 93
what elevation do you drive/live? 500ft

DOES IT PING? and when? Nope/never

HTH

[Cheromaniac]

Dino, the 9.25:1 CR that you mention...Is that SCR or DCR?

Here are my stroker specs in detail:

Specs are as follows:

Jeep 4.2L 3.895" stroke crank
Jeep 4.2L 5.875" rods
Sealed Power 677P +0.020" pistons
Displacement 4563cc
SCR 9.25:1, DCR 8.03:1 using Silvolite KB calculator
Stock '92 HO 4.0 camshaft
Ported '92 HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket
0.088" quench height
Ford Racing 24lb/hr injectors with stock 39psi FPR
Homebrew CAI
Modified Mustang 65mm TB with tapered 65mm to 62mm TB spacer
'01 XJ intake manifold (swapped in last week)
Modified Borla header with 3" outlet and custom 3" headpipe
Magnaflow center muffler, Flowmaster rear muffler (no cats), Mike Leach 2.5" tailpipe with Pacesetter Monza 3" chrome tip
Flowkooler water pump
JET 180* t'stat
Dual electric fans
Custom 3-row radiator

My Jeep has 227/70R15 tires, stock 3.07 gears, and an AX-15 5-speed. Engine will run on a blend of 87 and 91 octane without pinging in summer. Haven't tried 87 octane alone in winter though.
Dyno'd 200rwhp/254rwtq last year before I did the '01 XJ intake manifold swap.

[Comanche91]

Hey Dino - glad you got the manifold installed. Looking forward to see your assessment mate.

[Cheromaniac]

I'll hopefully have something to report soon and maybe a dyno test later on.

[1bolt]

I understand the call to limit dialog but IMO your approach is backwards We don't need a survey to understand what causes strokers to Ping or not. The fundamentals of engine building apply here. High compression + poor quench = higher octane requirements. It really is that simple!

It can get more complicated but it starts there... (The combustion chamber shape becomes very important once you get quench spec as tight as possible...)

If you want a stroker that has optimal low/mid torque with an "RV cam" (low overlap cam) and you don't want it to ping, you should make the higher initial cost investment of custom pistons (Including so called stroker pistons by KB etc.) So you can get good quench; Then high compression is your friend.... Within the confines of pump gas, high compression will make more of that low torque you're after. The low overlap will make more cylinder pressure which = more torque, due to higher dynamic compression. Contrary to the previaling assumptions in Jeep stroker land, Compression is not the enemy, it's part of why the stroker can make so much more torque than a stock 4.0.

The "budget" build costs less in the short term... but unless you go with a high overlap street/strip cam it will cost more in the long run. The high overlap cam favors horse power over low and mid range torque and so is not optimal for what most Jeep engines are being built for.

If you're building a street/strip jeep (not too many people doing that), and it needs to be cheap, and it's not important that you get optimal power off idle to 3500 RPM's then the budget build is great. However If you're building a purpose built JEEP with the major emphasis on TORQUE for pulling, off roading, rock crawling, towing etc. then the budget build is a poor choice unless you simply don't have the cash to spend more right then and there.

We're Jeepers and many of us probably don't have that extra cash (I know I don't and I didn't back when I built mine). So it's understandable that the budget builds are the mainstay. However there are people here building competition rigs, or who have the cash to "do it right"... So this information should be made clear.

Even if you're doing a street build, using a high overlap cam to "bleed" dynamic compression off to make up for poor quench and low octane fuel, is a poor build choice. But if it's what you can afford, it'll have to do... Just realize that somewhere down the line you might be springing for aftermarket parts to try and combat a bad case of pinging due to poor quench and high compression... A set of $500 pistons and a couple cuts off the block is cheap compared to an aftermarket fuel and spark computer, and forget about the dyno time to tune it... The dyno time itself could cost more than difference between a custom piston stroker and a budget build.

Anyway my specs: 4.6 simple stroker (poor quench) somewhere around 9.5:1 CR with a low overlap (High torque or RV) Clifford cam pings in hot weather on 87 or 89 octane, 93 works good and is required on hot summer days. It's Lifted (3.5") 33/12.5 inch BFG's 4.56 gears, Detroit trutrac's front and rear. AW4... A True cool air intake (sealed to cowl hood opening) helped reduce ping on lower octanes in hot weather but I still run 93 in the middle of summer. I personally have spent nearly as much money battling ping as the cost of custom pistons and a couple extra cuts on the block would have cost me. And I DON'T have an aftermarket engine managment system installed (currently).

[ccpanel]

I understand the call to limit dialog but IMO your approach is backwards We don't need a survey to understand what causes strokers to Ping or not. The fundamentals of engine building apply here. High compression + poor quench = higher octane requirements. It really is that simple!
SNIP
Anyway my specs: 4.6 simple stroker (poor quench) somewhere around 9.5:1 CR with a low overlap (High torque or RV) Clifford cam pings in hot weather on 87 or 89 octane, 93 works good and is required on hot summer days. It's Lifted (3.5") 33/12.5 inch BFG's 4.56 gears, Detroit trutrac's front and rear. AW4... A True cool air intake (sealed to cowl hood opening) helped reduce ping on lower octanes in hot weather but I still run 93 in the middle of summer. I personally have spent nearly as much money battling ping as the cost of custom pistons and a couple extra cuts on the block would have cost me. And I DON'T have an aftermarket engine managment system installed (currently).

broke as all get out , MUST have a motor to put in my truck. we out in la-la land dont get 93 octane. best we can buy on the street corner is 91 and a weak 91 at that.
broke as heck.
motor going into a rig that will see 99% street miles, 50% of that towing car trailer. 50% of that empty.
total annual miles under 5k.
my rig;
http://3.bp.blogspot.com/_Ok8GzUd9n14/S ... C_9208.JPG
theres a 1981 waggy chassis buried under there.
mark

[ccpanel]

i've spent the last 4 days glued to my computer reading every post I can get my hands on to find out what build is going to be best for me.
i've read dino's site 10,000 times and understand his builds.
however... what I can not find is anyone definitively talking about pinging so here goes.
can you please itemize your build?
I want info ONLY on engines that have been DRIVING with your butt in the seat.
no "bench racing" here.

so please do your best to limit dialogue-just state your specs and help me and hopefully others to nail down the best real world build.

how much does your rig weigh or what is it? lifted?
tire diameter
axle ratio
transmission(auto/stick?) model
year of block/part number if known
year/part of crank
year/part of rods
camshaft part number and specs if known
actual part number and oversize of piston and if any non-stock dishing
headgasket thickness/part number
year of head/part number if known
any port/polish?
oversize valves?
year/style of intake
year/style of exhaust manifold
carb or FI

SCR(static compression ratio)
DCR(dynamic compression ratio)

what octane gas?
what elevation do you drive/live?

DOES IT PING? and when?

btt

[Brian E]

My wifes stock 4.0 93 Grand Cherokee will not run on anything under 93 summer or winter low altitude Florida. That dang thing pings at the slightest throttle even on 89. It has done that since day one new. My 98 wrangler Titan junk motor pinged the first few times they rebuilt it this time it did not. I even checked the rod bearing uppers this rebuild. The head was a stock 0331 bit sure of the cc but should be 57, the head gasket was .051, the deck height is anywhere between .030 and .025. The pistons are Hypertutectic so they should be 11.5cc. The cam is a mystery becasue they did not put what I ordered in there the last time but the lift at the rocker is .448 and I calculated the cam while it was out and it came too .449 so i was pretty on but have no idea of duration. I hope this time it does not ping either. 57 cc head shaved .010 .040 head gasket, .027 deck 11.5cc Hypertutectic, 254 duration cam at 4 deg adv and .477 int .493 exh. comp Static about 10.17 Dynamic 8.87 if I remeber the calculations. I can mess with timing and fuel curve later.I also am looking at faking out the oxgen sensor readings. And added a good header with duel head pipes into 2.25 pipe.

[apwatson50]

Stock 1997 cherokee auto,

Engine
4.6L
10.25 SCR
block decked to give ~.060 quench with felpro gasket.
SP 15.5cc +.040 pistons
specs from memory don't have build sheet in front of me. hence the ~
crane cam
99+ intake
ebay header 2.5" exhaust high flow cat
7120 head, mild port/polish.
28lb ls1 injectors, no other tuning.

Here at 5500ft elevation will run on mid grade 87 octane in summer with slight ping, during winter no ping. So during the summer it runs on 91 octane no ping.

[dwg86]

I know this thread is old, but since my stroker is in and running...

2003 TJ, 5 speed
2000 block bored .040, zero deck
Mopar performance .043 head gasket
Fel Pro head bolts
Clevite hypereutectic pistons(silvolite reboxed) dished to 21cc(thanks oletshot)
258 rods, beams polished and shot peened, ARP rod bolts, big end resized
258 12 weight crank .010 mains, standard rods
clevite main bearings, federal mogul rod bearings
7120 head, DIY polish, combustion chamber opened up to 62.4 cc's, hardened exhaust seats installed
SBC 1.94/1.50 stainless undercut swirl polished valves
Mopar performance valve springs, comp cams retainers and 10 degree locks
Crower 1.6 rocker arms, comp guide plates, Trend one piece, chrome moly pushrods(9.350)
HV oil pump
Engle cam (214 duration @ .050 / .501 lift / 112 lobe centers / 3 degree advance ground into cam
Stanadyne lifters(Made in USA)
JP Performance double roller timing chain
Spring and pin removed from cam/solid pin made to retain cam
extra oil line to cam sensor drive gear
2000 intake
24# injectors(or 27#...same ones they sell at Five-o)
Stainless Rugged Ridge header for 2003 wrangler
LUK gold series clutch
Rotating assembly balanced
9.25 static comp / 7.8 dynamic comp.

I can 87 octane with no ping. Actually my compression might be a bit lower because I never factored in the volume or space around the piston above the top compression ring. This might add another 1 or 2 cc's.

[uscav_Scout]

Everything was fluxed and double checked by the machine shop, real good guys, more on them in my build thread.
Block was out of a 88 Cherokee, had about 200K miles when it was pulled running, for a V8 swap ($50 off ebay) Not alot of block issues in terms of it being so old, bolted right up for the most part
Alabama Cylinder Head, with hescco performance valves and springs, whopping 62.5cc chambers with spark plug (Part of the reason the block got decked), a performance valve job was done, and the valve seats were cut to bring spring pressures down
Comp Cams 68-235-4 Xtreme 4x4™, X4254H, nice overlap lowered my DCR, Comp Cam lifters, stock push rods and rockers
4.2 Crank, Stock 4.0 rods (out of the 88), kb944s
Block decked to zero, quench was .043 with head gasket
I don't have exact numbers for DCR and SCR (Will do a calc again once I do a proper write up) DCR was prolly around 8.8/8.9, SCR mid 9 to high 9s
26lb Accel Fuel injectors, 01 Manifold w/ 4.7 dodge t-body, I cut a six by six square out of it, had a aluminum plate welded in place(which I painstakingly cut the tbody hole out by hand, made a gasket, mounted map sensor directly behind t-body on plate
Gale banks Header, gibson cat back, hesco high flow water pump, stock thermostat

DCR: 8.38
SCR: 9.40
Runs ping free in April in Illinois on 87 Octane at an elevation of 550 ft ASL
I attribute this to the tight quench, huge combustion chambers (tuliped valves), and the cam. I probably could have gone with the 68-232, but I like the high end power (ridiculous) and it sips on gas on the highway

Attached screens of the data/software used to calc the above values

DCR.png

Timing.png

SCR.png