Just about ready for assembly.... thoughts???

[jamesot]

Just about ready to put the stroker together. Below are the details. Just wanted to run it by the board to see if i may have overlooked anything. All input is more than welcome. Like many othe builds, this stroker stems from a rebuild and with a little research i discovered stroking the motor was not all that much more work or $$$'s. Truck is a daily driver and wheeler. Sees lots of Km's. Also wanted to be able to run on 87 octane fuel (even old fuel from remote outposts and Native reserves way out in the bush). Anyway, here ya go. Truck is a 92' XJ, Auto, 430,000 KM's.... Along with alot of other work.

Build.

Stock 4.0L block 91' (not decked) 0.030 over
Stock 4.0L High Output Head 91' (7120) - ported
258 Crank (1987-90 YJ) ground
258 Rods (1987-90 YJ)
677C Pistons dished to 26cc (bored 0.030 over) Thank-you Oletshot
0.043" head gasket Mopar performance
Late model 1999-2001 intake (ported)
91-95 Throttle body (bored (lower taper removed) and polished)
Cold air intake/Cone filter
Stock 91' Cam and timing
91-95 fuel rail w/39 psi
24.6 lbs/hr @ 39 psi (stock 95 5.3L V8 GC injectors)
New Cooling system
Header (APN/Rugged Ridge style... not a true header but much better flow than stock manifold)
2.5" exhaust
Free flowing cat
Free flowing muffler
(replacing all neccesary engine parts as needed, bearings, timing, oil pump, lifters, rods, etc.)
All bearing work, installation and sizing done by the machine shop

Numbers from the Calculator are as follows.
Deck Height Displacement SCR (X:1) DCR (X:1) Quench

0.0215" 4.59L 8.87 6.58 0.0645

Stock Jeep 4.0L
(0.0215") 3.96L 8.80 6.36 0.725

Have I missed something here or am I all good? Should produce good torque numbers in the low RPM range and get a bit more HP than stock engine. Anyone here ever use the GC injectors for a build? or does everyone use the Ford units? I am betting on the computer being able to adjust to the new injectors and not having to mess with the the MAP or fuel pressure. If I run into issues I can always swap in the Blue tops after.

Well, those who know...... lay it on me?
Cheers,
James

[gradon]

Looks like a good list--just take your time, double check torque specs, use "too much" assembly lube, maybe have an extra set of eyes/hands around, and have fun!

[Mgardiner1]

Connecting rods = 5.875"
half of stroke = 1.9475"
piston height = 1.585"
head gasket = .043"
stock deck height = 9.435

5.875 + 1.9475 + 1.585 = 9.4075

9.435 - 9.4075 = .0275 + .043 = .0705 quench

with stock cam timed at the factory -8 degrees and the compression ratio of Static: 8.78 / Dynamic: 6.51.... you have PLENTY of room to bring the deck height to ZERO, gain a few extra HP and still be well under 7:1 dyncamic compression ratio (READ - Ping free) and sitll produce goobs of torque

Otherwise, enjoy the build while it lasts

[jamesot]

Grandon..... Lube will not be a problem.... lol.

Mgardiner1.... Please go on. I think I need to be educated a bit here...

"with stock cam timed at the factory -8 degrees and the compression ratio of Static: 8.78 / Dynamic: 6.51.... you have PLENTY of room to bring the deck height to ZERO, gain a few extra HP and still be well under 7:1 dyncamic compression ratio (READ - Ping free) and sitll produce goobs of torque"

It appears that my Quench numbers are off.... The block is still at the shop and i can still have as much taken off the deck as i choose. I REALLY need this engine to be ping free....(read Gaurenteed). for the reasons stated above in the original post. However..... i am also not opposed to being completely wrong in my calculations either as i am more akin to messing with suspension angles than I am to playing with engine numbers. In your opinion, what would you suggest to bring the block down to??? What would the Static be? I am not hung up on the static numbers i just know if I keep it below 9:1 I am 99% sure of low grade fuel and no knocks...... bring back the lead I say...lol. I am also aware of the Dynamic magic number of 7:1 as well. I was going to go with the newer model jeep cam and I would have ended up with a better DCR however i am keeping my budget to $2000 CAD incl. custom exhaust work so I decided to keep the 91` as she was in good shape.

Also what are your thoughts in the Injector choice..... I have read some stuf from you and your build and it has helped me to formulate mine.... especially in regard to the injector, computer situation.... as yours seeems to run just fine with the blue ones and the stock comp. and MAP...

I am open to direction from you or others in this respect.... so please let me know what I am not understanding fully.

Cheers,
James

[jamesot]

Mgardiner1..... Just looked at the pic in your sig...... Bumpstop much..... lol.
I am a big fan of Low COG in wheelers.... Looks good. All about the droop!

[ajmorell]

By no means trying to hi-jack, and I didn't see it in the FAQ, but how deep did you have the piston dishes machined to achieve the 26cc vol. on them?

[jamesot]

I had them done by another board member..... see first post.
j.

[Mgardiner1]

If you are trying to keep your build in such a tight budget, then i'm not sure if i'd start squeezing the performance rag However, bringing your quench down to .043 (0.00 deck height) would yield an excellent quench, and still be in the 6.8- range for dynamic compression ratio. Not only do you still have a low DCR which prevents pinging, but you'd also have a very tight quench which also extinguishes pinging, and you'd goose another 5-10ish hp/tq out of it.

Hell i've been running ping free with a .057 quench and 8.25 DCR on 89 octane (haven't tried 87 yet)....

If you bring the cam closer to 0 timing, it will make your DCR go up, so play with the calculator to see what you like. The -8 degrees gives you more low end torque, less upper RPM HP, and 0 timing will give you less low end TQ and more higher RPM HP.

Mgardiner1..... Just looked at the pic in your sig...... Bumpstop much..... lol.
I am a big fan of Low COG in wheelers.... Looks good. All about the droop!

Not sure if i understand your lingo here.... The jeep has a 3.5" lift in that pic.... it has since been raised and will soon be raised a little further.... Maybe the pic is decieving, cause i feel like you are saying it looks lowered instead of lifted? i dunno.

By no means trying to hi-jack, and I didn't see it in the FAQ, but how deep did you have the piston dishes machined to achieve the 26cc vol. on them?

Contact Oletshot with any questions regarding piston dishing. He is the forum GOD for piston machine work.



BTW i got my jeep inspected for the first time with the stroker in it yesterday. It passed Dyno emmisions better then a new car.....

[jamesot]

Took another look at the calc on your recommendation.... gonna keep the -8 on the cam as it achives what I am after. Going to deck the block down to 0.0130 which will be a happy medium i think.... I will discuss with the Machine shop as well. that will give a better quench(0.56) a SCR of 9.01:1 and DCR of 6.68:1.

You are misunderstanding what I said about your rig. It was a compiment to you suspension set-up. I do like a Low Centre of Gravity (COG) in a jeep. Droop ..... is the amount of down travel in your suspension. And the bumpstop comment was from the pic it looks like you have maybe 4" of up travel in your suspension before your tires contact your flares.... bumpstops would be installed to set the upper limit of suspension travel in your setup. I have 33" tires on my cherokee.... with a 4" lift (maybe) and I have the suspension bumpstopped for up travel and gobs of droop in the axle dept. This gets me a Low COG and alot of stability laterally for obstackles and general drivability. not to mention very good drivetrain angles.... Any way I could go on forever..... I like the squat look of your jeep in the pics.... it looks mean.... like a bulldog.

Cheers,
James

[buschguy]

Hey -I'm still a noob myself. I am in the process of picking my recipe. I noticed your Quench is actually 0.0885. You superimposed the stock deck height. It's 9.453 not 9.435. Isn't the magic Q supposed to be between 0.04 and 0.06?

[Mgardiner1]

Hey -I'm still a noob myself. I am in the process of picking my recipe. I noticed your Quench is actually 0.0885. You superimposed the stock deck height. It's 9.453 not 9.435. Isn't the magic Q supposed to be between 0.04 and 0.06?

The 9.450 deck height start in mid-late 90s. i wouldn't be surprised if it was 95-96 when it started. The 87-94 blocks are spec'd out @ 9.435


And thanks for clarifying Jamesot, i felt a little lost

My poor jeep doesn't see enough offroad action anymore (long island is just about nothing but private property...... )

[jamesot]

Too bad about all the private property around your neck of the woods, Almost everything up here is Crown Land with thousands of logging roads to explore and many really good 4x4 trails. I took your advice and when i delivered the pistons to the machine shop i had a conversation with with him about it and he basically agreed with you. He is going to crunch his own numbers and decide how much to deck the block. Keeping in mind the fuel rating concerns, he said zero may not be the best idea however he could most certainly remove some material..... Around 0.0100-0.0130 ish.

On a side note the pistons I recived yesterday from Oletshot were beautiful. Top quality work, completed quickly and at a more than fair price. Thanks again you are a good man. It must be kind cool for you to think about all the Jeeps out there all running your handywork. Cheers.

James