I think i might be crazy

[jason_alex_2009]

Hey guys I know I am probably crazy but i am wanting to build a stroker that can run on 87 without pinging. As this will be my DD and i will be driving 80 miles a day on it.

Here is my plan and please let me know what problems you see. but the whole plan is to run 87 i know plans dont always work out

4.0 rods
KB icon 944 forged pistons +.030 wall clearance around .0035 21cc dish
+24 lb/hr injector
I am going to be running right at 700-900 ft above sea.
4.2 4 wt crank
.043 thickness victor mls
I will do a diy hand port job on the intake and exhaust as well as clean up the combustion chamber
I am planning on my 2002 4.0 block bore line hone and i am looking at decking here is where I am getting fuzzy that the lower quench height give you a better chance of preventing pinging but it would put my dcr around 9.85 and a static at 8.5 that seams a little high to be running 87 but it ways said on http://www.jeep4.0performance.4mg.com/stroker.html that the modified poor mans stoker could run on 87 granted they are running 26cc dish pistons

It seams like every problem i read about is related to cam and springs. this is why i want to stay with a stock cam and springs, and i want to use my thrust plate to hold my cam in place. to keep is as reliable as possible.

Dose anyone have a stroker with 4.0 rods and 944 pistons and what gas do you guys run?

Thanks,
Jason

[dwg86]

You could have jones cams, or bullet cams grind a custom cam using a new cam blank made for the cam plate block. Russ Pottenger (machinist and member on the forum) says the 4.0 replacement valve spring VS-1456 will drop in without any machining required and is good to .475 lift.
So you could have a custom cam ground with 208-212 duration @ .050 with up to .475 lift, 110-112 valve overlap? Keep your stock valve springs and the reliability of the stock 4.0.

[optmaxx]

I run KB 944 .020 over, stock aftermarket 91-95 cam and the Felpro heavy duty head gasket pt#530SD; with no pinging on Arco 87 gas. I run 89 just to be safe, but I've had no pinging issues on 87 or 89, and my Jeep is my DD.

[jason_alex_2009]

What's your quench height feel pro isn't that a .051 gasket? What altitude are you at? Did you port your head?

[Russ Pottenger]

Unfortunately there's a lot of compromises built-in to the 944 piston.
1. You're stuck with a 21 cc dish
2. To get anything even remotely close to an adequate
quench you will need to surface your block something
around .045 Unless you open up your chambers, that
will be a problem running on pump gas.
3. Not having an option to run a bush Rod.

My shelf forged pistons range from 20cc to 28cc
With custom compression hight options.
Between the two common head gasket options of .051 and .043 you'll have the option of A minimal block surface to nothing at all.

Just a few days ago I received my new connecting rod forgings. They are a steel I-beam forging. The caps are located by stainless dowels held together by 3/8 8740 Capscrew rod bolts. The latest forgings come with no balance pad on either end of the rod. Anybody that has had to clearance the factory main stud girdle in a stroker knows what a hassle it can be.

Lastly my rods come bushed allowing for a much lighter and stronger .927 Chevy wrist pin. If the Pistons are purchased with my rods I'll upgrade the pins at no additional cost.

I'm currently selling my Pistons for $495.00 a set, and Connecting Rods for $325.00

If you factor in the cost of rebuilding a cast 4.0 rod, upgrading to a replacement 11/32 ARP bolts, balance them end to end, Pay your local machine shop to press your old Pistons off and install the new Press fit pistons, in most parts of the country you'll be within $60-$70 have a pretty significant upgrade in my rods.

Feel free to drop me an email or call and I'll be happy to send you pictures and information of my Pistons, Rods, and any of my specialty components. Everything from my ported cylinder heads, custom cams to my custom stroker engine kits.

Russ Pottenger
Bishop-Buehl Racing Engines
531 N. Lyall Avenue
West Covina, California 91790
Work (626) 967-1000
Fax (626) 967-7836
Cell (626) 673-2203
Email/PayPal: [email protected]

[jason_alex_2009]

That is amazing you can get between 20 and 28cc pistons, If i didnt already have the IC944 i would defiantly gone thought way right now the only thing i have is 4.2 scat crank 4.0 rods and 944 pistons i bought about 2 years ago when my engine told me it had 0 oil pressure since then i have been getting parts like a 4.0 block and working on it when i could well. well my motor finally went out and new i am scrambling to get it done and trying to find any way i can to get it to run 87. I think it blew the head gasket, I am pulling that motor apart to see what it did and try and bandage it back togeter to get some more time for the stroker.

[Russ Pottenger]

Jason,

You'll be fine. You're going to need to deck about .045 off the deck of the block zero to .005 out with a .043 gasket and get the chambers to 62cc. Putting in the Chevy LS valves will help you get there.
.038 to .040 piston to head at just under 9.5:1 will run great on 87 with a butt load of torque with the right cam.

[jason_alex_2009]

The chambers on the 0331 heads are only 56.6 to 57 wont it be a lot of material to remove to get to 63cc? I am considering getting ride of the 944 and getting some of your 28cc I dont care about getting the tip top performance ill give up 25hp all day to run 87 for my DD. and the cost over the life of the motor from 91 to 87 would be less than the cost of the pistons.

[jason_alex_2009]

using the stroker calculator it says the factory deck clearance is .0215 is this correct? so it would cutting the deck below 0 and adding the thickness of the gasket to make up the extra distance, isnt that kinda risky at higher rpm?

[Russ Pottenger]

We are shooting for something around a 9.450 deck height with a piston CD of 1.385

[optmaxx]

What's your quench height feel pro isn't that a .051 gasket? What altitude are you at? Did you port your head?

I live in San Diego, so I guess my altitude is at 62'? I could never figure that part out in the stroker calculator. I didn't deck my block from a '96 4.0, so I think my quench is in the 70s...I can't remember, but I know that it's not desirable. Yes, that Felpro gasket is thicker; probably lowering my compression, and I didn't port my head.

I was at my rope's end when I decided to go with the KB 944s because of a failed first attempt at a stroker build, and I already had the KBs laying around so I went with those. I didn't even care if I needed to run 91 gas because I just wanted my car back, but it all worked out in the end, and I seem to be doing fine with 87-89 gas. I can't tell you why it doesn't ping, but I'm not going to recommend doing it my way either, and if I could start back at step one, I would have ordered stuff from Russ. I am happy with my stroker, it definitely feels like it has more torque than my old 4.2 and my dad's 4.0, so no regrets. Just putting in my experience, but don't go my route.

[jason_alex_2009]

This is what i was thinking about doing to try and get my cr down, but after looking at it i think i will have the block decked go with a .043 gasket and try to open up the combustion chamber to drop cr are you running a stock cam? and valves? I would also order the bigger dished pistons if i could go back and i still might. I would really like to run the kb 944 with 87 who knows maybe i can get lucky with the 62cc and drop T-state to a 170 degree instead of he 190 thats in it now.

[optmaxx]

This is what i was thinking about doing to try and get my cr down, but after looking at it i think i will have the block decked go with a .043 gasket and try to open up the combustion chamber to drop cr are you running a stock cam? and valves? I would also order the bigger dished pistons if i could go back and i still might. I would really like to run the kb 944 with 87 who knows maybe i can get lucky with the 62cc and drop T-state to a 170 degree instead of he 190 thats in it now.

Yeah I got the stock 91-95 cam with the cam button, and only because I have the timing cover made for the cam button application, and stock valves. Going with a tighter quench will give you a stronger more efficient engine, so just go with Russ. I wouldn't recommend doing what I did cause it's a gamble, so if you have a chance to order better custom parts, and build a stronger engine for just a few bucks more, do it--I would. Also, I don't think putting a lower temp T-stat would help with pinging, your engine will eventually reach it's operating temp even with a lower T-stat; it would just take a little longer; I run a stock temp T-stat.

Like I said, I can't explain why my stroker isn't pinging--and I know what pinging sounds like--but professional builders here can explain what will keep your stroker from pinging, so listen to them.

[Cheromaniac]

You could do the modified poor man's stroker using your existing stock cam. With a modest SCR and tight quench it'll run on 87 octane and be a nice, torquey motor that's perfect for a daily driver. With all that lovely low rpm torque you'll get good highway gas mileage too.

4.6L Modified "poor man's" stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Custom forged +0.020" bore pistons, compression height 1.380", dish volume 26cc
9.25:1 CR
Stock '96-'04 camshaft
DIY ported HO 1.91"/1.50" 57cc cylinder head
Mopar/Victor 0.043" head gasket
0.043" quench height
Bosch 0280155703 injectors for '96-'04 engines
245hp @ 4700rpm, 315lbft @ 3000rpm ('96-'04 camshaft)

[jason_alex_2009]

Thats showing 26cc dished pistons but if you open up the combustion chamber should be the done by a machine shop or just very slow and re cc every few mins to make a smooth combustion chamber?