Did I Get the Right Stroker?

[Border Dave]

Wouldn't it be easier and more economical to just have them dish the pistons to say, 26cc?

[Cheromaniac]

You could get the same 8.7:1 CR by not milling the block at all and dishing the pistons to 23cc, but the quench will be a high 0.093".

[Border Dave]

You could get the same 8.7:1 CR by not milling the block at all and dishing the pistons to 23cc, but the quench will be a high 0.093".

Please pardon my ignorance, but is that a bad thing?

[Cheromaniac]

It won't harm the engine but the high quench will make the engine more prone to pinging and it might not like 87 octane even with a modest 8.7:1 SCR.

[Border Dave]

Keep in mind that after milling the block deck you'll need 0.025" shorter pushrods than stock (stock are 9.625" so yours would need to be 9.600").

I see you didn't list that detail in your engine specifications. Are there any other custom modifications that must be done? I'm in the process of trying to get ahold of the engine builder to let them know. My confidence in this company is fading.

[Cheromaniac]

I see you didn't list that detail in your engine specifications.

That's right. I didn't 'cause there's an alternative to shorter pushrods, and that is to add 0.030" shims under the rocker arm bridges instead.

[Border Dave]

I told the engine builder I wanted this motor:

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

That's the old version of my rockcrawler recipe. This is the current one:

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 for '87-'95 engines, Accel 24lb/hr injectors for '96-'04 engines, '98 Chevy LS1 25.2lb/hr injectors for '05-'06 engines
240hp @ 4700rpm, 315lbft @ 3000rpm

If you assume a head chamber volume of 57cc, piston dish volume of 30cc, head gasket volume of 9cc, and a deck clearance volume of 3cc (after milling 0.035" off the block deck), the total combustion volume is 99cc and the SCR is 8.72:1.

Why do you recommend Accel injectors with my 2001 engine?

[Border Dave]

OK, Dino, I think I found the answer in your post on JU from 10 years ago. It looks like the Accel injectors flow less fuel than the Ford ones.

The Accel injectors will do the job very nicely. The only difference between these and the Ford injectors is that the Accels flow 24lb/hr at 43.5psi (22.7lb/hr at 39psi) whereas the Fords flow 24.0lb/hr at 39psi.

If I get the Accel injectors, won't I need the plug adapters for my 2001 Wrangler?

[Cheromaniac]

If I get the Accel injectors, won't I need the plug adapters for my 2001 Wrangler?

Yes, you'll need a set of EV1 to EV6 adapters and you can get them from Summit Racing. They don't cost much.

[Border Dave]

Great! I'll order the injectors and adapters from Summit today so my mechanic will have them by the time I get my motor back from the builder. With my 2001 Wrangler, what's involved in getting it to run right? I've heard that I'll have to adjust the MAP? Anything else that I need?

[W_A_Watson_II]

I told the engine builder I wanted this motor:

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

That's the old version of my rockcrawler recipe. This is the current one:

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 for '87-'95 engines, Accel 24lb/hr injectors for '96-'04 engines, '98 Chevy LS1 25.2lb/hr injectors for '05-'06 engines
240hp @ 4700rpm, 315lbft @ 3000rpm

If you assume a head chamber volume of 57cc, piston dish volume of 30cc, head gasket volume of 9cc, and a deck clearance volume of 3cc (after milling 0.035" off the block deck), the total combustion volume is 99cc and the SCR is 8.72:1.

DISCLAIMER, this is my first post here, and I'm in the planning states of building my first stroker.

Cheromaniac,

If the new recipe with only the Cam change, does the Torque change from 327lbft @ 2000rpm to 315lbft @ 3000rpm, or is the original recipe torque perdition in error?

I'm looking for the best low end torque in my build and was starting with your older recipe.

Thanks,
Will

[Border Dave]

Dino,

I just spoke to my builder and he wanted me to ask you a question. On the Rockcrawler motor, he wanted to know how you're getting the .058" quench. "Is it measured from the head gasket to the top of the piston or from the deck of the block to the top of the piston?"

David

[Retlaw01XJ]

[quote="Border Dave"]Dino,
"Is it measured from the head gasket to the top of the piston or from the deck of the block to the top of the piston?"

David[/quote

I'm not Dino, but I learned a LOT from him!...

Quench is the distance between the flat portion of the piston's outer edges and the flat portion of the cylinder head.
It would be equal to the deck clearance (amount piston is below the deck surface at TDC) plus the thickness of the compressed head gasket.

[Cheromaniac]

DISCLAIMER, this is my first post here, and I'm in the planning states of building my first stroker.

Cheromaniac,

If the new recipe with only the Cam change, does the Torque change from 327lbft @ 2000rpm to 315lbft @ 3000rpm, or is the original recipe torque perdition in error?

I'm looking for the best low end torque in my build and was starting with your older recipe.

Thanks,
Will

Will,
My torque estimate for the original rockcrawler recipe may have been a bit optimistic. The newer recipe should be nearly as good at lower rpm but slightly better higher up.

Dino,

I just spoke to my builder and he wanted me to ask you a question. On the Rockcrawler motor, he wanted to know how you're getting the .058" quench. "Is it measured from the head gasket to the top of the piston or from the deck of the block to the top of the piston?"

David

The 0.058" quench is the sum of the head gasket compressed thickness (0.043") and the deck clearance (0.015"). The deck clearance is the distance that the flat portion of the piston crown sits below the block deck when the piston is at TDC. In order to achieve a deck clearance of just 0.015" when using the 258 crank/rods and Silvolite 2229 pistons in the 4.0L block, the block deck needs to be milled by 0.035".

Quench is the distance between the flat portion of the piston's outer edges and the flat portion of the cylinder head.
It would be equal to the deck clearance (amount piston is below the deck surface at TDC) plus the thickness of the compressed head gasket

Spot on.

[Border Dave]

You guys are great! Thanks a lot! I can't wait to get this engine back.