Did I Get the Right Stroker?

[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

They said they offer a very similar engine that I could still use 87 octane in, so I had them use my block as a core and they built it. Here are the specs they finally gave me after I had to repeatedly ask them for the build sheet:

Size: 288
Camshaft: Stock - 991L
Rod Size: 10 Main Size: 10
Bearings:
Rods: 10
Mains: 10
Torqued Mains: 85
Torqued Rods: 35
Piston Part#: E309H
Bore Size: 30
Head Casting#: New 110 lbs L - Front 100 lbs.
Lifters: 2011
Push Rods: 437
Rockers: 740
Fulcrums: 1717

They had a new Alabama Cylinder Head in stock, so I had them send it out to be ported and polished, but they didn't send any info about that, other than what I typed above.

Does this sound like a reliable motor that I can run 87 octane in? How much horsepower/torque should I expect?

[gradon]

It's gonna be a 280cu.in. with a .030" overbore. I don't know the individual part numbers, and have never seen the E309H piston written down. If they know how to build engines, building up a jeep inline six is cake.
edit: Caldwell hypereutectic pistons for 96-00 4.0s(metric). never heard of em, but they are cheaper than Sealed Powers(Federal Mogul) and KBs. You might want to get a dish and pin height spec on em cause they might only have a 11cc dish. You should tell them to zero-deck the block.

[Border Dave]

I just got off the phone with the sales manager and they sent me a high compression ratio engine that requires 92 octane. When I ordered it, the salesperson assured me it had fairly low compression (8.9), but now it appears it is 9.8. I had the sales manager look at the specs on the Rockcrawler motor I listed above and he doesn't know how it only has 8.8 compression. With the figures listed, he says it's impossible that its compression is that low, but he's willing to take my engine back and dish the pistons some more.

I don't know what to do at this point. This is my daily driver. Does anyone know how the "Rockcrawler" motor listed above has only 8.8 compression?

[SilverXJ]

I don't know what to do at this point. This is my daily driver. Does anyone know how the "Rockcrawler" motor listed above has only 8.8 compression?

Silvolite UEM-2229 +0.030" bore pistons
Increase piston dish volume to 30cc

That should answer the question about how it can make low compression.

Who is this engine builder?

[Border Dave]

The builder is S & J Engines out of Spokane, WA. The sales manager said they use the 2229 pistons and that just dishing the pistons wont lower the compression that much.

[SilverXJ]

The 2229 Piston has a 11.5cc dish stock, which is pretty much the smallest dish available on an aftermarket piston. Putting that into the calc (w/o decking the block, as it wasn't listed in what they did) yields a 10.08:1 SCR for a .030" over stroker.

Using a 30cc dish w/ all else the same yields a 8.44:1 SCR. 1.64 points lower, which is quite a bit.

Someone obviously didn't do the math to figure that out.

[Border Dave]

The 2229 Piston has a 11.5cc dish stock, which is pretty much the smallest dish available on an aftermarket piston. Putting that into the calc (w/o decking the block, as it wasn't listed in what they did) yields a 10.08:1 SCR for a .030" over stroker.

Using a 30cc dish w/ all else the same yields a 8.44:1 SCR. 1.64 points lower, which is quite a bit.

Someone obviously didn't do the math to figure that out.

Is your figure of 8.44:1 different from the "Rockcrawler" motor's compression ratio of 8.8:1 because the Rockcrawler uses a milled block and a thinner head gasket?

They told me they didn't mill the deck of the motor they sent me. So what do I need to do? Send the engine back and have them switch out the pistons for ones with a 30cc dish? Or is that custom work that they'll need to farm out? If I get them to do that, will I be able to use 87 octane gasoline?

Also, on my 2001 motor, I would be able to use the factory fuel injectors, wouldn't I?

[SilverXJ]

Is your figure of 8.44:1 different from the "Rockcrawler" motor's compression ratio of 8.8:1 because the Rockcrawler uses a milled block and a thinner head gasket?

Yes. zero deck clearance w/ a /043" head gasket yields a 8.89:1 DCR.

So what do I need to do? Send the engine back and have them switch out the pistons for ones with a 30cc dish? Or is that custom work that they'll need to farm out?

I don't know what to tell you there. You either should run 91 octane or change something

If I get them to do that, will I be able to use 87 octane gasoline?

Can't tell you for certain.

Also, on my 2001 motor, I would be able to use the factory fuel injectors, wouldn't I?

NO! The two I recommend are the Bosch 0-280-155-784 (Neon) and Mopar 53032704AB (used in a 04-06 Jeep 4.7L HO). They have worked the best on my 49 PSI rail. Stock injectors on an otherwise stock system (no MAP sensor mod or anything of the like) will create major problems. And just because you may not head ping at WOT doesn't mean its running very lean and heating stuff up.

[Border Dave]

Thanks a lot for the info, guys. It's been really helpful. Do both of the fuel injectors you listed need plug adapters to make them work in my 2001 TJ?

I'd still like to know more about what I need to have done to the pistons in order to use 87 octane. Anyone else have any opinions on what I should do?

[SilverXJ]

No, they are a direct drop in. I run the Neons, but I saw no difference from the Jeeps.

You need to make the decision if you want to run 91 vs. running 87 and pulling the engine apart.

[Border Dave]

I spoke with the sales manager and he's having the engine shipped back to them and will change out the pistons for the Silvolite UEM-2229s. It sounds like he's going to have his shop dish them out to 30cc so I have a lower compression ratio.

[Border Dave]

[quote="SilverXJ"
Using a 30cc dish w/ all else the same yields a 8.44:1 SCR. 1.64 points lower, which is quite a bit.
[/quote]
Would 8.44 compression be too low? If so, should I have them either dish the pistons only 26cc (give or take) or have them install the thinner Mopar Performance head gasket?

I still don't understand exactly what "decking the block" is or does.

[Cheromaniac]

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.

[Border Dave]

Thanks for the info on the updated Rockcrawler engine.

It looks like my builder put a lot of OEM spec parts into the engine. When I spoke to the builder today, they said they are changing the pistons to the Silvolite 2229s and will have them dished accordingly so that I can use 87 octane fuel. They didn't do any milling to the deck and are using the factory head gasket, not the Mopar Performance one. The cam is a stock cam, but I did get them to port the Alabama cylinder head.

Do you think this will be a decent motor or should I have them change anything else while it's in the shop?

[Cheromaniac]

They didn't do any milling to the deck and are using the factory head gasket, not the Mopar Performance one. The cam is a stock cam, but I did get them to port the Alabama cylinder head.

Do you think this will be a decent motor or should I have them change anything else while it's in the shop?

Yeah, if they successfully dish the pistons to 30cc, ask them to mill the block deck so you won't end up with a very low compression motor and a high quench. 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").