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Low buck stroker recipes

Posted: April 24th, 2019, 11:39 pm
by Xtultegra
What are the pros and cons of these two builds. Why would I choose one over the other?

4.6L Low-buck, low CR "rockcrawler"

Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Custom forged +0.030" bore pistons, compression height 1.380", dish volume 32cc
8.8:1 CR
CompCams 68-115-4 192/200 degree camshaft
DIY ported HO 1.91"/1.50" 57cc cylinder head
Mopar/Victor 0.043" head gasket
0.043" quench height
Ford 24lb/hr injectors for '87-'95 engines, Bosch 0280155703 injectors for '96-'04 engines, '98 Chevy LS1 25.2lb/hr injectors for '05-'06 engines
242hp @ 4600rpm, 317lbft @ 3000rpm

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 4.0 camshaft
DIY ported HO 1.91"/1.50" 57cc cylinder head
Mopar/Victor 0.043" head gasket
0.043" quench height
Ford 24lb/hr injectors for '87-'95 engines, Bosch 0280155703 injectors for '96-'04 engines, '98 Chevy LS1 25.2lb/hr injectors for '05-'06 engines
249hp @ 4900rpm, 303lbft @ 3500rpm ('87-'95 camshaft)
245hp @ 4700rpm, 315lbft @ 3000rpm ('96-'04 camshaft)

Re: Low buck stroker recipes

Posted: April 25th, 2019, 11:33 pm
by Cheromaniac
The rockcrawler is designed with maximum low rpm torque in mind and to run on 87 octane gas year round.
The modified poor man's is a low budget, street oriented build. It still produces excellent low rpm torque but has a little more power at higher rpm. It'll also run on 87 octane gas but you may need a higher grade of fuel in hot weather and when the engine is subjected to higher load.

Re: Low buck stroker recipes

Posted: April 26th, 2019, 11:40 am
by ngrover
Hey Cheromaniac, question on the low buck recipes

1) Can the rockcrawler recipe be tweaked to use a stock cam and still achive a similar outcome in terms of CR and ability to run safely on 87 octane?

2) I have three 4.0 engines ( 93, 97, 99 ) not sure if one has a more desirable OEM cam than the others?

3) Would it be possible to add a "recipe selector" to your calculator so that it will auto-fill the calculator with the values used for each recipe? At the very least it would help me understand how to use the calculator because as it stands I can't seem to replicate the compression ratios listed for the low-buck recipes using the calculator.

Thanks!

Re: Low buck stroker recipes

Posted: April 26th, 2019, 5:33 pm
by Xtultegra
Ngrover- that's a cool idea. Are you saying you would like to see a calculator that you could add some specs into, and it would auto fill the rest to give you a modified recipe that would work within certain parameters. Sounds like a lot of work though!

Re: Low buck stroker recipes

Posted: April 27th, 2019, 12:24 am
by Cheromaniac
ngrover wrote:
April 26th, 2019, 11:40 am
Hey Cheromaniac, question on the low buck recipes

1) Can the rockcrawler recipe be tweaked to use a stock cam and still achive a similar outcome in terms of CR and ability to run safely on 87 octane?

2) I have three 4.0 engines ( 93, 97, 99 ) not sure if one has a more desirable OEM cam than the others?

3) Would it be possible to add a "recipe selector" to your calculator so that it will auto-fill the calculator with the values used for each recipe? At the very least it would help me understand how to use the calculator because as it stands I can't seem to replicate the compression ratios listed for the low-buck recipes using the calculator.

Thanks!
You could just tweak the poor man's stroker recipe by increasing the piston dish to 30cc to drop the compression ratio, but that would also cause a small degradation in performance.
I conceived the rockcrawler recipe with the idea of using a shorter duration cam to maximize low rpm performance but since it's a dual pattern cam, it doesn't give up too much at higher rpm.
Of the OEM cams, the '96+ were designed to shift the torque peak to lower rpm, and that's obvious from the power outputs I quoted for the modified poor man's recipe.

Re: Low buck stroker recipes

Posted: April 30th, 2019, 9:22 am
by ngrover
Xtultegra wrote:
April 26th, 2019, 5:33 pm
Ngrover- that's a cool idea. Are you saying you would like to see a calculator that you could add some specs into, and it would auto fill the rest to give you a modified recipe that would work within certain parameters. Sounds like a lot of work though!
Hey Xtultegra,

What I was thinking was along the lines of having a selector/drop-down in the calculator where you would see a list of known build recipes as follows:
  • 4.6L Low-buck, low CR "rockcrawler"
  • 4.6L Modified "poor man's" stroker
  • Original "poor man's" stroker
  • 4.2L Milder mini-stroker
  • 4.2L Wilder mini-stroker
  • 4.7L medium-buck stroker
  • 4.8L high-buck stroker
  • 4.9L high-buck stroker
  • 5.0L very high-buck stroker
When you select one of the above options, the calculator would be populated with all the values related to that build recipe.

The builds are outlined here: http://www.jeep4.0performance.4mg.com/stroker.html

From the link above you can see for example the recipe for the "4.6L Modified "poor man's" stroker" which currently looks like this:
Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Custom forged +0.030" bore pistons, compression height 1.380", dish volume 32cc
8.8:1 CR
CompCams 68-115-4 192/200 degree camshaft
DIY ported HO 1.91"/1.50" 57cc cylinder head
Mopar/Victor 0.043" head gasket
0.043" quench height
Ford 24lb/hr injectors for '87-'95 engines, Bosch 0280155703 injectors for '96-'04 engines, '98 Chevy LS1 25.2lb/hr injectors for '05-'06 engines
242hp @ 4600rpm, 317lbft @ 3000rpm

The CR in the above recipe is said to be 8.8:1 so I would expect that when I select that build recipe in the calculator then the numbers would line up and the CR would match 8.8:1. The point being that I could then have a baseline in the calculator and fiddle with the numbers to my liking to come up with my own build based off of one of the known recipes. Hope that makes sense.

Re: Low buck stroker recipes

Posted: April 30th, 2019, 9:29 am
by ngrover
Cheromaniac wrote:
April 27th, 2019, 12:24 am
You could just tweak the poor man's stroker recipe by increasing the piston dish to 30cc to drop the compression ratio, but that would also cause a small degradation in performance.
I conceived the rockcrawler recipe with the idea of using a shorter duration cam to maximize low rpm performance but since it's a dual pattern cam, it doesn't give up too much at higher rpm.
Of the OEM cams, the '96+ were designed to shift the torque peak to lower rpm, and that's obvious from the power outputs I quoted for the modified poor man's recipe.
Thanks Cheromaniac,

I think I would go that route ( stock 96+ cam with 30cc dish and the rest the same as the 4.6L Low-buck, low CR "rockcrawler" ).

The stock cam is appealing because I have a couple in good shape already (keep expense down) and I don't want to worry about longevity / cam retainer failure etc. I also want to comfortably live in the 87 octane zone. I'm ok with loosing a bit of performance for these reasons.

Re: Low buck stroker recipes

Posted: May 11th, 2019, 2:15 am
by Xtultegra
Cheromaniac wrote:
April 25th, 2019, 11:33 pm
The rockcrawler is designed with maximum low rpm torque in mind and to run on 87 octane gas year round.
The modified poor man's is a low budget, street oriented build. It still produces excellent low rpm torque but has a little more power at higher rpm. It'll also run on 87 octane gas but you may need a higher grade of fuel in hot weather and when the engine is subjected to higher load.
Would decking the block help the modified poorman's stroker recipe? Would I then change piston dish also?

Re: Low buck stroker recipes

Posted: May 11th, 2019, 10:35 am
by Cheromaniac
The whole idea behind the modified version of the poor man's recipe is that you use custom pistons with the correct compression height, and the correct piston dish volume for the desired compression ratio, so that you WON'T need to deck the block.
If you want to raise or lower the compression ratio, just specify a different piston dish volume.

Re: Low buck stroker recipes

Posted: May 12th, 2019, 11:25 pm
by Xtultegra
Cheromaniac wrote:
May 11th, 2019, 10:35 am
The whole idea behind the modified version of the poor man's recipe is that you use custom pistons with the correct compression height, and the correct piston dish volume for the desired compression ratio, so that you WON'T need to deck the block.
If you want to raise or lower the compression ratio, just specify a different piston dish volume.
So decking a block will give you the same performance gains as choosing a custom piston with less dish? Sorry if this is a stupid question. Just trying to learn as much as possible before spending so much money.

Re: Low buck stroker recipes

Posted: May 13th, 2019, 10:09 pm
by Russ Pottenger
Xtultegra wrote:
May 12th, 2019, 11:25 pm
Cheromaniac wrote:
May 11th, 2019, 10:35 am
The whole idea behind the modified version of the poor man's recipe is that you use custom pistons with the correct compression height, and the correct piston dish volume for the desired compression ratio, so that you WON'T need to deck the block.
If you want to raise or lower the compression ratio, just specify a different piston dish volume.
So decking a block will give you the same performance gains as choosing a custom piston with less dish? Sorry if this is a stupid question. Just trying to learn as much as possible before spending so much money.
No such thing as stupid questions

I stock pistons in .030/4.6 and .060/4.7 with piston dish volumes from 12cc to 30cc in 2cc increments While at the same time not necessarily having to surface the deck of a block in order to maintain a positive piston to deck.

Welcome to contact me for further information and pricing.

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