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Re: New 4.2L mini-stroker recipes
Posted: April 24th, 2019, 12:28 am
by Cheromaniac
Your fuel system runs at a fuel pressure of 39psi. If you're aiming at 260-270hp you're going to need injectors that flow 26-27lb/hr at 39psi, and these fit the bill:
https://www.amazon.com/28lb-Injectors-C ... B0721CWH28
Re: New 4.2L mini-stroker recipes
Posted: April 26th, 2019, 5:29 pm
by jpradcliffe
You Da Man! Thank You!
Re: New 4.2L mini-stroker recipes
Posted: April 30th, 2019, 8:19 pm
by jpradcliffe
I ordered these.
https://www.walmart.com/ip/17113553-Bla ... /760075977
Normally never shop at walmart but $10 injectors, i can do!
Re: New 4.2L mini-stroker recipes
Posted: May 1st, 2019, 5:12 pm
by SkylinesSuck
Not knocking them, and I'm all for using cheap "Chinese" crap when warranted. Just be aware Walmart is going "amazon" and using it's site to sell stuff from Walmart along with just being a front for other people to sell their own stuff now. They may or may not stand behind things they still FWIW.
Re: New 4.2L mini-stroker recipes
Posted: May 3rd, 2019, 11:41 am
by TJryder
Is Walmart paying for engine rebuild if injector is not squirting enough fuel and lean & hot mixture burn blows your piston?
Re: New 4.2L mini-stroker recipes
Posted: May 4th, 2019, 9:12 pm
by jpradcliffe
Geez Louise.
Hey Cheromaniac and or Russ: what kind of minimum flow numbers do I need out of my ported head to achieve said 270 plus horsepressures? Please advise. Thank you.
Re: New 4.2L mini-stroker recipes
Posted: May 4th, 2019, 11:41 pm
by Cheromaniac
These are the flow numbers for Russ' ported stock head with LS1 valves:
Russ Pottenger ported 2.00/1.55 HO head #7120
Valve lift (in)... 0.1 ... 0.2 ... 0.3 ... 0.4 ... 0.5 ... 0.6
Intake flow.... 75.5 138.0 194.0 235.0 261.0 276.0
Exhaust flow. 59.6 106.3 153.3 180.7 193.4 198.8
Those are pretty amazing numbers when you consider that a stock head flows ~209/141 @ 0.50" valve lift.
Re: New 4.2L mini-stroker recipes
Posted: May 16th, 2019, 1:24 pm
by jpradcliffe
Hey experts. I got this msg from my machine shop today. What say ye?
"AFTER CHECKING THE VALVE SPRINGS THAT YOU SUPPLIED, WE GOT THE FOLLOWING
PRESSURES. WE GOT 130 LBS @ 1.600 INSTALLED AND 310 LBS @ .494" LIFT.
ALSO, WE HAVE .039" TO .072" COIL BIND. IN MY OPINION, THE PRESSURES
SEEM TO BE A LITTLE EXCESSIVE FOR THE STREET ON A HYDRAULIC FLAT TAPPET
CAMSHAFT. LET ME KNOW WHAT YOU THINK AND WE'LL GO FROM THERE! "
Re: New 4.2L mini-stroker recipes
Posted: May 17th, 2019, 8:37 am
by Russ Pottenger
Your machine shop is installing the valve springs at the incorrect spring height
Re: New 4.2L mini-stroker recipes
Posted: May 29th, 2019, 1:31 pm
by jpradcliffe
Well, motor is done. Sitting in my garage. Yippie!
Here is how it turned out.
Russ & Dino, what do you think?
20190529_162647.jpg
Re: New 4.2L mini-stroker recipes
Posted: May 31st, 2019, 2:43 am
by Cheromaniac
Looks good. With a modest 9.15 SCR plus a tight quench height, it should run on 87 octane fuel.
Re: New 4.2L mini-stroker recipes
Posted: May 31st, 2019, 8:04 am
by jpradcliffe
Yeah. Well it is much less compression than I was hoping for but oh well.
Re: New 4.2L mini-stroker recipes
Posted: June 1st, 2019, 1:50 pm
by Russ Pottenger
jpradcliffe wrote: ↑May 31st, 2019, 8:04 am
Yeah. Well it is much less compression than I was hoping for but oh well.
Your static might be slightly higher than you calculated.
I could be wrong but I think the Silvolite pistons are closer to 12cc’s than 15
If it’s not too late keep in mind you could always surface the head. With a tight quench and correct cam, with enough injector a static of 9.4:1 / 9.5:1ish is still pretty safe on 87
Re: New 4.2L mini-stroker recipes
Posted: June 1st, 2019, 11:36 pm
by Cheromaniac
IIRC the Silvolite 2229s are 11.5cc if those are the Pistons he's using.
Re: New 4.2L mini-stroker recipes
Posted: June 2nd, 2019, 1:26 pm
by Russ Pottenger
Cheromaniac wrote: ↑June 1st, 2019, 11:36 pm
IIRC the Silvolite 2229s are 11.5cc if those are the Pistons he's using.
Thanks for clarifying that Dino.
That’s what I had in my notes for the dish volume on the 2229 piston.
I believe that is what Josh is running and it’ll up his static compression ratio calculations more in line what he’s looking for