New 4.2L mini-stroker recipes

[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

[jpradcliffe]

You Da Man! Thank You!

[jpradcliffe]

I ordered these.

https://www.walmart.com/ip/17113553-Bla ... /760075977

Normally never shop at walmart but $10 injectors, i can do!

[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.

[TJryder]

I ordered these.

https://www.walmart.com/ip/17113553-Bla ... /760075977

Normally never shop at walmart but $10 injectors, i can do!

Is Walmart paying for engine rebuild if injector is not squirting enough fuel and lean & hot mixture burn blows your piston?

[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.

[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.

[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! "

[Russ Pottenger]

Your machine shop is installing the valve springs at the incorrect spring height

[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

[Cheromaniac]

Looks good. With a modest 9.15 SCR plus a tight quench height, it should run on 87 octane fuel.

[jpradcliffe]

Yeah. Well it is much less compression than I was hoping for but oh well.

[Russ Pottenger]

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

[Cheromaniac]

IIRC the Silvolite 2229s are 11.5cc if those are the Pistons he's using.

[Russ Pottenger]

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