07NBSChevy

iTrader: (1)

So I will be sending in my 243s to PRC to have a mild port along with having them milled and have a few questions.

I currently have a Gen 4 LMG 5.3 with OE 243 heads, Crane 210/218---.551/.551---116+2LSA---110ICL cam, Stock flat top pistons, 051" MLS head gaskets.

I would like to have the PRC Stage 2.5 done to the heads, have the heads milled down to 58CC Combustion Chamber (.0036" Milled give or take), using Ferrea 2.02" Intake and 1.575" Exhaust valves. Also going to a .040" head gasket to achieve a 11.12:1 Static CR and a 8.15:1 Dynamic CR.

My question is will I run into any PTV clearance issues or any issues of any sorts with this combo?
I want to stay away from Fly Cutting the pistons. SO if something needs to be changed let me know. I can have the heads shaved .030" to be at 59CC's if needed.

Thanks in advance

hiltsy855

iTrader: (35)

It never hurts to check but you should be fine milling ~.036" with that lift.

redtan

iTrader: (5)

Are you sure about those cam specs and compression results?

With 58cc chambers, flat tops and a 110ICL cam those compression numbers seem off.

07NBSChevy

iTrader: (1)

I have used 3 different calculators and came up with 11.1-11.2:1 Static and 8.15-8.21:1 on Dynamic.

I am using a 3.780" Bore, 3.622" Stroke, Cylinder head Gasket Bore of 3.92", Head gasket thickness of .040", 58cc Chamber, Stock Gen 4/L33 Flat top pistons 0.00CC , -.006 Piston Deck Clearance out of hole.

Cams ABDC is at 74.0, 0 Boost at Sea Level.

Did I miss something or didn't calculate something right?

I am 100% Sure on cam specs, looking at cam card now. Crane Cams # 1449051

Factory specs on Static CR is 9.95:1 with stock 64.45CC 243s and .051" head gasket.

07NBSChevy

iTrader: (1)

Does anyone have a good website to calculating the Static Compression Ratio. I have tried 10 different places and it varies from 10.89 up to 11.38:1 using all the same specs.

07NBSChevy

iTrader: (1)

http://www.rbracing-rsr.com/compstaticcalc.html
http://www.wallaceracing.com/dynamic-cr.php

I used RBRacings thing and came up with 11.2:1 SCR with a 59cc Camber and .040" head gasket, then used Wallace Racing for the DCR and came up with 8.21:1

Does this sound right for a 59cc chamber? The 58cc with these calculators puts me above the DCR I would like to be at.

07NBSChevy

iTrader: (1)

Does this seem about right?

redtan

iTrader: (5)

You're using duration and valve events at 0.050...that's not going to be accurate. Plus, that number should be 39 + 15 so 54 if you're going by that. Idk where you got 74 from.

You need to look at the advertised duration at 0.006

11.2 SCR with 272 advertised duration and 114ICL is about 8.53.

Although it's confusing, you're saying 116+2 but the ICL is 110?

07NBSChevy

iTrader: (1)

Roger vinci sent me all the specs on the cam and it clearly says 110 intake center line. Maybe he made a mistake.

The 74 ABDC at .004" , i honestly did not know their was a difference.

gagliano7

Its probably 116+4. I have a 222/226 115+3 .600 lift and PRC 5.3 heads 58cc on a 5.3 LM7 and i have no issues.

07NBSChevy

iTrader: (1)

To many damn numbers at different durations, so confusing and i thought i had most of it down.

07NBSChevy

iTrader: (1)

Its a 116+2 for sure. I know that for a fact. Just the ICL, i emailed roger about it and he emailed me back a hand written cam card and it said 110. Probably a mistype.

redtan

iTrader: (5)

Those don't make sense. The only way I got to match his valve events at 0.004 is with a 116-2 actually, so a 118 ICL.

Sorry to jump off course here, in the end this cam will work fine in your situation.

07NBSChevy

iTrader: (1)

Interesting. This is confusing. Maybe everything is wrong about his cam card.

I am going to email him back and try and get the right specs.

07NBSChevy

iTrader: (1)

I sent him an email about this and he said it is a 116 with 2 degrees of advance. And said the ICL is unadvertised. No idea what that means. But it is for sure a 116+2.

07NBSChevy

iTrader: (1)

Redtan, i do appreciate your replys and knowledge on this. I am still trying to understand all this cam stuff.

Based off all the info on the cam I gave you minus the ICL, what would be the best chamber size to achieve the closest to 8.2:1 dynamic compression.

07NBSChevy

iTrader: (1)

Now I did find more info on the cam, overlap being 48 if that helps any.

redtan

iTrader: (5)

Honestly, I would go with another cam that is better spec'd...or manually advance the current one.

I would shoot for something like 8.5-8.6 DCR. That could be achieved by milling off 2-3ccs of the heads.

07NBSChevy

iTrader: (1)

Cam you recommend a cam that you have heard good about. I do not want to change to converter since I tow 6600lbs once a month. What about a BTR truck stage 2 or TSP 212/218 .550/.550 114LSA?

redtan

iTrader: (5)

Both of those are good choices, I would go with the BTR on Cammotion cores.