jermstyle

I’m having some Stage 3 TEA 5.3’s posted and I need to find out how much to mill them if any. Here is what I’ve come up with, let me know if this looks good or if I should change anything.

Scenario 1

Cylinder head volume 61.37cc (un-milled)
Piston head volume .000
Gasket thickness .040
Gasket bore 3.910
Cylinder bore 3.900
Deck clearance -.008 (general number until I check mine)
Stroke 3.620
Rod length 6.125

IC ABDC 45 + 15 = 60

This gives me a static compression of 11.476 and a dynamic compression of 9.447 with a quench of .032



Scenario 2

Cylinder head volume 60.00cc (milled .011) – Assuming ~.007 = 1cc
Piston head volume .000
Gasket thickness .040
Gasket bore 3.910
Cylinder bore 3.900
Deck clearance -.008 (general number until I check mine)
Stroke 3.620
Rod length 6.125

IC ABDC 45 + 15 = 60

This gives me a static compression of 11.693 and a dynamic compression of 9.622 with a quench of .032




Of these scenarios, which one in your opinion would make more power? Scenario 1 gives me a little more room to work with regarding duration in my cam, but that doesn’t mean it would make the most power.

thanks

Beast96Z

iTrader: (21)

9.4 is very high and 9.6 is way to high. I think the target is closer to 9:1 or just below that. You may run into tuning problems and also some pinging.

jermstyle

Okay, I can change the cam and shoot for 9:1.

Should I leave the heads un-milled and bring the compression up by setting the quench at .032?

Also, is 61.37cc the size of the 5.3 head?

jermstyle

50* IC ABDC = 9.100 dynamic compression.

jermstyle

So does this look right?

Beast96Z

iTrader: (21)

Okay, it looks like a few things are off in your calculations. Some how you are coming up with 11:4:1 compression, when it should be 11:01:1 by my calculations. Second, you don't want your quench at .032, it is better suited between .035 and .040. So by what I am getting, and what I would personally do, keep everything the same except the gasket thickness. Swap that to some .045" cometics. This will net you a Static ratio of 10.88:1 and a DCR of 8.90:1 and put your quench at .037".
If you stay with .040 gaskets, you will be at 11:1 and have a DCR of 9:1:1 and a quench of .032". I little on the high side IMO.

John B

iTrader: (10)

Beast96Z nailed it unless you plan on using Octane Booster or keeping your RPMs low to avoid a potential meeting of the valves and pistons at high RPM!

My90Iroc

iTrader: (26)

How are you getting the cam variable?

H82BBad

after running the numbers again I am with beast96z

http://www.kb-silvolite.com/calc.php?action=comp

jermstyle

http://www.kb-silvolite.com/calc.php?action=comp

This is the calculator I used to come up with these numbers. I've found reference to it several times while running searches on the forum so I figured it was fairly accurate.

If this is off, would someone mind telling answering a few questions?

First of all, I would like to have my static compression right at 11:1 and the dynamic compression as high as possible with 93 octane fuel and a good tune.

If I bring my quench up to .035 and use a .043 gasket, how much would I need to mill my heads for 11:1 compression and how many degrees should the IC ABTC be on the cam for the optimal DCR?

Thanks!

Jeremy

Beast96Z

iTrader: (21)

Here is a suggestion: if you have to have 11:1, mill your heads to 60cc's. That shouldn't be more than .010". This will get you your 11:1 and still let you keep the .045" gasket which will keep your quench optimal. Your DCR will then change to 9:0:1. When I was looking at the DCR calculators, I found these 2 to be more helpful:
Use this to calculate your SCR: http://www.rosspistons.com/calculator.php
Use this one to then calculate your DCR: http://www.rbracing-rsr.com/comprAdvHD.htm Don't forget to add 15 to your ABDC and just enter 0 for boost and altitude.

jrp

iTrader: (16)

that calculator is way off in terms of DCR. if i take my IVC @ .050 and add 15* like the directions say its off by 11.5* from my duration @ .006 which is the calculation you need to be taking.

using the calculator from J-Rod and having it confirmed by others my setup comes out as folllows:

SCR: 12.03
DCR: 8.5

using your calculator it comes out at:

SCR: 12.03
DCR: 9.4

it comes out correct when i use my IVC @ .006.

Beast96Z

iTrader: (21)

JRP, are you refering to the links I posted or the ones the were using? When I used the kbsolvite one that they used, I came out way off, the one I used seems to be more realistic. I wish I new my IVC@.006". The cam card only lists .050".

Grant B

Isn't a quench of .032" suicide? Did you measure all the points of all the pistons, because some are higher than others, and the piston tops themselves aren't perfectly flat.

jrp

iTrader: (16)

i was refering to the link Jeremy posted/used.

jermstyle

I haven’t actually checked my engine 'yet' to see where the pistons are and find the high points. I used .008 as a general variable in my formula as .008 is common between most LS1’s. I will check mine when my heads show up and then buy the right gasket.

.035 is pretty close, I might just bump it to .040 for a little more clearance in the higher RPM’s. I’m sure there is an optimal quench given a few variables, I just haven’t found any info on how to calculate this because it’s almost a judgment based on engine building/tuning experience.

If anyone has a lot of this, feel free to chime in.

CamTom12

iTrader: (1)

Ok, not to break into this thread but could one of ya'll give me a quick definition of quench? I want to make sure I'm clear on all the details (I love reading discussions like these... they help me make better decisions down the road).

Thanks!

Grant B

Optimal quench is supposed to be as close as possible before the piston hits the head. Any gap reduces the "squish" effect with associate turbulenec, and can create a pocket for end-gas, which is what causes knock in the first place.

At least thats the theory...

Beast96Z

iTrader: (21)

Quench is the area between the top of your piston at TDC and the deck surface of your head. If your piston is .008 out of the hole and you have .045" thick gaskets you have a quench of .037". A good rule of thumb used by almost all builders is to get your quench between .035-.040". Go.035 for maxed applications and .040 to be on the safer side.
Jermstyle, I think you'll be fine with the .o45 gaskets. Just be sure and check your pistons, which you can do now if you have your shortblock assembled, and go from there. I think the above scenario I posted will be just about right for what you want.

jermstyle

Beast and everyone that replied, thanks for looking at my numbers and helping me out with this. The straight forward and educated help is much appreciated!

I called TEA today and asked them to mill my heads just enough to give me 60cc chambers. I’ll then go with the .045 gasket assuming my pistons are .008 out of the hole, if not I will adjust accordingly.

Was your DCR calculation based on 45* IC ABDC?

Thanks!

Jeremy