CAT3

iTrader: (9)

Well, I finally made the plunge and ordered a APE 347ci a couple weeks ago.
Diamond coated pistons 2cc reliefs @ 11.1:1 58cc heads, Callies/Prostar Rods for rotation side, 0.010 out the hole. I am looking at Cometic 0.040" compressed gaskets, which leave me at 0.030" quench height. On stock rods and higher rpm (7000+) I would never think of it. But, with this combo, I am thinking it will be optimal, as the rods wont grow like stockers, and if it see's more than 7k rpms, it will only be at the drags when the block will be warm and have time to expand a little giving a little more clearance. Whats you thoughts guys?
More details?
Nitrous use, yes around 200-250 shots.
Cam ground by EDC, Morel lifters, Cloyes Hex-Adjust Timing Set, TR Pushrods, APE Ported/coated oil pump. For now I have PP 5.3L Gold Spring 2.02/1.55 heads milled 0.010", but will be swapping out for 225 AFRs later this summer, as well will swap out current JetHot LTs and TDs for Kooks 1 7/8 LTs with new 3" TDs.
Stall (most likely Fuddle Racing) and gears (going to a JB Fabbed 9") pending recommendation from Ed to match the cam and vehicle profile.

Other than this quench issue, I have to wait to measure the pushrods, thinking I will end up ordering some custom length, looking at the milled heads/gaskets thickenss/cam base circle.

Thanks

Charlie

SStrokerAce

iTrader: (2)

Well the expansion rate of the rods is the same.... the stock PM rods and the Callies rods are both steel so they will expand at the same rate due to temp. The rods might stretch (very minimally) due to inertial forces but the lower mass piston and pin will help that.

The good thing is the block will grow more than a iron block as it gets up to temp.

The only thing you are leaving out here is how the alloy of the piston and the piston to wall clearance will effect the piston rock in the bore. A higher silicon allow piston will expand less and if you have a ring pack that is spaced out you will have less piston rock in the bore and therefore you can run a tighter quench.

Overall the sub 7,000rpm and the rest of the combo assuming you have a good PTW and a 4032 allow piston the .030 should not be much of a problem. You could always get a .045" Cometic gasket made and be at .035" quench and be safe there. The only sure way to know is test it out yank the head and see if it's touching... With ARP bolts/studs on the heads and Cometic gaskets all that does is take time not money.

Bret

CAT3

iTrader: (9)

Bret,

Thanks. Question on that though. The stock rod is powdered metal compared to a billet steel composition, you think they would still expand the same? I know its hard to tell unless your a metallurgist (should ask my little brother), or machinist thats worked on these two types often...I have not had a lot of technical data collecting, but thought the Callies would expand less.
Good point on the ring spacing, most time I get stuck on thinking of smaller bore = less canting, but true enough the tighter PTW + wider Ring Spacing = less rocking too.

Charlie

SStrokerAce

iTrader: (2)

The one thing about PM is that the denisty of the metal is not as good due to the fact that the PM process needs a bonding agent that acts as a filler that effects the density of the rods.

Does that mean that since they are less dense they will expand more or less.... They are still setup in a matrix of some sort so the expansion of each particle is still the same and still displacing the same amount as temp rises.

I'll ask my father about this one since he's got the best guess on this of anyone I know. 40 years of being a ME will do that for you.

Bret

CAT3

iTrader: (9)

Appreciate that info Bret, thanks.

P Mack

iTrader: (6)

FWIW Tony Mamo recommended .035" to me but said people have gone lower with no problems. Chris @ AP said no lower than .040" for safety.

slow3hoe2

iTrader: (3)

my opinion is....how much performance are ya gonna gain at .030 vs .035? i would stick with what gives you piece of mind. What is it that you are trying to gain by making the quench tighter?

z-ya

iTrader: (1)

I like .030.

PREDATOR-Z

.035>.040 should be your range IMO. The pressures with a 250 shot Nitrous augment at a mindbogling rate and are done so at an extreme rate Vs exponential supercharging for exemple.
Leave yourself some room for the "unexpected" as one of my friends would say.
As mentionned above, the gain from a .030 VS .035 or so are minimal < 5rwhp, I would think.

slow3hoe2

iTrader: (3)

my question is where does this gain come from? just more compression? why not design the piston so you get the compression you want at .035 or .040?

from reading about quench area in the past...it is said that the most efficient quench area is around .040. so i guess if u start out with .030 and once the engine is heated up and all the materials expand and such...if you end up with .040 i guess ur in. I dont know the exact expansion rates of an ls1 engine so maybe i should just shut up....but this isnt something i would guess at. Ive had engines that still tap the head even at .040

SStrokerAce

iTrader: (2)

Charlie,

To quote what he sent me:

"The coefficient of linerar expansion (CofE) for steel (about 6.4 x 10^-6 in. per inch of length per *F) varies 1-2% due to composition, method of fabrication and hardness. Cast iron has a coefficient about 4-6% more than steel (6.67x 10^-6). In other words, there's not much difference. (10^-6 is one-millionth)

For example, for a 6 inch center-to-center rod heating from 70 *F to 300*F which is probably higher than most of us run our oil temp, a steel rod will grow (230 x 6.0 x 6.4*10^-6) or about .0088 inches. If it were cast iron, it would be about .0092 or less than 1/2 thousandth more. I wouldn't adjust my quench height for forged, cast or PM rods.

Titanium has a CofE about 4.8 per *F, or 75% of steel, if you are thinking of modifying an LS7.

Pure Aluminum has a CofE about 13.9, so a 1.25 compression height piston should grow about .004 at 300*F. The top of the piston gets hotter, so give it another .001 or .002 at max power, unless you are spraying oil onto the bottom of the piston crown. Different alloys will expand a little less. 4032 CofE is about 10.8 or 78% of pure aluminum. "

So for example.....

The block expands .01799" with a increase from 70* to 210* so you quench will increase that much. (9.250" deck height * 13.9*10^-6 CofE * 140* of temp increase)

Now the parts in the motor the crank and rod both expand at the same rate.
(1/2 stroke 1.811 + 6.125" rod) = 7.936 total length

So the crank and rods will increase .01014" (200* temp increase)

The 1.315" CH piston will increase about .003124"

So all in all your Quench will increase about .0047"

So a .030" Quench will at worst cast be running at .035" when the motor is hot, so don't beat on it when it's cold.

Hope that helps.

Bret

z-ya

iTrader: (1)

Remember quench is not just for horsepower but also for detonation resistance and a wider tuning latitude.Kinda handy when spraying the house down.

Ben R

Quench for a steel rod is generally bewteen .035 and .045.
Quench for an aluminum rod is generally between .055 and .065

P Mack

iTrader: (6)

How about this. Assuming you had no rod stretch or piston rock so you could run down to .001", would there be a point where you would lose power with smaller quench? I know it's hypothetical but i'm wondering if there's a point of diminishing returns, kind of like how there is with compression.

SStrokerAce

iTrader: (2)

The point of dimishing returns is when the piston starts hitting the bottom of the head.... Detonation is hard on piston pins but this is even worse. Quench is a great thing because it forces the air/fuel in the chamber into a tighter area so the burn happens faster. It also keeps detonation at bay so you can run a higher compression ratio on the same octane gas, but only slightly.

The rules of quench all have to be changed when it comes to rod and block material..... Block/Rod combos can grow and shrink the quench while the motor is running. The effective quench is what is really important not the quench at 70* when you assemble the motor.

Bret

Viper

iTrader: (6)

Brett

My pistons are .007 out so I bought a .045 gasket to get quench at .038

Is this still correct thinking , or how do you measure effective quench?

BTW, I haven't assembled yet.

Thanks

SStrokerAce

iTrader: (2)

See post #11 here

Roughly the quench will grow .005" on a Al block LS1 347 when the motor is hot. You will have a effective quench around .042

Bret

Viper

iTrader: (6)

This is great stuff. Last October there were threads on this and no one mentioned effective quench.

Thanks again

SStrokerAce

iTrader: (2)

Nobody thinks about it, that's mostly why.

Same reasons a Al block uses tighter clearances. I think Keith at W2W mentioned he likes main clearances in the .0011-.0016 range where a SBC is going to scream at you with oil pressure if the clearances are even close to the high end of that.

Bret

DavidNJ

Ok, there is more to than material. There is cross sectional area. The H-beam rod may have significantly more cross sectional area and therefore stretch less under load. The load from slowing down that piston. The LSx pistons are pretty light, so not much is probably gained there. However the aftermarket piston may use a lighter, smaller pin and lighter rings.

Nice thread guys!