Interesting engine theory read!
Thread Starter
|
Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
Interesting engine theory read!
I ran across this link while looking around the other forums of the board. I thought it might be informative for those relatively new to the FE forum that dont understand quench and dynamic compression just yet.
Here's the link: http://www.popularhotroddingweb.com/tech/0311_phr_power_squeeze/
I found one paragraph particularly informative, as I've been preaching this for quite some time now:
A cool charge may be the first step toward utilizing a higher CR, but what happens in the combustion chamber can make or break any such efforts. A prime factor here is never to loose sight of the fact that the faster the charge can be burned the higher the compression the cylinder will stand. Chamber cavities between the piston and the cylinder head between about .060-inch - .120-inch appear most likely to be the site of detonation. Speeding up combustion mixture motion/agitation is vital. This means maximizing the quench action. On a small-block Chevy with a stock block height, a stock compression height piston is typically .025-inch down the bore. With a .040-inch gasket this makes the static quench clearance .065-inch, which is way too wide. By cutting the quench clearance the burn rate and quality improve to the point where the motor gains compression and is less likely to detonate even at the higher ratio involved.
This applies to FE's like this:
With the typical 390 build, with 360 pistons, the pistons are about .012" down the hole at TDC, as measured in my 390 using L2291F30 pistons. Use a Fel-Pro .041" head gasket, and you have .053" quench space, real close to the .060" to .120" he sites above. Use a .020" steel shim head gasket, you drop it to .032", much better. By looking at the part I marked in bold, you actually have LESS of a chance of detonation with the thinner gasket and higher compression!
Now look at the 360 motor. .104" deck clearance at TDC. This is why we convert to 390's.
Read the whole article and think about how this applies to FE's. I think you'll find it interesting.
Here's the link: http://www.popularhotroddingweb.com/tech/0311_phr_power_squeeze/
I found one paragraph particularly informative, as I've been preaching this for quite some time now:
A cool charge may be the first step toward utilizing a higher CR, but what happens in the combustion chamber can make or break any such efforts. A prime factor here is never to loose sight of the fact that the faster the charge can be burned the higher the compression the cylinder will stand. Chamber cavities between the piston and the cylinder head between about .060-inch - .120-inch appear most likely to be the site of detonation. Speeding up combustion mixture motion/agitation is vital. This means maximizing the quench action. On a small-block Chevy with a stock block height, a stock compression height piston is typically .025-inch down the bore. With a .040-inch gasket this makes the static quench clearance .065-inch, which is way too wide. By cutting the quench clearance the burn rate and quality improve to the point where the motor gains compression and is less likely to detonate even at the higher ratio involved.
This applies to FE's like this:
With the typical 390 build, with 360 pistons, the pistons are about .012" down the hole at TDC, as measured in my 390 using L2291F30 pistons. Use a Fel-Pro .041" head gasket, and you have .053" quench space, real close to the .060" to .120" he sites above. Use a .020" steel shim head gasket, you drop it to .032", much better. By looking at the part I marked in bold, you actually have LESS of a chance of detonation with the thinner gasket and higher compression!
Now look at the 360 motor. .104" deck clearance at TDC. This is why we convert to 390's.
Read the whole article and think about how this applies to FE's. I think you'll find it interesting.
Thread Starter
|
Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
It looks like we can get away with tighter quench than I had previously thought. In an FE with stronger rods than the SBC, spinning slower, we could probably go even less than the .025" he's using, right?
The point that I was trying to shed light on, was that when everything else is held constant, tighter quench will more than compensate for the increase in compression it causes.
The point that I was trying to shed light on, was that when everything else is held constant, tighter quench will more than compensate for the increase in compression it causes.
Postmaster
Joined: Jul 2003
Posts: 3,934
Likes: 0
From: iowa
Originally Posted by rusty70f100
It looks like we can get away with tighter quench than I had previously thought. In an FE with stronger rods than the SBC, spinning slower, we could probably go even less than the .025" he's using, right?
.
.
How do those hyperpeutics compare to forged pistons as for exspansion?
Thread Starter
|
Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
Forged pistons would expand much more. Hypereutectic pistons fit real tight in the bore. I'd limit it to .030" with forged pistons. At .020" with forged pistons, on a cold morning one good rev could cause damage.
Trending Topics
FE "Freakin Expensive"
Joined: Dec 2003
Posts: 6,461
Likes: 4
From: Smith Mountain Lake, VA
Thats why I'am building the 433 with a zero deck and Mr.gaskets .032" Gaskets,and I think with just over 10 to 1 cr, I'll be just fine with the quench and the anti detonation groves in the Probe forged pistons on pump gas!!
Now I'am back to looking for new Heads sometime after Christmas!! I got an offer on the C4's Sunday afternoon I just couldnt refuse!! So now back to the drawing board!! LOL.. Awww Geez!!!!
Russ
Now I'am back to looking for new Heads sometime after Christmas!! I got an offer on the C4's Sunday afternoon I just couldnt refuse!! So now back to the drawing board!! LOL.. Awww Geez!!!!
Russ
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
FE "Freakin Expensive"
Joined: Dec 2003
Posts: 6,461
Likes: 4
From: Smith Mountain Lake, VA
Yeah Matt, almost predictable Huh!! LMAO!!
And Carl....I tell you I had to think Long and hard about selling them..They were some of the nicest Iron Heads I have seen...But with that said....the guy who bought them..kept making the deal sweeter and sweeter....and for what I had in them...I really would have been stupid not taking his money!!
And yes your right Aluminum Heads are in the 433's future! Which one's yet? I dont know..
I sure like the BT's..and they flow great ported..what I dont like about them is using special Roller rockers from Doug....PumpBuilder...they are pricey!!
I also Like the Dove Canadian Head...But I have also read about passed Purosity problems? So I'am still up in the Air....And I wouldnt be able to swing any until this summer anyway..We Just spent $2500 to send the wife out to SoCal for her Dads Funeral... So Back in the Poor house I am!! LOL
Russ
And Carl....I tell you I had to think Long and hard about selling them..They were some of the nicest Iron Heads I have seen...But with that said....the guy who bought them..kept making the deal sweeter and sweeter....and for what I had in them...I really would have been stupid not taking his money!!
And yes your right Aluminum Heads are in the 433's future! Which one's yet? I dont know..
I sure like the BT's..and they flow great ported..what I dont like about them is using special Roller rockers from Doug....PumpBuilder...they are pricey!!
I also Like the Dove Canadian Head...But I have also read about passed Purosity problems? So I'am still up in the Air....And I wouldnt be able to swing any until this summer anyway..We Just spent $2500 to send the wife out to SoCal for her Dads Funeral... So Back in the Poor house I am!! LOL
Russ
!["Beemer Nut"'s Avatar](data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 50 50'><circle class='avatar-circle-default' fill='%23bc5285' cx='25px' cy='25px' r='20px'></circle><text class='avatar-text-default' x='49%' y='53%' fill='white' text-anchor='middle' alignment-baseline='middle'>"</text></svg>)
Post Fiend
Joined: Dec 2003
Posts: 6,658
Likes: 4
From: "Islander"
Sorry to hear about the passing of a family member, treat the wife with extra love. The pain lasts a long time, my dad's been gone for three years and he still tells me what i'm doing wrong when running the lathe. Take care as a motor can wait until you get the "perfect build".
.....=o&o>.....
.....=o&o>.....
New User
Joined: Aug 2005
Posts: 23
Likes: 0
i aleays shoot for around .040 not maximum but still safe and seems to work very well. trouble is most factory engines tried to be close to that number but a rebuild and thicker felpros always add alot to the quench distance. My engine ran great i repaced the heads and new gaskets and now she pings like crazy
not an uncommon scenario. best bet is milling the heads to compensate for the extra thick head gaskets if that is what you are going to use
not an uncommon scenario. best bet is milling the heads to compensate for the extra thick head gaskets if that is what you are going to use
FE "Freakin Expensive"
Joined: Dec 2003
Posts: 6,461
Likes: 4
From: Smith Mountain Lake, VA
Thanks Carl for the kind words...Yeah, its going to take some extra attention..to help her pull thru..(Daddys Girl) But his new wife took all the money to take care of her Daughters..and thats written in stone? So Back to Poor house we go!! LOL..
Russ
Russ