Anyone care to talk about quench?
+ Reply to Thread
Page 1 of 3 1 2 3 LastLast
Results 1 to 14 of 37

Thread:
Anyone care to talk about quench?

  1. #1
    Senior Member H20MOFO's Avatar
    Join Date
    Dec 2007
    Posts
    4,288

    Default Anyone care to talk about quench?

    According to my build sheet mines .065., that's loose right? I'm clueless here. Does boost change things, as far as quench???
    Another Hot Boat refugee

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Senior Member wagspe208's Avatar
    Join Date
    Apr 2008
    Location
    waterloo
    Posts
    2,034

    Default

    Loose? Well, not optimum but are you needing to make every last hp? I assume steel rods? Is your tuneup on the ragged edge? Aluminum rods, is what it is, need that much or piston to head issues.
    .040 would be better to achieve the "quenching effect".
    The truth....you can get your block decked .025, have .040 and never know the difference for your application.
    Wags
    Huge difference between race and performance. Race, all is max effort. Performance, safety is built in.

    Or did you mean the refreshing taste of an ice cold beer on a hot day?

  4. #3
    Senior Member H20MOFO's Avatar
    Join Date
    Dec 2007
    Posts
    4,288

    Default

    You made me spit beer. lmao So to meas quench it's the distance from the valves(while open) to the piston?????????? No racing here, but I hope to run my low compression 557 around this season,and come back next season with a couple of atmosphere adders. I'm running a dished je piston at about 8.3 to 1 fwiw.
    Last edited by H20MOFO; 02-06-2009 at 08:33 PM.
    Another Hot Boat refugee

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    Banned
    Join Date
    Aug 2008
    Posts
    742

    Default

    Piston to valve clearance is not Quench. Quench, is the area above the piston that has little to no combustable volume. (a cooler zone) Piston to valve clearance is the difference between "running and breaking". "As simple as I could say it here".

  7. #5
    Senior Member H20MOFO's Avatar
    Join Date
    Dec 2007
    Posts
    4,288

    Default

    Generally speaking does a dished piston hurt quench In my case I hope to make big #'s with 2 475bw turbos, using my 116 cc brodix heads. I'm not worried about the combo as is, it's 8.3 to 1, I probably couldn't make it ping if I wanted to. I'm wondering ........ if it changes with boost....I don't get it.lol
    Another Hot Boat refugee

  8. #6
    Senior Member Factory1's Avatar
    Join Date
    Oct 2008
    Posts
    1,134

    Default

    The ins and outs of quench could really make for a long post. You know they say a motor should be an overall plan, all parts picked to work well together to acheive the desired goal. It would be impossible to tell you whats right or wrong without knowing WAY more about what you have put together, and what its intended use is. You mentioned boost, how are you getting it, blower? 671...1471? a Paxton, turbo? Whats the compression ratio and fuel you are going to use? Typically when we talk about quench, we are refering to the area between the piston and cylinder head adjacent to the combustion chamber. Do you know if you have open chamber or closed chamber heads? That will have a dramatic effect on quench if the pistons weren't selected appropriatley. Ultimately when building an engine, and setting the quench, it is the measured distance between the piston at top dead center and the cylinder head. Example: flat top piston set at zero deck height, closed chamber cylinder head. The quench will be whatever thickness your head gasket is compressed. Wanna change the quench, change your head gasket. In a naturally aspirated motor built for performance, you want that quench area tight, has to do with neat things like flame travel, end gases and the like. I'm not into blower motors so I have no knowledge of how quench effects them. Also a big consideration like somone else stated, are you running steel or aluminum rods? It's really a big F'ing can of worms, I can see why some of the brighter guys in here don't want to get involved. You really need to post ALOT more information to get a better answere. Once again I would like to go on record and say I don't know Jack Shit. Goodluck!

  9. #7
    Senior Member Factory1's Avatar
    Join Date
    Oct 2008
    Posts
    1,134

    Default

    Dang you posted info while I was typing, no fair!!

  10. #8
    058
    058 is offline
    Senior Member
    Join Date
    Dec 2007
    Posts
    4,115

    Default

    Quote Originally Posted by H20MOFO View Post
    Generally speaking does a dished piston hurt quench In my case I hope to make big #'s with 2 475bw turbos, using my 116 cc brodix heads. I'm not worried about the combo as is, it's 8.3 to 1, I probably couldn't make it ping if I wanted to. I'm wondering ........ if it changes with boost....I don't get it.lol
    Quench is also known as squish, it is the area of the head that is flush with the overall surface of the head. It is a part of the combustion chamber and when the piston reaches TDC the area is reduced down to the smallest gap determined by the head gasket, piston and block deck height, it creates turbulence as the piston travels up the bore on the compression stroke, this turbulence is very beneficial to gasoline and can reduce the octane requirement for a given compression ratio. A dish piston with a round "dish" will reduce the quench area and can be enough of a problem that most premium piston mfgs will make a "reverse dome" piston meaning the "dish" is a mirror image of the combustion chamber shape so there is no quench lost to piston dish. In short a 9 to 1 c/r with quench will be less prone to detonation/pinging than a 8 to 1 c/r and a open chamber head with no quench. To add: Google " Sir Harry Recardo" this subject has been known for 80+ years and it was him that discovered and developed the effects of turblence in the combustion chamber of internal combustion engines, both gasoline and diesel.
    Last edited by 058; 02-06-2009 at 10:18 PM.

  11. #9
    Senior Member Factory1's Avatar
    Join Date
    Oct 2008
    Posts
    1,134

    Default

    Well yeah, a dished piston can majorly effect quench, but is it a full dish, or a reverse dome (partial dish) piston? I know nothing about proper set up of turbo motors, I think I hear my Mom calling me, I gotta go!

  12. #10
    steelcomp was here
    Join Date
    Dec 2007
    Location
    n/e TN
    Posts
    26,507

    Default

    Detonation kills. It's what we're always fighting with the internal combustion engine. Raise the compression for more A/F mix, and risk detonation. Add boost, risk detonation. Increase cylinder pressure in any fashion, risk detonation. Detonation occurs basically when temps in the combustion chamber rise to a point where they ignite part of the A/F mixture away from the actual spark, and ignite a portion of the A/F mixture that doesn't burn, but more explodes. Heat in the chamber is the main cause of this. Heat and an increase in cylinder pressure are directly related. Without going into depth, quench areas are called quench areas because they "quench" or "cool" the temps in the combustion chamber in the area of the quench, and therefore have an overall cooling effect on the combustion area. Any time you're raising cylinder pressure, quench becomes increasingly important. Quench in turbo engines is huge in allowing increased boosted levels without detonation. Quench doesn't have to occur between the flat of the piston and the head deck, either...it can occur between any two surfaces that approach each other in the chamber in close proximity, like the dome on a piston to the chamber roof. This can cause a quench effect. Quench "pads" are often strategically placed on domed pistons in 4 valve pent roof chamber designs where static compressions as high as 12:1 can be used in turbo applications, because of the effect of proper quench. Reverse dome pistons, where the dish in the piston matches as closely as possible the shape of the chamber provides greater areas of quench (and will allow higher cylinder pressures before detonation), as stated above, as compared to a conventional dished piston which gives up quench.
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

  13. #11
    Senior Member H20MOFO's Avatar
    Join Date
    Dec 2007
    Posts
    4,288

    Default

    Interesting info indeed, I find it bizzar(sp?) that an 8 to 1 deal can be more likely to ping than a 9 to 1 set up. I don't think I understand the difference between a dish and a reverse dome piston, maybe I'll see if I can find a shot of mine and see if some one can tell me what I have. The rods are steel, you guys asking has got my curiosity, I assume if I had alum. rods I'd need a little more room? I can see I need to do some more reading regarding this(quench/squish)
    Another Hot Boat refugee

  14. #12
    steelcomp was here
    Join Date
    Dec 2007
    Location
    n/e TN
    Posts
    26,507

    Default

    Quote Originally Posted by H20MOFO View Post
    Interesting info indeed, I find it bizzar(sp?) that an 8 to 1 deal can be more likely to ping than a 9 to 1 set up. I don't think I understand the difference between a dish and a reverse dome piston, maybe I'll see if I can find a shot of mine and see if some one can tell me what I have. The rods are steel, you guys asking has got my curiosity, I assume if I had alum. rods I'd need a little more room? I can see I need to do some more reading regarding this(quench/squish)
    A dished piston will have a dish in it that's just a basic concentric shape, like round or oval. A reverse dome will be a dish in the piston that more resembles the shape of the combustion chamber, much like the dome of a piston must resemble the shape of the combustion chamber, only in reverse.
    Aluminum rods need more initial (cold) clearance between the flat part of the top of the piston and the cyl head deck surface (also known as the quench area). As the aluminum rod heats up, it will grow, moving the piston closer to the head and reducing that clearance to a normal "quench". Once the aluminum rod has grown, the quench should be the same as a steel rod, some where around .040".
    HTH
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

  15. #13
    Senior Member H20MOFO's Avatar
    Join Date
    Dec 2007
    Posts
    4,288

    Default yikes

    From the way you describe them, it sounds like mine a dished(-20cc), It sounds like throwing boost at this thing the way it's set up, would be bowtie murder. I though my motor guy would have taken better care of me that that. It says here my deck height clearance is .025, couldn't he have just taken .025 off the deck height and I'd be golden? Or am I not seeing the forest for the trees here. Before I try to boost this thing I was going to have some port work(or get bigger heads) could I angle mill my heads .025 or so and cure my quench issue??
    Another Hot Boat refugee

  16. #14
    [email protected]
    Join Date
    Feb 2008
    Location
    Ohio
    Posts
    1,011

    Default

    If your deck height is .025 and you have a gasket .015 thick then you will have .040 quench.

    Tim

+ Reply to Thread
Page 1 of 3 1 2 3 LastLast

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in

Tags for this Thread

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95