Supercharging and Quench

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ramcharger

ramcharger

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What effect does quench have in a supercharged engine? Is this something that's usualy not even explored as quench can't be achieved at the lower CR's needed for forced induction?

Just curious is all. :read2:
 
Well I just can't let your post go unreplied :)
I know quench is supposed to reduce knock and octane requirement at higher compression ratios, but I think with boost you'd have to run race fuel and maybe aluminum heads to get away with it. Unless you just never stepped on the gas too hard. I see a lot of those all-aluminum honda 4 bangers on craigslist for sale that have a turbo installed running like 4psi, and I'll bet they have damn good quench and squish but end up blowing up or running like crap. Then again, my advice is free and you get what you pay for :)
 
65TerrorCuda said:
Well I just can't let your post go unreplied :)
I know quench is supposed to reduce knock and octane requirement at higher compression ratios, but I think with boost you'd have to run race fuel and maybe aluminum heads to get away with it. Unless you just never stepped on the gas too hard. I see a lot of those all-aluminum honda 4 bangers on craigslist for sale that have a turbo installed running like 4psi, and I'll bet they have damn good quench and squish but end up blowing up or running like crap. Then again, my advice is free and you get what you pay for :)
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LOL, I just saw this, sorry it took so long to respond. I was originally thinking of a v-8 built with quench at a CR of 8-8.5:1 vs. a v-8 built without quench at the same comp ratio. I wondering if there would be any difference in regards to power output and octane requirements.
 
My dad just went through this with his LS-7 that he is putting a whipple charger on.

It is not as inportant to have on a supercharged motor but if it can be done it should be. They use a dished piston and if it does not need a lot out of it they will leave the quench part alone and dish the other side. You can also get a head with more CC's in it so the piston does not need so much dish in it and you can keep your quench area. My dad had his cumbustion chambers recut for more CC's so he would not need as much piston dish and could keep his quench area.

Hope this helps Ram. I am no expert for sure. This is just what info we found while doing this build. BTW it should be making around 1000HP on pump gas and 1200 on race gas.
 
Burntorange70 said:
My dad just went through this with his LS-7 that he is putting a whipple charger on.

It is not as inportant to have on a supercharged motor but if it can be done it should be. They use a dished piston and if it does not need a lot out of it they will leave the quench part alone and dish the other side. You can also get a head with more CC's in it so the piston does not need so much dish in it and you can keep your quench area. My dad had his cumbustion chambers recut for more CC's so he would not need as much piston dish and could keep his quench area.

Hope this helps Ram. I am no expert for sure. This is just what info we found while doing this build. BTW it should be making around 1000HP on pump gas and 1200 on race gas.
Click to expand...

Thanks Burntorange. I was just curious is all and what your dad is doing makes sense.
 
I have done a little research on this... General thinking is this is a non issue for blower applications.. I will tell you in a couple days though what the real world application is. I currently have a zero deck reverse dish piston set up at 9:1.. I am going to ruin my quench on purpose by throwing a thick cometic gasket ( to drop a little compression ). If current thinking is correct I'll be fine.. if not, I'll let you know !
 
I tried to tell them the same thing in another thread but I got *** raped.

Dave_n_68383S said:
I have done a little research on this... General thinking is this is a non issue for blower applications.. I will tell you in a couple days though what the real world application is. I currently have a zero deck reverse dish piston set up at 9:1.. I am going to ruin my quench on purpose by throwing a thick cometic gasket ( to drop a little compression ). If current thinking is correct I'll be fine.. if not, I'll let you know !
Click to expand...
 
As some of you know I have been exploring putting a blower on a 5.9 magnum. It is a quench headed engine and from what I have been able to gather it makes no major difference and may even hurt a little. This is going to get a little technical so bear with me.
In a normally asperated engine you want the peak cylinder pressure to happen shortly after TDC. This allows the air/fuel mixture to exert the maximum pressure on the piston and force it down onto the crank. On a forced induction engine there is more air/fuel to burn so the maximum pressure lasts longer. With this in mind it is better to ignite the fuel a little later so the maximum pressure lasts longer in the power stroke. This is why there is a huge gain in torque in a forced induction engine. Look at it this way, say your maximum pressure in a normally asperated engine is 1000 psi with the piston position 3/4 of an inch from TDC. The pressure will drop very quickly as the piston goes down the bore. Now in a forced induction engine the maximum pressure of 1000 psi is achieved with the piston down 1 1/4 inchs down the bore. In the forced induction engine the pressure is maintained for a longer period because there is more air/fuel and also the force is on the piston for a greater percentage of the power stroke due to less distance of travel. With this in mind, there is no advantage to having quench heads. This may all go out the window in something with 40 or 50 lbs of boost but I havn't looked into that. Don't use these numbers for figuring your engine. They are just numbers for showing the relation ship of where the piston would be in relationship to the head.

Jack
 
Imagine that. So I got *** raped.....I was right and got not one single "oh sorry Rob, we *** raped you for nuthin" from anybody. That figures.
 
Well my dad's motor is still not done. Have been waiting on an adaptor plate for the whipple charger. So it will not be ready for this Glamis season but should have it for next year. I know it is a chevy but I will let you know how it does. Should be interesting.
 
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