Since money is tight lately im forced to build my 406 for mixed gas use....In order to get the compression down to 10.80-1 i need to run an extra thick .080 head gasket..Is there any way other than guessing how much power will i lose from lessening the quench area?Im pretty much stuck with 8cc domes and 64 cc chambers..

like i said above cash is tight and im waiting for big brother to release my money from i dmaaged car i sold to a guy over seas..

 

You'll be more prone to detonation with a large quench. Probably the hp loss will be more due to the loss of compression ratio. Of course lower CR reduces detonation potential.

 

You'll be more prone to detonation with a large quench-OldSStroker

OldSStroker's correct !

the fastest NHRA SuperStock & Stockers engines i've seen apart ,
more than half SBC engines had piston decks very lightly hitting the heads , and the other half of SS's were not far behind

the LESS your total quench/squish clearance is , the more HP/Torque you will make as long as you don't take it too far !

if you plan on using an .080" thick headgasket to reduce CR to the point of not clattering/detonation.....you might not totally eliminate the clattering/detonation/pinging

the preferred/proper method would be to keep total deck/quench clearance around .035 and unshroud chambers around valves and polish chambers to enlarge chamber volume CC's that way to reduce CR

that way, squish/quench area effect is still great and working like its designed to....and you lower CR along with HP gain from valve unshrouding chamber polishing

in all my dyno testing, with all types of engines/compression ratios, 1 point in CR = 10 to as much as 26 HP depending on
cylinder head flow/cam timing/cross-sectional area of port

as Compression Ratio is increased , you put a sooner and harder hit on the entire induction system (also exh) , that gives you more ram/inertia at intake valve closing point

 

Guys...... Very good and very informative. I appreciate the info and your perspectives.

 

Thats what i understand..But im pretty much stuck with running the tick gasket..I plan on milling the heads and decking the block later in the year down to 0 deck and 49cc chambers..I need to get the car driving on the street for a while on pump gas..I live in an apartment now so no 55 gal drums of meth..

Thanks for the reassurance

 

We've had a few police raids on "meth labs" around here recently, but maybe that's not what you mean.

Hey, try the thick gasket and see what hpppens. You probably won't hurt the engine, and you can keep checking for detonation, and adjust timing as necessary.

Good luck and keep us all informed!

 

Man , I gotta stop calling it that..ROTHFLOLPIMP..

I should have the heads assembled next month..I talked to a buddy that runs and .080 in his mopar and has good results..Im hoping that with the duration at .050 being in the 260ish range and the decent chambers in the iron eagles will allow me to get away with 92 octance and octance boost..

Ill let you know when it hits the dyno

 

I'm starting to like MaxRaceSoftware! He's going to be a great addition
to this forum!

I ran 235 PSI of static compression with a 0.022" deck and 0.017"
comrpessed steel gasket on 92 octane.

The camshaft was a Crane Energizer 0.480"/228 degree sym. cam
and TRW domes (don't recall dome size) with 72 cc chambers.

My timing was bumped to 37 degrees advance and not one issue
with performance using a full iron block.

I think you're underestimating the octane level.

Check out my link for the details of the motor:
http://www.rudyhelds.com/Customer_Ri...Camaro_Z28.htm

(Slight changes since the last motor)

 

I was running close to 11.75 (on at least two cylinders, explain later) on 93 octane in my big block with a quench height of .044. just last week though I reduced my quench height to .036. While I had everything apart I decided to check my chamber volumes. Well the good General screwed me. starting from the front to rear of the old 1969 Oval port heads the combustion chambers would go from 110 to 115cc. So I evened them out a bit. I closed the gap to a 1.5cc range rather than a 5 cc range. So now I am at 11.5 or so, and still running 93 on a full iron block.

But I also have a little help from long rods (6.535 compared to 6.135) and larger bore coated pistons and a short 3.755 stroke, rod ratio is right around 1.75 which is a great place to be when trying to squeeze by on pump gas with a high compression engine.

Opening up the quench height is a bad bad idea, aviod large quench areas if at all possible.

 

Zero_to_69 ... Thanks !!


i use to race a 1970 Olds 442 W-30 455 NHRA F/SA
red plastic inner fenders , alum rear cover and spcl rear end,
4.66:1 factory gears ?



the Olds combustion chamber has a lot less Quench/Squish area ratio than SBC ..so Olds needs all the help you can give it in the Quench/Squish department