806 heads anyone?!?!
Thread Starter
Teching In
Joined: Aug 2021
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From: Bakersfield
806 heads anyone?!?! Ok so I want to build some 806s. I made this account cuz I am tired of looking up stuff for these heads and everyone always just says "theYRe TrAsH, jUst BuY 241s, pEriMItEr bOLt ValvE covER suCKs" bla bla bla you get the point. So I'm gonna build my ls1 to be as efficient and cheap as I can while still being daily driveable and yes with 806 heads!!!! I've only been a machinist for just over a year so of course I don't know it all so I appreciate any help along the way so anyone wanting to build 806 heads this is your thread. So my build is gonna be stock 5.7 bottom end, low lift cam maybe tsp stage 3 with 114 lsa, stock lt1 springs, and I keep seeing 806 cc volume is 66 cc so I plan on surfacing as much as possible or until I hit 11:1 compression. I will check the cc of these every .005 or .010 to see where I will be and post my findings here.
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Cost vs Brain Much of my life was spent to find best cost/performance.
Then I too was "bent over" here because my requirement for an Air Boat T/T DD engine was told but not understood by MOST here.
So I state, small intake port, low cost, chamber quench design (?) could be YOUR best requirement ?
So I ask, more info ?
Example, larger valves will fit fine.
Then I too was "bent over" here because my requirement for an Air Boat T/T DD engine was told but not understood by MOST here.
So I state, small intake port, low cost, chamber quench design (?) could be YOUR best requirement ?
So I ask, more info ?
Example, larger valves will fit fine.
Thread Starter
Teching In
Joined: Aug 2021
Posts: 11
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From: Bakersfield
I've saw on another post that apparently 243 valves are a few thou longer but still same diameter but I'll have to check that next time we get a set of 243s in, I've seen people run ls3 valves on 799s but when we tore them down the valve was barley on the seat, Id like to find a trash head and cut it up to see if there's enough material to put bigger seats then maybe run ls3 valves with piece of mind that seats won't drop. So the main difference between 243 and 806 that I've seen is a bit of flow, compression, and valve cover bolt location. Which I don't see why we're told to spend +$500 on a set of heads instead of $50 on a port/polish kit $50-$100 on a custom surface job and some good valve cover gaskets or add gasket maker right?
According to some Youtube heros.. The 706's are where it's at as far as highest horsepower producing in as-cast form GM LS heads. They are center bolt. Also, as many have figured out.. The chamber volume for the LS heads are always listed as LESS THAN what they actually are. I would do a CC test to see where you are at right now. I'll bet they are more than the 66.9 CC they are listed as all across the internet. I'd bet they are closer to 69CC's. Your machinist can help you mill them to get them to where you want/need them to be.
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One artest @ LS-1 Tech I ADMIRE one who is capable of machining the "806" head and making it an Art Form.
My method would be the install a 1.6" Exhaust with a Radius Face, very proud.
Then I would "sink" the Intake.
Porting, radius valve pockets, etc.
My method would be the install a 1.6" Exhaust with a Radius Face, very proud.
Then I would "sink" the Intake.
Porting, radius valve pockets, etc.
Why would you ever want to sink the intake valve? Educate me…
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Verdad Gallardo TECH Enthusiast
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Intake Valve/Seat Design Ok, think about the angles of a correct Venturi Design.
There must be an exit angle used to recover pressure without stall.
Thus "sink" the intake to recover flow speed, NO Tumble.
The exhaust is opposite, the "entry angle" with a LARGE radius on the valve face will act as a venturi if "proud".
THIS design will STOP "crossover" fuel from entering the exhaust port.
Low lift flow will be great, very important for a shorter required cam duration.
The best effect with this concept is that the P/V will be greater, more Valve Drop distance.
Now with respect to the Piston Crown, the Valve Knotch can be LESS, a greater distance from the top ring.
There must be an exit angle used to recover pressure without stall.
Thus "sink" the intake to recover flow speed, NO Tumble.
The exhaust is opposite, the "entry angle" with a LARGE radius on the valve face will act as a venturi if "proud".
THIS design will STOP "crossover" fuel from entering the exhaust port.
Low lift flow will be great, very important for a shorter required cam duration.
The best effect with this concept is that the P/V will be greater, more Valve Drop distance.
Now with respect to the Piston Crown, the Valve Knotch can be LESS, a greater distance from the top ring.
Thread Starter
Teching In
Joined: Aug 2021
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From: Bakersfield
This makes sense tho a buddy of mine built an lsx and his heads were some good brodix heads but when we checked the valve length it was way off any ls valve we had seen but when we checked stem height it was still average ls 2" we wondered why but this was it to help flow and create a venturi I assume
Thread Starter
Teching In
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From: Bakersfield
I'd like to do 5 angle valve job on intake and radius exhaust but that is for stage 2 of my build lol who knows when I'll have enough money to do that but for now simple cheap machining to beat 243s
Thread Starter
Teching In
Joined: Aug 2021
Posts: 11
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From: Bakersfield
Ok, think about the angles of a correct Venturi Design.
There must be an exit angle used to recover pressure without stall.
Thus "sink" the intake to recover flow speed, NO Tumble.
The exhaust is opposite, the "entry angle" with a LARGE radius on the valve face will act as a venturi if "proud".
THIS design will STOP "crossover" fuel from entering the exhaust port.
Low lift flow will be great, very important for a shorter required cam duration.
The best effect with this concept is that the P/V will be greater, more Valve Drop distance.
Now with respect to the Piston Crown, the Valve Knotch can be LESS, a greater distance from the top ring.
There must be an exit angle used to recover pressure without stall.
Thus "sink" the intake to recover flow speed, NO Tumble.
The exhaust is opposite, the "entry angle" with a LARGE radius on the valve face will act as a venturi if "proud".
THIS design will STOP "crossover" fuel from entering the exhaust port.
Low lift flow will be great, very important for a shorter required cam duration.
The best effect with this concept is that the P/V will be greater, more Valve Drop distance.
Now with respect to the Piston Crown, the Valve Knotch can be LESS, a greater distance from the top ring.
Ok, think about the angles of a correct Venturi Design.
There must be an exit angle used to recover pressure without stall.
Thus "sink" the intake to recover flow speed, NO Tumble.
The exhaust is opposite, the "entry angle" with a LARGE radius on the valve face will act as a venturi if "proud".
THIS design will STOP "crossover" fuel from entering the exhaust port.
Low lift flow will be great, very important for a shorter required cam duration.
The best effect with this concept is that the P/V will be greater, more Valve Drop distance.
Now with respect to the Piston Crown, the Valve Knotch can be LESS, a greater distance from the top ring.
There must be an exit angle used to recover pressure without stall.
Thus "sink" the intake to recover flow speed, NO Tumble.
The exhaust is opposite, the "entry angle" with a LARGE radius on the valve face will act as a venturi if "proud".
THIS design will STOP "crossover" fuel from entering the exhaust port.
Low lift flow will be great, very important for a shorter required cam duration.
The best effect with this concept is that the P/V will be greater, more Valve Drop distance.
Now with respect to the Piston Crown, the Valve Knotch can be LESS, a greater distance from the top ring.
TECH Enthusiast
Joined: Aug 2021
Posts: 507
Likes: 190
Absultue Case = N/A I AGREE, most here are capable of asking a question.
Most here do not state the application.
No case is absolute.
YES, I offer advice, taught by John Drake, Carl Wegner, Mike Costin, etc.
Warren Brownfield taught me about air flow, he AGREED with me, TOO large a port could "stall" flow.
The ease of predicting the behavior of an Electron or a Quark is easy
Most here do not state the application.
No case is absolute.
YES, I offer advice, taught by John Drake, Carl Wegner, Mike Costin, etc.
Warren Brownfield taught me about air flow, he AGREED with me, TOO large a port could "stall" flow.
The ease of predicting the behavior of an Electron or a Quark is easy
TECH Senior Member
Joined: Jun 2016
Posts: 22,291
Likes: 3,616
From: Central Cal.
I've saw on another post that apparently 243 valves are a few thou longer but still same diameter but I'll have to check that next time we get a set of 243s in, I've seen people run ls3 valves on 799s but when we tore them down the valve was barley on the seat, Id like to find a trash head and cut it up to see if there's enough material to put bigger seats then maybe run ls3 valves with piece of mind that seats won't drop. So the main difference between 243 and 806 that I've seen is a bit of flow, compression, and valve cover bolt location. Which I don't see why we're told to spend +$500 on a set of heads instead of $50 on a port/polish kit $50-$100 on a custom surface job and some good valve cover gaskets or add gasket maker right?
The ports in the 243/799 castings are much better than the other cathedral port castings. Most of the difference is in the short turn, where the floor is taller and the radius is more ideal for high airspeeds.
[/QUOTE]The ports in the 243/799 castings are much better than the other cathedral port castings. Most of the difference is in the short turn, where the floor is taller and the radius is more ideal for high airspeeds.[/QUOTE]
and yet dyno tests readily available comparing back-to-back head testing on the exact same engine with no other changes show the 706's make MORE HP and MORE TORQUE in the average daily driver RPM ranges than both the 799 and 243 heads. Even though flow benches show that the 799/243's outflow the 706's number wise, the dyno shows that the 706's (below 6000 RPM I think??) make more HP and more torque..
I've sold off the 243's I have and am about to remove the 799's I have on my 6.2 in favor of a set of ported and polished 706's.
and yet dyno tests readily available comparing back-to-back head testing on the exact same engine with no other changes show the 706's make MORE HP and MORE TORQUE in the average daily driver RPM ranges than both the 799 and 243 heads. Even though flow benches show that the 799/243's outflow the 706's number wise, the dyno shows that the 706's (below 6000 RPM I think??) make more HP and more torque..
I've sold off the 243's I have and am about to remove the 799's I have on my 6.2 in favor of a set of ported and polished 706's.
Last edited by Kawabuggy; Aug 24, 2021 at 12:03 PM.