706 LS heads - how'd I do?

[KnightEngines]

Never ported a set of these before, never even seen a set before!

Did these for an R&D hack developing a new ITB intake for cathedral port LS stuff, a rectangle port setup is in the works as well.
My job was just to produce a decent set of heads for testing, owner can port, but lacks free time to do so.

I cut seats for the new 2.02/1.57" valves & hacked at the ports with a view to make as much gain as possible without spending too much time, they are not pretty.

Some input on how I've done compared to others would be good, I got no baseline to compare too!
I was pretty impressed by how easily they flowed some pretty good numbers with not a lot of work, only real drama was keeping them stable at high lift, but even that was easier than larger valve cathedral port heads.

Intake flow
20191011_140210 by tony knight, on Flickr

Exhaust flow (no pipe)
20191014_153047 by tony knight, on Flickr

706 ls by tony knight, on Flickr

706 ls by tony knight, on Flickr

706 ls by tony knight, on Flickr

706 ls by tony knight, on Flickr

706 ls by tony knight, on Flickr

[Carnut1]

Resized_20190814_183752_9329.jpeg

LS cathedral ports are an interesting design. Seems to me most guys just make them big and they flow well. I am working on a cathedral port aftermarket head and Holley manifold combo. 2.02" 1.6" 220cc runner and a little over 300 cfm @ .7" through the carb all bolted to the bench. The intake works very well after with nearly identical flows from each runner.

[CGT]

I think the 706 and 862 castings have a lot of potential within the OE cathedral castings, yet they get passed over frequently in favor of 243 and 799. What are they going on? How big is the intake throat?

[Zmechanic]

Hey Tony, not sure what application you have these pegged for, but I've always seen some back and forth on the swirl ramp on whether to take it out, leave it, shrink it, etc. For a WOT or race application, I imagine taking it out is the right move. For a street motor I'm not sure, but potentially depending on displacement and expected port velocities. What are your thoughts?

Also, if those are used and have the Castech casting mark on them (looks like the battery symbol on many electronics) on the intake port in the rocker area, I'd pressure test them if they haven't been done already. They are known for cracking around the inner head bolt bosses which lets them bleed coolant into the engine when the coolant system pressurizes.

[CGT]

Also, if those are used and have the Castech casting mark on them (looks like the battery symbol on many electronics) on the intake port in the rocker area, I'd pressure test them if they haven't been done already. They are known for cracking around the inner head bolt bosses which lets them bleed coolant into the engine when the coolant system pressurizes.

That was only the 862 cast I believe. But they do make a mess when they crack.

[KnightEngines]

Hey Tony, not sure what application you have these pegged for, but I've always seen some back and forth on the swirl ramp on whether to take it out, leave it, shrink it, etc. For a WOT or race application, I imagine taking it out is the right move. For a street motor I'm not sure, but potentially depending on displacement and expected port velocities. What are your thoughts?

Also, if those are used and have the Castech casting mark on them (looks like the battery symbol on many electronics) on the intake port in the rocker area, I'd pressure test them if they haven't been done already. They are known for cracking around the inner head bolt bosses which lets them bleed coolant into the engine when the coolant system pressurizes.

No cracks in these ones.
The motor is a stock freshened up 5.7 ls1, cam in the 230's, intake is the new RHD ITB, the motor is a development mule for the intake.
I've always taken the ramp out, but most of the LS stuff I do is competition.
Intake looks to be the goods for a basic street engine, I'll put some pics up shortly.

[KnightEngines]

I think the 706 and 862 castings have a lot of potential within the OE cathedral castings, yet they get passed over frequently in favor of 243 and 799. What are they going on? How big is the intake throat?

Intake throat is at 88% now.
I agree, these are good heads, smaller bowls give more room to set things where you want, not where the existing casting forces you to, but there is more work in them than starting with larger valve heads.
Ports are near stock size, runners just squared up & cleaned up.

[randy331]

I did a 408 cube ls using a cathedral port head. It was the 243 casting, but I don't think there is a big difference in potential. It made good power for a pump gas street engine.

Had 10.7/1 comp, 243/258/110 comp cam with .625" ish lift. sv intake, 243 heads ported reasonably well with 2.02" 1.56" valves 50* seats, whitener 4150 carb. Pump gas pulls were the best on tq vs av gas but same hp.

It made 590 Lbs TQ and 625 HP. it came in the start of the pull at 4000 rpm making 575 LBs. I think they like the ethanol in the pump gas.

Tony will you be dynoing this one ?

Randy

[KnightEngines]

I won't be, motor is located about 1500 miles away!
It will be chassis dyno'd tho.

[jed]

Tony since most of the work was in the bowls and valve job how did you do the bowls and angles on the valve job.

[KnightEngines]

Just 35/45/65/75/80 with 1mm seat & 88% throat.
Sunk about. 030".
Bowl is really just cleaned up, short turn is laid back into the valve job & the peak moved upstream.
Port is a little wider above the turn & corner radii reduced.
Swirl thingy removed, rocker bolt boss removed & walls squared up.
Exhaust is 35/45/radius, 88% throat as well, bowl cleaned up, short turn laid back & widened a tad, roof raised a little at port exit but it's not much bigger than stock.

[S10LS2]

Just 35/45/65/75/80 with 1mm seat & 88% throat.
Sunk about. 030".
Bowl is really just cleaned up, short turn is laid back into the valve job & the peak moved upstream.
Port is a little wider above the turn & corner radii reduced.
Swirl thingy removed, rocker bolt boss removed & walls squared up.
Exhaust is 35/45/radius, 88% throat as well, bowl cleaned up, short turn laid back & widened a tad, roof raised a little at port exit but it's not much bigger than stock.

Not sure if I missed it but did not see it stated.. But do these have the smaller 1.890 intake valves still in them or did you swap out valves? Very good flow numbers if it is still stock valve.

[KnightEngines]

Nah, they have 2.02/1.57 valves

[tt 383]

Back cut angle on the intake? Someone posted up on a different forum results from different back cut angles same valve/vj/port is the only reason I ask. Those little details sure do paint a picture...

As always thanks for posting results and specs!

[brentry]

Mine flow about the same. Mine just flow more earlier.
My seat % bigger. Here is a pic of a stock 243 and 862