Guys,

I'm trying to get an idea of the differences between sponsors & their Stg. II LS6 heads. Does anybody have flow #'s for MTI, ARE, GTP? If you do, would you mind posting flow #'s? I'd be very grateful! Thanks!!

--JF

 

Well,

I found #'s for ARE & LPE and I've seen a graph of MTI's, but the graph is a bit hard to make out exactly because of the increments.

Anyone w/ MTI's LS6 heads wanna' post #'s? Please?? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> Thanks!!

 

I've heard from a friend with them that he got 317cfm from LS6 MTI Stage II's

 

Bret,

That's 317cfm at .600?

--JF

 

At the begining porting of my 2002 LS6 heads they were flowing 307 cfm at .550 lift with stock 200 01 valves.(Compared to 276 cfm not ported)I have not heard the new flow #'s with the 2.02 valves yet,but I will post them. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

The best way to confirm flow #s are to flow the heads before and after by the same porter and machine! Flow #s will change if they were flowed in different flow machines. Also, most stock flow #s are not done by the porter or there machine, but done on other machines by someone else, and they assume they are the same! If flow benches differ in there output, then how can a person know what his heads gained from the stock!

IMO, all sponsors or porters must flow there heads before they port them, and then flow them again after they port them! By doing that we will see what is the gain they have made after porting!

This is just my .02

 

Well,

I was just looking for ballpark figures. I fully realize that there will be differences between flow benches etc...

307 at .550 is really good for stock valves. I'm interested in your #'s Slowhawk after you get the bigger valves in there.

--JF

 

BTW,

Slowhawk, who's porting your heads?

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by JF WS6:
<strong> Bret,

That's 317cfm at .600?

--JF </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I think so.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by JF WS6:
<strong> BTW,

Slowhawk, who's porting your heads? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">LS1derfull is doing the work.He has the superflow flowbench.So I have back to back flow data.The last set of LS1 heads he did for a friend of mine flowed 297cfm at .550 lift with 01 LS1 heads and 01 2.00 valves with I think 217cc runners.This car has dyno'd 400+ with a TR 224 cam.I should be getting some hard flow #'s on the LS6 heads by next weekend.We are shooting for 310-320cfm at .550 lift with under 218cc chambers.We'll see <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

You got to love hi lift numbers. they sure do sound great.
But IMO I care way more about the midlift numbers.Where is your cam at longer? .500? or .300?
Thats the beauty of ls-6 heads they have killer midlift numbers.I have seen them flow 227cfm @300 and 277cfm@400.So if our intake kills some of the top end flow ,say it limits it 280 cfm(granted I know it is not linear.)
and you have 2 sets of heads
Head A: flows 300 cfm@.550 lift with the affore mentioned mid lift numbers.
Head B: flows 320 cfm@.600 lift
300@.500 255@.400 and 210@.300

Which head would you rather have?
What if head A port stalls on the bench at .575 lift losing 30 cfm@.600
Everyone preaches area under the curve in HP numbers but most neglect this in flow numbers. Even with the port stall Head A will make more power than head B with a .600 lift cam. because of the area under the curve. Also head A wont port stall on the car as it will on the bench because of intake being a restriction.
To support this I point to all the cam only cars with .560 lift + making killer power and et but stock heads port stalL AROUND .525

Sorry so long I am Not trying to write a paper,I am just trying to stress the importantence of mid lift number and stating where I think the most gains are coming from when using a ls-6 head over and ls-1 head.
My heads Flow 295@.500 and 297@.525 then they are done. I am getting ready to do another cam soon and we will see if my theory is correct.

 

I agree with mid lift #'s.That's why I will not post higher than .550 lift #'s.But there is a problem with a port that stalls at .525 on a cam that lifts to .561.The Heads I have on my car stall at around .520 and this does hurt the power.
We are also playing with the exhaust.By just adding 1.60 valves flow went up 10 cfm across the board.I really think more power is in the exhaust that porters have not found.

 

H82Bad has a point, flow is reduced with intake bolted to head, and reduced flow does affect port stall lift range.Mid lift flow is very important for power, especially when cam size is conservative, but area around peak lift flow is most critical for max power because this is where highest demand on port is.When piston is at max acceleration away from TDC you either have enough flow to add rpm(HP) or you dont.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by JF WS6:
<strong> Slowhawk,

320cfm at .550 would be crazy!... If you guys get anywhere near that I'd like to see your low lift #'s as well - 'cause usually there's a trade off involved with getting really good high lift #'s.

Let me know how it turns out if you get the chance.

--JF </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I agree those would be great numbers if we could hit 320cfm at .550" But all of my testing and efforts have been with out trading low or mid lift flow.It is very tedious to test and get positive results with out going backwards on flow anywhere. So far 305 cfm,at .575" is best i have gotten with aftermarket 2.02 valves. My port size under 225cc on this LS6 head.

 

LS1derfull,

You'll have to let me know what your final #'s end up like. I just received my own set of Stg.II LS6 heads and they flow like 311cfm at .550 and almost 320cfm at .600. I don't have these on the car yet, but I'm sure it will rock. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

If you are able to maintain your mid lift #'s, and still get somewhere around 315cfm or more at .550 I'd be really impressed. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

--JF

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Slowhawk:
<strong> I agree with mid lift #'s.That's why I will not post higher than .550 lift #'s.But there is a problem with a port that stalls at .525 on a cam that lifts to .561.
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yeah I would agree but with an intake in place the port wont stall at .525
A stock port on a flow bench will also stall at around .525 but with an intake on this changes.

As far as exhaust flow. These heads have killer ports. But in NA engine there is no need to max out the exhaust. Intake to exhaust flow ratio is very good with basic work to the exhaust port. Why go more unless it is a Nitrous engine?

 

If there is a few more HP in the exhaust it is worth it.I have not seen anyone compare exhaust work gains.So I'm guessing they are assuming there is nothing left there.Nitrous is on the future list of mods.

On another note.Motorcycle Heads gain the most power with the exhaust port work.Intake work gains little on the NA motor.

 

Slowhawk,

320cfm at .550 would be crazy!... If you guys get anywhere near that I'd like to see your low lift #'s as well - 'cause usually there's a trade off involved with getting really good high lift #'s.

Let me know how it turns out if you get the chance.

--JF

 

According to Lou @ LGM:

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Heads are our G2 LS6 heads, with 2.02 intake, 1.57 exhaust
They flow 314cfm at .550 lift at 28" water.
our LS1 heads flow 307cfm at .550 lift</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I don't know the port size, but if you look at the dyno graph for the G5X-2 elsewhere in this forum, the breadth of the torque curve indicates a good cylinder fill (read: high port velocity) at lower RPM. This would also seem to indicate good mid-flow numbers, as well. H82BBad is absolutely right... it's not just about volume, but port velocity, as well. I once read an article in Chevy High Performance where a LOT of SBC heads were tested and grouped by intake port size (if you go to www.chevyhiperformance.com, the cylinder head flow database is towards the bottom). They said that if you're only going to look at one number when judging a set of heads, look at the flow at .400 lift, as it is the lift area where your valve will be spending a significant amount of time (again, as H82BBad stated).

That being said, mid-flow numbers aren't really indicative of port velocity, either. The parameter to consider when looking at port velocity is port volume vs. airflow. Even that is misleading, because a port with a given volume could have countless shapes that could easily affect flow. However, it is MUCH easier to compare port volumes than port shapes, because of the complexity of the port.

 

I'd like to see a full set of flow #'s from the G2 LS6 heads as well as MTI's.

It will be interesting to see how the cars equipped with the G5X-2 "package" perform in light of all the hype.

--JF