Numbers were good for their small runner heads:

Intake, 205 cc port, 2.02i & 1.60e valves;

.050 _34.8
.100 _69.6
.150 101.3
.200 127.1
.250 154.6
.300 181.7
.350 206.2
.400 231.5
.450 250.9
.500 265.5
.550 274.0
.600 279.4
.650 263.8
.700 265.6

These numbers are from a conservative flowbench. To give you a good basis, here is how these numbers rate against other heads

LIFT - 241 -LS6
.050 _33.8 _33.0
.100 _63.6 _65.2
.150 _96.7 100.7
.200 135.2 138.0
.250 166.3 167.7
.300 191.0 192.7
.350 210.4 213.1
.400 223.2 230.0
.450 230.3 243.1
.500 226.5 254.1
.550 226.5 257.0
.600 230.6 238.0
.650 234.6 240.1
.700 237.8 242.3

Exhaust port on the 205s cam in right at 208.5 cfm.

Other interesting bits of information;

PTV clearance will be .015" worse with these heads over stock 241s because of the larger intake valves,(free drop was .150" as opposed to .165") but the chambers are already smaller; thus, there is no need to mill these. Advertised chamber volume is 62cc, so you're going to have better PTV-clearance with these than milled stock castings at 62cc.


This set of heads had a set of Ti retainers on top of its "behive" design springs. A set of .060" shims sat on top of the seat. These springs ran into coil bind at .670" as assembled which with .050" clearance would allow you to run a .620" valve lift safely. Spring pressures were 145#s on the intake and 136#s on the exhaust.

Let me know what you think guys. This is on Thunder Racing's flowbench. Thanks to Thunder and Jason 99TA.

So, if you're contemplating these heads a few things to consider;

Already assembled with big valves
Titanium retainers
A NEW casting
Designed on a wet flowbench
Ports that are nearly the size of LS1 ports, but flow 42 CFM more
62cc chambers (no need to mill)
Better PTV clearance
Springs that are good for .620" lift safely.

I don't have any pictures of it, but before the heads left from Dart they were hand finished with a carbide cutter. You can clearly see where the valve seats were blended into the bowls and that they cleaned up the short side radius. The extra texture could also aide in preventing flow seperation as the wet intake charge will theoretically adhere to it better. You can see these marks below the valve seat and they fade away into the bottom of the runner. They also got at a few of the casting marks on my heads near the short-side turn. Wish I had pictures...

Lastly, keep in mind that flow numbers are not always a direct comparison. It's just easier to flow heads than to bolt them to a motor and plot horsepower curves. Don't put too much emphasis on flow numbers, and remember that this is a port designed outside of the confines of GM starting with a clean slate.

Ben T.

 

We need pictures. I need money!

 

Good info. Thanks for the time and effort you put forth on this. Did you by chance cc the combustion chambers?????

 

I have photo's and I also measured the valve train parts. The intake valve is 2.02, but also weighs less than the stock valve (non-LS6). Springs, retainers and locks were also very light. This is a dynamite valve train setup in my opinion. Valve springs are also nitrided, so don't use the "claw" type of removal tool on them.

 

I'm not sure on the chamber size as I didn't measure, but I have not gotten a clear answer this far;

https://ls1tech.com/forums/showpost....8&postcount=46

https://ls1tech.com/forums/showpost....8&postcount=31

Not sure what the exact size is.

Ben T.

 

Are you talking chamber volume or width? I measured my width, but not the volume. They are advertised by Dart as 62 cc.

 

I had mine milled to a 59cc..

 

i could be wrong but im pretty sure that futral motorsports checked a set of 225's and they were around 62.5 cc's

 

Hard to believe the stock 241 heads keep up with and 243 heads kick the Dart's *** on the low lift.. Damn. I wonder what a 225cc Dart would have done?

 

Actually I was there when Allan checked mine on the old car and it was 63.5cc.

Mike

 

Chamber volume. I came up with 101mm on the width.

 

I got 3.96" for chamber width when I measured, hence the use of the 6.0 GM gaskets. Although, I think GM sells these gaskets for all the GEN III's now because on the parts list they have for 4.8, 5.3, 5.7 and 6.0 engines.

 

you should enjoy the heads I kno my z06 does.

 

Vettenuts, you came up with some different installed heights for the springs, didn't you??? Are all heads slightly different enough that they'd take different shims. If yours are different than Studytime's, wouldn't that hint that Dart is actually taking the time to set the spring heights for each individual head?? The more I learn about these Dart's, the more I like them.

 

Dart 225 at 28" H20, superflow 600 2.05 30* backcut/1.60 22* backcut
Intake Exhaust
.200 140 98
.300 203 136
.400 252 165
.500 285 181
.600 285 190

Will have flow numbers on Friday when I take them back to get flowed. Lots of work to the exhaust; guide, bowl, runner, valve job, and drastic short turn. The intake side went to hell and starting talking to us at .500. We ripped out the valve job and went with our wider throat hand blended 3 angle job. More short turn, bowl, guide, and curved wall work. I will give a brief summation on Friday afternoon when we nail it down. Nonetheless, I expected alittle better, but we'll see just how much better it gets!

Brandon

 

Did you "clean" yours up? Mine have burrs in the inside from where the rocker holes are drilled and some cast crap left inside.. Was thinking about getting the dremmel out and and cleaning them up a bit.

 

ask and you shall recieve... these were flowed on the same bench as the above heads... dart 225's untouched...


intake:
.050 35.6
.100 65.7
.150 96.6
.200 128.8
.250 158.4
.300 185.9
.350 212.6
.400 237.5
.450 259.0
.500 274.5
.550 286.3
.600 294.1
.650 300.6
.700 301.2

exhaust:
.050 25.6
.100 60.4
.150 80.8
.200 104.0
.250 124.0
.300 143.7
.350 160.4
.400 180.9
.450 188.1
.500 195.3
.550 200.1
.600 204.1
.650 206.9
.700 209.3

 

People.........there is the reason why internet flow numbers can screw you up and down. What valves were you running? What backcut? Funny how you didnt seem to get turbulent and we did, curious.

Brandon

 

mine were just assembled, out the box darts... dont know about the back cut or anything...

 

Let me be the first to say Thunder Racing flow bench is about the lowest reading bench in the country.
I have had a couple sets flow there and the same heads flow on a number of other benches.
Their bench read 6.23% lower on avarage then the other benches.
My local bench flowed almost the exact same and its a JKM bench which is known to read low.
Anyways that this for what you want but I would say the heads are pretty good being on that bench.