Atilla the Fun

With stock 193s from an LO5, the flowbench says: .100" is 62/50 cfm, .200" 116/97, .300" 149/130, .400" 162/134, .500" 168/135 .600" 170/135. So I installed a stainless, swirl-polished valve with undercut stem and 30 degree back-cut. I did a 5-angle valve job, and I lightly ported away any sharp edges. No port reshaping or enlarging, just the sharp spots. After all that work, here's the result: at .100" I found 3 cfm. At .200", I found 5 cfm. At .300", 3 cfm. .400" was 4 cfm, .500" was 4 cfm, and .600" was 5 cfm improvement. These heads do not respond. For comparison, I found an 882 head off a truck 350, an 882 that left the GM plant with 1.72" intake valves. At .300" it flowed 149 cfm, .400" was 173, and .500" was 179. Eve these out-flow the swirl-ports And the LO5 heads do outflow the LO3 heads, not because of the slightly larger valves, but because the ports do have a slightly larger cross-section.

Machabre

Yeah, I just did a research project for school and compared a stock 193 LO5 head to a stock 083 L98 head on a Superflow SF-600 flowbench. My results were not as good as yours though, but I did not use a radius plate or clay or anything like that around the intake port.

I got 62/49 at .100, 112/91 at .200, 138/125 at .300, 147/139 at .400, and 150/142 at max lift (about .480).

For the L98 head I got 56/44 at .100, 113/96 at .200, 150/129 at .300, 173/139 at .400, and 179/142 at max lift (again, about .480).

Flowed em at 27.5 inches of water, give or take .5 lol. It was kinda difficult to hold the valve steady and adjust the flow **** and watch the dial indicator and all the water menometers at the same time lol...

Atilla the Fun

I was on a brand-new 1020, not an old 600, and this one was fully electronic, with every option, but your lack of a radius, even a clay one, is obvious by your numbers. I have the numbers for an L98 aluminum head I did, somewhere in my files.

Machabre

Yeah, I was figuring that no radius would shave about 20 cfm off the peak... Does it matter which exhaust port you use? Cause I used one of the middle ones, which had a hole in the port pocket for the EGR. Also, I didn't put a pipe or anything on the exhaust port.

91_5.7_TPI

iTrader: (2)

You guys might want to look at this thread...
Garage Ported 193s
.500-------------224.3--------------------215.6

Atilla the Fun

As I said, the bowl isn't the choke point, and I chose to not grind away at the choke point, because the results would be unrepeatable without CNC porting equipment, and those heads are NOT worth CNC porting. I can get 1.94-valved LB9 heads past 224 cfm, no problem. And despite the less-efficient chambers, I'd rather use 882s than 193s.

91_5.7_TPI

iTrader: (2)

I'm pretty sure hand porting was pretty successfull for years before CNC equiptment was brought onto the scene. Not saying you can get those exact results, but someone who knows what they are doing or Fast355 could get the same numbers I would think.

Fast355

iTrader: (2)

If you don't touch the choke point, the opening to the swirl ramp, you can expect the results you obtained. Even putting 2.02 intake valves in them would not help at all with the choke point in place.

No offense, but 882 heads SUCK, I would MUCH rather run Swirlies than those boat anchors. Its not all about flow. The swirlies will make peak power with as little as 26-28* total timing and that greatly adds in efficiency and torque.

Atilla the Fun

Now you're getting argumentative in an educational thread. More than 99% of the members of thirdgen aren't porters, and while they could pick up a grinder, these aren't the heads for them to be grinding on, never mind what flow numbers I could get. I have flowbench results I don't post, and swirl results I'll never post, because they're of no help to anyone. Flowbench results are good for 4 things only. And I'm not gonna post my best numbers if how I got them is not easily duplicated by just anyone. I can get consistent shape, cross section, cc and flow from port to port, but the 99% aren't there yet if ever, but the 99% can do bowl blending and have their results be worthwhile on heads that aren't swirl-ports or Vortec intake ports. As for the 882 vs 193, I did this swap for a guy with a '91 C1500, from the 193s I've already posted results for, to 882s I'd ported, And at the same time we switched from the stock convoluted-dish pistins to flat-tops. The 882s I did made best power at just 32 degrees, and with no other changes, he gined 38 rwhp, despite still being at 9:1. And that's not the only time my 882s with flattops proved better than ported 193s with stock GM dished, either.