DAPSUPRSLO

iTrader: (14)

These are the flow numbers from my heads. They did not CC the intake or exhaust runners, but the combustion chambers are 37 cc . I've gotta run a turbo piston just to get the compression down, funny stuff. In any event these are very average on the intake side, and a little below average on the exhaust. Erik is going to talk to his cylinder head guy to see what can be done on the exhaust side, and maybe the intake as well. Valve size is 2.18/1.62. Here ya go.

Nick,

I just got the flow data in on these C5r heads.

Heads flowed as follows on a 4.155 bore:

Intake:
.100 67
.200 150
.300 222
.400 295
.500 341
.600 368
.700 367


Exhaust:
.100 43
.200 111
.300 168
.400 207
.500 222
.600 227
.700 231

Erik Koenig
HK Enterprises /
Horsepower Engineering
6915 Breen Dr.
Houston, TX 77086
Ph. 281-448-1300
Fax 281-448-1305

Patrick G

iTrader: (14)

Nick, those are some killer numbers! Look at thos numbers at 4 and 5. Yikes! You're in very good hands with Erik. He's surrounded by talent (including himself). They'll get those heads knocking down even bigger numbers I'm sure.

DAPSUPRSLO

iTrader: (14)

Yeah, I can't wait to get these on mr. 434, woohoo. Shooting for 11.5-11.9 to 1 though. Was going to keep it around 11.5 to 1 but may go a little higher as the ve of these heads may not be as good as we orignally thought because of the larger ports. Erik seems to think the head ports are pretty big (270s or so) but no one knows for sure until he or someone else cc's them.

DAPSUPRSLO

iTrader: (14)

Oh, and btw, if any sponsors would like to take a crack at these for porting purposes please feel free to chime in. I've already looked at one sponsors flow numbers on a 4.155 bore and they were below mine from .300-.600 about 5-10cfm but smashed mine from .600-.800 by 5-25 cfm with a 255 cc port. Anybody who thinks they can improve these by all means let me know. Not looking to spend more then $500-800 for additional work though. Thanks.

Patrick G

iTrader: (14)

Honestly, I wouldn't look at the intake runner cc volume. With the 11 degree valve angle and different port configuation, they're going to be bigger than the LSX stuff anyway. I'd be more interested to see how the cross sectional area compares to some of the higher flowing LS6 heads out there. Erik and his buddies at SAM have gotten some LS6 heads to flow like wind tunnels. Maybe they could chime in and compare the cross-sectional areas between the two heads.

DAPSUPRSLO

iTrader: (14)

I spoke with Erik (edit: spelling) about those heads too, I think their cross section is a good bit less though and they don't stall out like mine do. I believe the 11 degree stuff has a longer port which will automatically increase volume so you're right. But I'm comparing other 11 degree stuff so it is a valid comparison. Good point though Patrick.

JZ'sTA

iTrader: (23)

Every thought about selling the heads you have and buying some already done?
The ET performance heads might be a awsome option.
I haven't seen any results yet buy they have some impressive flow numbers, many different cc option's, still use a 11 degree valve angle, and they have both LS7 and C5r aftermarket castings available.

DAPSUPRSLO

iTrader: (14)

I just got off the phone with them. I may send them these heads depending on what I here from a couple of options. Thing is I couldn't get out of these heads what they are worth and justify the added expense of a new set. The heads I have already have Del West titanium valve which are about $1300-$1600 by themselves. I think my best option is to send these heads to someone and have them worked. HRD, ET, guy in Texas, etc. are a few options.

99SS-T

iTrader: (5)

2.18 thats nuts


John

DONAIMIAN

iTrader: (18)

The flow numbers are good compared to everything else, but I could see more flow out of the head.

Tony Mamo @ AFR

iTrader: (13)

If those numbers came off a bench known to provide accurate info I wouldn't lose too much sleep. The peak intake numbers might be slightly below "average", but assuming the ports aren't monstrous in size, those type of "real world" numbers aren't too bad. The exhaust might pick up 25-30 CFM's with a pipe (or they might only pick up 10-15), so it's kind of hard to make a judgement call on the exhaust flow.

Once again, alot of the C5R flow numbers I have seen thrown around in the Matrix (390,400 Etc.), are alot higher than I, or other bench's I trust have shown. Almost 370 CFM of "legit" intake flow (with good midlift #'s) will make a buttload of power. Thats some serious airflow for ANY SBC style head. Alot of BBC small and medium sized aftermarket heads would have a hard time keeping up.

Thats my .02

Good luck with the build...

Tony M.

PS....I'm not claiming a C5R head can't go high 300's, it's just going to be more the exception than the rule if you were to take a cross section of people that own them....especially those C5R heads in the hands of "Average Joe Racer" (someone not spending stupid money on a set of "one off castings", etc.).

DAPSUPRSLO

iTrader: (14)

Heads were flowed by HPE's machine shop so I have the utmost confidence in the reported numbers. I just wish I knew the port size but hopefully I will soon. Thanks for the input guys. Trust me, I'm not giving up on these heads by any means.

Cary@Perf-Induction

iTrader: (1)

I agree with Tony. Those are crazy mid numbers. We did a set like that recently, and You can't give up those very usable mid numbers. We did the AFR heads on W2W's turbo car and those didn't have near the numbers that your c5r's have and still laid down a 6.80 pass. granted it is a turbo. but those kind of numbers are good for over 750 HP n/asp. Our C5R style casting doesn't have the problem falling over as soon because we raised the intake port another .750 over the current C5R casting. The 11 degree will tend to roll over a little sooner because of the flat valve angle.

DAPSUPRSLO

iTrader: (14)

Thanks for the reply Cary. I called and spoke with Craig. I may send these over to you guys to see what ya can do with em.

Raising the port may not work with my setup as I have a modified sb2 manifold that will go on these. I've not seen any of it in person yet though as it's over at HPE so maybe a raised port would be fine with the intake setup. Kind of doubt it though as the intake has been worked heavily for these heads. Well in any event should be interesting.

airflowdevelop

Just browsing around, and thought I would throw my .02 even though I am not a sponsor...but have played around with these heads once or twice

I would "guess" that you need to take another look at the SSR and venturi. If the port is in the 270's you are fairy short with a 2.18 valve. Most of the new programs in the middle 280's will go 109 cfm/sq" so you are pretty short for an all out head. I would bet your airspeed off of the floor is 350+ FPS. need to get her slowed down a bit, and the rest should come around. your exhaust problem is more than likely in the chamber. Ask Erik what the intake port sounds like. If you need any further help, feel free to shoot me a PM with some more specifics.

Thanks
Dennis