Tony Mamo @ AFR

iTrader: (13)

If you had to pass the sniffer IMO this cam has a bit too much overlap. As soon as you can start clearly hearing a camshaft loping at an idle your crossing the line of passing the sniffer.

The same build with a 234 single pattern may have sneaked thru and would only have reduced peak output around 25 RWHP or so.....but fattened up the bottom of the curve and peak TQ a bit as well (maybe 10 more RWTQ with the smaller cam).

Regarding the heads, most of the aggresive metal removal was spent re-configuring the combustion chambers. The ports themselves are more optimized in the key areas....valve job, short turns, CNC transitions, etc. but more blending than actual metal removal. Essentially helping a production piece cut by a machine better mimic the highly romanced prototype it was copied from.
I bet the actual port is only a couple of cc's larger if that. Thats a winning combination however because all the extra airflow (the entire overall improved flow curve) is moving thru essentially the same size cross section improving the airspeed and inertia of the incoming and exiting charge and more effectively filling (and evacuating) the cylinder on every power stroke.

If you were to compare the flownumbers of Greg's 205's to what we advertise on our website its quite a bit stronger at every lift point and the port is still 205 cc's give or take. Part of that is the larger 4" bore its tested on but most of it is from the chamber and port work.

Tony

vader99

iTrader: (4)

Tony, would your "tweaked afr 205's" be worthwhile (performance and dollar wise) if you were just going to use a stock 346 ls1 block with a mild cam (224 - 228 .570" lift) and ls6 intake?

Or, would the tweaking not be worth it on a mild combo like that?

So, in other words, how much extra rwhp/rwtq would result from bolting on a set of your "tweaked" 205's compared to just bolting on a set right out of the box onto the above mentioned mild build-up??

Tony Mamo @ AFR

iTrader: (13)

To remove a set of heads and just do that in and of itself it wouldnt be very cost effective. If you did the same thing but stepped into a similar but more aggressive cam (like the one I featured in my former 346 build), added a ported FAST 90, and did the heads, the car would be a whole lot more explosive when it went back together.

Whats the extra work worth on a 346 CID.....probably around 10-12 additional ponies, but its worth twice that (or close) on a semi-aggressive 4" bore build like a 402/403 etc. Even a 364 with its larger bore would take better advantage of the chamber mods and improved new flowcurve. I initially worked on a 205 like this for a 4" bore engine and the results were very good. When I finished with the head I threw it back on the flowbench to see what it would do on a 3.900 bore and it liked it as well.....just not as much as the 4" bore did which makes perfect sense due to the larger mismatch between the chamber OD and the finished bore size. Long story short is I helped a few guys with 346 builds with exactly the same thing and saw positive results from that, all for similar reasons....the added low and midlift airflow on both intake and exhaust. Its just that the 4" stuff benefits more than an engine built around the smaller 3.900 bore.

Perhaps the more "famous" of those 346 builds is Pat G's F-body which was covered in detail in the following thread....

http://www1.ls1tech.com/forums/showthread.php?t=732392

If you wanted to tweak every last pony from your 346, it would obviously be a good move, not to mention would leave you with a killer head to step into when you finally purchase that stroker you have had rattling around in the back of your head....LOL (If your the type of guy considering spending the extra money on the porting, its just a matter of time before you purchase a larger engine....LOL)

Anyway....hope this helps

Tony

swmn

Nice job, again Mr. Mamo. Mike, I have been meaning to call you for a few days.

Could someone fire up their air dyno and think about a street sleeper here please?

What if I put a LS6 intake on this with whatever $$ throttle body, catted LTs on the back porch. Any hydraulic roller cam, plenty of advance. If I am willing to settle for say 425-450 peak hp how flat can this torque curve probably go? What can this motor bring to say 1750 rpm?

Jonesing for the video.

thanks

camarokid94

iTrader: (2)

i love my 205s on my 402. im gonna reset the cam to 113ICL and get some stepped headers and go redyno it before the th400 if i can. going for that 520 mark plus the lowend and throttle responce of there heads makes it hard to drive on the street very quickly all it wants to do is spin the tires. takin some bottom out will help. but i do love the throttle responce.... you do great work tony ill give ya that congrats.