im looking to get 205 afr heads and wonder what it would make over stock ls6 heads. i have a 240/244/112lsa cam ls6 heads every bolt on with x pipes. right now im making 600rwhp and 610rwtq on nitrous and 450rwhp and 400rwtq off the bottle. so what would a 205 afr heads give me when tuned or should i go with 225 afr's

 

Lets try this in the Internal Engine section.

 

If I had a cam like that I would go 225's. The AFR 225's are more for racing applications and with a cam like that you are probably racing.

 

yes but its also a DD

 

if you have a good set of ported ls6 heads, you could gain nothing depending on what's on the car already.

 

On that big a cam AFR205 cc is defeating the purpose. I would choose a head that flows at least 320/.600 with 70/80% of that on exhaust.

So yeah, 225s would benefit you more on top.

 

You would be surprised how well the 205's would work. Sure the 225's might make a little more power upstairs, but with that large a cam and stock displacement the lower and middle part of the curve would be noticably softer. Dig around and find independent testamonials about how the addition of 205's just wakes up the entire package and still screams upstairs.

With my original package (stock short, AFR 205's, ported FAST 90, 224/228 cam etc) I went from 480/435 to 606/645 with an NX kit and a 100 shot. Only a .052 nitrous jet if I recall.

The thing is with spray, even if the 225's were 10-20 better up top (the most they would be IMO), a slightly bigger N2O pill easily covers that, and opting for the 205 allows you to still enjoy and experience all the things the proper sized cross section and high airspeed of the 205 design can offer you (much better punch in the throttle in the lower/middle part of the curve).

You guys will soon see results from a very respected board member who went from 205's to 225's and recently back to 205's (with a more aggressive package) all of which on the same size 347 forged short. I wont let the cat out of the bag, but the new 205 combination flat out rocks and you guys will see some dyno results and driving impressions soon.

IMO, a 205 is simply the best tool for the job....its sized exactly where a mid 300 cubic inch (or slightly larger) engine really needs to be, especially if it's a dual purpose street/strip application. There is a reason we designed it that way even most of the Internet experts at the time said it was to small and wouldn't work....blah, blah, blah. Some of the highest producing average Joe combinations (independent results, not shop cars) have been made with that head in mild to wild stock displacement applications....

Hell....consider the handful of people making good power with them on 402 combinations as well. Personally, I would encourage you to run the 205 head, but honestly you couldn't go wrong with either.

Thats my three cents anyway....

Good luck....let us know what you decide to do.

Tony

 

Patrick G is a good exemple when he did his switch. He found little to no loss below but a ~ 15 rwhp on top.
So it really depends what you want to use them for. If a healthy amount of strip is involved, 225s would benefit more; for below curve power I still think AFR 205 are the best 15* angle head out there..
Also keep in mind that with such a cam setup (meaning at that level) , one day your stock block is gonna say byebye. So the 225s will benefit extra on the addded cubes you'll choose.

 

i plan one day to bump the displacment to 383

 

LOL....Patrick G just might be the well respected member I mentioned above

Oooooops.....there goes that cat.

Im sure Pat will chime in soon with a teaser of what he has going on....with the abridged version being a cam thats closer to this posters grind and a switch back to 205's

Even a 383 will work well the the 05's btw...

Check out the extensive testing I did below

http://www1.ls1tech.com/forums/showthread.php?t=384450

Tony

 

I had the AFR 205s and loved them. When the small bore AFR 225s came out, I was one of the first to try them out. I was somewhat disappointed. I lost no low end torque, but I only gained 3-5 rwhp from the swap. Same cam, same exhaust, tuned to the max. In the process, I lost the stellar tip-in throttle reponse that the 205s gave me and my fuel economy went down. Not a good trade-off in my opinion.

Things got good again once I swapped to my "torque coming out of my ears" 223/227 .636/.639 110LSA cam. Made 475 rwhp and 429 rwtq. But as my skills tuning cars with big cams improved, I got the bug to change up my setup again. I have recently pulled off my AFR 225s and Torque Cam and swapped in some AFR 205s and a larger cam. Preliminary results show power WAY above my old setup and the street manners are almost identical. Gas mileage is back too. Had to bump my rev limiter to 7200 and it's still too low, LOL. I have some ground-breaking exhaust to fab up for it in the next few weeks so I will post dyno numbers then. Stay tuned.

 

cool thanks

 

Well then that pretty much seals it. 383 is standard bore (well 3.905) so the AFR 205s would still shine all over.

Ahh Patrick, couldn't help it eh. Had to go and change setups again. Pretty soon you'll beat your 13 converter swap

 

You know how it is Mark...changes to your car keep you in love with it for a long time. Just wait 'til you see the pictures of my new Fikse wheels on my TA. Talk about LOVE.

Honestly though, these new AFR 205s seem to be the hot ticket for my quest to exceed 500 rwhp with a stock displacement LS1.

 

Like I said AFR castings are the best 15* VA heads around (IMO). I know a guy who bought my AFR 225s 72cc here for a turbo 370 and he pumps over 1100rwhp on ~1.8 BAR boost (25psi or so IIRC). No O-rings and he hasn't lifted the heads yet. Those are ammazing for FI applications.

I wish I never sold them to him

 

How would the AFRs 205 do with a FI setup. I am currently trying to figure out what type of setup i want to do for my car. I am aiming for a FI setup in the future but, I also want a decent NA setup before I add the FI. Most likely i'll have N2O before the FI.

 

Pat G, can you update this thread in the future with a link when you post the results? i don't want to miss that post. Thanks!

 

What changes did they make to the 205's?

I spoke to Tony about a 6 liter specific 205. Did that come out?

 

That shouldn't be too hard to do, just enlarge chambers for a 4.0 bore, change seats on intake and slap on a 2.04 or 2.055 valve in there. Runners would remain untouched

 

Because of the popularity of bolting up AFR 205s to LS2s and 402s, Tony Mamo has been opening up the chambers to 4.0" bore on select 205s. A side benefit to this for us small bore guys is that the low and mid-lift flow numbers improved dramatically, even with a 3.900" bore fixture.

The heads I'm running now have stock AFR 205 2.02"/1.60" valve sizes and current cnc port job, but the chamber is enlarged to a 4.0" bore and valve job better accomodates the unshrouding of the valves. The flow numbers at .200", .300", and .400" on a 3.900" bore are better than any head I've seen on the market (including TFS and ETP). The flow gains seem to help on the dyno too as my numbers have climbed in all categories. Again, when I'm all done, I will start a new thread and give a detailed synopsis of everything.