Afr ?

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Jan 4, 2007 | 09:57 PM

1999 SS

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Afr ?

im looking to buy a set of AFR heads and want to know what are the pro's and con's between going with the 205's vs the 225's. i would also like to keap compresion around 11.1 what cc chambers do you think would be best and do you think im gonna need to mill them at all. what can you guys tell me?

the car is my 1999 SS with all boltons & ewp no cats with 4" exgaust fast/nw 90mm intake & tb and an fm14 cam. its pretty potent car mid upper rpm and i would like to keap it that way but also pick up some power down low.

Last edited by 1999 SS; Jan 4, 2007 at 10:03 PM.

Jan 4, 2007 | 10:02 PM

TryingT/A

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I believe 225's are for larger displacement lsx's like a 402. Your 346ci ls1 will benefit more from a smaller runner like 205 and will likely be suffer power loss from a 225

Jan 4, 2007 | 10:11 PM

The1N_only

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Quote:

Originally Posted by TryingT/A

I believe 225's are for larger displacement lsx's like a 402. Your 346ci ls1 will benefit more from a smaller runner like 205 and will likely be suffer power loss from a 225

It all depends on where he wants his power as well. Look at Patrick G he is running a set of 225 small bore AFR's on a 346 and small cam by todays standards. He seems to be making really good power all around.... Maybe he will chime in

Jan 4, 2007 | 10:56 PM

Xtnct00WS6

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https://ls1tech.com/forums/generation-iii-internal-engine/448328-afr-small-bore-225s-vs-afr-205s-346-a.html

Jan 5, 2007 | 12:29 AM

TryingT/A

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Thanks for the link xtnct. Pat is running a small cam but high lift on tight lsa>223/227 .637/.639 110LSA. I wonder if I would get the same results on my 224/224 .581/.581 on 112 pretty mild cam that I want to keep. My setup would probably suffer with the 225 vs. 205's. I guess when i'm ready for heads, I will have to ask tony.

Jan 5, 2007 | 08:14 AM

Patrick G

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Although the 225s flow lots more upstairs than the 205s, they don't seem to gain much on the dyno (we're talking small bore 346s here). The large 2.08 intake valve doesn't have enough room to really breathe. I installed the 225s and lost nothing down low and gained a slight amount up high...but there was a price to be paid.

The AFR 205s gave me better piston to valve clearance (a lot better).
The AFR 205s had better throttle tip-in response.
The AFR 205s gave me slightly better fuel economy.

Am I unhappy I made the swap to AFR small bore 225s? Not really. They're still light years ahead of most heads on the market and I have lots of room to grow should I build a bigger motor in the future.

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