52172

iTrader: (2)

Heres my 853 casting ported heads flow numbers

.100-69 cfm intake 54 cfm exhaust
.200-125-109
.300-187-144
.400-243-162
.500-277-178
.600-299-189
.650-306-194

Just for comparison

PREDATOR-Z

Guys, no offense, but when will you get through your heads that comparing flow#'s from different flowbenches doesn't give you any comparison picture?
I challenge any of you to take the same heads to 3 different benches and get exactly the same output.
I went from 11.62 to a 11.14 swapping to PRC's 5.3L/2.5 (Both were tuned for nitrous), and they still gave me very decent gains. an average ~ .45 Et decrease is very respectable in my book for the $1400 I spent on those heads.

Jason 98 TA

iTrader: (4)

Here's a flow sheet from a PRC Stage 2.5 done independently on Thunder Racing's SF1200. Jason @ Thunder said the typical set of AFR 205s flows about 288-291 on this bench...

We've now got a even better flowing setup that flows alot better on the .400 & lower numbers, but it atleast gives you guys some independent info.

SF1020 bench, 3.900" bore, Radiused entry on intake side, exhaust port flowed open

Intake Exhaust
.050 36.1 30.0
.100 70.0 57.2
.150 103.9 83.6
.200 139.1 110.4
.250 168.3 130.0
.300 198.0 150.1
.350 222.9 165.3
.400 244.4 177.3
.450 262.1 194.1
.500 276.7 202.2
.550 288.4 208.5
.600 298.8 213.3
.650 304.7 216.9
.700 278.4 220.1

Jason 98 TA

iTrader: (4)

Great results Predator Z!!

Ragtop 99

iTrader: (7)

Everyone keeps talking about what is coming down the road. Well, anyone who has been in the LS1 game for at least a few years knows that no matter when you decide to buy, six months or year later someone will offer a better head or same quality head that is less expensive than what you just bought . The battle over heads looks a lot like Computer Chips...every 18 months another set comes out that kicks *** and other competitors are forced to either keep improving theirs or cut their price in order to compete.

If you want heads in 2005, buy what is proven to work today and don't worry about what might exist in 2006. If you wait untill 2006, I guarantee you that something better or cheaper will be looming on the horizon for 2007 and you'll be facing the same dilemma as to buy or wait. The only difference is that you will have gone another 6 months or more without enjoying 30 - 40 rwhp.

equandt

iTrader: (2)

My PRC's shipped yesterday!

Ragtop 99 makes a very good point. I remember when your header choices were Mac's or the original Grotts. Buy a set of quality heads. You can't go wrong with either the PRC's or the AFR's. Talk with each vendor about your goals and buy from the vendor that you feel comfortable, fits your goals and wallet.

Good luck.

The pissing contest regarding "how vendor X heads flow" stops on the street or track. I don't care what they guy next to me head's flow. I just want to win.

Ragtop 99

iTrader: (7)

Headers are a great example. They have improved and their are some good low cost options. Hell, my lid set me back $150 about 6 years ago and that was bought on a GP. On an inflation adjusted basis, they are about 1/2 that cost now.

steveo346

iTrader: (18)

go with afr's they are freaking awesome!!

Jason 98 TA

iTrader: (4)

We just finished up flowing our newest version of the Stage 1.5 5.3l cylinder head.

The Precison Race Components 5.3l Stage 1.5 cylinder head features a 2.02 intake valve & stock exhaust valve. The valve setup on these cylinder heads allows customers with large camshafts (like the MS3) the ability to get a great flowing cylinder head without needing to cut valve reliefs!

Here's a flow sheet from the set of 1.5 cylinder heads going to a customer with a MS3 camshaft The 1.5 5.3l cylinder heads will retail for $1350!!! Like the 2.5 cylinder heads the 1.5 heads will feature complete hand finishing & detailed tweaking until the head meets Freddie's strict standards. The cool thing about the 5.3l casting is customers can also get a bigger exhaust valve & still clear large camshafts!

SILVERZZ28

iTrader: (3)

How would they compare to the 225s?

jrp

iTrader: (16)

who's too say those numbers werent backed up on a different bench....

i feel what J-Rod brougt up a while back still rings true about bench comparisons and power.

https://ls1tech.com/forums/showpost....92&postcount=2

Phil'sC5vette

iTrader: (4)

All Ive got to say is this thread is 2000 hits behind mine when I asked the same question 2 months ago.


I bought the AFR 205s after the thread

PREDATOR-Z

That is exactly what I'm trying to say:

TVWilkes

It was alrerady offered to compare the AFR vs. PRC heads on the same car.The latest R&D stage 2.5 head from PRC is the best 5.3L head available,period!Freddie and I have worked very hard in making the heads the best available.

JS

iTrader: (4)

The AFR kills the PRC 1.5 on the exhaust side..There's no comparaision and u guys fall slightly short on mid lift on the intake side too?

I understand that your only running a 1.55 but thats a big difference...Whats your 5.3's runner CC too..

SS1875

iTrader: (34)

Personally I will take my LPE ported/blended 59cc 2.02/1.60 heads over either of them. Numbers are numbers, it all boils down to the performance you get with the setup you have, everybody likes one thing or another. The nice part about it is we can make our own choices as individuals!!