I am going to change heads over the winter & I need an opinion. I have a 98 A4 that stays around 11:90-12:10 range. The heads are stock with the exception of an upgraded set of springs. I wanted to have my factory heads ported, polished & flowed, but I was told don't waste my time because no matter how well my stock heads were worked, they still wouldn't flow better than a set of 5.3 liter truck heads. Any truth to this? Thanks in advance for any suggestions.
p.s. the reason that I won't go with an aftermarket set of heads is because the class that I race in requires a head with a factory casting number.

Thanks again

 

the "Z06" heads better referred to by number, 243, are just what you need - call Gunner at Patriot Performance and he will hook you up at a good price. These heads should meet oem standards because they are!!
Flow will be around 300 cfm at .600 and cost will be doable as well. These are factory heads

 

I am assuming the person was referring to the CNC ported 5.3 heads. As for the stock heads, the LS6 heads flow best for a stock and the lightweight valves in a track event are a definite advantage as well. You can find these used for under $500 with low mileage.

 

I don't have a problem with how much work is done to the heads as far as CNC work, they just have to have a factory casting number. Sorry for the confusion

 

243s still flow better then the 5.3s and produce more power.

IIRC pl went to the 5.3s were the F body crowd to keep costs down.

a great PP 243 is the better option IMO

 

Whoops, OK. Thought they had to be out of the box stock

 

You people here on the forum have no idea how appreciative I am for all of the input on this matter.

 

Another Vote for the 243 heads from GM!

They will meet and exceed your needs and you can getthem in the Forum For Sale section @ a good price!

Thanks,Matt

 

Your more then welcome.

Send $20 to each of us for our servies.


























j/k

 

I did a mild port and polish on my ls6 heads and had great numbers. No flow bench numbers just dyno. Get the 243 P&P and you won't regret it

 

I am running a set of stage III 317 heads on my 408 and making great power. I do not know who would tell you that? stock 243 are one of the best heads out there! There are better heads out there but you have to pay a bunch of money to get those.

 

5.3s are popular because they offer the highest compression of any stock casting due to the small 61cc chamber size.

LS6 heads may flow more (stock for stock), and they should, they have larger runners (and compared to the 5.3s), bigger valves.

There is more to head performance than just flow. Compare two heads with equal flow numbers, and then compare runner sizes. The smaller runner head will likely be the better performer. That little thing called air velocity. AFR built their reputation offering small runner (high velocity) great flowing heads.

Although I believe Patriot recently changed, and now are actually offering 243 heads, their popular "LS6 style" heads used to be 6.0 truck castings with welded chambers to achieve the smaller chamber size...this is why they've always been cheap. The 6.0 head (317) is identical to the 243 head, except for the large low-compression 72cc chamber size.


Once 5.3s are ported and stuffed with bigger valves, they become great-flowing, high velocity heads with higher compression than the others. Definitely more to them than just being cheap.

My "budget" ported 5.3s did rather well on the flowbench:




The bottom line is consider all aspects of a cylinder head before just buying for the sake of "most flow". Optimizing compression should be a goal too when shopping for a performance head.
If you're just bolting on stock heads, then yes, the 243 LS6 heads will be the best ones to use for most hp. If you're looking at ported/modified heads, then the 5.3s become a strong contender.