243's vs 5.3L heads
243's vs 5.3L heads I plan on getting a set of heads for my 98 Formula, I plan on keeping the car N/A with the stock bore.
What are the pro's and con's of each?
How do they compare stock?
How are they once there p/p and had a valve job?
What are the pro's and con's of each?
How do they compare stock?
How are they once there p/p and had a valve job?
A stock 243 with a good valve job and nice cam will lay down over 400Rwhp and net a 11.xx at the track all day long. Same with a set of 5.3's but its all in the mix of parts. Is this a track car or street whats your goal??
That's a great question, I was wondering the same.
Maybe someone can list which mix of parts would net best results. Especially considering 5.3 heads can be found all day long.
I know, search. I think something a little more localized, like this thread would be more benificial. An in depth comparison of all options would he great.
Maybe someone can list which mix of parts would net best results. Especially considering 5.3 heads can be found all day long.
I know, search. I think something a little more localized, like this thread would be more benificial. An in depth comparison of all options would he great.
in reality there is no "best" combinations....its just what works best for you.... on the dyno and track i haven't see a whole lot of difference between the two heads. i think many can concur. the 5.3's seem to run cheaper, but dont hit max numbers the 243's do. but on a budget its hard to argue between the two. i think the 5.3's are a good 3-400 dollars cheaper. and that said, even some p&p 243's are hard to beat for the price...
do some research, there's plenty of people having awesome luck with both heads...
do some research, there's plenty of people having awesome luck with both heads...
My car is a street car with very little track time but that doesnt mean I dont want some power to the wheels.
Goals are a very fast street car with approx 425-450hp to the ground N/A running on 93 octane.
Goals are a very fast street car with approx 425-450hp to the ground N/A running on 93 octane.
get which ever heads you can get cheaper than and call it a day...if you only want 425-450 hp either one will most likely get you there plus full bolt ons...
when you want to hit 475+ is when the big money starts to come into play...
when you want to hit 475+ is when the big money starts to come into play...
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TECH Resident
Joined: Jan 2009
Posts: 873
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From: oakland, ca
i would go with a good set of 243s..Prc or patriot if price is your number #1 concern..Usualy 5.3s are used to bump compression but the same compression bump can be had with milling the 243s..also for around the same price take a look at the tfs 220s..i went with the prc ls6 stg 2.5s for my build.
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The 243's have a better port, the 5.3's have a smaller combustion chamber.
I'd rather have the 243's any day, especially if you find them with hollow intake and sodium filled exhaust valves.
I'd rather have the 243's any day, especially if you find them with hollow intake and sodium filled exhaust valves.
I'm running a set of stock 5.3's I sent off to Bo White when he was still doin car heads. They outflow stock 243's & bumped my compression. So I picked up a good amount of low end & they also carry a decent ways in the upper RPM's. Definetly good enough for my daily driven street car. The extra low end grunt makes it very enjoyable to drive in general.
Its all in your complete combo though. I'm chokin mine off right now with the stock intake. I can literally feel it lose power above 5k RPM's. Hopin to finally switch to a LS6 intake & get it tuned by the end of the year.
Its all in your complete combo though. I'm chokin mine off right now with the stock intake. I can literally feel it lose power above 5k RPM's. Hopin to finally switch to a LS6 intake & get it tuned by the end of the year.
If you plan on just swapping stock heads and then do some work to them down the road, get some 799s. They are the same as the 243s, but in the price range of the 706s. Main difference being LS6 243 = lightweight valves and non LS6 243s = 799s
I run 5.3s and the compression bump is great! It produces lots of low end power and my FAST 90/90 set up helps with the top end. It is by no means a slouch on the top end but my car isnt a highway car. Its a 1/8 mile car. I always have my 150 shot for the top end. 
stock the 243/799 are worlds better
after porting the line isn't so night day
if you want stock get the 243/799...if you are going ported look in the classifieds for ported heads, I can't find anyone who will port my 799s for a decent price, you can likely get some good heads for $600-700
I only gave $250 for my 799s and can't seem to find anyone who ports at a price that makes them cheaper than if I had just bought ported heads
after porting the line isn't so night day
if you want stock get the 243/799...if you are going ported look in the classifieds for ported heads, I can't find anyone who will port my 799s for a decent price, you can likely get some good heads for $600-700
I only gave $250 for my 799s and can't seem to find anyone who ports at a price that makes them cheaper than if I had just bought ported heads
