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243 Heads?


DBTKDT

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I have been thinking about putting some 243 heads on my LQ4? I think this a complete just bolt them on and go your mary way. What would my compression raise up to? Any ideas how much gain i could get with the 243's? I'm also thinkinking of then putting on some 1.8 rockers to give me a little more lift. I don't think i would ever do a cam so that would be a simple bolt on at that time of swaping heads. Does this make sense at all? Any other thoughts? I already run 93 with my Wheatley tune so i'm aware of the bump in octane needed. Thanks

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Well, 243's are a good way to increase compression. With a stock 64cc combustion chamber on the 243's and your LQ4, your looking at about 10.5:1 SCR vs roughly 9.4:1SCR with the stock 71cc 317's...gasket dependent. The bump in compression will be nice along with the better designed dual quench area of the 243's. I would highly recommend doing a cam at the same time for a big added gain. Consider a 3000+ stall converter and you should have a perky combo.

 

As for gains on just the head swap...I have read results of about 20HP from the added compression alone. The 317's and 243's flow just about the same however the testing by WCCH has shown a small increase of flow (stock 243's vs stock 317's) going to the 243's most likely due to the better designed combustion chamber. Keep in mind that true LS6 243's have sodium filled valves that will give a slight bump in powerband due to their weight reduction over the steel ones. So if you are looking at 243's and wish to just bolt on and go, look for heads off a true LS6 engine and not the "LS2" version.

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Well, 243's are a good way to increase compression. With a stock 64cc combustion chamber on the 243's and your LQ4, your looking at about 10.5:1 SCR vs roughly 9.4:1SCR with the stock 71cc 317's...gasket dependent. The bump in compression will be nice along with the better designed dual quench area of the 243's. I would highly recommend doing a cam at the same time for a big added gain. Consider a 3000+ stall converter and you should have a perky combo.

 

As for gains on just the head swap...I have read results of about 20HP from the added compression alone. The 317's and 243's flow just about the same however the testing by WCCH has shown a small increase of flow (stock 243's vs stock 317's) going to the 243's most likely due to the better designed combustion chamber. Keep in mind that true LS6 243's have sodium filled valves that will give a slight bump in powerband due to their weight reduction over the steel ones. So if you are looking at 243's and wish to just bolt on and go, look for heads off a true LS6 engine and not the "LS2" version.

 

 

Thank you for that great info! Looks like you really know your stuff. I was looking to just use oem gaskets and be done. would like to do a cam but don't want the truck loping like a race care. Any thoughts? I know i can do a cam cheaper than rocker arms and get more gain too. Looking for some good thoughts. Thanks guys!

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You will be way more happy with a cam than the rockers. Just having a cam don't mean it will lope like a drag car. There are a ton of stock sounding cams that will give you the performance your heads can use. You can go with a low lift, duration, and high LSA( 116) cam that will sound almost if not stock, and give you some good low end grunt combined with the better flow of the heads and high LSA to give you some decent mid-upper power.

If you decide on going this route with a cam, and you stay with a low lift can (under .560) you can put the ZO6 yellow springs on or some beehives for springs. but you will need some upgraded injectors because you will be maxed out if your not already. Wheatley will hook you up with a reflash, and you will be able to enjoy the new power.

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