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Old 01-07-2019, 12:15 PM
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Default Which heads?

Wondering which heads would be best for a turbo 4.8. have 2 options in mind since I can find both fairly easy and not that expensive. Would I be better off using stock 706 heads that come in the motors or would 241 heads be better for it? Hoping to reach about 6-700hp with it. The more details for each option the better for helping me decide. Thanks in advance
Old 01-07-2019, 01:20 PM
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Whatever heads come on it.
Old 01-07-2019, 01:34 PM
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Keep the 706s

https://www.hotrod.com/articles/surp...der-head-test/
Old 01-07-2019, 02:20 PM
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What do I need to do with the 706 heads before I put them on? The ones I pulled off were ruined. One had a crack in it and there was coolant in a couple cylinders and the other one I ruined myself trying to remove the manifold the correct way and breaking 2 of the bolts off in the head. Things didn't go to well trying to extract them. I can get a set of 706 heads from the pull a part for cheap though so what needs done other than a thorough cleaning?
Old 01-07-2019, 05:42 PM
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Originally Posted by Grizzly76
What do I need to do with the 706 heads before I put them on? The ones I pulled off were ruined. One had a crack in it and there was coolant in a couple cylinders and the other one I ruined myself trying to remove the manifold the correct way and breaking 2 of the bolts off in the head. Things didn't go to well trying to extract them. I can get a set of 706 heads from the pull a part for cheap though so what needs done other than a thorough cleaning?
I'd have a machine shop inspect them, pressure test them, lap the valves and clean them up. You could spend more porting them, but then I'd honestly start considering aftermarket heads.
Old 01-07-2019, 07:24 PM
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I'd do 243 heads if you need to buy a set of heads.
Old 01-07-2019, 11:10 PM
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Originally Posted by wannafbody
I'd do 243 heads if you need to buy a set of heads.
Don't do this.. Lol I did this. terrible idea Slowest spooling turbo lag from no compression everrrr. 4.8's with a 243 head net an 8.8:1 compression ratio. Keep the 706's mill them 20. and run the SUM-8715 and let it eat!
Old 01-08-2019, 01:57 AM
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I don't wanna do any machining to anything if I don't have to. Just looking to refresh everything I can that's reusable and send it. It was a $200 dollar motor and my first build so I don't expect it to last a lifetime. Just gonna have fun with it and build something bigger in the mean time the correct way for big power... What are some other options I can do with them?
Old 01-08-2019, 02:39 AM
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Milling heads are CHEAP! Like $100 or a tad more. Do it!!
Old 01-08-2019, 02:55 AM
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I would if I was taking the build way more serious but I'm too cheap to do it for this one. Lol. Any ideas on head gaskets? Always read about the ls9 gaskets being top dog but would they be good for a 4.8?
Old 01-08-2019, 07:12 PM
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Originally Posted by Mavn
Don't do this.. Lol I did this. terrible idea Slowest spooling turbo lag from no compression everrrr. 4.8's with a 243 head net an 8.8:1 compression ratio. Keep the 706's mill them 20. and run the SUM-8715 and let it eat!
I didn't realize that compression would drop that low.
Old 01-08-2019, 11:30 PM
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Should I get new lifters and push rods or would I be able to get away with using factory ones?
Old 01-09-2019, 05:42 AM
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Originally Posted by Mavn
Don't do this.. Lol I did this. terrible idea Slowest spooling turbo lag from no compression everrrr. 4.8's with a 243 head net an 8.8:1 compression ratio. Keep the 706's mill them 20. and run the SUM-8715 and let it eat!
Since it was mentioned, how is that ghost cam? Anyone use it?
Old 01-09-2019, 02:23 PM
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Originally Posted by Grizzly76
Since it was mentioned, how is that ghost cam? Anyone use it?
check this out...

https://ls1tech.com/forums/generatio...ady-track.html

Old 01-09-2019, 02:50 PM
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I was thinking the SUM-8716 for mine. Not sure on a turbo to go with it. Any budget friendly ideas on a combo?
Old 01-10-2019, 07:19 PM
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Is there a reason other than a slight compression bump that you wouldn't run the small bore 862 heads?
Old 01-10-2019, 10:27 PM
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Nothing other than possibly being slightly misinformed. That's why I came here to ask. I've seen both ways done but am unsure which way is the best way. Obviously using the stock ones was my cheapest bet which is great but, if the other way was a better way to go I wouldn't mind to spend a little extra you know
Old 01-11-2019, 07:47 AM
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Originally Posted by Grizzly76
Nothing other than possibly being slightly misinformed. That's why I came here to ask. I've seen both ways done but am unsure which way is the best way. Obviously using the stock ones was my cheapest bet which is great but, if the other way was a better way to go I wouldn't mind to spend a little extra you know
If you wanted to invest in them you could have them ported and machined for the larger 2.00" intake valves and gain some more. I'm just guessing here but for a boosted application I suppose people opt for the larger cc heads to keep the compression down in order to throw more boost at it. Perhaps the smaller bore heads will allow the turbo to spool faster.
Old 01-11-2019, 07:55 AM
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I'm not sure how it all works. I have read that lower compression is better for more boost but you don't wanna drop it a hateful amount. It's just my first build so I don't wanna throw 8g in parts at it and destroy it the first time I start it. Lol. I just wanna set it up for 600-700 hp range and throw it in something to have fun with for street/strip purpose. I will do a better build on another one if I like the results with this one.
Old 01-11-2019, 08:10 AM
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Originally Posted by Grizzly76
I'm not sure how it all works. I have read that lower compression is better for more boost but you don't wanna drop it a hateful amount. It's just my first build so I don't wanna throw 8g in parts at it and destroy it the first time I start it. Lol. I just wanna set it up for 600-700 hp range and throw it in something to have fun with for street/strip purpose. I will do a better build on another one if I like the results with this one.
The compression was fairly low for the 4.8, think around 9.47:1 for the earlier ones like the LR4.



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