GMPP LS3/L92 Hand Porting.
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GMPP LS3/L92 Hand Porting. Just got a set today and I'm ecstatic about being able to put them on my G8. Only thing is, I wanna make this job perfect. I noticed these heads are rough on the intake and exhaust ports when i was checking them our and I was hoping I could get some advice on what to use/do to improve the flow. This will be my first time porting heads but I plan on taking a lot of time to do this and I'm good with my hands. What do you guys recommend so far as tools and methods to make these heads slick? P.S. I'm also going to be installing a 221/226, 567/564, 114LSA cam from Cam Motion, and 10Lbs of boost from an MP1900 Maggie. Hopefully that's enough info. 
Thanks guys,
Robbie.
Thanks guys,
Robbie.
Im not sure on the porting, but I see in your SIG you are going with 1.8 RR's? if so when the cam was Spec'd was that included in the equation? will the ramp rates not be too aggresive?
Just my .02, looks like you'll have a beast on your hands.
Congrats
Just my .02, looks like you'll have a beast on your hands.
Congrats
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Thanks for chiming in! No I didn't include the Rockers but, corrected the lift is going to be roughly .587, .583. I have the proper springs right here too I'm hoping for well over 600 RWHP, maybe 650. I'm going to be doing all the tuning and I'm quite giddy about it 
I'm hoping for well over 600 RWHP, maybe 650. I'm going to be doing all the tuning and I'm quite giddy about it Thread Starter
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OEM heads with big valves is the best description. The intake/exhaust ports are rough. Part number 12629063. I've seen people do this with great results. And no I'm not widening the ports I just wanted to know how to make them smooth.
Those heads in stock configuration flow about 340 cu ft per minute at .600 lift..as a point of refference a good set of CNC cathedral port heads will flow 315-320 ...if you do not know what you are doing you will probably do more harm than good. Plus you wil have hard time duplicating the work in the different ports...that is the beauty of CNC port work it is all exactly the same...If you look at heads that have had CNC machined porting you will notice that they are not smooth in the runners. This aids the fuel air charge not hurts the flow of the fuel and air charge. If you would like to find out what really works call Brian Tooley the owner of TEA or Richard out at West Coast Cylinder Heads. You will be enlightened by people who know what works and what doesn't. You also may have valve train control problems with those 1.8 rockers. Many people have experienced that problem when using the 1.8 ratio rockers on agressive camshaft lobes and considering the size and weight of those particular valves I would not be surprised if you had that problem occure.
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No joke huh? I didn't know that about heads. All the ones that I have dealt with are smooth as glass. Thanks for the info though. I guess I'll leave them alone. So far as the Rockers go, these are the first ones ever to be machined, and unlike Yella Terra's or SLP parts that have side loading issues with bigger cams, these are ground to accommodate to the lobes with lightweight valves so you don't get the traditional clatter, and other Valvetrain issues you would with the Big name guys. I'll take pictures when they get here. Besides that, this cam isn't really all that nasty. It lopes slightly and doesn't need a Tq Converter. It's all kind of an experiment though. Thanks for the warning too. Any more info that I should know? Thanks.
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I just did a set of heads for my 427 build that were rough cast like yours, only with ls7 titanium and sodium exhaust valves. I cleaned them up with a little porting in some areas and picked up about 12% on the exhaust and 8% on the intakes. Making sure your intake matches perfectly when torqued down will help also. If I was boosting it like you and had not ported before I would leave them alone...that 10 psi is going to push through the imperfections just fine.
ive always smoothened out my intake and exhaust ports with no problems, start off by using the roughest sandpaper to get ris of all the roughness and work your way down to a 400 then go back up to a 80 grit, add mothers wax and youll get a shiny mirror finish
with you running boost, focus on rounding any sharp edges/polishing the combustion chamber and cleaning up the exhaust runners. I wouldn't spend too much time on the intakes. Just fix any imperfections.....
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My build is nearly completed. I'm going to the most legit header man I know of as soon as I'm done. Mark Wilson at Wilson Header. He's building me a custom set of Ceramic Coated Long Tubes in which we will port match them perfectly and he will also fit the exhaust gaskets to the heads and file them perfectly. This dude knows what he's doing, and he also builds some sick CAI's.
My build is nearly completed. I'm going to the most legit header man I know of as soon as I'm done. Mark Wilson at Wilson Header. He's building me a custom set of Ceramic Coated Long Tubes in which we will port match them perfectly and he will also fit the exhaust gaskets to the heads and file them perfectly. This dude knows what he's doing, and he also builds some sick CAI's.
Good luck with the build. Get some PICS!!!
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You dont want to have the headers the same size as the port.
Read Bill Grumpy Jenkin's 1976 "Small block chevy book"
He did all the grass roots, trial and error testing you can think of and power was always lost power if the primary tube and the ex port match. Most likely from ex reversion being such a factor on bigger cams I assume.
Read Bill Grumpy Jenkin's 1976 "Small block chevy book"
He did all the grass roots, trial and error testing you can think of and power was always lost power if the primary tube and the ex port match. Most likely from ex reversion being such a factor on bigger cams I assume.
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You goin for the fastest G8 in town or something? You make it sound like you NEED all of this stuff in order to have a working motor. People run intakes and headers that aren't lined up perfectly all the time, esp with these motors, its not an uncommon thing to see when bolting them in. Just make sure everything is flush and torqued down correctly is the most important factor. That little .0005'' sticking off to the side of the intake track isnt going to stop much, esp with 10psi on top pushing it thru.
Good luck with the build. Get some PICS!!!
Good luck with the build. Get some PICS!!!
And to be honest yes I did need it because a Cylinder Head once got hurt a long while back and wasn't repaired correctly, so I got these GMPP heads and I wanted a neat lopey little cam that I could use with a Stock Converter. My DoD cam had a flat lobe 
Anyways, all this was done and I wanted to see if I was a good enough mechanic to do it all myself. Turns out I was. Did the whole thing in 12 hours. And well, I am just your average kid that likes to go fast so I decided if I'm going to go fast, I wanna go really fast. Last test on street tires for my G8 in the quarter was 11.6 with a crap tune. This time I've got the tune pretty close and I feel like busting a 10.9. Thread Starter
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You dont want to have the headers the same size as the port.
Read Bill Grumpy Jenkin's 1976 "Small block chevy book"
He did all the grass roots, trial and error testing you can think of and power was always lost power if the primary tube and the ex port match. Most likely from ex reversion being such a factor on bigger cams I assume.
Read Bill Grumpy Jenkin's 1976 "Small block chevy book"
He did all the grass roots, trial and error testing you can think of and power was always lost power if the primary tube and the ex port match. Most likely from ex reversion being such a factor on bigger cams I assume.
Actually fastest Magnacharged G8 in the country. I already have the title for here in N.M. There's a twin turbo Corvette Z06 that's been screwing around here on my street that's been needing his *** kicked for awhile though. And to be honest yes I did need it because a Cylinder Head once got hurt a long while back and wasn't repaired correctly, so I got these GMPP heads and I wanted a neat lopey little cam that I could use with a Stock Converter. My DoD cam had a flat lobe Anyways, all this was done and I wanted to see if I was a good enough mechanic to do it all myself. Turns out I was. Did the whole thing in 12 hours. And well, I am just your average kid that likes to go fast so I decided if I'm going to go fast, I wanna go really fast. Last test on street tires for my G8 in the quarter was 11.6 with a crap tune. This time I've got the tune pretty close and I feel like busting a 10.9.
And to be honest yes I did need it because a Cylinder Head once got hurt a long while back and wasn't repaired correctly, so I got these GMPP heads and I wanted a neat lopey little cam that I could use with a Stock Converter. My DoD cam had a flat lobe Anyways, all this was done and I wanted to see if I was a good enough mechanic to do it all myself. Turns out I was. Did the whole thing in 12 hours. And well, I am just your average kid that likes to go fast so I decided if I'm going to go fast, I wanna go really fast. Last test on street tires for my G8 in the quarter was 11.6 with a crap tune. This time I've got the tune pretty close and I feel like busting a 10.9. 
... please post a time slip when you make your runs would really like to see the results... Thread Starter
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I'm up about 50 RWHP, and I failed to mention I'm going with Drag Radials. I wish I could tune that well!