Giving the LS3 More Power With Comp Cams and FAST!

With the roller trunnions in place, the valvetrain will be much more stable at high RPM.
The oil pan was removed as well as the balancer and front cover.  When that was removed the timing chain and sprockets were removed and the cam was slid forward out of the block.
Howard applies assembly lube to our new Comp Cam. The cam was slid into the block, the new Comp Cams timing chain and sprockets were reinstalled, then the front cover, harmonic balancer, and oil pan were installed.

Since Rathyna’s engine had a prior history of flakey cylinder head sealing and overheating, we obtained some ARP studs to install, replacing the stock torque to yield bolts.  The previous engine builder had probably not measured the stock bolts to see if they were within spec or stretched out and the stock bolts were wasted.

The previous engine builder had cut the valve and seat angles incorrectly so there was a lot of interference between the two. This had caused bad damage to the valves and the head and a complete loss of valve seal. We had to aggressively cut the valve seats to correct the damage so we got some oversized valves from Ferrera to give us the room to recut the seats.
You can see the weird shallow angle cut into the old valves on the right vs the proper 45 degree cut on the Ferreras.  The shallow cut dug into the valve seat putting a groove into it ruining the valve seal in short order. The Ferrera valves have a flat backside and a reduced diameter stem for better flow.
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10 comments

  1. The LQ9 isn’t the iron block version of the LS3, they’re not even from the same LS Generation (LQ9 is Gen III and LS3 is Gen IV).

    Reply

  2. Sure the LQ9 is a Gen III and the LS3 is a Gen IV but there are not many differences between the Gen III and Gen IV engines and most parts interchange. The major differences between engine generations here are some to accommodate DOD and VVT options that the LS3 does not use anyway. Where it affects you, in this case, is a single bolt vs 3 bolt cam for the sprocket. The LQ9 has a 4″ bore with the same stroke but its iron block can easily be bored to the LS3’s 4.065, all the internal parts interchange. The heads are the square port, LS3, L92 improved square port configuration and everything interchanges. A lot of Chevy tuners like the LQ9 for an inexpensive forced induction block as the iron block is stiffer under boost. Its cheaper than the LS7 based six head bolt solutions for better head sealing under pressure.

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    1. The Comp Cams Trunion has a lot more bearing area than stock. As you can see in this picture the size difference in bearing area between stock and Comp Cams. You can also see that the stock trunions were beginning to gall on this engine with a stock cam and valvetrain. Installation does require some finesse and proper use of a press. A lot of people have good luck with this kit and perhaps some of the early failures were perhaps caused by improper heat treating and installation.

      I have seen many failures of stock rockers in high-level drifting which is more brutal than drag and road racing in some ways. Check out the pictures and the galling of the stock shafts.

      https://photos.smugmug.com/MotoIQ/Project-Cars/Project-Pink-350z/i-PKXPZXt/0/cf264521/L/DSC_0817-L.jpg

      Your info is good to know and thank you for bringing it to our attention and we will be keeping an eye on them but I don’t think we will have problems. We will report if we have issues.

      Reply

    1. You are completely right, our block is bored out quite a bit to 4.065 and you can go as much as 4.090 as I recall which you can’t do with the aluminum blocks. Everything does interchange between the two motors though.

      Reply

  5. Due to Rathyna’s penchant for not maintaining anything,

    Lol a woman not take care of her car?!!?!?! Unheard of!

    Reply

    2. I unfortunately wasn’t really raised or taught to maintain vehicles. I have always been a driver, and the circles I associated with growing up never emphasized car maintenance. It was all about driving. Luckily I found MotoIQ and they’re teaching me a different way – it’s kind of a running joke with me at this point. I’ve gotten better…not quite good at it yet, but I at least understand the importance of vehicle maintenance and safety now 🙂

      TGI for MotoIQ <3

      Reply

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