When Rathyna had her car tuned, the AFR was set at a very rich 10:1, an AFR which we feel is much too rich for a stock compression NA engine. If the AFR was set to something that we feel more appropriate for a motor of this level of build, like a still conservative 12:1, we feel that the engine could pick up another 10 hp easily. We may revisit the tune later.
We also feel that the engine could benefit from a header with a larger primary tube diameter like 1 7/8″ vs the current 1 3/4″. We also feel that the engine could benefit from a larger throttle body, like the FAST 102mm. With these changes, the engine might make as much as 430 whp and possibly have more revving capability.
With the car being run as is, it is much improved. Of course, just running right is a big improvement but the added rpm, means that Rathyna hardly ever hits the rev limiter now and when she does, it’s hardly noticeable, quiet and smooth. No more weird, throbbing, abrupt rev limit that was a combination of lifter pump and the ECU cutting fuel. The added power is making quite a difference too. So far it looks like we have cured the car’s penchant for overheating as well. Rathyna has been driving better than ever thanks to the power, wider powerband, and the extra revs.
SOURCES
Comp Cams
FAST
DeatschWerks
ARP
10 comments
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).
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.
I would highly avoid using the compcam trunion upgrades. They fail at an extreme rate.
Just check out some of these failures.
https://www.corvetteforum.com/forums/c6-tech-performance/3546465-fail-comp-cams-trunion-upgrade.html
I’ve read nothing but bad things. Ton of posts of exactly the same bearing failure. They just have a poor design.
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.
Lots of recent failures of the comp kits.
https://www.corvetteforum.com/forums/c6-corvette-zr1-and-z06/3802785-failed-comp-cams-trunions.html
I would not use them. Better alternative is either straub kit or CHE precision.
https://www.corvetteforum.com/forums/c5-tech/4130290-che-trunion-upgrade.html
LS3 is not the same bore as LQ9. 4.065 Bore vs 4.00
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.
Due to Rathyna’s penchant for not maintaining anything,
Lol a woman not take care of her car?!!?!?! Unheard of!
Men can do this as well… Has nothing to do with sex.
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