I'm having problems with my lq4, hp and tq at 4800-5000rpms falling off. I thought about what others said on this forum and have now decided to install a better intake system! What would be the easyist set up I can purchase and install, I would still like to use my flex fuel 33lb injectors in the install. Does anybody make a nice set up? I've read alot and searched and it seems like this may be harder than the swap I did. Mods are in siq. Thanks

 

research an ls6 intake on this board

 

Want to buy a turn key package without alot of mods.

 

Unfortunately, a package like this doesn't exist.

They only thing that you could try is to get a SSR intake manifold and a 90mm throttle body. Thunder550 did that swap on his 408 and I don't think it required much modification.

 

Do you have a dyno graph? I can understand your TQ starting to fall off @ around 4800, but your HP should be pulling at least to 5500, if not higher.

 

So I've read, the truck intake will flow more than the ls1, about 15 cfm less than ls6 on a ported head. Horsepower should be good up to the mid to high 5k

 

What you have read and what is real, are two different things. Granted the truck intake will flow similar to the LS1/LS6 intakes from idle to 5000 ... but that is due to the long runner design, which kills top end flow. Why do you think the L98 TPI engines produced huge torque numbers, yet only revved up to 5500 rpms? It was a long runner intake port design. Truck intake only flow up to 5500rpms max. That doesn't mean you can't spin them to 6500. You can see this on the VE table of the tune, it drops off dramatically after 5500rpms (all intakes peak at torque peak). As seen on the old TPI setups, and on these trucks, when you put a shorter runner design intake on, the flow is much better up top.

 

 

I've got a 383 LS1 and a 230/232-114 cam and my truck intake pulls until 5700-5800rpms. Might be your tune or maybe the cam was advanced when it was installed....

 

Does Tahoes Graph seem very "rippley" . kinda looks like some cylinders are kickin *** while others are slackin, or theres some misfiring going on. How many miles are on that motor? and yeah, at about 4700 your TQ is droppin like a tennessee hooker.