Phil coppney

Have an lq4 block with 317 heads. Looking to make 650 HP and as much torque as possible for my 05 crew cab. Here's what I am thinking

full port and polished heads should flow 290-300 cfm
SS valves or titanium
trunion upgrade
high lift springs
bore and stroke to 408
forged rotating assembly + pistons
stock intake (truck) and 90mm throttle body
flowmaster headers and cats

not really worried about high rev rather have torque in the low end. Ideas on Cam? Or other suggestions?

LLLosingit

iTrader: (4)

I don't see how you're even going to get close to 650/650 NA unless you get aftermarket heads good intake and throttle body and then turn some serious RPMs. 450 might be easily accomplished.

tech@WS6store

iTrader: (2)

Heads up here come the llsr guys

So thats about 500 at the wheels? Take some expensive parts...
You would also need a pretty large cam that would make driving your truck not so much fun due to the large converter also.
I would aim more for torque and not as much hp honestly.
Trick flow heads, fastlsxr intake, custom cam, and a 408 should get you there, but then your trans will need work, likely alot.
We can get you what you want, or we can help guide you to a more balanced package to make alot of tq and be fun to drive!

Let us know! or email me rpmspeedtech@gmail.com

KCS

iTrader: (20)

650ft-lbs of torque isn't happening naturally aspirated. That's about 1.6ft-lbs per cube.

You might get 500-550whp with someone really good porting those heads. You might meet your goals a lot easier with an LSA blower on a stock shortblock.

tech@WS6store

iTrader: (2)

Edelbrock makes a really nice truck blower also. looks pretty good.

speedtigger

iTrader: (16)

Yep. Sounds like positive displacement supercharger territory.

Phil coppney

The 650 targets are at the crank, if I get 450-500 to the wheel that will be good.

I have already rebuilt the trans with Kevlar bands, upgraded sun shell etc. I have a powerdyne supercharger but I am not sure it can support 408ci and high flow heads.

Looking at cam with lift of .581/.588, Duration at.05 of 224/230 with LSA of 114. That seems like about the limit for streetable. Not really interested in high rev stall converter.

HappySalesman

iTrader: (3)

As stated before, 650 isn't possible with that combination. Your biggest limiter is the factory intake, but I would also suggest going aftermarket over the factory heads. Aftermarket castings will flow 20+cfm more.

I'd ditch the factory rockers as well, they're great for low-lift cams, but at high lift they start to scrub the valves and you're gonna destroy the guides.

I'd look at a Fast 102/102 setup for your intake.

For a cam, I'd get in touch with guys like Tony Mamo, Brian Tooley, Pat G, etc. They all know their stuff and can help you build a motor to reach your power goals.

tech@WS6store

iTrader: (2)

Youll need a better cam than that. There isnt much support for powerdyne any more but if you have the complete kit and rated output of the unit, it could feed a purpose built 408. I wouldnt see it feeding a 408 above 6k too well, but a truck shifting higher than that normally isnt a good thing anyway on the street unless you want to sling a driveshaft.
kevlar bands arent always good either. its not just about putting parts in but checking clearances also.

Tuskyz28

630 horses at the crank for a 408ci is more realistic on pump gas with a hydraulic roller with a good set of aftermarket heads.

tech@WS6store

iTrader: (2)

Making that hp useable in a truck rpm range would be the issue.

07NBSChevy

iTrader: (1)

In order to make more HP with stock cubic inches, you will need a bigger cam. That will raise your HP/Torque Curve higher and higher depending on the cam.

Don't forget about the throttle body spacer.

big hammer

20:1 compression will get you there

Phil coppney

Okay, maybe a different set up. I have a powerdyne blower. It has been completely rebuilt and works great. So, with lower levels of boost 2 - 5 lbs what would y’all recommend? I drive the truck around town so the cam has to make enough vacuum to be streetable. What type of rockers?

tech@WS6store

iTrader: (2)

Some crew cabs either have a vacuum pump or hydroboost so you wouldn't need to worry about vacuum.
Ls engines arent small block chevys, youve gotta use a HUGE cam to not have the right amt of vacuum for brakes. Nothing else in a chevy truck runs off vacuum in em.
2lbs would do nothing youd need at least 5...actually youd be better off selling it and getting a roots style system like a maggie or edelbrock. Running non intercooled isnt a good idea and most of the powerdyne entry levels werent intercooled...and if you try to intercool 5lbs youll wind up with nothing at the engine honestly with an external intercooler. Overdrive it with a 10% overdrive and make some more boost, then youll have what you want, but not like a roots.
With boost you wont need more than an avg cam on a 408 to make 500 at the wheels.