Getting a 520hp 427 to a true 650 HP level is not going to be cheap.
ALL the 520hp parts will need to be changed to parts Capable of 650hp. Induction/valvetrain/exhaust/heads
A true 650hp N/A 427 is fairly radical and will not be cheap.
Get a better job and or buy a nitrous system. easiest cheapest way to get from 520hp to 650 hp.
If you really want that much more power N/A build a large CID BBC. 496++CID + solid street roller cam big carb fully ported heads or aftermarket aluminum.
If you want to supercharge it change the pistons to lower the compression ratio.
7.5:1 for max performance with a roots style blower and premium pump gas.
650+ superchaged power from a low compression 427 is quite possible.
177 blower and 950-1000cfm carb or bigger 671-871 style blower + two 750's or a Procharger/Vortech centrifical.
New blower friendly solid street roller.
Hyd roller cams in a BBC are for the girlie man . (especially on a blown BBC).
A N/A street strip 650HP 427cid BBC that runs on pump gas would look like this.
Fully correctly ported oval ports. true 10.5:1 cr. Comp XR286R-10 cam or XR292R-10 solid street roller cam.
(or similar 248 to 260deg solid street roller cam .650+lift) with suitable valvetrain.
Vic JR/ Holley strip dominator oval port single plane intake 950-1000 cfm carb. Or a BBC street tunnel ram and two 750's
Big tube 2"+ headers
92+ octane gas
8" 10" 4000+ stall converter and correct gearing.
Just cause your oval port heads are ported and have big valves does not mean they are working.
They probabily need some more attention to get them right.
Again nitrous is the cheap path to big power gains, at low cost.
Beyond this there is nothing cheap about 650hp.
Does your buddy actualy have a use for a real 650 horsepower ? (actually race it)
Or is just a POSER with no money and big dreams.
What is the current engine combo (details). What is the budget?
There is probaly lots of room for improvement on the current combo for more than the
Has this truck ever been drag tested to establish the real performance level?
What is the performance gain goal from this point. Beyond "I want a 650hp tuck"
Last edited by F-BIRD'88; 10-06-2012 at 02:19 PM.