I have a 2001 Monte Carlo with a 3.8 N/A Engine. I plan on doing a top swap on it with some modifications. My goal is 400HP. Since I'm sure there are some people that have done this swap or have made modifications like these im looking to find out where I fall in comparison to my goal.

I have the GM heads from an 04 GTP (series III engine) which i plan on having them ported and polished, and the valves widened up to 1.90 Intake, and 1.57 Exhaust. The LIM will be ported to match the intake runner on the heads, and will also be milled out to match an intercooler (havent decided which one yet, open to suggestions). The supercharger is a Gen V and will be be milled to match the intercooler as well. As for a Throttle body, I cant decide between a ported L67 or LS1 (suggestions would be appreciated). I know i will be going with a FWI though.
For the exhaust, I was thinking Pacesetter coated headers with 1.75 inch primaries, and a 3 inch collector, high flow cat, and a cat back system (going to be based on sound of car).
I havent decided if I should put a cam in or not, If I do, It will probably be a Comp Cams Xtreme Energy 264HR15 Blower Performance Cam. But then I would need new lifters, new pushrods, new springs, a second job...and still more money. After everything is installed I am going to have the local dealership, Ramp Chevrolet, do a custom tune. Before anyone says anything about the dealership, this dealership does a lot of custom work and tunes on vettes using HP tuner and has a good reputation.

I know with a custom tune that changes things a bit, but based on parts, what should I expect for power?

 

i think your aim os a bit high with the 400hp im not sure about it im mot sure but an ESTIMATE you will have soooo many diff estimates but my est. is close to 300

 

400 HP = Shot tranny and go turbo.

 

If you're talking 400hp at the wheels, then that's a big goal for a blower car.
Here's a list (<--clickable link) of the 3800 highest HP record holders listed by cam. I believe the comp cam's xtreme energy cam is listed as the "grand prix store comp cams HL cam" in this list.
Note that on that list though, that the cars pushing the really big numbers are vendor sponsored cars. I won't say it's not possible to do it yourself, but this is what those guys do for a living, and the cost of the build is negligible to them compared to the sales they would have made from the reputation from breaking records. A lot of those 400hp+cars are set up with really expensive heads, a built trans to handle the power, and tons of other supporting mods as well.

As far as the throttlebody - go straight for the LS1, or the N* tb (about the same - not sure if there are still adapters around for the LS1 tb, but there are def adapters for the N*, plus N* lets you retain cruise control where the LS1 doesn't). The ported L67 TB is a waste of time on a gen 5, as the inlet on the gen 5 blower is a slight bit bigger than even the N*/LS1.

I don't know whether or not you've driven a modded L67/L32 car yet, but if you haven't then I would suggest doing a minimal amount of mods initially and see how you like it.
Going from a stock L67 to a headers/3.4" pulley build was a pretty nice difference, and I ended up getting impatient and doing an intercooled/rockered/gen5 build. Honestly I can't really even use half the power I can put down so far, and I'm not even done tuning. I probably should have stuck with the headers/3.4" pulley build for a while. Not trying to discourage you or anything, but IMHO go with a more conservative build first unless you're already familiar with a certain setup. You will be nicely surprised by a pretty basic build if it's done correctly.

Good luck with everything, and keep us posted on how it works out.
-Riggs

 

here's my polish gen v you can drool at, lol!!!



400 whp? that's a big number to shoot for. my suggestion is go turbo cause with the mods in your list plus installation you looking to spend between $2500-$3000.

my mods: xp cam, pp heads, ic, and 3.29 i'll be lucky if i hit 350 or more

 

I'm going to have to agree with the others a 400 HP (especially if you mean at the wheels) S/C setup is going to likely cost more than just buying a turbo kit, and leaving your engine stock otherwise- with 1/4 of the install hassle of doing H/C.

Does neither count? I'd go with a northstar- there are plenty of adaptors out there, and its easier to make work IMO than an LS1 with the same size. Forget the L67 TB, only so much bigger you can make one- and you'll likely spend double or triple what a stock N* would run.

Have you looked into an NIC or XPZ cam yet? Should be able to make more power with either.

IHonestly, there is no way anyone on here will be able to get you any sort of ballpark for these reasons:

-Since you're not buying vendor heads, there is no easy way to tell how good or extensive your port job will be compared to the 'off the shelf' heads
-Same goes with the blower, too hard to compare how your ported blower will compare to vendor done units
-Will vary based on the tune.
-No mention of expected sc pulley size
-Varies with which IC (ie a ZZP ss will be way less than a ZZP S2/3)

240-250 wheel horsepower is pretty easy with the basic bolt ons- heads, cam, and an IC should get you into at least the low 300 whp range; but IMO there are way too many variables here.

One other thing that was already mentioned once is you will need a built tranny with a H/C/IC top swap car. The stock tranny is fine for basic bolt ons and such, but you should be well over that level.

 

Okay, so 400 is overly hopeful. As far as that pulley goes, im not sure, i plan on stepping it down until theres knock, then taking it back one size or two, depending on trip length. I guess that would make a large difference in power output.

Hows this, with the setup I mentioned above, and a 3.0 pulley, would I be able to beat my dads '03 Mustang Mach 1. Hes got like 305 HP from the factory and a Borla cat back so at most 320 HP. I just want to brag that I have a quicker car, and its only a V6.

 

I don't remember, but is the '03 Mustang Mach 1 supercharged? I think that's the Cobra...But your dad seemed smart on putting a Borla CAT back exhaust on, I think they're the best for sound and power. And I don't know much about the fine tuning and expected gains of engines, but from the sound of how much money you're looking to drop into this car I would just take it a bit further and turbo the car. I know of a 2002 Monte Carlo SS turbo charged with a near infinite number of mods that puts over 600HP to the crank.

 

the mach 1s dont have a blower on them there just the dohc 4.6. its like a mid 13 car with a good driver. i dont think its even going to take 300 whp to beat him.

 

But the 4.6 in the Mustang GT only created 260HP, how does the Mach 1 make 305?