goal - 425 horses.

current set up -
swirlport heads
voodoo cam
factory rockers
factory intake
True dual exhaust with headers


proposed setup-
vortec heads (polished)
single plane intake
aftermarket rollers (need assistance)

I am somewhat restricted in budget and plan on getting there over the next 2 years but my wife is a bit of a car part antagonist. what other NA applicable bolt ons would get me closer to my goal? I appreciate the feedback.

 

425 wheel hp? I'd think better than vortec heads and a big cam.

 

http://www.ebay.com/itm/SBC-Chevy-20...4AAOSwVFlULWnd

 

If you have two years I would take the time to immerse yourself in the LS swap threads on here. Find a junkyard that is reputable and has engine/tranny sales (usually around the bigger cities) and grab a lower mileage 5.3 or 6.0 with the ecm and wiring. While you have it out you can shove in a new cam, get a mail order tune and make your goal if not close. You would just need the motor mount adapters and new trans cross member and a small mod to the fuel system. You can have $1000 in this and or $1000 in the other route. Longterm the LS route will be capable of making more power and having better manners and probably be worth more if you sell the car.

 

http://www.ebay.com/itm/383-Chevy-Cr...Ivma5A&vxp=mtr

 

You could make 425 horsepower on an engine dyno with upgraded (but not ported) Vortec heads and a roller cam in the 230 @ .050" range. Single plane or RPM Air Gap intake and 675 cfm carb.
Problem is, once you transfer that to your chassis, you'll lose some of that 425 hp due to the exhaust (it's hard to beat dyno headers) and accessories.

 

I built a 350 with vortec heads, 224/230 cam, 1.6 roller rockers and a rpm air gap... it scoots pretty good in my brothers 3rd Gen.
I'd estimate it's only around 380-400 crank hp.

Skip polishing the heads or a single plane.

If you are after more power go with more cam, compression and aftermarket heads (AFR) or an LS swap. Although more money, a cammed LS motor will make more power than most mild built/cheap aftermarket head SBC builds...
I'm currently finishing up a 10:1 6.0 LS motor, single plane, 850cfm carb with a 232/244 cam. I'm shooting for a little over 500 crank hp. Next winter I plan on sending the heads to be ported and will easily gain 40-50 more hp.

 

This is great Feedback, I forgot to mention. the car already has an 850 cfm carb on it that came with it, in fairly new condition. I plan to keep it carb'd
for simplicity and heritage sake.


425 is the goal, too much power and I risk tanking the factory 4 speed.


the car is a solid 7/10 condition wise and have no ambition on ever getting rid of it. I know too many people who are out there looking for their first third gen and kicking themselves for ever getting rid of it lol.

 

No benefit to "polishing" heads... they run about the same whether shiny or not. However, VERY LIGHT porting in the bowls, emphasis on LIGHT, can help a bit; clean up all the weird steps and angles where the cutter met the casting, WITHOUT changing the shape or size of the port, and REMOVE AS LITTLE METAL AS POSSIBLE, can be beneficial.

Rollers, what? Cam? rockers? bearings?

Which one?

I'm feeling, a 6211?

Not seeing 425 HP in this, although you don't mention what the CID is, or compression, or lots of other things that might impact that.

 

Unless you have a specific reason to have 425 HP I would suggest you outline what you want the engine to do, drive and perform and let the power fall where it may. 425 at the motor with a sbc is doable in a daily driver car. For 425 wheel power it takes on a different personality.

If I were building a daily driver/performance engine I would go for the most CI you can afford. If you have a 350 then a 383 would be a good place to start. Then decide on EFI or carb. ~10:1 compression with Vortec or AFR 180/195 heads. Hydraulic cam, flat or roller with 220-225 @ 050 with a Performer dual plane intake and a 750 carb would be a good plan. 1 5/8 long tube headers and a good flowing exhaust. HEI distributor I wouldn't get too set on roller rockers or anything exotic. Some of the spec may change depending on the trans, stall (if auto) and rear gear. It also depends on what you are willing to tolerate and your tuning abilities. My little 414 is not the easiest motor to live with day to day and takes attention.

If budget permits the LS platform is really hard to compare to a SBC. That's a whole different discussion.