I'm planning on building a motor setup for around 400-420 fwhp and currently I have a set of 906 l31 vortec heads on my current setup with a cyclone intake. From the research on these heads it seems like i'm going to have a pain getting all the work done on them to run a good cam, is it worth keeping them and using them or just selling them and running another cheaper head, like a 2.02 camel hump head or something else? what would you guys do? currently its a stock 98 vortec motor with shorties, 2.5 inch y pip exhaust to a 1 chamber flowmaster, cyclone intake and holley 750 vacuum sec. carb. stock roller cam.

 

If you have the cash, i would keep them. you can buy the beehive spring to accommodate the higher lift, unfortunately the cost factor is pretty expensive. i have those heads(havent run them yet) with a pretty good cam 495.,503 lift with a 269.,276 duration, 112 lobe separation. ( my slash key is not working). from what people are telling me, it will be a monster on the street> this is my first build so i can only tell you from my amateur knowlege.
but from the research I have done these heads flow quite well for a factory head. unless your going with aluminum heads i would stick with what you got>

 

I appreciate the input, do you think I should just to the spring work so it will accomodate a bigger lift or should I install larger valves or mill them or port them? I'm thinking of running the cc306 cam which is a .510/.540, duration at .50 is 236/244, I forget the lsa and I plan on running a weiand stealth high rise intake and 750 holley vacuum sec.

 

Box stock Vortecs will flow enough to support over 400 hp with the right cam. No porting, milling or valve upgrades are needed unless you're looking for that last bit of power. The cam you are specifying is slightly larger than what I run. With the right compliment of parts, it should be a fairly stout engine.
Here's a link to the Beehive spring upgrade as has been suggested.
http://www.carcraft.com/techarticles...ade/index.html
Good luck.

 

thanx man, I very much appreciate the advise. What cam do you suggest? I would definately like to be in the 400 fwhp range.

 

Check these builds. It'll give you an idea.

http://www.popularhotrodding.com/eng...ock/index.html

http://www.popularhotrodding.com/eng...ine/index.html

http://www.carcraft.com/techarticles...ne/index1.html

 

If that is a 2.5" pipe from the cat back, it will not support 400 HP.

 

What setup for the exhaust do you recommend me running? I dont want to run long tubes since my car is very low.

Thx skinny for the info.

 

I have the 906 heads and its alot harder than you think to have 400hp. Alot of the popular buildups make about 370-385hp at the flywheel without any accessories. But alot of these guys are here are running 13.0s and high 12s and im trying to make my way down there. Personally from all the time and money i've put into my car I would

A. Buy a crate engine and sell your motor
B. Buy a car thats already built for the drag strip for 5-8k

Just my 2 cents, these magazines say budget buildups and all this stuff but when it comes down to it you will find yourself in a money pit. I stock had a 92Rs and built a vortec 350 as my specs say and ive managed 13.80s w/o slicks. And its hard to find someone to help you get your **** right the first time without getting ripped off

 

My RS is low too i had a guy do custom dual pipes 2.5" with a crossover and glasspacks. Shaved off over .5 second

 

http://www.superchevy.com/technical/...exh/index.html

Point well made. Witness my own combination with a single 3" (no cat) exhaust and a 30 series Flowmaster muffler. Chassis dynoed at 285 rwhp and similar torque. This exhaust system flows 300 cfm max. Indications are there is easily 10% to be gained should I open up the headers (with suitable collectors of course). That's getting very close to the 375/380 chp level depending on how your discount the drivetrain loses including a convertor that doesn't lock up.
As it is the car runs consistent 12.7x at 105.
From what I've read, an exhaust must be capable of provided 2.2cfm of flow for each horsepower before power loses are incurred due to a restrictive system. How you go about it is a different matter. Certainly not an easy task on a lowered 3rd gen.

 

If I were to do it all again and didn't have any engine components to start with, I'd buy a crate engine too. I can't imagine I could rebuild my current engine for the price of todays crates (and warranty too).

 

my goal is to dyno around 300-310 at the wheels. Currently my car runs a 13.9 on a non posi 3.08 rear end with just intake and exhaust and a crappy carb so I'm curious to your set up. I definetly understand your gripe about budget build ups in magazines, whenever I read them I'm alsways like I dont have 3500 in my pocket to build a motor. I can build a 1500 dollar motor to go 12's but I was curious because these vortecs, they are already on my motor but I know nothing about them. If 380 is all I can get at the flywheel then fudge it. I really want to run 12's but if I have to run different heads I will but I'd rather use these since, well since I already have them lol.

hey skinny, do you think it will be better than to run a 3 inch y pipe to a 3 inch cat back to my 1 chamber flow? I really dont want to change the muffler since I love how these 1 chamber flowmasters sound.

 

plus I dont have money to go buy a crate motor or a whole car

 

If you can find out what the cfm of the chambered muffler is, you'll have a better idea if it will be a restriction (and limit power output) or not.
That being said, a single 3" is certainly better than 2.5". Whether a single 3" pipe (right to the tailpipe) regardless of the muffler would be a restiction is something I'll be able to answer once I do some back to back testing at the track this season.
One of the gripes I have about magazine engines is that most are performed with an optimal set of headers (not to mention the lack of accesories as was mentioned). Power output will be enhanced. Let's see some testing with y-pipes and street mufflers and then check the results.

 

True, I'll have to look into it, I think my best bet is to run 3 inch from the headers to the muffler, if my 1 chamber restricts some power than so be it, I like the way it sounds. Do you think that cc306 cam from comp would work skinny? I'm going to have the machine shop do all the spring work on the heads to accomodate a .550 to .580 lift. so I'm wondering if I should run that cam with 1.6rr or 1.6rr on intake and a 1.5rr on the exhaust. or maybe another cam? I ran that cc306 in my lt1 and it performed very well. But thats a completely different motor I understand.

I also noticed you had your heads milled in your signature, think I should mill mine similar?

 

I don't know much about the cc306 however I did find this article.
http://www.f-body.com/forum/printthread.php?t=9063
It's argued that the Vortecs stall (in terms of flow) at lifts beyond .470". However conventional thinking says if you use a cam with lifts beyond this limit, you will be at that limit longer. I think 1.6rr are always a good idea unless of course the cam is designed specifically NOT to use them.
The milled heads are a result of having the 2 or 3 thou taken out of them to correct for slight warpage. It results in a somewhat smaller combustion chamber. It's not something I would persue unless really required.

 

Yea true true, Ive seen a lot of people run way larger cams with stock vortec heads. The cc306 can be used with 1.6rr but with 1.6 the intake will be around .540 but the exhaust will be around .580 thats why I was thinking of putting 1.6 on the intake and 1.5 on the exhaust thus the lifts would be around .540 on both and I wanted to mill them a bit to bump up the compression from the stock 9.4 to well something higher.

 

"my goal is to dyno around 300-310 at the wheels. Currently my car runs a 13.9 on a non posi 3.08 rear end with just intake and exhaust and a crappy carb so I'm curious to your set up. I definetly understand your gripe about budget build ups in magazines, whenever I read them I'm alsways like I dont have 3500 in my pocket to build a motor. I can build a 1500 dollar motor to go 12's but I was curious because these vortecs, they are already on my motor but I know nothing about them. If 380 is all I can get at the flywheel then fudge it. I really want to run 12's but if I have to run different heads I will but I'd rather use these since, well since I already have them lol."

Most vortec setups dyno 260-275 rwhp. My cars at a performance shop now changing my wrong length plugs, correcting my timing, and adjusting my carb. I've been using .460 length plugs when vortecs take .708. So my spark was being covered in the threads still causing it to not run at peak performance. My timing was also low so naturally i ran a 13.9 at 100. I'm picking it up tomorrow so i should feel a world of difference!

But If I were you i would run a comp xr276 cam, run 1.6 rr on the exhaust, get a performer RPM like i have, beehive springs, 750 holley mech or vac secondaries. You should be pushing the limits for vortec horsepower

 

Thx for the info, I was thinking of running the weiand stealth high rise intake, a holley 750 vacuum sec but really want mechanical sec. I have a posi unit that needs to be installed and a set of 3.73 gears. Someone also told me to run the xe282hr cam. what do you think?

 

Yea go with that cam, I like the extra RPMS and lift

 

alright, thx for the help. what do you think about the intake choice?

 

I would go with the performer RPM, great intake from 1500-6500 RPMs which will give you great all around torque over single planes.

 

Sounds surprisingly like my combo. 1.6rr (full rollers) all around though and an RPM Air Gap. Vacuum secondaries because I like the economy and a well curved distributor with advance all in by 3000 and plenty of vacuum advance (for that economy thing again).
If this wasn't a daily driver (as well as a weekend warrior) I may have chosen the XR282HR. However I do like to drive (across the country more than once with 20+mpg) and it's said that if you're going to make a mistake with a cam, make it on the small side.

 

do you think that xe282hr cam is too much for a street car? a friend has a cam with a 298/300 duration, lopes like hell, is a solid lift and was 5 spd like me and it had good street manners. and the stealth high rise is dual plane and the power band is from 1500-6700

 

Not at all. In our group there's a 67 Chevelle with a 350 and the next step up from the 282, the XR288HR. It has excellent street manners, nice lope at idle although it produces only 7" of vacuum and still manages hi teens (20 mpg/cdn at one point) for mileage on the highway. That engine has the AFR195s with an Air Gap intake. A little over 10:1 static compression (which is low in my opinion). Not blindingly fast at the track with a 12.45 @ 110 however he's sorting through some convertor/transmission issues and should be in the 11's before the season is over.
Thoroughly streetable.
I edited an earlier post regarding having the heads milled. I hadn't mentioned that it was done to correct a slight warping on one head. I would NOT recommend doing it unless absolutely necessary.

 

Oh alright, I wont be milling them then, thx man for the info.