vortec head and its limits....

[bdi]

what and when would a vortec head begin to fall off. what mods are necessary to support a 560 lift hyd roller? heads have already been cut for big springs and had the bosses milled. what port work would help? any suggestions. i do know that these heads will work til 7k with some work.....

 

[Doober]

I'd say some port work (more on the exhaust side) & screw-in studs.

 

[bdi]

forgot....the screw in studs are done . wasn't sure where on the ports , that needs to be cleaned up. any sites or magazine articles on porting these heads?

 

[Doober]

I've come across a few online, so they're out there, I'll do a little lookin' & see if I can find 'em.

 

[Doober]

I'm reading this right now, learning a bit myself. Also talk to D&A Machine Shop on here, he may have some good Vortec info for you.
http://www.nastyz28.com/forum/showthread.php?t=56505

 

[D&A Machine Shop]

Hey guys I'll try to post some flow bench figures later.
And yes if done right some port work can help but if it's not done just right
then it hurts the lower lift flow numbers and will cause the heads to be lazy.
Basically we've found that most of what worked on earlier Chevy heads doesn't always work the same on the vortec heads.
We've seen as much as a 100 HP drop because of a botched valve job.
More later.

 

[cutlass389]

I'm no expert but from my extensive reading about vortecs they are done making MORE power at 5600. You can spin 'em higher but won't realize any additional hp. Same story with hydraulic lifters. Above 6000 they will pump up and hyd rollers are HEAVY. Even modified, the max USEABLE lift is around .500. Vortecs claim to fame is the good low lift flow and amazing velocity to produce killer torque. 170cc runners are not gonna' support enough air to supply 6000+ situations. My view is to match them with a dual plane intake and a midrange(2000-6000) hydraulic roller cam for incredible torque in the real world rpm range. I'm in the high 11's with a dual plane, stock vortecs with beehive springs(915's), a .492 lift cam with the wrong LSA and not enough duration, shifting at 5200. Shifting at 5500 didn't produce any better times. If you want to make 'er shriek, get some big port heads, a solid cam with the best springs you can get, a single plane intake, and a whole lotta' convertor 'cause there won't be nothin' below 4000 rpms.

 

[D&A Machine Shop]

Ok I finally got the chance to post some flow figures for the vortec heads.
I couldnt get my scanner to work so I had to take a picture of them.
This is a before and after test the before is a stock port with 1.94 valve the after is fully ported with a 2.02 valve.
For the exhaust the stock port is with a 1.5 valve the after is fully ported with a 1.6 valve.

 

[slimbo]

those would support up to about 450 or 475 it looks like. with a small solid roller and a rpm air gap they would make a nice combo. something like a xr286r maybe? whats the cc of the runner after the porting? with that cam power should be good till about 63-6500

.576/.582
248/254 @ .050
110lsa

 

[D&A Machine Shop]

I didnt cc the runner on the ported head but I can tell you it was not much bigger than stock because I didnt increase the cross section or the raise the roof of the port very much at all. The stock vortec head engines that we build for dirt track are up close to 500hp with 460tq The engine with the ported heads was over 550hp with almost 500tq but both are at 12.5 to 1 compression.
I will try to post some dyno figures some time this week.