I have a vortec (350) engine with the following mods;
CAI w/K&N
De-screened MAF
Shorty headers
Full dual exhaust w/dual cats
Underdrive pullies

Everything else on the engine is stock to the engine (intake manifold, CPI, Cam, heads, etc.

Stock it's rated at 255 hp, but I see these Vortec long blocks all over the place with well over 300 hp -even TBI ones (ski boats have 310-320 hp vortec TBI engines).

What is the limiting factor in the truck version? The cam? If so, would 1.6 or 1.7 rockers show a fairly substantial gain?

Anyone know the stock lift of the Vortec engine's cam? Thanks.
-Tom

 

There are a couple of "Vortec" cams I've seen, but even the highest lift one is on the low side of .400"..... .424" on the exhaust IIRC.

A 1.6 rocker would take that to ~.450"

That's OK since unmolested Vortecs reach peak flow about there, so it should only help. 1.6 rocker will also increase advertised duration ~2-3* at the valve. That's not a lot, but it should only help.

Keep in mind that you'd get better results from a bigger cam.

 

Thanks AJ

Do you know if valve float would be a problem as high as 5000 RPM w/1.7 ratio rockers??

I know a cam would be a MUCH better mod, but I honestly don't feel like getting that into the motor. Lazyness. Also the gain I "need" is small. Maybe 10 hp.

Here's what's up. My Brother has a '99 xcab Tacoma 3.4L, 5 speed. My 1500 5.7 5 speed, x cab, 4x4, would destroy that thing in every aspect of performance, including gas milage. No big surprize there though. For Christmas, I helped him (or should say I DID) install a TRD supercharger that he had bought.

Since it's winter, RMR is closed so we did a couple little impromtu stop light show-down's and he has me by a door length about half way through 3rd (75-80mph). I can't have that! I'm figuring/hoping 1.7 roller rockers or will get me there due to them helping a lame cam, on an otherwise good over all system.

I would LOVE to spend less than $200 to get ahead of him again, to the $2000 he just spent.

So hopefully that explains the lazyness on the cam project. The truck is more than adequate already. Tows my boat great, has plenty of punch, and get over 20 MPG on road trips. I don't need to improve that enough to tear into the thing, but if I could bolt on some rockers and put my bumper in front of my brother's....

 

I think 1.6 rockers is all your going to get for a small block. 10hp wont catch you up to him.
Want to beat him for as cheap as possible? Nitrous......:lala: