Hey guys, I just purchased a set of Gen-1 Cast Iron H/O heads (basically, standard heads for the V6/60 MPFI motor) that have been professionally ported (not polished, but blended) and have been installed with a set of brand new SI Stainless Steel valves at the stock intake / exhaust size. The heads were original cyl heads that had been cleaned / magnafluxed / planed, and then re-installed with all new performance springs, retainers, SI valves / 3-angle valve job, and then ported to the standard Felpro gasket-sized opening.

This is going to be going on a crate Gen-1 3.4 V6/60 that I purchased to replace my 2.8 V6/60.

Just had a couple of questions and wanted some thoughts. Assuming my 2.8 puts out 140hp, and my 3.4 puts out 160hp, is it unreasonable to assume that I can achieve 180-185hp with these heads and the following other improvements:
- Port-matched intake w/ larger 57mm throttle body
- 17lb Injectors
- Port-matched intake, runners, and plenum
- 1.52:1 roller rockers
- H272 Crane Cam
- 2" mandrel-bent exhaust with larger CFM catalytic converter and hogged out exhaust manifolds.

I'm also considering going with a full 2.5" exhaust piping from the manifolds to the muffler... but I'm concerned this might be overkill (anyone have any thoughts on what's optimal for a 3.4 with moderate improvements)?
I'll also likely be taking my entire intake plenum, runners, and intake manifold and running it through an extrude-hone... which I know will be pretty expensive, but the goal is to keep the engine looking totally stock, while giving it more modern performance.
I'll also be running a modern ECM and not the outdated 80s ECM.


Would really appreciate any thoughts on my estimate on whether or not ~180-185 is reasonable to expect.

I'd also like to hear if anyone has ever used these valves ... they have a swirl design on the ports to direction the air to essentially make them more efficient, and are also slightly thinner just before the dish to effectively allow more air into the chamber (sans grinding out and making larger ports). Average hp I've seen from those who have tested it (really old threads) is around 2-3hp in the mid-to-upper rpms. I'm also interested to hear from anyone who has ported these cyl heads. I find it interesting that they used the exact same cyl heads without modification despite an increase of over half a liter from the 2.8 to 3.4. I'd imagine if they were restrictive for the 2.8 at all, they will definitely be for the 3.4.


Thanks!

Should be able to get around 180hp with that setup. Are you running dual 2" or single. If going single I would go minimum 2.25" or 2.5" would make the most power. If you can put some headers on it, even ported the stock exhaust manifolds are restrictive.