[WEAPON-X]

So, before we delve into this with factual data, I am curious to see what the community's thoughts are as far as porting the heads. I'm compiling a few builds right now to lay it all out. I have heard a lot of guys say head porting nets very little, but we also all know there is a vast difference between power under the curve and peak power.

Any head porter will tell you that CFM is for suckers as there are a lot of factors that come into play with ported heads that cannot be measured on a flow bench, such as port velocity and timing.

Any good head porter will also tell you that the LT1 and LT4 heads suffer from severe core shift and I can affirm this first hand after seeing multiple sets of CNC'ed heads from a very popular engine builder that still had the OEM casting in portions of the walls.

So, anyone buying heads that aren't hand finished, is likely leaving power on the table to begin with as these places offering cheap CNC heads are doing so for a reason

So, I'll start off with a poll while I finish compiling this!

[nighttowl]

Porting the heads make a huge difference on NA engines and will make a difference on supercharged applications as well, but not with as large as an effect unless you are going for big horsepower.

[XXX ZL1]

The LT1 and LT4 head flow very well stock. I tuned a 16 SS a few weeks ago that gained almost nothing with a CNC set if lt1 heads. Car had a vortech, 9 lbs, and camshaft. A properly hand finished deal may provide some gain, but depending on price point may not be worth it unless chasing that last 10 hp. Although softening the chamber will benefit it a fair amount.

[RDBill]

I worked in a motorcycle speed shop for nearly a decade and cylinder heads may be the most important part of any performance package. Having said that I agree a flow bench and "numbers" are just about useless. A head that flows more on a flow bench won't necessarily make more HP. Someone who knows what they're doing can make a significant improvement on the LT4 heads. They are good out of the box but there is definitely room for improvement. I've looked at a lot of ports in my time and although I personally can't port worth a damn (and Ive tried) I've seen some ports that you just knew were going to make power. So yes there is some horsepower there for the taking

[Markoz28]

I’ve built a few sbc in the past and a good set of heads is always at the top of the list. My favorite for the almighty 350-427 sbc are profiler heads. Lots of power through the entire range. With that being said I feel it’s very clear that the way to build serious power in the LT4 is by upgrading the super charger and the fuel system. Seems to me that is where to spend the money. Now if you want the total package then heads would get you a better mix and a bit more power. But I’d still focus on the SC and fuel more than anything else.

[Vulcan1]

Back to back builds, everything the same except for one using CNC ported heads resulted in a 40 HP increase. 3.5k for the head work so you would have to ask yourself can I put that somewhere else for the HP to dollar? 2018 LT4 engines, 1.7L blowers, cams and exhaust.

[WEAPON-X]

To bump this up, here is the validation of our stage 2 ported heads worth their money with approximately a 50whp swing.* These two Whipple LT engines both have forged pistons, the same compression, the same cam, the same trans and gear ratio, same e70ish pump gas, and the ported head car has the same power nearly 500 RPMs sooner or 50whp more at any given RPM up until the shift point where they meet back up.* I found this pretty interesting * Our head porter used to work for/with GM having helped develop the LS7 head for example and to this day, he has always knocked it out of the park for us with his CNC ports and hand finishing.* He is the first to say CFM is for suckers LOL as the port design, valve job, and hand blending is how to get the power!**

WEAPON-X Ported Stage 2 Heads:
https://weaponxmotorsports.com/produ...nt=37648767697