Porting and Polishing Heads and Intake discussion.

This is an open discussion about the Pro's and Con's of Porting and Polishing heads and Intakes.

ALL Off Topic is NOT WANTED and discuraged here, so STAY ON TOPIC!

ALL Vendors and members are encouraged to participate.

Please if you are citing an opinion, PLEASE state it as an Opinion. If stating a FACT, PLEASE give references and back up to facts...

Above ALL, Please keep this civil.

If anyone wants to discuss a different modification, please begin a NEW TOPIC and continue with the above guidelines.

 

I was one of the first...not the first but probably 1 of 5 around the LX forums...to install PP heads on the 6.1 I had at the time..this was back in late 2006...best improvement in power mod I had done...and the PP heads today are far better..

 

What affect will they do to the addition of a S/C.... I assume it will definitely help the air flow, ending with more HP or torque or both. Is this overkill with a S/C?

 

Correct, they will only help the flow of the air coming from the blower.

 

You must mean this diffferent than it sounds.
I mean there are facts of over 75HP from cam amnd heads and around 35-40 with heads only and 35-40 with cam only.

 

What else do you have to change when you P&P? Anything, or can you just do that? Has anyone had any "Cons" due to the P&P? i.e. HAL not liking it, turbulance issues, etc?

 

I was one of them too. I did the PPP/INDY Exteme heads with the Polished intake manifold that had a very light and rough CNC job that barely went into the manifold. Basicly the only thing available. I had no complaints. I also put my 2nd cam in at that time. Pretty large for those days. Still would be considered pretty big for today.

 

He meant that it will only help, not hurt your flow.

You don't have to change anything else, but to take full advantage of your now increased air flow you'll need a bigger cam. Cons from polished and ported heads/intake are very little if they're done well. If you get ports that are too large (opinion: like Indy's generation 1 6.1 heads), you'll lose air velocity which leads to turbulence. A good porting job on our heads is more about changing the shape of the port than hugely increasing flow. Our heads already flow a LOT for stock heads.

 

Hey Ron hope you don't mind but since this is about heads what are the pros and cons between cnc ported heads vs. hand ported?

 

Most good CNC'd heads are finished with some hand porting. The biggest issue with hand porting is that it's very hard to maintain the same specs from cylinder to cylinder, let alone one set of heads to the next.

 

Opinion/Question:
Wouldn't this depend on the max flow of the heads and max for the blower?

If you're not at the max for either I'd think the approach would be to step up the blower? If you're using a blower wouldn't the only reason to PP your heads be if you're at the max flow for the heads? Or can that always be increased by stepping up the blower? On the other hand I suppose if you're at the max for the blower then PP heads might get you further before swapping the blower for a larger one? We're assuming the intake manifold is not a restriction right?

 

great question.

A short answer as I am NO expert. lol

When building any motor, whether for F/I or N/A, all specs should be taken into consideration. Cam specs, P&P flow, valve size, and of course amount of flow a F/I will be giving. Heck, even the throttle body could have a play in the build...

 

You don't have to be at max flow to take advantage of porting, whether your N/A or boosted. The issue isn't that the head isn't flowing enough, it's that there are places to gain velocity and pressure (tapering the end of the runner).

Say your head flows 350 CFM, but there is a 90 degree dog-leg before turning down to the valve. After porting, you still flow 350 CFM, but the port has a nice sweeping curve to make the same 90 degree transition. Which one do you think will deliver better (not more) airflow?

 

My heads are designed for FI. Could be the only ones in existence that are. I have many contacts that know this stuff like the back of their hand.
All heads flow more air under boost. But they will still have limitations. My heads have bigger ports, bigger chambers, and bigger valves. Custom designed by one of my engine builder friends. He did a custom CNC program for them. They are top fuel quality, a work of art. The valve springs are one of only 5 sets.
So, will my heads flow more than stock heads, hell yes, will they flow more at low boost, hell yes. Will they flow more than regular cnc'd heads running more boost than me, probably not. To many variables. Cam is the biggest contributor. How far does it open the valves, how fast does it open the valves, how long are the valves open, FI wants a pretty big difference in exhaust duration or intake. We've forced more air into the chamber, so we need more time to get it out.

 

My heads are also designed for FI...same as Hal's.."bigger ports, bigger chambers, and bigger valves"...I got mine from Roe Racing..same as the blower...he sells two different PP heads...FI & N/A....for Viper engines that is..

 

Courious would it be still benifichal to port and polish at 90k or should a full rebuild just be done???

 

The PP would probably benefit but going that far into the engine it would make sense to get the bottom end taken care of...if you can swing the extra cash..my 02 cents..

 

Mine are as well Hal.

 

so probally not then im guessing...

 

One of the thing's you don't want to do on a N/A application is just hog the hell out of the heads.I dislike the Indy's for that reason.HHP,PPP,FRI and Inertia all try to shape the port for velocity as well as flow.The Indy port flows well but bottom end power is affected horribly IMO.They are probably insane at 8k rpm.......where we will never see.