GaaraOTS

I'm considering having my heads ported and polished, but I understand that lexus did this better factory on the RCF and GSF, would the heads from one of those be swappable with our engine? Or would I be better off having the existing heads P&P?

lobuxracer

iTrader: (2)

The heads are not swappable. The engines are depending on how much work you want to put into it.

Porting will add some, but you have to decide if the increment it will likely achieve is worth the effort. Polishing is what poor tuners do to impress the customer and ruin the performance.

GaaraOTS

How much of an increment would you expect to gain?
What all is involved in a rcf gse swap?

ljdsong

iTrader: (1)

It might help you:
http://speed.academy/10-myths-of-cylinder-head-porting/

lobuxracer

iTrader: (2)

Pretty solid information in that blog. Especially the part about, you really don't know what will happen until you try it. There is a tremendous amount of port work that is completely counter intuitive, which is why I generally don't agree with a lot of "port and polish" guys. Until you've managed to screw up a few heads, you really don't know what you're doing.

GaaraOTS

has anyone done porting on our heads?

isfvss

It will be pretty hard to beat Yamaha with all there expertise and equipment. Just see RR for a SC.

lobuxracer

iTrader: (2)

It all depends on the individual castings. If you got a core shifted head, porting might help a lot. If you're willing to accept a powerband shift, bigger valves might help but with bigger valves comes a whole lot of other stuff to make them work acceptably at lower engine speeds and flows. It's all about what you want to achieve and where you expect to achieve it. For a street engine, there are a few things you can do that will enhance low lift flow and really help the engine perform as designed, not as built. If there is casting flash or concentricity issues or other "as built" problems with a head, you can (sometimes) make things better by fixing them.

The one thing you will NOT get is a large jump in power. It will be incremental. However, choosing to do this combined with forced induction will make your engine more powerful than any other boosted one. All the gains from the conventional stuff you do translates to more power when you forcibly push more air than if you hadn't done it. It's just not economical for most people if you have to pay someone to do it for you.

GaaraOTS

so basically don't worry about it unless you go FI?

isfvss

Yes I agree with lobux all you can do to these head is port match, 5 angle valve seat cut and general clean up, you cant fit bigger valve's without huge expense, IF you could fit large valves you are going to loose velocity speed at low rpm. I have ported a lot of head to, and unless you match it to the cam specs 'which you cant change' compression levels, and a dozen more things and don't have a wet flow bench forget it.

lobuxracer

iTrader: (2)

Ports, valve sizes, and cams all have to be matched, as does rod ratio, or breathing is labored. They call it tuning because it is a symphony, and any single instrument drowning out the rest is a disaster. So, when you choose to change one thing, at least a half a dozen other things need to be changed.

I would say don't worry about it until you're looking for the finishing touch or in a very competitive series where 2 or 3 percent will make a significant difference.

isfvss

Like I said I agree, touch one thing in a highly sophisticated engine and you HAVE TO DO THE REST and have all the equipment to do it cheers.

socal3

iTrader: (2)

isfvss

I remember lobux was thinking of doing a port job on his car well we are still waiting LOL, I hope you have access to a flow bench and valve-seat cutters because that is where a lot of power can be made, more than porting on these heads cheers.

Jwconeil