Head Porting - Worth it?

[Shelby]

be aware that heavy porting esp around and includeing cutting the valve guides down will shorten the guides life

[jszucs]

Tim, I agree with your comments. I think what Mike was trying to point out is that YOU, yourself can clean up your Cylinder Head ports because of casting imperfections. Yes. We all know, or some of us know that doing porting on a Cylinder Head or heads requires experience in such things. I am shocked at Kevs estimate for doing Port work ($400.00 to $800.00) ??? That seems like this to me:

 

Either the Machine Shop didn't really want to mess with it.

or

They were just trying to rip him off.

 

Bill

 

Not really... it's going to depend on what they are doing. This is also going on the assumption it's brand new fully appart ECT.

 

But easy 100 and hour to test on good flow bench.

Figure doing the valve areas is 300

Easy 100 an hour for the person doing the porting and between doing some porting and puting stuff back in it and then testing you got a few hours right there.

[Tim_C.]

be aware that heavy porting esp around and includeing cutting the valve guides down will shorten the guides life

Yes, that's why I only do that on the cars I don't drive as often. And we try not to go much into the seat at all. Just enough for a smooth transition to the unshrouded area.

[Tim_C.]

 

 

Tim, I agree with your comments. I think what Mike was trying to point out is that YOU, yourself can clean up your Cylinder Head ports because of casting imperfections. Yes. We all know, or some of us know that doing porting on a Cylinder Head or heads requires experience in such things. I am shocked at Kevs estimate for doing Port work ($400.00 to $800.00) ??? That seems like this to me:

 

Either the Machine Shop didn't really want to mess with it.

or

They were just trying to rip him off.

 

Bill

Yeah, it sounds like a bogus quote too. You know it will be $800+ with a quote like that. They might as well have said $800, plus or minus $600!

[Lizzord30]

The flow is pretty consistant, the atamized fuel is not is more the problem.

 

I had a friends who flow benched the stock intake and while I know its not a great method to find the flow as it doesn't have all 4 cyl running it did have a rather large difference of airflow for the middle 2 like 25%(may have been more was a long time ago) or more less flow for the middle 2. Air doesnt like to turn if it doesnt have to and its more straight to go from the tb to the cyl 1 and 4. That is why the middle 2 cyl are more likely to detonate(partly at lest other is they tend to be more warm) Their isnt atomization problems at 10+psi just less flow = less fuel for a carb/tbi setup.

 

I do think the Stock TBI has a atomization problem at lower boost all the way down to idle. This can be improved with using a spacer below the TB. Just like carb guys do with a carb intake. More length with the air at high velocity should help miss and fully atomize it. Not really any room under the hood of a starion for that tho... But I Just got done doing this on my montero (motor not in the truck yet) but I know another montero guy added a 1inc spacer(mine is 1.5) and he said made noticeable gains in the low end and even idol was more smooth.

[Shelby]

 

 

Not really... it's going to depend on what they are doing. This is also going on the assumption it's brand new fully appart ECT.

 

But easy 100 and hour to test on good flow bench.

Figure doing the valve areas is 300

Easy 100 an hour for the person doing the porting and between doing some porting and puting stuff back in it and then testing you got a few hours right there.

 

valve regrind and seating on a 4 cyl head should be no more then 1 hr labor ,,to be honest

[jszucs]

valve regrind and seating on a 4 cyl head should be no more then 1 hr labor ,,to be honest

 

I'm more thinking in line with a more race build then a simple rebuild.... you know where you would actuly think about porting it. It's allot of time and work to put larger valves, seats, out of better material, completely redo the head not just freshen up stock valves. And I would want a C&C done one not one done with stones. C&C done one's come out like mirror polished.

 

And would you also say that's true on a 16 valve 4 cyl? I doubt your going to get 16 ports done reassembled and tested on a flow bench, disassemble, do a bit more work, retest on a flow bench in an hour.

Edited May 2, 2013 by jszucs

[Lizzord30]

I'm more thinking in line with a more race build then a simple rebuild.... you know where you would actuly think about porting it. It's allot of time and work to put larger valves, seats, out of better material, completely redo the head not just freshen up stock valves. And I would want a C&C done one not one done with stones. C&C done one's come out like mirror polished.

 

And would you also say that's true on a 16 valve 4 cyl? I doubt your going to get 16 ports done reassembled and tested on a flow bench, disassemble, do a bit more work, retest on a flow bench in an hour.

 

Some people take 3hr to do a oil change also! lol

 

But actually I agree with you to do it very methodical will take some time, and if you do it fast probably not the same qulity. For someone thats done alot of heads for that one engine its alot easyer but for someone to first look at and dont really have a clue where the gains will be can deff take alot more time.

 

On A side note I wouldn't really want to run a head with sanificantly ground valve guides I dont like the chance of them loosening up(and yes I have seen it happen).

 

A running engine is more fun then a broken one even if its a slightly bit faster.

[Caliber308]

valve regrind and seating on a 4 cyl head should be no more then 1 hr labor ,,to be honest

 

Sounds about right. My machine shop charged me $40.00. And those were SS OS Valves.

 

Bill

[jszucs]

Some people take 3hr to do a oil change also! lol

 

But actually I agree with you to do it very methodical will take some time, and if you do it fast probably not the same qulity. For someone thats done alot of heads for that one engine its alot easyer but for someone to first look at and dont really have a clue where the gains will be can deff take alot more time.

 

On A side note I wouldn't really want to run a head with sanificantly ground valve guides I dont like the chance of them loosening up(and yes I have seen it happen).

 

A running engine is more fun then a broken one even if its a slightly bit faster.

 

Yes knowledge of the head and doing them day in and day out helps allot. Helps allot more when you have done it a few dozen times, have figured out the best flow you can get (by testing on proper flow bench) Then have that programed into a CNC machine that just does the port work at the push of a button to micoscopic precision. Your also going to pay for that though, becuase it cost a ton for the machine, it took a ton of trial and error, and you had to pay the dude to program the CNC machine too. But once done it's push button.

[Skullzaflare]

I had a friends who flow benched the stock intake and while I know its not a great method to find the flow as it doesn't have all 4 cyl running it did have a rather large difference of airflow for the middle 2 like 25%(may have been more was a long time ago) or more less flow for the middle 2. Air doesnt like to turn if it doesnt have to and its more straight to go from the tb to the cyl 1 and 4. That is why the middle 2 cyl are more likely to detonate(partly at lest other is they tend to be more warm) Their isnt atomization problems at 10+psi just less flow = less fuel for a carb/tbi setup.

 

I do think the Stock TBI has a atomization problem at lower boost all the way down to idle. This can be improved with using a spacer below the TB. Just like carb guys do with a carb intake. More length with the air at high velocity should help miss and fully atomize it. Not really any room under the hood of a starion for that tho... But I Just got done doing this on my montero (motor not in the truck yet) but I know another montero guy added a 1inc spacer(mine is 1.5) and he said made noticeable gains in the low end and even idol was more smooth.

if i recall correctly, you have it backwards. 1 and 4 get better airflow than 2 and 3, as air needs to 90 degree turn to go to 2 and 3. also, if i recall correctly, 2 and 3 run richer than 1 and 4 due to being closer to the injectors, and poor flow

[mstieg]

So much here that I ran out of positive "likes" for many of you by page 4, even though some of you disagree on a few things.

 

At $400-800 it's safe to say this is far too much to spend for porting, especially since the Kev said he's not looking for high end race type flow. For his setup he COULD go big, but that's not the goal. A cheaper mild port & cleanup WILL help as has been said. Mine was $260 including flow testing, port matching, and indexing the plugs.

 

KEV, you didn't list your IC and IC pipe sizing? At 65mm you should be at 2.5" piping to match. If smaller, that's your first restriction to take care of before head or cam work, which is last in line to match the rest.

[StarquestRescue]

 

if i recall correctly, you have it backwards. 1 and 4 get better airflow than 2 and 3, as air needs to 90 degree turn to go to 2 and 3. also, if i recall correctly, 2 and 3 run richer than 1 and 4 due to being closer to the injectors, and poor flow

At one time or another i have heard every possible cylinder or combination of cylinders named as being the lean one or ones.

 

What i have seen is # 3 tends to be the first to die. This is true whether it is a stock intake or mpi.

[Lizzord30]

Sorry that is what I ment the middle 2 are more lean, because of less airflow. and like SQR cyl3 seams to be a weak link most of the engines I have pulled plugs it looks the worst and usually the lowest compression. with 2 the second then 4 with 1 the most of course not always but most times. Could be from coolant and maybe why the FWD newer maganas had large coolant passage on both sides?

[Skullzaflare]

Sorry that is what I ment the middle 2 are more lean, because of less airflow. and like SQR cyl3 seams to be a weak link most of the engines I have pulled plugs it looks the worst and usually the lowest compression. with 2 the second then 4 with 1 the most of course not always but most times. Could be from coolant and maybe why the FWD newer maganas had large coolant passage on both sides?

More lean from less air?

You mean more rich from less air?

Center spark plugs are usually a little darker on my cars

[Lizzord30]

More lean from less air?

You mean more rich from less air?

Center spark plugs are usually a little darker on my cars

 

I think maybe it has poorer fuel atomization from the bend which means bigger droplets of fuel Giving some lean spots and also rich.

 

And the air takes the fuel with it. so less fuel can mean less air which is ok to make a match but it doesnt seam to work as good in practice as in theory.

Edited May 3, 2013 by Lizzord30

[Tim_C.]

That's what I mean about doing a bullhog above the seat. My machinist did it when he was set-up to grind the seats, so it didn't take much. He charged me $30 to open up the area above the seat, and to unshroud the seat in the chamber area.