Head Work

[Melanism]

Okay...I called a place the other day that does head work (port and polish) and the rep explained to me all that would be done and how long also an estimate price. The rep said I can expect to gain 25-30 horsepower gain. Is this realistic? Would anyone recommend doing this or not? I don't wanna go turbo, cuz to me it just doesnt make sense on our cars. Seems as if our cars are a little to iffy to take boost for long periods of time. Thats just me...maybe I'm wrong. Anyway. What are all your opinions on getting the work done to an MP3?

 

[mp5jeff]

i doubt that much hp just from port/polish, also u said you dont want turbo cuz they are iffy, if you start doing engine work ur cars engine life will go down also

 

[KYMP5]

if your going to build a motor worht a s*** ,power wise, it has to be done. as far as the umbers go, that sounds about right. the head is the final step in the whole intake/exhaust setup.
for maximum power you have to have max air flow.
1st-air intake
2nd-exhaust
3rd-header
4th-high flow cat
All of the above still work fine but the you still have restriction in the head.
5th-headwork

 

[changedman]

whats it run? im interested now in doing it

 

[KYMP5]

im definitely having it done on the motor im building now. Headwork on a n/a motor is supposed to be one of the most beneficial gains you can get.

 

[changedman]

costs, details, it sounds interesting

 

[Kooldino]

How much will it run? I somehow doubt you'll get that much power out of it, but, then again, I hope I'm wrong. Be a pioneer...go ahead with it. Just dyno before and after.

PS-Turbo is fine as long as you do it right.

 

[Melanism]

Price

Well thanks for all of your input. Seems like a split crowd so far as far as expected HP gains. I was quoted $725 for valve work, port and polish, and cams set in. I don't know whats high and what's low, so I'm going to contact another shop my friend told me aout to see what i'm working with. I will post details as soon as I find out.

 

[MikeBlueP5]

i used to do this for a living, that price, im gonna say includes a valve job (complete rebuild), at least a 3 angle job on the seats if not 5. New valve stem seals, and the port and polish job while its apart. And as for the cams reset, all the do is put them back in and readjust the lash adjustment. You will have to pull the cams to put the head back on the car i believe. And the only reason they readjust the cams is because when they do the valve job they cut the seats down to make a fresh seating surface, when the do this it makes the stem too long. They have to cut the stem and therefore reshim the valves. Its really easy and i would say that the price for a rebuild on the head alone would run between 250-325. Plus an additional 350 or so for the port job. Its alot of work with a die grinder is all it is.

 

[BlueMP5Dave]

Mikeblue is it worth it in your opinion if you were to remain NA.

 

[changedman]

what ballpark HP gains we talking?

 

[MikeBlueP5]

i would say if you plan on going N/A and you want power, take them the head, the intake and a exhaust mani gasket, tell them to port the head, the intake manifold, and port match the head. Then you will really feel the difference. I would say go for it. Another thing i would do while the head is off is get the high compression pistons from the jspec, and also tell them to mill a few thousands off the head to increase compression. thatll get you even more gains. but i would shop around, also look out for what shops have the best rep. Ask around. Local racers at tracks and s*** ya know. I would do it if i were to rebuild my engine. would i tear into it now? um probably not.

 

[twilightprotege]

30whp is possible with a good porting job on the head...if the rest of your system is happy (ie cams, exhaust, intake).

if you like, you can wait until i get my head work done this time next month. i've just had cams grinded to pretty hot specs - i'm going to do a dyno with just cams. then this time next month the head will be off getting ported. i'll then dyno again. keep an eye on this thread : http://www.msprotege.com/vbb225/showthread.php?s=&threadid=29631

 

[Kooldino]

twilightprotege - i can't WAIT to see what you find!

everyone - what's a 3/5 angle valve job all about?

MikeBlueP5 - wouldn't it just be easier for him to get the head milled to raise the compression instead of doing that AND getting HC pistons?

 

[mp3moose]

I have HC pistons and am considering cams, head work, valve job. But I need cost and hp details.
Moose

 

[MikeBlueP5]

kool-it might be possible to mill the head and get the amount of compression the pistons give, then again maybe not. I would have to pull the aera book and check the specs on what the minumum thickness of the head could be, then do the math to figure out what the compression would be after taking off X thousands of an inch.

I just mentioned the pistons because they would be super easy to put in while the head is off and it would give him something to do while the head is at the machine shop.

 

[mp3moose]

Woah, my pistons took a weekend. I know some of that time was pulling the head, but these pistons aren't friendly. I shattered one in attempts to take it out. I had to pull the engine out completely and drive it to a shop that had machinery to get piston ring off.
Just an FYI

Moose

 

[MikeBlueP5]

i dont see how you shattered it? And as for the rings, i would hone the bores and install new ones. Also i think our pistons have to be pressed on the rod, if i remember linux correctly, that would require a machine shop with the proper equipment. As for removing them all you should have to do is remove the head, drop the oil pan, unbolt the rods and push it out the top.

 

[twilightprotege]

kooldino - 3 angle and 5 angle valve seat jobs is pretty simple to explain. a 3 angle job looks like
|
\_

i know that's very bad, but that's the idea...anyway, a 5 angle is just the same but a not as steep \ after the _ and a steeper \ just before the |

the advantages? 5 angle allows the air to flow just that tiny bit smoother into the combusion chamber. under 500hp there is little to no use for using 5 angle. 3 angle does the job just fine. does that explain it ok?

all - i wouldnt recommend milling the head much - it can alter the cooling jacket holes too much....but a few mm shouldnt hurt in any way...but having said that, i have no idea how much 1mm will increase the compression by.....
also changing the pistons is a good day's work atleast. if you really want to do that, you might as well fix up everything while you're at it - ie forged rods, knife edge the crank, have everything balanced etc....

edit : fixed up the \_ etc piccy

 

[twilightprotege]

ps - i cant wait to see what improvement porting the head gives as well!!!! i'm sure there is a lot to be gained....