Need info about ported heads
06-20-2002, 08:35 PM
#1
Need info about ported heads
Whats up guys. I went by a local performance shop today that specialises in porting and polishing engines and engine parts. The shop was recommended to me from friends who have had good results there.
I spoke to the guy about having my heads ported, he said I would "probably" gain about 25-30 HP from this. Apparently he just bought some $27K machine that does all the porting, he said it does the porting with a great deal of precision and it results in a much nicer end result.
I asked how much and he said if I bring him the heads it would cost me about a grand. He said he would do it all for me(remove my heads) for about 2 grand. Now this is a bit expensive but I am thinking about doing it in a little bit.
Now for the questions
If the porting was done correctly how much HP do you think I could really get out of this?
If I wanted to remove my heads my self or with a experienced friend what all is involved? I have a 2002 nissan maxima shop manual on CD which may help. So to remove the heads, I have to take off the intake manifold, valve covers and the timing chain case and then some other little stuff? Is that on the right track or what? Please fill me in on this if you can.
Whats the down side of doing this? I would amagine worse fuel economy? Possible reliability issues? Please tell me what you think about possible reliability issues becuase that is my main concern.
Last and least, my exhaust note would probably be a little bit deaper right? And would my car be like a 3.7 L or something if I do this?
Thanks a ton for any help!
BTW I am definatly going to wait and see if the 350Z cams are better and maybe I will swap them in at the same time.
I spoke to the guy about having my heads ported, he said I would "probably" gain about 25-30 HP from this. Apparently he just bought some $27K machine that does all the porting, he said it does the porting with a great deal of precision and it results in a much nicer end result.
I asked how much and he said if I bring him the heads it would cost me about a grand. He said he would do it all for me(remove my heads) for about 2 grand. Now this is a bit expensive but I am thinking about doing it in a little bit.
Now for the questions
If the porting was done correctly how much HP do you think I could really get out of this?
If I wanted to remove my heads my self or with a experienced friend what all is involved? I have a 2002 nissan maxima shop manual on CD which may help. So to remove the heads, I have to take off the intake manifold, valve covers and the timing chain case and then some other little stuff? Is that on the right track or what? Please fill me in on this if you can.
Whats the down side of doing this? I would amagine worse fuel economy? Possible reliability issues? Please tell me what you think about possible reliability issues becuase that is my main concern.
Last and least, my exhaust note would probably be a little bit deaper right? And would my car be like a 3.7 L or something if I do this?
Thanks a ton for any help!
BTW I am definatly going to wait and see if the 350Z cams are better and maybe I will swap them in at the same time.
06-20-2002, 08:46 PM
#2
Senior Member
Join Date: Jun 2002
Posts: 704
It depends on how efficient the heads already are. I'd say 25-30 hp is probably way out there.
Nissan squeezed just about everything they could get out of that engine and there's probably not much more to be got out of it.
I mean this isnt some (relatively) inefficient Chevy 350 we're talking about here that you can mess around with in a machine shop and get massive gains. Considering how efficient your engine already is, I'd say 25-30 hp is unlikely.
Nissan squeezed just about everything they could get out of that engine and there's probably not much more to be got out of it.
I mean this isnt some (relatively) inefficient Chevy 350 we're talking about here that you can mess around with in a machine shop and get massive gains. Considering how efficient your engine already is, I'd say 25-30 hp is unlikely.
06-20-2002, 09:12 PM
#4
Ethan i hate to dissapoint you but I agree with these guys. Nissan does an excellent job when they design cylinder heads so there isn't any speakable gains to be had out of them. You would have to get some nasty racing cams, bigger valves, titanium valvetrain and get the heads hogged out for it to mean anything.
06-20-2002, 09:16 PM
#5
Hey thanks a lot for the help guys 
It's not much of a let down for me though becuase this was going to cost me a lot of time and money. I'm just happy I have you guys to talk to first! Who knows what I would do if I was on my own
Thanks again.
It's not much of a let down for me though becuase this was going to cost me a lot of time and money. I'm just happy I have you guys to talk to first! Who knows what I would do if I was on my own Thanks again.
06-20-2002, 11:08 PM
#6
Senior Member
Join Date: Aug 2000
Posts: 2,807
Re: Need info about ported heads
Those prices are on the high side. Ask if what type of valve job will be done and if they would recontour the combustion chamber. The headwork alone should only net around 5-13% gain at the wheels. So given a great job in porting expect about 8-16whp with more gain as the rpm increases. I should point out that it would be a waste to get headwork without cams. Since the engine is relatively new you can get the cams reground to different specs. I suggest a grind simular to the NISMO EURO cams for the VG30E. Or if your more hardcore go with the ISKY 270* grind for NA VG30E's. Cams + headwork would net at least 20-35whp over 5000rpm. I suggest getting heads from a VQ35 powered pathfinder to save downtime on your car. It is going to take at least 1 week for the headwork and probably 1-3 weeks for the cams. You can buy a VQ35DE for $2000 and after you swap heads you can sell the engine and make some money back. Besides headwork would help the SC make alot more power if you decide to go that route. Keep in mind that once you change the cams the ignition timing curve needs to be retuned for best performance. Since that can't be done with stock parts you are butted out 
. Actually outside of the variable IM on the VQ30 and VQ35's the VG30 and SR20 have the most *factory* cams based on duration.
. Actually outside of the variable IM on the VQ30 and VQ35's the VG30 and SR20 have the most *factory* cams based on duration.
Originally posted by emax95
Whats up guys. I went by a local performance shop today that specialises in porting and polishing engines and engine parts. The shop was recommended to me from friends who have had good results there.
I spoke to the guy about having my heads ported, he said I would "probably" gain about 25-30 HP from this. Apparently he just bought some $27K machine that does all the porting, he said it does the porting with a great deal of precision and it results in a much nicer end result.
I asked how much and he said if I bring him the heads it would cost me about a grand. He said he would do it all for me(remove my heads) for about 2 grand. Now this is a bit expensive but I am thinking about doing it in a little bit.
Now for the questions
If the porting was done correctly how much HP do you think I could really get out of this?
If I wanted to remove my heads my self or with a experienced friend what all is involved? I have a 2002 nissan maxima shop manual on CD which may help. So to remove the heads, I have to take off the intake manifold, valve covers and the timing chain case and then some other little stuff? Is that on the right track or what? Please fill me in on this if you can.
Whats the down side of doing this? I would amagine worse fuel economy? Possible reliability issues? Please tell me what you think about possible reliability issues becuase that is my main concern.
Last and least, my exhaust note would probably be a little bit deaper right? And would my car be like a 3.7 L or something if I do this?
Thanks a ton for any help!
BTW I am definatly going to wait and see if the 350Z cams are better and maybe I will swap them in at the same time.
Whats up guys. I went by a local performance shop today that specialises in porting and polishing engines and engine parts. The shop was recommended to me from friends who have had good results there.
I spoke to the guy about having my heads ported, he said I would "probably" gain about 25-30 HP from this. Apparently he just bought some $27K machine that does all the porting, he said it does the porting with a great deal of precision and it results in a much nicer end result.
I asked how much and he said if I bring him the heads it would cost me about a grand. He said he would do it all for me(remove my heads) for about 2 grand. Now this is a bit expensive but I am thinking about doing it in a little bit.
Now for the questions
If the porting was done correctly how much HP do you think I could really get out of this?
If I wanted to remove my heads my self or with a experienced friend what all is involved? I have a 2002 nissan maxima shop manual on CD which may help. So to remove the heads, I have to take off the intake manifold, valve covers and the timing chain case and then some other little stuff? Is that on the right track or what? Please fill me in on this if you can.
Whats the down side of doing this? I would amagine worse fuel economy? Possible reliability issues? Please tell me what you think about possible reliability issues becuase that is my main concern.
Last and least, my exhaust note would probably be a little bit deaper right? And would my car be like a 3.7 L or something if I do this?
Thanks a ton for any help!
BTW I am definatly going to wait and see if the 350Z cams are better and maybe I will swap them in at the same time.
06-21-2002, 12:37 AM
#7
Senior Member
Join Date: Jan 2001
Posts: 1,816
It's a lot of expense but if you're willing to get 350z cams in the future it might be worth it. I think our vq35de has a bit more to squeeze out of it ala 350z.
You will not however increase your displacement whatsoever. Most of your gains will occur higher into the RPM range where we need em anyway. Displacement increase occurs when the bore and/or stroke of the actual combustion volume is increased.
I would talk to the guy more and ask him his rationale on how he believes you could gain as much whp as he's claiming.
You will not however increase your displacement whatsoever. Most of your gains will occur higher into the RPM range where we need em anyway. Displacement increase occurs when the bore and/or stroke of the actual combustion volume is increased.
I would talk to the guy more and ask him his rationale on how he believes you could gain as much whp as he's claiming.
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