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Old 09-05-2010, 02:04 AM   #1
GundamFan
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Default Which heads for my 450whp 8500rpm 2.5 build? Block is done!

I just got done building an 05 sti 2.5 SB w forged pistons an rods. Which year/model sti heads are the best for high revving as in safety/reliability. Ill be using gsc s2 cams and manly valve springs/ti retainers in whatever heads are good. I read something about shim under bucket heads revving higher but i dont know what that means

budget is $600-$800 but i dont mind spending less ill be using a gt35r sized turbo (ihi rx6r), goal as mentioned is 450whp and 8500rpm i prefer to use stock valves and not have to port the head but i am open to all sugestions so long as there is an explanation to go w your recomendation, thanks!!
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Old 09-05-2010, 10:31 AM   #2
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JDM v7 or v8 Big port heads. get them CNC'ed to match the 2.5 SB. You should be fine.

Didn't see your budget, but a member got these heads on ebay at a bargain.

Last edited by StraightBoosted; 09-05-2010 at 10:38 AM.
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Old 09-05-2010, 11:03 AM   #3
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Quote:
Originally Posted by StraightBoosted View Post
JDM v7 or v8 Big port heads. get them CNC'ed to match the 2.5 SB. You should be fine.

Didn't see your budget, but a member got these heads on ebay at a bargain.
Would the stock Spec C cams cope at this level?
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Old 09-05-2010, 03:46 PM   #4
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Would the stock Spec C cams cope at this level?

They should be fine. To further clarify this, I would shoot soobaviator a PM. Or he would chime in when he sees this.
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Old 09-05-2010, 07:11 PM   #5
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Cool, ill pm him if he dont comment...
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Old 09-06-2010, 01:45 AM   #6
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The cheapest method would be to just get any old set of STi heads, get OS valves and a nice valve job, and use the rest of the parts you mentioned. That should run about $1k if you already have the valves/springs/rets/cams.
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Old 09-06-2010, 04:38 AM   #7
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The cheapest method would be to just get any old set of STi heads, get OS valves and a nice valve job, and use the rest of the parts you mentioned. That should run about $1k if you already have the valves/springs/rets/cams.
Whats a good and reasonably priced place to have heads ported? Im not cheap ive just already spent a good amount.
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Old 09-06-2010, 04:45 AM   #8
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Quote:
Originally Posted by GundamFan View Post
Whats a good and reasonably priced place to have heads ported? Im not cheap ive just already spent a good amount.
That will probably be the most exspensive part of your head build.
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Old 09-06-2010, 06:04 AM   #9
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That will probably be the most exspensive part of your head build.
I doubt that, my turbo kit cost $5200, the turbo i plan on running alone is $2700, i have $3000 in the shortblock, if porting heads cost that much im gonna friggin shoot myself!

Do i even need poted heads for my goal?
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Old 09-06-2010, 06:16 AM   #10
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Originally Posted by GundamFan View Post
I doubt that, my turbo kit cost $5200, the turbo i plan on running alone is $2700, i have $3000 in the shortblock, if porting heads cost that much im gonna friggin shoot myself!

Do i even need poted heads for my goal?
I was talking about just the heads. not the rest of your setup.
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Old 09-06-2010, 06:43 AM   #11
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I was talking about just the heads. not the rest of your setup.
Phew thank god, i was about to crap my pants lol.
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Old 09-06-2010, 01:37 PM   #12
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Your BOV sounds lame
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Quote:
Originally Posted by GundamFan View Post
I doubt that, my turbo kit cost $5200, the turbo i plan on running alone is $2700, i have $3000 in the shortblock, if porting heads cost that much im gonna friggin shoot myself!

Do i even need poted heads for my goal?
None of those prices make any sense to me.

Since you are in S. Cal. there should be plenty of places around where you could get the work done locally. I would ask in your hometown forum.

Actual porting isn't all that required (ex.: http://forums.nasioc.com/forums/show....php?t=2034903). I would just get OS valves, a valve job, and have the castings cleaned up. That will net you 90% of the gains to be had.
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Old 09-06-2010, 05:00 PM   #13
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None of those prices make any sense to me.

Since you are in S. Cal. there should be plenty of places around where you could get the work done locally. I would ask in your hometown forum.

Actual porting isn't all that required (ex.: http://forums.nasioc.com/forums/show....php?t=2034903). I would just get OS valves, a valve job, and have the castings cleaned up. That will net you 90% of the gains to be had.
Look up the PE RX6R turbo kit, its expensive, and building a sb w rods too, new seals, new crank, new oil pump, forged pistons, new bearings, labor and machine work it comes out to a lot thanks for the advise on os valves, will consider for sure!
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Old 09-06-2010, 06:56 PM   #14
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Your BOV sounds lame
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No, I meant that turbo costs wayyyy too much and that block costs notably less than most I've seen. Get a P&L 35R kit and get it converted to an HTA82, or 86. This stuff isn't cheap, but there is no need to throw money away.
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Old 09-06-2010, 07:46 PM   #15
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No, I meant that turbo costs wayyyy too much and that block costs notably less than most I've seen. Get a P&L 35R kit and get it converted to an HTA82, or 86. This stuff isn't cheap, but there is no need to throw money away.
Oh, well its a good turbo and i already have it, this is literally one of the best turbos in the world, do some research and youll see, as far as the block goes my friend owns a shop so all the parts i got at cost and my machine shop is charging me $1100. I save money in one spot then i spend it somewhere else, this setup will put an hta turbo to shame with spool and power, its a titanium shaft sealed ball bearing turbo that can be run well above 30psi without tapering off and can be run without a blow off valve w no issues as it was originally designed for the twin turbo Formula 1 cars that ran 80psi and WRC but now most teams use the TR30R. This turbo is the same size as a 35r and weighs half as much, its a pretty neat setup the only other turbos i would consider are Comp and Garrett.

http://www.rhdjapan.com/power-enterp...er-a-r18-54958

Last edited by GundamFan; 09-06-2010 at 07:52 PM.
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Old 09-11-2010, 08:23 AM   #16
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Ttt for more opinions...
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Old 09-11-2010, 08:34 AM   #17
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So u r buying a $2700 turbo to make 450hp I think u got your answer already as a stock head is more than capable of making your power goals.
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Old 09-11-2010, 07:13 PM   #18
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As CKxx said the cheapest is going to be STI heads + oversized valves. However you are leaving a lot on the table with OEM STI ports.

With STI heads the turbo needs more lift in the valves and you'll be well out of the power band at 8.5K RPM.

The JDM big port heads are the best solution off the shelf but outside of your budget. You've spent a lot of money on the other parts of the motor and $800 is not enough to make adequate 450WHP heads IMO.

Did you do anything with the bottom end to support 8,500 RPM? Balancing? Oil relieving? Crank mods?


-soobaviator

Last edited by soobaviator; 09-11-2010 at 07:29 PM.
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Old 09-11-2010, 08:29 PM   #19
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So u r buying a $2700 turbo to make 450hp I think u got your answer already as a stock head is more than capable of making your power goals.
some people would say building an sti is overpriced as u could build a $3500 civic to be just as fast for half price or less but nobody is nocking that, we all have a choice to spend money the way we want, ive been doing this car hobby for 11 years, ive learned to save and buy the parts i want, it makes me happy you dont have to agree but i dont need your attitude bro.

Quote:
Originally Posted by soobaviator View Post
As CKxx said the cheapest is going to be STI heads + oversized valves. However you are leaving a lot on the table with OEM STI ports.

With STI heads the turbo needs more lift in the valves and you'll be well out of the power band at 8.5K RPM.

The JDM big port heads are the best solution off the shelf but outside of your budget. You've spent a lot of money on the other parts of the motor and $800 is not enough to make adequate 450WHP heads IMO.

Did you do anything with the bottom end to support 8,500 RPM? Balancing? Oil relieving? Crank mods?


-soobaviator
you think even with the gsc s2 cams i wont make power that high? My engine builder did certain things to ensure high rpm use of the block, one of my friends used the same builder w great success and revs to 8000rpm all the time, has 10k miles so far with zero oil consumption. i dont know wat he does but it works.

I will spend more if i have to, i just want increasing power at least to 8000rpm. Im used to my Honda that revs to 9k with factory head/block so im a bit spoiled, and if anybody wants to clown my Honda it makes more power per psi, revs higher, spools faster and is a measly 1.6 so plz save it.
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Old 09-12-2010, 10:37 AM   #20
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Revving to 8K and making peak power at 8K are two entirely different things. Unless you are going to invest in fully built ported heads you won't have peak power at 8K. It's easy enough to set the rev limiter for 8500 and go for it but the setups you're talking about peak power is going to be 6.5-7K and fall off from there to one degree or another.

GSC stage 2 cams are nothing special actually. To overcome the 2.5l mechanical characteristics that limit power at high RPM you need bigger intake ports and a combination of increased lift and duration. Duration and porting would be key to getting the peaky power band you are looking for.
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Old 09-12-2010, 04:10 PM   #21
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I don't understand why you want the IHI Rx6. Do you just have to have an IHI turbo?
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Old 09-13-2010, 01:13 AM   #22
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I don't understand why you want the IHI Rx6. Do you just have to have an IHI turbo?
I already own it, i dont understand why u care so much, some people spend $1300 for carillo rods when eagles will be just as good for there power goal but nobody gives them a hard time. Its not about brand, i have a garrett 3076 on my honda and plan to use a comp turbo on my ndxt build, i use wat i know works i have seen this turbo outperform a 35r so to me its worth it, plus like i said it was used in f1 and wrc, that says something.

My turbo-$2800
ATP stock location 35r plus external gate-$2250

not that big of a difference if u think about it, plus i got a good deal on it plus extras, i spent some coin but got an amazing deal, now do u have a head sugestion for me or not bro?
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Old 09-13-2010, 05:41 AM   #23
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The people here are probably just surprised that your turbo cost 4x as much as you're willing to spend on your heads. Most people spend more on their heads than their turbos. Why? The cheapest way to reach a goal is to focus spending on modifications that eliminate the greatest number of limiting factors/power robbers per dollar. If you spent $1500 on your turbo instead of $2800 you'd have $2000 to spend on your head build. In the end you'd have almost definitely made more power.

With that being said, let me get this straight; you ALREADY OWN cams, springs and retainers, but you don't have head castings. Your $600-800 budget is for the head castings and anything else, correct? If so, you don't have enough. At minimum you'll need to buy USDM sti head castings, redo valve lash (either grind down the valves or buy new buckets), and get a light port (I recommend outfront motorsports). $2000 probably would have been enough.
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Old 09-13-2010, 09:37 AM   #24
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Quote:
Originally Posted by GundamFan View Post
some people would say building an sti is overpriced as u could build a $3500 civic to be just as fast for half price or less but nobody is nocking that, we all have a choice to spend money the way we want, ive been doing this car hobby for 11 years, ive learned to save and buy the parts i want, it makes me happy you dont have to agree but i dont need your attitude bro.
2010-11= 1999........What year is your car?

I will spend more if i have to, i just want increasing power at least to 8000rpm. Im used to my Honda that revs to 9k with factory head/block so im a bit spoiled, and if anybody wants to clown my Honda it makes more power per psi, revs higher, spools faster and is a measly 1.6 so plz save it.
Quote:
Originally Posted by GundamFan View Post
I already own it, i dont understand why u care so much, some people spend $1300 for carillo rods when eagles will be just as good for there power goal but nobody gives them a hard time. Its not about brand, i have a garrett 3076 on my honda and plan to use a comp turbo on my ndxt build, i use wat i know works i have seen this turbo outperform a 35r so to me its worth it, plus like i said it was used in f1 and wrc, that says something.

My turbo-$2800
ATP stock location 35r plus external gate-$2250

not that big of a difference if u think about it, plus i got a good deal on it plus extras, i spent some coin but got an amazing deal, now do u have a head sugestion for me or not bro?
Attitude, attitude, attitude
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Old 09-13-2010, 05:27 PM   #25
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Originally Posted by WReXd View Post
The people here are probably just surprised that your turbo cost 4x as much as you're willing to spend on your heads. Most people spend more on their heads than their turbos. Why? The cheapest way to reach a goal is to focus spending on modifications that eliminate the greatest number of limiting factors/power robbers per dollar. If you spent $1500 on your turbo instead of $2800 you'd have $2000 to spend on your head build. In the end you'd have almost definitely made more power.

With that being said, let me get this straight; you ALREADY OWN cams, springs and retainers, but you don't have head castings. Your $600-800 budget is for the head castings and anything else, correct? If so, you don't have enough. At minimum you'll need to buy USDM sti head castings, redo valve lash (either grind down the valves or buy new buckets), and get a light port (I recommend outfront motorsports). $2000 probably would have been enough.
ive said im willing to spend more if needed
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[/b]


Attitude, attitude, attitude
my subaru is my sixth car im 27 if that answers your question? 11-27=16, whats so hard to understand? Dude, just leave it if u dont want to help.
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