Cams on an STI with stock heads ; Thoughts and Perspectives?

syoung298 · 11-12-2007, 04:10 PM

Does anyone have eny experience with cams on stock sti heads? I'm considering purchasing a cosworth head package, but in the event the heads remain stock, I was wondering if anyone had real world perspectives to share.

For context; the car is an 05 sti with 20K miles, with previously an UR GT35, Hydra, and other relevant mods. The 05 motor will be coming out in 2 weeks (bad rings from detonation with the gt35) for an 07 sti motor with 1200 miles including trans and drivetrain (tired of the short 3rd and 4th in the 05). I was planning on building the block, but with numerous horror stories, I would prefer to keep it stock at this time. More than likely, I'll install a full race header, gt52, and Hydra 2.6 once the motor is swapped (end of november)

having said that any thoughts or experiences with a stock STI heads and cams; and if so which cams? I was considering the cosworth 262? or 274?.

Thanks in advance.

Flycaster · 11-12-2007, 04:19 PM

If you're going to push it hard enough to use the cams, you really ought to at least put in a set of forged pistons while you have the motor out. As for the rest, I'll leave it to others who've done it. Go forged, amigo, and mitigate the risk of breaking a piston.

mllrsti · 11-12-2007, 06:30 PM

I hope you're not considering using the stock valvetrain. BTW, Cosworth has 278/274 AVCS cams available. The price/power ratio for their head package to me isn't the best bang for the buck, the turbo you use has a lot to do with it.

syoung298 · 11-12-2007, 06:38 PM

Quote:

Originally Posted by mllrsti

I hope you're not considering using the stock valvetrain. BTW, Cosworth has 278/274 AVCS cams available. The price/power ratio for their head package to me isn't the best bang for the buck, the turbo you use has a lot to do with it.

The more I think about it; the more I'm leaning towards a stock shortblock with cosworth heads and cams.. Since i don't plan on exceeding 400whp, I hope this won't be an issue. My primary concern is reliability, and I'm not completely convinced that any aftermarket engine builder can gaurantee a motor that is as reliable, albeit more sout, than a stock Subaru shortblock.. perhaps axis or cosworth...

jays05 · 11-12-2007, 07:51 PM

A $5k head/cam package on a $1500 shortblock with 400whp goals just does not make sense.

Other than that... Flycaster said everything!

STimo · 11-12-2007, 10:42 PM

Quote:

Originally Posted by syoung298

The more I think about it; the more I'm leaning towards a stock shortblock with cosworth heads and cams.. Since i don't plan on exceeding 400whp, I hope this won't be an issue. My primary concern is reliability, and I'm not completely convinced that any aftermarket engine builder can gaurantee a motor that is as reliable, albeit more sout, than a stock Subaru shortblock.. perhaps axis or cosworth...

I dont think that's a very good idea at all.. The stock heads/cams are plenty for 400whp, the weak link is the pistons.. If i were you i would drop in some forged pistons and call it a day, hell i've been running my 30R @ 22psi for 17K miles now on the stock longblock without any issues, and im making a bit under 400whp so if you want reliability then forged pistons is the way to go.. I dunno why you are so worried about the heads if you dont plan on exceeding 400whp, people have pushed 500+whp out of the stock heads/cams and they flow fine..

ninjaboy76 · 11-13-2007, 12:05 AM

Quote:

Originally Posted by STimo

I dont think that's a very good idea at all.. The stock heads/cams are plenty for 400whp, the weak link is the pistons.. If i were you i would drop in some forged pistons and call it a day, hell i've been running my 30R @ 22psi for 17K miles now on the stock longblock without any issues, and im making a bit under 400whp so if you want reliability then forged pistons is the way to go.. I dunno why you are so worried about the heads if you dont plan on exceeding 400whp, people have pushed 500+whp out of the stock heads/cams and they flow fine..

^ This right here pretty much says it all. Why mess with head work when the STI weak link is pistons and rings. Plus I hope you get a better tune or have learned what caused the first motor to take a dump on you. Going with a smaller turbo and sticking around the 400whp mark doesn't guarantee that you'll be reliable. In fact your more liable to be doing this all over again in the near future at the 400whp mark. There have been plenty of STIs that have gone tits up with the stock turbo and a bad protune. It doesn't take much to destroy an engine.

Tortfeasor STi · 11-13-2007, 07:05 AM

Quote:

Originally Posted by ninjaboy76

It doesn't take much to destroy an engine.

What he means is, a bad tune on an otherwise stock car will grenade an engine.

As for building up an engine, the most important part of engine building is making sure all the parts match each other. If you run a GT35R with a cosworth head and cam package on a stock long block you are asking for trouble. The reason is that the stock pistons and rings were designed to last 150,000 miles at stock 220-240 whp range. When you slap on racing heads, racing cams and a huge turbo you are going to be making close to double this amount of power. All this extra air and fuel create cylinder pressures that the stock bottom end is simply not equipped to deal with. If you are going through the hassle of rebuilding the engine, do it right the first time and put in a forged rotating assembly. Otherwise you are likely to pop this new engine in short order and be back at the drawing board.

Flycaster · 11-13-2007, 07:21 AM

Quote:

Originally Posted by Tortfeasor STi

...do it right the first time and put in a forged rotating assembly...

And, the only parts not forged in the stock rotating assembly are the pistons.

***Neanderthal Racing*** · 03-02-2008, 06:15 PM

i recommend upgrading your valve springs and retainers if you have the heads off and get the opportunity. also, it's very manly to do a lot of headwork until you realize what that dramatic shift to the right will do for your fun factor on the street.

boostedrex05 · 04-21-2008, 05:24 PM

buy a cosworth block for 5400 and call it a day.. maybe up grade the valve springs retainers and cam's

subydude1974 · 05-02-2008, 10:01 AM

Basically the only benefits of the Cosworth Heads and Cams are if you are looking for more TOP End Horsepower. The Intake Valves flow 15% more and Exhaust Valves flow 31% more than stock which allows more fuel and air for High Horsepower applications.

mofoSTI · 05-02-2008, 10:16 AM

Tomei has some cams tuned for the jdm big port heads (07 08 ports are bigger than prior years) with no porting. If I were you I would do a cobb short block with the forged pistons and the tomei 252 cams.

Md05STI · 05-06-2008, 10:20 PM

I have completely stock heads with Kelford 274's and have had no issues at all. The car made just shy of 550whp and rev's to 8k. To make use of the cams I'd say you would need a built bottom end like others have already said.

boostedrex05 · 05-08-2008, 11:20 PM

Quote:

Originally Posted by Md05STI

I have completely stock heads with Kelford 274's and have had no issues at all. The car made just shy of 550whp and rev's to 8k. To make use of the cams I'd say you would need a built bottom end like others have already said.

what kinda dyno did you make shy of 550whp on? I made 512 on a dyno dynamics stock engine stock heads and cam's 0 correction so it's really like 10-20% more from what i herd.

11-12-2007, 04:10 PM	#1
syoung298 STI Driver Car: 05 sti Fav Mod: APS tsr70 Location: Virginia Posts: 244 Join Date: Apr 2005 Trader Rating: (0)	Cams on an STI with stock heads ; Thoughts and Perspectives? Does anyone have eny experience with cams on stock sti heads? I'm considering purchasing a cosworth head package, but in the event the heads remain stock, I was wondering if anyone had real world perspectives to share. For context; the car is an 05 sti with 20K miles, with previously an UR GT35, Hydra, and other relevant mods. The 05 motor will be coming out in 2 weeks (bad rings from detonation with the gt35) for an 07 sti motor with 1200 miles including trans and drivetrain (tired of the short 3rd and 4th in the 05). I was planning on building the block, but with numerous horror stories, I would prefer to keep it stock at this time. More than likely, I'll install a full race header, gt52, and Hydra 2.6 once the motor is swapped (end of november) having said that any thoughts or experiences with a stock STI heads and cams; and if so which cams? I was considering the cosworth 262? or 274?. Thanks in advance. This ad is not endorsed by this member. Please register or login to hide this ad.

11-12-2007, 04:19 PM	#2
Flycaster S204 Racer Posts: 2,953 Join Date: Apr 2004 Trader Rating: (0)	Re: Cams on an STI with stock heads ; Thoughts and Perspectives? If you're going to push it hard enough to use the cams, you really ought to at least put in a set of forged pistons while you have the motor out. As for the rest, I'll leave it to others who've done it. Go forged, amigo, and mitigate the risk of breaking a piston.

11-12-2007, 06:30 PM	#3
mllrsti Professional STI Racer Posts: 696 Join Date: Dec 2004 Trader Rating: (0)	Re: Cams on an STI with stock heads ; Thoughts and Perspectives? I hope you're not considering using the stock valvetrain. BTW, Cosworth has 278/274 AVCS cams available. The price/power ratio for their head package to me isn't the best bang for the buck, the turbo you use has a lot to do with it.

11-12-2007, 07:51 PM	#5
jays05 Spec C Club Fav Mod: when it's not blown up Location: Upstate NY Posts: 1,474 Join Date: Nov 2004 Trader Rating: (0)	Re: Cams on an STI with stock heads ; Thoughts and Perspectives? A $5k head/cam package on a $1500 shortblock with 400whp goals just does not make sense. Other than that... Flycaster said everything!

03-02-2008, 06:15 PM	#10
*Neanderthal Racing* Support Our Sponsors Car: CUTN EDG project Fav Mod: $20. mudflaps from auto zone Location: my cave Posts: 5,729 Join Date: Dec 2003 Trader Rating: (1)	Re: Cams on an STI with stock heads ; Thoughts and Perspectives? i recommend upgrading your valve springs and retainers if you have the heads off and get the opportunity. also, it's very manly to do a lot of headwork until you realize what that dramatic shift to the right will do for your fun factor on the street.

04-21-2008, 05:24 PM	#11
boostedrex05 Spec C Club Car: 512whp STi Fav Mod: Junior Tuned Location: N.Y Posts: 1,182 Join Date: Dec 2005 Trader Rating: (1)	Re: Cams on an STI with stock heads ; Thoughts and Perspectives? buy a cosworth block for 5400 and call it a day.. maybe up grade the valve springs retainers and cam's

05-02-2008, 10:01 AM	#12
subydude1974 Amateur STI Driver Car: 07 OBP STi Fav Mod: All Location: Jacksonville, FL Posts: 48 Join Date: Dec 2007 Trader Rating: (0)	Re: Cams on an STI with stock heads ; Thoughts and Perspectives? Basically the only benefits of the Cosworth Heads and Cams are if you are looking for more TOP End Horsepower. The Intake Valves flow 15% more and Exhaust Valves flow 31% more than stock which allows more fuel and air for High Horsepower applications.

05-02-2008, 10:16 AM	#13
mofoSTI Spec C Club Car: 08 STI,sr20det 510 Fav Mod: boob job for wife Location: springtuckey, OR Posts: 2,165 Join Date: Sep 2004 Trader Rating: (0)	Re: Cams on an STI with stock heads ; Thoughts and Perspectives? Tomei has some cams tuned for the jdm big port heads (07 08 ports are bigger than prior years) with no porting. If I were you I would do a cobb short block with the forged pistons and the tomei 252 cams.

05-06-2008, 10:20 PM	#14
Md05STI STI Driver Car: 05 CGM STI Fav Mod: Element Tuning Location: MD Posts: 201 Join Date: Nov 2004 Trader Rating: (0)	Re: Cams on an STI with stock heads ; Thoughts and Perspectives? I have completely stock heads with Kelford 274's and have had no issues at all. The car made just shy of 550whp and rev's to 8k. To make use of the cams I'd say you would need a built bottom end like others have already said.