fasterthanyou wrote:most of the cam specs i found were aftermarket, but i grabbed this from nasioc
Factory specs for 1997-1998 '4' cams (so not for HLA):
USDM EJ25D
Intake opens 6° BDTC
Intake closes 50° ABDC
Exhaust opens 54°/30° BBDC
Exhaust closes 10°/10° ATDC
Overlap 16°
JDM EJ20G
Intake opens 8° BDTC
Intake closes 52° ABDC
Exhaust opens 52° BBDC
Exhaust closes 8° ATDC
Overlap 16°
JDM EJ20K STI
Intake opens 10° BDTC
Intake closes 56° ABDC
Exhaust opens 56° BBDC
Exhaust closes 12° ATDC
Overlap 22°
i am just saying that i dont think it is neccessary to change cams. i do see the "obvious difference" in the cams. but you cant tell overlap from that pic! it only shows duration and lift.i dont know why you would hit a "wall" at 300 HP. that makes absolutely no sense, but i am sure it would not be from cams alone. if you had 8.5 to 1 on the stock motor it would be around 7 to 1 with 2.5d heads. you would need some serious custom pistons to run 8.5 to 1 with 25d heads.
engine management?
i dont see why everyone thinks that "overlap" is such a big deal. its hardly the issue on deciding between stock cams. besides turbo cams have more duration anyway. N/A cams are set up so they are open the same time but you really need aftermarket cams if you want big power. i am sticking with 25d cams because i dont want to pay a couple hundred for 20g cams or 1000 for aggressive cams. 25d cams work the best for my application. a stock 25d longblock(stock comp ratio of 10/1) with a turbo.
i agree you have to have the right combination of parts for each application, but there are so many factors that come into play
While some of your information is relevant, some is also mis-leading. It is obvious that your friend has not shared all of his knowledge with you.
When boosting and running turbo engines over-lap is everything. You run the correct overlap and you'll make huge power. You run too much over-lap and all your power goes out the exhaust... POOF!
The specs you "snagged" don't tell the whole story. Lift and duration do matter. Over-lap does matter. When you have too much overlap you will make less power. Not enough over-lap and you will build excessive cylinder pressure which can lead to blown head gaskets and other catastrophic failures.
And, 25D head suck until you port and polish, That is why everyone uses other heads in their place.
The best thing to do is run an adjustable cam gear. Unfortunately, no one makes them for Subaru's. That would make just about any cam feasible in a performance engine build!!