Cam Lobes

[Phast SVX]

wow, guys let the cams be. that is NOT where the power is to be had. not for the money atleast!

[SVXRide]

Originally Posted by Phast SVX

wow, guys let the cams be. that is NOT where the power is to be had. not for the money atleast!

Phil,
You might just be surprised....there appears to be some NA "headroom" to be had (i.e., the Subaru engineers might just have been a little conservative )
-Bill

[Phast SVX]

sorry guys, was drunk last night when i posted that, dont even remember doing it

[dynomatt]

Phil...guess again.

Bill, what's that graph? Apart from big!

Matt

[SVXRide]

Matt,
Graphic should be a little smaller now
Let's just say that I'm working with someone down in your part of the world on what a "streetable" NA SVX might be capable of
-Bill

[Phast SVX]

Originally Posted by SVXRide

Matt,
Graphic should be a little smaller now
Let's just say that I'm working with someone down in your part of the world on what a "streetable" NA SVX might be capable of
-Bill

definetly cool Do you have plans to get around the 6500rpm shift by the tcu? Ill pm you back later today, just quickyl poking in at work here
phil

[dynomatt]

Not sure whether it's worth posting this in the other thread as well...or whether that's gotten too convoluted.

Anyhoo. Here's some random learnings.

Valve spring coil bind occurs at or about 9mm (no news there).

Using only a regrind profile (ie no welding as well), the most lift you'll get out of the cam is 9.6mm. This is a limitation of the cam journal size.

WRX valves are the same diameter (36mm/32mm) but have 104mm stems rather than our piddly 90mm.

Hydraulic buckets can have their centre bored out to make them solid. WRX buckets are solid and are also 33mm so "should fit"*

In theory* a complete WRX valve, spring, retainer and bucket should go in the same slot as the EG33...thereby rewarding us with more lift potential...for a reasonably low cost.

* - this will be tested when I get to have a play with some WRX valves in the next few days.

Matt

[SVXRide]

Originally Posted by dynomatt

Not sure whether it's worth posting this in the other thread as well...or whether that's gotten too convoluted.

Anyhoo. Here's some random learnings.

Valve spring coil bind occurs at or about 9mm (no news there).

Using only a regrind profile (ie no welding as well), the most lift you'll get out of the cam is 9.6mm. This is a limitation of the cam journal size.

WRX valves are the same diameter (36mm/32mm) but have 104mm stems rather than our piddly 90mm.

Hydraulic buckets can have their centre bored out to make them solid. WRX buckets are solid and are also 33mm so "should fit"*

In theory* a complete WRX valve, spring, retainer and bucket should go in the same slot as the EG33...thereby rewarding us with more lift potential...for a reasonably low cost.

* - this will be tested when I get to have a play with some WRX valves in the next few days.

Matt

Matt,
Good stuff! It would be nice if the springs work, as we're looking for springs that are ~10% stiffer to use with the new intakes and exhaust cams. Can you do a "stock-to-stock" spring stiffness comparison?
-Bill

[Trevor]

Matt,

You are now on my wavelength as a result of researching what is available, exists and what is practical. If you modify the lifters to solid, can you gain vital spring space ? Grinding/reducing the back of the cams will assist in this area.

Good thinking, Trevor.

[NeedForSpeed]

Matt,

Thanks for posting this info in this thread.

To add further, and please confirm if you can, I'm told that the hydraulic bucket can 'pump up' approximately .075" more [Harvey posted .75mm plus .50mm? in this thread, about .030"-.050"]. If true, the cam base can be reduced by that same amount adding .075" lift to the cams. .280"/.311" lift plus .075" gives .355"/.386" or 9mm/9.8mm lift without welding. [Matt, did you mean 9.6mm lift on the intake lobe?]

By not welding, most of the cost involved in modifying our cams is saved. If one is comfortable with a reduced cam base and one installs a valve spring with enough free travel before binding, a low-buck higher lift setup could be had. Grinding the intake lobes to exhaust specs without welding would not require a spring change, saving welding and spring costs. A true low-buck mod, perhaps $100 US per cam.

I really like the wrx parts idea and look forward to your findings. And if that set-up works as you expect, perhaps the larger diameter sti valve can be adapted? Do you know the stem length of that valve?

Originally Posted by dynomatt

Not sure whether it's worth posting this in the other thread as well...or whether that's gotten too convoluted.

Anyhoo. Here's some random learnings.

Valve spring coil bind occurs at or about 9mm (no news there).

Using only a regrind profile (ie no welding as well), the most lift you'll get out of the cam is 9.6mm. This is a limitation of the cam journal size.

WRX valves are the same diameter (36mm/32mm) but have 104mm stems rather than our piddly 90mm.

Hydraulic buckets can have their centre bored out to make them solid. WRX buckets are solid and are also 33mm so "should fit"*

In theory* a complete WRX valve, spring, retainer and bucket should go in the same slot as the EG33...thereby rewarding us with more lift potential...for a reasonably low cost.

* - this will be tested when I get to have a play with some WRX valves in the next few days.

Matt

[NeedForSpeed]

Bill,

Looks like we have been asking Scott too many questions that he can't answer, so he bought a new 'Cam Doctor' to make better measurements. Good show!

Originally Posted by SVXRide

Harvey,
I just got off the phone with Scott and he told me he just got a new machine in that is much more accurate than his old machine. Unfortunately, it came with a 300 page manual that he hasn't dug through yet. As such, he can only do .050 right now. He promised to get on it and figure out how to get us the durations at the other lifts. He also said he'd check to confirm that the "Gold" version of the KA cams was the "hotter" version (versus the "Green" version). Stay tuned!
-Bill

[NeedForSpeed]

Harvey,,

How much does the VE drop with 9mm lift?

Originally Posted by oab_au

That is about the same increase that I saw, in the 7mm to 8mm increase. The torque peak didn't rise by much, but the torque did not drop off as fast, running into the 6000 range to increase the HP. But with that 1mm, there was a drop in the VE at about 3500. I'll run a few models, to show what I mean.

Takes me a while, stay tuned as Bill would say.

Harvey.

Harvey.

[Trevor]

Greetings Bill,

For what is worth, having been there many times and done it, I perceive a mugwump bird possibly in flight here.

Forget computer generated figures, they are simply estimates from a program built up, from widely dispersed facts and packaged for sale. Your nose at the grind stone intuition, is superior to the abstract. Make your decisions based on what you can directly estimate from what is in front of you.

Matt I think has the right idea, with modifications to the absolute maximum within your practical limits. What else is there to consider in respect of theory? You are not in the position of designing from scratch. You are simply involved in logically putting together an on hand jig saw puzzle.

In respect of valve lift, you will not go wrong in confining consideration of any modification as simply an improvement to OEM on a percentage basis. Open area is directly related to lift. Any contingency involving cam area through lobe shape, is small by comparison and is unlikely to affect any final decision over and above that which is practical. As I understand it you are stuck with utilizing available profiles. Choice is not likely to be critical and the best available will surely be obvious.

Have faith in your own decisions. Trevor.

[oab_au]

Originally Posted by dynomatt

Not sure whether it's worth posting this in the other thread as well...or whether that's gotten too convoluted.

Anyhoo. Here's some random learnings.

Valve spring coil bind occurs at or about 9mm (no news there).

Using only a regrind profile (ie no welding as well), the most lift you'll get out of the cam is 9.6mm. This is a limitation of the cam journal size.

WRX valves are the same diameter (36mm/32mm) but have 104mm stems rather than our piddly 90mm.

Hydraulic buckets can have their centre bored out to make them solid. WRX buckets are solid and are also 33mm so "should fit"*

In theory* a complete WRX valve, spring, retainer and bucket should go in the same slot as the EG33...thereby rewarding us with more lift potential...for a reasonably low cost.

* - this will be tested when I get to have a play with some WRX valves in the next few days.

Matt

Good info Matt, do you know if the difference in the WRX assembled valve length+ lifter, is the same as the Eg33 assembled valve length+hyd. lifter?
Could be the same? as the sodium exhaust valve would be useful.

Harvey.

[oab_au]

Originally Posted by NeedForSpeed

Matt,

Thanks for posting this info in this thread.

To add further, and please confirm if you can, I'm told that the hydraulic bucket can 'pump up' approximately .075" more [Harvey posted .75mm plus .50mm? in this thread, about .030"-.050"]. If true, the cam base can be reduced by that same amount adding .075" lift to the cams. .280"/.311" lift plus .075" gives .355"/.386" or 9mm/9.8mm lift without welding. [Matt, did you mean 9.6mm lift on the intake lobe?]

By not welding, most of the cost involved in modifying our cams is saved. If one is comfortable with a reduced cam base and one installs a valve spring with enough free travel before binding, a low-buck higher lift setup could be had. Grinding the intake lobes to exhaust specs without welding would not require a spring change, saving welding and spring costs. A true low-buck mod, perhaps $100 US per cam.

I really like the wrx parts idea and look forward to your findings. And if that set-up works as you expect, perhaps the larger diameter sti valve can be adapted? Do you know the stem length of that valve?

Gid'ay Mate, the extra lift that we got on the Nissan RG25, was done that way. The cam profile was reground, reducing the base circle by 0.75 mm. The Nissan lifters pumped up the extra 0.75 mm. So I would expect Eg33 would do the same.

You can only get an extra 0.75 mm lift this way, without building up the lobe. You could bring the lobe up to its maximum height, and reduce the base circle, to gain the extra 0.75 mm, to give a total of 9.75 mm, if needed.

Harvey.