What are you guys using for an intermediate road race cam. By intermediate; I am looking for a set of cams that will take advantage of my larger turbo (gtx3071r gen2), increase mid-range to top-end performance but not so aggressive that it will no longer be a daily driver. The GSC-S2 seems to be a popular set, has anyone used JUN's mix'n-match cams or Tomei's PROCAMS?

https://www.power-division.com/4b11t-evo-x-camshafts/

https://www.junauto.co.jp/products/c...t/4b11.en.html

https://www.tomeiusa.com/_2003web-ca...efr_index.html

 

I used Kelford B's and they where fine for 540whp on track, reving to 8500 rpm. 640whp on street, reving to 9k

I now have GSC S2 and a CNC ported head.

Both cams can idle very close to stock with proper tuning. Both drive with perfect manners.

Here is my idle with GSC S2, CNC ported head, built and sleeved motor.

 

GSC S2 will work well. No need to experiment with mix/match cams.

 

Is breaking the exhaust MIVEC cam housing and or cam cap really a thing? I've seen quite a few companies selling them but I haven't seen many people posting about these parts failing.

 

I "upgraded" to a billet housing because there where a bunch of people breaking cam housings. I wish I didn't. I have a random recurring P0017 code since then. It actually recently made me fail inspection.

If you make sure your lash is set correctly and don't use crazy spring rates then the oem housing seems fine.

 

Any time the exhaust cam and valve springs are upgraded, the exhaust mivec needs to be turned off. It doesn't get enough oil to maintain target cam angles with the extra load from high pressure springs and more aggressive cams. The gear breaks from it slamming into the internal rotor. By turning the mivec off, the gear just sits on the lock and won't break.

@razorlab , you're getting that code because the billet housing just doesn't break. But it doesn't fix the underlying issue of the mivec gear not being able to maintain target cam timing.

 

Mine hits target no problem. I only get the code at startup randomly. That is mainly when the ECU checks for deviation. I'm still testing it out, but it looks like we have an ECU fix for this.

 

Pardon the hijack OP. Is locking out the exhaust mivec basically just like disabling egr, or does it have other non-emissions benefits?

 

The benefit is solely that you don't break the exhaust mivec because the stock system cant handle the increased load from a bigger cam w/springs. You actually lose a bit of spool up, ~100-200rpm.

 

Oh, ok so it hurts spool a little. I was kind of under the impression that the sole purpose of mivec exhaust was emissions. Thanks for the info. The way I phrased that was bad, what I meant was does MIVEC exhaust do anything other than emissions stuff.

 

With the OEM mivec exhaust mapping, it's basically for EGR operation. It all zeros out at WOT. That's why there are such nice gains just from tuning the mivec maps.

 

Thx that's some good context. So rather than being poorly engineered, it might simply be under engineered....or both . If mitsu really only intended it for emissions stuff that is.

 

Setting MIVEC maps to zero or to the degree of deviation during idle wouldn't fix the deviation problem?

Do you think that it was poor machining of the billet housing that's causing the code? Could it be fixed by degreeing the cam?

But regardless of the above stay with the stock mivec housing?

 

Would this be true for the GSC S1 cams too with stock springs?