Ok so trying to decide upon a head option for my 2.5 swap. I have come down to 3 possibilities: -WRX heads cleaned up with new cams-$1000 -USDM Sti heads cleaned up stock Sti cams $1000 -V7 JDM heads with JDM Ecu $xxxx Still have not got a clear grasp of what is needed to get AVCS up and running. My best research so far says that JDM Ecu and running wiring for AVCS with reflash will work. Sourcing these heads and ECU could be rough on the wallet. Is there a way that anyone knows of getting AVCS to run in a WRX minus going with Hydra? Seems that by now they would have come out with some sort of AVCS controller of some sort that could be used on the WRX. I mean really, this is not a serious problem...it mainly references TPS and such right? Frustration is starting to set in. I am really interested to see Liquidforce's dyno and maybe that will quiet me down a bit. I am getting close at this point to just saying :fawk: it and part out, sell the car and trying to grab a slightly older Sti or Mustang Cobra. But that comes with a serious car payment as well as insurance ramifications. So if someone could give me some thoughts on the options for heads, etc I would greatly appreciate it. There is just sooooo much conflicting data out there and I am trying to weed through it all to get to some solid info. I know Scott and Doug probably have quite a bit of experience in this and hopefully one or both of them could chime in.
I thought IAperformance.com made an AVCS harness and that it was all plug and play if you've got the AVCS heads. The JDM heads > USDM sti heads > WRX heads in terms of flow as well as cost.
Doing a search now on IAperformance.com thanks for the advice. Did not find anything on their site, will look elsewhere I guess. Aight did some reading on that, found a couple threads. It seems they can get you the harness, then you still require the JDM Ecu to go with it and then you also have to find something that will tune the ECU. That means killing my street tuner /AP and going with Ecutec reflash or hydra to actually control it. I have written Christian at Cobb about the possibilities and I am waiting to hear back from him. He seems to know most things tuning related, so I guess we will see what he has to say. But getting a JDM ECU is pricey as well.
Seems this might be an easy option if someone just made an aftermarket AVCS controller. Why someone has not done this yet boggles me. I mean there have been aftermarket V-tec controllers for a while now. It could be as simple as RPM based and TPS based. Combine the two and have some sort of a chart that varies the output to the AVCS solenoid.
Well after talking to Liquid he seems to think his setup makes good power and torque just fine. Going for a ride tomorrow so hopefully that will put to rest some of my anxiety about this whole process as he is running WRX heads and cams.
^^^ What he said. AVCS is nice, but I think it's far from a deal-breaker. I could always test an STi with AVCS on, and then set it all to zero to see the difference. AVCS is the opposite of VTEC, it advances the cam down low to help cylinder filling at low rpm, and then dials out in the higher rpm. It does NOT retard the cams at high rpm... SS
Scott I would love to see the difference you get between the two! That would be AWESOME for all us 2.5 swappers so that we can see a real world difference! Right my understanding is that it only advances the cam...20-30 USDM vs JDM right?... and then lets it go back to the stock 0 degree as it goes up in the RPM's. So I guess no good way of using AVCS other than extensive changes or hydra huh?
I may be wrong but I belive it advances in 10ths of a degree, therefore 40 on the avcs would be 4 degrees.
Right I think it is a total of like 5 or so total degrees or something like that. Edit: saw where I messed up my post...odviously not 20-30 degrees, lol.
AVCS is mostly just for low end grunt. Unless you want a low rpm tq monster AVCS is useless. When you are racing you are in the upper rpms after the shifts so AVCS isn't playing any role. It only comes in at the intial pressing of the gas from what I understand. I hope I'm not wrong.
Yeah I was thinking about that. Still undecided as to which heads. Anyone know if wrx and Sti have same valves in the USDM or if the Sti has larger. I think they are larger, but unconfirmed as of yet. I am really leaning towards just porting my heads and calling it a day, trying to find some different numbers. I have yet to see Sti heads on a dyno without AVCS. Supposedly Gruppe-s has done that with good results...then again Christian at Cobb swears that running AVCS cams without the AVCS is bad stuff. I am about to just be done with it, throw the block in there and see what happens. I guess I can always yank it back out if I am unhappy with it, or sell and upgrade. 1st priority right now is going to be finding a nice used 6 speed. I think it was 05 or 06 or both that could use the WRX rear end gears without change.
The 06 and 07 you stick with the same rear end. 04 and 05 6 speed you have to swap out the R&P. The WRX and the STi heads in themselves are virtually the same....its the internals that are different. STi valves are sodium coated or something like that.
Sodium filled maybe? I remember something about that as well, also the valves themselves being lighter...not sure. Hopefully SS will come through with the before and after dyno of an Sti with AVCS and without.
Every dyno i've seen shows that avcs just gives you a wider power band. Once it kicks in you've got more torque and hp just about everywhere, not just on the low end. Someone's selling jdm sti v8 big port heads. Some of the best heads available from what I hear.