Starting in this thread, a discussion about camshafts has been started. I didn't want to thread hijack, so I started a new thread and linked it.

Tom was earlier inquiring about the EG33 camshafts for his turbo application. This thread is mostly for chatting about performance bumpsticks, and also their effect on forced induction (mainly turbocharging).

I came back for a quick visit to see if anyone aside from SVXtasy has boosted, and well, this is what I get.



Above is an image of the stock camshaft configuration. I whipped it up real quick for the purposes of this thread... But in case you can't see it:

Intake: Opens 2* B-TDC, closes 54* A-BDC, centered @ 116* A-TDC, 236* duration.
Exhaust: Opens 55* B-BDC, closes 9* A-TDC, centered @ 67* A-BDC, 244* duration.

SVXride inquired about me having any camshaft experience with the EG33, and I can say yes and no. Before my X was in an accident, and thereby before I sold it, I very heavily researched changing the performance of the camshafts. I was in talks with Harvey here on SVXnet, Paeco Machining, and Chris over at EngineLogics (former F1 technician, I believe). I was a few weeks away from tearing down my valvetrain and sending the camshafts to Paeco, and then I decided to sell the car because of the accident.

Anyhow, back on topic... The general idea is that for boost applications, it is best to run a staggered lift/duration setup, skewed towards the exhaust side. Due to the turbo seeing more exhaust pressure for a slightly longer period of time, and the intake side of the engine seeing slightly higher intake pressures, the turbo can spool more quickly and reduce lag.

In terms of the stock setup, it is already setup fairly well for this. The only problem is that the cams are not very aggressive at all.

For an aggressive turbo application, personally I would suggest the following:
Intake: Opens 8* B-TDC, closes 60* A-BDC, centered @ 116* A-TDC, 248* duration.
Exhaust: Opens 62* B-BDC, closes 18* A-TDC, centered @ 68* A-BDC, 260* duration.

Giving the exhaust side more room to breathe, and for a longer period of time A-TDC, will substantially increase the efficiency of the turbo. The intake side is also given more breathability; however, it has kept the same center in order to allow a slight pressure increase on the intake side (decreasing the "workload" of the turbo).

According to Chris from EngineLogics, he has managed to give turbocharged engines HP gains ranging anywhere from 5% - 10%, simply by changing the cams to this config.

Of course you will lose the benefits of the IRIS system with this setup, as the overlap is too large for it to scavenge-collect pressure. However, with a turbo this system is hardly necessary anyway. The pressure buildup comes from the turbo! I hardly know the IRIS system as well as I know cams, but I suspect that removing the IRIS butterfly (or welding it into an open position) would be best with forced induction.

- Garrett