Rally Anti-Lag and BOV

[Slahm]

I am about to tune rally anti-lag on a stroked (2.3L) 4G63. Should have the engine installed in about a week.

I am wondering if the BOV should be bypassed, or left alone as related to the spool up. I am less worried about turbo abuse than I am spool up time, as I plan to re-bearing the turbo often, running the rally anti-lag.

Any thoughts as to the BOV, and whether it is better to keep pressure in the system, or if the turbo will maybe spool faster or keep spooled better with the BOV open, rather than bypassed...?

Thoughts, hopefully from someone who has played around with rally anti-lag?

Thanks!

 

[hypergenesis]

Well if you think about it if you keep your BOV recirculated some of the excess pressure goes back into the system. On most cars without SD not having it bypassed the car dies between shifts since the pressure isn't put back into the system. BUT i might be wrong im just using my knowledge of a regular 4g63 and what happens with the BOV when its bypassed or open.

A.

 

[H@xtGSX]

I have seen several rally built cars that run without a BOV. It does help with spool between shifts, for sure, but there is a long debate about whether the resulting off throttle surge actually damages the compressor or not. Personally, for a race car, I'd get a billet compressor wheel and run without one.

 

[Slahm]

I have seen several rally built cars that run without a BOV. It does help with spool between shifts, for sure, but there is a long debate about whether the resulting off throttle surge actually damages the compressor or not. Personally, for a race car, I'd get a billet compressor wheel and run without one.

I can handle wearing the bearings faster, as the Rally Anti-Lag is going to burn them up anyways, apparently. Are you talking about wheel failure? Great! I had not even thought of that yet!

I have read and read here on the forums, and there are TONS of articles talking about turbos, but with many conflicting opinions. For quick spool, without(or with) a BOV, is there an article that more clearly talks about spoolup time? Or maybe someone can tell me about their experience with spool times, preferrably with a bolt-on turbo, rather than a customs twin scroll setup(I don't have time yet to create that, looks tough!)

Thanks again

 

[H@xtGSX]

Yes, I was referring to the compressor wheel breaking off fins from surge. Cast wheels may be more prone to this, which is why I say I'd use a billet wheel... Like the Batmowheel. That is an awesome compressor. Look it up on Google. If I could afford it, I'd already have one.

There's not going to be one easy source for the information you want because a lot of that depends on the quirks that are unique to your engine. The problem, as you have seen, is that there's more than a few ways and philosophies about how to set up your turbo. Spool time is exhaust manifold pressure dependant, so naturally the more air you retain between shifts and force through the motor, the better your spool should be. Other options include ball bearing CHRA's, water/methanol injection, decreasing the intake piping volume by running a water/air IC or a short route FMIC, and using an anti-lag device or program.

 

[Slahm]

Well, I am going to use Rally Anti Lag, via ECMLink 3, I think I will try the BOV both ways, and see what happens... I also planned to play with Water/Meth injection, but I will likely have to wait a bit, too many mods, too little time!

I will post the results in a couple weeks, as the engine is still being built.

Thanks!

 

[NHerron]

Have you looked into using NLTS? With NLTS, you dont release the throttle upshifting. I don't use anti lag but using NLTS keeps my E316G spooled no less than 4psi lowered from target boost between up shifts. If using AL+NLTS, I'm sure it would hold target boost.

I'm not into rallying, so not 100% here but no compressor relief and no NLTS + ANTILAG seems like it spells disastor. If the throttle closes, turbo cant relieve itself plus something is still forcing torque on that turbo, something may break, coupler blows off, or at the very least severe detonation upon hitting the gas again due to the overheated air charge.

So if rallying uses no BOV, I think theres more to it and more tuning to be properly setup

 

[Spoolin92GSX]

I've read up a good bit on different styles of anti lag recently, so I'll throw my. 02 in here. Like NHerron said, no BOV just sounds like trouble; even if you have NLTS you still have to lift for turns/braking. Aside from timing-retard ALS rally teams also used to "recirculate" the BOV into the exhaust manifold, so you have the benefit of relieving intake pressure and assisting turbo spool.

I'm not sure how those methods would work together though, since the timing-retard will be spooling the turbo and creating back pressure in the manifold. You might have to check back pressure in the manifold before you go that route to be safe. And keep a BOV on there to be safe as well. Good luck on making the decision

 

[hazmat6135]

the best rally cars in the world have their BOV. it is essential for the longevity of the turbo and intake track. when you close the throttle the excess pressure needs to be relieved. if it isn't that puts stress on the turbo and the throttle plate plus all the seals/ couplers along the way. for best spoolup between shifts you should have your BOV recirculated. when you shift that allows the air out of the intake track but back in front of the turbo helping keep up the spool. that is the intention of it in the first place. you can still run SD or a GM MAF after the bov and have it recirculated without any issues. hope this helps good luck with build.