Thread: BOV orientation
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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
No lurching but interesting thought. Just a more responsive fealing or fealing of less lag.

Thinking out loud along those lines, if we are making 20hp off idle, .2 bar is about 5% more or one more HP. Even a stock turbo is makeing some boost outside the TP at idle. This just reduces the drop in pressure as the intake maifold is pressurized and the turbo has to respond to the new demand. If we are up to 50hp by 1500, .3 bar is about 15% more hp or about 57hp. It just comes in faster with less lag.

If at cruse if you are making say 30hp and drop the throtle there is a sec of lag as the turbo has to respond to equalize pressure. This reduces that lag time. Anyway .6 bar might jump you to 45hp a sec faster and quickly build from there. At least that is my guess.

It is not like trigering NOS and getting a quick 50 or 100hp, just less lag time and more NA like response.

I may not have stated my point well or accuratly as to shifts and agree with what you are saying. However I recall I did not have to wate for boost to build back between shifts and it seemed like my boost guage stayed pegged.

The improvement was not as dramatic as when the factory BOV had failed and it is fixed. However before the improvement it seems like it took some one or even two sec to fully rebuild boost between shifts. With the change it seemed a significant improvement to where I stayed on full boost between shifts instead of wating for boost to come back. There was no longer any detectable lag between quick shifts.

I was mosty trying to make my point well enough for others to want to try it and for them to try to develop a base of referance to work from. It more or less gives one a little head start and reduces inital lag. After a sec or two of WOT there is probably no differance and it dose not add any peak HP.

CIS is know for its lag and many spend a lot on exhausts, turbos, light weight flywheels and other goodies to try to minimize it. This is just one of many things that can be done. When I got done developing my 91 Turbo with this and a couple of other goodies the differance was night and day in lag reduction and I already had B&B's, ports, cams, larger IC... to start with.

I do not know if this is any validation but the "Synapse BOV" is well received and I think took a top product award at SEMA one year. It dose the same thing. If I do not have the credibility, see what they and others have discovered.

There is another step up from this to an anti-lag stragy where the turbo blead between shifts can be sent to the exhaust primary tubes to further energize and spin up the turbo in reserve. Some of the early non Porsche street turbos were even delivered with the plumbing in place so it could be use in racing. Could hook it up to the exhaust air injection manfold.

Fun stuff. Another fun thought is most guys send a lot of time wanting to improve turbo lag. However, they pull there air pump to save a couple of pounds and 5 hp. However, doing so effects turbo lag. Same with removeing the de-accel valve. Doing so has some impact on turbo recovery time and removes the only safety margn if the anti surge valve fails. Probably another "Belive it or not" moment I guess.

I love CIS.

Last edited by 911st; 12-08-2009 at 01:46 PM..
Old 12-08-2009, 01:44 PM
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