crownaviation

Hang on... I never said "boost" in a blanket statement. No, this was not a twin-screw, centri, or turbo application and I have never thought of trying it on any other setup so can't tell you either way how those would react. They will all behave differently.

Unlike the twin-screws you mentioned, we are running a roots pd blower. They do not "compress" anything going thru the blower itself. They are very simple air pumps. Our bypass is not there for any kind of "heat" relief as you stated. We are connected directly to the crank unlike a turbo car and would otherwise be making boost anytime the car was running. That is not so good for street manners. Our bypass is there to effectively control the boost under those conditions. Your turbo setup takes time to spool and when it does it hits like a ton of bricks. Your bov is there to keep from spiking the system with a crapload of unwanted and fuel starved boost. That has a nice way of killing motors. There are plenty stories of that going around. You guys control the big end,, we are stuck begging for more up there and do about anything to get it lol.

Not sure how the stock tune would handle the lag (by your statement, obviously not so well). You really must have nailed it to blow two holes in your block.. You would have to have some appreciable boost (maybe after the lag) and subsequent detonation to have anything close to that happen. Our setup will go into limp well before you could get anywhere near that as it is a very steady and predictable rise.

I never said "don't tune the car". That is rediculous. On this setup if you are mindfull of what you are doing (and there are no other problems) the car absolutely does fine. Not as a daily driver, only to baby it to a shop. You just HAVE to stay out of boost which is not hard hard to do with these. A $50 boost gauge and a way to monitor fuel/spark/AFR goes a long way.

Would I blindly make that trip.. heck no. All the tuners I asked said as long as the numbers looked good then it should be fine and it was. Of course, they all said they were not liable if something did go wrong.. naturally. From my observation with my car, the computer did a good job correcting with room to spare. We were actually quite surpised with the datalogs or I would not have attempted it.

Is there some risk? Absolutely. So far I guess we must have all got lucky with this particular setup... no "explosions" reported when doing this..

Simon1

The point of the bypass is to avoid boost and heat. Roots or twin screw, bypass functions for the same reason. One is pre-manifold, the other compresses within. Regardless, the function and reason for existing is the same.

When you put statements on here about driving around any boosted car with a stock tune, people are going to think it's okay. It is not.

Simon1

As with most modern turbos, lag is very slight and controlled. It was only 6.2 psi, measured In the manifold.

Stock tune, boosted car, bad.