Carnesd

If you drive the car with an open downpipe people say you boost 1-2 psi higher than with the exhaust hooked up. How can this happen if your wastegate is set at a lower psi? Shouldn't it open when you hit your desired boost level? Thanks for the info. My turbo project should be done in a month or two.

Carnesd

Nobody knows? hmmm.....

steelcityhonda

less restriction, turbo spools quicker, which means you get more boost.

projekteg

MikeJ-2009

You probably couldn't. That doesn't mean that anyone explained it. What does spooling the turbo faster have to do with the amount of boost it will put out. Does that mean that turbo's that don't spool as fast can't achieve the same amount of boost? I was interested in a more technical answer, but that ---- doesn't make sense.

projekteg

there is no restriction, therefore the turbo basically isn't waiting for the exhaust gases to leave before it can push more out of the exhaust which in turn would couse it to spool a little slower and not spin to it's full potential while under boost. i don't know if this is any better than before

Carnesd

I understand what your saying but less restriction shouldn't have any affect on the wastegate and what boost level it opens at right?

Semnos

I have a lot of experience with this...as now that is my main problem...again.
My turbo has a really small turbin. so with open downpipe and now just with a straight pipe...it spool quick but not only that the wastegate opens at 7-8 psi, but when I reach 6K it begins to boost up to 15 psi. Because of the small turbine and no or little restriction the thing just keeps on spooling and making more boost even with the wastegate open. I had it on my crx to...but when I put the stock 1.5 inch exhaust to the downpipe....boost was kept at 7 psi.
So now I'm going to make somekine of silencer/restrictor at the and of my midpipe to restrict the flow a bit to create a little bit of backpressure at the higher rpm's so that the turbo doesn't boostcreep like a ****.

Carnesd

I think you just hit it dead on the head. Because the turbine is so small, even with the wastegate fully open, there is still enough pressure going into the turbo to keep spinning it. I guess the only way to stop this would to make a bigger wastegate hole and position it so that all of the exhaust will go through that hole when the wastegate is open. THanks I learned something new today.