ShutupAndHoldon

I have seen several posts saying the 710n TT valve offers better throtle response and lower lag after shifts than the stock valve. It seems to me that the best performance and response would occur with the lightest spring that can hold the max. boost. This would allow lower vacuum levels to pull the valve open and reduce spool down. Is this right, wrong? (why)

Kent L

Especially if you are chipped and pushing upwards of 1.2 bar of boost.

ShutupAndHoldon

Taking this to an extreme a 5lb spring would open under 5 lbs boost. The result would be a car with limited power. If it was a 200lb spring the boost would be max generated by the engine but it wouldn't open to bypass on shifts, so the result would be lag as the turbo respools after a shift. If this is right, it is opposite to what people are saying (Bigger spring = less lag). Where am I screwed up on my understand?

ChaoticS4

That's why it's hard to guage unless you have an adjustability factor for the spring. Forge's and Bailey's don't have adjustability tho.

but mine do... hehehe

Kent L

I don't think people blatantly say higher spring rate = less lag. There is a happy medium between the two. I think the first priority for changing out BPVs is to eliminate any boost leaks when running higher boost or even stock.

Since the stiffer spring most likely has a quicker recovery time, the engine can also build boost quicker after shifts. In addtion, since the spring travels a shorter distance, less boost is "lost" during the shift, increasing performance.

Tostao

LARGER spring? You meant STIFFER right?