Superman09

iTrader: (65)

It not just that, but rather too small of a wastegate in conjunction with many other factors such as the turbo size, gate used, boost pressure it was set at, and controller use to cause a random spike. However we have combated that issue as best as possible on our end with the kits by bumping up both the piping size and the flange to a 44mm on all remaining V1 kits. On all V2 kits we pull from both banks in the line of exhaust flow to a 44mm flange. We do have several dozen set-ups running without any boost spike issues on original V1 kits as well leading to it being a combination of items to cause a random spike. We feel you shouldn't have any issues with WG placement or exhaust flow to the gate to cause a boost spike, however there are more factors that can also cause a boost spike as well not related to this as well.

HolyShiznit

iTrader: (11)

Agree with Superman/Jon/HuronSpeed. My combination was unique and has a lot of exhaust flow with the stall/auto/gearing/etc that encouraged the spike. I will say that even with a 60mm wastegate AND messing with some of the WG entry points with the manual boost controller it still goes up and boost still falls by redline. Most likely caused by backpressure to a certain degree. My new boost controller with wastegate duty cycle control will help combat this.

Ultimately Huron Speed will end up selling me a bigger turbo.

PewterZCar

iTrader: (2)

I haven't had a single issue with boost spike on their v1 kit. All my vacuum is coming from the intake

HolyShiznit

iTrader: (11)

Even with vacuum sourced from the intake it still goes up to 14 for a split second and falls to 11. Without the manual boost controller it just sat at 10psi. That's with a 13psi spring in the 60mm Precision.

PewterZCar

iTrader: (2)

I run the cheap XS power 38mm wastegate and an aem tru boost. All the way down to 7 psi it is steady as can be. On an 8lb spring it makes 7.7 psi and on 10lbs spring it makes 9.5. I would think your precision would work better than that.

HolyShiznit

iTrader: (11)

Don't know what to tell you. It is what it is. Maybe its just my particular combo with the cam.

LT1RAY

iTrader: (21)

V1 kit on my car, purple line is boost in 2nd, 3rd, and 4th gear. Nice and flat.



Here's a log from when I had a 4l80 in this car last year. Spun a little at the beginning, that's why the boost line dips as I pedal it. Green line right below boost is throttle. But again, boost is flat without a spike.




I've never experienced a boost spike with over 10k miles on this setup. That's a boost controller issue. These runs were on wastegate only using a Turbonetics 7875 (82/75 exhaust wheel, .96 a/r) and a Turbonetics 45mm wastegate.

HolyShiznit

iTrader: (11)

If it was a boost controller issue (currently use a manual) then why does it only generate 10 psi on a 13 psi wastegate spring?

Also my turbo is a .81 not the .96 outlet. Its what I was shipped from Huron Speed.

LT1RAY

iTrader: (21)

10lbs on a spring that is suppose to make 13lbs isn't a bad thing. Wastegate springs aren't an exact science as every combo is different but they are very close. All of my springs have been - 1 over what the manufacture rated them at. And without the boost controller it doesn't spike per your earlier post.

.96 is the a/r size of the turbine housing, not the outlet size.

HolyShiznit

iTrader: (11)

Yes I know but according to Precision the .96 have a 3 5/8" exhaust as opposed to the .81 with a 3"

Superman09

iTrader: (65)

No, they both have a 3" outlet. 3 5/8" is just a funky way Precision measures their outlet, both have the same size discharge.