jspecracer7

Boost creep is when the exhaust gas coming from the engine overloads the wastegate and instead of it exiting thru the wastegate when desired boost is reached, it exits the turbo...causing it to spool more which in turn causes it to boost more and makes your turbo boost more than what you want it to.

jspecracer7

No. Wastegate size is VERY important. You don't want to boost 1.0 kilos on a T-04E with a stock fuel system...that's close to the border of fuel starvation. I've seen this happen because the wastegate was too small. If the owner had just bought a larger wastegate, instead of an "adequate" one he wouldn't have been in this predicament.



Size the wastegate so that you can run the LOWEST amount of boost possible. Then use your boost controller to turn boost up. [/quote]

Yeah, that's exactly what I was saying. Sizing a wastegate isn't an exact science. It just has to be big. [/quote]

lol...in the easiest terms you and I can think of...Bigger is better

little rotor

I remember reading something once that said that if an external wastegate is too big the valve sits very close to the seat and can damage it. I can't recall the logic behind the claim. Basically the artical said to only go as big as you need to eliminate boost creep. I don't know if this is true or not, but thought I'd mention it to see what other people thought.

I've also noticed some people getting away with running reasonably small wastgates in cases where the manifold design has been well thought out in regards to flow to the wastegate.

GarageBoy

How does the boost controller make you turbo boost higher?

TYSON

Damage may be caused because the bigger wastegate has to cycle open and closed more often so that it doesn't release too much exhaust energy. The damage could happen becaue the poppet is bouncing off the seat so often.



Buying too large a wastegate will also damage your wallet, unless it is too thick to begin with.

TYSON

Boost controller uses air pressure to hold the wastegate closed beyond what its internal spring would normally allow. This forces more exhaust gasses to exit through the turbo, spinning it faster and voila, boost rises!

GarageBoy

Thanks! So the boost controller uses soleniods to alter the airflow?

TheCamel

Most electronic units have a boost control solenoid, but manual boost controllers use a vent that bleeds off the boost pressure that would force the gate open, Think of it as a water faucet, the more you open the spigot, the more water is sent through the faucet, in a manual boost contoller the boost pressure comes from the turbo, is sent through the valve and only so much of the boost pressure is sent to the wastegate. As boost rises more pressure is going through the valve, what the valve does is vent that pressure slightly to keep the wastegate closed in the turbo longer, until enough boost pressure makes it through the valve and opens the wastegate anyway. This is a simple setup and had been toyed with using common household items such as fishtank air bleed valves. The problem is that when you get into large turbos or high boost levels the 15 cent fishtank valve is going to explode, or melt from the heat, in this case all of the boost pressure that would open the wastegate vents traight to atmosphere. This is a BAD thing, the wastegate will not open, you will see boost levels you never dreamed your turbo could produce (like 30 psi) If you can catch it in time you might be safe, but highly doubtful, in which case an extreme lean condition will hit the motor and you either pop apex seals, melt spark plugs or in a piston engine you may find that the pistons melt or find new homes outside of the block



Also when installing a boost controller, use quality lines, The Pep Boys special silicone hose kit for $39.95 is not going to withstand the boost pressures like a good fiber reinforced rubber line.



On a side note, if you decide to go with a large external wastegate and vent it to atmosphere w/ a larger turbo (TO4S or larger) I highly suggest a good set of ear plugs.

1Revvin7

So how do you determine the right size wg for your application?

TheCamel

I have not really seen a mathmatical equation that says for X amount of boost on Brand Y turbo use Supergate G. It depends on boost levels, motor porting and other factors. Using a 60mm wastegate on a T-88 Goliath with stock ports and a 76.3 exhaust is not going to do much, boosting .6kilo. You have to look at the flow of the turbo and what type of exhaust you will be running. Most kits on the market now have the correct wastegate for the manifold/turbo combination. Another thing to look at if buying used manifolds is to measure the output flange for the wastegate on the manifold itself. In my case I have a weird flange, and need a 50mm or larger wastegate to handle the T45s I have. I talked with the guys at Dragons shop (IGY, Dragon, JSpecRacer7, and Scott and Beau) and nobody had a definitive answer as to what would be the best unit for my application (HKS's new wastegate was brought up a few times) but most of the responses were "BIG" I don't think any of them have one smaller than a 50mm