Possible Boost Leak

[TheLucidFawn]

Hey everyone,

So I just installed a Mishimoto Intercooler on the car and everything seems fine the only issue (not sure if its an issue) is that my boost gauge on the accessport is reading -5 while lightly on the gas (3500 rpm) use to be around -8 cruising around. Off the throttle while cruising it drops to -10 (which I believed to be normal before just means engine is creating a vacuum like it should) boosting seems great (16psi) overboost seems great (21psi) but the turbo is a little louder than before which I have read could be the turbo working harder to compensate due to a boost leak. I don't notice a drop in power or lag. I just dont know if anyone else has seen a change in boost pressure (assuming there is no leak involved) when changing intercooler systems. The only change I have noticed is boost pressure while cruising and turbo being a little louder. So basically what im asking is do these cruising numbers seem normal? Please help and thank you if you took the time to read this!

 

[Business6]

You've got more volume to deal with so you will have more lag. I just installed the Levels intercooler which is only 30% more volume than stock and I definitely feel more lag.

I had the stage 1 dizzy tune on there after installing it and my boost won't go above 22.5 under fourth gear and it's the same with the dizzy stage 2. Prior to it I could routinely hit 23-25psi in basically anything other than first gear. I hear distinct, high-pitched air under boost from the driver's side that I assume is a tiny leak from the stock clamp that I still have on the cold side at the IC. Might be the same for you.

Only thing is that WGDC Actual shows normal range, never goes above 83%, which would not be the case if I did in fact have a boost leak. I'll just have to double-check at some point. But yeah, replace the stock clamps

 

[TheLucidFawn]

My boost is right around the same as it was before the Mishismoto Intercooler. I will need to get someone to rev my car so I can listen for boost leaks. I will check that though for sure. What about your cruising vacuum/boost lvls? Do mine seem normal?

 

[Ford ST]

I'll be honest with you no one pays attention to their vacuum numbers.

I installed a mountune intercooler this week I also hear more turbo noise, but that's probably because one it's larger and two the air flows through it better.

Sent from my LG-LS997 using Tapatalk

 

[Business6]

Yeah I don't look at vacuum numbers, either.

I've got a data log a few weeks before the intercooler install so I'll do it in the same area again and see if there's anything that stands out.

 

[Ford ST]

I have a blow off valve and it seems louder aswell.


Sent from my LG-LS997 using Tapatalk

 

[Business6]

And sorry, I wasn't trying to threadjack. Load up WGDC Actual in your AP gauges and see what the highest value ends up being after a pull. Generally you shouldn't go above 82-83%.

 

[TheLucidFawn]

No worries lol Im new to turbos cars. Ill do a actual boost leak test tomorrow.

 

[Gs1504]

Did you ever find anything? Dealing with the same thing

 

[Dialcaliper]

Just FYI, significantly increasing the intercooler size on a small turbo can result in lower boost pressures in the intake manifold especially if charge air temperatures have gone down. This doesn’t mean less power - in fact it can mean more as the charge air is becoming denser.

The reason this happens on some setups and not others is that in our situation, we are wringing the turbo’s neck pretty hard. The compressor is at the edge of the flow map putting out a lot of hot air, and can’t really much produce more flow, which is why we have a boost spike and boost tapers off to redline. (Because the turbo is too small for the engine). Our boost map isn’t dumping a lot out the wastegate, it’s more just preventing the turbo from going overspeed and destroying itself. In this situation, the cooled charge air reduces in pressure.

In a bigger turbo setup, where the wastegate is still bypassing off a lot of flow to regulate boost pressure down, cooler charge air simply means the turbo has more to give and will just flow more air by closing the wastegate slightly. In that case, you won’t see a drop in the boost pressure as long as the tune is set up that way - with pressure as the target. Some more modern ECUs with electronic boost control will be targeting derived measurements like torque or airflow and may still see the same behavior.