[Dynomite]

I have a client that has brought us a Snow Performance kit to install. Last year they switched to an external electronic boost sensor instead of a vacuum line into the controller.

Just wondering if anyone has installed one of the new kits. I'm wondering where to tap for a boost pressure reading. Thanks

 

[J.Knight]

You just need boost pressure? The port on the LIM just above the coolant elbow is probably the best source of boost for a sensor.

 

[Dynomite]

You just need boost pressure? The port on the LIM just above the coolant elbow is probably the best source of boost for a sensor.

Yes the new meth kits don't use a vac line they have an electronic boost sensor that needs to be tapped in. I'll have a look at the spot you mentioned. I appreciate the response

 

[Dynomite]

We tried a T off one of the vac lines into a brass fitting adapter. Nothing registering just revving in park but haven't tried a road test yet. Fingers crossed

 

[J.Knight]

The location I mentioned should be providing boost pressure to the fuel pressure regulator and MAP sensor as well. Your other option would be to drill another hole in the LIM near it, pipe tap it and thread a brass fitting into it. Obviously just be cautious of debris entering the intake manifold.
I see you’re Canadian as well? Where you from? I’m Ontario near Hamilton.

 

[Dynomite]

We're near Trenton Ontario. From what you've described I would say we're in the right location. Like I said we tried revving it up in park to see if there's anything showing on the gauge but we're not getting anything. We'll try a road test. I need to find a manual gauge to test it.

 

[Dynomite]

I also noticed the gauge range is 0-100psi. Perhaps not sensitive enough???

 

[dezldave961]

J.Knight is correct that the vac line sourced from the LIM is the proper one to tee off from, which is also running to the MAP, fuel press. regulator, and boost bypass valve (pick the best spot you can add a clean tee fitting).

This is no different than the previous kit's need for a source... you're just running a hose to the sensor/controller vs. turning it into a signal right at the engine with a sensor.

You won't see much boost in park, as there's not much load on the engine, so it'll be bypassed a lot on purpose. And yes, a 0-100 gauge is not going to give you the best resolution for seeing a car that makes ~6-8psi stock, and 12-15psi in majority of modified setups (so barely over 10% of that gauge's range is useful).

 

[J.Knight]

If you have a hand held Mighty-Vac pump the gauge usually has a vac and pressure side with a needle in the middle. It’ll read pressure up to around 30psi I believe.
If you have it T’d into that fitting on the LIM you’ve got the right spot.
It keeps getting called vacuum lines or fittings but it’s actually boost reference pressure not vacuum.

 

[J.Knight]

We're near Trenton Ontario. From what you've described I would say we're in the right location. Like I said we tried revving it up in park to see if there's anything showing on the gauge but we're not getting anything. We'll try a road test. I need to find a manual gauge to test it.

Trenton is about 3.5hours from me. But I fly there occasionally.

 

[dezldave961]

If you have it T’d into that fitting on the LIM you’ve got the right spot.
It keeps getting called vacuum lines or fittings but it’s actually boost reference pressure not vacuum.

It sees both, just that vacuum is majority of what's in the manifold, aside from when you're into the pedal enough to make boost. Also good to keep that nomenclature when buying lines/hoses, otherwise you may buy/install something that'll suck shut under vacuum, despite being rated for positive pressure/boost (ex. soft rubber tubing or hoses).

 

[J.Knight]

It sees both, just that vacuum is majority of what's in the manifold, aside from when you're into the pedal enough to make boost. Also good to keep that nomenclature when buying lines/hoses, otherwise you may buy/install something that'll suck shut under vacuum, despite being rated for positive pressure/boost (ex. soft rubber tubing or hoses).

Fair enough.

 

[Dynomite]

I believe we're in the right place but all we're getting is vacuum. We've tested the gauge by blowing compressed air through it and it is reading. However we're not getting any boost reading doing a road test.

If you have a hand held Mighty-Vac pump the gauge usually has a vac and pressure side with a needle in the middle. It’ll read pressure up to around 30psi I believe.
If you have it T’d into that fitting on the LIM you’ve got the right spot.
It keeps getting called vacuum lines or fittings but it’s actually boost reference pressure not vacuum.

 

[dezldave961]

#1 - photos always help tell your story better

#2 - if the engine is still acting the same, making boost, etc... The part you're adding on is the culprit (did you test the gauge at just 10psi like the car would output, or wall pressure of 90-100psi that has the strength to move a stubborn needle?)

Details matter, which is what you need to look into, especially when another person comes to you for help.

 

[Dynomite]

We have it T'd into what I believe is the boost reference? Anyway, we blew 70psi through the sensor and it did display on the gauge. We took it for another road test and really got on it and finally displayed a reading. However we're only getting 1-3psi at WOT. Maybe some belt slip?

 

[dezldave961]

At the pulley you're probably dealing with, belt slip isn't likely an issue, unless you have an absurd amount of slack/stretch on the belt. I've worked on builds down to 2.55" without slip concerns, as long as the belt/pulleys are setup right/tight, without requiring any add-on bracket (8-rib conversions help at that point).

(Edit: a simple trick is swapping the smooth s/c 3.0" tensioner and 3.5" idler pulleys for a little more wrap on the s/c pulley... After that, going to a 3.5" on both can take up some belt slack, if you have one sitting around. If you're having to fully crank down the tensioner to install the belt without it springing back much after, your belt won't be the issue on anything down to a 3.0" s/c pulley or even smaller. You can also run the Bonneville/Park Ave tensioner/coil bracket for more wrap, but will also need a newer L36 dogbone mount, which needs a hole drilled/tapped behind #3 injector that most L67's don't come with. I've gotten to a 2.7" 6-rib on my GenV with that.)

The sensor/gauge you're using doesn't sound like it's sensitive to low values, as mentioned in my first reply. 100 psi gauges aren't meant for this application, which makes me question some other things.

Also, are you scanning the car to see the MAP readings, not to mention monitor the overall health of the car trying to be beat on? 1-3psi is barely over 100 kPa by 10-15, while even a stock pulley should register 140-160 ballpark.

 

[Dynomite]

On our last drive we did notice a coolant leak. Looks like one of the lines has a split and opens up when it gets hot. There was some coolant on the belt which made me think that it could have slipped. The owner is getting this issue addressed.

I asked Snow Performance about the wide range of the sensor and they assure me that it should have no trouble reading small increments.

We do have hptuners so I should absolutely be scanning. I will do that when the car returns. Thanks.

 

[Aussie l67]

I have a client that has brought us a Snow Performance kit to install. Last year they switched to an external electronic boost sensor instead of a vacuum line into the controller.

Just wondering if anyone has installed one of the new kits. I'm wondering where to tap for a boost pressure reading. Thanks

On the boost tree .

 

[Aussie l67]

On the boost tree

 

[dezldave961]

On the boost tree

The US M90's only have that in the 96-97 models behind the bypass valve, and it was transitioned to a single access port under the s/c shaft on the lower intake.