Boost Gauge for my 6v92ta

MCI5A · September 29, 2016, 05:22:49 PM

Hi all,

I've been working on my MC5A after a trip to Challis, Idaho a few weeks back. Interesting trip .. lost my jakes on day one, the stereo quite in Vale, Oregon that night and broke a cooling fan belt (miterbox)the next day just before Twin falls, Idaho and finally my tach quite on Hwy 140 (southern Oregon) just before getting home.... All this aside, we had a great time at the Braun Brothers reunion in Challis, it was really fun.
So having fixed most of the problems from the trip, I thought I'd install a turbo boost and pyro gauges to help keep an eye on things while on the road. The pyrometer was no problem since it had been wired by a previous owner and just needed some TLC. But I can't locate a bungle to install a pickup for the manual boost gauge. My turbo is a Garrett TV7513 A/R .75. I don't see any plugs on the turbo or the top of blower.
Any help appreciated.
Tom

luvrbus · September 29, 2016, 05:31:57 PM

You have photos you probably have have a side mounted turbo with a non Detroit air horn the factory air horns have 3 taps

MCI5A · September 29, 2016, 05:48:24 PM

So this is going to sound dumb, but the turbo air horn you're referring to is located between the turbo and the blower or between the air filter output and turbo input ?
My turbo is mounted low on the drivers side at approx. the height of the valve cover. I'll try to get some pictures tomorrow.
Tom

lostagain · September 29, 2016, 05:49:20 PM

I drilled and tapped a hole in the intake between the turbo and the blower. Ran a hydraulic hose from it to the fire wall (to withstand the engine compartment heat), then a 1/4" air line to the dash. To a 0 to 60 psi pressure gauge. Works good.

JC

MCI5A · September 29, 2016, 06:03:58 PM

So, JC did you remove the tube from the turbo out to blower in, before drilling and tapping. So is closer to the blower side more accurate than closer to the turbo ?
Tom

luvrbus · September 29, 2016, 06:18:08 PM

Sometimes I just use a metal Schroeder valve (tire valve stem) and install it in the rubber connector,for the most accurate reading it needs to be as close to blower as possible that's were Detroit had the tap

Iceni John · September 29, 2016, 08:17:58 PM

I use a VDO 30 PSI turbo boost gauge - the most boost I get is 26 PSI. I originally used some 1/4" DOT nylon air line running from the 1/4" FPT port on the driver's side of the air horn (where my old Quick Start ether injector had been previously installed) all the way to the gauge, but one day I heard a loud PSSSSTTT as I was driving and noticed that my gauge was showing zero boost. The air after the turbo is so hot that it had melted the air line; I now have a few feet of 1/4" copper refrigeration tube from the air horn to dissipate the heat before it joins the plastic air line.

Where I find the boost gauge most useful is when climbing long grades in hot weather - if I keep about 18 PSI boost at 1900 RPM on a 3/4 throttle in 3rd gear, then it won't overheat.

John

blue_goose · September 30, 2016, 06:51:11 AM

one eight in. DOT tubing works good.
Jack

lostagain · September 30, 2016, 07:04:34 AM

Yea you should remove the intake tube before drilling, so you don't put metal filings into the blower.

JC

Geoff · September 30, 2016, 05:20:44 PM

The pyrometer is all you need for driving. A mechanical turbo boost gauge loses a lot of pressure after 40 or so feet.

--Geoff

Oonrahnjay · October 01, 2016, 07:19:25 AM

Quote from: Geoff on September 30, 2016, 05:20:44 PMThe pyrometer is all you need for driving. A mechanical turbo boost gauge loses a lot of pressure after 40 or so feet.

--Geoff

Especially during transient conditions where the pressure is going up and down quickly.

Iceni John · October 01, 2016, 06:54:30 PM

A mechanical boost gauge is reading only static pressure, not flow. 26 PSI at one end will be 26 PSI at the other end, regardless of how long the tube is. If not, where is the static pressure going? It cannot just disappear into thin air (so to speak). The only thing affected by the tube's length is the speed of response, not the pressure itself. My gauge reads different boost pressures almost as quickly as the turbo changes speed, in other words there's almost no discernible delay, and that's with about 45 feet of 1/4" DOT air line.

John

lostagain · October 04, 2016, 08:04:22 AM

Mine reacts instantaneously, as it should.

JC

blue_goose · October 04, 2016, 08:38:01 AM

You only need 1/8 in. DOT tube from engine to dash.
Jack