Hey guys sorry to bother you with the boost gauge question again but I was looking for some links to a web site that I viewed before that had the three types of tie ins available and documented for the boost. One was the MAP line, on was the AIH, and the other was the y-pipe in the turbo tube assembly. Hope you guys can find it for me
Thanks alot

 

Which way are planning to do yours? Any clue which site you were on?

 

I can't remember. I got the link from one of the posts here. I want to do the y-pipe because I need my AIH, too cold. And I don't like the MAP t because I dont think gives as good as a reading as the y-pipe will.

 

http://www.dieselmanor.com/diy/PSD3-...D3gauge-p1.htm
they have good instructions on the guage install

 

Actually it gives a better reading. Tapping the manifold at the turbo outlet will give a higher reading because it has not been diffused through the intercooler. Tappng the MAP sensor gives the same readng the engine is actually getting. If you tap the manifold post intercooler, like the AIH plug does, it will give you the exact same reading as the MAP.

 

Very true, unless you have a blowoff/relief valve in the MAP line. Then your boost guage will read a little less than the manifold's acutal pressure. If you have a regulator on your MAP line, you can install the Tee before the regulator and you'll get a true reading. Correct me if I'm wrong. It's late and my head is still a little off from breathing exhaust fumes from race gas all night -- I went to the AMA Supercross race in St. Louis this evening, in an enclosed dome.

 

you suck.

i don't like my boost relief valve, i have it placed too close to the boost gauge Tee and it makes the boost gauge jump around alot. i could be pulling 26psi on the gauge, and the regulator will snap open and the boost will drop to 20psi very fast. that is why im going to a regulator soon, no spikes... there is only about 1'' of hose between the boost Tee and the relief valve.

 

It must be the proximity between the the regulator and the tee. All the variations of boost indication controlling devices I have tried have been at least 3-4" apart.....and there has been no variation in the indicated reading between any of them.

It's very surprising to me to learn that your relief valves operation makes any difference at all on the gauge. I wouldn't have thought the valve could bleed off enough to change the pressure in front of it. I would imagine a regulator will do exactly the same thing unless you put some space between it and the T.

 

when i do the regulator, im going to put the regulator about 6'' from the actual MAP sensor, and ill have the Tee fitting right next to the elbow off of the 5-way horn. there will be about a foot of hose between it.

 

Your current valve will work fine with that much room....assuming it's working properly now. The reason I switched to the regulator in the first place was the relief valve refused to function in cold weather.

I'm not suggesting you not switch....After trying almost every option available I believe the relief valve is the best way to go. Just suggesting that your current valve is fine, save the proximity to the boost T.

 

I got a feeling this is going to be lengthy.....

The relief valve in a MAP sensor line works because (a)the volume of air in the MAP line in very small and (b)the opening on the relief valve itself only has to open slightly to evacuate this small amount of excess pressure it sees in the MAP line. This will normally cause less of a loss of boost pressure in the intercooler lines than one would see in a boot barely seeping oil.
The problem lies in trying to measure boost pressure in the MAP line. For the relieve valve to open, the MAP pressures have to be greater than the actual relief valve setting but when the relief does open, pressure will rapidly be reduced starting in the line at the relief valve, quickly moving back to the Y-pipe tap until pressures are equalized, causing somewhat of an oscillating pressure in the MAP sensor line for a short period of time. Again, inside the Y-pipe, boost pressure loss would be barely noticeable if any. Like cookie stated, the closer the proximity of the tee to the Y-pipe tap the more accurate the reading will be and the pressure fluctuations will less noticeable. Since these boost gauges are not highly sensitive instruments, the pressure tube in the gauge absorbs some of these differences. If mounting the tee close to the Y-pipe, the slight difference in pressures in that close of a proximity to the Y-pipe tap, may or may not cause a 'bounce' at the gauge.

Now a regulator works a little differently. As pressure increases in the MAP line with a regulator, the diaphram in the regulator slowly begins to close the inlet seat. When the inlet pressure reaches the set point of the regulator, the seat is fully closed, not allowing additional pressure through to the MAP sensor. The pressures in the MAP line remain constant with the pressures found in the Y-pipe (small fluctuations due to restriction of the tap not mentioned along with a small bounce in pressure when the seat closes). Therefore, with a regulated MAP line, proximity becomes less of an issue since the pressures found in the MAP line remain fairly equalized throughout the length of the line.

If I were running a relief valve system, I would most likely want to tap the Y-pipe on the outlet side of the turbo or use the AIH delete plug to rid myself of as much of the pressure fluctuations that I could that may be found in the MAP line or at the very least, right at the tap.

 

Thanks for the information on the MAP t, i did not know that. I will tackling that asap. I was wondering just one more thing....can I buy the t at a local hardware stor or do I need to buy it through one of the online diesel sites?

 

That was one of the reasons I switched. It nearly refused to fucntion when cold, which does me no good. The other reason was the fluctuations in the intake. Watch some of the video's about the regulator vs relief valve on ITP's site. There are some links to the videos on the listing for the regulator. It may not be super scientific, but it proves the point. It helps to visuaize guzzles excellent explaination.