Installed a boost gauge but.......
 

I too bought a cheapo turbo boost gauge from JC Whitney and recently installed it. I took my car out on the road and tried to keep an eye on the gauge (trying not to compromise my safety of course). Under pretty hard local street acceleration (the car didn't really get above 40 MPH though), I only noted about 8 or 9 psi. Is this really abnormal? I always thought my car felt decently peppy, for a diesel, but with everyone else dialing in 13.5 psi with their boost controllers, maybe my car isn't performing the way it could. I spliced into the tube that goes from the rear of the intake to the overboost switch near the brake booster. I think this is where Speedy cut into his lines too. Please let me know if I'm just being paranoid. Thanks.

Alex

Alex,

I don't think the indicated boost you are getting is abnormal. I remember after installing my boost gauge, I measured around 7.5 psi at 4000 rpm in 3rd gear. At what RPM did you get 8-9psi? Just remember, you have to add more fuel or the added boost will do nothing.

SW

Alex,

I'm using a vac/pres tester from Autozone while waiting on the cheapo from JC. I noticed if I floor it I get 8-9 psi @ 3000rpm(3rd-4th shift point 40+mph) I think this is the factory limit. I haven't got my home made BC installed yet.

cruising at 70mph I get ~5 psi

Anyway, I think that's normal...


BJ

Ok, well it sounds like my cheapo boost gauge is working just fine. I get 8.5 psi under hard acceleration at around 3000 RPM (I'll have to verify that later, I wasn't specifically watching out for the RPM before). The boost starts to kick in at around 1800 RPM. Under light driving under 40 MPH, it lingers at only around 2-4 psi. I will post any other observations or anything interesting I see.

Alex

Oh, I forgot to ask: is there anywhere I could attach the boost guage feed tube where I could register vacuum and boost? The gauge is made for both and I know it's possible because my Volvo turbo has a factory gauge that shows a vacuum zone, and a boost pressure zone. Thanks

Alex

Yes you are correct and have spliced into the right line. Before I did the boost adjustment, I was running 8-9 psi max boost, at about 3000 rpm under full acceleration. Something you will want to do is to check boost on BOTH sides of the overboost sensor. What you and I have right now is a reading of intake manifold pressure. The ALDA may not be "seeing" this exact amount of pressure due to a clogged overboost sensor. Either way, it's a good idea to give the overboost sensor and a good cleaning.

How would one go about cleaning out that little switch? My lines never really had any soot in them so I always figured the switch was clean, but maybe I should check it out anyway. Also, how do I tap into the line without cutting it? I had to cut the line I installed the gauge to, to install a vacuum T.

Alex

You'll have to cut the lines. Just use some rubber hose to connect the hard plastic hose back together. You can use some pipe cleaners to go about cleaning the overboost sensor.

Don't worry! Home Depot got the solution. Before you cut or clean the line, go over there buy you a roll of white 1/4" line(20'? for $2.99?). they also have the brass T connector with tightening nuts. I broke mine while cleaning it the other day. Luckily, I had it in the trunk on standby.

I finally had a chance to run my car around on the highways tonight with the boost gauge. My boost peaks at about 8.5 psi at 3000 RPM and up. On the highway, with a light foot, the boost is at about 6 psi and very quickly jumps up to 8.5 with a little more weight from the foot. Not too bad. I think I'm going to install that boost controller though because I can't even begin to imagine how much better my car would run with 5 psi more.

Alex

I recently installed a quality VDO boost guage in my 83 300D and the most I've ever seen is between 8.5 and 9 PSI of boost. Looks like your guage is right.

John

I, too, am on the bandwagon!!! I just finished installing my gauge this evening. Between 8 and 9 psi is what I'm pulling under accelleration. I bought one of the mounting brackets at Advance auto and finished the job nice. Next step....boost controller!!!!!!!!!!!!!!

Paul