hi guys just installed a boost gage off turbo on exhaust about 16 " from turbo where a plug was in pipe. went for a drive and could not get more then 5lbs of boost at full power going up a hill, is this ok ? no smoke, runs up to 83 mph thanks dave
You're not meaning that you put the gage on the exhaust side of the turbo, are you?
The boost gauge should be installed between the turbo and the intake manifold, not on the exhaust side.
That said, If you're looking at the exhaust side and see 5 PSI, I'd wonder (besides the gauge being in the wrong place) why there's that much pressure in your exhaust system.
Clogged muffler? exh pipe too small in diameter?
I was told by a diesel mechanic any point down stream of the turbo !!
Quote from: sledhead on November 20, 2011, 05:19:10 PM
I was told by a diesel mechanic any point down stream of the turbo !!
You need another mechanic!!!!
TOM
Quote from: sledhead on November 20, 2011, 05:19:10 PM
I was told by a diesel mechanic any point down stream of the turbo !!
he meant downstream on the fresh air side, not the exhaust side.
Mr. Sledhead sir:
Definitely NOT the right place to measure the turbo boost.
But one more question, supposing it WAS in the right place: What size wiring are you using between the engine compartment and the dash? If you are running 40-50 feet of wire, and using small-guage wire, you might get a tremendous voltage drop and not an accurate measurement.
Top mounted turbo on a 6v92t has a plug on each side of the air horn to hook a gauge up you are not talking about a electric gauge right,use 1/4 tubing to the dash instead of the 1/8 inch it will read 20 lbs under load +or -
good luck
One of those plugs on the exhaust side should take a pyrometer sending sensor, if I am not mistaken. (That is exhaust temperature.)
The exhaust gas pyrometer goes before the turbo. Exhaust gas inlet temperature. Too high=new turbo.
Could anyone post a photo showing those plugs please
Plug on hot side would be for pyrometer thermocouple.
do not know where to look for a plug ,found 2 plugs below turbo on I think the blower ,1 left side,1 right side ? 1/4 " ,I have a 1/4 " air line from back to front and a boost gage thanks dave
Those are the plugs either side will work
good luck
to remove the plug it looks like a 1/4 "extenion will fit, will rust ,crap fall in ? and is it better on hot side or cold side thanks dave
Clean it before removing the plug it has to be connected between the blower and the turbo the horn bolts on to the top of the blower it is not really part of the blower install there and the gauge will work
good luck
I feal like a dummy . tried left and right came off with no problems. hot side is the easy side to hook it up to , just need 3/8 " to 1/4 " adp.
Quote from: Brassman on November 20, 2011, 09:16:16 PM
The exhaust gas pyrometer goes before the turbo. Exhaust gas inlet temperature. Too high=new turbo.
a EGT guage goes after the turbo, not before.
Not entirely true Eric some DD's have probe taps on both manifolds for the EGT gauge fwiw
good luck
Ive never saw one before. Thats new to me but I havent been around dd to much either.
It is better on the exhaust side of the turbo those little probes can cause a mess when they brake off and get into the turbo
good luck
Why would one want to know the temperature after the turbo? Granted, my experience is marine, and with larger engines, but how hot the tailpipe gas is, is info you don't need.
Gets pretty hot there. Also try to mount the boost sensor as close to the blower as possible as it will give you a more accurate reading on the amount of boost going into the engine. And...if you want toos, mounting an intake air pyrometer sensor next to it will let you gage your intercooler intake air temp. Cooler is better. HB of CJ (old coot)
So, to prove myself right I did some internet searching. The temperature you want is the turbine inlet temperature, and as luvrbus posted, some manufactures do indeed recommend the probe be placed after the turbo--to prevent damage if the probe fails (just as luvrbus said.)
I guess you infer the turbo inlet temp.
thanks for the help . installed in the right spot (hot side ) works great 23-25 lbs under load . thanks again dave
On all trucks I've seen (and I've seen alot since I sell them) the turbo heat sensor is always after the turbo. Mainly-sometimes the sensor bulb will break off they don't want it going through and destroying the turbo. The only time I've seen sensors before the turbo were on really big Diesels. I saw 4 Wartsilla 8 cylinder engines used to generate electricity on the island of Kauai in Hawaii. They had individual pyrometers (exhaust gas temp) on each cylinder, along with overall exhaust temp before and after the turbo-and a tachometer on the turbo.
On a 2 stroke engine, exhaust temp is really not needed-they flow so much air that exhaust temp rarely will get above 900 degrees. Now if you have a big injector engine-that's different-I mean a 90 injector 71 series or a 110 injector 92 series. Good Luck, TomC
Regarding the before or after the turbo position for EGT sensors, think about it this way- it really doesn't matter from the standpoint of telling what your engine is doing. What matters is what your engine is doing right now, vs what it usuallly does under similar circumstances. Absolute temperatures don't mean a thing- well to some engineering types they do but the reality is that you're using the gauge to compare current engine operating conditions to a baseline. For that, it makes no difference where you place the sensor, just like it makes no difference what is printed on the gauge... it could be 500 to 1500 degrees, and it could just as easily be A through Z, with some red paint where the danger zone is in either case. It's all about comparing what's happening right now to what usually happens... when you see a difference, no matter where the sensor is or what the scale reads, you know something's going on that might need your further attention.
That said, the argument to place the sensor after the turbo due to possible breakage is the smartest of the choices. It'd be stupid to trash a $2000 turbo for a $10 broken probe!!
And sled head, I still want to know what's making your exhaust system have a 5PSI back pressure! Seems a bit much....
when I had the boost pressure pick up in the down pipe to the muffler. at full rpm gage was about 3-5 lbs . I gess back pressure from muffler dave
Tom C all that I have saw where after the turbo also. Most of what I have been around are pulling trucks (all cummins) and no one is going to risk a turbo with the money they have invested in them.
I will continue to put mine after the turbo on everything including my trucks. If you want to put it before the turbo go for it. IMO its a preference thing. Theres no 100% right or wrong way to do it.
Eric
I would do what the engine manufacture recommends. In my 35 years on the marine side never had, or heard of, a pyrometer probe let loose and trash the turbo. And yes, there where also pyrometers at every exhaust outlet, and that was even on '71's and cummins 855's, though it was next to impossible to keep them working, and they would eventually be pulled.
When setting engines in the tandem setup 2 engines running tied to 1 output the EGT reading are always taken before the turbo that is how equal power on both engines is achieved done that way on Cummins,Cat,DD or any diesel engine that is the way you set those not done by RPM only by EGT fwiw
good luck