For those of you that have installed boost gauges, what numbers are you seeing?

Just put a boost gauge on my 2003 and I'm curious how my engine compares to anybody else's out there.

The car has the stock Eaton M112 S/C with the small Powerhouse (U.K.) pulley. So far, in three tests with about 100 miles of city, two-lane blacktop and Interstate highway driving at ambient temps of 45 - 60F degrees - WOT produces 14.5psi at best. Generally not over 13.8 psi before I have to upshift. No high gear, prolonged speed runs were made.

Sorry, I don't have any base line reference for the OEM pulley. What do ya think, are these numbers in line with what others are seeing?

Thanks.

 

With the stock pulley I generally see 12-13 psi and turning on the water adds 1-2psi. The most I have ever seen, on a cool day with the water running, was just a tick under 15 psi.

I have an electronic gauge, which means that it is an absolute pressure reading rather than being relative to ambient. I'm only at 1000ft so it isn't a big difference but it does change the result a little.

As an aside, I took the car for a baseline dyno a few weeks ago before starting more serious mods and got 333/333 at the rear wheels, so it seems I got lucky with a reasonably strong motor to start with.

 

When I had the Eaton supercharger I would get 21 psi on a cold day. I had the Eurotek lower pulley & 1.5 upper pulley along with a 3.5" fresh air intake setup & the blower had been ported as well.

 

Thanks guys, It looks like my engine may be at least close to being "in line" with what's normal. ccfulton I'm at 850' and running an electronic gauge too. 333hp at the wheels is pretty stout! I have a chassis dyno available to me just six blocks from where I work. I really ought to drop the $75 and make a few runs to see where I'm at.

JgaXkr It sounds like a S/C port work was a good investment in PSI, Huh?

I'm getting together the info I need to make an educated guess on jet sizing for a H20/meth system.

Any other peeps with some real PSI numbers?

 

Why not try a nitros injection rather than H2O/method..
It will cool the intake air as well. Double buble
IanP

 

Hey! At lunch today, I nailed it after coming out of a corner in second gear and she flat out buried me in the seat! I thought "where did THAT come from?" On the next safe straight I nailed it again and watched the boost gauge. Wow! 15.4psi for a moment.... I had not seen that high of reading in the four days of driving with the gauge. I was surprised, so I quickly checked the outside temperature. It was dry (for Missouri) and 43 degrees. About 5-10 degrees less than it has been.

I'm amazed at two things: First, at how much more powerful the car felt with only .9psi higher boost pressure and second, how much only 10 degrees less ambient temps affected the boost pressure.

It is interesting to have a few numbers to back up the seat of the pants feel.

And IanP I have a NO2 bottle and and two "wet" systems - a NOS "cheater" and a progressive NOS "big shot." But both are for square bore 4bbl carb cars and not for injected engines. I could explore dry Nitrous but I don't really want to risk that kind of power adder without bigger injectors and a LOT more control of the tune.

I realize this is a very deep and wide question but, are there suppliers offering a tuning program that would actually allow us to see and "tune" our Jag's ECU? I have seen one or two companies that supposedly can modify the tune of our engines - but they charge mega mega bucks for doing so. I don't really want a Mustang or an LS1 Camaro, but the support for tuning those powerplants and transmissions is just amazing!

Forever a tinkerer,

-Caractacus Potts

 

Quick question, where is the best place to plug in the boost gauge? (weekend project).

 

See pic. This is where I tapped into the manifold pressure. On the right rear corner on the S/C hat is a vacuum line that turns forward and goes to the fuel pressure sensor on the right fuel rail. I split the line there and put a tee in it.

 

I take it that you know that neighbourhood well?

 

Indeed!