I'm so thrilled I can actually add real data to the large collection of data on this board. I had Autometer Boost and Oil Pressure gauges mounted this past Tuesday at Helix. I got the SPI gauge pod by SPI Power Accel, I believe. These are the guys builidng that twin-charged MCS.

Boost - all readings were taken at temps between 85-95 degrees and high humidity

Normal idle = -24lbs

idle A/C on = -10lbs

Max Boost = +16lbs

Max Boost at 3k RPMs = +11lbs

The most amazing thing, IMO, is that I get the same boost at 3k RPMs in the hot, humid weather than the stock gets at redline with much milder temps.


Oil Pressure

Idle after startup = 60-70psi

Idle when warm = 40psi

Idle when hot = 20-22psi

Hard driving = 60-80psi

Typical cruising cold-warm = 60-70psi

Typical crusing when warm = 50-60psi

My pressure readings are higher than what Andy had reported https://www.northamericanmotoring.co...t=oil+pressure. One reason is probably b/c I use Mobil One 15w-50 High Performance Driving Formula while he uses Mobil One's 5w-30.

As far as power mods go, I have the 19% pulley, UUC exhaust and Madness Intake. I'm quite pleased with the boost numbers since they were taken on very hot, humid days and I have quite the free-flowing exhaust with the UUC. I imagine I'd get at least another pound of boost in cooler weather - maybe more!

Bottom line, I never thought gauges were really worth the money but I feel like I wasted the last 49k miles driving without them. They look absolutely amazing and I love the extra info they provide. I was quite surprised to see how quickly the boost bypass valve closes on its own. You can go from
-20lbs of boost to +11lbs in a blink of the eye or the time it takes to slam down the accelerator.

I will post pics soon!

 

Regarding cooler air; in my Stealth Twin Turbo I have 14.5 lbs of boost dialed in with a manual boost controller (summer time), but as the seasons change, and it gets cooler out, I easily see a 1 lb increase. That is pretty common result with other guys in that group. I'd assume the supercharged cars would react as you mentioned with colder air.

Same reason larger intercoolers are usually sought out.

 

good info.
I see as low as 11lbs oil pressure when hot. Mobil 1 5w-30.

 

The grounding of my oil pressure sender isn't correct, so I suspect that explains my very low readings at hot idle. When I fix that grounding, I'll report back.

 

what are the boost numbers for a stock MCS?

is it 11 lbs as greatgro alluded to?

just curious.
all i know is that my 19% made a huge difference in lower end (2500 rpm) torque. - as it should have been from the dealer.

 

 

I thought I was getting boost around 16 with my 15% pulley, now I'm not sure the gauge is accurate. It still has a peak in memory of just under 17, yet when I data log with my CarChip E/X, its recordings (every 5 seconds) have shown highs around 25.5 to 26 - absolute as Andy shared with me a few weeks back.

Factoring-in psi at sea level (I'm in the Bay Area), then that would equate to around 11 or 12 pound of added SC boost. Yet, a drive last night had the boost gauge red warning light go off a few times; it's set at 14. A download of data revealed, again, around 25 absolute psi...

Note:

Since my data-logger is only capturing every 5 seconds, there is a possibility that I'm seeing higher highs between those intervals. I have done up to 70 trips now though, with 26 as a high...

Are boost figures impacted by where, or how the data is captured? And lastly, a theoretical question. By adding a boost gauge, is one actually adding to the volume of the system thus decreasing boost, albeit minimally?

Just wanted to share some of my "research," and solicit some input back... Thanks.

 

I was sort of hoping folks would chime-in...

I chatted with one of our tuners, and he too thinks that our boost readings are fishy. He has seen absolutes of around 28.5 to 29 psi. Accounting for atmospheric conditions, and that's around 14 pounds with a 15% pulley...

Mechanical gauges apparently can be a little off sometimes if the in car temps are high. I have an electrical one though...

Just wanted to share...

 

I've recorded peak boost of about 2050 mbar absolute using the 15% pulley at 6950 rpm. This is at an elevation of about 300 feet (basically sea level) with an ambient pressure about 1010 mbar. I'd suspect that folks at higher elevations would see significantly lower absolute pressures.

 

Thank you Andy. Are you getting that data via logging from the MINI, or are you using some type of gauge that is independent of what the MINI is recording? A couple pounds of boost is fairly noteworthy. I appreciate your response and knowledge on the subject! Thanks.

 

That's what I have seen from the MINI's diagnostic system. I also have an Omori mechanical boost gauge plumbed into the vacuum line to the FPR. It peaks about 15 psi at redline (it happens so fast that it's hard to get more accurate than that )

 

tony, fwiw i think that boost spikes are reasonable to assume. you have to keep in mind that there are a lot of factors that control boost pressure including relative and absolute humidity, temperature both ambient and at the IC. and an accurate ambient air pressure reading where you are testing. elevation affects air pressure but the weather does as well.

andy has already shown that an intake makes a difference in flow and "negative" air pressure at the throttle body, in the HAI thread. one would assume that it translates further down the intake line.

add to that calibration issues regarding readings both mechanical and electronic, placement of sensors and other things, a couple of pounds difference would easily be seen.

i wouldn't beat yourself over the head trying to find the last two pounds. you probably already have them

 

olYeller, the variables are many, and I guess that is probably the reason for the deltas. I suppose I can't expect my MINI's accounting to jive with that of my gauge then...

Since there are different types of gauges, it might be more accurate to see/compare data logs of intake manifold pressures - for comparable elevations and atmospheric conditions.

Thanks Andy for the clarification.

 

think of this thread as a conglomeration of data then. your input is very valuable and may give someone an idea or at least a starting point for testing of their own. if you can clarify some of your variables then it gives folks a reference point for their own testing.:smile:

 

Dude - I am so happy that I found your post.

I just installed the Promini boost and oil pressure gauges yesterday and notcied around 50psi oil pressure while cruising along on the highway at 65mph.

This morning I took it out for a spin and noticed that the pressure dropped to 12.5psi at idle after a few minutes of driving and I started to freak out. I thought perhaps I had a leak or something but then I also noticed that it was steady.

Phew.

I have stock Castrol 5W-30.

 

I finished the installation of a Mini Madness Oil cooler and below is the oil pressure data I have collected.. I am actually trying to figure out if adding an oil cooler will lower the oil pressure due to the added travel and additional oil amount...

Anyways, here's my data.. Haven't driven it too hard yet, but if I floor my gas, it seems that I don't pass the 61 psi mark (this is rolling "flooring" , 4th/5th/6th gear) not from a stand still.... I did see it reach 70 psi when engine was relatively cold and I tried to punch it a little bit on first.. But overall, it doesn't seem to be passing 61...

What would be a bad oil pressure number????

==== DATA =====

Idle right after startup = 60
Idle when hot = 19-21 psi


5th gear
4,000 RPM 55 psi
5,000 RPM 61 psi

6th gear
2,000 RPM 38 psi
3,000 RPM 52 psi
4,000 RPM 60 psi

==========

Thanks

///Gilbert

 

oil pressure:
idle at startup: 55-60
after warm-up: 15-20
constant 70 mph: 40-50kpa

boost:
idle: 0.6-0.5 vaccum
WOT: topped out 1.1 bar
6th gear crusing at 70 mph: 0.3-0.1 vaccum
with A/C on at idle moves to 0.4

 

the pressure (and temp) will vary depending on where you meaure; with the oil cooler setup, another variable is if it is full flow.


I measure oil temp at the exit side of the filter assembly where the oil is just heading into the gallery. It just came from the pump and filter and represents a pretty good measure of steady state temp. If you are reading temp at the oil drain plug, I would expect temps to be a tiny bit cooler (5 degrees?) as the pan is a heat sink giving heat to the air and cooling the oil. If you have the remote oil cooler, it might be different as well.

as far as pressure changes. I don't think the volume of oil would be a factor, however, the location of the coller and the plumbing sizes and layout are factors. The point of the pressure is to maintain the oil wedge in the main and rod bearings, so that is where you wnat to see 60+psi under load. On my short block project, Endyn chose to re-work my oil pump to improve flow and raise the bypass pressure and to smooth out the oil passages. I haven't put it together yet.