I did a quick experiment today to determine the difference in boost levels I'm getting between the 65mm and 61.9mm pulleys. Both runs were made within an hour on newly installed intake gaskets. I was a little surprised at the results. By the way, disregard the timing, as this is a nitrous tune, but I wasn't spraying. The temp was 72-75F on each run and the IAT's were almost identical.


65 mm - 16.7 psi
61.9 mm - 17.7 psi

Has anyone else logged a comparison? Also, check out the LTFT's. Not too shabby for running 550cc inejectors.

Here's the 65
65mmpulley_zps60882718.jpg



And here's the 61.9
619mmpulley_zps5c4c7ab3.jpg

 

Busy!! Have you noticed there's two "zones" of long term trims? On my display I can watch the trims change right before open loop. Or when cruising above 80mph. A slight decrease in fuel pressure may get you to perfect trims and a tune that sticks.

 

I've noticed the LTFT's changing at different times, so I just figured that different parts of the maps have different trims. In other words, at a certain pressure and rpm, the car may need -4%, while at a different area only -2%.

 

Tell me if I'm hyjacking this thread and I'll sit down and shut up.....

Interesting - sorry to sound so "newbie" to NOs but
- the NO2 is a liquid in the bottle yeh?
- so its very cold when injected (as a gas) yeh?
- you inject it where - before or after the MAP?
- how is the rate governed - ECU rpm link or simple manual setup under the hood and then take it for a test drive?

I'm just trying to understand why the increase in boost - pressure from the bottle shot?

Newbie thinking - if the volume is small and cold before the MAP, the pressure should go down due to the cooling effect, but the O2 content and density goes up more = more power.....

 

I spray it into my single NW intake a foot back from the filter. I have it activated by RPM via a window switch. I'm not sure scientifically why the boost readings go up when using it, but they do. If you do a google search on this, you'll see it's common (expected).

https://www.crossfireforum.org/forum...t-nitrous.html

IMG_20130203_165205_928_zps873ef61b.jpg

 

I can confirm your boost reading with the 62mm pulley. I'm at 17.7-17.9 under similar conditions. Makes sense that 65mm pulley would produce a bit less boost.
Log9-24-2013-1.jpg Photo by sukharevinn | Photobucket

 

Thanks for the info.

Log9-24-2013-1.jpg

 

Hi

It would be great if everybody who runs the smaller pulley could state there boost so that we know what the expected values should be for the different pulleys.

Please state both the Zeitronix boost reading and the odb map sensor readings.

EC 61mm(max boost):

MAP = 201.4kpa = 29.21PSI - 14.65(ATM) = 14.56PSI

ZT2 boost sensor: 15.95PSI

As you can see my max boost is 15.95psi which is very low. I do have a problem with my map sensor which for some reason gives me low ATM value.

The ATM pressure should be 29.21-15.95 = 13.26psi which is very low. My diagnostic tool says that the ATM pressure is unreasnoble low. Maybe that is why I get low boost value.
I will get a new map sensor this week and will be back with new test result.

What difference do you between the map sensor and the Zt2 boost sensor?

/Adam

 

I broke my boost sensor but from memory they are pretty close on my car. I've touched 19 psi at sea level with my 178 crank pulley and believe I was seeing mid 17's with my Code3. (65mm) I'll double check when I have access to the logs at home.

Les

 

An interesting study as I'm only seeing mid 17's as well... and that's on a GOOD day.

At least I know I don't have boost leaks...

 

13.26psi is about 870m (2,850ft) above sea level.
calc...
kPa atm = ( 101,325 * ( 1 - 2.25577 * 10^-5 * [ meters above sea level ] ) ^5.25588) / 1000
the ^ sign means "to the power of"
Siverarrow - Sweeden....you wouldnt be up at that altitude would you?

sorry - just to let you know - that equation gives you kPa
for psi & ft altitude use
psi atm = 0.0013 x [ ft altitude ] ^ 0.89

Between high and low pressure weather systems, air pressure deviates between 1030-990 hectopascals or millibar. So +/- 20 hPa = +/-0.3psi.
Unless you're in a cyclone/typhoon/huricane - and as die hard of a logger as you might be - you shouldn't be testing your boost pressure if your house roof is about to blow off....but undoubtedly some would like to disagree....;>)

 

I've been talking to Chris (LateModel21) about the boost levels we're seeing, and I guess 20PSI is the max we're going to get with the 61.9 EC pulley. I saw 18.8 PSI this morning (55F) at the top of 2nd, which would likely be approximately 19.8 PSI at the top of 3rd.

For some reason, I thought this pulley was going to make 22psi, but it's not.

Here's Chris' notes on the subject:

"Stock boost 14.5psig ("pounds per square inch gauge" ie, pressure ABOVE ambient) + 14.7 (air pressure above a vacuum at sea level .... ie "1 bar" aka "1 atmosphere")
= 29.2 psia ("pounds per square inch absolute" ie total pressure above a perfect vacuum)

29.2 psia x 73.6/61.9 (stock pulley diameter divided by new pulley diameter) = 34.7 psia

34.7 - 14.7 = 20 psig = 20 psi boost

so .... if your can generate 14.5 psi (psig) then changing the sc pulley from 73.6 mm to 61.9 mm should get you up to 20 psi. This is assuming pumping losses are the same ... these losses should however increase (as a percentage) as boost goes up so 19.5 seems reasonable"

 

Is 22PSI the max that ECU will accept without using the MAP clamp? I agree with you and Chris and already obtained a custom crank pulley 10mm larger than OEM. Just waiting for a new crank seal to arrive.

 

Be prepared to be bored......ZZZZzzzzz.....

So we're reading stock 74mm pulley = 14-14.5MAP
62mm = 17-18MAP

Obviously, you're increasing your cfm from nominal 607cfm stock to 'round 680 with a DCAI and 62mm pulley
- so all your pressure drops go up and counter some of your gains
- pressure drop is the square of velocity (or cfm if you keep your XArea/resistances area the same)

Intake Effects
On the 74mm stock pulley you've got 1.44psi drop through your [DCAI* + throttle body] and 620cfm
but that increases to 1.73psi with the 62mm since you're upping the ante to over 680cfm. That's -0.3psi

If you're on stock intakes (15" @ 445cfm care of NW)
you loose 2.03psi [intake+TB] with the 74mm
and 2.44psi with the 62mm or 0.7psi more than with the DCAI.

Intercooler Effects
I havent got any firm figures for the intercooler prs drop (yet) other than woody's 5" @ 250cfm for a clean IC . But we'll roll with that for now.
It's pressurised air post SC, so the cfm through the throttle body is almost halved.
Using his 5"@250cfm translates to a 0.63psi on your 74mm @ 620cfm and 0.67psi drop on your 62mm @680cfm. Not much here.....
However - going with Waldig's dirty intercooler (9"WG@~250cfm) that pushes the 0.67psi loss out to 1.20psi or 0.53psi lost due to a dirty intercooler!

Throttle Body Effects
I had a look at the 80mm and 82mm options some months ago as well as SL500 v Audi
Through that, it would appear the stock 74mm TB at Stock WOT air is rated for about 1 psi drop (607cfm) - that would be on the 74mm TB
Add the DCAI and get her breathing better and your cfm goes up to 620 and dP across the TB to 1.06psi.
note: That 1psi is included in the intake numbers above.
Going to your 62mm but keeping your 74mm TB - you up the air to 680cfm - and your losses go up to 1.28psi - so another 0.22psi lost here.
Going to the 80mm TB will gain you about 0.3psi and bring you back around or under the 1psi TB drop

blah...blah...blah.....
after going through all this - not sure it was that usefull, but I'm over it.

then of course there is SC eff., Vol.Eff. and of course leaks.....

 

That's way too deep for Friday after 4PM.

 

Yes, way too deep. Just give us the final answer.
But on a serious note, just shows the importance of data logging. There are way too many variations.

 

Hi

This is exactly what I was thinking about but I'm not a to good on how to calculate this.
I have the following:

- 90mm TB
- Needswings custom intake manifold
- Larger intercooler underneath the SC

Any idea on how to do an approximate calculation?

/Adam

 

Ok - more yawn factor.....
What I've tried to do below is show the effect of more cooling via a supercooler or similar that can keep your IAT's down to 122F at WOT. The present IC doesnt seem to be able to quite achieve this as I think was indicated by indicated by Boost Monkeys Ice tank tests, but assuming the rcompart + Waldig super cooler can.....you can note the difference in the last 2 sets of numbers. Same psi output from the MAP but very different rwhp numbers....
The first is for STOCK OEM, the 2nd, 3rd and 4th sets are with the DCAI

SC Pulley.... Final MAP.... Fuel input per injector..... lb/hr/injector..... Inlet Volume..... cooling..... cooling..... .....IAT C..... IAT F .....rwhp..... density
74mm..........14.5psi............ 447cc..161lphr........... 42.6................. 607cfm............-11.7kW/hr. -40kBTU/hr....50......... 122....... 290...... 2.15kg/m3
74................15.1............... 456.....164................. 43.4 .................619.................-12.7.......... -43...............50..........122 .......296...... 2.20
62................18.1............... 481.....173................. 45.8 .................654.................-11.9...........-41...............64......... 147 .......305...... 2.32
62................18.0............... 500.....180................. 47.6..................680.................-17.7.......... -60...............50......... 122 .......315...... 2.41

It would be good to log (and compare) density numbers rather than psi. That's the clincher!
I dont have a dashdaq or similar, but if you can pull in the MAP and the IAT it can be calculated.

PS - if you want to boast to your mates 400bhp - the 4th set does 396bhp....;>)
You can also see why the stock 450cc injectors are lacking with the 62mm, but the fuel pump may almost do it - if I could find some specs on the stock pump.....

 

Great, thanks for your reply. Just wondering:

- How did you get those numbers? OBD2?
- How do you measure the fuel input per injector?
- How do you measure the inlet volume? Is this value measured from the outlet of the SC?

What is the max CFM that the SC can blow?

/Adam

 

This should basically mean that even when I have 1.1bar in boost pressure the volume going in to the engine is larger vs stock. It would be great if we could measure the CFM so that we can compare boost vs CFM

/Adam