Nitrous newb have a question regarding Nitrous and MAFs.

**ForceFed** · 04-23-2007, 12:10 PM

I'm thinking about going with a HSW dry shot kit. I'm wondering if it is possible to spray upstream of the MAF without doing any damage to the MAF itself?

**mrr23** · 04-23-2007, 01:35 PM

that's how it's done, on a LSx vehicle.

**Eagle** · 04-23-2007, 02:17 PM

Yep, on a dry kit the spray must travel thru the MAF so that the ECM can adjust fuel levels for you on the fly.

**TwistedSS** · 04-23-2007, 05:50 PM

Originally Posted by ForceFed

I'm thinking about going with a HSW dry shot kit. I'm wondering if it is possible to spray upstream of the MAF without doing any damage to the MAF itself?

Thats how a dry kit works. BTW Welcome ForceFed. You putting the gas on the 540?

**ForceFed** · 04-23-2007, 06:10 PM

Originally Posted by TwistedSS

Thats how a dry kit works. BTW Welcome ForceFed. You putting the gas on the 540?

Thanks to all for the replys! I am infact putting the bottle on the 540I!

Has anyone who has sprayed a dry kit upstream of the MAF ever reported any damage done to the MAF as a result of spraying nitrous? The reason I ask is because the Bosch MAF found on the E39 540Is and E39 M5s is not a very quality piece. It seems these cars tend to go through MAFs about every 25,000-40,000 miles. They're expensive to replace ($340) and when they do go bad, cause very poor fuel consumption, low/erratic idle and sever power loss, especially in the bottom end. I'm hoping that the use of nitrous will not accelerate the deterioration of my MAF which is why I posed the question in the first place.
I do know of several people running between a 75-100 wet shot on 540Is on stock injectors so I think I should have enough fuel for a 50-55hp dry shot. I have a friend who has a intake/short throw shifter and 55HP shot 540I that trapped 109mph so I'm hoping I can expect the same kind of results from mine!

**mrr23** · 04-23-2007, 06:18 PM

can you not plumb into the fuel rail for a wet kit?

**Eugenio_SS** · 04-24-2007, 05:17 AM

depends what's the cause of the MAFs going bad.
if it's due to heat... the nitrous will actually extend its life.
note that if you were to put the nitrous too close to the MAF you could freeze the MAF and make inoperable until it thaws.
given the MAF fragility, i'd strongly consider a wet-kit instead...
Regardless of the approach (wet vs dry), you have to make sure the fuel pump can take the extra demand. If you go dry, you also have to make sure the injectors can distribute the extra needed fuel. Wet system bypasses the injectors, going through the fuel solenoid.
Regar

**ForceFed** · 04-24-2007, 05:42 AM

Originally Posted by mrr23

can you not plumb into the fuel rail for a wet kit?

To be perfectly honest with you, I haven't even looked into whats involved with where to tap into for fuel simply because I was hoping I could get away with the simplicity of the dry kit.

Originally Posted by Eugenio_SS

depends what's the cause of the MAFs going bad.
if it's due to heat... the nitrous will actually extend its life.
note that if you were to put the nitrous too close to the MAF you could freeze the MAF and make inoperable until it thaws.
given the MAF fragility, i'd strongly consider a wet-kit instead...
Regardless of the approach (wet vs dry), you have to make sure the fuel pump can take the extra demand. If you go dry, you also have to make sure the injectors can distribute the extra needed fuel. Wet system bypasses the injectors, going through the fuel solenoid.
Regar

I didn't think about the whole MAF potentially being frozen-thing. Below is a pic of where I was planning on putting the nitrous dry nozzle in relation to the MAF. Would this be considered too close?

You guys are definetly the nitrous experts and if you don't think the dry shot kit is a good idea, then i'll look into the wet shot. I was hoping to go dry simply because of it's simplicity but if that could cause problems then i'll reconsider it.

**Eagle** · 04-24-2007, 06:46 AM

IMO wet is the better route to go because you dont have to rely on your injectors to be able to deliver the fuel required to get the proper A/F ratio. A fuel pressure safety switch is a great add on to a kit if you're concerned that your pump may not be able to support the additional load. This way when you do hit the button, you're sure that your A/F is dead nuts and therefore have a safer system on your hands.

On that same note, if the MAFs are known to freak out from time to time, I'd really consider going the wet route so that if the MAF reads wrong while you're spraying, chances are reduced that your shot will will damage your motor.

As for putting the dry kit thru your MAF, folks here do it all the time with GM MAFs. What it will do to your BMW MAF, I can't say. But with the smaller shot you said you were using, I'd be willing to bet that you'd be OK putting it right where you have it in that pic.

-Eagle

**Eugenio_SS** · 04-24-2007, 08:41 AM

it would not be too close, imho.
i'd still go wet.

**ForceFed** · 04-24-2007, 10:41 AM

Great info guys, i'm learning alot here. You guys are A+! I'm going to ask the 540 guys who are spraying a wet shot where they are tapping into to get their source for fuel. If its relatively easy to get to it then I may just go the wet route. Otherwise I think i'll go 50-55hp dry shot and do a hail mary before I go WOT

**Airguy** · 04-25-2007, 12:00 AM

I have only used wet kits, but i put my nozzle after the mass air meter and never had any problems. Should I be spraying before the meter, just wondering?

**Eagle** · 04-25-2007, 07:06 AM

If you use a wet kit, it should be AFTER the MAF, otherwise it'll try to adjust for the additional volume it sees therefore running your motor rich.

**LS2Tuner** · 04-25-2007, 08:04 AM

I would also vote for the wet kit on the 540. I have done a couple of installs on other BMWs before. You can safely blow 75-100 without any problems.

The key is to get the A/F ratio correct and installing colder plugs aided with detonation.
I can tell you first hand that there stock clutches DON'T like the added TQ. The last one I did smoked the clutch in 2 days on a 100 shot.
They put the pressure plate pressure soooo light for creature comfort.
Have you purchased ANY type of extended warr.?

**ForceFed** · 04-25-2007, 09:32 AM

Originally Posted by LS2Tuner

I would also vote for the wet kit on the 540. I have done a couple of installs on other BMWs before. You can safely blow 75-100 without any problems.

The key is to get the A/F ratio correct and installing colder plugs aided with detonation.
I can tell you first hand that there stock clutches DON'T like the added TQ. The last one I did smoked the clutch in 2 days on a 100 shot.
They put the pressure plate pressure soooo light for creature comfort.
Have you purchased ANY type of extended warr.?

LOL no I don't have an extended warranty. The 540 clutches are actually pretty stout. Some of the supercharged 540 guys are running OEM clutches and putting down between 330-350RWHP on the stock clutches. I think its the higher mileage ones that still have the Clutch Delay Valve in place that might be slipping?
I think I'm just going to go with the wet shot and probably just spray a 50-55 shot and go from there. We'll see if my clutch will hold it. I have deleted the CDV and I frequently bleed the clutch to try and extend the life of it so i'm hoping it will hold the 50 shot.

Any recommendations on the fuel jet to start out with? I'll probably go with the HSW wet shot kit.

**LS2Tuner** · 06-22-2008, 09:09 AM

**ForceFed** · 06-22-2008, 06:58 PM

Ok.
I just replaced the clutch with an OEM M5 clutch. Should hold approximately ~440-ish HP. The car now has 164kmi on it but i'm going to spray it.

Right after I fix the broken sunroof, replace the excessively worn tires, replace the front upper control arms and bushings, replace rear ball-joints and carrier bearing, thrust arms, shocks/struts at all 4 corners, 1.25" drop springs, new brakes all the way around, post-MAF vacuum leak from injector O-ring seals, Intake manifold gasket, CCV...

Don't ever own a E39 540I. They'll nickel and dime you to death.

bmw 540I---->

<-----me