I plan on running Nitrous with an RPM activated window switch and need to know what RPM I shift at so I can shut it off 100 RPMs before.

What is the normal WOT shift RPM for it?
Can it be set any higher without hurting anything?

I have a 99 F-150 with a 5.4 and the 4r70.

Thanks,
Mike

 

Hi Mike,

In short, if that 5.4 has NO performance modifications whatsoever, then you can use a *maximum* of a 50 HP shot of nitrous on the stock fuel pump - in the 4.6's, you can use a 75 HP shot. This is due to numerous factors, such as the stock 19# injectors have a maximum HP capacity of just 310 HP (and that's in naturally aspirated trim), the fuel pump has a similar limitation, as well as the fact that the stock cast pistons cannot tolerate big peaks in cylinder pressure and the 4R70W automatic tranny can't take a big shot of nitrous in stock trim - at least, not for long.

I'd say forget using the typical 100-150 HP shot of nitrous on your truck that most street kits provide, unless you do some upgrades to the tranny and the fuel pump, at a bare minimum.

When using nitrous in the F-150, we do not recommend upping the shift points over stock in the stock 5.4 motor, as it has a sub-optimal rod/stroke ratio due to it's 4"+ stroke and almost 7" long connecting rods (which is why it has a forged steel crankshaft), and of course the 4R70W is not a particularly strong tranny for use in heavy trucks when huffing big shots of nitrous - it may take it for a while, but sooner or later, it will usually fail with a lot of NO2 use.

Now setting aside the powertrain's service life, for absolute quickest acceleration you would use a 1-2 WOT shift point of 5600 rpm, the 2-3 at 5400 rpm, and the 3-4 at about 5000-5200 rpm in these heavy trucks.

Used properly, nitrous can be safe & a lot of fun to make more power, but you just have to know the limitations of the individual vehicle - and in the case of these F-150's I would not depend on all the various NO2 kit manufacturers claims 100% - some just push things too far, so please be careful.

Yes, a properly designed nitrous kit will augment the fuel delivery capacity of the *injectors*, but that doesn't give you any more *fuel pump* capacity - many NO2 kits do not address the fuel pump at all. Also, don't do something dumb like install a part that increases the stock fuel pump's output by increasing voltage - like a "Boost-a-Pump" or other similar devices - the only way to properly increase fuel pump capacity is to install a larger fuel pump, which is cheap & easy to do. A 190 l/hr Walbro fuel pump is under $100 *including* installation kit, and it's a relatively easy install.

There is no set "normal" WOT upshift point in the non-Lightning F-150's - in some trucks the 1-2 is as low as 4600-4800 rpm, while in others it's as high as 5350 rpm - it just depends on that vehicle's computer code from the factory and what Ford programmed into it, combined with just how quickly each tranny can fill the oncoming clutch, which can vary - you can take 10 *identical* F-150's and have 10 different WOT upshift points for each gear change, literally - thus there is no one set "normal" WOT upshift point for a 5.4 F-150 with a 4R70W automatic, for example.

I would suggest giving us a call at our number listed below and I can tell you how to find your truck's computer code, and then I can go thru it's program with you to let you know it's actual upshift point commands, etc. - and if you like, give you some advice as to how to set up your nitrous kit and any other mods you may have or may be considering, as we specialize in modifying these F-150 platform vehicles for more performance.

Best of luck whatever you decide, I hope it works out well for you!

 

I damaged my 4.6l engine w/ a 100 shot of nitrous. It was way too much for my stock fuel pump and I wasn't smart enough to hurry up and get my new fuel pump in the truck which I had sitting there.

I've already spoken to Mike several times about my problems and he has been a great help. Listen to what he has to say!!!

If I had to do it again, then I'd upgrade the fuel pump right away, use a dry shot of nitrous so I don't have any fear of fuel puddlinging or a nitrous backfire, and upgrade my fuel injectors so I get the right amount of fuel. Nitrous is a lot of fun but do it right or it will end up costing you a lot of money... like a new motor!

 

Hi Intel486,

Nice to see you drop by.,...this must be David O. - I mention that just because I think you called a few days ago, and I hadn't had a chance to return your call just yet - we've had 2 big snow/ice storm events, and we lost power and some expensive hardware as a result, and that's kept us pretty busy, my apologies!

I'll try to get a call in to you this afternoon, if possible.........

Thanks very much for posting your experience with shooting the 100 HP shot of NO2 - the stock fuel pump is indeed an issue, and of course, tuning for nitrous can also be an issue. Now in your case, by now you have already taken care of the fuel pump upgrade, and are also working on the new motor - which sounds like it's going to be a killer that you'll really be able to lean on hard.

Many NO2 manufacturers will say it's OK to run on the stock program & fuel pump, and while that is indeed the truth with some vehicles, you just can't do that in these trucks & SUV's - we've seen too much engine damage just from not enough fuel pump capacity. One thing some people are not aware of is that this will still happen even if you've got a custom nitrous tune! The stock fuel pump *must* be upgraded in these non-Lightning trucks to use nitrous safely, unless it's a basically stock vehicle and the amount of nitrous used is very small - in short, we prefer to see anyone using nitrous upgrade the fuel pump.

The stock fuel pump in the 1999 & up V8 trucks (not including the factory-supercharged Lightnings & Harleys) can support a total horsepower level of about 310 to perhaps 330 - we call it 310 HP at the most to be safe - and that's at the *flywheel*, not at the rear wheels - for those of you who go to a dyno, this is very important to remember!

For those who have been to a dyno, for a 2WD truck w/4R70W automatic, you lose 65 HP to driveline losses, so add 65 HP to your rear wheel power numbers to get your flywheel HP number - for 4WD's add another 5 HP for a 70 HP driveline loss. For those with 4R100 automatics, in 2WD the loss is 70 HP, with 4WD it's 75-77 HP. And for those of you with manual transmissions that are 2WD, figure your driveline loss at 35-38 HP, another 5-7 HP with 4WD. (Also, once you add a lot of power gain, you will see a little bit larger loss in HP to the rear wheels - another 75-100 HP added to a Lightning can cost you another 5+ HP in total losses.)

*Never* rely on any set percentage to calculate driveline losses, as the exact same transmission will see a much different percentage of loss depending on whether it's a 4.2 V6, a 4.6 V8, or a 5.4 V8 - meaning, depending on it's power level, basically. For example, a 4.2 V6 is rated at 205 HP, with an automatic it will lose 65 HP, for a rear wheel stock number of (at best) about 140 HP stock - well, that 65 HP loss is 31.7% of it's 205 HP stock rated. Now if it's a 4.6 motor, it has the same driveline loss (approximately), but that 65 HP loss now represents a 28.14% loss in the 2001 & up 231 HP 4.6 - and if it's a '99-'03 260 HP 5.4 motor, that 65 HP loss is just 25% of it's 260 HP SAE Net stock rating at the flywheel - so don't use percentages, use the actual HP loss - the only way to know driveline loss is to do a drag-down test on a chassis dyno - we've done that countless times with these vehicles, so we know the losses very well, and thus can offer the above numbers & suggestions, etc.

Thanks for your post David, & talk to you soon!

 

Thanks Mike! Was good to get to talk to you today.

Ford Rulez All, like I said before, listen to Mike, he knows his stuff. He warned me about the 100 shot and I didn't listen and look where it got me... I'm gonna need a new engine and I can barely even drive my truck right now.

 

Thanks for the info guys. I am going to be installing a walbro 255 pump now with the kit. I will probably only spray 100 shot on the motor and do it very rarely. I also know the trans will most likely blow because the truck is already on its second one with only 27k. Once I do the nitrous I will most likely look into a fully built 4R70W.

Do I need a nitrous programed chip to run nitrous? I was told as long as my timming is stock I would be ok. Also I plan on running NGK TR6s.

Thanks again,

Mike

 

Hi Mike,

Well, that really depends on the computer code of your individual truck to a certain extent, as some of them have more timing than others in terms of what actually gets delivered to the motor - it wouldn't be a bad idea to do a quick datalog to see just how much timing it's showing @ WOT thru the entire rpm range, and also in as many gears as you can get - in other words, not just 1st & 2nd gear, but also up to as high a speed as you can safely get to in 3rd gear too, without having an accident or getting a ticket - preferably all the way up to as many rpms as it will pull in 3rd gear, even redline if it could get there (and it won't pull redline even in 3rd without some mods).

Also, remember that you *have* to have a chip/tune in order to defeat the top speed limiter, which kicks in usually around 98 mph or so - even with nitrous, or 1000 horsepower, literally - on the stock factory program you won't get any faster than about 98 mph or so without having the torque limiters, speed limiters & shaft speed limiters *all* removed. So I would plan on needing a custom program to do that with, as otherwise, you will have to be *very* careful, as once the speed limiter kicks in, you could potentially have a nitrous backfire from it kicking in while @ WOT & spraying the NO2 - so if you use it on the stock program, make sure you turn it back off (via the master arm/disarm switch in the cabin) once you show about 90 mph on the speedo, just to be safe.

And if you want to use nitrous at more than 90 mph, then you'll need to have a custom tune done - and I'd highly recommend that anyway, before you spray *any* nitrous.

Yes, on many vehicles it can be used on the stock factory program, but in these vehicles you have to be careful - if you try that, do that only with the best pump premium (preferably 93 octane, but at least 91 for those out West) gas, and then cut it back off once yo hit about 90 mph, and that may work OK for you.

Use *only* copper spark plugs (no platinum plugs with nitrous, and not even the Denso Iridium when spraying 100 HP shot or more, to make the ignition system's job easier) - make sure you are 1 *full* heat range down from stock, bare minimum - the TR55 is equal to the stock level, the TR6 is about a half-step colder (some call it a full step colder), so you could do that with a 50 or 75 HP shot - I would make sure to be a full range colder with a 100 HP shot. Also, make sure to set the gap at not any larger than .032 with the stock ignition, and you may find you need to go down to .028 so it will fire cleanly & pull hard once you get up into higher rpms in 3rd gear, for example. the stock COP ignition is not the best, and once you start adding significant cylinder pressure, it needs help.

Last, I would not use this forum as a substitute for proper consultation with a qualified F-150 tuner - work with a good F-150 tuner so you know you have the best chance of being "safe" with the nitrous is your best bet. Of course this is up to you - I just don't want to see any potentially avoidable problems happen, you know what I mean....

Glad you're going with the 255 Walbro, that will be plenty of fuel pump, then just make sure whatever nitrous setup you use can deliver enough additional fuel rail pressure to the stock 19# injectors so you don't go lean - remember, the stock injectors at stock rail pressure can only support about 310 HP! Most good kits give some way to augment fuel rail pressure/fuel delivery.

Have fun,