The differential should be fine unless you spin one tire. It's not the load of high hp that kills differentials, it's spinning one tire.
Think about it this way. When you do a one wheel burnout you're only spinning one side. The speedo is driven by the spinning differential, so that means that if the speedo reads 60mph (redline in 1st), then the one tire is actually going 120mph (one side stopped, one side going). Inside the differential, the one side gear is stopped and the differential turning at 60mph is spinning the other side gear at double that speed. If the side gear is going 120mph, it means that the spider gear pinions are going about 300mph. This is simply too fast for them to spin on their support shafts. The get hot, the shafts expand and the spider gear seizes to the shaft. This causes the shaft to spin and it shears the roll pin that holds the shaft into the differential case. After you've finished that smokey one-wheeled burnout, everything seems fine. But when everything cools down and the two pieces release from one another, the there's nothing to hold the pin in and "Out She Comes".
So my point is that it's not lots of hp that kills diffs, it's one wheel burnouts or the spinning of one wheel in relation to the other.
The Quaiffe differential is a Torsen style diff. It has a preloaded clutch system and side gears that are driven by worm gears instead of bevel gears. It's a much stronger unit than the stocker. It's also a Limited Slip type differential. We have them in stock for those that need them. We also have the overhaul parts and even complete transmissions....again for those that might need them.
Now about the nitrous. As most of you know, I'm an old nitrous ******. These engines will take a ton of nitrous....if properly done. I was squeezing 150hp of juice in the car and ran a couple of seasons on the same set of plugs. Nitrous is rough on rod bearings and the rings. The bearings take a ton of load as the nitrous increases the torque. The rings have to seal all the additional pressure and keep it in the combustion chambers. The biggest problem with running the bottle is keeping enough fuel in the mix. Most of the time, you won't know it's leaning out until it gets so lean that you melt something. Also, most of the time you'll melt a spark plug and it'll simply drop the hole. This is why I advocate copper plugs. I like the plug to be the weakest link and the first thing that melts when things get too hot. I don't like to run colder plugs for the same reason. Platinum and euridium plugs will last longer when the going gets tough. This is especially bad in a case where the cylinder is leaning out, because the next thing to go is the exhaust valve. I've got SEVERAL examples of what happens when my setup was too lean and the plug survived (or kept firing even after it melted). The exhaust valves in these engines are small and don't transfer heat to the cylinder head very well (the exhaust seat and stem is how the heat is transferred - none of which is very big in these engines). When the valve gets too hot, it melts and gets cut like a torch. When this happens, you loose compression and drop a hole. It's an expensive and time consuming repair.
Lean is mean, but with nitrous, it's better to be too fat than too lean.
So the bottom line is that these engines are plenty capable of handling the biggest nitrous kit, you just have to do it right and have the proper respect for the equipment and what you're asking it to do.
