SOHC Nitrous Limit

[Broosedamoose]

I put a dry nitrous kit on my 07 Ranger 4.0 and I'm wondering about the bottom end. I read a few post that said the pistons were only good for up to 7-9 Lbs of boost. When I first tested it I started with the 25 Hp shot and worked up to the 100 Hp shot datalogging each time. I know the general rule of thumb is you can add a nitrous shot up to half of what Hp the engine makes on it's own. Since the SOHC makes 207 Hp that would mean a 100 Hp shot. However, when I tried the 100 Hp shot the fuel trims were a little lean. (1-3%) The stock fuel system is just not quite enough to keep up. I backed off to the 75 Hp shot and it was fine. But after reading the posts saying the pistons are only good for 7-9 Lbs of boot I wonder if the 75 Hp shot is too much. I don't really know how much boost it adds. I don't use it that much any more but I'm wondering if it's a ticking time bomb and I should drop to the 50 Hp shot.

 

[Blmpkn]

7lbs of boost would add roughly another 100hp to that motor, so I don't see why those pistons wouldn't be 'good' for a 100 shot.

 

[Roert42]

I think the biggest issue on the SOHC for boost is that the stock Compression ratio is pretty high. I think 9.7:1 from the factory, needs a knock sensor to run on 87. Running 7-9psi on stock pistons would need race gas or water/meth injection, I'm sure.

I'm not familiar with Nitrous, so I'm not sure how that effects everything.

 

[rubydist]

I think you will blow head gaskets before the bottom end, based on my experience with boost on that engine.

 

[Broosedamoose]

I think you will blow head gaskets before the bottom end, based on my experience with boost on that engine.

That was my initial thought. I think I feel comfortable with the 75Hp shot. Not much of a noticeable difference between the 75 and the 100 except on the time slip and it really needs a wet kit at that level. It's fun but she's also my daily driver and I don't want to blow something whether it be a head gasket or bottom end!