Does anybody know about the internal strenght of the 4.6 triton V8? How many rpms can the stock engine handle? Are the pistons strong enough to handle a 100hp nos kit? I'm planning to put a 100hp wet nitrous kit and a little concerned about my engine over reving.

I have a 1999 F150 4.6 4x4 lariat with 3.55 LSD and automatic transmission. For some reason when i flatten the accelerator my automatic transimssion will automatically change into second gear at 5000rpm. Is this normal? Appreciate any replies.

 

100 shot is a lot, I know that...and as far as reving, I don't think the PCM will allow the engine to rev higher than its redline anyway. How high an engine can rev is more about the stroke of an engine rather than the internal strength. A diesel with a really long stroke may only rev to 4k for example, but a new sports car motor with a short stroke may rev to 11k...which is stronger internally?

 

5000 rpm sounds intense. I don’t think that right. I reprogrammed my engine and only let the rpm get to 3000 in first gear. I know this guy that owns a truck shop and drag races pro stock, he told me that a 65hp shot of nos would be risky. From what I’m told, it can depend on the mileage that you’re at. If you have a huge shot of nos on a high mileage truck, then you will blow the engine.

 

FORD went from forged to hypertec pistons in 93 which are cheaper and weeker.Strokers do not last as long or rev as high as shorter stroke motors simply do to physics.A 5000 rpm kick down into second at WOT is normal on the 4.6 or at least thats what ford says and all three of my trucks do it unless of course the floor mat is in the way.

 

To answer your question about the down shift at wide open throttle. Yes it is normal. Every vehicle, with an automatic, that I've ever had or wrenched on down shifts at wide open throttle.

Doug

 

the 4.6 will handle about 375-380 to the wheels. u can push it to around 400 but it wont last long being as there is more stress on the engine because its pushing more weight with the truck than on a mustang. with mustangs they usually can get 420rwhp and any more and stuff starts to break. but yes it will handle a 100, 150 wetshot.

 

and as for shifting the 4.6 can handle many more revs than the 5.4 can just by design. but safe is 5800. u can get a windage tray for it though and it will rev to about 6400 safely and make more hp.

 

Rev limiter is 5500ish on the '97. Course runnin' an M5OD-R2 lets me bounce off it all the time.

Adrianspeeder

 

Thank you to all that replied. It is quite difficult to find reliable information on the 1999 4.6 Triton V8. I have searched through the internet until I got sore eyes (4hrs or more) and could'nt really find much information on the internal structure. I believe it has a 5 bolt mains, am I correct? The pistons are hypo and supposed to be better than cast, but not as good as forged. I think the block is cast iron and head are aluminium. Are there any other weak areas of this engine that I should be aware of? Appreciate any replies. Thanks again.

 

cam journals dont have bearings. fyi.
from my understanding the mains are really stout.
my opinion on this is just that you better up to forged bottom end if yer gonna play with some big power or big shots of it.