long time no see.

[95MkViii]

hey guys been away for a while, looking at building a mark Viii engine to go into my new project. what with the stock lower end of a mark Viii engine handle???????? 400hp?!?! I know the rods are the weakest link, but need to know so i dont blow up a good block.

also to anyone that has done Mk Viii swaps what did you guys do for the P.A.Ts system?


thanks,

 

[chris2523]

yeah 400 or so, but any detonation at that level will start making windows.
so get a very good tune.

 

[Right on the Mark]

My #'s show 502 crank HP on stock engine. On nos of course. At your own risk. LOL Nawsss man

 

[chris2523]

yeah, 400 wheel, mid to high 400s crank.
something like that.

your own risk indeed. lol.

 

[ford nut]

P.A.T,s can be killed in the tune

 

[LaserSVT]

Hey mang, long time no see.

Your question does have various answers so I will go based off assumption. I will assume all bearings are new and properly gapped. I assume all bolts are properly torqued using proper lubes and various other assembly lubes. Assume the rings are gapped properly and are staggered.

So if its a perfectly health engine the crank can handle up to 700HP as has been proven in many Mustang GTs. The rods are a little tricky, positive displacement blowers are going to limit you to 400ish rwhp due to the low end torque. Centri or turbo and you should be good to 480ish. Nitrous is a fickle creature. If the car is tuned to perfection with cold plugs and timing ramped back you could see just over 500 assuming you don't hit the giggle juice too early.
Pistons are about the same. Reason they can handle more power with nitrous is it helps cool them so they don't expand as much and crack and seize.

That being said if the goal is for a street car on stock internals then I wouldn't push it past 400 rwhp. Also note that Coyote swaps in older Mustangs has caught on like wildfire and there are tons of forged 4.6 motors hitting craigslist for cheap. hell there is a Teksid block with a total 03/04 Termi setup on it all with 5k miles for only $4000 in Dallas.

 

[SouthernGemini]

What I did to my 5.4 Lightning Motor a few weeks ago. I put on a 6lb pulley and had a bigger cam but I was too hard on the accelerator. Approx 2 inch hole in drivers side of block. I still managed to make it home and I was over a mile away from home when it happened.

 

[Don Pfau]

I've been lucky with mine at 4 years and at least 5,000 mile. I expected it to go a long time ago. I even have a very good back up engine but I just haven't needed it. We have checked it out regularly and compression has been even, good, and consistent. No smoke or rattles. Everything checks good.