The folks with old XKRs and twin screw blowers are reporting over 600 HP and are clearly driving their 15 year or so cars with 4.0 or 4.2 engines like mad men. They do typically change out the rear end but that is because these older cars don't have limited slip differentials which means they tend to sit and fry one tire when you jump on them. Apparently putting all that power to one wheel is only good for spectacularly long single wheel burnouts. It is a tempting change because the twin screw generates far less heat than the Eaton so you can get more compression. They push upwards of 20lbs without a tune though they do radically change the intake and often increase the size of the injectors. So the 5.0 with far beefier components should at least do as well.


Here is one of them: https://www.jaguarforums.com/forum/x...n-screw-96101/

 

Thanks for the info. I thought the 4.2 had all forged internals and the 5.0 has a cast crank and pistons so it's not all beefier on the 5.0.

I would imagine the 5.0 might live at considerably higher boost levels than stock and make quite a lot of power that way. I would stay away from super high revs but I am sure some daring souls will try both to get Big Power.

I do like the cross bolted mains and the oil cooled pistons though, and the block seems to be well designed from a stability perspective. Really it is a pretty nice platform to build out. The engineers did a lot to make it live,even making a great deal more power than they allow in stock form. This is a very modern power plant from a company that focuses its efforts on performance. I think we will see some surprising numbers as more of these get into circulation. It is always a little scary paving new ground.

 

No worries.

No, not at all. The crank is cast. The pistons are forged aluminium vs. the N/A pistons that are cast ally. The rods are powdered

I'm not aware of any engine builder who's had a 5.0L apart and inspected it in detail and put up photo's / detailed reports.

But the 4.0L, 4.2L and the cousin 4.3/4.7L Aston engine has been apart many times. This is an interesting read Vantage V8 4.7 engine rebuild - Page 3 - 6SpeedOnline - Porsche Forum and Luxury Car Resource

To quote Pavel from PRE

"In the case of AM engines I would not trust stock engine components. Engines are built extremely cheap. Cheap to the point where the management probably went to the engineers and said to make components last the length of the warranty and then you are SOL. There is nothing good about stock AM engine components except the crankshaft."

"Jaguar is made even more "economic" than AM. Jaguar uses a cast crankshaft(AM is forged, gun drilled through the mains, and rod pins for weight reduction), Jaguar uses powder steel fracture style rods. AM rods are forged, but look extremely flimsy. I know you cannot judge a part by its looks, but I'm sure if I sent it in to Carrillo for testing it will be inferior to the set they made me for this engine rebuild. These motors in stock form are not intended for heavy duty use. I don't think you see that many engine failures because the cars are not driven hard or they are not driven enough. "

Note that he is talking about the AM Vantage 4.7L and the Jag 4.2L, both of which he re-built. PRE Tuning - Site

What's inside the 5.0L (and 3.0L) remains to be seen, you can probably find info in various technical guides, but it's still very theoretical about how far you can push the 3.0L before something lets go (or perhaps, catches fire?)

 

Somewhere on this site there is a link to an engineering pdf on the 5.0 that goes into great detail on its construction. Something like 50 pages long. It was a pretty impressive read. On the Engines forum there is material from Jaguar quoted indicating the s/c 4.2 has forged pistons and forged rods.

 

Yep, I just double checked it, 5.0L (and one could assume 3.0L), funny they went from forged pistons to cast ones.... ???

Spheroidal graphite (SG) cast iron crankshaft
Forged steel connecting rods are manufactured from 36 Mn VS4 steel...fracture-split...
The cast pistons incorporate a number of features designed to enhance durability, minimize friction, and reduce wear.

 

I believe the pistons are hypereuctectic castings on the 5.0. Supposed to be almost as strong as forged and they don't expand as much allowing tighter bore tolerances. Not sure what kind of cylinder pressures they can withstand. Hopefully much more than basic cast pistons.

Also spheroidal graphite cast crankshaft...who knows how fast it can spin or how much torque it can withstand?

Lots of unanswered questions that should be answered before investing in extra boost and bigger injectors. I assume someone smarter than me will have those answers soon enough. The F-Type in particular is in an enthusiast niche and those buyers will modify their cars. It's not after of "if" but "when" it will happen. I expect to see 700+ hp 5.0 engines within a year or two, probably on stock internals.

As far as how long it will live with higher boost levels, I suspect it will depend on the user more than the power levels.

 

I was reminded of this as I pulled out of a parking lot twice today and had to accelerate hard because a car was coming that I couldn't see until I was well into the road. The rear end breaks free really easy at stock power levels. This may be the one place where AWD will be necessary. I was watching a video of the new Dodge Hellcats earlier today they have a hell of a lot of power but you can't put it down to save your life. I don't even see much point on putting drag radials on these cars because there will always be faster quarter mile machines. You add a lot of power and then you run someone in the twisties you are more likely to have a really expensive lesson because they are already damned lose.


Though when I had the Viper out a few months back and raced a motorcycle on the on-ramp mostly sideways and couldn't hear the engine because my wife was screaming so loudly that was almost worth the price of admission (that and seeing the little speck of a motorcycle in the rear view mirror). Otherwise the Viper pretty much sucks to drive. So I guess I'm still tempted, we'll see.

 

Getting sideways is half the fun!

Your Squeal-O-Meter sounds like mine. I remember the first time she did it - we were jumping waves at about 45 kts in our Formula boat right after we got it. Priceless.