Nigel's 6 litre-mods and results...and plans

well folks i have results long term…as follows:
after changing cams and tuning the fuel delivery and eliminating the italian ignition the results were quite good…for a bit.
with the mods listed above and those i had done previously the end result was 480rwhp. top speed with the factory gearing: 181.35 mph in a measured mile (plenty hairy btw). shift points at 6200 rpm with a fuel cutout at 7k rpm.
there were and are problems though…as follows:
first… the transmission and rear diff did NOT appreciate the addition of the extra ponies in stock form. you use the 4l80e trans you replace the friction innards…no exceptions if you want reliability and make damned sure the u-joints are up to the chore…which the original equipment was not in the long term. again…kinda hairy at speed if not addressed.
second…the stock cam chain tensioner is not really up to the chore long term but we already know that. a fix for that is in the works. it pays to be creative from time to time.
third…the head gaskets. ffs…those damned composite head gaskets. they don’t work worth a damn in the high hp v8’s i have built over the years and the v12 is no exception. the rive gauche blew out to the water jacket…twice. the open deck design allows for a bit of flex and the sealing ring WILL take a proverbial shit and steam clean the unfortunate cylinder post haste! fortunately…no hydrolock.
for this i am designing a cylinder brace to help stabilize them although there are folks that will say that’s not needed. to that i say that if you run your 6 litre as hard and consistently like i do i think it can’t hurt because: block harmonics.
second part of the fix…a copper one piece head gasket ( Copper Nickel Plate & Copper Nickel Sheet | Farmers Copper, LTD. ) cut with waterjet cutter.
all things considered…including the ability to shed heat fixed with a custom built 3 core radiator…not a bad one. the bottom end has held up well. the pistons and cylinders look good. the cooling system as supplied and routed from the factory is questionable. for normal driving it’s adequate. for a performance application here in the states…not so much. that also will be rectified with the engine out freshening.
now…before some folks start up with the proverbial…no…jag got it right the first time…etc i say this:
the entire driveline was designed in england where the conditions are NOT like they are here in the states. the distances we drive tend to be longer per use. we have mountains the likes of which england does not have in general…deserts too.
last but not least…nigel IS the daily driver. as such he’s not parked in the garage most of the year…i run the piss out of him as i don’t really care about fuel mileage as has been the case of all the performance vehicles i have had over the past 50 years.
you don’t buy and daily a v12 and expect 25mpg. i DO have the numbers for that though. 20.5 max and consciously paying attention. not over 60mph.
minimum is 3mpg matted for speed runs.
average is between 12/15 on a ‘normal’ drive.
i use the ecu i designed and built for the fuel injection and trans control. kent cams jag7 spec (hard to come by if you live in the states so i had a set custom welded ground…no small expense)…thank you thomas for the research and execution…skillset way above my own in the land of machinists. he also was the one responsible that made my rear rotors.
so…after all these years of use and abuse i find that the jag has held up well and i have no regrets or bitch sessions about the platform past what i have had to modify (covered here previously) and have spent less time and effort than i have had to building acceptable driving American muscle.
now…if nib and i can get ‘Q’ to fire up the waterjet we’re back in business.
let us know if the copper/nickel gaskets would be something you folks would be interested in.
when the build is resumed (it’s frikkin’ cold here) will post process and results.
be safe. be well and know that the community is appreciated. i have another 20rwhp to find in the naturally aspirated form so i will be busy for a bit.
btw…bug nib. dolly turned out beautifully and he probably won’t want to sand paint for awhile ;-).

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