Just a few words on bore sizes:-
90 std works fine, no known problems
91 bores std works fine, no known problems (std + permitted oversize for racing)
92 works well used in a couple of XJS race units and in Group C and GTP with 75 or 78 cranks. Special gaskets Group A , coopers rings Group C and GTP.
93 / 93.5 possible and used by Ron Betty on occasions, too thin and prone to crack if std liners used.
94 Group C , block needs boring and std style slip fit coopers rings used. Block boring required.
95 GTP coopers rings used with ring exposed to the bore which makes me twitch but no problems reported. Block boring required.
96 Rob Beere, early press fit custom liners crack around at the bedding seat, pain in the butt as total strip necessary to rectify. Later 96 with 'off the shelf' liners + std slip in fit work much better, Special gasket needed but works well. Block boring required.
98 / 100 needs offset block boring and you are on your own for liners and gaskets.
Armed with this info go for 90 92 or 96 all the rest will cost you even more money and may haunt you in nightmares.

 

Interesting that your experience draws a line at about 92 mm for boring the OEM sleeves.


Does anyone know, will the XJ6 92mm piston work in this engine? Pin height workable, wristpin details the same?


What do people use if they go 92 mm?


-M

 

bob tilley in texas has a set of 94mm sleves that he has from a car that was 7.0 with an 84mm crank.

 

once you go past experince and use , nothing,, just can blow up,thats all!

building engines that go beyond recommended levels,really relates to available money!

mike i doubt xj6 pistons would work, if they did we would have known already about it

what to use for any bore piston? (except stock) should be a custom designed piece.

 

question; does anyone on this site have an actual running 6.5-7L jag V12,(except 5006)??

anyone??

 

There were 2 styles of liners at 94, the TWR ones are for coopers rings instead of head gaskets, the 'normal' ones were from Lister who acquired used TWR pistons and put them in their units. Check your wallets first before you go the coopers ring route. Not easy to find either.

The question should really be why go 94 when 96 is easier and cheaper, not to mention the disproportionate increase in power it gives.

 

I went with 96mm and a 74.5 stroke. because the stroke could be easily made from the stock crank without welding

 

Group 44 went 75 and 92 or later 95 for 6L and 6.5L , buzzy nice engines.
The problem with the 96 pistons with the shorter stroke is usually the extra weight. This is only a problem in high revving race engines. All these super dooper piston makers usually only have a few std piston forgings which they machine up dependent of whats needed. The Beere pistons (cosworth) at 96 were machined on the top for different strokes and comp ratios, the shorter stokes ie under 84, had extra meat on the top to give the extra comp ratio. Thats 4.75mm more on a 74.5 compared to and 84, thats a reasonable amount of weight. Reciprocating weight at that. But most aren't going to want 8K before changing gear!

 

the pistons I used were engineered from.the drawings rob beere used and matched to the weight of the original piston. they charged me a decent fee to do that but it seemed like a good idea

 

Soo what would be the best reliable combination (Jaguar and reliable in one sentence?!?) For me its all on reliablility it is essential . Soo what would be the best combination? Thicker liners a small bump in bore size and magneiseum pistons? Billet Aluminum rods? Stock bore and stroke is 91.5mm and 75mm?

 

Just in case it is of interest to anyone, on UK Ebay there are a number of unmachined blank 84mm forged crankshafts for sale, originally made for TWR:

Jaguar -TWR / Jaguar Sport V12 84mm Blank crank forging | eBay

Greg

 

greg they been on ebay for more than 2-3yrs, the JF site went over the cost of machining ,lightening, shaping counter weights, drilling oil passages, shot peening , and nitriding the bearing journals for hardness,and finally balancing!

cost more than a shaft all done and finished!

just looked at pix of it, it isnt even drilled for flywheel or harmonic balancer, no rear seal surface, no nothing, cost would be outragous.

and the shop guy would have to WELL experienced!

 

88 you gotta get a Jag V12 engine manual, stock bore is 90MM, and stroke is 70mm, for 5,3sL engines.

6L is 90+74.5MM stroke changes involved crank and pistons, rods the same!

best way for cost effectivness,,is get a factory 6.0L engine and mod it for a set of turbos, and tune it carefully!

 

88 i know you are just kidding , magniesium PISTONS??, they would catch fire and melt from heat, magni..when lite on fire burns and cannot easily be put out.

but recently some super race engines are using steel pistons( interesting technology)!

 

ron, 6l is 78 x 90.
74.5 is the stroke I stroked mine too.

but ron, if you get a 6l, you're going to need to drop compression to use turbos. so there is custom pistons, and rings. then you'll need.two good turbos, and working at a shop that builds 1000+ hp evos on the reg, a good turbo will cost you atleast 1600 a piece, times two, and then there is the fabrication of the turbo manifolds, which is gonna take some time(money) and then the intercooler setup which will restrict the airflow to the radiator, and intercoolers are not cheap.
THEN you need engine management, (which.I just purchased) and that won't be cheap, the electromotive tec3 6/12 I bought was around 3000$ new.

 

and magnesium pistons.are becoming a big thing in racing. they are alloyed to make them stable, and they make the engines.rotating mass much lighter

 

Thank you calvin , I haved used magnesium pistons for a bit over 4 years now on various projects never hsd an issue .we use them on racing mowers they take the abuse just fine with extreme heat and a slosh system so they're sometimes oil starved .we had one guy run a complete race at the end of the season with zero oil in the engine he came in second. Never knew until it was taken apart in the trailer what had occured. But I do agree I need a shop manual!!

 

I inquired a while ago about those and the shipping was going to double the price. So for $!000 for a blank and another $1000 to have it machined and finished I could get a billet made for about the same price.

BTW the Jaguar factory 6.0L crank is 78.5mm, this can be stroked to 83mm without welding

 

slight off topic; google 1320video, go to texas streets!

500hp cars are not even pictured, but a couple of fast as#sed EVOS are. turbos are bigger than the engines?

these texas guys,houston area, say they have the fastest STREET cars in the world, a friend of mine says i know some of them! YIKES. last time one of them gave me a ride,scared the living crap out of me, 130mph on a local street austin tx.

shows what unlimited money can do!

just something to show that ALL fast cars are forced induction. 200++mph cars are common.

check it out!

and Hennessy motorsports are just down the road! imagine that!!!!

 

hey ron, what do a 300hp twin turbo supra a 500 hp supra and a 800hp supra have in common?