TWR also had some very clever people and lots of industry contacts too. They invented the first programmable sequential fuel injection system for example, Zytec used that as the basis for the system in the Jaguar Sport cars. TWR couldn't break the 500hp barrier until that came along. But yes, it took several million pounds to get that far.

 

wow...
research into the engine you are using...
Listen to the People that "HAVE" done successful increases using that engine...
I ask... WHAT competition are you planning to compete in... ? and what are the rules?

what are the Base line VE of your engine across the RPM range...
did you know that there are good online tools that compute the NEW compression ratio at any given boost across the rpm range
do you have the VE MAP of any engine....?

I put a lot of work in deriving this table... for my 5.3...

personally… I was told if you are going to generate more than 400 lb/ft of torque that you need to address stress reliving the main caps... first...
in order to make HP you need Torque... or RPMs... and since you do not seem to be a person than could make it turn 9k rpm... you want to go w BOOST... increasing Torque to in crease HP … then numbers... did you run them to see how much torque at whatever RPM you are going to need...? will it exceed the safe limit of 400 lb/ft?
did you figure out and mow many lbs/min of air you will need... in order to select the correct compressor and compressor trim...? have you looked at what compress map fits these number to reach the select torque to generate your target HP...
I would like to just see some sheets and math...

I was waiting to pick up a few neglected ones around here and do the valve unshrouding... some one has kindly shared on this site...
hey that and a nice transmission and I would be a happy camper... I would be shooting for about 400lbs/ft across the range... as torque does get a body moving...

 

Thankfully, the 2871 compressor map nicely fits what I need. And yes fettling the main caps is going to happen.

 

I’ve raced the V12 and unless you’re making a lot more power and holding it that sort of power level for more than 1/2 hour at a time, you’re wasting your time. My experience tells me that the main cause of main bearing wear isn’t the main caps but running out of oil. Modern sticky tires under hard braking or cornering ( or both) cause the oil that once properly warmed up to slide forward under braking or sideways under cornering until the oil pick up is uncovered. There is plenty of room to hold the pan full of hot ( watery thin) oil up in the timing cover case.
That’s why so much time was spent working on baffles and in the end Group 44 went to dry sump). 70’s& 80’s race tires aren’t any stickier than modern low profile high performance street fires especially with TW200.
But go ahead, you’ll have to pull the engine apart anyway because you need to open up the ring end gaps.
Any boosted engine needs the end gaps opened to at least .300 ( from the stock .150 ) the reason is the more power you make the more heat you generate. The first place that heat is felt is at the rings.
Heat metal up it expands. It will expand until the tips contact each other. Once it can go no further the rings will start to curl, popping the top off the piston land. A piece of aluminum can do a lot of damage floating around in the cylinder. And even more traveling through a turbocharger.

So you’re going to do a heads off rebuild if you want to turbo your engine.

Gaps that big will cause a lot of oil consumption and smoking. Some will try perfect circle rings and stagger the end gaps but real thin rings tend to react poorly to turbochargers. You might call perfect circle and get their opinion.

All you need from a Pre HE is the heads and pistons.
that’s junkyard stuff and I scrapped over 30 of those in the late 1990’s I still see them go through the auto auctions and on Craigslist usually not running but you don’t care. Just go to the web site that sells car-parts find a junkyard near you and grab an engine. $300? While you’re at it grab the early distributor. It’s easier to put a great curve on that one than the later distributor.
If you’re wondering, yes the early pistons, distributor, and early head will fit right on your block like it was made for it.

There is a1973 V12 sedan that’s been in a fire you can have for scrap metal prices. In Kansas at the auction. Heck any rusty old wreck prior to 1981 will have what you need. Two web sites to hunt through.

 

MG WTF , .300 ring gap?

 

my XJS is a 1992... old stately top down convertible... I enjoy... driving it around with the wife... I get oh.. you want to race late on Fridays... by wantabees... I just smile and say No...
I raced before I got married... my last season was good... 10 events 9 1st places 1 second place... SCCA regional solo II but job, kids, wife... like I said
RULES! read and follow the rules... even a bad driver can win if he just follows the rules...<GRIN> (my brother came in second for the season... last in a lot of events.... but still second in year end points...)
God Love him... it was his car, and he thought I spent too much time studying for my Math and engineering classes... so he got me going to events with him... the year before and I told him we could win by following the rules and we did... long time ago... it was fun... many more fun times since doing other things...

best to all, BE WELL!

 

yeah. what heat and rpm range would you need 300 thou...

"The top ring gap will change based on the amount of heat introduced into the engine. Most folks say the gaps on the second ring are driven more by the cylinder bore diameter. ... As a basic rule of thumb, a gap of 0.004-inch of end gap per inch of cylinder bore diameter is a good place to start. "
I know from my crazy high rpm spite engine that I had to gap them pretty wide... because as the heat made them expand I did not want them to close the gap and then BREAK... with 9k rpm
but not that big...

 

stock end gap is .150 from memory. Could be wrong. Basic end gap rule is you increase the end gap according to power increase. 20% increase in power go for 20% greater end gap double the power , you double the end gap. 600 hp is slightly more than double.

 

I’m seriously impressed. To haul that big, wide, heavy car around an Autocross track and win that often!!! Well done.
I’m a wheel to wheel racer. I like to dive into a corner stealing the line away from a faster car and block him enough so I can slow mine enough to get around him.

That’s real racing to me. Judging things that quickly on the absolute edge of traction without endangering him or me.
A faster car will win unless he can be out driven. That’s when I come alive. That justifies all the work.

As for racing on the street? I don’t have the stones for that. Too many innocent people at risk.
That’s also why I think a lot of guys driving a Jaguar are just poseurs. It’s a 150 mph car that is bog slow acceleration due to all the luxury stuff and is just a snore to drive. But convert it to racing and it’s an absolute blast.

Since you can turn one into a serious race car for a tiny fraction of what even a street restoration costs it makes the most sense. $5-6000 to buy the car and will get you on the grid in a safe car with reasonable expectations of finishing. That is value.

 

Here's why turbo / super charging the V12 wont net the power some think. Dreamers... stop reading now, you're about to be crushed. Just 22 degrees ignition timing on a "Jaguar Sport Engine"? The General rule of thumb for forced induction on pump gas is 1 degree of ignition retard per lb of boost. So a V12 at 10 PSI would be running just 12 degrees of ignition advance. That's not ideal and would lead to very high EGT going through that long exhaust runner and a serious reduction in power. Think of it this way...if you run just 12 degrees of ignition advance on the NA engine it would make about 200 HP... add in 10 PSI and you might get to 320HP and make lots of heat. Hardly worth the effort. 110 race gas or E85 might allow for 0.5 degrees/ per lb so that would be 17 degrees of timing. Still not great, once you get below 20 degree of advance on any engine NA or otherwise power starts to diminish greatly. Of couse someone with mega bucks could cast a custom set of heads and CNC machine a modern combustion chamber design, with modern pistons, rods, dry sump etc but I dont think that will ever happen.

So this brings you to the next logical conclusion, AJ16 heads on a V12 with turbos. The AJ16 head is far more advanced, has a shorter exhaust runner and pre-ignition resistant chamber design. 600 HP with a few PSI from Turbo's would be a starting point with this configuration and that would be too much for a street XJS, something like this belongs in a X13. It's not so far fetched. There are more AJ16 headed Jag V12's running around than turbo'd ones. Far more practical is a Turbo AJ16. With it's 220 HP in NA trim it could go to 400 with best practices like a good tune and charge cooling. The HP wouldn't be the story though, it would be the stump pulling torque that both the AJ16 and Turbo'd engine are famous for.

I maintain if all out performance is what you want... then the chevy LT1 swap is ideal for the budget minded. LS for those with deeper pockets.

If you want the V12 experince, leave it NA, swap in a manual transmission and run straight pipes, no cats, only rear resonators. No other GT drives or sounds like it... unless it also has wings or a prancing horse on the hood. You wont be winning any drag races, but it could do OK on a road course. The real story is the sound, the driveability, the reliability (later 6.0), the experience and miles of smiles from a more organic and connected XJS that could actually get done.

 

We call these people BMW drivers these days becasue you can find this aberrant track behavior often displayed by BMW drivers. It's a phenomenon. In the pits you might hear faster drivers talking about a **** blocking slower driver described as "that BMW using the whole track" even if they're not driving a BMW.

 

It’s called racing, not being polite. Or good road manners. The fundamental rules for safety are the over taking driver is responsible for executing a safe pass.
Not a safe pass that doesn’t offend the other driver. Or pass only on the straight.

Once you are ahead of the passed driver ( and it doesn’t matter by how much) the person being passed has to ensure a safe repass.

Smart, aware, drivers having that pass done to them will tuck underneath the passing driver and use his better positioning to accelerate away as the inside pass guy goes wide.

Any pass attempt has a safe, proper way to deal with it. Blocking is wrong and simply not allowed. Although I see plenty of mirror drivers move over to block. That’s just bad driving.

Racing is 3 D Chess at high speed.

In all the decades I’ve been racing ive learned that unless I know the driver I’m passing I’ll give that driver plenty of room. If he does something stupid I don’t want to mixed up in his stupidity.
But it’s fun to race, really dice right on the absolute edge of control with a trusted racer.

I watched Sir Stirling Moss dice with myself and Steve Kline in the Bahama’s
Kline got a jump at the start and moved over ahead of Moss into turn one. I was right behind Kiline and moved up next to Moss block Moss from doing the tuck under pass.. Moss and I were even going into turn 2 but his Aston Martin DBR2 had more power than my Jaguar. And out of turn 2 he pulled me so we went into turn 3/4 with me trailing but inside Moss where I did the late braking, take away the line out of 4 But Moss saw that coming a mile away and Re passed me on the inside. That’s how we finished Kline,Moss, myself. I have a picture of both Moss and myself smiling laughing with our arms around each other’s shoulders. He loved it.
The final race of Speedweeks 1986 It was Moss who got the jump. And He won that race with me second.
That’s also how we finished the week Moss First with me Second and Kline 3rd

Just for the record? In 5 decades of racing ( a few at very high level) I had one minor accident on a cool off lap when the throttle stick wide open on entering a corner. It took me less than 20 minutes to totally repair the damage.

 

icsa , you know you make valid statement about BMW drivers, me and my wife notice even on the road they are arrogant, and aggressive !
more so than other type drivers!

 

!

E gad MG that was like a hundred yrs ago, or seems like it !
things have changed and people have changed also!

 

First to the checker still wins.
Passer is still responsible for a safe pass.
Rules are pretty much the same. Sounds like the previous poster was talking about track day rules. For those he’s right. I don’t do track days. It’s not racing, just guys playing with their cars.
I realize fewer and fewer people are doing wheel to wheel racing. Vintage, LeMons and Champ Car are about it anymore. SCCA doesn’t want old cars or cheap cars anymore.

My last race I drove at 2017 My license was still valid. Today I’d need either a waver or a regional event. Depends who’s comp chief.
Paul Newman was running LeMans in his 80’s Stirling Moss too was racing into his 80’s
I’ve got a few years left.

 

I have to agree about BMW drivers. But my prime objection is Honda Odyssey drivers. Nothing against most Honda drivers. My wife drives one. But Odyssey drivers seem befuddled and slow.

 

I’m in complete agreement with everything you say. One exception. Stop thinking about Chevy swap into a Jaguar.
Want more power? Pick up a XKR engine with 510 horsepower. Instead of lumping it’s called an upgrade.
Nothing wrong with Chevy. I’ve owned them most of my life. But it doesn’t belong in a Jaguar. If you want to swap Chevy motors into something, Swap it into a Cadillac. That’s what GM did.

 

@icsamerica One thing about e85, if I ran it with a massive turbo to supply 1000hp and went for it, it would make that much power for a second. With any e85 and boost it's best to start at 20° and go up. Also, jags run such little total timing due to no knock sensor to run it on the edge. With a knock sensor and intelligent management, this story would be no different from any other engine, if not worse could be slightly better due to the efficiency of the chamber. I could be wrong, but I have a feeling not much tuning experience with modern electronics is going around this forum. I almost might completely stop working on my dodge to get this project done as soon as possible. But if a ran e85, and if the motor took it, I would absolutely be able to make 1000hp, probably only a few seconds though.

 

Also, dos anyone have any pictures of v12's destroyed from boost? I do have a picture of a broken main cap. In 6 months maybe I'll have a picture of the street with parts all over the place.

 

Alcohol will always cool. Same as a intercooler will. But silly numbers like 1000 horsepower require more than production pieces.
As far as timing goes. Are you talking about static or total advance?
early pre HE engines ran with 10 initial and up to 40 degrees at 3000 rpm.