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I too just want an friendly give and take on the debate of JaguarV12 versus Chevy.
I’m not anti Chevy. Over my lifetime I’ve bought 11 new Chevy’s and 3 used. They are a good value.
I’ve only bought 7 Jaguars all used- really used. $300 Each used ( except my most recent which I paid $500 for. ) They were all bought to be race cars. That doesn’t mean I’ve only owned 7. I’ve lost track of the number of Jaguars I’ve owned.
As I said for decades I built racing engines and I’m at least as comfortable with Chevy small blocks as Jaguar V12’s plus MG T series. Jaguar cast iron six Plus a couple of oddball engines like Climax and Buick.
Racing engines don’t get the rest a street engine does. You’re using that engine to the limit for 30 minutes to several hours at a time. What you can get away with on a dyno and street drag won’t last when peak demand is called for a whole race long.
So I’m conservative. I race on a tiny budget that building and maintaining others Race cars provided me. ( I had a normal day job for family income) Racing is about results. Customers come to me because Of the results I produced.
I know a seriously competitive small block cost $11,000 in parts and machine work back in the 1990’s. Because I’d build at least one or two engines a year for various people. And I was cheap! NASCAR small blocks cost $40,000 in parts and lasted 2 races.
Yes you can make some horsepower for less but you risk durability. And you don’t need the most horsepower to win. You need to finish.
Ronbro is the only one I know who has seriously gotten the fuel injection working. compared to him I’m a Luddite. Playing around with carburetors when I know ultimately there is more power with Fuel injection.
When I built my Chumpcar V12 with twin turbo chargers I know I left a lot of power and used a lot more fuel but it worked, even if it was badly Kludged. Only the first years can be modified like that. If I were to repeat a turbocharged build I’d have to go with Fuel injection.
Sticking a Chevy engine where a Jaguar originally lived isn’t cheap. Because of demand good used Chevy’s command a premium over the price of good used Jaguars. now add the cost of the swap plus upgrading it and a transmission because a Chevy won’t fit on a Jaguar transmission.
then the weight.
A Camaro can be much lighter than a Jaguar. Since they are basically the same sort of car.
If you haven't biult a sbc sense the 90's it makes a lot more sense now days the sbc aftermarket is flooded and everything is dirt cheap. Most people are going ls now. When talking about a "hot rod" I think a street car that might see a few test and tune nights at the drag strip not a circle track car that's going to turn 7k rpm for 30 mins straight.
I'd love to see some pics of your chumpcar. Sounds like a fun biuld. I did 24 hours of lemons once but we used a 01 v6 automatic camero put a supercharged 3800 in it. The car was pretty awful as I biult in about 3 weeks including the cage and everything else. But it did last till the last hour of the second day when it started rod knocking bad. Came in and I tried to run one last lap to cross the checkered flag but it said no more about half way around the course...lol
I’m a road racer. Not circle track. Although to be honest I started out with that.
Most of the guys I built for were Vintage racers and that’s what I did.
The last motor I built was the winter of 2001 and yes I saw a lot of change from the previous 30 + years.
When I started we’d hear about a new cam profile or whatever put it in an engine and see what the results were. Sometime in the 80’s I started to design modifications on the computer based on flow numbers and other measured input. Then test on a dyno.
As I started to find consistent data with results I did more and more on the computer and less and less testing and back to back comparisons.
The Chumpcar never went to the race track. I had just sorted out the tuning issues and was ready to install the rollcage, etc When Chump car came here to Brainerd for an event.
I had carefully read the rules about documenting the $500 limit and was under that. But when I asked questions and they heard I wanted to bring a near 500 horsepower V12 they told me about penalty laps and car crushing. Clearly making me fear bringing it.
One of the guys who’d helped me, offered to buy my share of the car as it sat and make me finically whole.
He shows up every once in a while At a local event doing smoky burn outs. It’s a $500 car and not pretty. You don’t see the turbo’s because they are under the front fenders out of the engine compartment.
Don't know about chump car as iv never run in that series but lemons wouldn't have given you a hard time about it. Jaguars have a horrible reliability recorded in lemons slap a home brewed turbo setup on it they would never expect it to finish and they like unsusal cars. No one takes it to seriously unless you show up in a BMW with super cheaty suspension or something like that bribe The judge with some ***** shaped Candy's and your good to go...lol
Today I’d be welcome with open arms in Chumpcar ( now Champcar). But in the early days they were much more defensive.
Reliability in racing is about preparation. So far the V12’s that have been running are the HE versions with 11.5-1 compression ratio. The fuel charge with those is super lean and if there is a dirty injector or two the charge gets super lean and stratifies. The result is blown head gaskets. The solution is to go to bigger injectors or use the earlier pre HE head ( called the Flathead)
In that case Fuel mileage is decreased which is a kiss of death since 5 minute fuel stops are mandated. Compared to more fuel efficient cars like a BMW or Honda you wind up stopping almost twice as many times.
In addition with so many complete novices who often fail to use their mirrors passing becomes a very scary proposition.
Hi, this is Andrew from Jaguar Specialties and I just wanted to add some technical comments here, not to convince any one to do anything, but just to make sure the right info is out there.
XJS conversions are pretty hot now, and from where we are, virtually all of them are LS. Not to deride the LT1- it's a great motor and I had one in my own 88 XJSC for 15+ years, and loved it. But it's hard to deny the breadth of LS offerings- there are just so many choices in displacements and outputs, transmissions (5 different 4-speed autos, a 6-speed automatic, and of course the the 6 speed manuals, all that came in factory GM cars/trucks- supply is no problem. These are a great option for a Jag.
And I also wanted to clarify some of the perhaps murky/misunderstood details about conversions into these cars in general- everything in the car will work as well as original, if not better:
1) Gauges- all of the stock gauges will read properly with the LS (and that does not require making ANY modifications to the cluster, nor even removing it from the car).
2) Shifter- the Jag shifter is after all designed to work with a GM trans, so it has no problem (when using the right parts) working with any of the automatics.
3) AC- actually, in this area, the conversions do even better as they use a more modern parallel flow AC condenser which is wildly more efficient that the Jag original. As a result, R134a will work here. Also, no special (or any) changes are required the remainder of the AC system on the Jag chassis- all stays stock,,,,
4) Wiring- for anyone able to read a wiring diagram, integrating the GM fuel injection on the Jag is simple- the car was injected to begin with so you're halfway there....It all all works well. You either need to do the research yourself or work with a supplier who knows the process....
5) Would it surprise you to know that nearly 95% of the parts needed to do this are off-the-shelf, GM type replacement parts???? The radiator, molded radiator hoses, fans/shroud, AC condenser, exhaust manifolds, and many other pieces come right out of the GM parts bin. That makes these builds easy, inexpensive, reliable, and easy to maintain....(you'll fall off your chair to find the radiator, brand new, is only around $100.... with a lifetime warranty from many different suppliers)
At the end of the day, you get in, turn the key, and the car starts and operates just as it originally. Driving is a dream. And that can be the result every end user can get, assuming the car is built with the right parts.
While the output of most basic LS engines (LS1, 5.3, etc.,.) is modest (300hp range), don't forget that the aluminum LS engines are 400lbs lighter than the V12 (based on my own car, on the scales). That makes a huge difference in performance, not to mention handling. And the chassis itself, with mild upgrades like better shocks, good bushings, etc.,. can easily handle 425-450 hp, and we have many customers running that level, in both street and even an autocross or 2. The car handles it all well. Beyond that level I think it would start to get squirrelly, but we have all seen (claimed) 700 hp v12's in the Lister cars and others, so it has been done, successfully.
And to give you an idea of what's going on out there, see below some pics of a 90 XJS convert going together a local shop here in California. (Panavia LLC in Campbell, Ca). This car will need to be California legal (emissions) so it is using a special GM LS3 Erod package, that develops 430 hp, but is also California legal for any 1995 and earlier passenger car. While I'm not sure I would have put 430hp into one of these early XJS converts, the emissions part of it is what drove that decision. With a matching heavy duty 4L65E (4 speed auto) trans, the car is quite a drive. And this package like more of the GM crate engines, comes with a 2 year warranty.....
For anyone else, something in the 375-400hp range, with perhaps a more aggressive differential, would be plenty.....
A conversion like this, done by a professional shop, in total, would come in at just around $20k. Do your own labor and trim off 30-40%..... Use a more modest engine package (like an LS1 or LS2, or even a truck based 5.3 or 6.0) and the cost could drop 60% or more.....
Everyone should do what they like but now we all have good info.....
Again I wanted to provide these details purely for technical content and I hope they're helpful.
for the cost and technology and modifcations, the LS and new LT series is the the BEST in the world !! lot of suspension mods, custom wheels etc!
done in 2010, 4L80 trans, 3.42 rear gears!
ls engines are leaps and bounds better than the old sbc's when i blow up the engine that is in my jag now ill probably seriously consider going to a turbo ls setup.
a lot of my build was dictated by what i could build using up stash of stuff i already had. if i had been doing it from not having anything i would probably look for a complete wrecked car/truck with a 5.3-6.0 ls
400 hp is a really nice power level for the jag im sure 99% of people would be extremely happy with there jag at that power level. i drove my car for about a year or two at that power level it was a little soggy down low as i built the engine for boost so the lower c/r killed some power down low had to crutch it a bit with a lot of initial ignition advance. but it was still really fun to drive good balance of drive-ability power. now with 7.5 psi of boost on e85 on stock tires full throttle is almost completely unusable as it would break the back end loose punching the throttle even when already doing 60mph on the highway. going to a modern 18" summer performance tire though would keep it hooked up over 45mph or so and now going to a even wider semi slick rear time it will stay hooked up over about 35. my car is without a doubt overpowered but that is kinda what i was going for.
Mguar are you saying each of the 4 exhaust manifolds weigh 4Lbs for a total of 16lbs? How much weight does a reduction starter save? Thanks.
Originally Posted by Mguar
Weight wise You start out with a V12 that weighs 730 with 16 pounds of cast iron exhaust manifolds. That is minus A/C alternator air pump and power steering pump. But with starter. You can lose some weight by going to a gear reduction starter.
.
Yes 4 pounds each. I don’t have any gear reduction starters sitting around but they were light one handlers. While the regular starter I always carried with two hands.
The later 6.0 has the gear reduction starter plus there have been various suppliers in the past so I suspect there are a variety of weights.
ls engines are leaps and bounds better than the old sbc's when i blow up the engine that is in my jag now ill probably seriously consider going to a turbo ls setup.
a lot of my build was dictated by what i could build using up stash of stuff i already had. if i had been doing it from not having anything i would probably look for a complete wrecked car/truck with a 5.3-6.0 ls
400 hp is a really nice power level for the jag im sure 99% of people would be extremely happy with there jag at that power level. i drove my car for about a year or two at that power level it was a little soggy down low as i built the engine for boost so the lower c/r killed some power down low had to crutch it a bit with a lot of initial ignition advance. but it was still really fun to drive good balance of drive-ability power. now with 7.5 psi of boost on e85 on stock tires full throttle is almost completely unusable as it would break the back end loose punching the throttle even when already doing 60mph on the highway. going to a modern 18" summer performance tire though would keep it hooked up over 45mph or so and now going to a even wider semi slick rear time it will stay hooked up over about 35. my car is without a doubt overpowered but that is kinda what i was going for.
I built a junkyard XJS with a pair of used Saab T2 turbo’s out of the engine compartment under the front fenders. Using the early Bosch system and a cheap EFM the print out said 486 hp.
It was a really kludged system. Probably a lot of power left if someone would dial in the fuel And timing properly.
The trick is the Early flatheads 1971-1980 flow magnificently. They have made over 750 horsepower. Whereas the HE was designed to meet California’s new emissions laws. They limit power output to about 450 and getting even that far is very expensive.
ls engines are leaps and bounds better than the old sbc's when i blow up the engine that is in my jag now ill probably seriously consider going to a turbo ls setup.
a lot of my build was dictated by what i could build using up stash of stuff i already had. if i had been doing it from not having anything i would probably look for a complete wrecked car/truck with a 5.3-6.0 ls
400 hp is a really nice power level for the jag im sure 99% of people would be extremely happy with there jag at that power level. i drove my car for about a year or two at that power level it was a little soggy down low as i built the engine for boost so the lower c/r killed some power down low had to crutch it a bit with a lot of initial ignition advance. but it was still really fun to drive good balance of drive-ability power. now with 7.5 psi of boost on e85 on stock tires full throttle is almost completely unusable as it would break the back end loose punching the throttle even when already doing 60mph on the highway. going to a modern 18" summer performance tire though would keep it hooked up over 45mph or so and now going to a even wider semi slick rear time it will stay hooked up over about 35. my car is without a doubt overpowered but that is kinda what i was going for.
As long as you maintain that V12 it will out last you and your son.
I don’t deny that newer engines will make more power than an engine Conceived in 1954, designed in the 1960’s and built on WW2 era machinery.
Spending $20,000 to put a newer engine in though doesn’t seem like a smart choice.
[QUOTE=ronbros;2265674]for the cost and technology and modifcations, the LS and new LT series is the the BEST in the world !! lot of suspension mods, custom wheels etc!
done in 2010, 4L80 trans, 3.42 rear gears
