Build Log SCF/RCR Jaguar XJ13

In it's most highly tuned form (Miura SV) the 4 liter engine was claimed to make 380 at 7,800. Many people scoff at those as being "italian" horsepower, however, including, I believe, Bob Wallace himself. Safe redline was no more than 8,000, I believe, and that was accomplished with very stiff valve springs. So I don't think you're going to get XJ-13-type horsepower that way, although I will defer to Chad on that. He definitely knows his Lamborghinis.
You may be correct as I am no Lambo expert. I guess a safe redline depends on how brave,rich, or stupid one is. I read some where that Bizzarini claimed with some upgrade you could turn 11k rpm Yikes. I would be more inclined to believe the 8k number especially for a stock motor which is still not to shabby.
The lambo motor is out of the budget right now but fun to think about. I believe my current engine will give me more than I need for this car. I think if one were to stick a nice stock 5.3 V12 engine in this car it would scare the daylights out of almost any other road car.
 

Alan Watkins

Lifetime Supporter
I read some where that Bizzarini claimed with some upgrade you could turn 11k rpm Yikes. .
The version of that I recall was that when Bizzarini built the prototype engine for Lamborghini he was under a bonus scheme tied to how much power he could produce. So he tuned it as a racing engine and got a much larger bonus than anyone expected. Lamborghini had no interest in racing so when it came time to put it into the street car it was destined for it was detuned to a little over 300 hp and a redline of 6500 as a 3.5 liter. Anyway don't want to divert your build thread further.
 
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The version of that I recall was that when Bizzarini built the prototype engine for Lamborghini he was under a bonus scheme tied to how much power he could produce. .
I love it when people exploit agreements in their favor... here Lambo didn't want to race but didn't contemplate that Bizzarini would build a racing motor. Fantastic!
 
A somewhat true story, Bizzarrini had the design in his pocket because he had designed it for the new company called ATS that was formed by ex Ferrari employees. The V12 engine was to be used in F1 and a Stradale, however like many of Bizzarrini's dealings it ended in a argument and Bizzarrini left ATS. He then heard of the tractor manufacturers intention to build a GT so he sold the design to Lamborghini.

Bizzarrini read the contract carefully like all racers read rules and found the HP clause, it is also understood that he played with the dyno a bit when it came time to test his masterpiece. Bizzarrini and Lamborghini ended up in court and the ruling on payment was in Bizzarrini's favor.

Odd as it may sound Bizzarrini's favorite engine was the 327 Corvette, he claimed it to be the best built engine in the world, this is quite the compliment as Bizzarrini was "THE" builder of the Ferrari GTO and Lamborghini V12. Bizzarrini designed a Magnesium oil pan and a cross ram intake manifold for the 327, this design was later pilfered by Zora Duntov for the Grand Sport Corvette.

Another interesting fact is that Bizzarrini was well schooled in aerodynamics while working at Alfa Romeo, he used this knowledge to built the Ferrari GTO and then while working on Iso Rivolta's A3C he incorporated the Kamm tail into the design. This was two years ahead of the Cobra Daytona! You hear all these stories of how revolutionary the Cobra Daytona design was yet the A3C and later the Bizzarrini 5300 both had Kamm tail designs built in and years ahead of the Daytona.
 

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I am finally back on the project. The last couple of years have been filled with distractions. I though I was moving forward in late 2013, then came 2014. An amazing series of disastrous events for me and my family made it the worst year in my lifetime. Even with all the sadness and problems there is always so much to be thankful for and 2015 is going to be much better, I am certain of it!
I have had an unusual health issue and also come to the realization that I cannot accomplish as many things by my self so I have enlisted some help. We are sorting out the car and look for progress to be reported here very soon.
 

Randy V

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Glad to see your return to this project!
Sorry to hear of the health issues...

Any news on the engine front?
I have to say that I was a bit concerned about the 13:1 compression ratio of the original engine you were working with. I don't know about your area, but the racing fuel required to manage that high of a compression is not only hard to come by, but expensive. An alternative that a lot of people are going to is the E85 ethanol fuel. This works, but requires modifications to carburetion/injection and brings about a host of contaminated fuel corrosion issues - particularly around alloy..
 
Yes we will be running 13:1 CR. The Jaguar V12 used two different head designs. The earlier one called the Flat Head or Pre-HE used a bowel shaped piston for the combustion chamber. The Pre HE design allows the use of larger valves so it is often considered the only one to use to really stretch the engine. With this type head you can make huge HP (600-700) BUT it is susceptible to detonation so big HP means racing fuel. The Pre HE in US spec was 7.8:1 CR. They did build engines up to 10:1 for some other markets but that was as high as they would go with pre-HE for production.
The later fireball head which we are using was designed by Michael May and appeared from 1981 until the end of production. It is referred to as the HE (high efficiency). This designs uses recessed valves with the plug in a pocket near the exhaust valve for the combustion chamber. It allowed much higher CR, could run much leaner and therefore improved mpg by something like 20%ish. Unfortunately this designs greatly limits the size of the valves therefore generally limits HP to about 400 HP. With lots of extra port work and some heroics the HE can produce more but it is doubtful that one could exceed 500 HP. The stock HE engines were 11.5:1 CR with some running 12:1 that is for a production engine in a road car to run on premium fuel. Jaguar experimented with up to 14:1 with this head with good results but dialed it back for production so I think the 13:1 will work out. I am planning to build/tune the engine to run E85 but I would like to have several states of tune one being for 93 pump fuel and maybe another one to de-tune enough to allow someone else to drive the car. My engine has had a lot of port work and will be using fuel injection through 12 individual TBs so I am hoping to see about 450 HP with E85 maybe 475 if we are very lucky and 425 on 93 pump. Since I have two tanks I can have one for E85 and one for 93 then I can switch between them.
 

Randy V

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Admittedly, I don't have a lot of in-depth Jag knowledge although I worked a fair amount on the old 3.8's and some with the 4.2's.. Unless your cams will have extremely close lobe centers, I don't see how you will get the 13:1 engine to run on 93 without detonating.. There are ways with variable valve timing and direct injection along with extremely sophisticated ignition systems that it would work.
 
Admittedly, I don't have a lot of in-depth Jag knowledge although I worked a fair amount on the old 3.8's and some with the 4.2's.. Unless your cams will have extremely close lobe centers, I don't see how you will get the 13:1 engine to run on 93 without detonating.. There are ways with variable valve timing and direct injection along with extremely sophisticated ignition systems that it would work.

I have a 1994 XJS coupe with a stock 6.0 HE engine with 11.5:1 CR and it runs superbly on pump gas. Of course it was built to run on available fuel as it is factory un-modified. I usually use 93 premium which is recommended in the manual but I am sure it would not have an issue on 87 on occasion. I know 13:1 is higher and I expect it to require some timing setback for 93 octane but with E85 we should be able to extract something more. I guess we will find out later this year.
 
We will be adding mufflers at the end of the line to make for an acceptable street car. I have been told by another builder that without mufflers it is VERY loud and the police will be on me immediately. We can's have that for just puttering around. Of course that should be expected when I am being a bit silly.
 
Hi Chuck
Progress is the key now. The project has been delayed way to long but I am determined. I am hoping it will move at a reasonable pace now. I will be posting updates routinely. This thing has become way more complex than I had ever envisioned but I expect that much more rewarding in the end.
 

Chuck

Supporter
Hi Chuck
Progress is the key now. The project has been delayed way to long but I am determined. I am hoping it will move at a reasonable pace now. I will be posting updates routinely. This thing has become way more complex than I had ever envisioned but I expect that much more rewarding in the end.
No doubt the XJ13 is a complex kit.

Saw two under construction at RCR today. One had a nice British racing green paint finish. Beautiful car. The final result should make it worth it.
 
We have a bit more done to the car now. Installing the fuel tanks took some ingenuity. We cut out the rear section of the sill area and made a hatch that could be mounted back in place after the tanks are in. The tanks are held in place with a rubber covered threaded strap front and rear. They can be tightened firmly from the outside and there is no movement.
Since these are side mounted tanks I am not thrilled with the idea of large amounts of fuel coming out of the filler tubes on blast off. I know we can put baffle material in the filler tube which we will do but I feel safer with baffles in the tanks. We are going to put three baffles in each tank anchored 1 inch off the bottom. After the baffles are installed we will pressure test the tanks before the final installation.
 

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Thanks Ryan looks like they have some really cool things happening. Would be nice to have folks like that a little closer to me.
 
Another resource could be Donovan Motorcar Service located in Lenox MA. Not only does he restore and service Jaguars but he has an active racing program. No affiliation but I have visited his showroom many times.
 
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