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Where do you intend to race this 600 horsepower V12? Why not spend the money it would cost you and buy a XKR?
Are you willing to accept the depreciation you will get when you modify it? Hopping up an engine scares 99.9% of buyers away except the one guy who wants exactly what you have. With no other buyers coming forward you will have to market the heck out of it. And be patient.
Now a former TRW or Group 44 with real history is a totally different thing. But you? A 30 year old car with no shop manual of changes you make and any assurance of future parts availability?
I happen to get real lucky when I sold my XJS with the two turbo’s. The buyer was that .1 % and I almost broke even. Much much better than I expected. Of course the 2000+ man hours I spent were lost.
I paid $800 for the car and I have zero none nothing not a single intention to sell it. It would be cool to put the v12 in the xkr, but I like my 4 door. I'll race it everywhere but the City, racing in town is immoral. Let's hope I can do a few good pulls in it much less put it up against another car.
. I'll run a knock sensor and not go too hard on lower octane.
Don't forget that every engine has a unique frequency response where knock occurs, so the knock sensing system has to be designed for each engine. There is no such thing as a universal knock sensor system.
First you'd have to find the knock point by measuring the instantaneous angular acceleration of the crankshaft and then determining what the resonant frequency is at that point. It takes a lot of sophisticated measuring equipment to find knock. Since there hasn't been a Jaguar V12 with a knock sensing system you have a lot of work ahead of you and a lot of dyno time.
If all you want is more power it's much easier to simply increase the displacement.
Don't forget that every engine has a unique frequency response where knock occurs, so the knock sensing system has to be designed for each engine. There is no such thing as a universal knock sensor system.
First you'd have to find the knock point by measuring the instantaneous angular acceleration of the crankshaft and then determining what the resonant frequency is at that point. It takes a lot of sophisticated measuring equipment to find knock. Since there hasn't been a Jaguar V12 with a knock sensing system you have a lot of work ahead of you and a lot of dyno time.
If all you want is more power it's much easier to simply increase the displacement.
You're making it too hard, yes there is a universal knock sensing system, it does take a simple adjustment. And increasing displacement may increase torque but it doesn't make a whole lot more power, and torque doesn't win races.
Ivan dont tell Carroll SHELBY that , one of his famous sayings " TORQUE WINS RACES HP SELLS CARS".
for street racin i'll take torque anytime!
for instance just say you got a nice clean street sedan, without an engine?
you have available TWO engines , one makes 400HP with 450 Torque, at 4000rpm 5L V8!
other is a F1(Formula one) engine, it makes 850 HP but only 200 Ft. lb.at 10,000 rpm!
?? choose carefully?
Lol, I knew my claim that increasing displacement doesn't increase power a lot would get some reactions, but I like seeing my hp wins races claim go uncontested, I would love someone to prove me wrong. IDK what I'm talking about but stroking a 350 to a 383 picks up 20hp and that's so much, and going to 400ci only gains another 10hp. It has to breathe through the heads, and going with anymore displacement with a he head is not worth it unless it's flowing more.
!
you say USABLE HP,
explain how some good racing diesels cant even rev to 5252, and can make 1000ft lbs, at 4000rpm?
i seen it race at Road America , and it beat all comers, including Billion dollar PENSKE factory Porsches, revin11,000revs!
TDI R10 on the straights walked right on past Porsche, Audi rev 4500rpm , and Porsche screamin 11,000K!
torque sure as hell won those races!
which brings to question , Reality is completely different than Theory, theory is lots of talk and BS,+ plus a bunch of numbers , reality is doing it and getting something done? they had the engine banned from any other competition , after the race, no one knew why except Penske was on director board!
Well, update on plans, turbocharging is a long ways away, since I'm looking for stupid numbers like 800hp with lower octane fuel, I'm going to have to increase the flow as much as possible. Also, I want my car to stop a bit better, and turn a bit better, and I want to go fast right now so I'll be putting some energy into my dodge to do a 16v hybrid, that car is soooo much easier to mod lol, have ridiculously low power to weight ratios are obtained cheaply, but it's fwd but hey at least I have it. Since I want to make some power on just motor, going to see what can be done with cams, port work without touching the chamber, and ported intakes. If I can make reasonable gains in flow it will all be so much easier to boost due to lower pressures. Maybe start a fresh thread on porting he heads?
Since I want to make some power on just motor, going to see what can be done with cams, port work without touching the chamber, and ported intakes. If I can make reasonable gains in flow it will all be so much easier to boost due to lower pressures. Maybe start a fresh thread on porting he heads?
Ivan
I admire your can-do approach and I am sure you will have a great deal of fun doing whatever you finally decide on. I seem to remember you have an HE motor? If so (and please do not think I am being difficult or in any way accusing you of dreaming, wanting to put your ideas down, etc etc) in my view porting the HE head is a complete and utter waste of time and will gain you hardly anything. The reason being the valve size is very limited and that dimension is the limiting factor on cylinder filling. Also the tracts in the head are VERY narrow walled and it is easy to break through into the water jacket.
You do have a few other options though:
fitting a 6 litre head on a 5.3 motor reduces the compression ratio quite a bit and thus makes forced induction easier
finding a pre-HE motor might not be that hard, and these are FAR easier to (i) stroke i vastly enlarge capacity and (ii) improve cylinder filling using larger valves, and (iii) use relatively low compression cylinders and thus will take boost far more easily.
The TWR racing XJS used the pre HE motor (never mind what the label said on the boot!) admittedly they were stuck at factory capacity by the rules; but even with everything they could do the improve the breathing, including special valves pistons, etc etc, they had a really hard time getting the pre HE to 400 BHP.
For my money, I am quoting the great Roger Bywater of AJ6 engineering fame who knows more about the Jaguar V12 that probably anyone outside of Allan Scott the TWR engine guru: a 7 litre, two valve, pre HE is easily the best and cheapest way to make big power!
Anyway, go for whatever you decide on say I and have fun doing it!
TWR did at the end of their involvement with Group A racing, they made 510 HP at 7300 RPM. but that was after about 4 years of development. Obviously, lots of non standard parts too. They didn't start from the production engine, either, they used the Broadspeed race cars as a starting point for development.
Broadspeed had potentially cracked the 500hp barrier in 1976/77, although they generally figured they produced 450-480 hp; but those engines had completely redesigned heads and pistons, plus larger displacement. It was a unique combustion chamber design for those 2 cars. So it's pre HE in the sense it was made before the HE engine, but it was not a flat head V12 like in a production car.
Well ****, I guess I won't hit my goals on pump gas without a pre he motor. I guess I could live with 600hp, then if I wanted to do some more I could just do a race fuel tune or e85, problem with that is e85 can sometimes make 1.5x the amount of power that was made on pump, scary huh? And besides, the way I drive my cars, I see myself finding the weak point shortly, I'm pretty good at blowing stuff out. This thread was very helpful, really it was, making me realize he heads move no air, and that few have turboed their he cars and seems like they have survived.
TWR did at the end of their involvement with Group A racing, they made 510 HP at 7300 RPM. but that was after about 4 years of development. Obviously, lots of non standard parts too. They didn't start from the production engine, either, they used the Broadspeed race cars as a starting point for development.
Broadspeed had potentially cracked the 500hp barrier in 1976/77, although they generally figured they produced 450-480 hp; but those engines had completely redesigned heads and pistons, plus larger displacement. It was a unique combustion chamber design for those 2 cars. So it's pre HE in the sense it was made before the HE engine, but it was not a flat head V12 like in a production car.
Jagboi,, you should mention the amount of money spent to get 500+ HP, using 5.3L , i doubt anyone on this site has the funds or will to make it happen!
04-23-2020, 12:08 PM
