Twin Turbo V12 project.
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From: WV
aside from the fact that i really dont like V8's mostly its just that its a 75 (when smog and lower compression were choking everything)
it would make a great turbo project (8:1 compression), but it wasnt worth the T.M.E. IMHO.
also, i really just cant emphasize enough how much i adore the L67 and L32.
Last edited by M90power; Feb 1, 2013 at 09:14 PM.
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From: Northern Ohio
Hi Ian,
Oddly enough, I plan to do exactly what you have in mind on my V12 test stand in order to avoid all of the complexity required with the FI setup. I only want to run an engine with some of the mods I do in order to check things out before installing in a car. A couple years back, there was a person on ebay who actually made some very good looking intake manifolds for two four barrel carbs for the 5.3L V12. My issue with the set up was the smallest carbs available are the 450 cfm Holley which would total 900 cfm. The engine would have to be highly modified to run well with that much carb and driveability may be iffy on the street. I have a friend with a cobra replica which has a highly modified 351C with a Holley Dominator which is around 1000cfm and at any other mode other than WOT, you could run a Ford Pinto on the exhaust. A couple of Holley two barrels might be more appropriate. The hood clearance is almost nonexistent above the manifolds, a couple of bulges will cure that. Be advised I'm not an hp engine builder, just offering things I've come across.
Well, I'll be darned. Look what I found, Jaguar V12 Dual Quad Intake Manifold XJ12 XJS | eBay
Oddly enough, I plan to do exactly what you have in mind on my V12 test stand in order to avoid all of the complexity required with the FI setup. I only want to run an engine with some of the mods I do in order to check things out before installing in a car. A couple years back, there was a person on ebay who actually made some very good looking intake manifolds for two four barrel carbs for the 5.3L V12. My issue with the set up was the smallest carbs available are the 450 cfm Holley which would total 900 cfm. The engine would have to be highly modified to run well with that much carb and driveability may be iffy on the street. I have a friend with a cobra replica which has a highly modified 351C with a Holley Dominator which is around 1000cfm and at any other mode other than WOT, you could run a Ford Pinto on the exhaust. A couple of Holley two barrels might be more appropriate. The hood clearance is almost nonexistent above the manifolds, a couple of bulges will cure that. Be advised I'm not an hp engine builder, just offering things I've come across.
Well, I'll be darned. Look what I found, Jaguar V12 Dual Quad Intake Manifold XJ12 XJS | eBay
Knojag,
Holley makes a 390 cfm 4bbl that works nicely on a dual quad manifold for smaller displacement engines!
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From: Austin tx and Daytona FL.
on another post, you could just buy a GM Chevy 572" crate motor, they is 9.4L of engine, and they even come with a warrenty.
and cost less than what you trying to accomplish.
but to each his own.
and cost less than what you trying to accomplish.
but to each his own.
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From: new york
Sure Chris,
From memory it used flat heads, pre HE, with bigger valves.
Bigger displacement liners with Ford Transit van pistons to get us to 5.7lt
The throttle bodies machined out, with new spindles/butterflies.
The 16CU ECU went to AJ6 Engineering to cure a delay in throttle pedal response.
We also used 6.0lt injectors from a JaguarSport unit. Although another trick is to use two sets of AJ6 injectors.
A free flow s.s.exhaust, I think 2.5" straight through.
Maybe not a fair fight, but a friend showed up with a brand new XKR Silverstone, the only UK supplied car in Black, and it ate it for lunch, I'll always remember the supercharger whine fade into the background. A lighter car in the E Type, it walked away.
Here's a shot of the 6.1 lay-up, pre build. Nice thing about this is the modem telemetry - I can alter the mapping on track. Again installed in an E Type. 550bhp standard, 650bhp without issue.
Final shot is of another V12 5.7 with custom installed deep case 5 speed, with an aluminium flywheel. Harvey Bailey torsion bars, Koni adjustable dampers, AP racing brakes, with custom Dayton SS wheels. Nothing really standard about what we did to these cars, including leather hood tonneu's, the list goes on, retro-development, in a little workshop somewhere....
From memory it used flat heads, pre HE, with bigger valves.
Bigger displacement liners with Ford Transit van pistons to get us to 5.7lt
The throttle bodies machined out, with new spindles/butterflies.
The 16CU ECU went to AJ6 Engineering to cure a delay in throttle pedal response.
We also used 6.0lt injectors from a JaguarSport unit. Although another trick is to use two sets of AJ6 injectors.
A free flow s.s.exhaust, I think 2.5" straight through.
Maybe not a fair fight, but a friend showed up with a brand new XKR Silverstone, the only UK supplied car in Black, and it ate it for lunch, I'll always remember the supercharger whine fade into the background. A lighter car in the E Type, it walked away.
Here's a shot of the 6.1 lay-up, pre build. Nice thing about this is the modem telemetry - I can alter the mapping on track. Again installed in an E Type. 550bhp standard, 650bhp without issue.
Final shot is of another V12 5.7 with custom installed deep case 5 speed, with an aluminium flywheel. Harvey Bailey torsion bars, Koni adjustable dampers, AP racing brakes, with custom Dayton SS wheels. Nothing really standard about what we did to these cars, including leather hood tonneu's, the list goes on, retro-development, in a little workshop somewhere....
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From: Roseville, MI
That is sexy..... Damn that looks good.
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From: las Vegas
Big Block Chev
I too looked at M90 and Toyota SC14 although to have everything mounted under the bonnet would require using 2 -- one on each bank. There is a guy here in Aus that has mounted 2 SC14's to a V12 said it was a relatively easy mount. 1 M90 would not be big enough to feed the V12 you could use an M112 but would need to stick it up through the bonnet on a custom manifold
There are no kits currently available that I know of so everything will need to be custom.
I decided to go CSC with a capacity increase. I need to replace the pistons anyway so may as well offset grind the crank to 84mm stroke and using chev small journal rods means I don't need to have the crank welded and ground. Chev rods good for 500hp in a V8 will be good for 750hp in a V12 (hp per pot).
Subaru pistons are the right size 93mm is about as much as the V12 can be bored without replacing the liners. If you replace the pistons the liners will have to be honed anyway as the piston and liner are a matched set. The Subie pistons can take 350hp all day in a 4pot (1000hp in a V12) and are very cheap for the HPC (NOT forged). The wrist pin will need to be machined with the rods to fit and the rods machined to fit the crank. But with this done 700hp will be acheivable with reliability.
Here are some pics of a twin turbo V12 here in Sydney
I too looked at M90 and Toyota SC14 although to have everything mounted under the bonnet would require using 2 -- one on each bank. There is a guy here in Aus that has mounted 2 SC14's to a V12 said it was a relatively easy mount. 1 M90 would not be big enough to feed the V12 you could use an M112 but would need to stick it up through the bonnet on a custom manifold
There are no kits currently available that I know of so everything will need to be custom.
I decided to go CSC with a capacity increase. I need to replace the pistons anyway so may as well offset grind the crank to 84mm stroke and using chev small journal rods means I don't need to have the crank welded and ground. Chev rods good for 500hp in a V8 will be good for 750hp in a V12 (hp per pot).
Subaru pistons are the right size 93mm is about as much as the V12 can be bored without replacing the liners. If you replace the pistons the liners will have to be honed anyway as the piston and liner are a matched set. The Subie pistons can take 350hp all day in a 4pot (1000hp in a V12) and are very cheap for the HPC (NOT forged). The wrist pin will need to be machined with the rods to fit and the rods machined to fit the crank. But with this done 700hp will be acheivable with reliability.
Here are some pics of a twin turbo V12 here in Sydney
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From: Houston, TX
don't want to hijack...
- replace the 3 speed slush box with something modern
- gut the exhaust if you can get away with it
- get growlers or a cold air intake
I think that's all the low-hanging fruit, my friend. Everything else is gonna co$t. You might shave a couple of seconds off your 0-60, but even so... any modern car with even modest sporting aspirations is gonna kick your ***.
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From: las Vegas
... so I'll keep it short. Seems that the consensus is:
- replace the 3 speed slush box with something modern
- gut the exhaust if you can get away with it
- get growlers or a cold air intake
I think that's all the low-hanging fruit, my friend. Everything else is gonna co$t. You might shave a couple of seconds off your 0-60, but even so... any modern car with even modest sporting aspirations is gonna kick your ***.
- replace the 3 speed slush box with something modern
- gut the exhaust if you can get away with it
- get growlers or a cold air intake
I think that's all the low-hanging fruit, my friend. Everything else is gonna co$t. You might shave a couple of seconds off your 0-60, but even so... any modern car with even modest sporting aspirations is gonna kick your ***.
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From: Vic Australia
If you have a pre HE low boost (6-8psi) turbo charging can be reasonably cheap. If you have a HE then turbo's are not an option without lowering the CR, this requires custom pistons or a set of 6.0L pistons in the 5.3L, either option will cost most of your budget.
Any way you look at it to get a 12 second car will cost $$$. 12 cylinders means 12 or 24 of everything.
I live in Australia so I can only advise budget based on my location and I have budgeted $10,000AUD to rebuild my 5.3L into a 6.0L with power expectations of around 450hp.
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From: las Vegas
First you need to add your cars details to your signature. There are 4 different iterations of the V12 in the XJS, all completely different.
If you have a pre HE low boost (6-8psi) turbo charging can be reasonably cheap. If you have a HE then turbo's are not an option without lowering the CR, this requires custom pistons or a set of 6.0L pistons in the 5.3L, either option will cost most of your budget.
Any way you look at it to get a 12 second car will cost $$$. 12 cylinders means 12 or 24 of everything.
I live in Australia so I can only advise budget based on my location and I have budgeted $10,000AUD to rebuild my 5.3L into a 6.0L with power expectations of around 450hp.
If you have a pre HE low boost (6-8psi) turbo charging can be reasonably cheap. If you have a HE then turbo's are not an option without lowering the CR, this requires custom pistons or a set of 6.0L pistons in the 5.3L, either option will cost most of your budget.
Any way you look at it to get a 12 second car will cost $$$. 12 cylinders means 12 or 24 of everything.
I live in Australia so I can only advise budget based on my location and I have budgeted $10,000AUD to rebuild my 5.3L into a 6.0L with power expectations of around 450hp.
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From: Houston, TX
red12, your question definitely deserves its own thread.
- go to the XJS forum
- click the "post new thread" button
I was looking around on eBay earlier, and man you can pick up a 12 cylinder BMW or Mercedes drivetrain cheap - even the twin turbo versions. Might be cheaper to lump one of those than to hotrod the Jaguar V12. And way more interesting than a Chevy (no offense to Chevy lumpers
)
Anyway, back on topic.
- go to the XJS forum
- click the "post new thread" button
I was looking around on eBay earlier, and man you can pick up a 12 cylinder BMW or Mercedes drivetrain cheap - even the twin turbo versions. Might be cheaper to lump one of those than to hotrod the Jaguar V12. And way more interesting than a Chevy (no offense to Chevy lumpers
)Anyway, back on topic.
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From: Minnesota
I see this thread has popped up again. At the time when this thread had quite an active, I was also seriously considering the twin turbo option for my ‘88 XJS. I really feel there is great potential in that configuration. Did quite a bit of research on the project. Talked with Ross pistons when I was at SEMA about a custom set of lower compression pistons. Looked into Mega Squirt for the EFI controller. Contemplated fabricating an intake manifold. I own a company that built custom headers that now sells the components, so I was going to build a set of turbo headers. Picked up a pre HE engine for the build. Unfortunately the project got side lined, but I still look forward to breathing life back into it again. It sure would be great to see some more posts on the subject. The engine I had slated for the build is in the images below with a set of headers we built for a customers XJ13 kit car project. I know it doesn’t directly relate to this topic, but I thought some might find it interesting. If anyone needs help with header part of a twin turbo project, I would be more than happy to help out, even if they buy all of the parts from somewhere else. I am on my 3rd XJS, so I have real passion for these cars.
(I tried to load those pictures below my post. Excuse my inexperience)
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From: Minnesota
It was for a kit car XJ13. Similar to the one in the following link:
Jaguar XJ13 V12 Prototype Sports Racer (1966) ? Old Concept Cars
Jaguar XJ13 V12 Prototype Sports Racer (1966) ? Old Concept Cars
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From: Austin tx and Daytona FL.
i have always liked the XJ13!
are you building in fiberglass body or aluminum /riveted?
i seen one in Florida a few yrs back, Red fiberglass, pre-HE 6 webers, used a porsche transaxle, custom aluminum floor platform.
nice road worthy car, guy was going to sell some finished or kits, dont know if he ever did tho.
are you building in fiberglass body or aluminum /riveted?
i seen one in Florida a few yrs back, Red fiberglass, pre-HE 6 webers, used a porsche transaxle, custom aluminum floor platform.
nice road worthy car, guy was going to sell some finished or kits, dont know if he ever did tho.
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hey, thanks for the reply. youve got some great info there. i havent bought the car yet. i wanna start off with the most ideal car, instead of buying one and stuggling with it.
so according to you i would be better off boosting a non H.E. v12? and why is it limited to 6psi? is that really all the headgaskets can handle? im assuming this engine, since it is E.F.I. has got a map sensor? if so, can the map sensor understand boost figures?
thanks again.
so according to you i would be better off boosting a non H.E. v12? and why is it limited to 6psi? is that really all the headgaskets can handle? im assuming this engine, since it is E.F.I. has got a map sensor? if so, can the map sensor understand boost figures?
thanks again.
You dont have to waste a lot a lot of money and time to get there. It’s not some blue Sky dream. Pull the stock pistons and double the ring gap. The engine is happy.. if you have the early Bosch fuel injection a $85. FMU will work. Just increase the easiest injectors 60% by volume to handle the E85.
The early distributor works. 10 at idle 40 at 3500 rpm The E85 keeps everything cool preventing preignition. Alcohol has a slower flame front which drives the piston further down
the bore.
The Borg Warner transmission won’t live. But you can swap a manual transmission in which will the later Turbo 400 can be made to survive. But it’s a 3 speed OK on the street but not racing.
Last edited by Mguar; Sep 12, 2019 at 11:55 PM.