sumpcracker
Posted a lot
Yes, I’m still here.
Posts: 1,751
|
|
May 25, 2010 22:18:30 GMT
|
|
Does anyone here know about jag v12 engines, i have a series 1 daimler double six swb, which has the early low hp engine.
only 253hp from 5.3 ltrs! the series 2 has 280ish, where does the extra come from? and i think the injected series 3 is 295hp.
where do i go? bigger carbs? (x4) i have 1.5 inch zenith/stromberg.
Maybe a charger ?
|
| |
|
|
stealthstylz
Club Retro Rides Member
Posts: 14,856
Club RR Member Number: 174
Member is Online
|
|
May 25, 2010 22:40:02 GMT
|
Not sure on specifics, but a friend of a friend has a Cobra with a 650bhp n/a V12 in it. Think he's having custom heads made so it'll be 750bhp lol.    Matt |
| |
|
|
sumpcracker
Posted a lot
Yes, I’m still here.
Posts: 1,751
|
|
May 25, 2010 22:43:53 GMT
|
|
Well, i just read that my engine is 272hp not 250, i was looking at us figures.
i keep reading that 350 is easy to acheive n/a but i cant find anywhere that says how.
I'm guessing heads/carbs/exhaust but i have no specs.
|
| |
|
|
sumpcracker
Posted a lot
Yes, I’m still here.
Posts: 1,751
|
|
May 25, 2010 22:45:46 GMT
|
|
I see your mate has 6 downdraught carbs, sexy...nice cobra.
|
| |
|
|
10mpg
Club Retro Rides Member
Posts: 4,253
Club RR Member Number: 204
|
|
|
|
Your lucky the early pre HE heads are the ones to have to make power, apparently there are big gains to be had in the inlet manifolds, which you can cut and shut and fit trumpets to, a good exhaust system helps no end as does a decent fuel system I think downdraughts/TB's make the best power but stadalone managemnt on an HE injection system can work well if you enlarge the runners and TB... hang on looky here: www.jagweb.com/aj6eng/v12_performance.html |
| |
The Internet, like all tools, if used improperly, can make a complete bo**cks of even the simplest jobs...
|
|
|
|
|
|
|
|
Search for "Wolf Direct Racing" they are a V12 performance specialist.
The pre HE is the best engine to start with, with slightly higher compression and decent fuel injection it easily comes up to over 300bhp. Get rid of the silencer mid boxes as they're useless and sap power.
The Stromberg carbs on the series 1 V12 aren't the greatest thing in the world, so you need to look to either fuel injection or better carbs. I've seen the downdraught kits but the low bonnet on a Jag means you are limited by space.
You can but better cams from places done to fast road spec, which increase the lift, and duration... but go too high and you need to start modifying the cam covers, as they won't fit over them! TWR found that out...
The way of making the car much quicker to start with would be ditching the ancient three speed auto. Get a manual box and clutch off a five speed XJS, A bellhousing from a V12 manual E-type, and an adaptor plate. It'll transform the beast.
|
| |
"You're about as likely to come across a fully functioning old Jag, as you are a taxicab that smells agreeable." - James May
|
|
|
|
|
May 26, 2010 22:46:45 GMT
|
swap the strombergs with SU type carbs - strombergs were only fitted as they met the emissions easier, SU's give a smidge more power straight out, and apparently driveability improves too a better designed intake would work wonders - but if you're keeping the bonnet standard, you're pretty much out of luck on that one Decent exhaust headers are a must - the pre HE cast manifolds are naff to say the least! Keep the auto if it's a TH400, as with a mild rebuild, they're good for 600+Bhp (upto 1000Bhp if you spend some pennies) plus, you can get what's called a "reverse manual valve body" for the 'box, which means instead of getting D, 2, 1 - you get...1..2...3.. not automatic either, if you drop into 2nd, at 100mph.... it WILL go into second! Makes it more like a manual  I'm going to be 'charging my V12, but really want some pre-HE heads, and carb manifolds. The injection manifolds, are naff |
| |
You're like a crazy backyard genius! |
|
|
|
|
May 27, 2010 21:57:57 GMT
|
my dad has a 300bhp factory tuned TWR 6 litre xj12, can't be many about now  |
| |
|
|
|
|
|
|
|
|
Given that for a limited time in the early Series 3 XJ12 production there was a 10.5 : 1 compression ratio for a short while kicking out about 300bhp, I would hope the TWR car has a little more than that. Even the bog spec 6 litre XJS had 323bhp!
|
| |
"You're about as likely to come across a fully functioning old Jag, as you are a taxicab that smells agreeable." - James May
|
|
