One for the technical experts...

One for the technical experts...

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groomi

Original Poster:

9,323 posts

250 months

Tuesday 24th October 2006
quotequote all
An interesting post over on General gassing from a new member claiming 500bhp on an X308 XJR. Myself and one or two others are rather sceptical at this, but in the absence of more learned opinions we're not getting any closer to finding out if it's true or not.

www.pistonheads.com/gassing/topic.asp?p=1&f=23&t=318920&h=0

Any thoughts?

GavinPearson

5,715 posts

258 months

Tuesday 24th October 2006
quotequote all
If you put enough boost in, use high enough octane fuel, and can flow icy cold water through the chargecoolers it is probably possible.

What we did for the XK180 was use a separate circuit for each chargecooler, made a smaller supercharger pulley, and the engine made 450 bhp on pretty much the standard engine management software.

The issue is though that as the car drives the chargecooling system heats up, eventually the air inlet temps rise and the power cannot be sustained.

One thing I noticed was that the conversion used a different crank pulley - I know that it probably 'works' but the pulley is actually a torsional vibration damper so when you change the way it works, you run a risk of breaking a crank...

If you want to make the engine deliver a reliable and sustainable 500 bhp especially in summer weather I think you would need to do far more than was done on this vehicle, but I haven't seen anything other than pictures and claims, so I can't know for sure.

a8hex

5,830 posts

230 months

Wednesday 25th October 2006
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There was a similar thread back in the middle of August. See "RE: TUNER TWEAKS FOR JAGUAR XK" in particular Jagman (AKA Chas from Raceing Green Cars) talks about some what's involved in getting big power from these engines and some of the likely costs.

Trooper2

6,676 posts

238 months

Wednesday 25th October 2006
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I'm not as skeptical about the horsepower claims as I am about the fuel mileage claims.

groomi

Original Poster:

9,323 posts

250 months

Wednesday 25th October 2006
quotequote all
Trooper2 said:
I'm not as skeptical about the horsepower claims as I am about the fuel mileage claims.


yes

NormanD

3,208 posts

235 months

Wednesday 25th October 2006
quotequote all
Trooper2 said:
I'm not as skeptical about the horsepower claims as I am about the fuel mileage claims.


I've got the same tricks done to my XKR, would only claim 450BHP though.

Only get 16 - 18 MPG on an enjoyable run though!!

a8hex

5,830 posts

230 months

Wednesday 25th October 2006
quotequote all
NormanD said:
Trooper2 said:
I'm not as skeptical about the horsepower claims as I am about the fuel mileage claims.


I've got the same tricks done to my XKR, would only claim 450BHP though.

Only get 16 - 18 MPG on an enjoyable run though!!


It's not hard to get that on an "enjoyable" run on my 3.2 X300.
Actually just over 18 used to be my average when I was only living about 5 miles from the office I visited most often. But hey, when the wife had a 1.8L Passat (not turbo one, just the boggo std one) that only managed about 22 on the same sort of driving. So let's think about this.... XJ6 18.5MPG ... Passat 22MPG... nah sod it, I'll take the Jag, no contest.