XJ XJ6 / XJ8 / XJR ( X350 & X358 ) 2003 - 2009

Quest For 450 Horsepower

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  #261  
Old 01-25-2019, 06:29 AM
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Originally Posted by Etypephil
That's a shame; I considered a similar system a while back, but was quoted around £2,200, which didn't seem especially good value, although the company's work quality looked good.
I have seen some of your other mods mentioned elsewhere on here; what do you think were the most worthwhile, and were there any downsides to them?
Quicksilver have an option:
https://www.adamesh.co.uk/quicksilve...stem-840-p.asp

i have only read one review on this via the x350/358 Facebook group - there didn’t appear to any downsides, and no drone
 
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  #262  
Old 01-25-2019, 05:51 PM
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Originally Posted by Etypephil
That's a shame; I considered a similar system a while back, but was quoted around £2,200, which didn't seem especially good value, although the company's work quality looked good.
I have seen some of your other mods mentioned elsewhere on here; what do you think were the most worthwhile, and were there any downsides to them?
Pretty much all the mods done were worthwhile and work well together. I did also change the IC pump for a AMG one, I need to work on the S/C coolant circuit to get the benefit.
The Caldoofy intake is a great mod to have, just for the engine bay bling & extra S/C whine. The 200 cell cats were worthwhile at the same time as the exhaust, though it needs to be hot to get through MOT emisions. No other real downsides, the car can easily average mid 30s MPG on a run and must be running at least around the 450bhp mark now.
 
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  #263  
Old 01-25-2019, 08:11 PM
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I can now offer a very good quality cat back exhaust to fit the x350/8 XJR for £1200 delivered to the UK or fitted for free if you come up to Newcastle upon Tyne.
The system is 2.5 inch and has an X pipe in place of the front silencers then on to two small silencers that sit just before the rear diff, then on to two larger rear boxes finished with 4 inch slash cut tail pipes that are on slip joints to allow perfect alignment with the rear bumper.

The exhaust offers a nice time with no drone when cruising. I now also have four branched manifolds fitted to my car and am awaiting getting a slot on the Dyno for after results!
 
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  #264  
Old 01-26-2019, 04:56 PM
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Hmmmm nice, but looky expensive!
 
  #265  
Old 01-27-2019, 12:34 PM
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If that is for a brand new system, then that is a really good price actually.
 
  #266  
Old 01-27-2019, 01:29 PM
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Originally Posted by alecescolme
If that is for a brand new system, then that is a really good price actually.
Thanks, I thought so too when compared to mina and paramount prices.

They are brand new made to order, when my exhaust was off for manifold fitting had a jig made up using my exhaust as template.
 
  #267  
Old 01-27-2019, 04:29 PM
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Originally Posted by viper1996
Meth injection is waste if you cant tune for it...Adds 0 HP...
I recant this statement Jackra. Drive an "R" in the summer as opposed to winter temps here up north and the performance is greatly enhanced with the dry cold air. I am thinking that the meth will keep the intake charge much lower giving you that same winter power level in the heat of the summer or at least close...Folks that live in warm climates year round don't know how much stronger an R pulls on a dry 20 degree day!
 
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  #268  
Old 01-27-2019, 05:44 PM
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Originally Posted by viper1996
I recant this statement Jackra. Drive an "R" in the summer as opposed to winter temps here up north and the performance is greatly enhanced with the dry cold air. I am thinking that the meth will keep the intake charge much lower giving you that same winter power level in the heat of the summer or at least close...Folks that live in warm climates year round don't know how much stronger an R pulls on a dry 20 degree day!
Thats what someone else stated.

I also think it helps keep the SC chargers and elbow below the TB clean. As I stated before my charge coolers and elbow were very "gunged up" with soft carbon and my charge coolers were probably less than 20% efficient because of that.

Thats why I say for anyone wanting a performance improvement they need to clean out all that crap after about 60-80k miles or they waste money on other improvements.

I went for a drive today the first time since new rear tires a couple of weeks ago. I replaced my Summer tires with all season. I get wheel spin when I am doing 30 mph and I do not have to floor it at all. With an LSD thats both wheels.

Ground was pretty cold and the traction rating on my new tires is not as good as the old Summer tires which would have been lousy anyway on the cold surface.

I am taking the car in for emissions tomorrow so wanted to make sure all was ok.
 
  #269  
Old 01-28-2019, 12:57 AM
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Originally Posted by caldoofy
I can now offer a very good quality cat back exhaust to fit the x350/8 XJR for £1200 delivered to the UK or fitted for free if you come up to Newcastle upon Tyne.
The system is 2.5 inch and has an X pipe in place of the front silencers then on to two small silencers that sit just before the rear diff, then on to two larger rear boxes finished with 4 inch slash cut tail pipes that are on slip joints to allow perfect alignment with the rear bumper.

The exhaust offers a nice time with no drone when cruising. I now also have four branched manifolds fitted to my car and am awaiting getting a slot on the Dyno for after results!
That does look good, especially coupled with the new manifolds. Before and after dynamometer results would be interesting. I could be tempted. I also like the look of your intake pipe, the standard one appears to be designed with sound attenuation rather than flow in mind.
 
  #270  
Old 01-28-2019, 01:00 PM
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Originally Posted by Etypephil
That does look good, especially coupled with the new manifolds. Before and after dynamometer results would be interesting. I could be tempted. I also like the look of your intake pipe, the standard one appears to be designed with sound attenuation rather than flow in mind.
The standard intake is very much all about reducing noise, and contains a few design issues that reduce or interfere with flow, corrogated section, indentation by the expansion tank etc, the tube obviously removes these.

Before dyno result on my car with my intake, wot flap removed, exhaust, Cambo remap, 6% pulley and 200 cell sport cats was 352 at the wheels (lower by 10whp than the last dyno at a different place) however I will be going back to the same rolling road this week to get the after run for the manifold for as fair a comparison as possible).
 

Last edited by caldoofy; 01-28-2019 at 08:06 PM.
  #271  
Old 08-06-2019, 03:49 PM
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Does anyone know if the fuel rail on an XJR has a schrader valve? Savvy owners will no what I am up to!
 
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  #272  
Old 08-06-2019, 04:29 PM
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Originally Posted by caldoofy
The standard intake is very much all about reducing noise, and contains a few design issues that reduce or interfere with flow, corrogated section, indentation by the expansion tank etc, the tube obviously removes these.

Before dyno result on my car with my intake, wot flap removed, exhaust, Cambo remap, 6% pulley and 200 cell sport cats was 352 at the wheels (lower by 10whp than the last dyno at a different place) however I will be going back to the same rolling road this week to get the after run for the manifold for as fair a comparison as possible).
Forgot to close this off, the after gain was 30whp and a healthy increase in torque further up the rev range. Only thing changed was addition of manifolds.
Downside is that it is now running lean at the top end on the open loop wot preset map so needs a bespoke map to get the best out of it.

​​​​​​More to come.......
 
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  #273  
Old 08-06-2019, 07:23 PM
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Come on Jackra You gotta know the answer!!!
 
  #274  
Old 08-06-2019, 08:06 PM
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Originally Posted by viper1996
Come on Jackra You gotta know the answer!!!
I confess I have no idea other than you want to mess with the fuel pressure some how?

Maybe just too tired after a day doing bodywork on my old Dakota truck that my stepson messed up.
 
  #275  
Old 08-06-2019, 08:15 PM
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Originally Posted by jackra_1
I confess I have no idea other than you want to mess with the fuel pressure some how?

Maybe just too tired after a day doing bodywork on my old Dakota truck that my stepson messed up.
Haa... fuel tap for nitrous?!
 
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  #276  
Old 08-06-2019, 09:39 PM
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How would the rest of the car hold up to nitrous?
 
  #277  
Old 08-07-2019, 01:07 PM
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Originally Posted by viper1996
Haa... fuel tap for nitrous?!

Sure does. I had bought an adapter fitting for the schrader valve for the drivers' side fuel rail, but they ended up using the passenger side rail. I'll see if i can get a better picture of the actual connection at the fuel rail.


 
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  #278  
Old 08-07-2019, 01:42 PM
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Jazzy it looks like you might be running nitrous yourself? Thanks for that info appreciate it
 
  #279  
Old 08-07-2019, 01:58 PM
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Well my quest for 450 horsepower is over I just ordered is Zex Nitrous kit has lots of great built-in safeguards so you will not damage your engine Amazon has the system on sale for $410 plus tax free shipping one day... I will post pics once I install it. If it works well I'm going to add a bottle gauge automatic bottle warmer, remote opener, and a Nitrous Express EZ maximizer. This is basically going to be used for 60 roll acceleration
 
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  #280  
Old 08-07-2019, 01:59 PM
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