I recently acquired a 2003 XJ8 Sport with just over 100K.
I am looking to make some modest performance upgrades, considering the following:


1. Cold Air intake and filter from Mina Gallery


2. Upgrade replace muffler and pipes: with X pipe after the CATs and larger diameter pipes and mufflers from Catback.


If anyone has any knowledge of these items or a "better way," I would appreciate the help.


Many thanks,
GI Joe

 

How to improve performance of an XJ8 :

1) Sell XJ8
2) Purchase XJR

 

And that's the truth!

 

Uhh. Thanks. I guess.

 

I have a Mina Gallery intake pipe that I am selling at a deep discount. If you are interested, PM me.

 

Your exhaust mods would sound great and give you some kick. The intake is where they are choked. When I had a Vanden Plas, I put on the biggest cone filter that would fit after ripping the air box off.

It gave the sound I liked, and more pull, especially from the mid range onwards. A smooth intake pipe will help, as well as replacing the damn throttle body intake. You can find a
90' tube at most auto parts stores.

There's quite a few companies online that offer silicon tubes, bends and cobra head shaped ones (fit under hood without flow restriction.

I think the name of the company was silicon performance online or silicon performance tubes, something like that. It's not going to give you a huge increase but it makes them much more fun to drive (and hear).

Enjoy you're Jag. There very addictive cars.

 

Siliconeintakes.com possibly

 

I did not mean my previous answer to be glib. The fact is, there are limited options to improve the REAL performance of a NA XJ8. Better sound (more noise), prettier engine compartment and so on are available, but without a change of heads, cams, or other major engine features, there apparently is just not much there. Jag did a good job of getting what the engine will do.
For the same $2000. yu will spend on signficant upgrades, you can swap to an approximately equal XJR and have the real deal.

 

That's the company!

 

I got the same answer decades ago when I called up Dale Walker for advice on my 900 Ninja. I wanted head work, big valves, big cams and big bore piston kit. He asked what I was trying to do? I said make it fast.

He answered "Sell it, and buy a faster bike."

Since he was a profession motorcycle drag racer who set and broke 1/4 times on pro Kawasaki rides and also set records on top fuel bikes, anything was 'Slow' to him.

After the mods, my bike was insanely fast, to me. Everyone has their own definition of fast. The exhaust and intake mods will give you a cool, bad *** sound and you'll enjoy driving it more.

You could also junkyard supercharge it. There's always XJR XKR blowers & intercoolers on Ebay. Someone in the XK8 section successfully installed and is happily running a supercharged XK8 at a softer boost. He put on a bigger pulley.

I've seen take offs for $500 complete. Sometimes less...

 

$500? That is just for a take of SC that may or may not be OK. Lots more to be spent in time and money to put a SC on an NA car. And the XJ8 tranny is notoriously weak and the XJR has a Merc truck tranny that is fairly bullet proof.

That is a difficult and expensive mod to do by the time you get all the computers talking to each other properly, it really is better and usually cheaper to just buy an XJR.

This for your exhaust: https://www.jaguarforums.com/forum/x...ut-outs-68743/
Vector

 

I understand your point, and I am quite sure you are correct... I will be content with modest HP gains from the cold air intake and next fiddling a little with the exhaust. I am not going to change the headers or rig up a charger, etc... just wanted to know that: a. I was on the right track, b. If there were any "typical" means of doing it.


I do however have an 1984 XJS/HE... That is the car I will (eventually) make some mods to improve. Once I figure out why I have a drain on the battery that, causes random stalls at speed and can drain the battery in minutes so that it will crank but not turn over without a quick jump... very distressing.

 

Thanks, I will check it out.

 

You're absolutely right. This is meant as bar stool/cool engine builds talk.

It would be best to tear into the blower and replace seals and/or bearings, but the intercoolers you could just clean.

I don't expect anyone to do this lightly, but for the guy who can't afford it, but has an old XJ8, XK8 it's a real option that one of our members, JagxkFan did three years ago changing the supercharger speed with a larger pulleys. I've seen quite a few M112 with intercoolers and other parts sell for under $500 on Ebay, and less if you buy them piece by piece.

I believe two others did it as well but went full gonzo with forged pistons, etc...to run 12+ lbs of boost. JagxkFan (I tried to include the link but couldn't with my phone) just wanted more hp and was happy with the increase (half the hp\torque gain it would normally give) and was able to do it on the down low.

Pretty cool.

I think it will be in more and more cars of the future, these soft boost applications. Saab did it with their turbocharged 4 cylinders for over a decade. Not going for impressive hp figures but just a bigger engine feel with less of the lag turbos normally have.

Higher compression + lower boost gave them better throttle response and better fuel economy.

 

The OP has a NA XJ8 with no supercharger, so no seals or bearings to replace or intercooler to clean.

A smaller, not larger, upper pulley increases boost. You can change the lower one too, but that would give you way too much boost for a NA engine to handle.

And you can't just bolt a supercharger on a NA Jag engine and fire it up.

It's not the SC parts availability or cost but getting all the other parts of the car that go along with it that is the challenge: a second fuel pump in the tank and the wiring and sensors to turn it on when needed, beefier tranny, no variable valve timing on the NA engine, higher stock compression on the NA engine that limits what you can do with boost, different computer modules....

It goes on, but I will stop here and tell you again that it is easier, cheaper, and more reliable to just buy an XJR.

Try searching "adding a supercharger" on the forum and you will see what I mean.
Vector

 

Thanks for the insights. Clearly, this topic has had a lot of prior attention..
I think I will settle for the modest improvement from the Air Intake and the exhaust to wake up a few inactive horses in the engine.. that's good enough for me with this car.


The '84 XJS I have is another story and one, I want to (eventually) kick into another gear - so to speak.


I appreciate the insights.
Joe

 

I'll check out the search Victor and see what comes up. I only saw JagxkFan pull up and the modded engine member come up.

I wish I could link JagxkFan's build up. I don't think he did anything but install the blower package. It's big on the BMW sites for their V8 owners. By going with a larger pulley, they are reducing the boost to address all the other needed mods you mentioned to run full boost.

 

they do have some truth to what they are saying tho.. also not very helpful at all

 

Waiting 5 years to reply is not very helpful.

 

6 years but, who’s counting? Haha!