This is the post I was looking for when I joined this board, a list of low cost, proven mods, actually tried by a non-biased individual, who then used the same honest performance measures before and after under the same conditions. I am including before and after dynos from the same dyno under the same conditions, and actual 1/4 mile times and mph results. My car is a 2002 Jaguar XJR with 55,000 miles on the clock.

I hope to preserve this post on this board, so those who are new to these cars may have the benefit of an honest, unbiased post. I say this because, I have found that many sellers of performance upgrades knowingly and intentionally lie/overstate the gains of what they sell, and blow a lot of smoke trying to say you can't economically get 12 second 1/4 mile power levels with an Eaton. Well, actual real world performances prove you can.

I ran 2 almost identical baseline 1/4 mile times and speeds, one with traction control on and rolled into the throttle, and one without traction control, no wheelspin on either run: 13.839 @ 101.61 and 13.876 @ 100.46. Given how close and consistent the runs were, I consider these a solid baseline. When I've completed my "after" runs on May 22nd, I'll post my times/speeds again.

Between the before and after mods, not knowing if I was risking the motor by going too lean, I removed an existing (previous owner) overly aggressive ECU tune with an aggressive timing advance and tuned for power (AFR of 13.5-12.8) which lost approx 18 RWHP as judged by reports from other board members results on a dyno. Honesty dictates that some of those losses must be added back to have an honest "after" HP figure to show the actual gains from the mods. I am therefore using a very conservative guesstimate of a loss of only 10 rwhp.

3/1/14 updated and removed cost of parts that did not add any power
List of Mods: and cost to duplicate today:
$400 Upgraded from stock 75mm MAF->92mm Pro-M MAF
$150 3.5" intake tube and silicon parts from siliconintakes.com home made
$100 Had Maxbore.com bore out my stock 75mm TB to 82.5mm , I port matched the elbow to 83mm (self)
$200 Gen V Eaton M112 with +1.8lb pulley (cost just to add pulley)
$ 25 ported intake manifolds and charge coolers, and intake to blower slightly ($25 for abrasives consumed)

$875 for approx +50 HP= $17.50 per HP

update 5-23-2013: I ran the 1/4 mile yesterday and improved my best time by .606 seconds and mph by 3.91 mph! to a best of 13.233 @ 105.34 mph. This was on the same street tires, but this time, traction, or lack thereof was a significant limitation. This means with better traction my times would have been better.

Here is the video of that run: 2002 Jaguar XJR @ 13 psi quarter Mile 1/4 13.233 105.34 mph - YouTube

The following dyno show my highest run before my mods, and the highest run after. The caption says 104 octane, but the best "after" run was on 91 octane, the same as the before run.

I'm only dealing with the top end gain numbers, since the spikes of HP/TRQ lower in the rpm band are subject to unequivilancies of throttle on times, etc, etc. and are subject to too much debate. The fact that I gained .6 seconds and 3.91 mph says the dyno is reading low on the gains, as real world results squish all theories, regardless of all the arm waving that has been done to blow smoke, and proves that the gains were larger than the dyno shows, and the fact that the boost coming on sooner is a big deal in the real world. This makes a BIG difference, having the boost come on sooner, dynos do not show how this makes the car much faster in the real world.

Top end gain 31.9 +10 (estimate of probable losses from deleting ECU tune)=42 /.83 to convert Rear Wheel HP to Flywheel HP= +50 HP


These runs were on a Dynaflow Dyno which reads low, to convert to what a Dynojet would read, you must multiply the result by 1.22, so in this case 299.4 on the dynaflow * 1.22 = 365 RWHP on a DynoJet

 

I think the next mod I need is the larger MAF. Ive got an intake tube, getting my TB bored (stock is 78mm), I have the smaller pulley and the later model eaton, so we will see.

 

After I installed the larger intake tube, TB, and ported elbow and intake manifolds, I noticed an improvement just by adding 1 additional 2" fresh air intake into the stock air box. This proved to me that the single stock snorkel to the fender was a restricting bottleneck. Also, the air in the fender is warmer than outside air as some of it is heated as it passes by the radiators in front. I noticed the delta in outside air and intake air got smaller when I added an additional inlet from outside air. The later 4.2 engine air boxes have an additional opening as the engineers saw the need for this upgrade. This is when I decided to go with the 92mm MAF. My TB is 82.5mm/3.25"

My existing set up is now:

3.62" 92mm MAF with open filter in cold air fed box sealed off from hot engine compartment air
3.5 Intake tube, a 4" would be better
3.25 equivilant Maxbored TB, ported elbow and inlet to SC

You have to remember to open the gasket's dimensions a little to match too.


I bought my larger MAF from Pro-M. It appears to be a very good unit, but be aware that you will need to source and wire a separate IAT sensor, as the PRO-M one is not correct for the Jags. I bought my sensor at the dealer part # LCC1602AA at Gaudin in Nevada for $74.

 

lol I said I wasn't going to mod this car like my other ones.....too late now!

 

WaterDragon, I noticed you replaced the upper s/c pulley. What are your thoughts on doing the lower pulley instead? From the threads here it appears to generate a gain of 50 HP in the mid-range.

 

I was just being cheap, trying for a low $/HP. I was on a quest to see how cheaply I could get a small/medium amount of power gain as a project.

The lower pulley will give more boost and quite a bit more mid range power. I'll be trying just the lower pulley and stock upper next.

Overall, performance wise, I think the lower is a better idea, but it does cost more, is a little harder to put on, and you will need to upgrade cooling a little more than the upper.

I only added approx 1.8 lbs, less than 1/2 the +4lbs the lower will give you.

3/13/14 Update- Having done just the upper and then just the lower, I say go just the +3 upper or +4 lower, after trying this, the power gain was incomparable!

 

so you got a cost of $22.00 for the 1st 50hp?

now how much is the dollar cost of the next 50hp?

 

The next 50?,

It depends if you want best bang for the buck up to 100 HP gain, if you are looking for how to most practically get something faster in the real world, as in on the road, down the track and across the intersection, then I would think if you are keeping the eaton supercharger, then adding these following would likely produce another 45-60 RWHP of usable real world mid range power:

lower +4 lbs boost pulley +35 to 50 mid range HP, but only +?or so on the top end, unless you have water/meth injection (which can lower IATs 50-70 degrees F) Approx $600 if you install it yourself
If you end up with 18/19 psi as I did, you will need to add fuel supply as the stock fuel delivery tops out at approx +20% or +74 hp.
I added a kenne bell boost a pump (approx $500) which, while on boost, runs the fuel pumps at 17.5v instead of 12 or 14v. This increases the fuel supply plenty for the +100 hp range. Some say running 10 gauge wires to the fuel pumps is enough. I don't know.

Soooo $675 for the first 50, then $350 for water injection, $600 for lower pulley, $500 for fuel supply, so approx another $2000 for the next 50, ends up being approx $2675 for + 100 hp. Search for my 0-100 in 10.5 seconds video to see that this has been done. This video was with a ported blower (which gave +1 more hp) Disregard the typed blather and watch the video, because "Seeing is believing"

If people want more than +100 hp, I think the best, most tried and true, dependable, and proven way would be to buy one of them twin screw kits, then they could safely have a dependable 100-200 hp advertised HP. If one wants to go the biggest HP gain, one must go with the much more efficient Kenne Bell.

If the peak HP and being as fast at every speed as possible is what is desired, and money is no object, then do go straight to the Twin Screw as everyone who has done so appears to be VERY happy with their purchases.

The fastest documented Eaton powered run I've seen was M. Moran at 12.4, and the fastest documented Twin Screw run so far is Steve M's 11.9, (a difference of .5 seconds)

So it comes down to what does one want from their cars. If money is no object, Kenne Bell wins hands down, but if one wants a 13.2 second +50 RWHP over stock X308 XJR/XKR for less than $900 in mods, it has already been done and proven on the track.

 

I agree with you on the price difference. Not too sure about the difficulty. Its a 2-3 hrs to install the lower pulley.

The upper pulley requires grinding down the s/c snout, cutting the old one off and heating the new one AND sliding it on perfectly, whew!

Didn't realize that changing the lower pulley requires cooling mods. Can you please give me a bit more info on what exactly those may be?

Thanks.

 

The +1.5 to +1.8 lb upper pulleys do NOT require any snout grinding, only the smallest +3 lb pulley does. If you get an upper, make sure it is grippy steel, not slippery aluminum.

As to the cooling mods, when I was running 18-19 psi of boost with stock upper and +4 lower pulley, when I had water injection running @ 375ml/minute, and was running a 12" pusher fan in front of the inter cooler radiator, I had LESS heat soak than when stock.

 

Where are you located Water? I PM'ed you.

Thanks!

 

I am in the San Francisco Bay area in California.

Since posting this thread, that blue 2002 XJR threw a rod (a bad result from a hydro locK caused by a leaking injector) and I got rid of it.

I now have a different black 2000 XJR running 18-19 psi and approx 470 HP

I responded to your PM

Update:
After trying small +1.7 lb upper only, then lower only, the 3 lb upper or lower +4 is the way to go. After having opened up my intake diameters, and injecting water/meth BEFORE the blower, the car can really use the extra boost. Adding a 12" pusher fan $29.99 from siliconintakes.com made a huge difference in controlling heat. The water injection's ability to control IATs is HUGE! Just adding upper and lower pulleys without a larger intake, tb, etc, does not work well and is just asking for overheating/detonation problems.

 

I wanted to thank you first of all for your posts... I found them very informative and fun.. I have been wanting to tweek my 96 xjr my way and I love the way you tweeked your stuff.. I am just wondering if you could give me advice on what parts to buy for an xjr6 i have bored out my tb and all new intake hoses I plan to fit the m112 in somehow.. In your case i believe someone changed the programing on your ecm. My ecm was reprogrammed also and it won't pass my emissions so i had to buy a second...they programmed it to run way to rich.. Just wondering if you would recomend and parts or what you would do to an xjr6 thank you

 

Welcome to the forum artistwithen,

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some info about yourself and your vehicle for all members to see.

In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

1996 xjr black saint louis ,mo.....I wanted to thank you first of all for your posts... I found them very informative and fun.. I have been wanting to tweek my 96 xjr my way and I love the way you tweeked your stuff.. I am just wondering if you could give me advice on what parts to buy for an xjr6 i have bored out my tb and all new intake hoses I plan to fit the m112 in somehow.. In your case i believe someone changed the programing on your ecm. My ecm was reprogrammed also and it won't pass my emissions so i had to buy a second...they programmed it to run way to rich.. Just wondering if you would recomend and parts or what you would do to an xjr6 thank you

 

Unfortunately I am completely unfamiliar with the x300s. I am happy to try.

I would venture to guess that the same things would be helpful though. Having new intake hoses and bored TB was a good move.

What size intake hoses are you going from and to?

Then a pulley upgrade is the way to go.

I had realllllly good results keeping temps down with adding water/meth injection and a $30 12" pusher fan, also from siliconintakes.com in front of my inter cooler radiator. If you don't want to spend the $300 on the water injection, definitely do the $30 fan, it makes a BIG difference.

Any idea on how much you want to spend? I'm a huge fan of just doing the stuff that brings the best hp per $.

If your ecu is programed rich, the 2nd one I'm talking about now, just add lots more air via less restrictive intake and higher boost (along with extra cooling), then see what your AFR reads, then we can go from there. The stock "tune" is on the safer richer side.

I have zero experience in swapping superchargers that do not bolt right up, here is where someone like Avos proves to have a much more superior capability to help you than me, but for the basic stuff, I am more than happy to help

You might also get more experieced responses posting in the x300 forum.

Jeff