Now that my new XKR-S spoiler has been delivered and is scheduled for installation it's time to decide what my next modification will be.

I am trying to determine whether I will get more bang from a Paramount-Performance ECU remap or a set of Nameless Performance high-flow sports catalytic converters. I plan on ultimately doing both but I can't make up my mind which one to do first.

I already have a high-flow cold air intake(conical filter) and the Mina Gallery sports exhaust installed.

Any suggestions?

 

Which engine do you have?

 

I hav a 2007 XK naturally aspirated .

 

I think the gains mentioned with the ECU tune might be more optimistic than what you can get in reality. But it isn't that expensive, and there isn't that much you can do on a NA engine.

The sports catalysts will probably give you also some top end power, but I am not sure what it does in mid range on a NA engine (an SC has already plenty, so I never looked into that there). But still, I realy like them, they give more exhaust noise with the stock exhaust I use.

So why not do both.

 

For NA the only options ... are Sport Cats + Induction + ECU mod + Cams....
If anyone has any other ideas .. I am opened to offers...

 

You should do the exhaust changes first. The different flow through the exhaust will change the remap.

 

I hav already installed a true cold air intake(K&N) and a Mina Gallery exhaust system. I picked up approx 20bhp from these two mods. I plan on doing bothe the ECU re-map and the sports CATS but will prob do the ECU re-map w/in the nxt few weeks.

Other mods that I have made are mesh grills, powder coated calipers, aluminum pedals, iPod connectivity, removal of power antenna, XKR-S spoiler and Mina Gallery lowering springs.

@xksofia-What is involved with upgrading cams?

 

The cams job is more like a head upgrade you take the oem cams and put in fast road or racing cams. When you do that you must allways have a custam ecu flash..... becouse by changing cams you alter the fueling / air mixture and allso the gas escape. Has anyone done "porting" on their heads?

 

Here are some things I would recommend if you do H/C from my experience:

1. Make sure to find a reputable shop who does ported heads not only for reliability but also maximize the performance. Porting also leads to higher compression ratio and you don't want to have too high of a compression. I remember my C5 Stage II H/C had a compression of 11:1 and I had to lower it once I bought the ATI Supercharger by using a thicker head gasket.

2. Make sure to find a reputable shop who does installs of H/C because once you open up the engine (IMO), the possibility of more problems down the road.

3. The more aggressive cam you put in, the more lumpy the idle will be as it won't be as smooth as stock. If that does bother you, possibly consider a milder cam.

4. The more aggressive cam the higher the possibilty it might not pass emissions. There are tricks though such as changing the timing and remapping the air/fuel mixture to pass. When I had stage II heads and cam on my C5.......I went with a mild cam to make sure it would pass. The first time it didn't pass right after the H/C was installed but after the Corvette shop tweeked timing and the air/fuel regulator...it passed the second time.

5. Also make sure the bottom end (engine block) can take the additional power. These days cars are overengineered (ie. the 997TT can take up to 1,000 HP) and should handle a certain amount of additional power but I would make sure it can from an expert mechanic. When I had stage II H/C and wanted to add the ATI Supercharger, the Vette shop tested my bottom end and found it wasn't strong enough so I sold the car and never installed the SC.


Heads and Cam is where the real HP comes and H/C + install + tune cost around $4,000-$4,500. With that money + Possible less reliability after opening up the engine + lumpier idle (if that bothers you), you might want to consider as another option upgrading to a XKR with 120 more HP and with all the internals as stock. I would guess you would get around 100HP-120HP to the flywheel with H/C depending on which Heads and how aggresive your Cam is. Just a thought.....

This is when my C5 had the new ported heads and cam installed:



This was when it was all finished:

 

I have searched a couple of years back to someone that could modify cams, but wasn't successful. No one wanted to work on this due to the amount engineering time and the small market.

You could look at the AMV8 4.3 engine as an example to what could be possible having still a drivable car. They squeeze out 380 bhp out of the 4.3 engine (which is relatively similar to the Jaguar V8, and would be about 371 taking out .1 liter). That means they have found about 71 bhp, but AM claims it was with a lot of changes. I guess their headers have helped a lot, and probably also the camshafts and engine management. The AMV8 has an 15 MPG whereas the jaguar is about 19 MPG, so also shows what you give up when want to squeeze out more.
You could try to find AMV8 camshafts, they may fit, but that needs to be examined.
I would also be interested in different cams, but as I have a SC engine, can’t use any naturally aspirated camshafts.

@ghostriderxkr08,
Do you know a place that has the capabilities to make/rework camshafts and wants to do this without costing an arm and a leg?

 

Moe-she -sa,
The mina exhaust is a beautiful piece of work.
Are you happy with it?
Do you feel the power increase that they claim?
Can you describe the sound difference from the stock exhaust?

Thanks

 

The Mina exhaust is sounds lovely. It has a nice baritone grumble. It sounds much better than any of the OEM systems (new, old, S/C, N/A, 4.2 litre or 5.0 litre) I believe it to be true and it has been confirmed by numerous techs and mgmt at both of my dealers and my independent. As for performance, I think there is def an increase. I noticed most when accelerating at highway speeds. This was further enhanced when I added the cold-air intake. I will say that my dyno results showed me 310bhp or 315bhp at the wheels. However I did not do a baseline or before dyno.

 

Thanks for the feedback, I'm thinking of doing a Nameless hi-flo cats and the Mina exhaust.
You've peeked my interest again with the cold air intake. Is that Mina's as well? Did that affect engine noise at all?

Thanks again

 

I am going to do the Nameless High-flow Sports Cats over the nxt month or two. I designed my own Cold-Air Intake. It was soooo easy. It looks very similar to XKRacer's except I used a K&N Air filter, my silicon is black and I did not modify anything above the MAF sensor. There is slightly more engine noise. The increase was not to the same degree as the noise increase that I experienced when I added a K&N cone filter to my XJ8.

One more thing about the Mina Sports Exhaust, it does not crackle on over-run. Personally, I HATE the crackle but some people prefer it. In fact I have seen it marketed as a feature.

 

@Mike V- Also I used a 60 degree stainless steel mandrel bend where XKRacer used blue silicon.

 

Great info! Thank you again Moe-she-sa.

When I first heard the crackle I thought I broke something, now I've grown to like it but if I get the Mina I can live without it since the look of the tips and the overall sound will be an improvement.

 

Hi Moe

Tried to reach you via PM but, no luck. So, I'll try asking you here;

As I posted before I am unhappy with the sound resonances of my stock muffler. It drones ever so slightly at 70MPG cruising speeds. Not sure if something wrong with it or not, that is NOT the question.

I read your reports on the Mina exhaust and how you and everyone else likes the sound improvements over the stock. So, the one question that is most important to me is; how is it a cruising speeds? Can you hear ANY exhaust sounds/droning at a 70 MPH steady cruise?

Second question: Can you post your dyno results? I'd love to see the power and torque curves. I am entirely surprised that you would get 310-315 rear wheel HP. I'm sure that the stock engine's 300 HP was a fly-wheel rating. From that I'd deduct at least 10 - 15 percent for parasitical losses. That would place the rear wheel HP of the stock engine to no more than 270 HP. 40+ HP gain from the exhaust and the intake would be HUGE!!!

Or, did Jag under-rate the engine power in the '07+ 4.2 L? I definitely feel more power from this engine than from the same 4.2 L engine in my previous '05.

Albert

 

@axr6-It really depends on throttle position. I do a lot of highway traveling and don't have an issue with droning. The car is pretty quiet for the most part. It is especially quiet after switch to Kumho tires.

As for the dyno, I think I misspoke. The hp numbers I posted were taking into account loss of power through drivetrain. I have a printout of my dyno run that I would need to scan. I could not use the software the the shop gave me because it is PC based and I have a Mac.