Performance Improvement

[ckrause333]

I purchased an 07 XLR a few months ago and have found it to be a great car overall. It has one shortcoming, in my opinion: performance/power. I now realize I should have selected a V. At the time I purchased, I was able to find a car with 11K miles and was pretty infatuated with that. Has anyone been able to find performance enhancing changes that can be made to the XLR Northstar engine. I have read that tuning, via the engine control module, is doable. However, I can't find much in the way of pro's that seem to understand what to do.

Thanks
ckrause333

 

[ccclarke]

It is what it is. For a little more money, you could get a lot more horsepower with a V. The N* is very low on the mod list. You can add a CAI and a performance exhaust system, but the HP yield won't be appreciable.


CCC

 

[dennis93coupe]

Contact D3 in Signal Hill, CA for information on your XLR performance modifications. I have been told they can tune the 2007 and up base XLR. Good luck!

 

[lextoy]

i spent alot of time a few months ago researching performance options for the XLR. mine is also an 07.
for the 07, it is tunable by any reputable shop with some experience with hp tuners ,
some places have experience with cadillacs and northstars, but most will have never actually laid hands on an XLR.
tuning though is an art and a science, so a good tuner should be able to setup an xlr properly.
for the XLR northstar performance mods, theres not much...
volant cold air intake 300/ 100 labor
corsa exhaust 1600 / 200 labor
160* Tstat 20/ 50 labor
bore the TB 100/ 100 labor

then theres some seat of the pants mods that make it "feel" alot faster or tighter
add the rear sway bar 175 / 100 labor
add the C6 stiffer tunnel plate 150 / 100 labor
drop the rear diff to swap in a 3.42 gear, from the 2.73 stock gear(expensive mod) 2000 / 600 labor
(XLR setup is very close to a C6 setup so any good trans /diff builder will know what to do, i found several thru the vette forums)

tune the trans and engine for optimal performance 1000

doing all these mods at once would reduce the labor cost, because in order to do some, the same parts need to be removed anyway.
my estimates are based on some price quotes i got, and what i found online. could be +/- depending

after its all done, you need to get a tuner to update the trans computers for the 3.42 gear and tighten up/ adjust the shifts etc
and tune the engine for optimal performance.
based on my research a base 320 hp xlr is about 255 rwhp after the mods it will be about 285 rwhp

also might as well have the trans and coolant flushed so you know you are working with good fluids (150 +150)
and make sure you have good sticky high performance tires so it hooks up nicely.

from what i have researched this will make a big difference in performance, though not amazingly faster.
the 3.42 will launch way better, and minimally effect mileage and rpms, highway speeds are currently 1600-1800rpm
our 6 spd trannys are geared ideally for the 3.42... thus after the swap its only going to be 2000- 2250 rpm, not bad at all.
yes mileage will be reduced, but not too bad as long as its not all highway miles.

the only problem with all this is that by the time you are done, its still not close to a base corvette or an XLRV
and for the money you can step up into either one and go way faster for cheaper.

i am not doing mine for now, as it is running fine, and isnt that annoyingly slow. i also feel like the demographic for this car will actually dislike any performance mods and it will hurt value. stock is preferable for the dreamcar collector and retiree set
i tromp on it a bit harder to make myself feel better about saving 6-7 grand

if i get the itch i'll probably upgrade to a gallardo in a few years, that was my other dreamcar, or a CL63.
for now having a purple hardtop convertible is way cooler.

 

[ckrause333]

Very Informative. Thanks

i spent alot of time a few months ago researching performance options for the XLR. mine is also an 07.
for the 07, it is tunable by any reputable shop with some experience with hp tuners ,
some places have experience with cadillacs and northstars, but most will have never actually laid hands on an XLR.
tuning though is an art and a science, so a good tuner should be able to setup an xlr properly.
for the XLR northstar performance mods, theres not much...
volant cold air intake 300/ 100 labor
corsa exhaust 1600 / 200 labor
160* Tstat 20/ 50 labor
bore the TB 100/ 100 labor

then theres some seat of the pants mods that make it "feel" alot faster or tighter
add the rear sway bar 175 / 100 labor
add the C6 stiffer tunnel plate 150 / 100 labor
drop the rear diff to swap in a 3.42 gear, from the 2.73 stock gear(expensive mod) 2000 / 600 labor
(XLR setup is very close to a C6 setup so any good trans /diff builder will know what to do, i found several thru the vette forums)

tune the trans and engine for optimal performance 1000

doing all these mods at once would reduce the labor cost, because in order to do some, the same parts need to be removed anyway.
my estimates are based on some price quotes i got, and what i found online. could be +/- depending

after its all done, you need to get a tuner to update the trans computers for the 3.42 gear and tighten up/ adjust the shifts etc
and tune the engine for optimal performance.
based on my research a base 320 hp xlr is about 255 rwhp after the mods it will be about 285 rwhp

also might as well have the trans and coolant flushed so you know you are working with good fluids (150 +150)
and make sure you have good sticky high performance tires so it hooks up nicely.

from what i have researched this will make a big difference in performance, though not amazingly faster.
the 3.42 will launch way better, and minimally effect mileage and rpms, highway speeds are currently 1600-1800rpm
our 6 spd trannys are geared ideally for the 3.42... thus after the swap its only going to be 2000- 2250 rpm, not bad at all.
yes mileage will be reduced, but not too bad as long as its not all highway miles.

the only problem with all this is that by the time you are done, its still not close to a base corvette or an XLRV
and for the money you can step up into either one and go way faster for cheaper.

i am not doing mine for now, as it is running fine, and isnt that annoyingly slow. i also feel like the demographic for this car will actually dislike any performance mods and it will hurt value. stock is preferable for the dreamcar collector and retiree set
i tromp on it a bit harder to make myself feel better about saving 6-7 grand

if i get the itch i'll probably upgrade to a gallardo in a few years, that was my other dreamcar, or a CL63.
for now having a purple hardtop convertible is way cooler.

Very informative - Thanks

 

[PAK XLR8]

Did most of that...

Everything Lextoy wrote is pretty accurate, including the costs for each of the modifications to improve the performance. I know, because I did them on my 05 Base (gone now, but lives forever in my "Garage"). Check out my write-up on the 3:42 gear swap.

The only thing I would add is that while you can only squeeze about 10% more HP out of these 4.6L engines, the bang for the buck has to go to the 3:42 rear end and the exhaust. There will not be much in the way of HP increase (you will need to get the ECM and TCM tuned anyway), but with that extra low speed torque to the wheels, and the roar of the aftermarket exhaust, your car will certainly "feel" like it has a BIG performance improvement. These items (rear end, tune and axle back MBRP exhaust) put me back almost $3K. I did not enter to cost of replacing the rear tires more often in this equation