So I'm looking at the specs on the two cars and find they have the same Liter, Bore, Stroke and Compression....so I wonder how how they squeezed out an additional 40HP and 41TQ. I doubt just a different software tune would get that much on a SC car....maybe on a Turbo.

Could it be it's the same engine but Jag just rate the HP on the XKR lower than it should be? Reason is someone on the XFR section dynoed his stock XFR (same 5.0L as the XKR) at 460RWHP....that equates to 552HP to the flywheel with a standard 20% (for automatic trannys) drivetrain parasitic loss (not sure what the Jaguar drivetrain % loss is). That's the same as what Jag rates the HP on the XKR-S. I'm sure they did some additional engine tweaks on the XKR-S....if I owned a new XKR-S and raced a XKR and it was neck and neck....I would be POed!

Just curious what they did to bump the HP.......

Link on Specs: Jaguar USA - Jaguar Cars

 

My guess is boost is increased via a smaller diameter supercharger pulley, similar to what you've done with your '08. Can't verify for sure since Jag's pulleys are not a separately available part from the supercharger itself. That, and nothing for the XKR-S is in our parts catalog yet - but you'll be the first to know when I see it.

 

It is very easy to bump up the power on the newer 5.0 sc cars. For one the ECU is limiting the power levels to safeguard the transmission, so just taking out these limitations will already give extra horses (so without finetuning the fueling/ignition even). Then (contrary to the older 4.2 eaton blowers), you can easily spin the supercharger faster, so all in all getting 50 bhp more is childs play.

 

Ahh...thanks for the explanation Avos.....so the 5.0s are more tunable.

 

hahaha.............Dan's always on top of things