How many lost horses

[Zippyworld]

So here’s a question, my X308 XJR is listed as coming out of the factory circa 370 bhp.

I had an upper pulley upgrade completed a few years ago and in the very near future will be upgrading the lower crank pulley, The crank pulley replacement is due to the existing being potentially faulty, so I may as well upgrade it.

Today, I did a Dyno power run and the car produced 343 bhp.Torques are still as per original spec. I will do a rerun after the crank pulley upgrade.

My question is what can I do to try and get some of those original horses back ? I dont want to spend any more on upgrades, maybe just replacement standard parts, or will a major service be productive ?

Any thoughts please ?

[Zippyworld]

I am still not happy.....

If I have a well serviced car and an upper pulley upgrade surely I shouldn’t be so far down on power ?

If the upper pulley gives, say, 30 bhp and I am getting 343, that is nearly 60 bhp missing somewhere.

Thats a fair amount to lose despite the cars age....where do Ineed to start looking for them ?

[Zippyworld]

This meadurement is at the flywheel. I am getting 278 bhp at the rear wheels

[Zippyworld]

The car is going for a crankshaft pulley upgrade, that should give 60bhp ish.
The cooling system is also being upgraded to cope.

Once its done I’ll get it on the dyno and report back next month.

Thankyou for the input so far....

[Zippyworld]

Fair point indeed. I will get it looked at soon, I had thought about it already.
Just decided do it the other way round because the lower pulley was alwaygonna happen.

[Zippyworld]

Just got the latest dyno reading and with a bit of magic we are at 410 bhp.