I had a pulley and tune done by ETG last August. After awhile I felt the car didn't feel as aggressive. Maybe I was just getting used to the way it feels so I decided to get it dynoed. Three pulls were done and the second pull yielded the best results. It was 85 degrees today. Uncorrected was 475 hp and 441 torque and corrected was 493.6 hp and 460 torque. I attached the dyno sheets for your review. One is uncorrected and the other has a standard correction. This is rear wheel hp. Does anyone know what the power loss is through the drive train so I can calculate crankshaft HP? Stock was 510 HP so what is it now? I never had a dyno done before so I don't know what numbers are considered good for rear wheel power.

Dyno (2).pdf

 

THANK YOU! THANK YOU!

I have been begging people to do this to see if they even have the original HP before doing a tune. I wanted to know without being the guinea pig what the average guy losses.

You have a carbon buildup issue most likely. Its an impossibility that you dont have some carbon on the intake valves.

Thats why it amazes me that people do a tune and not an engine clean to at least get the HP that you are supposed to have.

 

This is also the reason that I find most tunes (not the one that Stuart does) scammy. Because they dont even measure the original before promising an improvement. That's like a doctor promising to improve someone's back without even doing an xray of before nor after.

Yes totally expected. Get rid of that tune, it may have contributed to carbon buildup. Clearly they did not know whats actually going on in the engine.

 

A lot of tunes come from database "warehouses" that "tuners" use and pay anywhere from $100-$300 each for. Some members here have gotten tunes from Eurocharged in Houston and posted before and after dyno charts that show gains from the tune, but there have also been issues with that company. Many Jaguar tuners I have spoken to were not able to answer all of my questions, which is why it has taken me 5 years to still not have a tune. I did dyno pulls when I did the pulley a few years ago and will do more before and after pulls with Stuart's tune, when ever we get around to that.

 

That certainly can contribute and so can bad plugs, filters, old cats, etc.

Carbon build up can be caused by a rich mixture which I would think is not the case as most tunes should be leaner, not richer.

 

To respond to your question regarding power loss through the drive train. multiply your reported HP by 1.2 to get to the crankshaft HP. Taking your two dyno runs at 475 and 493.6 your new HP is somewhere between 570 and 592. Keep in mind this is a rough figure. You can google the following phrase "BHP loss at drive wheels compared to BHP at crankshaft".

 

Ito determine hp at crankshaft the engine must be measured on a engine dyno.

It's impossible to convert rwhp to crank shaft power via a formula as there is way too variables including the dyno operator and actually dyno manufacturer

The sole purpose of the dyno is for it to be used as a tuning device only .

Once a baseline pre-tune output is made , you obviously carry out whatever performance work you desire ( in our case here it was a tune and pulley ) then put the vehicle back on the dyno and then you will see how much power was actually gained and where in the rpm range

 

Actually BHP, Brake Horse Power, is only used in reference to power at the flywheel and WHP, Wheel Horse Power, is used to measure power with a rolling road, dyno.

The 1.2 times WHP formula is widely claimed to estimate BHP, but as Steve mentioned here, is not always accurate nor are the numbers indicated by a dyno, without having a baseline established on the same dyno and same calibration.

 

I think you have that backwards. 1.2 X WHP = BHP.
The way you said it, you'd have 20% MORE WHP than the engine can produce.
Or the other way, 0.8 X BHP = WHP would be correct.

 

My slip , but since the dyno only measures WHP, it is 1.2 X dyno WHP = BHP.

 

The other way around. Leaner engine= hotter engine, equals carbon. That is why Jag is dumping extra fuel into engine.

 

You are right about a leaner mix being hotter but that does not create excessive carbon build up. Running too rich leads to unburned fuel which creates abnormal carbon build up, there will always be some carbon as the by product of combustion. Too much carbon and I would think you would notice the engine running rough. Checking your spark plugs will tell you what is going on.

 

Thank you for this advice. It started to sound like an exhaust leak getting slowly louder and rougher sounding but the dealer said there was no leak. It must be getting rougher from build up like you said. What do I need to do to clear this up? Do the plugs need to be changed? Could it also clog up the exhaust and cats? I have to say that after the tune it did feel quite powerful, aggressive and responsive but not so much now.

 

As I mentioned above, if you pull one of the plugs, it will tell you if you are too rich and fouling the plugs or too lean. No need to change the plugs until you do this and determine the cause and correct it first. Yes, the cats can get clogged with too much carbon, but you'd likely get a cats error first.

 

To clear this up: you can use a scope to see the intake valves- its the only way! Or you can just attempt to clean it anyway. Since you are into performance tweaking.

BG has an induction service that does clean somewhat. There are cautions about harming the car- but you are brave anyway because you went with a tune that also has the same warning- so I dont see a risk. I have heard about Hydrogen cleaning as a much more effective solution. But I dont know if it is available in usa or not. SERVICE "CARBON CLEANING" - HYDROGEN SOLUTIONS

The only way to clean it for real, and get additional performance even above the manufacturers specs is to have the intake polished, with walnut shell. You can also put a ceramic type coating on the metal to prevent future buildup. Many manufacturers would at one time put such coating on the throttle body, I dont know if they still do. While you are at it polish the supercharger- it will also yield performance gains.

 

ETG tune does not change the fuel ratio so they say. But the car is running rougher anyway. I'll have a plug checked and go from there.

 

What do they change?

The alternative is even worse.

 

I asked what they change but it was more like a list of what they dont change. I know the accelerator is made more sensitive so you need to use less pedal. He mentioned the car has a torque limiter. They may make changes to that. I guess what you mean by making it worse would be if they do changes to trick the ecu instead.

 

They most likely only change fuel ratio. Removing the limiters will not get you the extra power they claim. And you arent at present even able to reach the limit set.

If they change the timing they will affect the carbon buildup problem in a bad way. One of the ways that Jaguar mitigates the carbon problem is with timing.

 

Not intending to thread jack, but I'm headed in Friday to have the induction system cleaned (BG44), and like Q&C I wanted to know my starting point.
So here is the chart for my new to me XKR, and I'll do a follow-up shortly after the cleaning for comparison.
My XKR has 30Kmiles on it now, and no clue what to expect from the cleaning, but no harm no foul...

Vince