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Actually you show your limited experience.
Torque bends rods
That's exactly why I only want to raise and flatten the torque curve withOUT a peak torque increase. You got it! That gives my driving style 90 percent of the benefit with no risk of regular design eceedances, which as you point out bends rods or finds some other weak link in the overall design.
The way metal works is it is elastic below the engineered design limit and plastic above, so every exceedance cumulatively contributes to early material failure. No thank you.
It's a valid question. I think, but no one really knows, the 495 tune was likely conservative to limit risk for early model years. Based on some on ramp criteria, the go ahead was granted to plus up to 550. I would not consider the SVR part of the typical trade space since the owners were essentially asked to fund jag's risk mitigation plan with a truly crazy price tag. So my answer is 550 is suitable to exit the warranty period with little risk, and 495 will substantially extend service life. What's your guess?
I would think you would increase peak torque, assuming it occurs before the point where the SC starts dumping excess boost.
My optimum, though unachievable, tune would provide a dead flat 99% of stock peak torque curve across the entire rpm band. That way there is no design stress exceedance. Peak HP is irrelevant as it's simply a calculated function of torque after the stupid shaft horsepower assumption that rpm is the same as actually moving the cars mass across the Earth.
You wouldn't even need the stock 550 tune's 500 ft lbs, since the flat torque curve would rocket the car to 60 in some ungodly low time, assuming traction was achievable. And no, I don't care about random test points, so any 0-60 traction issues are arbitrary so mostly meaningless to me.
Maybe this simple video can help - he uses simple explanations and easy to understand props. Pretty sure it concludes that cars with higher HP will beat cars with high torque.....
How does the supercharger know which pulley is spinning it faster? And is anyone running either, or both, pulley(ies) only? Good option? Other supercharged cars have no need for a tune to change pulleys, is the jag tune requirement just up-selling?
Because the lower pulley will increase the boost to levels not anticipated by the mapping, throwing an”exceeding expected values” code. The increased boost from the upper pulley is not nearly as radical due to dimensional constraints. (the pulley diameter can only be reduced so much.)
Maybe this simple video can help - he uses simple explanations and easy to understand props. Pretty sure it concludes that cars with higher HP will beat cars with high torque.....
Utterly clueless video. HP is a simple mathematical function of torque when you make the erroneous assumption that all dynos make, that RPM is equivalent to the car's mass moved across the surface of the Earth.
Because the lower pulley will increase the boost to levels not anticipated by the mapping, throwing an”exceeding expected values” code. The increased boost from the upper pulley is not nearly as radical due to dimensional constraints. (the pulley diameter can only be reduced so much.)
I have a question. Does anyone here run a custom tune or has had vap change the tq output to be lower at lower speeds and increase it as speeds increase to maximize traction. On my turbo s2000 we tuned it for boost by speed which helped with traction at lower speeds and off the line, but once speed increased so did boost. I realize that this is a supercharged car and is not set up the same was as a turbo car, I know how they both work. I’m just wondering if there is a way to tune for this with the v8s. I mentioned this to Stuart in an email as I’m planning to try and push the limits of this car as my project gets going. Hoping he has some more input on the subject.
Unfortunately I don’t know of any tuners in my area that have experience with the Jaguar. Personally I would rather have the car tuned on a dyno, as I’ve done with all my other project cars, but for now i trust vaps tune untill I get outside the more common mods.
To op: I agree with others here it is safer to go with a tune than just slap on an upper pulley. Better bang for you buck and much safer. But If you do decide to just do an upper pulley let us know how it works by itself. I’m pretty sure your going to want more power once you get a small taste of it.
I have a question. Does anyone here run a custom tune or has had vap change the tq output to be lower at lower speeds and increase it as speeds increase to maximize traction. On my turbo s2000 we tuned it for boost by speed which helped with traction at lower speeds and off the line, but once speed increased so did boost. I realize that this is a supercharged car and is not set up the same was as a turbo car, I know how they both work. I’m just wondering if there is a way to tune for this with the v8s. I mentioned this to Stuart in an email as I’m planning to try and push the limits of this car as my project gets going. Hoping he has some more input on the subject.
Unfortunately I don’t know of any tuners in my area that have experience with the Jaguar. Personally I would rather have the car tuned on a dyno, as I’ve done with all my other project cars, but for now i trust vaps tune untill I get outside the more common mods.
To op: I agree with others here it is safer to go with a tune than just slap on an upper pulley. Better bang for you buck and much safer. But If you do decide to just do an upper pulley let us know how it works by itself. I’m pretty sure your going to want more power once you get a small taste of it.
I disagree that a tune is "safer" than a pulley change. That's like saying a tune which violates every design limit through trial and error is safer than driving from Albuquerque's pressure altitude to LA.
I would be more inclined to trust VAP if they had access to a legible dyno result and an open support board with users. It doesn't build confidence that they used to have a fake dyno up with a crisscross 1K off from 5250. By all industry standards, VAP is in alpha testing.
Everyone is entitled to their opinion. In any case any time you start altering things on a car, like a tune, or pulley, etc you are taking a risk. At least with a good tuner they tune with a certain range of safety in mind. Unless of course you are out to get every last hp out of the car you can, then those margins of safety are greatly reduced and the risk of failure is much higher.
Cars fail, tuned or untuned, you never can guarantee that this is not going to happen. Its the weak link that usually goes first. The more hp, the more stress. You probably understand this, but it’s a risk that we all take when modding. I would rather have a quality tune first and then upgrade from there.
It’s good that you have a direction, and know what you want from the car. If you can get a before and after dyno plot, with af, etc, when you install your pulley. I think we would all be interested in the results.
If you search you will see that there are quite a few dyno plots on here that have before and after results with a tune from vap. Keep in mind that the actual hp numbers are almost irrelevant, its the delta between the two different curves, before the tune and after the tune, that matter. I don’t think it’s fair to bash them as they are very knowledgeable with Jaguars, and many other high end cars. Their claims have been supported by real world results. And they have a long standing track record in terms of reliable tunes.
I wish you Good of luck with the car. I’m sure you are enjoying it just as much as the rest of us do.
Ok so let's review class: VAP is fake. And throttle pedal delay is real. Got it. /s
Yep they had a dyno compare with a crisscross at 4K. Replaced by illegible garbage. Throttle lag is real. That's why your VAP guys say they implement a far more aggressive throttle curve to get all the lag out.
Looks like a base dyno run tommorrow and the pulley should be here in a week or so. Don't worry, my before and after dyno will actually be real, legible and will crisscross at 5250.
I know it isn't the same car but my 5 litre 2010 XKR has the XKR-S tune plus the XKR-S X pipe on it. I got dyno runs done when both stock and after the applying the XKR-S tune and on Tuesday next week I will be getting another dyno run done because I had a smaller pulley put on the supercharger earlier this week.
You can see the results so far below and I will post the results from the new run if you want. Based on published figures for a stock XKR and the results from the two runs my car is putting out just over 550bhp now so it will be interesting to see what a difference the pulley makes.
I know it isn't the same car but my 5 litre 2010 XKR has the XKR-S tune plus the XKR-S X pipe on it. I got dyno runs done when both stock and after the applying the XKR-S tune and on Tuesday next week I will be getting another dyno run done because I had a smaller pulley put on the supercharger earlier this week.
You can see the results so far below and I will post the results from the new run if you want. Based on published figures for a stock XKR and the results from the two runs my car is putting out just over 550bhp now so it will be interesting to see what a difference the pulley makes.
Very impressive that, not only did you make gains everywhere, the curves on the tune are actually more linear and the torque is flatter and holds longer. That is a really good tune, may I ask who the tuner is please as they did a great job.
07-26-2018, 04:30 PM
