I want to rebuild cars from leaderboards (f.e. Mazda RX-7 ´97 / B-Class)), so I load a leaderboard tune, then set the build again to default and now I can see what parts are changed because of the symbol which parts I own. Often the engine is changed and a supercharger is added. When I try to do this, I can change the engine but when I want to add the supercharger it simply does nothing when I press the A-Botton. The symbol is there that I own it, but it won´t add it. I got the same issue with a Golf before.
Does anybody know whats wrong ?

Its a glitch thats been around for years… easy work around… by the car first and purchase the engine swap and the correct supercharger then download the tune.

I recommend trying to build the car first before u start tearing apart other people’s hard work but that’s my opinion


Agree with this highly.


thanks for your replie,
I don´t want to tear apart others people hard work, i just can´t get near to some times at the leaderbord and I´m interested what the good guys are doing. because I know the build is 70% and the tune at most 30%. my driving skills I can gauge at the hopper where everybody must take the same stock car and I´m not that far away like for example B-Class /Road America (that´s the reason why I want to rebuild the Mazda) . The usual case is that I build the cars on my own…

Sort of unrelated but the supercharger on the V12 Zagato is bugged. It does nothing apart from add weight and drop the PI…

…maybe my bad english leads to misunderstanding. all I want to do is to learn building my own builds by looking what good drivers do and try out different things. and something don´t worked.
that´s what I´ve asked for. And now I got the answer, it´s a glitch…

yeah agree buy the car then do your own upgrades and tune there maybe a better or more efficent tune that would better the leaders times


These threads are what I love about the forza community… You see something you don’t like and fixate on it instead of providing the answer they’re looking for.

Why can’t I select the supercharger conversion after stripping someone else’s tune? 1 user gives the answer the rest answer with “build your own cars, don’t rip others off.”

If anyone wants my help message me on live, I’m about finished with the “community” here.


I applaud you for this post! SO TRUE!!

Indeed. Why jump down someone’s throat over something so innocuous and commonplace. People - tuners included - have been reverse engineering builds for years.

I am not going to sit here and lie to people. I have done it, and i think many of the best tuners have done it. When I am doing it, its usually from some of the top drivers/tuners or top drivers backed by known good tuners. I do it because theres a part of the tune I personally dont like, or think could do a certain section better so instead of wasting my time to eventually come to pretty much the same conclusion with the build that they have, just use their build. Then i tune it to my likings.

Sadly, any people don’t list conversions in the tune description.

To avoid glitches and issue that should have been fixed years ago, it’s always best to go into the upgrade shop and buy every engine and every aspiration conversion you think may be used on the tunes you plan to get. Check the tune, and see how much horsepower or torque it has - then go look at the engines and upgrades and start purchasing.

If you do not buy the parts ahead of time, they will glitch out as you have experienced and you will need to buy another car and do the above mentioned steps anyway.

It’s a shame displacement stats have been removed because they helped with the engine swaps portion…


P.S. I’ve also reversed a tune from someone here and there.

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If people actually bothered to reads the guys original post and replys properly, he does say that he usually builds the cars himself but wanted to see what the top guys were doing. Dont act like none of you have ever done it because im sure you have so get off your high horses.

Who cares about taking the build from a car, you still dont get the tune and one of the most important part is YOUR DRIVING SKILLS…if you dont do it then thats ok and if you do then thats ok too…get off this dudes case!!

I personally reverse engineer builds when I am stumped. I have hesitated doing it but I can vividly remember spending a full month on a build that I could not figure out why their car weighed a lot less than mine.
After weeks of frustration and hand wringing about the ethics of it idecided to reverse engineer the build. It showed massively different front to rear tyre widths.
I’ve always previously matched them up.

I don’t reverse engineer just for the hell of it. Some of us do it when necessary to learn and get better for our own builds.

Am I reading the same thread? The OP already got the answer needed in the first response. The poster also makes a recommendation to do before reverse engineering.

So… To highly agree with part of the answer given means “build your own tunes don’t rip others off”.?

Perhaps people assuming they know what someone is thinking is part of the problem…

I say this because your reply states “… the rest…”. My answer is above your statement, there are three replies besides the one giving the answer and recommendation. Mine being one.

No where did I say don’t rip off others. Did I expound in my comment. No. My statement was made because my opinion is that the poster could learn the most by tinkering with various combinations first which he was already doing so I felt no need to explain my comment.

I still recommend trying on your own before trying to reverse engineer.

Please be a bit more specific if you are going to call out someone’s comment.

And I will explain why I agree with a comment or part of a comment henceforth.

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Great job working “henceforth” in there, Crucian, lol!

“…we must have waffles! We must waffles forthwith!!”
Tom Hanks, Ladykillers

Anyway… I for one could care less about someone reverse engineering my cars. I’m pretty sure that what 90% or more of the people that download my drag tunes do. I have pretty close to 100 or more shared, all that I spent a good amount time working on. As much as some people may then there’s not much to drag tuning, there is alot more than you think when it’s not AWD Stradales and the like that ruined drag in FH2.

As far as i am concerned, if they downloaded my tune, i get that credit. Then most likely they at least test drive it or try a private lobby street race (seems to be the most popular way to race), maybe download one of my paints, credits there, (not from the test drive). If the tear it apart, oh well. If they learn how to tune and start really enjoying drag, or drift or whatever because of it then great!

At one point or another, in one iteration of Forza of another, we have all taken apart someone’s tune. I 100% agree with Crucian that the more you keep trying your own combos and builds and stuff, thats when I started really getting comfortable with my tunes. I still have a long way to go.

Bottom line, it’s a game. Enjoy it how you’re gonna enjoy it. And that supercharger glitch thing is just another on the long list of little things that should but most likely will never get fixed.

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Surely anybody who shares a build understands how trivially easy it is to disect it and know what major pieces got added to it. You don’t even need to strip the parts to identify engine swaps or forced induction additions; sound is the obvious giveaway, as well as the listed weight balance. Just check the telemetry and it’ll tell you how much boost it’s pushing.

I ripoff tunes all the time.

The concept behind the tune is what matters. The main variables that ever really matter are engine swaps, how much tire compound you give, and aspiration. The parts are 90% of the tune and the other 10% is tweaking in telemetry so long as you aren’t a donk. So long as you aren’t giving the car detrimentally wrong settings, its mostly just about making it drive nice. Which is usually the same motif of settings anyway, just a couple differences between the way different car frames handle.

Really the aerodynamics play a much larger role now in A class. That didn’t used to be the case.