Think about that the next time you consider turning up the boost, leaning out the AFR, or advancing the timing.

 

i just watched an old Roadkill where they turned up the boost and leaned out the Bonneville car, which blew it up, and that was a V8!

 

I don't get what people are doing with their cars who want a million horsepower. I drive my car on twisty backroads, and in that environment the car already feels overpowered for the street at ~290 hp. Lightweight exhaust and battery pays more dividends than more power, IMO. it's all about the driving feel. If you want to do highway pulls, get a Corvette or a Supra rather than turning an FD into something it's not.

 

I feel like there's a story here...

 

So you cant build a 500+ whp that can last?

290 hp may feel overpowered if there are no handling mods.
at the end of the day if you are happy with the 290hp that’s great, other people have other things in mind

What i dont get though is this thread, you might aswell call it “smoking kills” or some other vague meaningless empty statement of that nature.

 

If Peter wants a story, he shall have a story......

Built my old first love '93 VR R1 (The Red Baron some called her) up to ~500 rwhp from 1998 to 2012, culminating in this feature originally back in Modified Mag:

https://www.motortrend.com/features/...93-mazda-rx-7/

Two months after the feature was published, I totaled the car on a damp NJMP Lightning (turn 7 funny enough). Definitely a bad day, frame bent but the mods survived.

Bought a cherry '95 low mile (35k?) BB from an IRP customer that was fairly stock, a stock-spec engine we'd recently built and some bolt ons--- PFS intake & IC, DP and CB at like 13 psi. If I'd of known I was going to buy the car I'd definitely have recommended a different mod path during the work performed

I distinctly remember the moment I decided "Eff this, I need 500 rwhp not 300 rwhp." It was when some Dodge SRT8 sedan something pulled me on the NJ Turnpike from like 70 to 130 mph. PT6466 at 20 psi? Yes please, haven't looked back once since

 

I don't need anymore horses, I just want the horses I have not to escape the stable.

 

Well said. I know a few people who get paid to build cars or tune cars. Most of them won't touch rotary engines and they still leave power on the table for nearly every vehicle, because it's more important for most people to finish the race and have fun than to maximize the engine output for a few passes. If you are spending your own money on a modified car, you probably need to leave power on the table even if it's a race-only trailer queen. The teams who need every last bit of power have spare engines and engineers watching the data to avoid needing to use those spare engines too often.

Also, it's 2023 so please install a fuel pressure sensor and oil pressure sensor on your modified car, use the engine protection features in your ECU, and learn to review datalogs so you can see for yourself if things are running safe. Replacing an old ECU with a new one is cheaper than a new engine from Mazda, and probably has a quicker turnaround time also. HP Academy is a great resource if you want to learn about tuning, their free videos on Youtube are a great start and their paid courses are worth it.

 

I think in the age of easily accessible social media it is very easy to unintentionally have your perception and expectations of things skewed. If someone who is new to these cars does a search on the internet, youtube or any other medium of your choice, one of the first things you are going to see is a headline or title that says something of "eleventy-billion wheel horsepower rx-7 shoots 100 foot flames and can reverse the orbit of the earth". Those who may not be well versed may now believe that this is the "standard" so to speak and that you must go to such extremes.

Whilst I have not been at it as long as many of the folks here, I have noticed that a very common progression of ownership these days is someone buys an fd and only has exposure with the ones seen on social media and believes that they absolutely must have a 650 whp single conversion. They get a car and send it straight to a shop and because they haven't driven it much or have not at all, they end up falling into the trap of checking boxes to achieve a specific dyno number and forget that modified vehicles are best viewed as a system, and whilst there is nothing wrong with knowing what you want, you absolutely must consider everything that will go into that system and how they interact with each other, and how you can manipulate them to achieve a desired result. The issue here is that many tend to have no experience with the platform and thus usually do not have much of an understanding of how everything works. They'll have a car put together that makes their goal of 650 wheel, but because everything else was never considered, it isn't very good at anything other than highway pulls, roll racing and spinning tires. Such builds usually end up being sold shortly after an obscene amount of capital was put into it.

With that being said, I think your advice is sound. Knowing what you want and what you will need to get there, and considering of possible outcomes (breaking engines), you will be better prepared to deal with and mitigating risks.

 

Nothing wrong with making 500hp, as long as you have done everything to support 500hp. Problems arise when you get carried away. The endorphins when your car hits the dyno are real... that last, extra, 2 psi, above what you have built for..

 

Speaking of which. I have been loving how this car has been turning out. But I cringed watching this video and how they are tuning it. Maybe making it misfire and boost creep sounds worse than it is in person...

 

Just a general thought (inspired by the famous Gucci quote "Quality is remembered long after price is forgotten" which popped into my head) from me tuning and giving tuning advice over the years. There isn't one exact story, and it isn't even rotary specific. In this case there was a thread in the Haltech forum where someone was looking at some example timing maps I made in 2010 (!) as a sort of baseline/teaching tool for 2nd gen FC's on chipped Rtek ECUs. I explained (with the benefit of years of hindsight) that if you have the time and resources, you start out really conservative, and measure the gains from each more aggressive change. Then you make a decision on how much to push it based on power gain vs potential loss of safety margin.

Timing Map - RX7Club.com - Mazda RX7 Forum

Also, if you dig through stock fuel and timing maps on engines from the era (FD's don't run rich. - RX7Club.com - Mazda RX7 Forum) you see how conservative they are. And yeah they leave a lot on the table... but they generally don't blow up when stock, so there's that.

 

I’d put AI in the same category. Even losing some HP using straight water is better than the alternative.

despite break-in appearances etc it seems to me they’re doing their best to done-blowed-it up prematurely, wasn’t even tuned past 4500 yet and there they are getting all on it in the parking lot *after an unsuccessful tuning attempt*.

I also came to the opinion a long time ago that free-rev zinging a rotary engine is not good for long term durability, but there’s no shortage of people who can’t help themselves. Doing that untuned is certainly not wise.
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