-=Hot|Ice=-
High-Rev Hero
Scion FR-S Dyno
Scion Scion FR-S Dyno
- Thread starter -=Hot|Ice=-
- Start date
Scion was a youth-oriented division of Toyota that debuted in 2003 and was available only in the United States and Canada. It produced smaller, sporty coupes and hatchbacks. Toyota discontinued the Scion brand in 2016, and many Scion models were rebranded as Toyotas or discontinued.
Giannis
Staff member
Martin had once mentioned this midrange torque dip, but I am very curious to read his opinion on this. I wonder why does it happen...
speed_kills
Diesel Dynamiker
Does it have Toyota's Variable valve lift control?
Yes, Toyota developed it a long time ago (found in the Lotus Elise engine). Lexus utilizes simple dual VVT-i and 10 ITBs in the Lexus LFA engine to achieve a completely flat torque curve with 90% atleast being available from 3700 - 9500 rpm.
Unfortunately, this is not a Toyota engine, but a Subaru engine so they did whatever they wanted.
The Toyota 4U-GSE engine uses high rpm cams, what did that low rpm torque was very low and thus unacceptable for daily driving, what would make it another K20 (Honda S2000). To "fix" this, Toyota must have compromised the top end by tuning the intake for low rpm. This gives us torque with two peaks, one at 2.5-3.5K rpm for normal city driving, and one at 4.5-6.5K rpm for spirited driving.
The torque dip will be felt, but knowing it is there you could drive in such a way that you never pass by it. The good thing is that there is no real drop in power. This dip cannot be fixed completely, with new intake, headers, exahsut and ECU it can be improved but not completely removed. To be completely removed it would need a 3 stage variable intake like in the 1LR-GUE. The intake puts the peak torque close to the maximum possible at all rpm, it drops consistently as the rpms go down. You see it is close to peak torque at 4-9K rpm.
For me this dip is not a problem, as if I get this car, it will be as a track car, and what I'll need will be power and torque at high rpm. Planned mods are ECU, intake, headers, exhaust, cams, valve springs, control unit and pulley, which means lifted redline so +220 WHP, 230 Nm with sacraficed low-end torque.
The torque dip will be felt, but knowing it is there you could drive in such a way that you never pass by it. The good thing is that there is no real drop in power. This dip cannot be fixed completely, with new intake, headers, exahsut and ECU it can be improved but not completely removed. To be completely removed it would need a 3 stage variable intake like in the 1LR-GUE. The intake puts the peak torque close to the maximum possible at all rpm, it drops consistently as the rpms go down. You see it is close to peak torque at 4-9K rpm.
For me this dip is not a problem, as if I get this car, it will be as a track car, and what I'll need will be power and torque at high rpm. Planned mods are ECU, intake, headers, exhaust, cams, valve springs, control unit and pulley, which means lifted redline so +220 WHP, 230 Nm with sacraficed low-end torque.
I might be wrong, but I thought Toyota only developed the D-4S for the FR-S/BRZ while Scooby did the tuning and development??
Anyway, it is quite astonishing to see on that exact same dyno, LFA puts down 344 wheel HP more than the BRZ/FR-S (though, on a different day). That is over 400 HP difference at the crank, but that could very well be because LFA power/torque is underrated from factory (LFA put down 451 wheel HP on the Forged performance "heart breaker" dyno same day when a Subaru WRX STi put down 195 wheel HP).
Anyway, it is quite astonishing to see on that exact same dyno, LFA puts down 344 wheel HP more than the BRZ/FR-S (though, on a different day). That is over 400 HP difference at the crank, but that could very well be because LFA power/torque is underrated from factory (LFA put down 451 wheel HP on the Forged performance "heart breaker" dyno same day when a Subaru WRX STi put down 195 wheel HP).
speed_kills
Diesel Dynamiker
Levi, if it's a track car you want, get an Elise 1.8 190hp. Much lighter.
I want FR layout, and the BRZ is still cheaper, there might also be BRZ competitions, just like the are MX-5 competitions.
speed_kills
Diesel Dynamiker
I see you like FR layout. I think the BRZ will not disappoint you. I was just mentioning alternatives.
Centurion
Apex Apex Predator
It's because the engine has a large valve overlap i.e the period where the the exhaust valve close while the intake valve opens. It's a common profile for high revving engines and it does come with limitations such as low end torque, something which Toyota have managed to keep at minimum as there is plenty of torque 2,500-3,200rpm for driving at crawl speeds. Obviously variable valve timing would possibly have eliminated the dip. However the objective of the car is to be affordable and thus Subaru have done away with any expensive extras that would have resulted in a higher asking price.
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