Super vs Turbocharging the car

[madfast]

its not just the "response" of the turbo. the power/tq comes on all at once. its not gradual and not very proportional to what your right foot is doing. yes you can compensate with driver skill and yes electronic throttles nowadays arent 100% proportional either, but still, NA and roots SC is best in those terms.

[dabocx]

Do both

Just going to be beyond expensive....

Ill be selling barbecue plates......

[DubyaTFudge]

I would go the SC route over a turbo. It wouldn't be as crisp as an NA motor, but you wouldn't have the lag of a turbo setup and the power delivery would be linear. Seems like a better fit for this type of car.

[serialk11r]

Could someone with a supercharged engine comment on the throttle response (by that I mean how "right" does it feel in terms of amount of power you're getting vs. how far you're stepping down on the pedal)? A problem I see is that bypass valve control inevitably gives you a bit of a "surge" at the end of the pedal travel. Obviously not as bad as a turbo where after a certain amount of load the turbo comes "alive" and the response becomes that of a laggy on/off switch.

When you install a supercharger, do you change the throttle pedal position sensor calibration so that you get full torque before the pedal is all the way down and then boost after, or is it set up to just boost when the pedal is all the way down? If it's just a kick of torque at the bottom of the pedal travel, does it bother you? Particularly looking for the experiences of people with lightly SCed engine like Ryephile and his Exige S

[NESW20]

Originally Posted by madfast

its not just the "response" of the turbo. the power/tq comes on all at once. its not gradual and not very proportional to what your right foot is doing. yes you can compensate with driver skill and yes electronic throttles nowadays arent 100% proportional either, but still, NA and roots SC is best in those terms.

Originally Posted by serialk11r

Could someone with a supercharged engine comment on the throttle response (by that I mean how "right" does it feel in terms of amount of power you're getting vs. how far you're stepping down on the pedal)? A problem I see is that bypass valve control inevitably gives you a bit of a "surge" at the end of the pedal travel. Obviously not as bad as a turbo where after a certain amount of load the turbo comes "alive" and the response becomes that of a laggy on/off switch.

where are you guys coming up with any of this? there's no way for me to ask this without sounding like a condescending ass (i'm not intending to be) but have either of you driven stock (or small frame) turbos at an autocross or track event? turbos aren't "on/off" switches. i invite anyone to come ride with me at an autocross and then tell me my turbo has crappy transient response and/or isn't linear.

FWIW, i will not add any kind of forced induction to my FRS/BRZ.

[madfast]

Originally Posted by NESW20

where are you guys coming up with any of this? there's no way for me to ask this without sounding like a condescending ass (i'm not intending to be) but have either of you driven stock (or small frame) turbos at an autocross or track event? turbos aren't "on/off" switches. i invite anyone to come ride with me at an autocross and then tell me my turbo has crappy transient response and/or isn't linear.

FWIW, i will not add any kind of forced induction to my FRS/BRZ.

a centrifugal compressor by definition is not liner. some people feel it and/or care, while others dont mind. we're all nitpicking here. so yeah it isnt that big a deal, but to some it may be, so we cant just sweep it under the rug. statements like "modern turbos have no lag" are just as dumb as "all turbos are laggy". the truth is somewhere in between and very personal to the driver's taste... the perfect example is the 335i vs 330i. the 335i is nowhere near "laggy" or lacking in response, yet the 330i is still more responsive albeit way slower.

my opinion is that for low boost a roots SC is the best option, then rotrex, then turbo. that's me. i like responsiveness

[AVOturboworld]

We added a turbo kit to a 2.5i Outback. The interesting point about it is that because of that, I have had the experience of driving it without the turbo kit, and with. And in a general sense, the original response is still there - it's just that when it's boosting, there's so much more power/torque that whenever you make the transition from original n/a (non)power to boostedomgwtfbbq power make the transition zone *feel* laggier than it actually is. If you are at the track and always in the boost, response is there.

The other advantage is that my overall gas mileage improved, since I don't need to fang it as hard to get it moving in traffic or on the freeway.

Regards,

Paul Hansen
www.avoturboworld.com
www.facebook.com/avoturboworld

[Dimman]

^ Um... the time between NA and boosted power is basically the common definition of lag.

[Randefelt]

I would like a S/C of some kind something that gives about +20-30 whp and retains the N/A feel. I am also wondering if its possible to run this engine on E85 and what that would do with a S/C.


I live in Sweden and the pries hear for 95 octane is about 8,77 USD/US gallon ( 16 SEK/Liter ) and hi octane is hard to come by and even more expensive. E85 is about 5,20 USD/US gallon ( 10 SEK/Liter ) so even with a 35% dropp in fuel economy i would save 0,37 USD every 6 mile (2,50 SEK every 10km) and the gas price is constantly rising but E85 is pretty stable in price this is all due to taxes.

[chulooz]

Originally Posted by madfast

a centrifugal compressor by definition is not liner. some people feel it and/or care, while others dont mind. we're all nitpicking here. so yeah it isnt that big a deal, but to some it may be, so we cant just sweep it under the rug. statements like "modern turbos have no lag" are just as dumb as "all turbos are laggy". the truth is somewhere in between and very personal to the driver's taste... the perfect example is the 335i vs 330i. the 335i is nowhere near "laggy" or lacking in response, yet the 330i is still more responsive albeit way slower.

my opinion is that for low boost a roots SC is the best option, then rotrex, then turbo. that's me. i like responsiveness

What cars have you felt this in, stock or modified? This is always the first question I ask when people dislike turbo lag..

It would be like disliking 4 bangers because they are gutless after not experiencing a good lineup of motors; but if you drove a good variation of a strong 4 your perception would be changed.

[madfast]

Originally Posted by chulooz

What cars have you felt this in, stock or modified? This is always the first question I ask when people dislike turbo lag..

It would be like disliking 4 bangers because they are gutless after not experiencing a good lineup of motors; but if you drove a good variation of a strong 4 your perception would be changed.

my daily driver is an evo x. its not very laggy but there is still lag. every turbo car i've ever driven both stock and modified had some lag. i notice it because i look for it. its not that big of a deal overall, but its still something i wouldnt miss if it were gone. again, turbo lag didnt prevent me from buying a turbo car, but i also dont act as if there is no lag at all.

[NESW20]

Originally Posted by madfast

a centrifugal compressor by definition is not liner. some people feel it and/or care, while others dont mind. we're all nitpicking here. so yeah it isnt that big a deal, but to some it may be, so we cant just sweep it under the rug. statements like "modern turbos have no lag" are just as dumb as "all turbos are laggy". the truth is somewhere in between and very personal to the driver's taste... the perfect example is the 335i vs 330i. the 335i is nowhere near "laggy" or lacking in response, yet the 330i is still more responsive albeit way slower.

my opinion is that for low boost a roots SC is the best option, then rotrex, then turbo. that's me. i like responsiveness

Originally Posted by madfast

my daily driver is an evo x. its not very laggy but there is still lag. every turbo car i've ever driven both stock and modified had some lag. i notice it because i look for it. its not that big of a deal overall, but its still something i wouldnt miss if it were gone. again, turbo lag didnt prevent me from buying a turbo car, but i also dont act as if there is no lag at all.

i believe we can agree to disagree. i guess what it comes down to for me is that the FA20 isn't going to lose any of its stock torque response with a turbo, and because it's such high compression, it won't rely so much upon the boost to create torque. it's just going to make more of it with the boost.

i'm honestly not familiar enough with the 335i and 330i engines to comment very much on that, but how much difference in compression ratios is there between the two? that, in my mind, plays a HUGE part in responsiveness to throttle inputs. my high compression 3SGTE with the same cams, same turbo, same throttle body, similar intercooler and nearly identical exhaust is unbelievably more responsive than my good friend's low compression (by design, not because of wear) 3SGTE. in his car, you wait for the boost to come on before you get much torque/response. in mine, you don't have to. it drives extremely well in vacuum.

i still notice the lag, however small it is with my setup, in day to day traffic situations. during sporty driving, though, my revs are up and i'm rolling into the throttle coming out of corners, so it's basically a non-issue.

[JohnnyR]

Without getting into internals work and raising to get more boost into the car, if one kept it at it's high comp levels, mid-single digit PSI would make a lot of power, the amount the car could definitely use. At these levels, a small turbo would be more than enough, and of course, it would spool up near instantly and have enough efficiency to carry good HP numbers into the top-end for what this car needs.

[eikond]

Originally Posted by JohnnyR

Without getting into internals work and raising to get more boost into the car, if one kept it at it's high comp levels, mid-single digit PSI would make a lot of power, the amount the car could definitely use. At these levels, a small turbo would be more than enough, and of course, it would spool up near instantly and have enough efficiency to carry good HP numbers into the top-end for what this car needs.

Even at 5 or 6 PSI, I'm still a little concerned that the compression is too high and it may not be safe.. Are the knock sensors good enough to prevent problems?

What impact does the direct injection have on all of this?

A bump from 200 at the crank to 250 or 275 at the crank sure would be nice! It doesn't have to cost $5k to do it either. I bet a decent kit could be put together for $2k or less.

I doubt that an intercooler would be required either.. sure it would help, but you wouldn't need a massive front mount like people run on their Supra's and other aftermarket kits.

Does the BRZ/FRS use a MAF sensor or MAP? If MAF, you'd have to recirc the blowoff valve.. .though at only 5 or 6 psi it might not be a huge deal anyway.

How about tuning? Would you use something simple like SAFC to fool the system or actually get a full tuned ECU chip or something.. that would expensive!!