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    Tale of 2 Twin Turbo engines (and some others.....

    .....500hp units.


    Now that I have taken delivery of my 335xi, I have a chance to compare the 997TT and the 335xi's engines.

    Both have around the same displacement, both are twin turbo-ed with 3 cylinders feeding each unit. But while the Turbo gets up to 18psi of boost, the Bimmer only does around 8.5psi and hence the ~180hp difference.

    Both are awd with automatic but the Bimmer gets a 6 speed unit.

    Off the line, the 997TT just simply flies, even without brake torque, there is no lag whatsoever, it continues the lagless-ness all the way thru the gears. While in the Bimmer, there is a little bit of lag coming off the line but once in second gear, it just rockets onwards. I have to say apart from that the 2 engines have very similiar characteristics, but the Bimmer is around 7/10 of the Porsche.

    Since the 997TT is my car, I considered it a fair deal that my wife also gets a twin-turbo-ed awd car, but since she is the wife, she only gets 300hp but with a bigger backseats for the in-laws.

    While on the subject of engines, the AMG 55 is still my all time favorite, big displacement paired with a roots-type supercharger, instant power everywhere.

    The AMG 6.2 is my second favorite, seeing 6.2L worth of V8 revving to 7k rpm is just unreal. The Z06 unit comes really really close, it's almost a toss up.

    Best I would consider the Porsche 3.6TT unit is only 4th place, yes it has VTG and racing block heritage but imo the 2 AMG ones and the Z06 one is a little bit better. But it's still an amazing powerplant, matching the hp and torque output of much bigger sized engines.

    I would consider the F430 V8 and the V10 in M5 and Gallardo coming in after the Porsche unit bcause they make absolutely no torque down low and needs to rev alot to go anywhere. Almost feel like they have the turbo-lag in a non-turbo car. I think of them as gyroscopes, sure spins like crazy but they don't actually go anywhere.

    Re: Tale of 2 Twin Turbo engines (and some others.....

    Quote:
    Whoopsy said:Both have around the same displacement, both are twin turbo-ed with 3 cylinders feeding each unit. But while the Turbo gets up to 18psi of boost, the Bimmer only does around 8.5psi and hence the ~180hp difference.


    Not exactly - Porsche has 20% more displacement (335i has only 3.0L, despite name) and the BMW has MUCH higher compression ratio, due to the use of Direct Injection (so less boost needed for big power). To get 400hp from the 335i, you only need to add 2-3 psi more.

    See: www.vishnutuning.com

    Also, are both your cars automatic transmission? The greater lag you're feeling in the 335i could likely be due to the different (worse) automatic gearbox. 335i I drove had almost no lag at all (6 speed).

    Re: Tale of 2 Twin Turbo engines (and some others.

    autos usually have less lag in turbo cars. The torque converter allows for quicker spooling

    Re: Tale of 2 Twin Turbo engines (and some others.

    Quote:
    eclou said:
    autos usually have less lag in turbo cars. The torque converter allows for quicker spooling


    The automatic drivetrains on street cars are painfully laggy. The transmission is programmed to start in second gear and then put you in the highest gear to get the greatest fuel economy, which also puts you at the engine's torque minimum. When you hit the accelerator, the transmission must first shift you to a better gear and then build the engine's rpms before you get to the engine's sweet spot. Some cars will even struggle in the high gear for a few seconds before shifting down, which further increases the drivetrain lag.

    Does the 335xi let you choose a gear and keep it? If so, you should be able to eliminate the drivetrain lag in the 335xi by holding the car's transmission in a lower gear that keeps the engine's revs up above 3k.

    Re: Tale of 2 Twin Turbo engines (and some others.....

    I would consider the F430 V8 and the V10 in M5 and Gallardo coming in after the Porsche unit bcause they make absolutely no torque down low and needs to rev alot to go anywhere. Almost feel like they have the turbo-lag in a non-turbo car. I think of them as gyroscopes, sure spins like crazy but they don't actually go anywhere.

    Yea, they are slugs. Ferrari, BMW and Lambo should be ashamed of themselves for putting on the street such dogs.

    I find interesting that in the past few days TT owners are defending the car as much as they do. Subconsciously are they uncertain or disappointed in their purchase?

    Re: Tale of 2 Twin Turbo engines (and some others.....

    Quote:
    Grant said:
    Quote:
    Whoopsy said:To get 400hp from the 335i, you only need to add 2-3 psi more.

    See: www.vishnutuning.com



    A friend of mine just got this done to his 335i and absolutely loves it! I guess that's a good recommendation if any. I can give you his email address if you'd like to talk to him about it.

    Re: Tale of 2 Twin Turbo engines (and some others.

    Quote:
    hatchback said:
    The automatic drivetrains on street cars are painfully laggy. The transmission is programmed to put you in the highest gear to get the greatest fuel economy, which also puts you at the engine's torque minimum. When you hit the accelerator, the transmission must first shift you to a better gear and then build the engine's rpms before you get to the engine's sweet spot. Some cars will even struggle in the high gear for a few seconds before shifting down, which further increases the drivetrain lag.



    turbo lag is not the same as transmission hunting.

    Re: Tale of 2 Twin Turbo engines (and some others.....

    Quote:
    Grant said:
    Quote:
    Whoopsy said:Both have around the same displacement, both are twin turbo-ed with 3 cylinders feeding each unit. But while the Turbo gets up to 18psi of boost, the Bimmer only does around 8.5psi and hence the ~180hp difference.


    Not exactly - Porsche has 20% more displacement (335i has only 3.0L, despite name) and the BMW has MUCH higher compression ratio, due to the use of Direct Injection (so less boost needed for big power). To get 400hp from the 335i, you only need to add 2-3 psi more.

    See: www.vishnutuning.com

    Also, are both your cars automatic transmission? The greater lag you're feeling in the 335i could likely be due to the different (worse) automatic gearbox. 335i I drove had almost no lag at all (6 speed).




    I just bought a 335 coupe (still on the boat), but I did test drive a 335 sedan with the paddle shifters. I did not notice any lag at all including city and some highway driving, I thought it was much better than my TT as far as lag since I didn't even notice it and I do notice it in the TT.

    Re: Tale of 2 Twin Turbo engines (and some others.

    Quote:
    eclou said:
    turbo lag is not the same as transmission hunting.



    Yes but unlike you few people can tell where the lag is coming from. All they know is that they pushed on the gas pedal and the car hesitates before it goes. That's lag. And I'll bet that the automatic transmission is responsible for more lag more of the time than turbos.

    Re: Tale of 2 Twin Turbo engines (and some others.

    Ok, so I guess I wasn't clear enough, the bimmer turbo only lags on standing starts, it kinda pauses a fraction of a second before going, but after that the car is completely lag free. That's the only difference between it and the 997TT, in the Porsche it just rockets away right away.

    hatchback: don't knock on eclou, you WERE describing transmission hunting in your first post. And eclou is right about automatics, the torque converter mask the lag pretty well as it does keep the rpm up and the turbine spinning.

    atomic: this one I think I will leave it as is, I know about the tuning as I have been hanging out in the Bimmer forums too But as it's my wife's car I am not going to pay too much attention to it. But boy do this motor makes some serious power.

    grant: my bad on the displacement, didn't bother to check, I was all over the car when I heard it has twin turbo, and every word after that from my salesman was a blur..........

    NBERRY!!!!!!!!!!

    I knew I will get something from you when I brought up the F430 Those are still fantastic engines, but as you can tell I am a torque whore, not a rpm whore, hence y preference in engines.

    If I live on the track, I would love to have those engines, with them singing at 4k-8k rpm all day. But too bad I don't live on the track, and I prefer the instant gratification of low end torque than high rpm pull in street driving.

    Re: Tale of 2 Twin Turbo engines (and some others.

    Quote:
    hatchback said:
    Yes but unlike you few people can tell where the lag is coming from. All they know is that they pushed on the gas pedal and the car hesitates before it goes. That's lag. And I'll bet that the automatic transmission is responsible for more lag more of the time than turbos.



    Fair enough. Any delay (lag) would be frustrating no matter what the source. I hated my 996 tip b/c it always defaulted to starting in 2nd gear.

    Re: Tale of 2 Twin Turbo engines (and some others.

    Bang for the bucks the 335i is one heck of a car. I really like what BMW has done with this car. However I would not even think about comparing these two cars, two different leagues all together.

    Re: Tale of 2 Twin Turbo engines (and some others.....

    Quote:
    nberry said:
    I would consider the F430 V8 and the V10 in M5 and Gallardo coming in after the Porsche unit bcause they make absolutely no torque down low and needs to rev alot to go anywhere. Almost feel like they have the turbo-lag in a non-turbo car. I think of them as gyroscopes, sure spins like crazy but they don't actually go anywhere.

    Yea, they are slugs. Ferrari, BMW and Lambo should be ashamed of themselves for putting on the street such dogs.

    I find interesting that in the past few days TT owners are defending the car as much as they do. Subconsciously are they uncertain or disappointed in their purchase?


    Nick,
    I really hate to break this to you but when you are cruising at 3,500- 4,000rpm on your fancy 430 and you actually step on it you get approximately 200hp less than someone with a 997tt with 10k usd worth of mods doing the same thing. And for some people that would be enough to exclude a V8 ferrari. Hell if you were "forced" to use one of those 997tt for a few days you may also come to the same conclusion.
    Some of us happen to like and enjoy the "push" more than the mere acoustics of a ferrari engine struggling to come close to the red line for some power to finally emerge.
    Then again it all comes to personal taste..

    Re: Tale of 2 Twin Turbo engines (and some others.

    Quote:
    Whoopsy said:
    Ok, so I guess I wasn't clear enough, the bimmer turbo only lags on standing starts, it kinda pauses a fraction of a second before going, but after that the car is completely lag free.



    Per my initial post, maybe your 335xi is programmed to start in 2nd gear, like many automatic transmissions? If so, it will downshift to 1st under hard acceleration which will appear to you as lag.

    If your 335xi has a manual mode that lets you choose a gear, you can try to start the car from a standstill in 1st gear and then see whether that reduces the lag. You may be able to further reduce the lag by holding the brake while lightly touching the accelerator, which will help to lock up the torque converter more quickly and also will get the engine out of the lowest point on its torque curve.

    Let us know what happens...

    Re: Tale of 2 Twin Turbo engines (and some others.

    And that defeats the purpose of having an automatic. If I were to do so many steps just to get off the line, why don't I just get a manual instead?

    Anyway, it doesn't really bother me, it was just an observation when I compare it with the 997TT. Plus it's my wife's primary car, not mine.

     
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