Sorry I don't have time to read through your project thread, but I assumed you also changed turbo when you upgraded from 390 to 550 hp? In my opinion, changing to a bigger turbo almost always increases lag, as you need much more exhaust to get it spinning. The best action to reduce lag would be building a stroker, as that gives more exhaust to spin the turbo at a given rpm. Correct choice of turbo compressor and turbine and A/R is also important.
Best regards, Johan
Best regards, Johan
This is MY opinion on the subject - slightly influenced by what my tuner has told me but more so by my experiences.
Basically, my remit to the tuner was a fast car with usable power, especially as I lived in London.
He designed my engine to give me just that. I had 390bhp and as I have said many times on here before, until I changed from my RS2 EM to a tubular item, I just did not know what lag was. Power would kick in at 2500rpm and rise very sharply and hold. 360 lb torque by 2750 rpm! A Few on here have been or driven my car and hopefully they can confirm this. The power was also very smooth which actually made it feel not quite as fast as it really was. The CR of my engine is 7:1.
Now I stand to be corrected by the mechanics out there, but I am led to believe the difference between 7:1 and 8:1 from a turbo engine is in fact quite large.
My latest mods, especially the essential bigger IC have ruined the way the car drives.
I now have 550+(?)bhp. I'm sure I will get a better 0-60 and quarter mile time at GTI this year, but out on the road, I reckon from A to B my original set up would probably have been quicker
So my bottom line is, if an engine is designed well to do a specific task, be it high or low compression, it should achieve those tasks with no (or little) lag.
But low CR definitely does not mean a laggy engine.
Finally, do not try and ask an engine to do what it has not been designed for - you will be disappointed!
Cheers
CHris
Basically, my remit to the tuner was a fast car with usable power, especially as I lived in London.
He designed my engine to give me just that. I had 390bhp and as I have said many times on here before, until I changed from my RS2 EM to a tubular item, I just did not know what lag was. Power would kick in at 2500rpm and rise very sharply and hold. 360 lb torque by 2750 rpm! A Few on here have been or driven my car and hopefully they can confirm this. The power was also very smooth which actually made it feel not quite as fast as it really was. The CR of my engine is 7:1.
Now I stand to be corrected by the mechanics out there, but I am led to believe the difference between 7:1 and 8:1 from a turbo engine is in fact quite large.
My latest mods, especially the essential bigger IC have ruined the way the car drives.
I now have 550+(?)bhp. I'm sure I will get a better 0-60 and quarter mile time at GTI this year, but out on the road, I reckon from A to B my original set up would probably have been quicker
So my bottom line is, if an engine is designed well to do a specific task, be it high or low compression, it should achieve those tasks with no (or little) lag.
But low CR definitely does not mean a laggy engine.
Finally, do not try and ask an engine to do what it has not been designed for - you will be disappointed!
Cheers
CHris
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