Expert: Dan Liddy - 4/24/2004

Question
Hi, im in the process of of building a Nissan Silvia S15 racecar, which has a 2 litre turbo engine in it. as you probably already know.
Well me question is im thinking to upgrade to a larger turbo, I just dont know which way to go about it. I have a choice that will produce 500Hp with bit of lag or 430Hp with much less lag. I will be rebuilding the engine and all the goodies to to run this car healthy. I would like to know, around the track does the turbo lag play a part.


Answer
Hi Ray:

In the kind of racing I do (SCCA Road Racing) turbos aren't allowed, so I have little experience with them.  

However, I know from reading and talking to some road racing pros that turbo lag is one of the real problems they had in the early years.  For example, the Porsche 962 , early version, would go all the way thru a corner well under control, but when the turbo came on, the car would become extremely twitchy, and with an inexperienced driver, would get very loose, and sometimes go around. From personal experience, spinning out in traffic, above 100 MPH is a real eye opener.

Modern racing technology has made turbo systems much more drivable for racers, but if your form of racing involves corners, I think you would be better advised to stay with the 'no lag' system.

As a matter of fact, I just saw my first Silvia a few weeks ago, and stopped the guy to find out about it.  I have Datsun 510's and a friend tells me that the 2.0 turbo motor is the latest bolt-in conversion.  Thinking seriously about that, but race cars come first.

Good luck with your project !

Dan Liddy
Sarasota, Florida