Turbo Lag - how big an issue?

[Shifty1303]

Hi all,

doing my research on S15's still before buying one and im now wondering what the turbo lag is typically like? If/when i get one I would want to be able to drive off-boost up to say 3500rpm (not sure what the stock lower limit is) for my daily commute but then engage the turbo after that for "enthusiastic" driving. how is the lag on the stock setup? and what can be done to the car to reduce turbo lag except for running an anti-lag setup?

I know some lag will be inherent in a turbo car and im not trying to eradicate it. I just want to make sure the lag wont be putting me off the road in a corner.

cheers!

 

[JDM_virgin]

there isnt much lag to speak of on the stock setup, turbo comes in around 2500rpm and being a 2.0 there is enough torque to pull it through under that. Also being 6 speed its geared closer so that helps with acceleration. Standard boost is only 7 psi so doesnt take long to build pressure. Stock intercooler is small so not much volume to pressurise when building up boost. as a stocker its fine for a daily and is still faster than most things on the road due to lightness.

bigger turbo/intercooler etc will affect lag etc but its all to do how its mapped and tbh with a good tuner lag with a basic 300hp setup will be non existant.

 

[Shifty1303]

7psi?? That's tiny. My vw runs 1.5bar stock guess that's to do with the size difference in turbos?

So the trick is to get it mapped properly so boost is incremental rather than dumped full on at a certain rpm?

 

[JDM_virgin]

the stock turbo is good for about 1.2 bar maybe 1.5 but turbo is a common upgrade. you can have it mapped to suite how you want it, you could have nothing until 5k if you wanted to then come in all at once. but yeah if you have a **** map then itll ruin the car

 

[hugh janus]

regardless of the size of the turbo or the engine, the lag is decided by your foot

don't want to drive on the boil don't mash the pedal into the floor, want a sedate drive somewhere don't mash the pedal

the turbo isn't a light switch, all turbo's spool progressively, Lag wouldn't suddenly throw you into a ditch mid corner

 

[Shifty1303]

is it common to have it mapped with a linear boost increase through a rev range? ie from 0-100% boost between 2500-3500 rpm? I think that would be ideal for me. Also could you elaborate on how a bad map will ruin the turbo/car? over-working it? does mapping it at too high a boost cause the turbo flutter I hear so often from S15's or is that due to the BOV? this turbo flutter is bad right (although sounds cool)?

 

[Auss15]

Ok, so you're a newbie to S15's and how they perform....If you want one buy a stock unit, learn a bit about the car and as your knowledge progression evolves ask the hard questions...Don't worry about BOV ppssssttt and lag and mapping because all those things are a sum of future upgrades and how much you want to spend..I would look at handling and brakes before I got excited about turbo's and PSI

 

[hugh janus]

Ok, so you're a newbie to S15's and how they perform....If you want one buy a stock unit, learn a bit about the car and as your knowledge progression evolves ask the hard questions...Don't worry about BOV ppssssttt and lag and mapping because all those things are a sum of future upgrades and how much you want to spend..I would look at handling and brakes before I got excited about turbo's and PSI

You said it so much more eloquently than I could have done :thumbs:

 

[Shifty1303]

haha agreed. very eloquent. thanks for advice.

I was planning to start with coilovers, wheels and R33 brakes as recommended to me in other threads. of course when the time comes I will seek further advice from these forums.

I was only looking at lightly modded cars to save a bit of money if i can find one with decent coilovers/exhaust etc already but as you recommend buying stock may be best as Im keen to learn while I develop the car.

 

[trancer96]

I'm confused by the terminology in this thread. Turbo lag is what happens when you dump all the pressure when you get off the throttle and have to wait for it to build up again (when you upshift at 7000 RPM, say). But a lot of this thread seems to be talking about what happens when the boost comes on from having been off at low RPM (where the exhaust flow is too low). That's not turbo lag - that's being in the wrong gear (assuming you want it to be on boost). The stock wastegate closes gradually in the transition area so you /do/ get a smooth increase in torque when you're driving sedately at lowish RPM. You're not going be surprised by a sudden burst of torque with a stock wastegate.

 

[Auss15]

Stock cars are still a powerful vehicle especially if you haven't driven one before....Start at that level or closer and as your experience grows add more performance mods...
Wrecking yards are full of S15's that fell into the inexperienced hands of a new owner...

 

[Shifty1303]

ok thanks for the advice just how light are S15s? trying to gauge the power to weight vs what I currently drive. I know RWD will make quite a difference too.

 

[rapid200sx]

Ok, so you're a newbie to S15's and how they perform....If you want one buy a stock unit, learn a bit about the car and as your knowledge progression evolves ask the hard questions...Don't worry about BOV ppssssttt and lag and mapping because all those things are a sum of future upgrades and how much you want to spend..I would look at handling and brakes before I got excited about turbo's and PSI

The above statement is the PERFECT answer, in my opinion.

 

[TomK]

Roughly 1250kg give or take

 

[hugh janus]

Stock cars are still a powerful vehicle especially if you haven't driven one before....Start at that level or closer and as your experience grows add more performance mods...
Wrecking yards are full of S15's that fell into the inexperienced hands of a new owner...

this totally, I've owned an S body for some 12years however not have driven one for 18months I am crapping it when I eventually do again, just take it easy, and try not to give it too much man foot.

 

[Shifty1303]

why are you crapping it? is it that touchy?

 

[hugh janus]

why are you crapping it? is it that touchy?

in standard form they can be unpredictable moreso in damp conditions

RWD doesn't drive like fwd where you can drive it quickly and not really be too concerned lose concentration a RWD (unaided like the Silvia and others are) it will bite you in the arse.

on SXOC winter is referred to as killing season and for a very good reason...

RWD is totally another story, this is why some insurance companies now insist on having prior experience of RWD before they'll insure you on a RWD....I know that doesn't make sense but it's true.

its very easy for the back end to let go

 

[Shifty1303]

in standard form they can be unpredictable moreso in damp conditions

RWD doesn't drive like fwd where you can drive it quickly and not really be too concerned lose concentration a RWD (unaided like the Silvia and others are) it will bite you in the arse.

on SXOC winter is referred to as killing season and for a very good reason...

RWD is totally another story, this is why some insurance companies now insist on having prior experience of RWD before they'll insure you on a RWD....I know that doesn't make sense but it's true.

its very easy for the back end to let go

ah right i see. thanks for the advice. beyond getting some wheel time in a less powerful RWD car is there anything i can do to prepare? is it just ESP that Silvia's lack compared to more recent cars?

you say "in standard form". does this imply things can be done to improve the predictability?

 

[hugh janus]

standard tyres are skinny, the suspension set up is geared towards GT driving so is softer, the brakes are fairly rubbish, making small but informed changes to these can make a huge difference.

 

[Rich]

If you are concerned then look into fitting Racelogic Traction Control. Unsure if it has already been mentioned but do some reading on it, apparently it's pretty good although I've never used it myself.