Psycholis

the amount of volume you add with piping, increased intercooler volume etc is what leads to more lag. the smallish stock turbo has a hard time coping with moving the large volumes of air that an aftermarket turbo can do in spades. nothing to do with boost pressures or ball bearings, just simple fluid dynamics.

joejoe69

iTrader: (2)

That's why i suggested for the hot side piping ID to be much smaller than pre-made kits, if not, matching the compressor outlet of the turbo to increase the air velocity. The pre-made kits are designed for more head room to allow turbo upgrades.

ds baruuuuu

iTrader: (16)

the lag is a myth.... my fmic is an ebay cxracing kit starts at 2in fron the turbo up to 2.75". the core is 24x12x3.. throttle response is slower but no lag.. sheit i have logs of me hitting boost cut (which is 18.4psi) at 2800 stock td04

dysfunctnl doll

iTrader: (13)

Written by Reid:
The real problem is the MAF lag, especially for those with fast spooling turbos and larger injectors. You get a pig RICH condition that’s difficult to tune out because it’s a timing issue with the injectors reacting too quickly. I’ve seen it done, but the problem is usually reduced but not eliminated. There’s a latency in the system to allow for the stock inlet and stock TMIC. When you change the volume or timing from when the MAF registers the air and when the air enters the chamber, you get a timing/latency problem.

Tuners often see the car go from 14.7 to 10.0-1 or even richer to 9.8-1. And it’s that rich condition that feels like lag. The car goes dead for a brief second and then when it leans out as the timing is correct, the car feels okay again. It’s more apparent with stock turbos running larger injectors. But like I said, it's possible to minimize if the tuner spends time in the car and plays with it, but it requires a lot of logging and street driving in different gears. You won't get that from a dyno tune.

On large turbos, it’s not a problem because they spool more slowly anyway, allowing the timing to not have a big differential. But a lot of the feeling is there. That’s why you can measure very little lag, but you feel the response suck it big time.


You can simulate the condition if you step on it, let it hit full boost and watch your wideband and then let off and do it again.
You'll see a rich spike
Just FYI

corytomo

iTrader: (3)

If you want, I have a 20x10 Spearco core with HKS endtanks for sale.. could always try and see if it fits before you buy the ebay core.



Bought it for $550 a few years back, went with a v-mount so never used it.
$400

joejoe69

iTrader: (2)

howzdawagon, don't be afraid of the ebay FMICs, they're not as bad as you think. They have good build quality next to the big names, no one that I know who has them had a problem with it. Most of the good ones are bar and plate design. Tube and fin type ebay FMICs arent that great. And most of all, they're affordable.

howzdawagon

i was never afraid to buy one i just was more worried about fitment issues

johndabrit

iTrader: (31)

welcome to turbo lag.

ds baruuuuu

iTrader: (16)

you are confusing lag with throttle response. like i posted earlier with a stock turbo and fmic in 4th gear i hit boost cut (18.4psi) at 2800 rpm. the turbo does not spool slower its a Maf rich issue as posted ealier

joejoe69

iTrader: (2)

All you have to do is buy the 02-03 (bugeye) kits, stay away from 93-01 (GC) kits and 04-09+ (peanut eye/hawkeye/new age) kits, as the intake manifold positioning and bumper designs are different.

True, as it usually happens right before peak torque.

I've been playing with my tune since last October and finally caught on a couple months ago. I had to lean my fuel corrections alot in that area to raise the AFR's a bit. Reid is right how it can't be eliminated, but reduced. I learned alot from my dyno runs at MunkyWurks.