I think he should stick to n/a then he will have no complaints.

Guys you are all getting lag and boost threshold mixed up.

When you are above those rpm ad smash the gas pedal, Lag is the time taken for the turbo to build boost. If the engine was NA then the term used would be throttle response.Lag is dependant on post turbo intake volume (cooler, pipes, plenum).


Boost threshold is the rpm at which the turbo begins to make boost.
Boost threshold is primarily dependant on turbo size ignition timing and fuel mapping, but camshaft, plenum and exhaust manifold design have a large part to play.

Dump the timing on an xr6t to a few degrees ATDC and tell me what happens. You'll have full boost off idle but you'll be able to walk faster than your car can accelerate (not to mention your turbo will be melted junk after a few seconds). This is the theory behind launch control on WRC cars and turbo outlaw 10.5 cars that run manual boxes.

Last edited by xcabbi on Sun May 16, 2010 10:42 pm, edited 1 time in total.

Wow, 111mph in 11 seconds. not bad at all.

mate i duno what your goin on about buy in my xr6 t, my turbos already spooled by like 2000, there is s**t all lag mind you it is stock atm except for exhaust and no tune either, but i have no lag issues i love it, if u think a 4.0l has lag just wait till u go into a jap car with a 2.5l engine and a bigger turbo then ours... thats pretty hard to spool... major lag!

Hi I'm new to the forum, I've got a BA XR6T 4 speed auto 244 rwkw's from 10 psi custom tune, I think it was actually quicker off the mark up to 30 kph when stock than with the 10 psi tune, but after about the 30 kph mark it goes like mad and keeps going. I find that if I don't stall it up and just boot it the car tends to pause a little until about 2000 rpm then pulls hard.
I once owned a nissan pulsar turbo, that had so much lag that a bicycle was quicker off the mark, the Ford xr6t is pretty good really, it doesnt have the instant power off the line that a cammed V8 would have but once on boost it is very strong.
Mine is actually JTG Icom Li gas and runs well, it sounds like something is wrong with the car in this thread because by 70-80 kph foot flat to the floor mines been on full boost for some time, once above 30 kph it's boosting well (0-30 kph is the only time the speedo needle looks slow)