kambites said:
Scuffers said:
Just cause the throttle has closed does not mean the turbo instantly stops spinning, (unless you have no blow-off valve and thus force the turbo into surge).
so, assuming you can change gear at a reasonable speed, then assuming you using a decent ball-bearing turbo, (not some old crap 1970's style one) then I very much doubt you will suffer noticeable lag.
yes, running 3+Bar of boost will somewhat not help here, but using a supercharger will help counter this (as it will still be spinning like crap off throttle)
I wasn't really considering gear changes to be honest. It tends to be using the throttle make delicate changes to the line of the car through a corner that gives me problems with a turbocharger.
Anyway, it seems that the answer is that the supercharger has no effect on turbo lag at all, as such. It just provides a greater amount of "base power" from the engine for the turbo to operate on top of, meaning you can have a lower boost turbo to get the same overall performance? Basically adding the supercharger has almost exactly the same effect as increasing the capacity of the engine? That was my initial assumption, which was why I asked how much boost comes from each 'charger.
You missed the part about greater exhaust gas flow.....
There is no lag because the instant the throttle is depressed the supercharger bypass valve closes and you have instant boost from the supercharger, that boost turns to instant "higher pressure, hotter" exhaust gas flow as it exits the head flowing into the larger than normal turbine to spin it up instantly which in turn creates turbo boost from the compressor wheel....The turbo boost is now force feeding the supercharger, by force feeding the supercharger it's parasitic drag on the engine becomes less as does it's creation of heat in the process....and now the process repeats itself making instant throttle response at any rpm..
Here is a graph showing the boost effect of the combination
The MP62 supercharger is sized perfectly for the 1.8 ltr. 2ZZ with a 2.5" pulley which on it's own can produce 300whp at 14psi., the turbo is a Precision 6262 billet ball bearing which can flow enough air for 800+whp......When you combine the two the engine behaves like a supercharged AMG 55 V8 with it's instant torque...
The car can pull on the Hwy in fifth gear from 70 mph at 2900 rpm all the way to 9000 rpm without any hesitation.. With 400 ft tq. at 3800rpm there is no lack of power..
Here is a little post on Lotus Talk made by a French Lotus owner buddy of mine :
[quote]
hello
i must admit there is no meanings comparing an Exige with an Atom !
or do you wish to drive under 100 ° F, or under a storm ?
Frank wanted to make the best car for the canyons ! but still being usable in any situation ! i went to california and i took this opportunity to meet Frank and try this fastest lotus !!!
i shall say he did it and far better than anyone could think !
i have followed many forums and the evolution since 3 years of this fastest exige ever build !!
most of you are talking about something they do not know, i mean the performance of this car and the feeling sitting inside with 700 bhp pushing you !
now i will share my experience with you because i have been with frank in the canyon during 3 hours, so i can describe the sensation .
when the engine start i noticed the deep sound of the exhaust and the iddle as stable as my exige cup ! so easy that you cannot imagine what is under the bonnet.
then we took the HW and the car was smooth as any other lotus elise.
But when you open the throttle, you enter in a new dimension ... the turbo has simply no lag and the rivs climb up to 8500 so fast , the waste gate set the boost and the dump valve blow off at any gear shift with an incredible sound !
this car is so fabulous ! the power comes immediatly and the torque push the car to hard when you exit a corner, i felt like a video game !!
during 2 hours we were on the canyon roads pushing the rivs, the turbo and the adrenaline !!! fantastic sensation, easy and always predictable.
it is by far the best car someone could expect in the canyon ! light, fast, with a very smooth power which comes at each throttle opening.
the sensation are far more intense than any other prestigious car in which i have been in my life (includes F430 challenge, 997 GT2, Z06...)
a real and ultimate Lotus with the best engine ever ! the videos which i have seen before i went in the car cannot reproduce even a little of what you feel inside !
we should simply realized the incredible work, time, also money , but mainly passion involved.
it is easy to make critics, or funny comparaison, but frank did what he wanted : the most fantastic car for a ride in the canyons !
and still usable on hw, with Aircon and music ! (not possible with an Atom !!)
it is furthermore reliable, i have seen it as we have a long ride including slow traffic on HW !
thanks to Frank for this sublime opportunity ! and unique experience
now my Exige Cup racetrack seems a little less magic ! but i know what is possible and efficient to make it fantastic ...
so you can still put critics or comments, but it will not change what i have experienced ... and you cannot even imagine it ...
philippe (the french connection)
Listen to the engine rev on our little drive..
The other cool thing is the staged dual fuel system alcohol/gasoline....
