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kambites

38,076 posts

101 months

[news] 
Wednesday 28th March 2012 quote quote all
Scuffers said:
OK, let's break this down, in the context of a BIG turbo, what causes lag?
The fact that on closed throttle, there is only a low volume of exhaust gas so the turbo is spinning slowly; when you open the throttle initially, the turbo is generating no boost so initial combustion cycles do not have much intake pressure so don't generate much exhaust gasses. It's a feedback loop between exhaust gas and intake manifold pressure that takes many revolutions of the engine after you open the throttle to stabilise

I don't think the size of the turbo has much to do with it as such (although I suppose the physical mass of the turbo will have a minor effect on the time it takes), just the peak pressure it generates? Even if the turbocharger itself was massless, you would still get turbo lag.


Again, I am ONLY talking about high rev off- to on-throttle transitions. Nothing to do with how the engine behaves at low revs.

Edited by kambites on Wednesday 28th March 10:19

Du1point8

15,510 posts

72 months

[news] 
Wednesday 28th March 2012 quote quote all
id there any other links??

The main one works but the other 2 don't.

Scuffers

12,648 posts

154 months

[news] 
Wednesday 28th March 2012 quote quote all
kambites said:
The fact that on closed throttle, there is only a low volume of exhaust gas so the turbo is spinning slowly; when you open the throttle initially, the turbo is generating no boost so initial combustion cycles do not have much intake pressure so don't generate much exhaust gasses. It's a feedback loop between exhaust gas and intake manifold pressure that takes many revolutions of the engine after you open the throttle to stabilise

I don't think the size of the turbo has much to do with it as such (although I suppose the physical mass of the turbo will have a minor effect on the time it takes), just the peak pressure it generates? Even if the turbocharger itself was massless, you would still get turbo lag.


Again, I am ONLY talking about high rev off- to on-throttle transitions. Nothing to do with how the engine behaves at low revs.
calm down...

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)

kambites

38,076 posts

101 months

[news] 
Wednesday 28th March 2012 quote quote all
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.

Edited by kambites on Wednesday 28th March 10:52

chuntington101

4,542 posts

116 months

[news] 
Wednesday 28th March 2012 quote quote all
kambites said:
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.

Edited by kambites on Wednesday 28th March 10:52
It will have an effect. as you say it will make the engine act like a bigger engine and thus will cause the turbo responce to be similar.

The boost generated by the supercharger will be dependent on how much boost the turbo is delivering to the supercharger inlet. the supercharger is just an air pump unlike the turbo that is referenced to the intake manifold presure.
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the ronin

674 posts

91 months

[news] 
Wednesday 28th March 2012 quote quote all
Du1point8 said:
id there any other links??

The main one works but the other 2 don't.
Fixed it

the ronin

674 posts

91 months

[news] 
Wednesday 28th March 2012 quote quote all
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.

Edited by kambites on Wednesday 28th March 10:52
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.. http://www.youtube.com/watch?v=59JrkPF-SVA

The other cool thing is the staged dual fuel system alcohol/gasoline....wavey

Scuffers

12,648 posts

154 months

[news] 
Wednesday 28th March 2012 quote quote all
kambites said:
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.
that's not a limitation of a turbo per say, just the control system around it.

sounds to me like you have only driven something with a really badly implemented turbo?

there are plenty of turbo cars out these with very good throttle progression, it;s not hard to do these days with decent electronics.

the ronin

674 posts

91 months

[news] 
Thursday 29th March 2012 quote quote all
Dude there is no turbo alone that can produce the 680whp out of the 1.8 ltr. 2ZZ and have the throttle response in every rpm as the compound charger setup....
I had to redesign the exhaust manifold to prevent the 56 psi boost spikes from a conventional turbo alone exhaust manifold. That is a good indication of how much better the spool up response is with the compound charger setup..

Exige77

1,522 posts

71 months

[news] 
Thursday 29th March 2012 quote quote all
Frank, why did you can your 2Ltr set up and go back to 1.8 ?

Ex77

kambites

38,076 posts

101 months

[news] 
Thursday 29th March 2012 quote quote all
Scuffers said:
that's not a limitation of a turbo per say, just the control system around it.

sounds to me like you have only driven something with a really badly implemented turbo?

there are plenty of turbo cars out these with very good throttle progression, it;s not hard to do these days with decent electronics.
I've driven ones that are often held up as good like the 335i and to me it felt absolutely awful.

the ronin

674 posts

91 months

[news] 
Friday 30th March 2012 quote quote all
Exige77 said:
Frank, why did you can your 2Ltr set up and go back to 1.8 ?

Ex77
Dude that was 2yrs ago, a broken valve did that engine in at 4,000 rpm while crusin down the Hwy.....

Here is a funny post from my French Lotus buddy Philippe to the haters on Seloc after his ride with me last week..

Philippe said:
hello
you are all jelaous of Frank or what ? this man keep his passion alive, he makes what he says, and none of you has tried his car ! so shut up ignorant pigs !

Frank wanted to make the best car for the canyons ! but still beeing 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)
I think that puts it out there for the haters.......another Exiges buddy AndyD is making a stop over this Saturday I'll see if he can give a unbiased opinion after our canyon cruise..

Edited by the ronin on Friday 30th March 07:03

SeanyD

2,910 posts

80 months

[news] 
Friday 30th March 2012 quote quote all
Frank, why the constant need to force down peoples throats how good the car is, that's the second time in as many days you've quoted Phillipe, to try and convert the haters.

Your car looks truly epic, and a masterpiece I'm sure, so why not enjoy it, be happy, be proud, any haters are more likely to be won over by giving us detailed unbiased write-ups of it's making, its challenges, what works, what doesn't etc etc, rather than forcing down our throats 'its epic in the canyons' time and time again.

I'm not a hater, genuinely facinated by your car, just a bit bored of the canyon stories over and over again.

Scrambled

586 posts

46 months

[news] 
Friday 30th March 2012 quote quote all
SeanyD said:
Frank, why the constant need to force down peoples throats how good the car is, that's the second time in as many days you've quoted Phillipe, to try and convert the haters.

Your car looks truly epic, and a masterpiece I'm sure, so why not enjoy it, be happy, be proud, any haters are more likely to be won over by giving us detailed unbiased write-ups of it's making, its challenges, what works, what doesn't etc etc, rather than forcing down our throats 'its epic in the canyons' time and time again.

I'm not a hater, genuinely facinated by your car, just a bit bored of the canyon stories over and over again.
Frank, I've criticised you on occasions but your car is spot on. You've had so many detractors I would ram it down people's throats too to be fair. Keep it coming dude. Love the work and wish I had the patience (and funds) to do what you have done.

Most of what is said about you does not take into account your 'marmite' personality but at your age I wouldn't be bothered by the detractors.

Keep up the canyon stories and videos. PH Elise/exige forum would be too dull without you fella.

the ronin

674 posts

91 months

[news] 
Friday 30th March 2012 quote quote all
Thanks dude, I feel if guys don't like the story from my lips read it from a guy that tracks and Rallys his Exiges can give an honest comparison between his GT2 and my Exige for acceleration...
That post got this response on Seloc and made me laugh..


I've turned into one of the old crazy gearheads I knew 30 yrs., These guys were the first Bonneville racers, Pikes Peak, La Carrera Panamericana and founders of the NHRA. The guys were always tellin stories of blown engines wild parties and adventure on the side of the road while tryin to put things back together with a coat hanger and duct tape...5 ft. blue flames out the back of a propane powered twin turbo Cadlliac doing 210 mph down the Hwy a 2:AM in 1982
I'm just tryin to show guys what can be done if you want to make it a better Lotus... I've already paid for all the R$D..

and if ya don't like what I have to say just STFU and move along

pilchardthecat

7,077 posts

59 months

[news] 
Friday 30th March 2012 quote quote all
Magnificent

Scrambled

586 posts

46 months

[news] 
Friday 30th March 2012 quote quote all
Calm response from you there Frank. This the new you? biggrin

the ronin

674 posts

91 months

[news] 
Friday 30th March 2012 quote quote all
Scrambled said:
Calm response from you there Frank. This the new you? biggrin
Nahh no need to use a sledge hammer any more since most of the haters have eaten crow by now and hopefully we can talk about making a better faster Lotus instead of whilly waggin..
Trust me nothing has changed...wavey

chuntington101

4,542 posts

116 months

[news] 
Sunday 1st April 2012 quote quote all
Found something that would be faster in the canyons than its the Norma M20 with the BMW 3l in the back.

Here is a vid smile

http://www.youtube.com/watch?v=qd1i1ZP3Aec

jasongtr

365 posts

130 months

[news] 
Sunday 1st April 2012 quote quote all
epic video, excellent car control
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