View Full Version : Paralell or sequential
Am soon to be having 650cc injectors, 264 cams and emanage fitted. Will be keeping the stock tubbies for now ( until saved enough for single turbo).
Would i be better switching them to paralell mode, or leave them in sequential mode?
Thanks
sorry to but in on your post.
what are the advantages of running them paralell apose to sequential
I hate parallel (true twin), there's too much lag (don't let Paul K read this), nothing until 4k then BANG the rear wheels spin in pretty much any gear!!
Advantages are more boost therefore more power at high revs, but disadvantages are NO power at low revs, and annoying lag. Bit like a big single then!! :p
If you look at the torque graphs side by side, you'll see the sequential has a hump of torque at low revs, then after 4K a bigger hump.
The 'parallel' graph has just the second hump.
Stick with the sequential system or you'll have a really PITA to map. And you're less likely to be happy with the fueling if you're fighting the stock ECU like this.
I know obviously a single goes against the sequential programming in the ECU but it's a completely different map anyway....
I found true-twin awful, and I can't see how it can give you *more* boost than you could get in sequential?!
I found true-twin awful, and I can't see how it can give you *more* boost than you could get in sequential?!
Maybe cause it's less controlled than the sequentials!! Maybe it's cause the first turbo doesn't run at the same pressure as the 2nd one in sequential mode ;) :p :lol:
I was on true twin (full de-cat) - Never going back to it purely because the car becomes way too loud! Motorway driving becomes unbearable. Even at Idle - It's much louder, a horrible sound. Don't know how to descibe the sound but I didn't like it.
Stick with the sequential system or you'll have a really PITA to map. And you're less likely to be happy with the fueling if you're fighting the stock ECU like this.
I know obviously a single goes against the sequential programming in the ECU but it's a completely different map anyway....
I would have thought it would have been easier to map in paralell as you wouldnt have to worry about the transistion between the two turbos???
Or am i talking bollox!!!!
i hated TTC too, car sounded like there was a cat (feline type) stuck in the exhaust!
Suprasteve
04-07-05, 16:36
would you get a better 1/4 mile time in Paralell as the rpm will always be above 4,000 (apart from 1st gear unless you managed a good start) i.e. taking advantage of the higher boost compared to seq above 4,000 rpm.
anyone tried both down the drag strip on the same day ?
I would have thought it would have been easier to map in paralell as you wouldnt have to worry about the transistion between the two turbos???
Or am i talking bollox!!!!
Nah, cause it's the stock ECU you're trying to fool...the stock ECU is only mapped for the sequential system - it dumps in extra fuel when it's expecting the 1st turbo and extra timiing etc...you're fighting this when you go to map it for a single.
With carrying on in sequestial mode you could conceivably(sp?) carry on with just the Global correction factor, but I don't think this would work completely, esp if you're using more than stock boost.
would you get a better 1/4 mile time in Paralell as the rpm will always be above 4,000 (apart from 1st gear unless you managed a good start) i.e. taking advantage of the higher boost compared to seq above 4,000 rpm.
anyone tried both down the drag strip on the same day ?
I think that statement is wrong. Above 4,000rpm both turbo's are working the same, together whether its in Seq mode or TT mode. The only adv you could gain is if you removed the plumbing for the sequential system and had independent feeds to the two turbos.
Nah, cause it's the stock ECU you're trying to fool...the stock ECU is only mapped for the sequential system - it dumps in extra fuel when it's expecting the 1st turbo and extra timiing etc...you're fighting this when you go to map it for a single.
With carrying on in sequestial mode you could conceivably(sp?) carry on with just the Global correction factor, but I don't think this would work completely, esp if you're using more than stock boost.
Cheers for clearing that up Alex. It shall be mapped by Ian C, so hopefully he shoulnt have too many problems sorting it. :thumbs:
Suprasteve
04-07-05, 16:50
I think that statement is wrong. Above 4,000rpm both turbo's are working the same, together whether its in Seq mode or TT mode. The only adv you could gain is if you removed the plumbing for the sequential system and had independent feeds to the two turbos.
Thats what i thought but someone told me different. So yes, surely all your doing is removing the first hump on the graph, the second will remain the same as both tubs are doing the same thing as in the seq mode and overall bhp will not change.....if you get my drift :drown:
I've been running mine in parallel for over 5 years now and have similar mods to you Smarty. I was advised to go to parallel by my tuners here (HKS pro dealer) who said that it was easier to map the e-manage and extract more power with the turbos running in parallel.
I much prefer the smoother power delivery of the parallel setup, see dyno graph in link below in my sig.
How long have you had your stock tubbies at 1.25bar?
How long have you had your stock tubbies at 1.25bar?
Exactly the same amount of time, because I had one of the stock turbos blow on the dyno run when the e-manage was originally being mapped.
I had 2 new stock turbos fitted and car mapped, that was over 5 years ago, maybe 6 years now.
steady_eddie
04-07-05, 18:35
heckler couldnt decide this either so he's got a lil button that he presses every now and then to switch between the two, dont ask me how it works tho, all i no is his car is like warp speed 9
I presume that at about 3800 rpms the ECU alters the timing or something to allow for the second turbo coming online. Is that why people say its harder to map around this area???
:shrug:
Hi all :)
I saved out someone's dyno plot once of a parallel conversion. I've attached an annotated version which shows exactly what goes on compared to sequential mode.
You can see the boost pressure curve of both modes of operation. Sequential absolutely kicks the arse of parallel up to about 3350rpm. Then, parallel gets up to 1 bar by 3500rpm, therefore being better for 150rpm. After that, and this is the traction-breaking moment that makes parallel mode *seem* more powerful, there is a really nasty boost spike to 1.3bar - scary when the boost pressure is supposed to be 1.0bar. This lasts for 400rpm before the wastegate opens - the wastegate isn't used until about 3900rpm because the stock ECU doesn't need it to control boost until then - as far as it's concerned, the EGBV controls boost until then.
As you can see, by 4000rpm the wastegate has dragged things back under control and the boost pressure, and therefore power, is exactly the same as sequential mode No higher boost, no magic increase in performance, nothing.
So, parallel gives you:
150rpm (count 'em) of safe higher boost than sequential mode
400 rpm of scary boost spike (the higher your target boost the higher this spike will get as it's basically no wastegate control :eek: )
A *lot* less power under 3350rpm
No difference above 4000rpm
Hmmm. You can use parallel if you want but I think it's rubbish :)
-Ian
Thanks for that Ian. Was interesting seeing the difference between the two setups on a graph.
I will stick with sequential operation me thinks, dont want no nasty spikes causing me grief.
Cheers all
The graphs I've got say a similar story (http://www.max-boost.co.uk/max-boost/supra/technical_details.htm#sequential_parallel_comparo)
Also if it's a wired one like mine it makes your vsv rattle like a bastard when on overrun!!!
Mine now rattles anyway after using ETTC a total of 3 times!!!
The graphs I've got say a similar story (http://www.max-boost.co.uk/max-boost/supra/technical_details.htm#sequential_parallel_comparo)
Can some one ask JohnA where he got the numbers from? I'd really like to see the dyno sheet as I'm slightly confused by some of the numbers it's showing.
I'm on his ignore list :violin: :lol: so if someone could just quote this in a new post he'll see my request.
Can some one ask JohnA where he got the numbers from? I'd really like to see the dyno sheet as I'm slightly confused by some of the numbers it's showing.
I'm on his ignore list :violin: :lol: so if someone could just quote this in a new post he'll see my request.
Alex you :nana: those are Excel charts not dyno sheets :D
I've got the power and torque curves from the same dyno run that the boost curves came from, I'll post them up when I get home tonight. They don't look much like those Excel charts though - 350ftlb at 2000rpm?! I wish :D
-Ian
You can see the boost pressure curve of both modes of operation. Sequential absolutely kicks the arse of parallel up to about 3350rpm. Then, parallel gets up to 1 bar by 3500rpm, therefore being better for 150rpm. After that, and this is the traction-breaking moment that makes parallel mode *seem* more powerful, there is a really nasty boost spike to 1.3bar - scary when the boost pressure is supposed to be 1.0bar. This lasts for 400rpm before the wastegate opens - the wastegate isn't used until about 3900rpm because the stock ECU doesn't need it to control boost until then - as far as it's concerned, the EGBV controls boost until then.
As you can see, by 4000rpm the wastegate has dragged things back under control and the boost pressure, and therefore power, is exactly the same as sequential mode No higher boost, no magic increase in performance, nothing.
-Ian
Hello Ian,
Maybe you can confirm this for me but I get the impression that when most people install boost controllers, regardless if its manual or electronic they seemt to plumb them in parrallel/series to the stock ECU boost control.
Would it not be far easier if switching to true twin (not that i would have) that you completly bypass the ECU control and use a seperate controller.
Is there any need for the stock ecu to still have any control over whats happening turbo wise if you have another boost control method setup correctly?
:thumbs:
MONKEYmark
05-07-05, 11:19
would you get a better 1/4 mile time in Paralell as the rpm will always be above 4,000 (apart from 1st gear unless you managed a good start) i.e. taking advantage of the higher boost compared to seq above 4,000 rpm.
anyone tried both down the drag strip on the same day ? i once tried on stock tc
13.7 on ttc
13.2 on seq
on stock stall in ttc is like you put your foot down and wait and wait then whhhooooaaaaaa its off like a rocket. you cant really launch any harder as tyres just start spinning on spot. in seq you just seem to get off line better.
If you manage to keep it above 4Krpm in both cases, I don't see any reason for any of the two setups to have an edge.
Airflow will be the same, so will fuelling and ignition.
But if you use the rev range below 4K, then the sequential will start having an advantage, with more torque available and the ECU having more optimised curves for it.
If you manage to keep it above 4Krpm in both cases, I don't see any reason for any of the two setups to have an edge.but you can't pull away at 4000RPM because the stock torque converter restricts power braking to a max of 2000rpm
exactly.
Plus the original question was from someone with a manual, wasn't it?
It was indeed but MonkeyMark's post was about an Auto.
I thought I was replying to your reply to Mark. (IYSWIM)
No probs.
Hello Ian,
Maybe you can confirm this for me but I get the impression that when most people install boost controllers, regardless if its manual or electronic they seemt to plumb them in parrallel/series to the stock ECU boost control.
Would it not be far easier if switching to true twin (not that i would have) that you completly bypass the ECU control and use a seperate controller.
Is there any need for the stock ecu to still have any control over whats happening turbo wise if you have another boost control method setup correctly?
:thumbs:
Aha, I see what you are saying, yes - OK, you can possibly remove the boost spike with some careful tweaking of your boost controller and bypassing the stock VSV :thumbs: So you'll get about 500rpm of better performance rather than 150rpm ;) The bottom end will still be just as bad though.
-Ian
Suprasteve
05-07-05, 14:35
my conclusion...
so unless you've got a highly modded car and need remapping or just want better fuel consumption there is no real other advantage for changing from standard seq set up to true twin turbo set up.
Also unless you've fitted a boost controller in a special way the ttc set up could potentially cause boost spiking of around 1.3 bar which is a serious no no with stock turbos.
looks like i'm sticking to seq for the mo.
please correct me if i'm wrong.
thanks for all the knowledge, you knowledgeable people :respekt:
BTW, yes i have a manual.
John, what is the deal with those dyno charts Alex posted, I *think* they are Excel sheets too??? What type of rollers were they from??
John, what is the deal with those dyno charts Alex posted, I *think* they are Excel sheets too??? What type of rollers were they from??
Yeah, they look like Excel to me too.
They came from the same old Autospeed article. I could email it to you if you like, but it isn't a technical diatribe, more like a journalistic description.
No I will look throught autospeed as I have a memebership if you have the link?
no link, because these I had downloaded as units years ago.
It was called "engine ecstasy VVTi Supra Turbo"
if it was a white car I think I remember it
I've got it on my webspace along with their other supra articles at the time, if you can't find it I could PM you the link
Finally remembered to hoik these dyno charts out. The left hand one is torque, the right hand one is horsepower. It's easy enough to spot which are the sequential and which are the parallel curves - the parallel curves are the ones that sit low then spike just before 4krpm.
As far as I recall this car was boosting to 1bar so was mildly tweaked, fairly close to stock. The power figures reflect this. Note the values on this dyno sheet don't match the Excel chart posted earlier, torque at 2000rpm is 120ftlbs in Seq (certainly not 350!) and a piss-poor 60ftlbs in Par (definitely not 220!). Power figures are similarly disparate. Christ knows what the data behind those charts are from ;)
Anyone still interested in parallel mode? :looney: :D
-Ian
Anyone still interested in parallel mode? :looney: :D
i have a completely different experience of parallel. on that same dyno i made just under 400hp/tq with no boost spikes whatsover (blitz dsbc). the car had great afr's (powerfc) through the run and in general. i lost some area under the curve at low rpm, which i cared not about and gained some in the mid range, which i did like. i got a much friendlier curve, without that aweful dip and the risk of 2nd turbo interuption mid corner.
parallel does not make more peak power, it does make a stronger mid range.
i think the whole thing is totally subjective and the example you have chosen to compare is about the worst example ever :) the first time i tried parallel i thought it was dreadful, it didn't take long for sequential to feel weird.
i love parallel and i had it working great, so there! :)
could it be that your sequential was defective, with the valves not opening correctly?
Had you changed the rubber hoses with silicon ones?
I totally agree with you eyefi.
Ian, the comparative dyno results you posted, was this the same car, ie dyno'd in sequential and then parallel? Was the car mapped differently for sequential and parallel setup?
The e-manage on my car was specifically mapped for parallel operation, I don't get any boost spikes, just smooth, strong power delivery through the rev range.
could it be that your sequential was defective, with the valves not opening correctly?
Had you changed the rubber hoses with silicon ones?
no, it was functioning perfectly
no, rubber hoses.
I understand that direct comparisons between parallel and sequential will probably tend to favour the sequential, as the ECU fuelling and ignition curves will be better matched for that.
It would be interesting to see comparisons on the same car, with both setups optimised.
I totally agree with you eyefi.
Ian, the comparative dyno results you posted, was this the same car, ie dyno'd in sequential and then parallel? Was the car mapped differently for sequential and parallel setup?
The e-manage on my car was specifically mapped for parallel operation, I don't get any boost spikes, just smooth, strong power delivery through the rev range.
Same car back to back mate. You can't compare yours to one that has simply had the actuators wired open. I consider this dyno chart an accurate representation of the 'average' parallel mod on a j-spec car, without a boost controller installed in a cerain way or some serious ecu remap :)
-Ian
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