Lancia 16v head sequential twin turbo

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jmcpower
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Lancia 16v head sequential twin turbo

Post by jmcpower » Sun Feb 24, 2013 3:52 pm

Hi Guy ,
I would like to ask some questions based on Lancias Abarth triflux ecv2 engine with the sequential twin turbo engine . I am sure that most of us are familiar with this engine !
I am thinking of a twin turbo project on the Lancia 16v turbo engine with a twin turbo sequential set up with max turbo response and high rpm power and i would like your thoughts on this very complicated idea !

My Engine current spec:
Bore 85mm
stroke: 86mm
inlet vlave diameter :35.5mm flow:173,5cfm @.55 inch lift @10"
ex valve diameter:30mm 147cfm @.55 inch lift @10"
camshaft spec:
inlet:valve lift = 11,75mm duration @ .1mm= 280 inlet:duration@ 1mm =244 lift@ tdc 2,8mm set @110degr full lift
exhaust: valve lift = 11.05mm duration @ .1mm= 262 inlet:duration@ 1mm =234 lift@ tdc 1.4mm set @115degr full lift
power : 720hp flywheel @ 9120rpm @28psi
torque: 58kgm flywheel @ 5800rpm @28psi

There are two options of doing this .
Option A.
Fabricate two exhaust manifolds 4 into 1 design with 28mm internal diameter, and each manifold will use 1 exhaust port per cylinder isolated from the other ex port ....this will require a minor welding at the end of the ex ports close to the manifold flange !
2:Each ex manifold will direct the ex flow to its small turbocharger with a max capacity of 360hp at 30psi of boost.
3:Turbocharger number one will use all the available ex gas from the engine ,to spool as quickly as possible! when the max boost of 28-30psi is reached an external waistegate valve will direct the excess of ex gas to the turbine inlet of the turbo number two.
3:Turbocharger number two will be fitted with a turbine outlet valve being shut( after the turbine housing on the ex downpipe) that will control the ex gas flow for this turbo, starting to open at around 4,500rpm and 28-30psi of boost . On the compressor side of turbo number2, a one way reed valve will direct the air flow to the intercooler inlet pipe during the 1st stage (waistgate gases of turbo1 to tubine inlet of turbo2 ) and then at higher rpm when the turbo2 has reached a higher boost 28-30psi a throttle valve will be used to direct the flow to the intercooler inlet .

Option number 2:
Fabricate one exsaust manifolt with 4 into 1 into 2 design with 40mm internal diameter and attahed both turbos with a Y joint !
All other parameters and valves on the systems will be working same as option A.

My questions are :
1:Will option A benefit a significant turbo spool (at least 500-800rpm sooner )at lower rpm due to the fact that all ex gases will have to pass from the smaller diameter exsaust valves , ports and exsaust pipes ?How much the exsaust gas velocity will affect turbo response?
And if yes will this affect the cylinder ex scavage in a positive way (at lower rpm) since only one ex valve will be used to scavage the ex gases up to 4500 rpm(bearing in mind that we are using a long duration cam wiht lots of overlap)?
2:On a high duration turbo cam ,during overlap some of the fresh air-fuel mixture will probably escape from the exast valve ...giving additional cooling to the ex valve ! Keeping the flow shut on the second turbo at lower rpm ,will this cause an issue to the valves and valve seats ?
3:What are your thoughts on an inlet manifolt with a similar aproach ? with 8 separate inlet ports ? will this be a benefit or too much hastle for nothing ?

Thanks in advance !

Mike.

Guy Croft
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Re: Lancia 16v head sequential twin turbo

Post by Guy Croft » Tue Feb 26, 2013 11:10 am

Hullo Mikey!

I will get on your post this week, had a rare day off on Sun and on a mag shoot yesterday else would have done it already,

sincerely,

G
Guy Croft, owner

jmcpower
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Re: Lancia 16v head sequential twin turbo

Post by jmcpower » Tue Feb 26, 2013 9:32 pm

Hellow Guy ,

Take your time , its not urgent , I am sure we will have a lot to discuss on this topic and hopefully others on the site can lay their ideas down !

Thanks in advance ,
Mike.

Guy Croft
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Re: Lancia 16v head sequential twin turbo

Post by Guy Croft » Sun Mar 03, 2013 1:29 pm

To be honest I think the complexities of the setup are a bit beyond me. I mean in absolute terms - of course I know plenty about turbo setups etc. But here, well, it's all very hit & miss really without predictive software.

If it were me I would forget sequential turbos and run two separated small ones - one on cyls 1&4 and one on cyls 2&3. Instantly you have achieved a big improvement from wave separation alone - something that, I think, with the radical setup you contemplate, will cause you problems you'll never overcome.


GC
Guy Croft, owner

jmcpower
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Re: Lancia 16v head sequential twin turbo

Post by jmcpower » Mon Mar 04, 2013 8:13 pm

You are right Guy , this set up its too complicated to predict not to mention to put it into practice and make it work properly !
I could not figure out if using at low rpm up to 4000-4500, one exsaust valve /port per cylinder ,would flow more due to the higher velocity , compair to the traditional 2 ex valves/ports per cylinder?
Also how this new set up ( lets forget complexity of the sequential twing turbo for a moment) would affect the pumping losses and scavanging when using just one exs valve/port during lower rpm ?
I am possitive that Abarth found the answer when designing the triflux head ! I am just trying to get into the theory behind this set up, that i currently lack !

Any help would be greatly apprecited .

Thanks in advance ,

Mike.

Rich Ellingham
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Re: Lancia 16v head sequential twin turbo

Post by Rich Ellingham » Mon Mar 04, 2013 8:51 pm

Mike did the triflux switch between one inlet and one exhaust to 2 or both in the rev range, I do recal they were diametrically opposed with one inlet and one ex valve on either side of the head.

Rich
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jmcpower
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Re: Lancia 16v head sequential twin turbo

Post by jmcpower » Mon Mar 04, 2013 9:10 pm

The triflux head used on Lancia Groub S ECV2 had a twin turbo sequential system that was using 4 of the exsaust valves to feed one turbo and the other 4 to feed the secondary turbo that would engaged at higher rpm 5000+ ! On the inlet side there was a traditional inlet plenum that fed both valves on each cylinder through individual throtle bodies...one per cylinder !
On The ECV1 triflux engine i beleive that there was no sequential turbo set up ...just two turbos one on each side fed by 4 ex valves /ports ! Basicaly same as Ecv2 but no sequential system !

Uros Piperski
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Re: Lancia 16v head sequential twin turbo

Post by Uros Piperski » Fri Mar 08, 2013 12:27 am

What about using a variable geometry turbo and/or twin scroll in a single or twin setup like Guy suggested? It should be a lot easier to build and it should have better spool up than conventional design.

jmcpower
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Re: Lancia 16v head sequential twin turbo

Post by jmcpower » Fri Mar 08, 2013 7:21 am

Hi Uros ,

My current set up is a twin scroll single turbo with a billet aluminium compressor wheel !
Yes Variable turbine geometry turbos should spool faster ( they also have a surge limit when you try to spool them as fast as possible)but they are designed for diesel engines that ex gas temperature is lower than the petrol engines ,so their is an issue with reliability there ! Do you know if there is a variable turbine geometry turbo for petrol engines ?
You are right as guy said it would be a lot easier to use two smaller turbos probably with billet coompressor wheel that has a significant lighter rottating mass , as well as a larger air route since the impreller fins are thinner , and the shaft (where the fins connect on the center ) is a smaller diameter so allows more flow from given size compressor wheel.

Mike.

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Re: Lancia 16v head sequential twin turbo

Post by Infectus-Guy » Thu Mar 21, 2013 9:55 pm

Hey Mike, glad to hear you are pushing new mad ideas! I've been thinking a lot about the triflux and how it would be great to get some cylinder heads cast. I guess there's not enough demand especially as most people have a bonnet to worry about! Wouldn't the S4 super/turbo charged design be easier? The switch over might be hard but with a decent electromagnetic clutch it could at least be predictable, then having a ball bearing turbo would certainly give you an advantage over the original S4 design. I would love to see you make a mid engined race monster, lots of space for nice long exhaust headers and tall triflux heads! Keep us updated on your progress....
Guy
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