Twincharged 24v v6
Discussion
Hi ime new to ph, ime after picking some brains regarding twincharging.
I have a capri mk3 with a cosworth boa v6 engine ready for transplant, have you ever had one of those crazy ideas to create a monster and to ignore all of the people that say It can't be done?
I have an eaton m90 charger and I also have a holset hx 50 turbo which it a hefty sized turbo, I was contemplating either one or the other, then the thought crossed my mind "what if" then I started thinking how it could be done.
I believe the C.R of the boa is 9.7.1 which would obviously have to be lowered to accept safe boost of twincharging, then a custom plenum to accept nitrous the turbo outlet. The exhaust manifolds running to the big single turbo in a tickford style outlay with the inlet being fed directly by the eaton, obviously inter cooling and possibly charge cooling included. The co rods are the weak link in the equation and will be replaced with Williams forged rods, ARP bolts will hold everything together and best case scenario a type 9 quaife "dog box" as I don't think an mt 75 hybrid would take that much grunt.
I've been putting some thought into the pressure bypass between the eaton and the turbo because I don't want the charger to be a restriction at high boost.
So the big question is what have I undoubtedly overlooked and can it be done?
I have a capri mk3 with a cosworth boa v6 engine ready for transplant, have you ever had one of those crazy ideas to create a monster and to ignore all of the people that say It can't be done?
I have an eaton m90 charger and I also have a holset hx 50 turbo which it a hefty sized turbo, I was contemplating either one or the other, then the thought crossed my mind "what if" then I started thinking how it could be done.
I believe the C.R of the boa is 9.7.1 which would obviously have to be lowered to accept safe boost of twincharging, then a custom plenum to accept nitrous the turbo outlet. The exhaust manifolds running to the big single turbo in a tickford style outlay with the inlet being fed directly by the eaton, obviously inter cooling and possibly charge cooling included. The co rods are the weak link in the equation and will be replaced with Williams forged rods, ARP bolts will hold everything together and best case scenario a type 9 quaife "dog box" as I don't think an mt 75 hybrid would take that much grunt.
I've been putting some thought into the pressure bypass between the eaton and the turbo because I don't want the charger to be a restriction at high boost.
So the big question is what have I undoubtedly overlooked and can it be done?
Fuelling and ignition would be controlled by a mega squirt ms2 ecu, obviously I have a daily driver workhorse car ( toyota starlet) so the capri can take its sweet time and I feel ime free to experiment with it, I think if I can run a low ratio pulley on the eaton to minimise power loss hopefully the turbo would have spooled over enough to supply the engine with its own boost, my idea is to run a big turbo with minimal lag, even if you drive a car properly through the gears with a big turbo you will always get big lag, like the Porsche 9ff, massively fast car but slow as hell getting there. Plus ive never seen it done before so who's to say if it's worth it? Apparently the boa's where tuned down to 195 bhp from 300 because the auto gearboxes couldn't take the torque couple that with the loss of power restricting cats because it's a pre 91 car and I think there's potential for serious power.
It's been done many times before, and generally speaking, the results are poor. This is because the matching of the two pressure charging systems tends to be badly done, as often the turbo and superchargers are just what was found "lying around". Also, it's worth noting that it won't make the car any quicker than just a well done turbo conversion (because that's the part running at peak power).
It's also very heavy and complicated and in this day and age of clever electronic management i personally wouldn't bother doing it.
Of course, those are not necessarily enough reasons to stop you doing it, especially if you want something unique etc!
It's also very heavy and complicated and in this day and age of clever electronic management i personally wouldn't bother doing it.
Of course, those are not necessarily enough reasons to stop you doing it, especially if you want something unique etc!
Another thing to think about is intercooling. You are going to want to cool post turbo and then post supercharger. The post post turbo is obviously nice and easy (intercooler of some sort) but cooling the air post SC is not quite as easy. If you run a manifold mounted supercharger you will want to build in a charge cooler. This will obviously need a heat exchange with lots of nice cold air and not blocking the intercooler. You could also remote mount the supercharger, off to the side of the engine, and then run another conventional intercooler.
Key points I have noticed from twin charged setups is 1) you won't make as much power as the turbo only cars as you have the drag and inefficiency of the supercharger, and 2) you want make as much low down power as the supercharger only guys as you have to gear the supercharger slower for when the turbo comes on.
Could you sell the turbo and get a better suited one or are you stuck using the turbo?
Key points I have noticed from twin charged setups is 1) you won't make as much power as the turbo only cars as you have the drag and inefficiency of the supercharger, and 2) you want make as much low down power as the supercharger only guys as you have to gear the supercharger slower for when the turbo comes on.
Could you sell the turbo and get a better suited one or are you stuck using the turbo?
Also, is your blower volumetric or does it have internal compression?
I'd run with the turbo 1st, through an IC, then into the S/C (with a passive bypass valve) then direct into the engine. Running at low boost pressure and low speed means you can probably get away without aftercooling the S/C exit air.
I'd run with the turbo 1st, through an IC, then into the S/C (with a passive bypass valve) then direct into the engine. Running at low boost pressure and low speed means you can probably get away without aftercooling the S/C exit air.
Sounds like a bit to much plumbing to me 
The Swedish guys have just turbo'd the 24v with good results on e85 though.
The standard rods are fine depending on what number they have (early ones are weak), and the rod bolts just need changing. the colognes don't like high revs, as it breaks the 2 middle main bearing caps out
As for gearbox, I wouldn't hold out much hope of a type 9 based box lasting long at all, T5 would be the best option for squeezing in to a Capri
For more help or ideas, there's loads on the fordpower forum. Even several people on there running big turbo powered 24v stuff too
The Swedish guys have just turbo'd the 24v with good results on e85 though.
The standard rods are fine depending on what number they have (early ones are weak), and the rod bolts just need changing. the colognes don't like high revs, as it breaks the 2 middle main bearing caps out
As for gearbox, I wouldn't hold out much hope of a type 9 based box lasting long at all, T5 would be the best option for squeezing in to a Capri
For more help or ideas, there's loads on the fordpower forum. Even several people on there running big turbo powered 24v stuff too
Cheers guys, ime grateful for the advice.
I had a figure of around 500 bhp in mind with the right config but that's really ambitious, I know top boss have had good results with the engine but I've not come across a twincharged cologne yet so it's appealing in that sort of way it's just the strength of the block and internals that would be the downfall I suppose.
I had a figure of around 500 bhp in mind with the right config but that's really ambitious, I know top boss have had good results with the engine but I've not come across a twincharged cologne yet so it's appealing in that sort of way it's just the strength of the block and internals that would be the downfall I suppose.
hi teamwolf
theres a forum called eng tips , with a few threads on this by people that have actually done it ,heres one for example..
http://www.eng-tips.com/viewthread.cfm?qid=267889
general concensus seems to be it works very well , and gives a terrific under the curve area of trq.
re the holset , I would give it a try , remember , whatever boost you put in with the supercharger ,say 10 psi for example ,will increase exhaust flow ,in the case of 10 psi , by around 50%, so your engine will be making the exhaust flow of a 50% bigger engine ,which may fire up that holset nicely ..
I built a twin staged turbo to turbo tvr in the late 80's , using a small ihi ,and a big holset hc3. with the small ihi at 9 psi ,the holset came in at 3200. with no small ihi it was lucky to make 5 psi by the red line .in that instance the ihi was too small for the exhaust flow , but the trq curve and instantaneous response was great , and the big turbo definitely worked .
one other very enjoyable feature is the sound through the holset when you back OFF WITH NO DUMP VALVE... it sounds like a jet in reverse , most fun at the line at santa pod .
regards
robert
theres a forum called eng tips , with a few threads on this by people that have actually done it ,heres one for example..
http://www.eng-tips.com/viewthread.cfm?qid=267889
general concensus seems to be it works very well , and gives a terrific under the curve area of trq.
re the holset , I would give it a try , remember , whatever boost you put in with the supercharger ,say 10 psi for example ,will increase exhaust flow ,in the case of 10 psi , by around 50%, so your engine will be making the exhaust flow of a 50% bigger engine ,which may fire up that holset nicely ..
I built a twin staged turbo to turbo tvr in the late 80's , using a small ihi ,and a big holset hc3. with the small ihi at 9 psi ,the holset came in at 3200. with no small ihi it was lucky to make 5 psi by the red line .in that instance the ihi was too small for the exhaust flow , but the trq curve and instantaneous response was great , and the big turbo definitely worked .
one other very enjoyable feature is the sound through the holset when you back OFF WITH NO DUMP VALVE... it sounds like a jet in reverse , most fun at the line at santa pod .
regards
robert
I was running a Twincharged setup in my 1991 Toyota Corolla GTi-16. It used a roots type blower on the 4AGZE engine (1600cc) and a T04E/T03 hybrid turbo.
It ran two intercoolers, an electronic clutch on the supercharger to disengage once turbo was up to spool and a bypass valve.
Worked great, torque curve was unbelievable, still miss the kick.
That's what a well specced twincharge.system gives you, masses of torque all the way through the rev range.
It ran two intercoolers, an electronic clutch on the supercharger to disengage once turbo was up to spool and a bypass valve.
Worked great, torque curve was unbelievable, still miss the kick.
That's what a well specced twincharge.system gives you, masses of torque all the way through the rev range.
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