Janspeed Twin Turbo conversion

[DrFelch]

Whats the space like in a cob/rovV8 for twin turbos ??? They seem to stick out the side like a large pair of ears it seems... Surely they cant fit..

From what I can see, you need to look at the compression ratio, stick new manifolds on, connect them to some kind of induction for the carb, connect them to the oil pump for oil cooling purposes, modify the sump for oil return.. Possibly intercooler too..

Any ideas ?

Marcus

[Philip]

Hi Marcus,
Ive got a picture of an engine thats been done with twin turbos and fitted into a cobra, will have to dig it up. Exhausts come forward to infront of the engine and turbos popped in place there then off back to where they should come out. I concidered this before going for the blower. Looked like too much work constructing manifolds, etc, and was concerned by how much heat they would generate under the bonnet.
As for compression ratio, Im running 9.75cr with 6.5psi of boost, no intercooler and Water Injection isnt even needed yet, currently around 300BHP, will be increasing boost to around 8psi very soon, around 330BHP, WI may be needed then, but no intercooler, as inlet air temp is only increasing by around 8C. But the blowers tend to generate a lot less heat than a turbo setup as far as I know, so you may need WI. In my opinion boosting the RV8 is the only way to acheive a reasonable power increase from them for the money. Ive got no idea how youd do it properly with carbs, would convert to EFI as its far far more accurate, especially for boosted engines and it will give you an increase in power as Martin Midmore has just converted his carbed 3.5RV8 engine to EFI and he is very impressed with it now. Hes about to stick a blower on his too.
As for oil feeds, etc, thats not too bad a job,
Phil

[osgood]

Marcus I too have a picture some where of a yellow Jobie which I will dig out. I did note that half the bonnet was removed though, due to heat problems and ten miles of pipes and wrapping!! As phil said go for blower with better results, and far less installation problems Eric

[DrFelch]

Thanks for the replies chaps. I see you point about the supercharger, but this actually looked more complicated to setup !!! (sounds like its not the case). I really like the feel of turbos too (brings me back to the little Ren5 Turbo days !!!).

I have been following your site Phil for quite a while and I cant believe you are getting that much power from a 3.5 !!! You seem to know what you are talking about and it still looks bloody complicated to me...

Marcus

[robert]

>Thanks for the replies chaps. I see you point about the
>supercharger, but this actually looked more complicated to
>setup !!! (sounds like its not the case). I really like the
>feel of turbos too (brings me back to the little Ren5 Turbo
>days !!!).

Superchargers are far easier to run than turbos, there are no heat issues, no exhaust recirculation problems, no issues with turbos spinning after you have shut the engine off and the inherent oil delivery when the turbine is still spinning etc etc etc.

It is also a smoother delivery which helps in a RWD car. :tu :tu

[Philip]

Hi Marcus,
as Robert says, superchargers are the easiest to setup and run, beleive me I would have fitted a turbo if it had been easiest. Maybe Ive explained it badly on my site and made it sound worse than it is, sorry if thats the case. If Id have fitted a turbo my site would have been even more confusing!


I was told by a few people that I would be OK up to around 7-8psi (300-330BHP) with the standard rover pistons at 9.75cr, Barry Davolls runs his 5.1 RV8 at 10.5cr and more boost than me, not standard pistons though, and has no detonation with no intercooler! I have a mate who lives in Sweden, and his 3.5 is up to 11 psi using standard 10.1cr pistons that have been worked on to get down to 9.4cr. At 8psi he was on the dyno at 340BHP, he has no intercooler but runs Water Injection. Im at 6.5psi at present, around 300BHP, hoping my engine will take up to 8psi, which should put it at 320-330BHP.

So 300+ BHP is fairly easy to acheive as long as you can fuel it properly and keep away from detonation. I have started off with low levels of boost and slowly increased it curing problems as and when they come up and taking advise from as many people who wernt bored of me bugging them.

Fueling a boosted engine with a carb isnt something I would want to take on, EFI has to be the way to go first if you want to go the boosted route. Then youd need an aftermarket ECU, etc. Carbs are too untunable to risk it with boost unless you know what your doing, and I wouldnt know!

I looked into 4.6 RV8s etc, 240-250bhp is about right for them, even the TVR 5L RV8 engine is only around 260bhp, and the prices for these engines are quite high. So I went for supercharging my little 3.5, with every intention of going over 300BHP which I have acheived at around £1500,
Phil

[Philip]

Twin turbo pics, carnt remember who sent them to me,
Phil

[DrFelch]

Cheers Robert/Philip. This is the sort of info I was looking for. Something to look at in the future I suspect !

Marcus

[Philip]

Marcus,
buy this book, its really good, takes a bit of digesting to start with and hes pretty good at contradicting (no I cant spell) himself, http://www.amazon.co.uk/exec/obidos/...771166-3596464 he also does one on turbos, might be worth buying both to do a comparison,
Phil

[DrFelch]

Excellent, definately worth a purchase ! Seems like Turbos are a no brainer when you look at them both together.

I sent you an email with a few questions off line if thats ok (to your address on your website).

Marcus