• Protip: Profile posts are public! Use Conversations to message other members privately. Everyone can see the content of a profile post.

who will try it first?

22 April 2003
With all the discussion regarding the benefits of turbo vs supercharger, I did a little surfing to see if the 2 had ever been combined in the same car. It seems that this has been done back in 2005 on a VW golf! So what do you think, an autorotor CSTC combined with a LOVEFAB turbo? Best of both worlds? worst of both worlds? Certainly on the pricey side but interesting for discussion.
From Gizmag:
"By combining the performance-enhancing elements of supercharging and turbocharging, a customer realizes the benefits of both technologies. The belt-driven supercharger compressor provides high torque at low engine speeds. The turbocharger kicks in to provide added performance at higher rpms. When the turbo system reaches ideal speeds, the supercharger is declutched and an electronically controlled bypass valve directs air to the turbocharger, which delivers high-end power without the "lag" generally associated with turbocharging. "

another good article

Last edited:
It's also called "Duel charging" or "Compound charging"

Lancia was doing it way back in the late 70s/ early 80s

The Delta S4 is the rally car Vincent van Gogh would have driven. Mid-engined, all-wheel-drive, extra-light, all that stuff. But what sets the S4 apart and always makes us smile is its compound charging. In order to fight off the nasty effects of turbo lag on twisty, hairpin dirt courses, the Delta S4's 1759 cc engine was both supercharged and turbocharged. Developed with Fiat's tuning shop Abarth, this lag-free set up screamed out at least 550 hp from a 1.8-liter four banger. And, like all these cars, the actual output come race day was most likely higher, if not much higher.

Lack of displacement did affect torque output, and that meant that the Delta S4 could "only" accelerate from a standstill to 60 mph in 2.5 seconds. On gravel. We're laughing just typing. Point being, this was the first compound charged engine ever raced, and the S4 was one of the most advanced cars ever built. Lancia and the Delta S4 finished 1-2 in the 1985 RAC Rally. The 1986 campaign looked to be much more of the same, but then Henri Toivonen tragically crashed his Delta S4 and the gas tanks blew, killing him and effectively ending Group B forever. Still, what a brilliant maniac of a vehicle it was.


  • delta s4.jpg
    delta s4.jpg
    24.5 KB · Views: 82
Last edited:
Wasn't that the whole idea behind the MR2 superturbo?
I had a customer on Honda-tech who did this a few years ago. Results were relatively impressive, though his top-end numbers were much lower than we hoped. I think with more refinement, his setup would've been awesome.

I researched compound/sequential turbo charging to run a massive turbo while still being daily driveable(think 1000+HP). This means use a small turbo to spin the larger turbo up to speed, then bypass the small turbo completely and run strictly off the large turbo.

I decided to start the process from the beginning and ran the large turbo right off the bat. Within minutes of testing, I decided that the GT45R was easily driveable on it's own, so I abandoned the sequential idea in favor of the K.I.S.S. approach. The sequential system would've been a nightmare to test and tune. Just look at any FD3 RX7.
Why would top end numbers be decreased? The compound effect of the boost should net the same as the turbo alone minus the parasitic loss of the roots blower. If the top end is decreased then why not just dial up the turbo to get what you want/ need?
It does seem that the setup was a better option when turbo lag was a bigger issue. I agree that given current turbo options it would be unecessarily complicated and expensive.
and it would be a better fit it you are trying to make big power from small displacment...on the NSX we have good displacement, and its easy to get repectable power....

now if we wanted a drivable 1500 hp... :biggrin:
HKS made a turbo kit for the Supercharged MR-2 - they called it a Twin Charger.

Had an offer to trade my stock SC MR-2 for one, but thought mine was fine :)