GT4EC - The GT-Four Enthusiasts Club

General Category => The Chill Out Room => Topic started by: Coyoteboy on March 12, 2014, 12:36:44 am

Title: And now for something completely different
Post by: Coyoteboy on March 12, 2014, 12:36:44 am

OK not that different, but not often done on 3S's.

I now have a supercharger. And a CT20b. And 2 W2A intercoolers. And the phrase "compound twincharging". And not enough room under the bonnet yet.

But since the engine needed rebuilding it seemed rude not to try something a bit different, not aiming for huge power, just gob-loads of torque from idle, so I'm following the same route as the old group B Lancia S4....
https://www.youtube.com/watch?v=c71jDPRVyRU (https://www.youtube.com/watch?v=c71jDPRVyRU)

I'll be feeding the supercharger with pre-compressed charge from the turbo (when it's spooled, before that it'll just be what the S/C can manage).

Yes, I know:
It's not the best way to max power.
It's not sensible. Or easy.
It's going to take some fun to control the bypass and transient points.
Putting the throttle downstream of the S/C needs very careful bypass and possibly BOV control in order to not snap the throttle plate.
Peak power is still determined by turbo flow at low pressure.
Inefficiencies multiply, leading to lower overall efficiency.
Compounded boost is the multiple of the pressure ratios...pressure ratio of s/c being ~1.5 with ease (7.5psi, by about 1500rpm, hopefully earlier), turbo being 1.5 minimum (7.5psi by about 2500rpm, should be earlier than stock as it has increased exhaust flow from the S/C to get it spinning) - leads to an overall boost of ~18psi by about 2500rpm all the way to the red line.

Title: Re:
Post by: cunning stunt on March 12, 2014, 05:26:14 am

Cool, I've always liked the idea of supercharging, if I had the ability/money I'd give it a go.
Good luck fella

Sent from my C6903 using Tapatalk

Title: Re: And now for something completely different
Post by: STEVEtheHUTT on March 12, 2014, 05:41:04 pm

oh f*****g YES bro! can ya stick it all on youtube so we can watch ya?? hahahahaaa ;)

Title: Re: Re: And now for something completely different
Post by: martyn_pryor on March 12, 2014, 10:19:06 pm

Here's me thinking it was going to be related to Monty python. D'oh ::)

Title: Re: And now for something completely different
Post by: Coyoteboy on March 14, 2014, 06:38:49 pm

I'm just wondering if it's worth dropping higher lift cams in there or if I'll just destroy the low end gains I could get with the low down boost of the super.

Found the drive circuitry for the supercharger bypass, just need to test it now.