Check out this FI concept !!

[BIG8]

To bring the subject up to par, I admit I'm bad. I was surfing other message boards in the Forced Induction arena and came across something that a good friend of mine said he has. I did a search on this here and can't find anything on the subject. My Good friend owns a 95 Saleen Stang, one day we were talking about his car and I asked if it was S/Ced? He told me that it was S/Ced and Turboed? [img]graemlins/omg.gif[/img] WTF? was my answer giving him benefit of the doubt that he ment one of the two and wasn't sure, so I kept asking him if he was sure. I've seen pictures of him driving it and sitting inside after he got it and it's not his nature to make something like this up so keep the BS flags down please!!!! These guys in the other forum were discussing this concept of "twincharging" and the further I read the more genious it became to me!!!! I can go on for hours right now talking of how excited I am about this. It just seems like a mechanical and timing nightmare. You'd have boost through out your powerband [img]graemlins/omg.gif[/img] [img]graemlins/omg.gif[/img] Somebody, please don't let this one die i wanna go on with this one. What ya think? [img]graemlins/burnout.gif[/img]

[speedy-v6-camaro]

How would you setup the intake...you don't want to blow down into the turbo with the super and you don't want to blow the turbo through the super...that would decrease your effectiveness.

[Radcat]

I have heard of this before but it seems like it would be a pain to tune. That and the price of parts would be a lot.

[NCState98]

Some sort of one way valves on either the SC or turbo portions of the intake... or both? Does seem very far fetched, but halfway interesting in theory.

[nocutt]

WCF* did this already;

http://fieros.westcoastfiero.com/pix...nay/index.html

this was actually the simplest and least cost effective way to do it...the system is very complicated to say the least:
this is what the car looks like today; John Tinay aka spddy...enjoy!!
http://www.fiero.nl/forum/Forum1/HTML/043785.html

[Ian]

ever see those land speed cars? like 4 superchargers and 7 turbos

[GN-T66]

I've seen this before, on several applications... Seen it on a diesel generator, which was a detriot diesel.... also seen it on a tractor pull type vehicle.. that was a rolls royce merlin engine. In both cases, a turbo breathing into a roots type supercharger. hardest thing is the fabrication, tuning a setup like this would be no harder than any other forced induction setup.hardest part in my mind would be cam selection.... you'd want to keep the exhaust velocity up with a smaller exhaustr duration, but at the same time blowers like some duration on the exhaust to get rid of all the spent gases.

[njp98]

This concept is actually very old. If any of you have watched "Trucks!" on Spike TV you might have seen the old diesel engine (circa 1920's I believe). It used a turbo that blew into a roots blower. I don't know what benefits they thought it had. I also remember that they said this was the first mass use of a turbo on a mass produced internal combustion engine. Also they said early hot rodders took these same turbos off these old truck engines and used them for their hot rods.

[BIG8]

I did not know that NJP, learn something new everyday. Camming the thing would be difficult it seems? A roots S/C on our cars???? maybe a ATI Procharger? Boost control also seems like a hughe factor? You wouldn't need a hughe turbo or the smallest pulley to get some good PSI (well maybe a smaller pulley for the S/C to get a good pull on air, since you'd have to go turbo first it seems.) Would you require two intercoolers? one after each system, or just one insanely large intercooler? anyways [img]graemlins/naughty.gif[/img]

[njp98]

I think the system is pretty impractical for our cars. The intercooler would be only at the end (after the roots)to cool the charge, i've seen setups for this for the L67 in a GTP. However, if you used a procharger (or any centifical SC) it wouldn't make good low-end power like the roots (or a twin screw) setup would, which is the whole point of the SC - Turbo setup. Without the low end power this system would be pretty useless and would actually make less power than just a turbo alone I believe. Since the drive pulley would take a percentage of the power away. I think if you want the low-end and top end power ideally a sequential turbo system would be better with a mirad of 2 turbos and a couple wastegates so the smaller turbo spins up first and then the larger for when the load increases for top end. Also, ideally a variable valve system that is tuned with the sequential setup to provide maximum power could also be effective (although not on our engine obviously). This is all very complex and really not needed I don't believe on this car. You'd be better off building your engine and getting a big turbo (ball bearing, ceramic wheel,etc) and a small shot of nitrous (like from a little 2lb bottle) to spin it up early on (then it cuts out) this would probably give you better results anyway and be more reliable, and cheaper.
About the SC to pull air thru the turbo to help spin it up, there's been an idea similar to this. People have experimented with using an electric motor to help speed it up slightly for better low-end although it has to be one heck of a motor to spin than turbo shaft at something like 40,000 RPM(?).

[BIG8]

Interesting [img]graemlins/naughty.gif[/img] This is a complex conversation about the twincharging theory! I'm not as excited about it as I was a few nights ago. The concept is just very interesting to me, it's been a pleasure so far reading the replies. I agree that this would be very complex and expensive project, not to mention the modifications you'd probably have to make to firewall for the roots charger. An all out strip car or road car it would be something to keep in mind though? But as a daily driver looking for something to keep people guessing "what is under the hood?" I may just stick the original plan, a custom turbo kit.

"I think if you want the low-end and top end power ideally a sequential turbo system would be better with a mirad of 2 turbos and a couple wastegates so the smaller turbo spins up first and then the larger for when the load increases for top end." (NJP)

This seems a bit more trust worthy and less expensive. Just out of curiousity NJP, what sizes would you recommend for the Sequential?
Feed me info, [img]graemlins/popcorn.gif[/img] I'm like a sponge!

[RGB]

This seems easy enough if your starting with a L67 (with its electronics). The turbo feeds the intercooler the intercooler feeds through the MAF to the supercharger which feeds the intake manifold. Size the turbo for peak effiency at 15 psi 5,000 rpm on 3.8L. At low rpm the supercharger provides the boost (and gets the turbo spinning). At high rpm the supercharger becomes a nonfactor (open the bypass valve if necessary). Psi on each side of the rotors would be the same so no heat generated and no need for an intercooler after the supercharger.

PS for sequential turbos size the outside one for the effective sized of the engine with the inside one. For example if the inside turbo provides 5 psi of boost on 3.8L you effectively have 5.0L so the outside turbo should be sized to provide 5 psi of boost on 5.0L (total boost to engine is now 10 psi)

[njp98]

I think you'd still need an IC after the SC because any work done on air (presurization) follows the Gas Laws and hence the air pressurization (as well as the low efficiency of an Eaton Roots , about 70% as compared to about 90% with a centrifigal) so yes, you'd still want to have an IC, IMHO. I don't want to deter you from this project however, it could in theory work and you'd get an awesome full RPM band, although this would be very prohibitive ($$$$) but when you pop the hood people would [img]graemlins/omg.gif[/img] .

I'm not sure on the utrob sizing of a sequential system, there is a program (its like $15) that can assist you, but a better route is to keep askin' around here - I forget, but I believe someone on the board is making a twin setup (not sure if it's twin , 2 same size turbos working at the same time , or if its sequantial like that found in a supra. Goodluck with everything.

[T-Punk]

yeah, im working on the twin right now. it will be a twin t25 turbo not a sequential. Sequential in my opinion is too much work and offers little gains over a standard single or twin setup. oil pan is also working a the same type of setup i am but his is for the 3.4. My opinion on the superturbo would be to run the turbo to a an ic into a centrifugal into another ic and then put in the BOV and go into the tb. i dont see the problem with running the turbo throught the super but hey i have been wrong on things before. as for cams i would just keep the stocker, it is not to outrageous one way or the other and other turbo and super apps have been done with it with decent results. good luck if you try this, it will be a ton of work and a lot of money but will also be pretty unique.

[BIG8]

I may give it a shot, it'll be a while before anything is decided. I have to figure what would be best route for me. I've been talking to Tiago every now and then about a specific setup ( a TT for ya curious types) and man, I'm going for the [img]graemlins/omg.gif[/img] :eek: [img]graemlins/bowdown.gif[/img] (in that order) when I open up the hood, not to mention an all around gorgious and different Firebird. My goal is to try to have my car on a cover damn it!!! LOL if you have a cover! I plan to do the whole L67 conversion and then some = MADD BOOST possibilities [img]graemlins/naughty.gif[/img] But who knows, I'll plan and map out what will be going on under the hood, something in this thread will be done and you'll be posted on it promptly.
CCC