GordR

Right guys..

I am developing a 13b Fd3s race car..or circuit and sprint use in the UK...i want good power 500+ but it has to be ultra responsive..sooo..

I have had an idea..to run a twin setup ...inplace of the 1st turbo run a decent sized supercharger then using the 2nd control system run a large single turbo inplace of the 2nd turbo..

What do we think..is it poss? anyone done it? and what power do we reckon?

Discuss....

Ta

Gord

jgrewe

iTrader: (1)

Sounds possible mechanically, the fuel control and volume would be the problem. I would think it would require custom everything because of space issues. I would use a Vortech supercharger so you could run it on the opposite side of the engine from the turbo. With that setup you could run an aftermarket turbo manifold for the single hairdrier.
I have only looked at double supercharging briefly but never thought about doing it to rotary. Sounds like it could be fun...

pistonsuk

A much simpler setup that trys to accomplish the same thing is here:

https://www.rx7club.com/showthread.p...croll+manifold


Justin

GordR

Hi Guys..

Thanks for comments...certianly alot to think about...i know V.W have just developed a similar principle and have had big results... i just think it would work great for the purpose i am looking at... for hillclimbing and sprinting need a low of low down torque and power...but would mean i could still run a big single and gain the big power higher up.... but as you say lots of work needed!

jgrewe

iTrader: (1)

You may do some research on aircraft from WWII. I think this principle was used quite a bit.

mwatson184

You aren't going to get anything down low with a centrifugal supercharger either. Boost rises linearly with RPM with centrifugals (3000 RPM = 5 psi, 6000 RPM = 10 psi).

GordR

Well my idea was that i want the power from a large turbo such as t78/t88 but its no good to me as it only comes in say 4/4.5k ...so i need something that can develop power.torque lower down the rev range to compliment the LARGE turbo

RacerXtreme7

iTrader: (2)

Its possible to build (all you need is money and mechanical/machining skills). But like what mwatson184 said, your NOT going to get good low end response from a centrifugal supercharger. It'll have to be a positive type (be it roots, screw, lyshmn etc). Overall though, it'll be heavy, complex, suck up power (you now have parasitic crank loss from a super charger AND pumping losses from the turbo), it'll generate lots of heat, be costly, and inefficient. The only reason to do it was to be different then the rest of the Rx-7 community, because this has been done before on other cars (Mr2, Mini, etc). You want quick response and 500 hp, run a GT35RS with race fuel. That'll be the simplist and effective. You could also run dual T04E or smaller GT turbo's and still get great response and make high hp numbers.

~Mike...........

BklynRX7

Ive read up a bit abotu twin charging before, but like someone said earlier the arrangement becomes the problem. If you use a centerfuguial then you will not get enough spool when you want it to warrant the work, if you go with twin screw or roots them you will have to place them after the TB and they might pose a restriction when the higher boosting turbo charger kicks in. I dotn know muc, this is just what i deducted from reading.

GordR

Thanks for all the comments guys...may have to give this one miss me thinks... may look into Mikes idea..or just go with a more modern Garrett..for me its about being different,.,..iits a showcase for the company and i want to stand out.

RacerXtreme7

iTrader: (2)

Although its been done.... twin turbos work well in spool and in power, and it makes people drool

~Mike..........

jgrewe

iTrader: (1)

I'd lean toward twin turbos as well. How about a different rear end gear to get the car into the rpm range for the turbos to spool quicker. Of course then you may have to much torque multiplication and break the tires loose when the turbos come on hard. Damn, there is always something...
How about a simple shot of nitrous to help those turbos along at low rpms?