does that go for the FC as well.... my intention is to put a 20b engine into a FC Turbo II and go from there, and i have plenty of $

 

It's not a Rx7, but Veilside did a tri-turbo Supra.


Well, I guess after reading that I better specify what kind of T88 I want. Do you have a pro/con about the Turbonetics T88 vs the gt42? RPM spool ect...

 

im going to ask red-rx7 to take a guess when a t88 will spool to ?20psi?
i dont have info on when the gt42 will spool..... YET!

 

You BASTARD! lol. That's basically my next set up! Fully built 20B with an innovative GT80 dual ceramic BB x trim 1.34 tan a/r. Trust this will happen I'm not one of those who says they're gonna do this and that, yet they never fall through. Anyways it'll be a while before this project is finished. Good luck with your set up man, you have a good idea. Post some numbers and info when you get it dyno tuned.

Peace,
Alex

 

I know this thread is a bit old (a few months), but I've always wondered, is there actually enough SPACE to fit 3 single turbos in a 20B FD? And while I'd think the obvious upside would be enormous power w/ practically NO lag, what would be the downsides, other than weight? (I dunno what the weight difference would be between a huge single vs. three small singles at that)?

 

IMAO having 3 turbos on a 20b has more to do with "look @ the money that I had to spend" over ANY performace gains.

 

The idea of 3 turbos is that they would have a smaller diameter than a large single turbo of the same flow rate, and therefore the 3 smaller turbos would have less inertia, allowing them to spool up quickly. My personal problem with this idea is that the 3 smaller turbos would probaly have closer to 1/2 the inertia of a single turbo as opposed to 1/3 the inertia. Therefore, I doubt that they would in fact spool up faster. Also, it would be difficult to position 3 turbos as close to the block as a single turbo, and the further from the block and the more bends in the pipe the less power the exhaust will have to turn the turbine. Additionally, a 3-turbo setup on individual exhaust runners would only get one exhaust putt per revolution, while a single turbo would get 3, so the single would have more putts for initial spool-up as well as a smoother turbine flow. This is all speculation on my part, but I think it has at least a small amount of merit for consideration.

As for fitment in an FD, it has already been done:
http://www.geocities.com/evilaviator/axia

 

We will see.
We're in the process of hunting down a supplier for some cheapie T3-60's.
Right now, it's just a mental exercise...


-Ted

 

Thanks guys for the replies.

John, while I'm no techie, I'm pretty darn sure a VAST improvement of 3 small singles over 1 large single would be the ability to move a greater amount of air, plus potentially much quicker spool-up, resulting in more power at lower rpms. This is important to me, someone who really doesn't like waiting for peak power at 4500rpm. So in that sense, I do think they'd provide a performance advantage.

Evil Aviator, I understand all of your points, but also factor in the amount of air necessary to spool one LARGE (sometimes HUGE) single is a lot...to the point that it's practically a necessity to have it feeding of both or all 3 rotors (depending on the setup). It kinda goes back to just how much air you can flow... and if you're going 3-rotor triple turbo, I'd think you'd definitely port accordingly, and would have pretty good flow per rotor (obviously more than stock), no?

Ted, whatcha got up your sleeve, huh?

 

Here are pictures of my fb with t-76 and now with a Gt-42.
Have 'nt taken it to the dyno hoping to do it soon.
http://memimage.cardomain.net/member...42_14_full.jpg
http://memimage.cardomain.net/member...42_25_full.jpg
http://memimage.cardomain.net/member...42_26_full.jpg
My car in may not look as good as the as the other projects that I've seen here
but I have done all work myself and made functional.

 

I think most of the regulars know what I'm up to...
The original plan was to go with a trio of GT2835's, but it's hard to justify $4000+ worth of turbos when the owner of the car can't afford them!
We started to look for alternate options, and the Garrett T3 "60 trims" look rather attractive.
You can get them under $500 each, and three of them would be about $1,000.
Better than $4,000+!

The big question is can they all fit???
I have an idea of how to stuff them all in.
The FC gives us a little bit more space over and FD, so it's a little easier to pull off in our FC.

We're looking to get this done by next summer.
If this triple T3's work well, we might step up to the GT2835's if the budget opens up.


-Ted

 

I don't agree with the statement that big turbo's take a long time to spool up; only if the A/R of the turbine is improperly sized for the application is that true. The same holds true for a mechanically-driven compressor, the smaller the wheel on the drive shaft, the more revolutions it produces in relation to the crank and thus more pressure produced. With a turbo for a 20B application for instance, people are generally (general statement here) in the 1.15 to 1.32 range. Why don't they go smaller you may ask? Well they could go with a 0.96 or a 0.72 but why not? Well, because they would be producing boost at a much much lower rpm and... they would max. out their available powerband that much sooner so like everything there is a compromise to be had and I think that most people driving street cars are choosing something in the middle that comes on around 2-3K and maxes out around 7-8K for a turbine with a comperable compressor that is in the most efficient "sweet spot" of the compression map most of the way.

It is unlikely that multiple turbos will be more efficient that a single large with a properly sized turbine when run in parallel. However, that brings up another point, what about multiple turbos in sequential? Ah...if you can control it with your ecu than great but I doubt most of us here have the $ to spend on an ecu that can control such valving which brings us to mechanical control. Wondering what to use as a reference...? Well, take a look at any multiple turbocharged tractor pull and you will see. These guys are running sometimes 3-6 turbos running in the neighborhood of 35 Bar...yes Bar not psi. They don't have (for the most part), ecu's controlling their bleed off, pop off and bypass valving, it's all through springs and pressure regulators, etc, and it works fine. The only issue there is that they have to sit and wait for all the turbo's to come on boost before launching which is good for dragging but not for the street so to me it would be tweaking the regulators and not having to wait for such high amounts of boost to utilize it.

 

i have found that T72's max at approx 625rwhp
i would think the T76 would max at 800ish
T81's - 900+
the GT42 i have i am hoping for 700@18psi
treat the 20b as a 3.8 or 3.9 liter piston engine and you'll find it alot easier to read those compression maps.

look up Red RX7 and someone posted there dyno of a 8psi gt42 53 trim dyno run
it might give you an idea of what you going to see w/ a gt42 or t76 (they are close)
the t72 is about the same size as the greddy t88 I THINK...not sure

the question about room... it a matter of the manifold you get made or hood modifications

Hope my input helped a bit

 

Diesel?

Ever trying running that on the street?
Setting an engine to run at WOT primarily is easier than you think...


-Ted

 

Why? Ted, are you basically saying that a mechanically sequential system is completely impractical for the street? I'm really curious about this mechanical sequential way... An ECU-controlled sequential system is prohibitively expensive. I remember reading one guy on the Supra Forum wanted to have a completely new set of sequential twins fabricated, and he found someone in Sweden I believe that said they'd do it for $20K, simply due to the complexity involved

 

Agreed. I do believe that a dual setup can be better than a single in some instances.

 

Doesn't have to be diesel, some are methanol. The point was not what the motor was but the idea of utilizing a mechanical sequential system. The other thing I can point to for reference is an industrial air compressor system which are staged as well (especially when you get to the twin or more screws running in the 200HP range or more).

Part of how the tractors in particular get up to those kind of huge boost pressures is, just like you've said, through WOT only and not realistic for street use, however, the mechanical system allowing the pressure to build from one compressor to another is what interested me vs. having electrically-controlled solenoids controlling the pressure.

 

http://www.nopistons.com/forums/inde...howtopic=51642

should be good for a 20B and your hp goals , I want $1500 for it.

 

The turbo in my engine bay.!!

 

How can a mechancical trubo charger produce 508psi? I think that number is insanley high, what compression ratio would they use? 1:1? LOL

LOL .. Honestly .. a shaft and blade can NOT produce that much pressure .. not in something as mass produced as a tractor!

I could be wrong and if so .. then great I have leart something new .. but i am very curios and skeptical(sp?)!

 

maybe i'm wrong, but i understood it as a tractor PULL, not an actual tractor pulling something. more like those loud *** vehicles that pull weights across dirt... they've got go have some insane power to pull off what they do.

 

Where did you hear this?

 

Its called compound turbocharging and even 20 years ago they were running manifold pressures of 250 psig.. The blades don't care its just a pressure ratio that is multiplied...Its a way of achieving very high boost pressures while maintiaing compressor efficiency.. Water and methanol are often injected interstage to intercool...
Perkins and cummins both used and some still use it on highway tractors, and power plants.. Some race cars have tried it, a variation on the theme is twin charging, which some mr2/corrolla people do...
Basically the heat of compression of the air is reduced by doing the compression in stages rather than all at once...max

 

Max, can you elaborate on the twin charging ppl do w/ MR2s and Corrollas?

Thanks
~Ramy

 

HKS twin-charger kits.
I believe the 4AGZ were electronically controll clutch on the stock SC's.
HKS stuffs a turbo in series, so the SC takes care of low end boost and the turbo kicks in for top end power.


-Ted