Kurgan

Hey guys. I've been reading around and learning more about the 20B. I have some questions...

I don't understand the sizing of aftermarket turbos on a 20B. I've seen several places recommend a T-88, but is that necessary? Are there better single turbo options for a 20B? Does anyone sell an exhuast manifold for a single turbo on a 20B (I doubt it, but I had to ask)?

Also, they 20B that I'm sizing for would be stock ports for now... so keep that in mind. Does the turbo recommendation change for a standard sized street port in this application, or would it just require swapping the exhaust housing (if even that is required/recommended)?

Greg

I have been told by people that a T-76 (Bigger than the Greddy T88) is equivilent to a to4e on a 3 rotor. I have also seen people use T-66s on the 3 rotor and be ok with it. Being that the stock turbos are the smaller twins any T-series turbos would be an upgrade to the turbo system.With the 3 rotor you have to make sure that you get a bigger exhaust housing so the engine wont choke to death~ I plan on eventually running a Thumper 92 on a 3 rotor engine but you have to realize that my car is a trailor bitch. As far as manifold go you have to talk to crispeed or rice racing about that, I dont think that any company has the 3 rotor manifold is production. Give Unlimited RPS a call at (909) 737-8168 they just built a single turbo 3 rotor with a T-66 and you can find part of the buildup in Import Racer magazine

Greg

I was bored and scanned the magazine article for anyone that wants to see the 3 rotor T66

kamikazeRyan

my thought is 3-rotor with a turbonetics Y2K turbo/ 100 to 150 shot of NOS on a 3rd Gen. That would simply kick!!!

95 RX7
T-78
Over 400RWHP on stk motor

97 Supra TT
02 YZF R6 soon!

13BAce

Greg always comes through!

Evil Aviator

I don't know of anybody who sells a bolt-on 20B turbo manifold, but you can get ready-made 20B exhaust flanges from Racing Beat and Jay-Tech. If you are thinking about a 20B swap, just plan on making EVERYTHING custom. I recommend that you get the car running with the stock turbos (good for 550 hp) first, and then convert to a single later - I would have had my car running at least a year ago had I done this.

IMO a T-66 or T-72 running at 1 bar would be nice for a stock-internal 20B road-race/street car. I figured that the T-66 would run out of 1-bar boost right as the engine ran out of RPM's. If you want more boost, and/or make a high-rpm engine, then you will need a REALLY big turbo, or a multi-turbo setup.

Hey, when you call them, could you ask them HTF they figure 1000 hp with a turbocharger that has a 72 lb/min max flow rate and only 1600ccs worth of injectors? Just from some quick calculations with my trusty Windows calculator (although I have been known to make lots of mistakes), that would mean something like a .43 BSFC @ 10:1 AFR and 450 PSI fuel pressure! Maybe there are a lot of typos in the article, but I don't think that I would want them touching my engine without one heck of an explanation. The engine does look nice and shiny, though.

Hehehe, OK, it's for a sand rail - my buddies and I wondered why the turbo was on backwards. BTW, I considered an electric water pump for my car, too, but it looked like too much of a PITA to set up for street use. Scott still has the electric water pump test-millings somewhere in his garage. OK, one question though - if the vehicle is for competition/off-road use, why in the world did they bother with HP-robbing, emissions-friendly, split ignition timing?

Thanks for the pics, Greg! I was wondering what happend to part II of that article because it was supposed to be in the previous issue.

setzep

My thoughts exactly.

RX-7 GT

oh ****! i just noticed that too...maybe they built everything and in the middle said omfg we did it backwards. its so nice we better make this work

peejay

I was wondering that too... "gee why is the air filter pointing backwards and the turbine outlet pointing forwards?" i notice the wastegate exhaust is pointing backwards, i wonder what's up with that. It LOOKS like it could possibly be flipped to run the same direction as the turbine outlet, or do they have some sort of wrap-around exhaust system? I know there's not much room for an exhaust on a rear-engined car...

BTW that air filter looks like it was taken directly from a later-model GM pickup.

And here's a for you... check the caption for the center-top pic on the second page... "this fuel system can deliver up to 1600cc of fuel per minute" Yeah, maybe per injector... GSL-SEs had more fuel delivery than that!

RX-7 GT

maybe they want to run the exhaust system drag style like just comming out by the wheel? dunno...im confused

Kurgan

most sand rails that I've seen have the engine mounted backwards, in the back, and the ones that I've seen are using VW tranny's for some reason... but I doubt a VW tranny would hold up to the power of that 20B.. scratch that, I know it wouldn't.

Any how, back to the original question... sizing a turbo for a 20B. Does anyone have any dyno's of a 3 rotor with different turbos? Dyno from the stock twins? What does a stock 20B safely rev to? How much boost can a stock 20B hold from a large turbo?

I'm pretty damn close to commiting to the 20B swap, so I'm looking for ANY info anyone has...

Thanks guys.

HWO

The answer to that question is something along the lines of.............. however much boost you need to blow into your engine to make 1500HP which is where you will start to run into E-Shaft breakage problems.

Just like a 13B, if you have enough fuel going in to keep the a/f ratio correct, then your fuel supply is the only thing limiting how much boost you can run.

the size of ya ***** are often the limiting thing in how much boost you run.

Turbo III

I'm actually in the process and have been looking for a single turbo for my 20B for a year now. I have not actually started my motor yet even though the installation is almost finished, and have heard a lot of subjective opinions on this subject with few people having any real knowledge on the subject...not to be negative of course.

With that said, I have spoken with the Hitman out of Aus. and he said on his frankenstein 20B/13B that a T-66 was too small and was choking the motor...keep in mind that he was also hitting 20psi at 2K!

After speaking with Ray at SR many times on this subject, he is now in the process of developing a "street-worthy" 20B single turbo. It should be done with the testing phase around Dec/Jan so call him and keep bothering in order to let him know there is a definitive interest in this project. The cost is supposed to be $3K with the turbo/manifold/wastegate.

Evil Aviator

The web site says it was a 60-1, not a T66, and that it hit 20psi at 2500rpm, not 2000.
http://www.hitman.hm/turbo1.htm

If you look at the 60-1 compressor map, you can see quite clearly that a 20B @ 100% Ev at 20psi boost could in fact hit max boost around 2000-2500rpm, and would start choking itself out of air before it hits 5000rpm. Given the highly-advanced level of mechanical knowledge required to build Hitman's engine, I assume that the 60-1 turbo and the inappropriate 42mm wastegate were only used because they were sitting around the shop. There's nothing wrong with this, really, but it just goes to show that even the best of them don't have a 100% sterling setup, especially in the initial phases.
http://www.turboneticsinc.com/comp_maps/fig9.html

DELTA_Rotary

Someone should look into the HKS 2835 twins. They make crazy HP. There are a few Supras running them making 1000HP at the crank. The Supra guys say they have some lag but I bet a 3 rotor would spool those puppies up fast! The only down side is the price tag 8-10 grand OUCH!!!

HWO

for those that dont know, this guy included, two turbos that would be suitable for a 3L boingers wouldn't flow the exhuast requirements of a 3 rotor.

DELTA_Rotary

Have you seen the size of those 2835 twins? They are huge I'm positive they could handle a decent amount. And if not upgrade to the 3835's they are even bigger. It seems to me if they can support over a 1000 HP they could flow enough.


http://www.suprastore.com/hksgt28twink.html

Check out the link and look at the size and dyno sheet.

HWO

if you go to that page you will see it says "0.50 exhaust a/r, 51.2mm exh.wheel" thats hideous, a 13B would probably start to choke on those, let alone a 20B.

DELTA_Rotary

I didn't say that the turbo would flow crazy amounts. A 20B would choke on a T-66 at higher rpms, but that doesnt mean its a bad turbo. The 2835's would be a good for all around performance. Ok so that A/R isn't great but that is for each turbo! There are 2 of them! If you want to flow mass amounts look into the 3835's.

Kurgan

Twin turbos are out of the equation. I'm only interested in a single setup. But, thanks for the idea...

HWO

A T-66 is a COMPRESSOR WHEEL, these twin turbos you are so hyped up over have 50mm exhuast turbinee wheels, to put it nicely, try flowing 3 rotors, thats 1.5 times the exhuast flow of your 13B, out two holes, each the size of your ******* when you are taking a ****......................

NOW DO YOU GET THE IDEA???????????????????????????

DELTA_Rotary

Yeah your right they wouldn't flow crap. I guess you should just stick to the stock twins on it and make 550HP I mean I'm sure upgraded turbos would make much less than stock.

HWO

the exhuast wheels on the stock twins are around that size, possibly even larger...........

AJC13B

Back in the mid 90s when Matts project was first started, a 60-1 was a big ******* turbo. When the car hit the road, any serious 13B had a 60-1 hanging off the side of it.
From experience, Matts car would hit 20psi in ANY gear by about 3500rpm. Half throttle. The turbo was cactus after 3000kms.

The new turbo Matt has is a monster, no 2 ways about it. When the car gets back on the road with this thing hanging off the side, fire and brimstone may fall upon earth!

Evil Aviator

OK, I'm only seeing 650hp on that dyno chart. What am I missing here? A single T66 setup could do that for half the price.

I'll agree with HWO in that those turbos probably are not sized well for the increased exhaust velocity of the rotary engine, and I'll go one better by saying that the compressors may also have a problem flowing the 133% airflow to a 20B vs. the Supra 3L. This is all speculation on my part, however, as I have not seen a compressor map on these turbos, and I don't know what kind of trim the turbine wheels have (size isn't the only thing that determines flow rate). The thing is, if it's perfectly sized for a Supra, then it's not perfectly sized for a 20B.

Aha, the old "use what everyone else is using without checking out the numbers first" pitfall. Hehehe.

I did this, too, but with my fuel cell. Yeah, I figured that I was good with my 15gal fuel cell - hey, it worked great with the 13B, and that's what everyone else uses. Oh, and did I mention that my 20B car needs to go 90 mi (plus grid time) without refueling, and at a top speed that will require about 550hp? Well, one day while I was sizing fuel injectors for my project... You would think that a pilot would have figured that out a little earlier (duh). Needless to say, my 1Gen has a nice 15gal fuel cell now, and the 20B car is awaiting a slightly larger cell. :p