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I'm toying around the idea of building a dsm flanged manifold for a rotary. Schedule 10 SS runners, mild steel flange and fully purged with argon.
Being a big fan of MHI turbo's I already have a few laying around.
Reasoning behind this idea is:
1.Mitsubishi turbo's are known for having a good torque hit at low rpm.
2.Also are very reliable even at high boost.
3.Usually somewhat cheap/easy to find and to rebuild.
4.On a dsm a 16g would bust all 4 wheels loose at 30 psi with internal actuator.
5.Can produce more torque than even much larger turbo's, about 500ft/lbs max on dsm.
To take it even further, have gone 10's on real street cars, not tin cans.
I've been searching for anyone using these on rotaries and didn't come up with much other than some posts mentioning them. Mostly parallel twin setups that never take off the ground.
Seems to me it could make for a fun cheap rotary street bruiser, autocrosser, drift type car.
Looking for some opinions on this from the community. Thanks for reading.
I think the value of this turbo you are mentioning just will not translate to a rotary. Turbo is simply to small. I would guess this turbo would be over spinning at very low boost level and would make more heat then power.
use 2 of them and it will work, the JDM tuners had a twin turbo fad in the late 90's/early 2000's and they used TD05/GT3037's. it does look awesome. its a big power setup, so the JDM cars are all 500-750ps, for less power they run something simpler.
Just thought I would mention also that an added beauty of this setup is that you can swap compressor and exhaust wheels, for example, my dsm right now has gtx3076 compressor and lower blade count exhaust wheel for added drive ratio on a unit that looks just like a stock turbo. It pulls very hard out the top without dropping off but loses its real MHI turbo fun on the street, with their fast spool and great torque.
I'm not really talking about building some monster drag car here but just a fun budget rwd rotary car :-)
Yes, it does produce a lot of hot air at 30psi but nothing some e85 and water/meth won't fix if you plan to pull the pin on it. I actually ran one hotpiped like that at that boost, wouldn't recommend it though.
So, you guys don't think it could make for a fun car in a 1st gen rx7 say at 15-20 psi?
Something I've learned over the years is that the people that don't end up over building their cars with huge turbo's are usually the ones that end up having more fun and a lot of times even going faster on a more well balanced setups.
I cant see the point in going for E85 and high boost etc with such a small hair dryer turbo..
E85 is pretty expensive down here anyway.. and I personally would not want to pay the premium for it just to run a small turbo past its efficiency..
(and you would need to upgrade your WHOLE FUEL SYSTEM to run E85 in that old car) all the fuel lines, fuel pump, etc etc will not be suitable for E85. Full on fuel tank forward replacement of everything.
If you go that route your really getting away from the whole "simple, cheap, use what you got, fun car thing" which it appears your trying to do.
IMO use it if you want, but don't expect much. Just because it came off an EVO does not mean its any good for rotary.
Im sure it would make a fun addition to a first gen car though..If I wanted to run that turbo, I would run it, and just be happy running it at 15psi in a responsive setup or whatever.
EDIT; rotarys like low boost pressure and big CFM. 10 psi on one turbo is not 10psi on another.
e.g. that turbo at 30psi will not produce anywhere near as much power as a properly sized turbo at 15psi. It will also be much more dangerous (running the small turbo at 30psi)
To put things in perspective the Evo III TD05-16G has a 55.8mm exhaust wheel major diameter. Stock RX-7 TII turbo has 64mm diameter.
Exhaust housings are the same story. Rotaries produce a lot of exhaust and will choke out on too small of a turbo hotside.
Sure, you can swap around parts on a TD05-16G, but you can swap around parts on the stock TII HT18 because it uses T3/T4 (small shaft) parts.
I had a stock S5 TII turbo built with 74mm P-trim exhaust wheel and 57mm/76mm 60-1 compressor.
I had to go through a lot of work, exhaust manifold/turbo housing porting and using a 60mm external WG because the stock 1.00AR T25 exhaust housing was too small for the exhaust volume generated by the 60-1 compressor.
I maxed that compressor out at 18psi on my engine 380rwhp/300rwtq and wanted more torque ("racing" in parking lots).
I went with the EFR 7670 on a full 2" runner T4 exhaust manifold, dual 44mm wastegates with T4 1.05AR exhaust housing (much bigger than even ported stock manifold/turbo housing). It did have a slightly smaller 70mm exhaust wheel however (and same size compressor).
It was a modern compressor like you are saying that can run high pressure ratio and it spooled insanely fast and made a lot more torque- 420rwhp/420rwtq at 26psi fading to 21psi by 6,500rpm.
Rotaries need big exhaust side. Limit the compressor size if you want low rpm torque over hp.
I think you should strap two of those little buggers on. It would be pretty fucken cool! A turbo for each exhaust port! The integral wastegate will help keep the clutter down.
But as said, too small. If you really want a cheap and cheerful 350 horse, then TII hi-flow.
Parallel twins are laggy because even if you can get enough exhaust energy to spool them you are limited by the surgeline of both turbos added together.
That is, when you look at the compressor map you use half the turbo flow, but the pressure ratio stays the same.
Because of this twin parallel GT28Rs will be slightly laggier than a GT42R and still not match the maximum flow potential.
Parallel twins are laggy because even if you can get enough exhaust energy to spool them you are limited by the surgeline of both turbos added together.
That is, when you look at the compressor map you use half the turbo flow, but the pressure ratio stays the same.
Because of this twin parallel GT28Rs will be slightly laggier than a GT42R and still not match the maximum flow potential.
Mazda developed a turbo rotary in the early 80's, and they went with twin turbos to lower backpressure. (they also went form a PP to a BP for less overlap, and used a half water to air, and half air to air IC), and then it blew up, so they gave it to RB and was last seen in the bonneville FC.
the JDM tuners went through a twin turbo phase in the late 90's, early 2000's, but they fell out of favor. several reasons for that; its expensive, you need 2x of a lot of things. its complex, all that crap needs to fit around the steering column. also drag racing died over there, and your 730ps FC turns out to be useless in a gymkhana, or on the touge. so the context changed.
in the US twin turbos were never really popular at all, a know a few people who have parts, but none of the cars ever seemed to run. and it seems like you can get more power than you know what to do with, with a decent sized single
If I was going to install two air sucking devices it would be for a compound setup, nothing less. :-D. But as mentioned above it's too complicated and too expensive. I like to try and keep things simple usually because that's what works best a lot of times. In dsm community we call it, the minimalistic approach.
I have been away from rotaries for over a decade so naturally a little rusty.
So are you guys saying that in a dsm an evo3 16g can do some real respectable numbers but it won't happen in an rx7? Yes, dsm's also choke them out but it doesn't prevent them from making great power on the street and track.
What about a td06h 20g than?
On a side note, I don't believe the real evo3 16g is comparable to a stock tII turbo. It's not the size of the wheels that make it special but the way it was designed. It was specifically designed to balance the quickest response with max flow and no other turbo even came close until somewhat recent.
So are you guys saying that in a dsm an evo3 16g can do some real respectable numbers but it won't happen in an rx7? Yes, dsm's also choke them out but it doesn't prevent them from making great power on the street and track.
What about a td06h 20g than?
yes. the rotary actually moves air. requires larger turbo.
GReddy sells a TD06 kit, 375hp MAX at the flywheel. the evo turbo is 300MAX on a rotary.
Yes, that is the smallest Mitsubishi turbo people have used on the rotary.
Greddy has a TD06SH 20G-16cm² turbo kit for the 2nd gen and 3rd gen RX-7 13B as their entry level street set-up.
You are doing well to get 350rwhp out of it and you don't get to use the good efficiency at high boost because the compressor only flows like 49lbs/min max, so that will only support 15psi on stock port rotary or 12psi on a streetport rotary.
Rotary is dead opposite of a 4G63.
4G63 has relatively poor head flow, but makes very good power even with very high exhaust manifold pressure. If you want to know what the max power any turbo can do on maxed out boost look at 4G63 dynos.
Rotary has very good port flow, but makes very poor power as exhaust manifold pressure rises. Look at getting 70% of the power a 4G63 makes out of any given turbo compressor while needing a MUCH larger exhaust side (wheel and housing).
If I was going to install two air sucking devices it would be for a compound setup, nothing less. :-D. But as mentioned above it's too complicated and too expensive. I like to try and keep things simple usually because that's what works best a lot of times. In dsm community we call it, the minimalistic approach.
I have been away from rotaries for over a decade so naturally a little rusty.
So are you guys saying that in a dsm an evo3 16g can do some real respectable numbers but it won't happen in an rx7? Yes, dsm's also choke them out but it doesn't prevent them from making great power on the street and track.
What about a td06h 20g than?
On a side note, I don't believe the real evo3 16g is comparable to a stock tII turbo. It's not the size of the wheels that make it special but the way it was designed. It was specifically designed to balance the quickest response with max flow and no other turbo even came close until somewhat recent.
yep. the rotary needs more air to make the same amount of power. So just to be real simplistic, say a turbo moves enough air to make 100hp on a piston car. That will only be enough to feed the rotary to 70hp, max. That's not to say the rotary is at a disadvantage..its capable of moving more air and spooling a bigger turbo...so...it just needs a bigger turbo!
what really matters is flow, as in volume or air moved, and that little turbo does not move much volume..it MAY spool slightly faster due to, you say its "better tech" (debatable but we wont get into that one, lol), but its still limited by the VOLUME of air it can move, which directly limits your power.
you simply cant make more power then the turbo can supply air to support. PSI is not the measure of flow or volume of air moved.
think of it this way, our turbo/engine setups are like running a huge pipe (of water), pressurised to 15psi. It flows a **** load. Total throughput is heaps. Like a damn fire engine hose
Your proposing to run a WAY smaller pipe, think garden hose pipe.
so if we pressurise them both to 15psi (our massive fire fighting 3" dia hose vs your little garden hose) which one is going to flow more water? Add lots more pressure to your little hose...yeah it will flow a little bit more but still not comparable to the big one even at lower psi...pretty much the same applies to turbos
and no you cant just go and increase the size of your intercooler piping to run "a bigger pipe". The turbo is your pipe.
yep. the rotary needs more air to make the same amount of power. So just to be real simplistic, say a turbo moves enough air to make 100hp on a piston car. That will only be enough to feed the rotary to 70hp, max. That's not to say the rotary is at a disadvantage..its capable of moving more air and spooling a bigger turbo...so...it just needs a bigger turbo!
Well, it IS a disadvantage. Rotaries kinda suck for making power in that respect. They're grossly inefficient. That is why practically all racing bodies use a 1.7-1.8 displacement factor when it should be 2.0.
One needs to be realistic about ones' shortcomings in order to do well.
Well, it IS a disadvantage. Rotaries kinda suck for making power in that respect. They're grossly inefficient. That is why practically all racing bodies use a 1.7-1.8 displacement factor when it should be 2.0.
One needs to be realistic about ones' shortcomings in order to do well.
Not disagreeing with the rotary inefficiency, but...
The rotary ability to spool a turbo does seem to offset the larger size required very equitably on a traditional single turbo set-up and perhaps more than equal to piston engine with light EFR exhaust wheels.
Look at single turbo RB26 dynos and single turbo 13B dynos of the same power level and tell me where the difference in powerband is.
Semi p-port/bridgeport rotary probably even has the advantage of 1,000rpms broader torque band over a cammed up RB26.
Well, it IS a disadvantage. Rotaries kinda suck for making power in that respect. They're grossly inefficient. That is why practically all racing bodies use a 1.7-1.8 displacement factor when it should be 2.0.
One needs to be realistic about ones' shortcomings in order to do well.
Yep, we need to use about 30% more fuel along with that 30% more air that's required, to make the same power as the piston engine.
That's obviously a disadvantage.
The rotary is a great pump though. Yes its inefficient at extracting the "most" power of out a "fixed" amount of fuel/air. But the nature of the rotary is it can spool a bigger turbo pretty easily to make up that extra 30% air.
So its disadvantage is only its inefficency and fuel consumption.
Or you could even say that a rotary produces a low HP for the amount of fuel/air it uses at any given power level. Thing is, its easily capable of breathing MORE air...so unless you really care about HP/power vs fuel consumption ratio..then it dosent matter.
The same inefficiencies allow that very sharp forceful exhaust to easily drive a turbo, recuperating lost energy. But engines aren't "air pumps", they are firearms. You can move all the air in the world through an engine and never make power, it is combustion that is important.
I guess this means rotaries are like the H&K G11 of the engine world
Hmm...interesting discussion, thanks to everyone for participating. Forgot just how inefficient rotaries are, I just remember how easy it was to go fast after I bought my first turbo dsm. But somehow there is still something about the rotary that made me come back, I don't feel like I actually ever left them. Just took a long break. :-P
Agreed that engines are like fire arms but with a karate kick to them sometimes. Check out this pic, the most interesting part is not the snapped in half piston rod but the completely untouched crankshaft bearing that still spun freely!
Hmm...interesting discussion, thanks to everyone for participating. Forgot just how inefficient rotaries are, I just remember how easy it was to go fast after I bought my first turbo dsm. But somehow there is still something about the rotary that made me come back, I don't feel like I actually ever left them. Just took a long break. :-P
Agreed that engines are like fire arms but with a karate kick to them sometimes. Check out this pic, the most interesting part is not the snapped in half piston rod but the completely untouched crankshaft bearing that still spun freely!
It's easy to go fast on a rotary as well, just give up on the 16g and put an appropriate sized snail on there
12-06-15, 09:50 AM
