tk5dan

Yea i am considering the BNR's as well. The price is great compared to the M2's. The only thing i worry about is their reliabiltiy. Since the BNR's aren't new turbo housings just larger compressor wheels etc, that mihgt worry me. I believe artguy when he says that the M2's can hit 400+. *cough glassman cough*. Anyways, at what psi do the BNR's hit 400hp compared to the M2's?

Marshall

yeah, in 3rd gear. The 40-70 3rd gear pull was around for people to get an idea if the car was running right. This has no indication whatsoever of a car's true potential. So you pull up next to that 5.0 with a beefy cam and you're cruising at 40 mph, are you going to leave it in 3rd?

While I have no doubt that M2 bb sequentials are very fun around town and feel great, instant spool isn't going to matter nearly as much as a good launch or a *downshift* in a street race. The power they are capable of making definately will though!

maxcooper

The RX6 dyno graphs that were posted are are from my car. I have similar mods to Greg's car, except for a street port and muffled midpipe instead of a high-flow cat (but I do have an N-Tech cat that I might reinstall).

The boost control (my PowerFC/stock solenoids rig) wasn't working very well, so they might not be a great comparison to make. The boost would rise to 15 psi at 5500 or so and then drop below 12 psi at redline. The peak torque was at 5500 RPM or so at 15 psi, and the peak power was at 7100 RPM or so at 12.5 - 13 psi. The boost values are only my guesses since there was no boost logging. But that boost curve is about what it was on the street in 3rd gear or the track (WSIR front straight) in 4th gear. My curves are pretty jaggy up top, too, so I think I'll try some B10EGV plugs where I can set the gap next time.

By extrapolation, my car should make about 400 RWHP at 15 psi, and perhaps 310 RWTQ. That's about +40HP and +30TQ versus Greg's stock-ported and high-flow cat car. From the graphs, it looks like the RX6 is about 500 RPM behind the M2 twins in spool down low.

I've got an AVC-R and a wideband now, so I'll be tuning for 15-17 psi across the board and do some more dyno stuff.

To me, one of the biggest advantages of staying with sequentials like the BNR or M2 is their SMOG-passability. I'll have a much bigger challenge to get through SMOG, either greasing someone else's palms or getting my own hands greasy.

-Max

1FooknTiteFD

way to lay the smack down on those sequential guys max

yeah but the new apex'i kit, and the HKS kits allow you to retain the airpump and still pass smog....theoretically...

single turbos also result in lower water temperatures and lower air intake temperatures. It's easier to work on the car with less crap under the hood and easier to diagnose the car if there are problems with it.

artguy

great mod list rts...fantastic...

however..you are the exception to the rule. my car has ben maintained religiously and I had my share of stock turbo problems..almost everyone I know has had the problems...like i said...90 percent have issues..ten dont.

glassman...he is putting down similar numbers...think about this...right now he is pushing his turbos to the upper limits...he is one of the few guys doing it with success. however the m2 sheet you are comparing to is not pushing that set to its upper limits..gregs dyno run is at the bottom end of the efficiency range for the m2 set.

you can see rts sheet...he has great numbers......and someone on here has put up dyno sheets from their t78 at less than 400hp...but you cant compare that because the t78 is not maxed out and the stock set is on a reliable sense.

that is the extreme...but i think you see my point. rts pushes the limits in an educated fashion..if you do the same with the m2 set you would be at 400hp as advertised.

cheers to that

****...you aint passin smog in ca with that setup...hahah...especially since davis is gov again and the new smog laws will eventually go into effect. unless you do the palm greasin like max mentioned you will be paying some hefty fines.

honestly though...i really love the rx6...It was honestly my first choice.

I am very happy with my decision though...the m2 drivablity in daily life in the city is second to none.

Im not paying fines...Im moving to boston. hehehe


jason


maxcooper...is the max hp on the rx6 not somewhere in the range of 415hp? what is the best numbers posted from an rx-6? tis hard to compare a streetported car to a non streetported car...you are that much higher in power than him but hp diff with a streetport is 20-30 right? and hp diff from a midpipe vs a hiflow could be as much high end right? so basically the difference you are seeing has to do with the modifications to the vehicle and less to do with the turbo...or am i wrong?

****...what were your dyno numbers? 350 something right..but what lb of boost?

j

maxcooper

I don't know that the max power is. It should be in the low to mid 400s at under 20 psi. I know Chuek in Seoul had a dyno on here with over 400 corrected at 15 psi (uncorrected was almost 450). The RX6 seems to be a high boost boost turbo that is too small to flow enough at high boost on a 13B. The compressor map goes to a PR of 4 or so, which is 45 psi, but the right-most loop is lower, perhaps in the 18-22 psi range and reaches out to about what you'd expect the 13B to flow at redline with boost in the high teens. I would guess that 18-19 psi would be the best pressure to run the RX6 to redline before the efficiency drops off a lot. Maybe I'll try for some "dyno queen" numbers, but I am mostly interested in getting some reasonably safe maps to run 15-17 psi all the time. I would expect that to correspond to 400-430 RWHP. Carcrazy has done a very nice job with the tuning of his T04E (fat torque curve and max power at reasonable boost level) and I would like to do the same with mine.

I do think the porting and cat make a significant difference, but I am not sure it explains the whole difference in observed/expected power. I guess we'll just have to keep dyno'ing to find out. I did make more power with less boost (even with the rich and reliable tuning I requested), which seems like it might even be true with a better porting and exhaust system match if the projections are 400RWHP at 18-19 psi with the M2 twins. Get your car to the dyno! Perhaps we could rent some dyno time together and compare once I get my car tuned up for more boost (my wideband just arrived today).

I like the sequential setups, but the transition was always pretty abrupt on my car. Greg's dyno looks very smooth compared to other seqeuntial dynos I have seen. I suspect that the stock primary turbos is already out of its efficiency range by 4500 on modded cars, so perhaps some more primary capacity is also a big help in smoothing the curve. I was looking to be free of the transition hiccup and the single freed me of that problem. It pulls hard and smooth right through there. I also had trouble with the control system in general, and the single has proven itself to be more consistent (once I got a real boost controller). Those are the some of the reasons I went single, but it seems like the upgraded sequentials with a good boost controller may also address those issues for the most part.

-Max

maxcooper

I can't find the chart, but here is a quote from Cheuk in Seoul:

"I made 417 RWHP corrected (443 uncorrected) on a fully built engine at 15 psi on 89 octane fuel with the RX6. I haven't had time to further tune my car but with some better octane fuel and more boost and time more time on the dyno, I think that 450-500 RWHP is easily doable.... "

Here's the thread the quote is from:
https://www.rx7club.com/forum/showth...threadid=24157

Cheuk is running 8.5:1 rotors and what seems like it must be a bigger port (and/or more open exhaust) than me. He was running a PMS computer when he got those numbers and has since switched to a Haltech so tuning should be easier.

I guess we'll find out eventually if the RX6 can hit 450 as more dyno numbers get posted. I am interested in what kind of power you can put down with the M2 twins, too. Hell, I might switch if they are close. It sure would be nice to have less hassles at SMOG time. Let's make it a race! First one to 450 RWHP on an RX6 or M2 twins wins!

-Max

RTS3GEN

Artguy, thanks for the props, I think, as Cam at Pettit does too, that I got the ONE good set of stock turbos.(LOL). I push the car to the limit often, but I really enjoy the feel and response of the twins(upgraded or stock). I have ridden and driven many FD's both single(big) and (small) as well as some hi flow twins, 99's and upgraded and still all around driveablility and response is there. And as a side note, although I am not pushing 400 plus HP, my car still holds it's own or beats many of the single turbo guys around because of one thing. MY CAR STAYS TOGETHER. Every RX I see whether 2nd or 3rd gen with a single end up blowing seals sky high. I like keeping the twins because it keeps my thirst for boost in Check. I learn how to drive the car not just add boost to make it fast. 400 hp at the tires seems to be limiting factor for LONG term reliability with these engines, stock or built. With the kind of reliablity I have maintained I think I have achieved the perfect balance of power, speed and reliability. My motor, just for reference, was built almost 6 years ago by Cam at Pettit and currently has 43,000 HARD miles on it. Many miles of middle of the summerKansas 100 degree track days(usually 6 or 7 car club clinics/drivers schools). And anyone who knows my car and have seen me drive at these events knows that I put her thru the wringer. I treat every lap as though the engine is only going to last till I hit the straight again. At the strip my sig spells out my times here and there are hundreds of time slips on this engine alone(not all in 12's and 11s,but you get the point). Multiple dyno pulls in the mid 350 hp range too. Would I like more power? YESSIR, but when I get to that point I will not put unwanton demands on the car to continue to perform in this flawless fashion. With added power comes added risk, I think too many people become greedy for "supra like" power from their motors/turbos and expect that reliablilty when they achieve it. Sorry, not going to happen. I think, imo, the twins, upgraded or even stock perform well and can really make the 3rd gen a contender in all arena's, it just hinges on one's ability to not get greedy, make the rest of the car do the performing, ie learn how to drive it, and she will NOT dissapoint!
Art

PS. Sorry for the rant.
(dons flame suit)

ptrhahn

iTrader: (9)

Maxcooper & Artguy:
If you guys are local to each other and meet to dyno, you ought to take te time to do a few rolling races.

I don't drag race (at a track) and I don't know about you but when I DO race someone, its generally a highway roll (2nd thru 3rd, or 3rd thru 4th gears). I also know that IF i loose to a Z06 or other high-torque, large dispacement car, its in that first split second that the other car "jumps" ahead by a car or two because of the torque difference... after that i might be even or faster, but i'm behind, plain and simple. In the real world, you can't always be right in the sweet-spot RPM-wise, and the extra "punch" and torque <possibly> provided by the M2 twins might outweigh peak HP on the road. I couldn't car less about the number i can put at the bottom of my sig., i want to smoke people on the highway.

I believe this is the same theory JimLab is using while building his V8 RX for precisely this application... and I bet his car will be much faster <from a roll> than any single-T RX making the "same" 600 peak hp (if it ever rolls under it own power again?sorry Jim!).

Simply comparing peak hp to peak hp isn't the whole story. I've run a friend's 825 RWHP T66 Supra... The longer we ran, the worse i got beat, but in short blasts... i was right there w/ less than "half" the horsepower.

I'm still willing to concede that a small BB single Is a better deal... So Max/Jason... Why not run 'em and let us all know!

matty

great thread guys....
For what it is worth....I have to say that i am sticking with the stockers. The turbos spool instantaneously with an open exhaust and I murder just about anything at 12psi with all the boltons...for the strip running 15 psi is not going to shorten the life of the turbos. ...
If the time comes that my turbos are shot i am just gonna go withsomething big. I cant see spending $3k for 20 rwhp.

ptrhahn

iTrader: (9)

i think the point that Artguy and other might be trying to make though is that just looking at a RWHP number to assess performance or a cars speed compared to others is like just looking at a "G" number to assess handling. There are rustangs that can pull nearly a G, do they handle like a near-1G RX7? Nope. Just going big and getting a big peak number won't necessarily make your car faster than another... unless you race on the internet.

Jim Calandrella

Artguy, when you move to Boston, let me know. I could always use a fellow enforcer.
Seriously, this is one of the most beneficial discussions i've seen to this point on the forum. There just seems to be no easy way out. I guess for me, the ultimate would be to have the simplicity of a single, with minimal lag, producing near 400 rwhp #'s on the occasional(ok, alittle more than occasional ) episode, all while passing emissions. It's alot, maybe too much to ask. The M2's seem to be living up to their reputation though. I mean, how much do you truly end up giving up to a single on a street race? The singles don't seem to make their power( with the exception of the RX6) until really high in the rpm's. Someone stated earlier that they held their own until 6000 rpm. What happens then? Does the single just rocket away? And for how long before they run out of rpm's?
It seems like a well balanced sequencial car can hold it's own through quite a bit of the powerband, and even beat some of them.
I still think that if you can get away a small single(emissions wise), it's kind of the best of both worlds. The M2's look to be a formidable balance, without having to fab too much. There should definately be a race hooked up though. Single against sequencial. That would be the most educational test.
Of course, RTS3DGEN is totally right. We're all more greedy than we should be for power. If you want the car to run everyday, he is most definately on the right track. The truth be known though, I have some friends with intelligently modded 7's, and they are still breaking stuff as well as the occaisional blow up. I'm thinking that all you can do is be smart about how you mod it, and hope for the best. I hope that's not the case though.

artguy

jim...if the posted dyno charts on the m2 set were on a ported motor with a mid pipe you would see that they should do better higher up in the rpm band.

but yes...once a single gets moving..its MOVIN...Im sure ***** car screams once it hits 4k rpms. the m2 set being sequential just has a different balance. when going with turbo upgrades its all about trade offs....want huge power, say goodbye to low end...want great spoolup, say goodbye to total hp...the m2 set is not a single turbo...but thats why I like it...its not a single turbo.

j

matty

i just havent seen data that shows they are significantly better then the stock twins.atleast not $3000 worth of being better

Jim Calandrella

Artguy, you are totally right. It's all about trade offs. I have to tell you, i'm sort of leaning towards M2's as of now. I intend to get some feedback on the BNR's as well. I was very close to buying some M2's a couple of months ago, but bought a daily driver instead. The more I hear, the more I tend to think I was going in the right direction for me. I love big power, but i'm also very impatient. I don't know how much lag I could deal with.
Matty, it seems that the people that are running the stockers are having to run them really hard, maybe too hard. The people that are running the M2's, are doing it with less wear on the turbos themselves. Basically, more efficiently(less boost). If they dissipate heat like people say, they may be worth the money.

rynberg

Several people in this thread keep harping on this point. He didn't buy them as an upgrade. He bought them because he needed new turbos. As an upgrade, I don't think anyone is going to seriously argue their value. But as a turbo replacement? Since they cost about the same as 99-spec twins, I don't see the problem.

Also, I think too many of you are in the Supra camp as far as numbers go. Who the **** cares if the car makes 500 rwhp from 6.5k-7.5k if it doesn't make any power below 4k? It may be fast on the highway but I doubt it's fun to drive. Which is why Artguy and others have stuck with the twins.

There was a T-78 dyno plot in the single turbo forum last week. With only a downpipe and cat-back at 10 psi, I made 50 ft-lbs more torque at 3000 rpm than the T-78. In fact, the T-78 did not equal my torque until 4000 rpm! How fun is that in normal, everyday driving?

matty

umm...how cheap would it be to buy used stock twins...and they are abundant.
i know people with over 100k miles on the stock twins

artguy

rynberg is right....

for me it was time for new turbos....i could go jspec, pettit, m2, or rx6

I was very concerned about smog and gave up on the rx6 dream...

I then spoke with pettit and they flat out told me that their turbo upgrade would not give me the kind of "upgrade" that I was seeking. Matter of fact their exact words were "if you want to get some more power out of the twins then you should go with the m2 set" they said their turbos were more efficient..but not to the point where I would really notice that big of a difference.

the jspecs...new turbos were tempting...however I lost some low end when I did my streetport and was itching BADLY to get that back. I was tired of being beat off the line and having to catch up. I wanted the jump...if ya know what I mean. I was confident that my streetport and open system would keep my pulling up high. (I never had any complaints about my cars performance up high in the rpm band as the streetport just pulls and pulls and pulls)

my only option at that point...to fill my needs as a driver...was to go with the m2 set.

some of you have different driving needs...if you are running 1/4 mile than this set may not be for you...if you are autoxing then maybe it is...if you are in the city then maybe its a good match...if you are living near lots of open road then perhaps a t78 would be what you need to blast off into 150mph in no time flat....ya gotta ask what it is that you want. someone mentioned that it was not just about the big hp number up top...its not...its about how you want the car balanced out over all. if you dont care about low end at all..then dont get the m2 set....Im the opposite...the low end is where I have the most fun.


j

matty

but my question is why not get a used set of twins..whats the maket value a few hundred $$

artguy

matty....used turbos are a waste of money...and a waste of labor time. you would be better off not spending the 5-700 dollars on a used set and instead going with the bnr basic rebuild for the same price.

good used turbos are not abundant...Ive looked at plenty of sets...four from forum members the last time around and all were leaky as hell.

there is only a small handful of turbo builders who are capable of rebuilding the stock hitachi set properly (for example my turbo city rebuilds lasted less than one day and then pissed oil all over the shop floor) I think BNR, Rotary Reliability and Racing, and Pettit are the only ones that are getting decent sets out to my knowledge.

good luck...

j

btw...I bet I can count the number of guys on the forum that have over 90k on stock twins...finding guys with failed stock sets well under 80k is more to the norm...not the exception, like your pals with 100k on them.

matty

ok....thanks for sharing your experiences

matty

well i dont knopw about that..there was a thread going alittle while ago about miles on the stock twins....several people had over 100k...

artguy

i did try rebuilt turbos...TWICE...haha....both sets failed within months of picking them up. I was running about 12.5lbs of boost on them at the time as well.

both turbo city and Performance Techniques (the weasels who own the domain turbonetics.com trying to snake turbonetics customers) let me down. No warrantee was given even though they promised there would be. I was out 3000 dollars in parts and labor as well as two months down time dealing with the junk.

that is why I was willing to spend the money for quality parts...its not that I didnt try being a cheap bastard..its just that I found out that you cant be cheap when it comes to these cars...either do it right or let it sit in the garage until you can. there is no other way in my mind.

j


max...Im not racing you to that number...hahah my dough would be on your set. but it would be huge to see if it was possible.

ptrhahn

iTrader: (9)

You think you're going to make 360 rwhp with used '93 turbos on a stock motor, no midpipe, and no race gas? More than once?

DarkKnight

This is a really great thread. I really got a lot of great information. I like Artguy's reasons for staying with twins, I have often read about this and debated it in my head a lot. So I think for the future, I will up the boost on my stock twins then try the m2's if/when the stocks fail. Of course this whole thing is academic for about a year or so, I am saving money to get a new ECU, FMIC, radiator, hi flow cat, blah blah blah and do everything at once....