Lookin for advice / suggestions.
Shooting for 450 rwhp with reliability as the key .
Should I go BNR's or an appropriately sized Single TURBO.

The motor is Street Ported, with most supporting mods (stock ignition though)

 

single

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+1

 

I'm kinda leaning in that direction....don't know if the BNR guys mite put up a reasonable argument...GOODFELLAS?

 

he went single

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Tons of threads available on this now that the search function is working.

For that much power, you need to go single (BNR owner here).

 

About 3hrs woth of reading later...SINGLE gets the vote.
Less heat, clean appearance, easier mtce, panty dropping kick!

 

i hate how this subject dies...then gets mentioned in one thread and is now all over the ******* forum again.

do a ****** ******* search please.

 

somebody peepee all over you breakfast

 

Single is more reliable that twins.

 

That is just plain not true. Most stock turbos are good for 80k on average, I see a hell of lot of single turbos needing to be rebuilt long before then. I've also seen a lot of people have boost control problems with singles too. You can say that maintaining them is much simpler than with the twins (especially seq twins), but anything further than that is simply not true.

 

i am one miserable ****.....pretty fucked up since i have a beautiful wife and son at home and a little girl on the way.

 

By reliability I think you mean engine, if that's the case:
450whp <> Reliability period.
When you push an engine (especially Rotary engine) to more than 100% power incease over stock, the reliability is going to dramatically decrease regardless of what kind of turbo you use. As rynberg said, maintenance is easier with a single (2 vac lines) but no matter what you do (ceramic coating, cryo treating, extra cooling etc.) reliability will still suffer.

 

i love the twins.. me im hopeing to get BNRs later in the future

 

Can we then say for 350-450 (rwhp)the answer would be subjective, based on individual definition of "reliable"?
And it would probably explain why this question is repeated ever so often, because a definitive answer cannot be given.(just search and reread the previous threads and tell me i'm wrong)

 

its all in what amount of money you want to put in to the project......i've been reading on single turbo setups and think if you have the money it's the way to go ....
i personally think adding more power to the car (a little cheaper)notsure how much(never went down either road) ...bnr is the way to go.....
i personally am going single in the near near future....

brad

 

Personally I think a single is the way to go. We all know why Mazda did the twins setup. There are singles that can spool very close to the twins, with a much cleaner setup.

Good luck in whichever you choose.

 

I think the key here is in your statement - 'singles that can spool very close to the twins'
The main reason everyone does not go single is that small difference in spoolup. Everyone claims that their single spools up like the twins, yet there are no turbos out there that have gotten close. The people that claim their turbo spools as fast as the twins probably had non. seq. twins for a while before they switched over to a single. A single is going to feel as quick as non. seq. twins but a properly running set of seq. twins are untouchable.
My point is, there are a lot of people that won't accept anything but the quick spool of the twins - 'almost' as quick as the twins just won't cut it. I personally went from a healthy set of seq. twins to an RX6 single and wasn't happy. As quick as the RX6 ball-bearing turbo spools, it is not the instant spool of the twins. I am currently saving for a set of seq. BNRs.
And as far as ease of maintenance goes, there are more parts to the seq. twins however, if you take the time to simplify the system and clean it up, not only will you learn the way it works, but you will be able to find problems much more easily when they occur.

 

There are two ways to look at the spool up issue. You CAN put a single turbo in the place of the twins and have it spool up just as quick, the catch being is its not going to be a gt35 or a rx6 or a t76 its going to be something a bit smaller with a max hp output of 450 not 700. The other thing is Ive come to relize although I love my sequential set-up and it is running very well its to hard to maintain when your really trying to take corners to try and adjust twice to the car having two boost patterns, I cant tell you how many times Ive tryed to enter the freeway in third and had the second turbo come on full throttle right as im entering the corner or in the middle of it and kick the car sideways. then my new arguement is how many people have you raced and beat off of the first turbo? I usually dont make space up to a modified car untill the second turbo kicks and when is that 4500 RPM. Now with a single turbo decent size not trying to make HP records you can easily get full boost by 4000 rpm with a proper set up. Now I dont know about you but with my twins I usually see full boost from the first turbo before 2800-3000 RPM now if i got a single that starts biulding boost around 3000rpm and gives me some boost untill 4000 where I have it all, how much am I really losing on the bottom end. other than the fact you had a number that the boost sat at (10lbs for example) untill the second turbo kicks in which is 4500 you where doing just that, biulding boost until. My guess is that if mazda had the engineering of todays turbos they would have never put a twin set up. The only reason they made it so complicated was they needed small turbo spooling with big turbo output, which is exactly what all the top brand turbo companies are trying to do and it is being done. Well thats just my two sence thanks for reading.

Chris

 

um.....ok?

 

I'm running the stock sequential setup, albeit it is controlled by a PFC tuned by Steve Kan for a smooth power-delivery with (4) 850cc injectors esp. in the transition band.

Even with today's turbos, it's hard to beat a properly setup/engineered set of twins. J

ust look at a Porsche. The current 996 still runs twin turbos, and I've driven one on the track, and they are VERY smooth, with very neglible kick during transition.

:-) neil

 

Where to begin?

No, you would be lucky to get much more than 300 rwhp out of it because it is going to run out of enough air flow at high rpm very quickly. Hell, even an RX-6 peters out at the high end.

You are not driving the car correctly. End of story. The situation you describe has never happened to me in street driving in over 5 years of owning the car. It did happen once to me in an auto-x which put me completely sideways. If this happens to you, it is driver error, not car error.

I'd love see someone flooring a T-78 car from 3k rpm through a corner. You don't think they're going sideways when the boost (finally) kicks in?

That's why you downshift! Who the hell races someone starting below 4000 rpm?

The whole point of the seq twins is to get good "low-end" torque for everyday driving situations, not driving hard or racing.

Well, there are a billion dyno charts all showing the same thing. Usually, a smaller single car has about 50 lb-ft of torque deficit at 3k rpm compared to a seq twin car (worse below that). They usually have even torque by 3.5k rpm. So, for non-racing conditions, you generally have about 50 lb-ft less output. Bigger turbos like a T-78 don't equal the torque output of seq twins until about 4k rpm. So, the answer is, you are giving up a decent chunk of grunt in "normal" driving conditions.

No, it hasn't been done. As evidenced by my paragraph above. It's not done until a single really does have the "low-end" grunt of the seq twins without falling off up top. Since that's a physical impossibility without variable parts, I doubt we will ever see it.

If you want nearly instant spool in a modern car, look at VW. Their 1.8 (now 2.0) engine peaks out at about 2k rpm torque-wise with no lag...but has the power peak at 5k rpm because the turbos rolls off up top. The new Mazdaspeeds do the same damn thing.

 

thanks rynberg, I wasn't sure where to start on that one

 

First let me say thanks for sharing some of your knowlegde. Now let me clarrify some of what I mentioned above since it was pretty vague. Im not against the twins I love them, my arguement is that you can run a single turbo and have very similar results if set-up properlly. A lot of people get the assumption that bigger is better, buy the big turbo, with the big intercooler, and the big piping and what they dont get is all that is is appearance. People normally dont look into the flow rate of there intercooler or turbo , or how long there piping is which all plays factor into responce, efficiancy, and lag.

If you use a turbo to its efficiancy then you shouldnt have a problem with it falling off at the top end. Id have to say a lot of the sequential turbo dyno graphs I have seen fall off top end as well. If you went with something like a gt2876r and you run 18-20 lbs of boost on a properlly tuned set up there is no reason why you cant make 380-420 with quick spool and top end.

As far as my driving hey ive only been driving my 7 for about a month and a half so im still getting use to it but what I meant is if I get on it while coming into the corner hard I can get it loose on the first turbo, and if I dont straighten it out by the time the second turbo kicks it gets really rediculous. What I meant to get accross is yeah its going to kick i can tame that but with a single its a bit more managable since your controlling a constant instead of a variable, and having two turbos which come on at different times is a variable even if you can predict it.

As far as the racing thing, well then why would you need the first turbo anyways? If you donwshifted and your above 4500 rpm your not going to have any lag from a single eighther I was giving a situation in which the twin set-up is better but in a minimal sence, being if you put a twin car up against a single car same weight, same power my bet is on the single since its going to carry a larger power band. Yeah the twins makes the power first, but the single will make the power longer.

Like I said previous Im not arguing for or against twins I love them wish they had more options of them, just giving my opinion that you can biuld a single kit with minimal lag and make good power with the simplicity. I was hard up for a while to work with my machinest to make a custom adapter plate which mounts to the stock manifold and would allow for a gt25r on the front side and a gt28rs mounted reversely with a shared exhaust housing. Hey it still might happen!

Chris

 

As far as the racing thing, well then why would you need the first turbo anyways? If you donwshifted and your above 4500 rpm your not going to have any lag from a single eighther I was giving a situation in which the twin set-up is better but in a minimal sence, being if you put a twin car up against a single car same weight, same power my bet is on the single since its going to carry a larger power band. Yeah the twins makes the power first, but the single will make the power longer.

Like I said previous Im not arguing for or against twins I love them wish they had more options of them, just giving my opinion that you can biuld a single kit with minimal lag and make good power with the simplicity. I was hard up for a while to work with my machinest to make a custom adapter plate which mounts to the stock manifold and would allow for a gt25r on the front side and a gt28rs mounted reversely with a shared exhaust housing. Hey it still might happen!

Chris[/QUOTE]

You know I have been tryin to figure out how to mount two singles into a twin setup as well for a whiel and then I realized...something, your first statement. People say twins for AUto x and crap but realistically If your staying in proper power band by being in the right gear I don't think lag is gunna be a problem. The only real advatage of the twins in my opinion after talking with tons of people and what not is that low end boost...but really whos gunna be in the low end when racing? Sure there are a few of those real sharp hair pins that might make you go down below 4k in 1st gear if EVEN.

The good thing also about the twina is hwy pulling. I dont have to go down from 5th when crusin to hit full boost for fun, it just floors from 3000rpm which is what I usually cruise at and I have full boost and next thing I know ive gone form 70 to 100 in like 2 or 3 seconds...Sure big old single slug aint gunna do that and you'll have to drop it to 4th pfft big deal...if your that lazy then by all means keep the twins, becasue I like doing that too....

But I am def gunna go single sooner or later when I have funds to do it all properly. Plus fuel econ seems better for the single becasue they can cruise at a slightly higher RPM and they still arent boosting and thus using less fuel. Seems a bit better for stop n go too. And really, you think about it 1st gear is pretty damn short if you wot in first gear your gunan get boost real quick! and then your already at full boost in second if you switch at red line or a little bellow.

AH ALSO! YOU HAVE TOPORT THE WASTE GATE when you have done a few damn mods! I am currently in the process of having to do this BS! On a single you just adjust the gate and blamo no boost creep to 20+ psi out of no where! And yes do not forget the god for saken RATS nest of solenoids...They are alll gunna go one at a time or all at once sooner or later!

If your worried about the powerband check out this super sweet site of dynos someone here setup....You can compare powerbands and god form there with what size turbo you want running what kind of AR and what not!
http://71.102.125.165/dyno.php