TT_Rex_7

Probably due to space issues. You could prlly still squeeze in equal runners but it would prlly end up being far more complex and up the price. Only thing that would probably be effected is spool up and not by that much compared to equal length.

-Alex

speeddemon7

very sweet setup.

KNONFS

iTrader: (14)

I've been thinking about this for quite some time...

If we were able to run each turbo exhaust seperately from one to the other (they never merge toghter); wouldn't that lower the emissions considerably?

If it works, even a half BP might be possible, and still pass emissions, am I dreaming?

TT_Rex_7

I think your dreaming. You could run 1 exhaust per downpipe but 1) you'd add weight 2)It'd have to be a totally custom exhaust wich = $ and 3) they'd just put the sniffer on each exhaust pipe (like when they test a truck thats dualed out) I don't think its larger turbo(s) that effect emissions, its having to usually remove the air pump that makes you fail. You can always buy an electric air pump from a Corvette or BMW and only have it run during emissions because if you have it running all the time it'll burn up.

-Alex

RX7-2JOCK

I might of misunderstood John when he was explaining it to me a few weeks back...So hopefully he'll chime in and correct my misunderstanding.

KNONFS

iTrader: (14)

Well, down here in MD\VA, they only placed one probe on one of the exhaust on my FC (that's when the idea hit me). I know its not a matter of the turbo, but going half BP is something I would like to try; but from what I've seen is practically impossibe to pass emissions with.

I wouldn't mind buying a kit like this (if they ever made one for the FC, on such affordable price), and do a dual 2.5 custom exhaust, as long as I can pass emissions on a BP engine

TT_Rex_7

If your talking about the flanges he posted about the other day, I'm cutting them as I'm writing this and should have them shipped to him by Monday.

-Alex

zinx

iTrader: (3)

Its pretty obvious by the manifold, isn't it?

RX7-2JOCK

NICE!!

Nathan Kwok

+1. This kit, or any turbo kit for that matter, wouldn't be even remotely legal in CA, but as long as you have an airpump and a cat you should be able to make any setup (with reasonable ports) pass a sniffer. The turbos aren't really doing anything anyway during the smog test, its all about having the proper partial throttle and idle fuel maps in addition to a properly functioning cat.

TT_Rex_7

True, but he lives in VA. If they dont have visual inspections then they won't see the turbos.

-Alex

MrRx

iTrader: (1)

Ahh, This makes me jelous, Mine twin's are still in progress.

Its so hard to find a good mandrel pipe bender and tig welder.

TT_Rex_7

Why not buy some u-bends and so on, cut em up and weld your pieces?!

-Alex

rotaryfreak3

Damn thats cheap for a ball bearing twin turbo setup. :o

KNONFS

iTrader: (14)

But I want a half BP engine, if its a turbo engine, it would have to be a twin turbo in order to keep the exaust seperated

rotarypower101

iTrader: (1)

I don’t think its total emissions that they test is it, I thought it was percent particulate matter/volume that would count, so each exhaust runner if truly divided would have relatively the same emissions.

KNONFS

iTrader: (14)

Thats sucks then

I guess a half BP won't be possible then.

moehler

iTrader: (12)

So... although these look VERY badass (great job! ), what are the benifits of this type of set-up? I'm guessing better spool time? Do you have any idea how the lag is going to be? I would think that a large single getting spooled by both exhaust ports may spool just as quickly as a smaller turbo spooling form approximately one exhaust port.

Jason

iTrader: (5)

Thats the million dollar question. We will be installing it and testing as soon as they show up. The car they are going on will be at the Rotary Revolution for those that are going.

Jason

Kevin T. Wyum

Assuming the same quality and proper design, two singles will have better response (spool) and the same top end flow as a large single turbo. The reason is the larger single has to have a larger wheel that has more mass a larger distance from the point of rotation (shaft). I might jumble the terminology so I'll let someone that's had a physics course more recently than 15 years ago use the appropriate language. The downside to twins are complexity and expense normally.

I have no familiarity with GT series turbos, how do these different turbos compare to Garret T series sizes? Essentially I'm curious where my T04E 60-1's/T3 exhaust sides would fit in.

Trev and I managed to have equal length runners for both so it can be done and as someone else mentioned it is rather important to do so.

Kevin T. Wyum

Mark'sMazda

^but would the less inertia, make up for having two shafts, two turbine wheels, and two compressors?

Kevin T. Wyum

What's to make up for? Needless to say manufacturers haven't gone to twin turbos because they wanted to spend more money and complicate sports cars further. The blunt answer is properly designed a twin application will be superior to a single in every respect that matters for performance except maybe weight, which is not going to be significant.

Mark'sMazda

I understand that bean counters rule the automotive world, I also understand why a seq. twin setup would have faster spool than a large single, but I don’t see how a non-seq. twin setup will surpass a single in every respect relative to performance.

I meant to ask, if the less inertia of two smaller turbos, will actually spool faster, as they have two compressors, two shafts, and two turbine wheels to spin. After doing some research, I answered my own question.

According to Corky Bell;
“Do twin turbos offer any advantages?
Sometimes. An engine with flow capabilites greater than 300cfm (roughly 180cid) can benifit from twin turbos. Two little turbos can slightly cut turbo lag, as opposed to one large turbo, and allow a better balance of low-speed and top-end performance. Over 350cid, twin turbos become a virtual necessity. Do not accept the idea that twin turbos are inherently more powerful, as too many other factors are involved.”

What does a ported 13brew flow cfm wise?
The KSP drag fc seemed to work very well with it’s twin GT3037's.

modrx7

iTrader: (1)

Twin turbos aren't need for cars over 350ci.... Plenty of big block/sm block chevys feen one single pt88 or the like... Yes twins look cooler, but the performance benefits will be about the same... Maybe a bit quicker spool, but that might be about it. Because all they are doing is pushing air and they may push just as much as a bigger turbo or a little less depending on sizing. So why go twins? Well maybe for looks!! Thats about the only reason I see.

Edan

TT_Rex_7

Is that whole post about a 350 or are you saying theres also no advantage of twins on the 13b? If your saying its pointless besides for looks on our cars then I guess we'll find out but I'd have to disagree. Theres more to factor in then this, but from a simplicity point of view, the factory twins have a .63 A/R on the exhaust side, now go find a single with around a 1.26 A/R and I'm sure it wont spool up near as fast as the factory twins ran non-seq. Thats the sole advantage of twins, they spool faster then an equivalent sized single and they still have power up top. There is alot of sb/bb that run single turbos, but theres also alot that run twins so that comment was totally pointless and has nothing to do with with this thread. No real point in going back and forth with each other, everyone just sit back, relax and wait for the results.

-Alex