94AWDcoupe

iTrader: (125)

I am one who thinks the twin scroll is just hype. I have yet to see what I feel is good back to back proof that the twin scroll setup is worth the effort. But I am also a perfectionist when it comes to my car. If something new comes out that is good it will be on my car. I recently was considering doing a back to back on my own with a 3071 turbo. But my desire changed last week after running into a old friend of mine that is a savy tuner in the sr20det world. He set the stock block HP record back 5 years ago at 565whp on a gt3040 turbo.

We got to talking about turbos and subject of the 3071 came up. He has tuned the turbo on many cars and loves the turbo for a street car. Good power with fast response. The compressor is well matched to the turbine. He had one car making 380whp at 16psi with it. Very impressive. Just think what hp a 20gtLT makes because that is about as close in size as a turbo can get. So I told him I wanted to try the turbo on my car but was torn on what exhaust housing to set it up on. He flat out with enthusiasm said the best housing was the 63 single scroll. He had a customer who fell into internet hype and set out to improve his 3071 setup by switching from the 63 to the 78 divided housing/manifold. The results were not impressive. The 78 a/r divided housing spooled 400 rpm slower and made less power up top with a slight increase in midrange. very disappointing results to say the least. This is reliable info from a real tech head like myself.

I watch very closely what setups do. I compile the info carefully and study the results. this is one of my older dyno graph comparisons of DSM 4g63 graphs. There was a recent dynograph on here of a 3076 that was reportedly spooling very fast for the turbo its size. it was making 200hp at 4000rpm when normal single scroll setups make around 150hp at that rpm. well if you enter those numbers into my compiled list here they are not very impressive. they just fall into average. The supporter of twin scroll will say the open scroll is making 150 and the twin scroll is making 200 and that is proof. What I see is the 150 was just poorly setup. There are single scrolls that can do 250 if you know what you are doing. There is a 50trim on my table that made 268whp at 4000rpm. he went on to tune that car to 507whp on straight 94 octane.

I am gonna sit this hype out till a real back to back test is done. In my opinion that will be done by taking a really flying 35r setup and adding to the mix a twin scroll exhaust side. results will tell.

Smogrunner

iTrader: (5)

I'm subscribed.

SaOrlando

iTrader: (7)

I am interested in the results myself. Although I doubt I will ever go that large.

More important than this.... can I borrow some money?

Forrest Gump 9

iTrader: (19)

I'm no fan of the twin scroll either, but with bigger turbo (like 37R, 40R, 42R,...) you will see significant spool up time improvement over the traditional single scroll. On the Evo (2.0L) the 30R is a great spool up turbo to start with, so by adding the twin scroll to it you will only see minimal gain from the spool up time. For me, I'm still trying to find the limit of the stocker.

crcain

It amazes me the lack of effort vendors go through to do back to back tests. Sadly I think they know hype and riding their reputation sells product just as well as a true back to back test would.

This is not a dig at anyone in particular... but just a general observation. It all means us Evo owners are left trying to decipher dyno sheet after dyno sheet to try to figure out which parts are the best.

Can't wait for Full-Race to get some of these kits installed in customer cars.

homiusang

iTrader: (2)

Good info and list. I will check back to see the results.
Oh btw, time to put that little chart into Excel

Asmodeus6

iTrader: (7)

I took this same standpoint in the FR 3076 thread. And got pickle dicked around by just about everyone sack riding the twinscroll stuff.

My main b**** was simply cost. Unfathomable cost vs transient benefits.

In the mean time, and lack of concrete testing which my protests were mainly a stunt to recieve... I have gathered my own personal understanding of "the difference". The DSM is now just a 14b'd built motor'd waste of a car. I sold the 3065 as part of buying the evo. And while smaller... it still spools slower than the stock evo turbo. Including recovery between shifts.

Both have a decent tune. And the DSM even has a functioning cyclone intake manifold. And the evo still responds better.

I too am waiting to see the numbers on the t/s stuff.
And I'm not even considering spending a penny on it until I see them.

If more people did this, they would have no choice.

Ted B

iTrader: (6)

I've said this maybe a dozen times before, and I'll say it again for the benefit of those who haven't seen it . . .

Unless or until one has an opportunity to drive a properly equipped, properly tuned TS setup, he will be in the dark to some extent. No amount of posted dyno sheets (not even the dozen or so that Geoff has presented) can replace this type of experience. And where dyno charts are concerned, they don't (typically) show spool time, transient response, or what happens for the remaining 99% of throttle position, which more or less constitutes 90+% of driving time. These things just cannot be relayed through a keyboard or screen, so until one has the opportunity to test a familiar configuration in TS, he'll just have to be patient until he can. There's no way around it.

That's all (from someone with first-hand experience and nothing to sell).

RaNGVR-4

iTrader: (4)

Physics would tell you theres a few reasons a twin scroll would be the better design, and I guarantee you there is a reason twin scrolls are made. Theyre not made for the hype, theyre made because they can be more efficient.

crcain

Ted am I crazy to think that time to full boost and transient response are near directly related? A turbo that reaches full boost at 3k versus 4k is going to exhibit much better transient response correct?

How exactly does a turbo produce better transient response, yet not spool quicker to full boost?

And as many dyno sheets as Geoff posted, not one has clearly illustrated the trade-offs between divided / open for a turbo like GT30 or GT35 in an Evo application. Clearly twin-scroll has it's value, but nobody can definitively say what the trade offs are in the T3/T4 sized turbos yet can they?

We all drive twin scrolls... evo green, standard turbos, etc. So we all know what you are talking about I think... don't we?

BillAce

iTrader: (2)

The flaw in your thinking is that dyno pulls are all done at full throttle unlike almost all driving. Transient response and time to build boost at partial throttleor when throttle is applied are completely different and where the differences are apparent. You just can't see this on a dyno chart.

Ted B

iTrader: (6)

The dyno does not reveal time to rpm, nor does it reveal anything about changes in throttle position and response time. For anything driven between 0-99% throttle position (anything but a dedicated drag car), there is a world of dynamics and transients that aren't represented in a static dyno run.

It is possible to have two cars that give virtually identical dyno charts, yet drive completely differently. I know, I saw this with my own car, and it illustrated (painfully) how limited dynos are in what they reveal. I let several persons drive my car to given them an opportunity to experience the linearity of the TS configuration, and they all commented on it - something not apparent at all from the dyno chart. Ask Sean Ivey about his recent experience, and I'm sure he'll comment similarly.

Asmodeus6

iTrader: (7)

^ That's the noticeable difference between the DSM & the Evo for me then.
That's why I went from s*** eating grin at how well the CIM/14b combo spooled and tipped in compared to other cars. Cams came in on top... car had a great powerband for a d/d. I could push just about every drop out of it if need be and the car made about 300whp. Same power as the evo.

And then I got the evo and driving that didn't seem impressive at all anymore. Same power, feels like double. Power just comes on like a light switch... 1/4, 1/2, WOT all builds power just as fast. Its like having a methed out, crack head, on speed in charge of building boost. The feeling of power is there long before the boost actually is.

Yes?

In truth I find it a little twitchy. I like how it creates the feeling of power under the typical powerband, but at times it can be frustrating too. The uber insta constant boost thing can be irritating when unwanted. Where the DSM the throttle directly correlates to boost. The Evo does not. 1/4, 1/2 throttle all make that needle swing for the fences. Needed or not.

Am I following more correctly now?
I could see where this on a much bigger turbo, might be magnified. And make a much larger turbo feel alot smaller on the street. What we are discussing is true transients of turbo response. Things almost ethereal in nature. As most of it is driver interpretation of power under the curve. But if I'm on the right page now, I could see this being a huge boon to the guy rocking the 37R on a street car. I'm trying to honestly "get it" Ted.

But the cost difference still pushes this into the boutique range of turbo kits.
And opts me out.

I'd like a compromise. A D/S turbine housing that mates to the stock d/s manifold to keep costs down.
And an way to utilize a single WG to further simplify the setup and again, keep costs down.

Lets face it. A 3071/3076 doesn't even need a 44mm wg let alone 2. A GOOD, 38mm will more than cover it. And the tubular stuff isn't practical for street cars. The car has a hole in the hood for christ sake!

Ted B

iTrader: (6)

It's just that with a large turbo, all points on the curve prior to the spool point feel like an empty pit. IMO, this is the biggest drawback to a larger turbo - the range where large changes in throttle position make little difference. That unresponsiveness doesn't make for an especially pleasant driving experience.

With TS, it feels like something is happening in that range. More happens with the same degree of throttle change, with the result being the car feels far more linear, almost like it has a smaller turbo. That's the best way I can describe it. This being the case, even if TS showed NO WOT performance improvement (but the data I've seen to this point indicates that it does), the improvement it makes in part throttle driving is worthwhile to me.

Asmodeus6

iTrader: (7)

Ok we're on the same page then. I just had to try to correlate what I noticed on the smaller turbo's, and then find a reasonable situation where that would be exacerbated and make it worth more to me.

I know what you mean about "the nothing". And can see where this could influence the drivers opinion of the driveability of the car a good bit.

It just needs to get off its pedestal and become standard operating procedure so its costs go down. I could buy a stripped 1g dsm and put it in the 10's for what the FR kit costs. Which is assinine.

There needs to be more hands stirring the pot so to speak. With more options, and different ways of doing it.