cwgtex

I've been researching a compound turbo setup, and I had a question.

In a setup that re-uses the factory turbo (such as ATS or MPI) with a larger turbo, is the boost response the same as stock? Or does having a larger, laggier turbo somehow make the stock unit spool up faster?

Any insight into this will be helpful, also if anyone has any more useful information on how twins work or suggestions. I want all around performance, quick spool, more horsepower, more fuel economy, and still able to tow. I know, I want it all, but isn't that the point of twins?

Hintz

Your stock turbo over a s474, which most use will not spool as fast as stock, but it will only take around 100-150 more rpm to spool.

The only way youll get faster than stock spooling on twins is to go with ball bearing turbos.

graphitecumnz

In general, a set of twins will spool slightly slower than the top turbo spools as a single.

cwgtex

That's what I would think, since the exhaust has to turn two turbos instead of one. I was asking because an article in the June 09 issue of Diesel World covers an install of the Aurora Plus Compound system (which re-uses the stock turbo), and it says:

"From the drivability aspect, cruising speeds saw boost levels at 5-to-7 psi as opposed to the 1-to-2 psi before the install. The turbo lag of the factory turbo disappeared; when you pushed the throttle, the big Dodge went."

I want twins, and of course I want them for a good price, hence the appeal of a kit like this.

cwgtex

Bump.

What twins should I get? Like I said, I want the best all around set. Fast spool up, big horsepower, and able to tow. And of course looking for a good deal.

graphitecumnz

Maximized Performance

RAMRODD

cwgtex I sent you a PM
I like my ATS twins. I feel that they spool up faster then stock. I know it really cleaned up the smoke from the smarty. When towing Exhaust temps are down a solid 200 but I don't run my boost over 45.

Big Blue24

The ATS twins have a smaller primary turbo and thus lower overall HP potential. Usually smaller primaries spool up faster and thus "get into the game" by force feeding air into the smaller secondary at the expense of higher overall drive pressure.

RAMRODD

The 3000 is larger then the stock turbo. Are you thinking of the 2000 over the 5000?

soulezoo

This is correct. But once the twins start, so many more "air molecules" get supplied which in turn gets you more "go" and seems faster...

I have done a poor job describing that... but the article on the ATS twins description is a total sales job.

I am not knocking the product at all; I have no experience with it at all and am sure it works fine... just saying someone is trying to blow a little sunshine.

graphitecumnz

I'm on my second set of twins and another thing that will fool you is the sound of certain bottom turbos... I had BD towing twins and they screamed even a low boost levels. I'm now running a SuperB/GT4202 and it's a whisper in comparison... I'm always looking at my boost gauges to see if I'm actually making any boost.... the truck 'sounded' faster before but it definitely pulls harder now.