Real Fiero Tech

In general, what are your opinions on smaller twin turbos vs a large single turbo on a V6? I'm looking for some pros and cons of each setup.

Being that i'm used to the supercharger, I was thinking that a set of small internally gated turbos would give me somewhat similar drivability as I'm used to, with more ability to flow efficiently on the top end. I would think that a turbo on each bank should put me around 425 to the wheels with a fairly nice power curve.

On the other hand, I could run a big single and lose the low end as i'd have a bit more spool time. I should be able to make much more top end power, however. Also, running through the gears, the spool should really be unnoticeable because the shifts will keep me above what the spool rpm would be anyways. I'd probably only notice at low rpm where I would have to downshift where as I may be able to hold the gear with the twins.

I'm just in the early stages of brain storming, but i'm tossing around the idea of two turbos on the 3800. I'm going to be using a different upper intake, either something fully custom, or a modified holden intake. I'm also going to be switching to a stattama turbo cam since they seem to be fairly common in the marketplace.

Modern twin scroll ball bearing turbos will spool up nearly as fast as a pair of small twins and have awesome efficiency. If your turbo is properly sized for your engine displacement and expected power output it will have great response.

I'm thinking of going single turbo on my GTR for this reason. I can either upgrade the twins or go to a single turbo. Less weight with 1 turbo and the response should be the same as my 16 year old singles.

Its also cheaper to buy 1 quality single vs 2 smaller quality turbos.

crzyone wrote: Its also cheaper to buy 1 quality single vs 2 smaller quality turbos.

I disagree.

I think going with twins has the advantage of being cheaper because usually the smaller turbos are used on some stock vehicle..... and rebuilt units can be picked up cheap.

New vs New, you're probably right.

If you were to build it correctly and not cheaply then the single would be cheaper.

2 vw 1.8L turbos would be just about perfect as far as displacement goes.

Two of something used on something cheaper than a Porsche = cheap

Two of something you'd actually want on your car (GT28RS, for instance) = not cheap.

So yeah, quality for quality it's cheaper to go single.
Quality for quality, you get better response from twins.

I say single.

My setup is sized properly and the only time there is lag is when I am not in the right gear for the mph I am doing. Its simple though I just downshift and no lag.

THe 3.8 is torquey enough to have a smidge of lag anyways. Lag isn't a bad thing that everyone likes to make it out to be. Your car still accelerates faster with lag then if the same car didn't have a turbo and no lag. Its just that when the boost finally comes on is when the fun begins so people tend to think that when there is lag then the car is slow but its not.

I would try to go with a ball bearing single if you can afford it. Modern technology has made it much easier to have much broader powerbands even with large single turbos.

FieroX runs a T66 and his spools pretty quick. Just ask him about lag and base your decision on single off that. But honestly I think twins is just too much headache. Especially when the same power and response can be achieved with a good single all with less plumbing and space constraints.

I cant feel when the boost comes in because the 3400 is so torquey, and I am only running a single.

So, given this debate, what would the properly sized single turbo be for a modded 3800.

I'm considering the turbo route as well. I would think a gt35r would be the right size looking at this graph [url]http://www.turbobygarrett.com/turbobyga ... et.htm[url]

Not sure about the a/r though.....