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The T25 and T28 turbos spool the same, within 500revs. almost no difference. At about 2800rpm. (load dependant).

All of the SR20DET and CA18DET have very similar exhaust housings, 0.63AR T25 flange. Although the T25 has a slightly different dump pipe flange bolt pattern.

A small GT25 turbo is much better than any T28, but I've seen guys use a healthy T28, getting 170kW at the wheels on a CA18DET.

Twin turbo is increasing the points of failure, not worth the effort on a street car, IMHO. It's very hard to justify.

I saw a dodgy import ca18det that had twin turbos in a car magazine. I think they were Cappucino 600cc turbos.

I don't think there was ever factory twin turbo. Not on a Nissan 4 cylinder.

Prove me wrong, and we can all look at the pictures and be amazed.

i guess the question really is,
what does a stock CA hit full boost at?
and what does a t28 CA hit full boost at? (being the obvious turbo upgrade)

if putting a t28 on results in lots of lag, i could see the need for going twin to get extra boost up high but keep low rev boost also

if the t28 spools early then there may be no need to go twin

i think i was told yesterday the t28 has the same exhaust housing as a t25 (maybe got it confused), so it would spool at the same time as stock

then theres the fact it's roller bearing so it may even spool earlier?

but then i dont know when a stock spools up at anyway???

i actually have myself a CA now which basically is in parts so i am going to rebuild it to ensure i have a fresh motor, i will soon be thinking what to do with it exactly, and yeah, im considering the twin turbo route for it aswell, but i guess that depends on the answers to my questions above

Nissan actually made a CA18DETT I've seen pics, I can't remember what it went in but it was the equivilent of the black top sr, except in the CA family. I'm trying to find pics of it.

Cheers
Damo

AFRacer has a good point. My advice would be to fit a correctly sized single turbo as this would be far cheaper and less hassle. Also what car is this in? Would 2 turbos fit in the engine bay? Would the manifold have to be too complex and restricivte too make it worthwhile? Also if your after more perfomance just putting two turbos instead of one won't give you any more horsepower, assuming both turbo setups are matched to the engines characteristics. The two setups may differ slightly in the shape of the power curve but max horse power will be the same.

Having said all that if you have the money and really want to do it i'm sure you could but for me i'd get a well matched single turbo and spend the money that would've been spent on the second turbo and twice the plumbing on some other areas like a big intercooler, headwork, cams, aftermarket comper,ect.

Sure it could be "successful" -- why wouldn't it? Many factory automobiles have used twin turbos. 1200 rallycar even has a successful twin turbo A15.

But the point being made is that a single turbo is 1) also "successful" and is 2) less work and 3) less cost.

I say if you do the work yourself, go for it. It sure sounds better, doesn't it? And it will work. If you are building a show car then any extra cost is not a primary concern so the points made in the previous posts are not important.

the main idea of this was purely for more performance and something different there wouldnt be any problem with the fabrication side of things as my mechanic has fabricated a Twin turbo set up for a supercharged torana from redcliffe, and proved 2 be a success, there are other ways of increasing performance with larger single turbo like hks Gt3037 and pulley set as AFRacer said, which will be another option 2 more hp,
im definelty gona look into it and ask a few people of there opinions and try 2 get as much info as posible before even starting 2 plan anything in the near future,

Personally I think it would be a waste of time and money...definitely unique, but why would you want to do it unless you just have money sittin around to blow. You can get plenty of power out of a properly sized single turbo that bolts up to the original location even for a lot less. If reduced turbo lag and low end grunt is what you're looking for, then go with a lightweight flywheel, underdrive pulleys, and a GT28RS (aka disco potato....I hate that name!). This turbine is said to be one of THE best street turbines for a CA/SR as it has virtually no turbo lag but is still good to pull up to ~350 hp.

Think of how much more work it would be to make a manifold, all the plumbing, the exhaust...gosh I don't even want to think about how much of a pain all that would be. I say just stick to a properly sized single tuned properly and you'll be way happier.

I think the main problem you would have would be generating enough exhaust gas to spin two turbos from a relatively small 1.8 litre engine.But if you used small enough exhaust housings and can rev it hard to generate enough gas to create good boost preassure it would be a very interesting project.I have seen a sr20 with twin TD06 turbos normally seen on gtr's and ive also seen a 2.2 litre honda prelude engine with twin TD04 wrx turbo's so I guess anyhtings possible good luck if you go through with it

There was an old issue of 'Zoom' magazine where a bloke had a twin turbo SR20det in a 120Y, I'll try and find the article and scan it.