Upgrade from 16-15PSI stock twins to 16-15PSI big single WORTH?
 

Hi,

My cars performs beautifully the way I want it to. I'm stock twins non seq at 16PSI peak and 14,5-15PSI redline. All proper cooling/fueling/mapping mods according to the tuning level.
I'm only concerned regarding stock twins longevity.

Is it worth upgrading to single turbo (would be T04R, or HX40 super40 or kind of. no modern turbo like EFR8374), and staying at same boost level?

I don't plan on upgrading MAP sensor to allow mode boost because I don't want to stesss the engine over 16PSI.

If you're asking whether you could make more power at the same boost from a different turbo, the answer is yes. Different turbos flow different volumes of air at different efficiencies at different boost levels.

Is it worth it? It depends on how much money you want to spend and how much power you want. What are your goals?

Regarding the final sentence of your post, boost by itself isn't what stresses an engine. The biggest determinant of engine stress is how much power is being produced. The same power could be produced at different boost levels with different setups. Heat plays a big role on stress too of course. Heat has a relationship with boost, but there are always many others contributing factors, such as how efficient the turbo is at that boost, how much exhaust back pressure, intake air temperatures, what A/F ratio, what ignition timing and what fuel you are using.

Just an example of similar power made at different boost pressures.
My full non sequential twins made 316whp at .9 bar
Someone on the forum with a EFR7670 made 331whp at .5 bar

You have a sweet running car that is quicker than most things already on a circuit. Why rip it all out and spend $10,000 or whatever just to upgrade to a larger single?

The twins will be reliable enough. The vacuum lines and check valves are not difficult to update and diagnose and if you car is running as sweet as it is right now then you must have attended to that already.

Thee twins themselves can easily be rebuilt like any other turbo.

I run a similar setup. It rips and I was quicker than a EFR7670 which was running 14 PSI. Not sure why but on the same circuit on the same day my car was hitting higher mph's at the end of the straight-aways on the track so it just tells you how well the twins can do when tuned and with the right supporting mods to manage the heat.

Been there done that..

I had my fd with parallel twins for 2 years. I made 400hp (in the engine not whp) at 15psi and everything was perfect. The only issue was that the oem twins and their iron exhaust Manifold would get too hot in spirited driving or in street racing. It didn't cause me any issues but I hated seeing thiz part of the engine bay this hot and having 900-1000C of exhaust Temps when street racing.

So I went for a single t04b garret old school. Well immediately I saw the difference in exhaust Temps and the new steel Manifold would keep exhaust gazes running faster. So again at 15psi I got 440 hp. The turbo spooling and more importantly the turbo response is night and day in favor of the single. It's just very very responsive now with no turbo lag while the parallel twins had a very slow response of 1-2 secs. Now it responds instantly. Any way I am happier now as I I can feel the car breathing easier. And the engine bay Temps being kept lower (as are my oil and water Temps)

I wouldn't consider going single until something goes wrong with your twins. And yeah $10k is what it's going to cost when all is said and done.

$10k is definitely the high water mark. But if you already have the supporting mods for the twins running 400+hp, then going single should be almost a bolt in affair.

Going from stock to single can quickly get up to $10k before you even unbolt the first thing...

It also depends on how much of it you can actually do yourself so don't forget to factor in labour rates.

Thanks everybody for your answers.