Turbo sigma

[Paydirt]

I had 2 sigmas turbos in my time, one standard, and the other a 2.6 after market job. The bottom end on the 2.6 was standard and held together well. Then again I was using a decompression plate and only running 11psi through it, on a smallish IHI turbo. Gearboxes are your problem, you'll need to use the Jap box, and hence find a block which will suit, as they don't have a removeable bellhousing.

No question about fuel, injection is the only way to go. I had a draw through setup on my 2.6 and i use to pay through the nose. Economy was a non existint word.

VG30 turbo will only be good for 14 psi, cause of the ceramic wheel. And if you indeed are drifting it, and will be sitting on the limit the whole time, I can't see if being a good idea. Just remember sigmas used an external gate too.

[Nufie]

ok would a rota 13b turbo suit?
with ahig flow?

[Zac]

A vg30 turbo with such small exhaust housing and someone pushing to get 200rwkw from it, shaft speed would be through the roof and like Paydirt said, it would surely quickly fail.

[Galantman]

The sigma turbo manifold is NOT a std t3 exhaust flange, its a t04 pattern, but there is more than enough meat in the maifold to drill and tap to suit a conventional t3 pattern ( i have done this).

my main suggestion is a Fully Balanced bottom end and removal of the balance shafts.
otherwise they are a solid motor.
keep the revs down to 6500 if with std valve springs, and for bottom end life 7k.

i ran my 2lt to 7k with no issues. i dont think the 2.6 will get there as easy due to the heavier pistons and the longer stoke will put Drastically more load on the bearings.
the conrods shouldnt have any issues holding together up to 7k. but its your choice of how much extra wear your willing to live with.

[Nufie]

So with the magna injection i wil have to get the throtle bodie changed to the other side ?
And what injectors would you guys sugest ?

[THE ASH]

yes, you'll need the TB put on the other side.

VR4 440cc injectors as a minimum or 13BT 550s if you can get them. the bigger the better (within reason), you'll need aftermarket management anyway

[Nufie]

sweet as i have a microtech handy so thats not a drama

[mutlley]

sweet as i have a microtech handy so thats not a drama

Should have gone for haltech or motec etc, for tuneability.

[Nufie]

each to there own im not fased ither way

[Captiva Fan]

Unless it's a 'budget buildup' & you don't really care about blowing an engine, it's probably worth keeping an eye on exhaust gas temps & the like, if you're using a cheap-and-nasty ECU.

[timtx5]

Ash - If its simons old r31 you are talking about, it was an S4 turbo which is apparently smaller. It was still a very laggy bastard, like all rb20's are though.

[THE ASH]

Ahh, my mistake.

Regarding the ECU - if it's an MT8 or later, I'm sure it would be fine. The tuner has more bearing anyway most of the time

[Nufie]

true rb20 turbos arnt laggy they actually run out of puff my mate had one on his sigma and it ran out of legs an spooled at about 1600rpm full boost around 2500rpm so a high flow s5 turbo will be the way to go on a sigma engine ?
some one was telling me that the vg30 turbo or the gtir turbo would be a better way to what are you opions?

[timtx5]

Nufie - Yeah stock turbos arent too bad on a stock rb20, but once something bigger goes on you notice the lack of torque, I remember driving it and having to drop it back a gear to get up slight hills on the highway at 110km/h. Thats not really relevant to what you want to do.

Im guessing vg30 would be better, these are all still budget options though and some of the new stuff is better but you get what you pay for in a lot of cases. Gti-r turbo isnt too bad on a stock 2 litre, thats what the R31 with the big turbo got replaced by in the case of my brother.

[Nufie]

ok i dont think that really healpd me as im running a sigma engine lol but thanx anyway has anyone else got any sugestions ?