legacy gtb parallel turbo setup

[tez n u]

Is it true that running parallel setup can cause reliability issues since both turbos are of different sizes and can cause uneven cylinder pressure?? Dont know if its true or not, just something i read up online.

[Koom]

Nope, they\'re unreliable because they\'re unreliable....

The turbos are basically the same size, they both work together in the second stage anyway. Parallel setup would just make the boost threshold higher i.e. they\'ll spool later.

Maintenance and checking the vacuum lines/bov\'s for leaks will help the standard system perform more reliably.

[tez n u]

I dont mind running it in parallel setup as long as its safe for the engine......i like having better fuel economy since its my daily work hack i actually converted it to parallel few hours ago but was worried about reliability issues..

[D-Style]

If you read up of how the TT system works, You run "parallel" when you hit secondary anyway....

[Marky]

If anything it would be "easier" on the car since it\'s off boost a heap more, in theory

For what it\'s worth it got me all of 50k per tank improvement, since it\'s such a slug down low you end up using a lot more pedal or just revving the tits off it more often to make it go somewhere - no different to putting a TD06 on a stock motor I guess

On a BH/BE the turbos themselves are identical, only difference is the exhaust housing is a touch bigger on the secondary (and the secondary is BB core, primary isn\'t)

[nickmcgill]

I still want to try run mine in parallel cause my primary spools too quickly.

[Marky]

put a vf26 exh housing on it, that would slow it slightly

[DacerX]

dont drive it thats alot slower and cheaper

[Joker]

L O L

[ODB]

Doh.

IMHO FWIW if you are running parallel on stock gear you wont be satisfied with performance OR driveability.

If you are spending more money to make it run parallel on upgraded gear so performance is better then its cheaper and still betterer to single turbo.

If you are doing it for economy, give yourself an uppercut and bike to work instead.

[tez n u]

Mines a BG5 if that makes any difference

[nickmcgill]

I\'ve got intake and exhaust mods. Spooks quicker than a stock one.

[tez n u]

The extra bov looking thing near the secondary turbo, i just blocked the vacume house coming off it.....em i ment to tee it to the bov or is it ok being blocked off?

[Marky]

Tee it into main bov or block the outlet of it completely - if you just block the vacuum hose it will get blown open like any bov would

If you have an early bg with twin wastegates then you can block the crossover pipe too which allegedly helps things, makes it a true parallel one bank per Turbo arrangement

Pulses would be a bit out of whack mind you

[tez n u]

its a 98 bg5....does that make any difference compared to the earlier bg5\'s?

[tez n u]

Do 98 model bg5 gtb\'s have similer sized turbos for both primary and secondary? Also do 98 model bg5 gtb\'s have larger turbos compared to bh5\'s?

[Joker]

VF18/19 OEM

similar size afaik, Gen III\'s turbs are just newer

[tez n u]

 Marky said:

Tee it into main bov or block the outlet of it completely - if you just block the vacuum hose it will get blown open like any bov would

If you have an early bg with twin wastegates then you can block the crossover pipe too which allegedly helps things, makes it a true parallel one bank per Turbo arrangement

Pulses would be a bit out of whack mind you

So the little bov thing needs boost pressure to stay shut right? So does that mean i can run any vacume hose with boost pressure to it? Also does running it in parallel prolong the life of the turbos at all?

[Marky]

Err yes but simple option is tee it into bov hose

Second part.... depends how you drive I guess. I found I spent a lot more time at the noisy end of the tacho

[tez n u]

I see so running it in parallel has no real effect on the turbos life compared to running it in sequential..

[Marky]

well

one way, the primary runs 24/7, and the secondary runs only when woken up, so "in a way" the primary is doing more work than the other

in parallel, both turbos are running 24/7 but will see less boost most of the time (if you drive like a normal person) - in parallel you end up always having to be a gear lower to get up that hill / pass that person cause it\'s damn near like driving an n/a

End of the day it won\'t make them "last longer" - thats purely down to maintenance and a touch of luck it seems - and gas usage is more down to your right foot than the psi you run. I can get anything between 350km to 600km a tank depending on the type of use it\'s getting and the difference I got in parallel was hard to measure - took 2 or 3 tanks to go "yes it gets 50k or so more mileage" but it\'s sweet f-a realistically

The one thing I can say is that parallel on the stock gear is a waste of time for a daily driver - you get used to it, but then soon as you put it back to sequential you go "ohhhhhhhh that\'s what I was missing". If you\'re doing it for economy or to preserve the motor just drop it back to wastegate pressure, it\'s genuinely prob better on gas with 7psi and part throttle than foot flat and 0psi trying to labour it up to speed all the time (turbocharging to a degree improves economy). I\'ve done it for the odd long trip or fang round the hills just to make it a bit more linear, but day to day I\'m not a fan - you might like it though, some people prefer it

And it sounds terrible haha