2224v

I'v got a Maserati wich has a 2.8 V6 24-valve engine with twinturbo's and twinintercoolers.

Now it's running 0.8 bar standard wich equates to approx.11 psi
but that is 11 psi from two turbo's (one per bank) so the airvolume could still be pretty big even though it's only running 11 psi no?

Just trying to get my head around to it as some upgrades are on the cards

One for you then Chip?

Munch

Phil?

2224v

Oh dear God here we go again....NO not Phil...

Maria.

NO i can 110% vouch that this chap is NOT phil.

It's Czech Mate

Not sure what you're asking but yes it's 11psi per turbo....so if you were to go to a single turbo setup you'd need to run 22psi on the same sized turbo to get back to your starting point

It's Czech Mate

I thought we'd established it as Hooligan?

2224v

No Lee asked if I was Hooligan, we established nothing.

I happen to know Hooligan is long gone btw.

Munch

my powers are weak omighty one....


seems my 'phil rader' is not strong enough....yet

Maria.

You will learn young Jedi..... you will learn.

2224v

Phil's legacy is very much alive I'll grant him that...

But back to my question: basicly confirms what I figured myself then.
I was amazed how powerfull it feels with only 11 psi but it becomes quite obvious once you realise it's infact double the airflow.

I wondr how much boost you could actually run on one of these: the standard turbo's aren't any good over 15 psi but the engine is low comp to the tune of 7.3:1 so should be handle to quite a bit of boost/ignition?

bud-weis

I don't agree with the first part, providing both turbo's are routed into the same inlet tract then 11 psi is pressure of both combined, not each.

but i guess to make your power on a single turbo of the same size then i suppose you'd have to make it work twice as hard! (22psi)

Lee_R21Turbo

iTrader: (1)

I agree with you here totally!!!

Especially as 22psi is a very high pressure figure as standard!!!

C4llyT

Careful, Tom Williams was as sure as you about some German on Migweb, I'm not German

I'd have thought the psi you see is the maximum seen by either turbo, or both combined, dunno for sure though.

It's Czech Mate

if you assume both turbo's run the same psi and go into a common inlet then if the overall boost is 11psi then each turbo will be doing 11psi....

2224v

They both enter the same tract so boost is 11 psi but overal airvolume is double that of comparable singel turbo then

It's Czech Mate

Thats my understanding of it

2224v

I know it is impossible to accuratly predict this BUT:

The car now has around 300 BHP and 450 NM.

I'm planning changing the TB for one wich has both butterfly's opening simultaniously, a K&N replacement panelfilter, a proper freeflow exhaust (the standard bore is tiny!) and the boost upped from 11 psi to 14 psi, along with a live map.

What gains would you guess I could expect?
Educated guessing must be possible for some, Chip where are you when I need you?

Chip

iTrader: (3)

If you want to liken the 11psi of two turbos to one turbo, then its most like 1 turbo twice the size running 11psi.

So 2 t3s running 11psi or 1 gt35 running 11psi will give approx the same sort of throttle response and lag and power etc


The comment about it being the same as 1 turbo the same size running 22psi is an utter nonsense, ignore that totally.

Chip

iTrader: (3)

330-350bhp seems a reasonable estimate, you should pick up at least 10% from the boost increase assuming its not restricted in anyway on the new setting, which it sounds like it wont me, and in fact it sounds like other aspects allowing it to breathe better now will allow it to increase its VE for the same boost if anything.

Chip

iTrader: (3)

You're both ignoring the engine.

The boost you see is as much about how badly the engine is swallowing air as it is about the turbos attempting to flow it.

They will only flow the amount they need to for the actuator to see 11psi and stop them flowing anymore, and the amount of air they need to flow to make that 11psi is determined mainly by how well the engine swallows the air.

2224v

Thank you Chipparoo

330 to 350 BHP and better throttle response sound excellent!

Apperantly the 2-stage TB/butterfly system is what strangles it a bit now and changing that should make it smoother, or so they say.

I wqant to keep the car more or less original due to it's rarity but I feel response ond power would really benefit from better breathing and a PROPER map!

Garage19

Wouldn't work like that. Compressor effeciency and the fact that when you compress air you heat it up means that the comparison you have described above would lead to different power out puts, not the same.

dojj

iTrader: (3)

having had a twin turbo, and having had some experienc from when it wa sin jims car, i hope you can understand the following:

turbo 1 makes 6 psi
turbo 2 makes 6 psi
the inlet manifold sees 6 psi

as measured from the turbos and the inlet (i think jim had 3 turbo gauges in his car at one time to figure it all out )

the smaller turbo's spin up really really quickly and so you have boost available from very low down
the downside is that they run out of puff fairly quickly
on the plus side though, you have a small turbo being powered by one bank, so if you think of it as 2 x renault turbo engines it may give you a fairly comparible size of turbo etc to go with

if you want to have 1 turbo to replace them both, it won't spin up as fast as you will have to run a link pipe from one side to the other

2224v

No chance of converting it to single turbo!

You're wrong in assuming it spins up quickly with boost very low down lol
Starts from 3000 r.p.m. and is boosting properly around 4000 r.p.m.

dojj

iTrader: (3)

what size are the turbo's?
2 x T2's were making max boost at around 1900 rpm and holding all the way to 5600 rpm
the fact that it was making something like 95% of it's max torque at 1500 rpm might have had something to do with it

2224v

No idea but sizewise they look bigger than T2 for sure...more like T3...

Crap exhaust won't help spool up either no?

dojj

iTrader: (3)

fraid not
but you don't want it too big or else you get oil problems

can't explain it technically, but on the inlet side you have the oil seal, but on the exhaust side of the shaft the boost holds the oil in place, so if yuo make it bigger to get rid of the gas faster, the oil starts to leak out
2 inches worth of pipe until it joined the middle and then a 3 inch system all the way until it hit the one box on the rear was all i had and dropping off boxes saw a noticable increase in response and much less lag overall

Chip

iTrader: (3)

Dojj, the seals in the turbo should be capable of holding back the oil even if you have a massive straight through exhaust, if they arent, they are knackered or you have far too much oil pressure

JohnnyB

T3's are a little big for that size engine, unless it revs to 8000 rpm.

2224v

Allready contacted Hayward and Scott for a proper stainless freeflow exhaust...

They LOOK rather more like T3's than T3's but what they actually are I don't know...
Boost does take quite some time to build and then comes in with a bang so...

JohnnyB

what you get with twin turbo's is more volume of air, so the turbo's should hold 11 psi right through the rev range

vroomtshh

Is it a Maserati Bi turbo? If it is then the turbos are the same turbos used on a Daihatsu Charade GTti, and If I wasnt quite drunk just now, I could give you compressor maps and tell you what turbo it is. Its not a T2 though.

And whoever told you they will only run at 15psi is talking nonsense. I have one (albeit new and very slightly modified) thats run 30psi reliably for 3 years

2224v

Could very well be the same turbo, no idea!

Mike R looked the turbo up for me and told me it was not much use above 15-ish psi.
Still, not wanting to make a monster out of anyway, would like to keep it reliable!