Fair 'nuff M8, you cant see why, thats fine, neither do I really, but Chesutiko made it perfectly clear that he INTENDED to fit supporting mods for higher boost pressure, and in fact HAD already collected parts for supporting mods to be fitted at a LATER DATE. Yer, as drz400y stated, the cart before the horse but at the end of the engine tuning day, it matters not. Ill say this again, he asked a simple question, in fact, here it is and I quote: He is upgrading TURBOS, NOT boost pressure, NOT injectors, not heads, not the pressure on his teeth from clenching them or the tnsion in his ringpiece, NOTHING, just turbos so it follows that he would stay with stock boost. Upgrading does not automatically imply upping boost. Nothing you say is incorrect nor not relevant, it just wasnt asked for thats all. I use a T66 on my Vg30det and I run stock boost most of the time. So, I dont NEED any supporting mods, bigger injectors and other bollocks because the flow thru my engine is the same as stock! I also dont NEED a valid reson to use the T66 either. It might just happen that I like the sound of it!!!!!! if thats what floats Chesutikos boat then thats his business. Plenty of ricers fit big-arsed turbos and crap for pure bragging rights only. Whats wrong with that? He has every intention of upgrading supporting bits such as injectors and so-on at a LATER DATE so all good. It doesnt matter when he fits his snails! As to whether he would have tuning dramas IF he fitted a pair of RS's. And the simple answer that he got from only myself, Kabir and a slightly roundabout way drz400y was NO, he would NOT have tuning troubles provided the boost pressure remained STOCK. There was NEVER an inference that the BOOST would be UPGRADED as well since the owner was already actively sourcing his hi-po bits! Just wanted to know if hed have a drama and the answerr is NO if boost remains the same. Shit dude, its all there in black and white. Then incredibly, someone suggests that just because the turbos POTENTIALLY flow double (or whatever it was) he would immediately grenade his engine or other such waffle.......... FFS! That is such a load of hysterical bollocks!!!!!!! Think about it for a second. I know I did and painstakingly explained with a supporting everyday analogy as to why the engine tune WILL NOT change at all really. For the last time, STOCK boost is STOCK boost no matter what turbo produced it. You cannot force a positive displacement engine to eat double its CFM of air at the SAME boost pressure no matter what turbo produces it. The WASTEGATE will take care of the boosting pressure issue and the turbo will simply operate a mile out of its efficiency "island" and do very little untill things rev right up! Nuff said newhoo. You either get it or you dont. Next topic!!!! L8r E
Tassuperkart is 100% correct Bigger turbos can porentially create alot more cfm of air moving through the engine, but not at the same boost level as what it is running now unless others changes are made to cams, valves, porting etc. It will create exactly the same cfm of flow to achieve the same boost level(or restriction to flow), the bigger turbo's will do it with less shaft speed is the only difference.
A valid reason for installing the upgraded turbos and not injectors is the same reason I am doing it. I have engine out at the moment and not enough money for the injectors for couple months. Don't need to pull the engine to replace the injectors, But you do for turbos. So i will putt around at no higher than ~3500 rpm and boost set to lowest I can for a month or so until I have the cash I would be doing this anyway to break in the freshly rebuilt engine so really not too much difference..
I'm going to do the same thing ^^, run my new motor in with new highflow turbo's, stock injectors and current tune then chuck in bigger injectors when I have some more doe and re-tune for high boost
This was my thought. If not running high boost, only bigger turbos will not make huge difference in lower rpm range. Probably car will push more air to engine but will be in safe range until proper tune can be obtained with bigger injectors.
Pretty much, while 7psi from a bigger set of turbos = more air then 7psi from a smaller set...it shouldn't really matter as you won't be maxing out the stock fuel system at such low boost.
The maximum ammount of flow is governed by the engine, not the turbos. The wastegate setting defines the maximum volume of air allowed to pass through the turbine by effectively limiting shaft speed. A bigger set of turbos will flow the same amount of air on the same engine at a lower rpm, this just means you will reach the wastegate setting earlier, it still isnt pushing anymore air through. The engine can only pump so much air, it doesn't matter what the turbos are capable of.
7psi is 7psi but I can see the gt28rs with the extra volume of air at that psi still running the engine quite lean on a stock tune.
There won't be any extra volume of air, the 28rs's will just create the same ammount of air flow, hence pressure at much lower shaft speed.
This all goes against what I always used to think... But after reading all this and having a think, only thing I can really think of that might change anything is the larger exhaust housings will cause less back pressure, but other than that the system is the same as before. And aren't 28RS wastegates 15psi minimum?
I see what you are saying ..the wastegates are controlling the psi and the bigger turbos dont need to spin as fast .. but at some point you still need to adjust your air/fuel ratios?
Larger exhaust housings will create less restriction and be able to flow more air to create the same pressure but we are limited by our vlave sizes. That is the hold up with a VG. So you try and jam as much air through it as possible, hence you up the boost. At the same amount of air, no tuning will be required, but abvisously as I said earlier, theres no fun in that is there.
mmm .. that airflow cant be 100% right. if your saying 7psi on stock turbos will flow the same volume of air as gt28rs on 7psi due to waste gate and slower shaft speed . at 14psi its the same thing? just trying to get my head around this 14psi on stock turbos will make just over 210rwkw and gt28rs will make close to 300rwkw. wheres the slower shaft speed here ?
that statement is right but somethings not right here..... do you agree with this below? same boost pressure on a big and a little turbo flow DIFFERENT volumes of air! thats why you make more power at the same boost setting and need more fuel with bigger turbos. just not making sense that throwing gt28rs on a stock setup will flow the same because its compensated by slower shaft speed at same boost setting. I'm off to bed to sleep on it.
This is correct, the turbos will flow different volumes of air at the same PSI no matter what. If it was otherwise why would people bother with upgrading turbo's if they could flow the same air.
What a load of CRAP !!!!! This is a bit of a long read, so if you haven't been following this thread.... I would suggest finding some grass to watch growing OR paint to watch dry :rofl: I've been reading a lot of garbage in here about the engine dictating the amount of air flow If that was correct, an NA would produce EXACTLY the same power as a TT because the 3litre motor dictates the amount of air consumed :bash: Turbos are air pumps, and they jam more air into a (3 litre) TT motor than a (3 litre) NA motor could ever dream about. That's where the potential for greater power exists. The bigger the turbo (air pump) the more air it can flow. The more air flowing the more petrol needed and the more power produced. Now, to go on and say you can just bolt on huge turbos safely, without changing a single thing in the entire system is ludicrous. Let's assume that you wished to attempt such a feat. Theoretically, you could be able to run the setup safely if you could limit the airflow supplied by the large turbos to the scope of the smaller turbo fuel maps and the safe maximum duty cycle of the 370 injectors You would have to constantly monitor a "live" datalogger & datascan, while you're driving the car, to ensure such limits were not exceeded Why the f@ck would you bother ?????????? This whole thread started because someone naively thought they could take a few "shortcuts" in the search for more power. He was bombarded with information (and mis-information) regarding his ill-informed question. The thread then sank into a plethora of "theoretical" (but useless) possibilities which are about as useful as tits on a bull. Theory is all good and well, but I like to think of this forum as a "factual helping hand" from the first hand experience of others, rather than a provider of mythical possibilities. After all, theoretically it's possible to shove a camel through the eye of a needle....... Anyone silly enough to have a crack at it ?
ok so the answer to the OP is no you cant just throw GT28RS and have it run at boost but yes you can with a tune but would be limited to around 10psi before injectors max out.
Where is that 10psi measured? Is that the pressure in the plenum? Edit: The actual Xpsi is irrelavent, just interested to know if point of measurement make a difference in this argument?
