Low boost performance.

[Trondelond]

Gentlemen,

I'm considering a turbo upgrade, and we all know that the 3071 is the turbo of choice at the moment. However - due to rules and regulations here, it's not only illegal to up the power on an engine without proper permission, if the car has been in the country for less than ten years, there's also a tax for increasing the power. Roughly £100 per horsepower. Not bad.

So - if I'm going to upgrade, and someone decides they want to check my car out, I'd like it to perform normally at the original powerfigures.
In conclusion - if I go for a 3071, what boost would I have to run to achieve OE performance? And how will the turbo perform at these boost levels?

 

[carlengerer]

Just dont let it boost at all, Im dont think any ebc can do that, as in boost less than the standard level, but if you get a actuator thats weaker than OEM then you could restrict the power a fair bit. a aftermarket ECU hidden somewhere with a rpm limit will help too.

 

[Trondelond]

Yes, that would be an option, but what happens with emissions when the map is set up for the turbo generating boost at certain rpms?
I've got a powerfc, and I find myself driving at 0.8bar a lot on a daily basis with the OE turbo, as I've no need for the power in town.

Maybe a 3071 at 0.5 bar would be the way to go then.

 

[nex]

You will get the same power from 0.8 bar regardless of the size of the turbo. Just make sure that you have stock boost and fueling when the time comes for inspecting, just get a standard ecu and revert to stock boost, job done i'd have thought?

 

[Trondelond]

You will get the same power from 0.8 bar regardless of the size of the turbo. Just make sure that you have stock boost and fueling when the time comes for inspecting, just get a standard ecu and revert to stock boost, job done i'd have thought?

Is that a can of worms I see? IIRC Odin's car was quite a bit over the 300hp mark you get from 1 bar with the OE turbo.

 

[EssexAaron]

You will get the same power from 0.8 bar regardless of the size of the turbo. Just make sure that you have stock boost and fueling when the time comes for inspecting, just get a standard ecu and revert to stock boost, job done i'd have thought?

that aint right as a bigger turbo will supply more air for the same boost:doh:

 

[warringtonjack]

You will get the same power from 0.8 bar regardless of the size of the turbo.

:doh:

Damn, so there really is no benefit in getting a bigger turbo after all! May as well throw my 3076R out then. :lol: :lol: :lol:

 

[nex]

I just though that the amount or air in the cylinders would be the same at 0.8 bar regardless, as volume is related to pressure and what not.

Obviosuly a bigger turbo has advantages in its ability to reach higher pressure levels and flow more air per spin on the compressor wheel and can maintain that pressure level easier and more important flow more air at the higher RPMS, but as the amount of air entering the engine per stroke is based on the pressure in the system (ie. the boost) the volume of air would be the same, thus so would power.

Arron Ias only thinking about it from a physics side of things, if im wrong then fair do's

 

[Trondelond]

This is why I hate turbos. Too many variables.

But - back to topic - I'm _guessing_ the 3071 would run just fine at (for example) 0.5bar, it just won't be very much fun?

 

[John]

This is why I hate turbos. Too many variables.

But - back to topic - I'm _guessing_ the 3071 would run just fine at (for example) 0.5bar, it just won't be very much fun?

Yeah it would run but it essentially would be boosting on actuator pressure to achieve that sorta figure, so would seem very lothargic

 

[Trondelond]

Thanks, perhaps the gt28rs would be better suited if I want to use "normal" boost levels as well. The car is plenty quick at 1.25bar with the OE turbo, the 3071 must be pretty hairy.

 

[John]

Thanks, perhaps the gt28rs would be better suited if I want to use "normal" boost levels as well. The car is plenty quick at 1.25bar with the OE turbo, the 3071 must be pretty hairy.

Hehe your running near enough what im running on the stock turbo then, a bigger turbo is on my list of upgrades aswell however I wont be going near that for a while as bigger turbo = big cost as alot of other things need to be uprated at the same time.

 

[Trondelond]

Hehe your running near enough what im running on the stock turbo then, a bigger turbo is on my list of upgrades aswell however I wont be going near that for a while as bigger turbo = big cost as alot of other things need to be uprated at the same time.

Well, a bigger turbo doesn't HAVE to mean boosting it to it's very edge, or needing uprated internals, I'd just like one that puts out a liiiittle more power without pushing it to the edge of disintegration. At least for now.

 

[warringtonjack]

You dont really need a bigger turbo then, you should be looking for the quickest spooling turbo you can find that'll keep you around standard(ish) power. The disco spud maybe the right one!

 

[Trondelond]

You dont really need a bigger turbo then, you should be looking for the quickest spooling turbo you can find that'll keep you around standard(ish) power. The disco spud maybe the right one!

I'm getting to that conclusion as well. It's just a shame (if I've read it correctly) that I'll need to do as many mods as if I was fitting a bigger item. On the other hand - should I decide to go bigger later on, It'll be a lot easier.

I'm just a little nervous about the OE one as it's done about 54K now, so I should swap it.

 

[davey red.r]

that aint right as a bigger turbo will supply more air for the same boost:doh:

spot on.

 

[davey red.r]

trond its easy mate, pack your case and leave aha land behind,
come here stick your 3071 on and whack the boost up:lol: 8)


morten harket

 

[Trondelond]

I've actually considered taking the girl to england, if I once wanted a quaife. It would be cheaper and more fun to go get it myself. But - I think LHD would be an interesting sight over there. I don't dare think about the roundabouts..

 

[nex]

Quote:
Originally Posted by EssexAaron
that aint right as a bigger turbo will supply more air for the same boost:doh:


spot on.

I wouldn’t normally care to argue the toss, but quiet simply.......I don’t think your correct in what you saying

Air flow is directly proportional to volume of its conduit/container (your intercooler and pipe work) and the pressure contained in that conduit (again you intercooler and pipe work). The only way to supply more air at the same boost therefore is to increase the diameter/volume of the pipe work feeding into your intake, no simply adding a bigger turbo.

Obviously a small turbo would have to work twice as hard to fill a larger pipework to 0.8 bar than a smaller turbo would, urgo - the advantage of a bigger turbo. However though the cylinder capacity doesn’t really change so 0.8 bar in a piston - cylinder is the same regardless of turbo size, just a smaller turbo might struggle to fill the engine to that pressure at high revs as it cant "flow" or "compress" enough air.

I think its wrong to assumptions that a bigger turbo is "better" because its "bigger" and "will supply more air, with no regard for the phsyics involved.

If im wrong, please post otherwise as we're all learning new things all the time, everyday! its just my thoughts on how it all works :-D

 

[Fusion Ed]

Nex your not very clear. The difference with larger turbos is they are more efficient. The output air is cooler thus more dense, and contains more oxygen to get more power, also typically they produce less back pressure on the exhaust side of the engine so free up more power there.

Turbo size makes a big difference to power at X boost. Rob (odins) pulsar shows this by making 400bhp @ 1 bar boost. Standard T28 would be around 300 odd give or take.