question for you all

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pulsarboby

Guest
been thinking about this and would like to see what some of you think:lol:

if you had a standard t28 tubby running say 1.4 boost
then the same car with same mods but fitted with a 2871r running same boost
then same car again but this time fitted with 3071r
which would be the fastest and why???
 
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paz

Active Member
It depends on what you mean by 'fastest'.

From what I've read, the 2871 car would make peak boost earlier - hence accelerating quicker. The 3071 would be laggier than the 2871, and potentially from what I've read recently maybe even laggier than the standard tubby - however that may not be the case.

AFAIK the 3071 would *probably* make more power, but only slightly over the 2871 - as I believe they are both comfortable at that level of boost. I believe the standard tubby would run out of puff at that boost level, so the power would probably flatten out.

Remember I'm a technical retard, so please be gentle :lol:
 
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pulsarboby

Guest
ok yes didnt really explain it that well.
lets say for arguement sake on the 1/4 mile which car do you think will do the quickest time?
 
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paz

Active Member
:lol: No idea :lol:

Personally I'd guess at the 2871 just because you'd hit full boost quicker in each gear and I don't think it would run out of puff.
 
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pulsarboby

Guest
ok thats your guess paz, but even if it did (which it will) run out of puff quicker!
all you would need to do to compensate is change gear sooner, which then would put it right back in the running, thats got you thinking hasnt it:lol:
 
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MarkTurbo

Well-Known Member
pulsarboby said:
lets say for arguement sake on the 1/4 mile which car do you think will do the quickest time?
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3071 would be quickest as it would be making the most power ;-) I reckon the 3071 would do a high 11 against a low 12 from the car with the standard turbo.

I dont think the small amount of extra lag would be an issue on a drag strip!
 
stevepudney

stevepudney

GTiROC CHAIRMAN
Staff member
Personally, having had all those turbo's fitted (not all together obviously) at one stage or another, you can rule out the standard turbo as it's a lag monster and prehistoric compared to the garrett 3071 and the 2871.

I think that out of the 2 remaining choices that the 3071 is slightly better suited to the standard displacement SR20 and certainly on the set up I was running was the more responsive less laggy of the 2, I don't no why but it just was. As it was shown in a thread some time ago I was hitting full boost (granted it was 1.9 bar at the time and not 1.4 ) by just after 3000 rpm.

I don't think there's much in it really, certainly not much in it as far as lag in the lower rpm range is concerned and I'd guess that the 3071 set at 1.4 bar at full tilt would be pulling a little harder than the 2871 would be.

I would say the 3071 c/w .63ar turbine housing would be a faster turbo.............
 
Trondelond

Trondelond

Active Member
I'd guess the 3071, as it delivers more power over a wider range once it's up and running. If you change gears earlier with a 2871, you might end up spending more time changing gears than with a 3071.

If you were running with a lightweight flywheel, maybe there would be a difference in pickup times after letting the clutch go, as a heavier flywheel would help during starts. This would give the 2871 an advantage, as it comes on boost sooner. There's a lot of variables, ifs and buts!
 
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pulsarboby

Guest
but same setup in each car trond! lets say they all have an os giken fitted then that rules out flywheel clutch or anything else.
all cars are running same box too (standard) and all have tmic
 
Trip

Trip

New Member
1bar of boost with a GT2871R is not the same as having 1bar with a GT3071R. The bigger turbo will flow more air (mass) in the engine.


You should also consider the efficiency islands of the turbo at a given boost Vs flow rate. The lower the efficiency the more heat it generates. Hot air is less dense so the "mass" will decrease (but not pressure). Turbo maps are there to help even though i am still green in this field.

I just sold my gt3071r and moving to a 2871r. I am still debating which 2871r to get.. there are about 8 variants.
 
Trondelond

Trondelond

Active Member
pulsarboby said:
but same setup in each car trond! lets say they all have an os giken fitted then that rules out flywheel clutch or anything else.
all cars are running same box too (standard) and all have tmic
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Yes, I am aware that the cars would be identical, I'm just debating whether the hypothetical flywheel has attributes that would be beneficial to one turbo as opposed to the other! Not that I am certain how _much_ it would matter.

But I'm sticking to my 3071 story!

I suspect you have a plethora of turbos available from time to time, so why not try them and log the performances? Or is this just a wind-up because you HAVE tried them?
 
Trondelond

Trondelond

Active Member
Trip said:
You should also consider the efficiency islands of the turbo at a given boost Vs flow rate. The lower the efficiency the more heat it generates. Hot air is less dense so the "mass" will decrease (but not pressure). Turbo maps are there to help even though i am still green in this field.
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I agree here - the said boost of 1.4 bar is probably good on both turbos, but what happens when you drive them both at 1.6 bar? As far as I've gathered on here, this is the optimal pressure for the 3071, and would the 2871 struggle at these levels? I know the standard turbo may have started to produce a bit of warm air at these boost levels.
 
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ChrisS

New Member
I can give you a bit of a drag comparison, between mine on a 3071r and Chris Murtys running a t28 with the 360 i believe. Both boosting to around 1.3bar, forged engines but im on a quaiffe compared to std box. Hardly anything between them. However, chris is running nitrous. Was on 50jets but i think he'd just moved up to 100's. Mine is probably pulling a bit harder at the top end and getting slightly higher terminals. Without the nitrous mine would be way ahead.

The 3071 and 2871 both have much larger compressers than the t28 and will therefore be shifting alot more air for the same level of boost.
 
Trondelond

Trondelond

Active Member
I'm hoping to push 1.6 bar through my 3071 when I get it on, but I'm worried I'll start blowing clamps and hoses. It will be fun while it lasts, no doubt!
 
Fast Guy

Fast Guy

Moderators
Staff member
MarkTurbo said:
3071 would be quickest as it would be making the most power ;-) I reckon the 3071 would do a high 11 against a low 12 from the car with the standard turbo.

I dont think the small amount of extra lag would be an issue on a drag strip!
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I agree except on my car make that mid 11s and high 11s if I could ever get 1.4bar from the standard turbo.:p
 
PobodY

PobodY

Moderators
Staff member
campbellju said:
http://forums.vwvortex.com/zerothread?id=3980360
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That's a really interesting read Jim - I like the way he's overlayed the revs so that you can get a feeling of when it would spool, and when it runs out of puff - it lets you pick a turbo that would give you the right profile for the way you drive; spooling when you want it to, and running out of puff when you'd change gears anyway.

I guess that affects the answer to Boby's question; it all depends on how you drive it as to which one is best for you... but it seems like the bigger frame of the 3071 would win-out in the challenge set by a drag race.
 
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