Lag difference btwn the gt28rs and gt2871rs

[youngspeed]

STFA already. Seen quite a number of very solid and educational write ups on lag issues. What I need is a real drivers perspective on the difference between these 2 turbos.

[Doss]

I talked with ATP yesterday and they said the GTRS lags far less than the GT2871R FWIW.

Funny thing is, they even said a GT2871R wouldn't be very much fun in traffic on a daily driver. LOL

[F16HTON]

There is virtually no difference (150 RPMS) between the two...I have driven both.

The 71R has just a little bit more up top, it is not real noticable

[A4ringedONE8T]

Are you referring to the actual 28RS and 2871R turbos? Or the Elims??

Greg, which ones you talking about?

[youngspeed]

If the question was for me, the elims.

[F16HTON]

Elims...

The full GT28-71R is not very laggy with the REVO BT software designed for it.

20 PSI is at 4k RPMS (Gerard runs his at 20PSI only)

[A4ringedONE8T]

I thought the full sized 2871R spooled faster than the 71R elim. Is that correct?

Ive talked with a few guys on here that have the 71R and they say that the lag for the 71R is terrible and its a very inefficient turbo. Not going to point out names, but I was pretty close to buying one to play with for a few months before my other BT project gets here and they all said dont waste the time or money, get the GTRS if anything

[actlsub9]

sorry for my noobness with these Bt's but when you guys are refering to lag, are you taking about what rpm the power comes on, or are you talking about the lag between hitting the pedal and when the engine actually responds??

[traf818]

^ What RPM the power comes on.

[A4ringedONE8T]

Lag being the time after you step on the gas till the turbo spools

EDIT ^^ Traf you beat me to it, guess we were typing at the same time

[toaster]

lol, well those two above posts answer his question...

[B6driver]

thanks for pointing that out

[F16HTON]

Originally posted by A4ringedONE8T
I thought the full sized 2871R spooled faster than the 71R elim. Is that correct?

Ive talked with a few guys on here that have the 71R and they say that the lag for the 71R is terrible and its a very inefficient turbo. Not going to point out names, but I was pretty close to buying one to play with for a few months before my other BT project gets here and they all said dont waste the time or money, get the GTRS if anything

I run the off the shelf Eurocode setup, the only difference being the choice of EBC I have and my upgraded fuel pump .

The dyno plots of my setup and Davids give a little bit of an idea of how they spool, however since there were different dyno operators, they most likely brought the power on differently.




Both of us were running 22 psi

[F16HTON]

Say you are in my car on the freeway cruising in fifth at 2500 RPMs, if you floor it, you will see full boost (22-26psi at 3700 RPMS) the car will feel slower, but it will build boost much more quickly than if you drop it to fourth where you will see full boost at 4200 RPMS.

Gearing is what makes the difference, if you ask any GTRS, 71R, GT28RS or GT28-71R owner if they feel tons of lag and they response will be (not if I keep it in the power band)

It is kinda like a 2 stroke motorcycle, the power band is higher than a four stroke, they both make the same power, but the 2 stroke always feels quicker than the four stroke.

The benefit to the four stroke is there is much more torque down low.

[A4ringedONE8T]

Damn Greg ... which turbo you think is better for my car? GTRS or 71R, this will only be on for maybe 6 months, I got something else coming but Im impatient for the other kit!

[Punktar007]

Originally posted by 400HPA4
I run the off the shelf Eurocode setup, the only difference being the choice of EBC I have and my upgraded fuel pump .

The dyno plots of my setup and Davids give a little bit of an idea of how they spool, however since there were different dyno operators, they most likely brought the power on differently.




Both of us were running 22 psi

Why does smaller GTRS makes more power and torque at redline then bigger 2871?

[F16HTON]

Dyno operator, the dyno I used has a safet setup that does not allow it to go over 100 MPH (for insurance purposes) it is a Subaru Shop and the gearing on them in third gear keeps them under 100.

He had to abort the first pull due to overspeed in my car, this was the second pull and they kept it under.

All three of Charlies pulls had to be aborted as his car was going over 100 as well.

[Punktar007]

Originally posted by 400HPA4
Dyno operator, the dyno I used has a safet setup that does not allow it to go over 100 MPH (for insurance purposes) it is a Subaru Shop and the gearing on them in third gear keeps them under 100.

He had to abort the first pull due to overspeed in my car, this was the second pull and they kept it under.

All three of Charlies pulls had to be aborted as his car was going over 100 as well.

At what rpm do you actualy hit 100mph in 3rd gear?

[Entertainment72]

Originally posted by 400HPA4
Dyno operator, the dyno I used has a safet setup that does not allow it to go over 100 MPH (for insurance purposes) it is a Subaru Shop and the gearing on them in third gear keeps them under 100.

He had to abort the first pull due to overspeed in my car, this was the second pull and they kept it under.

All three of Charlies pulls had to be aborted as his car was going over 100 as well.

How accurate could that be then? What is the top of 3rd gear mph? Could you have made more power?

[F16HTON]

Originally posted by Entertainment72
How accurate could that be then? What is the top of 3rd gear mph? Could you have made more power?

I may have made more power, I am not sure on the MPH...Charlies car was on the dyno first and all three of his pulls were aborted, mine was up second, first pull aborted, second and third were OK.

Everytime I go down to Eurocode the guys at Harman Motove do not feel like dynoing my car (because thay are rich and can afford to turn down $$)

David is getting a Mustang AWD at SEMA next week, soon I will have Unlimited dynos

[Punktar007]

Originally posted by 400HPA4
I may have made more power, I am not sure on the MPH...Charlies car was on the dyno first and all three of his pulls were aborted, mine was up second, first pull aborted, second and third were OK.

Everytime I go down to Eurocode the guys at Harman Motove do not feel like dynoing my car (because thay are rich and can afford to turn down $$)

David is getting a Mustang AWD at SEMA next week, soon I will have Unlimited dynos

Are you 5 or 6 spd?

[F16HTON]

5 speed

[Doss]

I'm not understanding why you would limit a dyno to 100 mph. If that's the case, your car should tap it out every time in 3rd gear no matter what your power level is.

That is of course, if the gearing allows you to go over 100 in 3rd.

When we dyno our Mustangs, we run from 4th gear (1:1) and it'll go past 150 mph. It's weird how things just work different in my three little performance worlds. LOL

[actlsub9]

Originally posted by traf818
^ What RPM the power comes on.

Originally posted by A4ringedONE8T
Lag being the time after you step on the gas till the turbo spools

EDIT ^^ Traf you beat me to it, guess we were typing at the same time

ummm i dont get it, i asked if the lag being mentioned was either what rpm the turbo starts to make real power ( I know with the bigger turbos this comes later in the rpm range) OR if lag was refering to the time between when you push the pedal and the time when the engine actually responds. You guys gave both answers

[traf818]

^
The Lag we are reffering to is what RPM the Turbo Begins to spool. What your talking about is throttle response.

[BranCKY3]

With my 2871r elim, I hit 23psi by 4100 rpm in 2nd / 3rd, same boost level in 4th/5th at 3700rpm. Doesn't bother me one bit.

[actlsub9]

Originally posted by traf818
^
The Lag we are reffering to is what RPM the Turbo Begins to spool. What your talking about is throttle response.

is there a change in throttle response with the BT's as well?

[Punktar007]

Originally posted by Doss
I'm not understanding why you would limit a dyno to 100 mph.

never heard of that too..

[BranCKY3]

Originally posted by actlsub9
is there a change in throttle response with the BT's as well?

If you're at the right RPM, no. Punch it at 4000rpm in any gear and you take off like a rocket. Of course if you hit it at 2000rpm there won't be much of a response, it will be enough to daily drive but don't expect a huge torque spike like a k04.

[traf818]

Originally posted by actlsub9
is there a change in throttle response with the BT's as well?

Nope, but there is with a light weight fly wheel.

[F16HTON]

Originally posted by Doss
I'm not understanding why you would limit a dyno to 100 mph. If that's the case, your car should tap it out every time in 3rd gear no matter what your power level is.

That is of course, if the gearing allows you to go over 100 in 3rd.

When we dyno our Mustangs, we run from 4th gear (1:1) and it'll go past 150 mph. It's weird how things just work different in my three little performance worlds. LOL

I know it is kinda crazy, the shop is a Scooby Performance shop and the owner is really cool. Because of his insurance he had Mustang limit to 100 MPH, he told us it can be reprogrammed if I come back or bring him more Audi's.

Charlie was pretty pissed because he may have broken the B6 record that day.

[mike-2ptzero]

Originally posted by traf818
^
The Lag we are reffering to is what RPM the Turbo Begins to spool. What your talking about is throttle response.

What rpm the turbo begins to spool at is known as Boost threshold.

[youngspeed]

Ok so I take it that there really is no major difference. But the 28 is more suitable for the daily driver. Also, pls correct me if I am wrong, the 28rs runs a faster 1/4 mile then the 71?

[mike-2ptzero]

Originally posted by youngspeed
Ok so I take it that there really is no major difference. But the 28 is more suitable for the daily driver. Also, pls correct me if I am wrong, the 28rs runs a faster 1/4 mile then the 71?

Really hard to say if the 28rs runs faster 1/4 mile then the 71 because the 2 cars that I run (rs and 71r) are setup different I did run both on the same day and they ran nearly exactly the same time but the RS turbo was on its way out.


Here is their setups when both ran 12.8's at SAC raceway

Charlies Avant with the RS
Stock brakes
17" OZ's
BFG Drag Radials
CAI filter with no head light

Gregs with the 71r
Big Brembo brakes
19" wheel setup
Stock Air Box
Head light still in


With both of them setup exactly the same and running the same boost the 71r should just edge out the RS at the top end.

[A4ringedONE8T]

Brembo's ... haha Gregs gonna behead you for that Mike