Group A Turbos

[BNR]

Hey

Has anyone heard of Group A turbos out of a R32 GTR ? They are ment to be bigger and support 350HP ??

Anyone know of them ??

Thanks

[Sydneykid]

Yep there was a Group A turbo from Garrett via Nissan for the R32GTR.

[rev210]

They have a 0.6 front and 0.64 rear AR, also called lemans turbo's.

[sav man]

UAS used to sell them didn't they?

[slow13dude]

So Group A and N1 turbos aren't the same thing?

[djr81]

So Group A and N1 turbos aren't the same thing?

No, see the maps. There is a big difference.

Having said that the A/R ratios for both the compressor & turbine housings are the same as for the larger of the N1 turbos, ie 0.6 & 0.64.

I have never seen maps for he two different N1 compressor arrangements, ie 0.42 & 0.6 A/R. So I can't be 100% sure as to which compressor set up the map is for - although being an R33 N1 it is probably 0.42.

Is there anyone with any maps for any of the common Skyline turbos? If so please post em.

[BNR]

What would be better, GT2035's or the Group A turbos.

Im not sure what the graph means ! How much do these turbos cost usually secondhand and what boost can they run ?

[djr81]

Im not sure what the graph means ! How much do these turbos cost usually secondhand and what boost can they run ?

Numbes vary, but 10lb/min of airflow gives approx 100hp at the flywheel. The pressure ratio is pretty self explanatory.

For costings, take a look at the for sale section & any number of the vendors on the site.

[fsmout]

Hi, i have a set of group A's, i thought they were the same as N1's, but would be great if someone can correct me. Mine are quite laggy, not hitting useable until 3900ish, and they really start going after 4.

i have dynoed 260kw@all 4's so i guess that translates to about 340hp@wheels and that is at 1.2bar or 17psi. I have almost travelled 5k since the rebuild and i will be adjusting the timing and winding the boost up to 1.35/1.4bar depending on the exhaust temps? i will also be putting a larger exhaust on the car as it is only a 3 inch. When i have done this i am expecting around the 280+kw@aw

i have heard that they are practically the same as HKS 2530's as far as size, but the HKS units can handle slightly more boost and also run cooler when pushed.

If anyone has more info i would really like to know!

cheers,

Francisco

[dangerous_daveo]

Would these be the same turbos the old gibson GTRs used to run at Bathurst and the like???

[rev210]

I just picked up a pair of turbo's built to this spec. Melv's old ones. He made over 300kw at all 4, from memory he wasn't running aftermarket cams , full boost was around 4500rpm. These turbo's are a tad larger than 2530's.

[djr81]

I just picked up a pair of turbo's built to this spec. Melv's old ones. He made over 300kw at all 4, from memory he wasn't running aftermarket cams , full boost was around 4500rpm. These turbo's are a tad larger than 2530's.

Rev210,

With the group A turbos you need to be aware that the relatively low efficiency of the compressor will give you a higher inlet temperature to you intercooler - ie have a think about the cooler.

If you use 25lb/min airflow & a pressure ratio of 2 as an example the temperature at the intercooler inlet will be almost ten degrees higher when using the group A turbos than when using the N1 turbos.

Have a look at the attached graph. It is a log of temperatures from my mates RX-7 when he is giving the thing a bootfull.

Blue is at the air filter

Pink is after the turbo

yellow is after the intercooler

cyan (Aqua) is at the throttle body

Note that the cooler is a cheap chinese type, but nonetheless has an efficiency of 71%

Note also the effects of heat soak.

at the end of the run there is an idle period. Note way the air filter temps rise when the car is sitting still, eg at the start of a hillclimb. This is the downside of having pod filters with no external air feed.

[fsmout]

sorry to hijack BNR, i have a few more questions below??

- Do the compressor sizes differ much for group A's and are they all ball bearing?

- What sort of power are people making with their setups?

- What is the max PSI efficiency, 1.3bar?? I have a big FMIC, 120mm thick?

Cheers,

Francisco

[Sydneykid]

The Group A turbos I have seen have all been plain bearing with 360 degree thrusts. Although I can't think of any reason why you couldn't use the Group A compressor and turbine with a ball bearing core. The R34GTR N1 turbos are ball bearing as are 2530's.

[djr81]

- What is the max PSI efficiency, 1.3bar??  I have a big FMIC, 120mm thick?

Cheers,

Francisco

Francisco,

There is a difference between the pressure ratio at the turbo compressor & the Manifold pressure (ie MAP) as seen by your ECU.

The pressure ratio equals (atmospheric pressure + boost) divided by the pressure at the turbo inlet.

Obviously there will be a pressure drop through the induction box (say 1 or 2 pounds) & a pumping loss across the intercooler (maybe the same again). Hence a PR of 2.5 at the turbo may be as low as 1 bar at the gauge. Hope that makes sense.

For hp, approx 10lbs/min of airflow will give you 100hp. (At the flywheel & a bit approximate). With two turbos, 30lb/s of airflow each will give 600hp. To achieve these flow rates you may then pressure ratios higher than the 2.6 which is the upper limit for the 66% efficiency island. The end result is that the inlet temp to the cooler on a warm day will be well above 100 degrees!

If, for the sake of the argument we use the following:

PR from turbo is 2.5.

Compressor Efficiency is 66%

Ambient air temp is 27 degrees.

This gives a turbo outlet temp of 133 degrees.

If we assume a 75% intercooler efficiency when then get a temperature at the throttle body of 53 degrees. However, with the addition of some heat soak into the system it is quite possible to see an air temperature into the motor of some 60 degrees. Fairly warm & it only gets worse on a hot day...

[fsmout]

ohhh, i understand.....thats bad. I have noticed it suffers from minor heat soak now at 1.2 bar, losing 1-2kw over various dyno runs!!

i currently have 260awkw so i guess they have quite a bit left? I will have to monitor the exhaust temp and inlet temp if i put some more boost through? I was hoping to run them on 20psi.....but i might have to check.

Do plain bearing turbo's continue to audibly spin after the engine is turned off for 15-20seconds?? I have been told that, the spinning sound is because they are ball bearing?

here are some pics of the turbo's when my engine was out

[djr81]

ohhh, i understand.....thats bad.  I have noticed it suffers from minor heat soak now at 1.2 bar, losing 1-2kw over various dyno runs!!

i currently have 260awkw so i guess they have quite a bit left?  I will have to monitor the exhaust temp and inlet temp if i put some more boost through?  I was hoping to run them on 20psi.....but i might have to check.

Do plain bearing turbo's continue to audibly spin after the engine is turned off for 15-20seconds??  I have been told that, the spinning sound is because they are ball bearing?

here are some pics of the turbo's when my engine was out

Something to be mindful of, rather than afraid of.

Depending on the dyno, 260awkW is about 360rwhp which is conservative for A turbos.

The Group A turbos are designed for relatively high pressure ratios - just that they are not the most efficient things going around.

[Boosting]

so are 32 n1 turbos a/r of 42 or something because i bought some seocnd hand turboss ages ago and they were a/r of 60 are mine n1's or group a

[djr81]

so are 32 n1 turbos a/r of 42 or something because i bought some seocnd hand turboss ages ago and they were a/r of 60 are mine n1's or group a

You will have to find the part number & then do a search on the net to match it up. It will be on the bearing housing.

[fsmout]

ok, thanks for that, where can i find the size of the compressor/exhaust wheels & specifications?

thanks again for the info!!