6870 vs 6875

[Old man 32 GTR]

I’ve done a search but haven’t been able to find anything. Is there anyone on here who understands turbos who would be able to explain the difference in how these turbos would behave / respond compared to one another. 
obviously housings can affect this so let’s compare 

1. 6870 gen 2, 1.0ar T4 divided rear 

2. 6875 gen 2, .96ar T4 rear 

now I know the 6875 is rated a little higher, will it actually make more power and how much will you sacrifice in lag? 

[burn4005]

Just compare the compressor and turbine maps...

Oh wait. They're precision turbos... you'll just have to go of what a mates dogs uncles bus drivers parrot reckons.

[r32-25t]

Wouldn’t the compressor maps be the same for the fact they’re the same compressor wheel and housing 

[Old man 32 GTR]

1 hour ago, r32-25t said:

Wouldn’t the compressor maps be the same for the fact they’re the same compressor wheel and housing 

Not sure, on their website says the 68/75 is a more modern design turbine

 

[SiR_RB]

68mm comp wheel will max out well before the 75 rear 

 

[Old man 32 GTR]

53 minutes ago, SiR_RB said:

68mm comp wheel will max out well before the 75 rear 

 

So there would be no reason to go 6875 over 6870? 
this is what I’m trying to find out, I’d like to actually talk to someone who is really switched on with turbos and not tied to any one brand. When I sell my motor I’ll probably let it go with the entire hot side. As my new motor is a 2.7, I’d like a turbo that is responsive, but can still make decent power and give a decent push when turned up. 

[BK]

Why not the 6466 then ? I tossed up going the 6870, then I thought why ? People are making 500 - 600rwkw with them and it will always be more responsive than the 6870, so I went the 1.00a/r 6466.

[SiR_RB]

As Bk said, seriously consider the 6466

 

if you have a full house head and a decent rear (1.00+ in size) I have seen the 6466 push 580ish kw and would be an absolute rocket on the street with amazing response with the 2.7

[Old man 32 GTR]

4 hours ago, BK said:

Why not the 6466 then ? I tossed up going the 6870, then I thought why ? People are making 500 - 600rwkw with them and it will always be more responsive than the 6870, so I went the 1.00a/r 6466.

This is what I’m thinking, but I’m also not a Precesion fan boy, so I’d like to know all my options, I’ve heard good things about the Garrett 3584rs, mixed reviews on the new G series, good things about Borg Warner, I’ve also looked at Xona rotor? 

[hattori hanzo]

4 hours ago, SiR_RB said:

As Bk said, seriously consider the 6466

 

if you have a full house head and a decent rear (1.00+ in size) I have seen the 6466 push 580ish kw and would be an absolute rocket on the street with amazing response with the 2.7

Did 146mph on the 580kw blue line dyno graph

 

have not been back since the tweaking of exhaust setup, also going a CNC Shimless head at the moment and redoing the pipework etc.

 

Keen too see how far we can push the 6466

 

 

 

[r32-25t]

26 minutes ago, hattori hanzo said:

Did 146mph on the 580kw blue line dyno graph

 

have not been back since the tweaking of exhaust setup, also going a CNC Shimless head at the moment and redoing the pipework etc.

 

Keen too see how far we can push the 6466

 

 

 

What size engine is that on?

[r32-25t]

5 hours ago, Old man 32 GTR said:

This is what I’m thinking, but I’m also not a Precesion fan boy, so I’d like to know all my options, I’ve heard good things about the Garrett 3584rs, mixed reviews on the new G series, good things about Borg Warner, I’ve also looked at Xona rotor? 

My problem with the new Garrett turbos is there’s currently no twin scroll option

[hattori hanzo]

3 hours ago, r32-25t said:

What size engine is that on?

2.8

 

 

[SiR_RB]

3 hours ago, hattori hanzo said:

2.8

 

 

What rear is on the 64 mate 

[hattori hanzo]

15 hours ago, SiR_RB said:

What rear is on the 64 mate 

it was .84 with the 146mph

Have since gone 1.15 but did not get any massive changes, have since gone to 4" dump and CNC head to assist unlocking a few more ponies.

goal is 150mph on a 6466

 

[Piggaz]

6 hours ago, hattori hanzo said:

it was .84 with the 146mph

Have since gone 1.15 but did not get any massive changes, have since gone to 4" dump and CNC head to assist unlocking a few more ponies.

goal is 150mph on a 6466

 

What gearbox?

[hattori hanzo]

52 minutes ago, Piggaz said:

What gearbox?

Holinger Sequential

[jaychen]

9 hours ago, hattori hanzo said:

it was .84 with the 146mph

Have since gone 1.15 but did not get any massive changes, have since gone to 4" dump and CNC head to assist unlocking a few more ponies.

goal is 150mph on a 6466

 

What boost was that at mate?

[hattori hanzo]

30psi on the nose 

it was not taking any more and making any more power, hoping the head unlocks a bit more and its capacity to take 35psi or so

[Old man 32 GTR]

Had a chat with the guy from Garrett turbos yesterday about turbo options, he recommended the G30 900hp or G35 900, said they would offer good response and solid top end, another option is the G35 1050hp, this turbo is to supersede the 3584rs and will be released in a T4 divided rear housing option in the 1st quarter of 2021.