7675 vs 6870 vs 7168

**Commanderwiggin** · 10-09-2017, 01:05 AM

Figured I've spent enough time trying to pull up this information in the past that I may as well share a bit more openly for those looking to splurge on a turbo upgrade.

7675 Gen2 Open 0.96ar
6870 Gen2 Open 0.81ar
7168 Gen1 Open 0.81ar
All ball bearing turbos
E85 Fuel
27-29PSI; 7168 didn't have the 4port boost control and some other tuning optimizations.
Same old low comp motor, stock head - no porting, stock valves, built bottom end with stock hg.

Turbo Comparison.jpg

If I was going to go back from my 7675 to pick between the 7168 or 6870 I'd likely pick the 7168 to be honest but realistically my curiousity would probably try to get Precision to build a hybrid 7170 or 7270.

Now for efficiency. The 7168 was happiest around 23psi...the 6870 around 20psi and the 7675 seems to be really efficient up to about 27psi so far.

Exhaust backpressure on the 7168 was never measured but I suspect it would be the highest. This turbo also made 1020whp on an 11.5:1 compression motor which didn't live long due to a supertech failure.
6870 would peg 2:1 EBP:MAP. These turbos are happy up to about 1.4:1 ratios.
7675 has considerably lower EBP than the 6870 to be expected.

I have a fully built S54 that's been ready for a year which has a cutring, porting, higher comp and ferrea valvetrain which will go in sometime this year depending how long old bessy lives.

**95RogueM3** · 10-09-2017, 05:33 AM

Thanks for posting. I rarely drive mine, so have put a turbo upgrade on the back burner.....but still debate replacing my 6766 with either a 6870 or 7675. From your graph, it looks very similar to others I have seen where its a clear decision to be made between wanting it to hit harder, but obviously provide less headroom (6870) or whether you are okay with a delayed power onset but want more peak power (7675). From your graph, I really don't see the reason for the 7168 -- it doesn't seem to provide any benefit to either response or power compared to the 6870?

**Commanderwiggin** · 10-09-2017, 08:57 AM

Originally Posted by 95RogueM3

Thanks for posting. I rarely drive mine, so have put a turbo upgrade on the back burner.....but still debate replacing my 6766 with either a 6870 or 7675. From your graph, it looks very similar to others I have seen where its a clear decision to be made between wanting it to hit harder, but obviously provide less headroom (6870) or whether you are okay with a delayed power onset but want more peak power (7675). From your graph, I really don't see the reason for the 7168 -- it doesn't seem to provide any benefit to either response or power compared to the 6870?

In all honesty keep your 6766 as it's so close to 6870. Some (very few) people have pushed that turbo so hard on some dynos to inflate numbers. I like to target something that's efficient for my power goals. The 7168 in my testing would've done better with my 4port boost control and tuning changes that have been polished over the years so it's not an apples to apples comparison but moreso an extended guide. I still think theres some room for improvement with my 7675 which I'll dial further on the new motor. In my opinion if you upgrade...go directly to the 7675 otherwise keep what you have.

**95RogueM3** · 10-09-2017, 10:11 AM

Originally Posted by Commanderwiggin

In all honesty keep your 6766 as it's so close to 6870. Some (very few) people have pushed that turbo so hard on some dynos to inflate numbers. I like to target something that's efficient for my power goals. The 7168 in my testing would've done better with my 4port boost control and tuning changes that have been polished over the years so it's not an apples to apples comparison but moreso an extended guide. I still think theres some room for improvement with my 7675 which I'll dial further on the new motor. In my opinion if you upgrade...go directly to the 7675 otherwise keep what you have.

Thanks for the insight. Agreed on the 6870 not being worth it for what might amount to ~80-100whp more with some sacrifice in top end (they seem to choke when pushed). I saw some love last week (from Alpha at Induction) for the no longer produced 7175 but have never been in a car with one...not sure its that much better than a 7675 given the advancements they've made with the 7675.

**E36 HateR** · 10-09-2017, 10:44 AM

Lots of good info here. 7675 was my next turbo before i decided on the sxe369.

6870 is a great turbo as far as response and powerband go but i dont think its wortth it to go from 6766 to 6870.

**Butters Stoch** · 10-09-2017, 10:44 AM

7675 on a steed twin scroll would be a nasty setup. That twin scroll a world of difference in my setup. I always complained about spool w/ 6466 now its almost too quick. I could give up 800rpm and be happy.

Sent from my E6782 using Tapatalk

**E36 HateR** · 10-09-2017, 11:09 AM

Originally Posted by Butters Stoch

7675 on a steed twin scroll would be a nasty setup. That twin scroll a world of difference in my setup. I always complained about spool w/ 6466 now its almost too quick. I could give up 800rpm and be happy.

Sent from my E6782 using Tapatalk

Open scroll holset to twin scroll borg warner netted me over 1000rpm in spool, twin is the truth.

**Butters Stoch** · 10-09-2017, 11:16 AM

Mine too. .81 t4 open to 1.0ar scored me around 1200-1300rpm. I wasn't hitting 20# till about 4300-4400 now, 3100-3200. Crazy stuffs

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**95RogueM3** · 10-09-2017, 11:41 AM

Twin scroll with a QSV is pretty exceptional.

**pbonsalb** · 10-09-2017, 11:43 AM

When you want 1000 rwhp, you are trading off bottom end power for top end power. With the S54, you have the dual vanos that helps a bit, and you have the 8000 rpm redline that lets you have a good powerband even with a big turbo that spools later. For the big power people, a twinscroll manifold might hinder the top end power they are after.

**PEI330Ci** · 10-10-2017, 01:51 AM

This is the highest HP comparison of turbos I have ever seen for a BMW 6 cylinder application. Considering how long Kenton has run at this power level.....I consider him an expert....and appreciate the fact that he shares his data so openly. Most don't at this level....

The interesting thing to me is how consistent the shape of the power band is across many turbo and manifold combinations. Most dynos I have seen have peak HP in the 7500 area or below. If you look at a stock S54 graph, this is the case as well. Ironically, BMW rates peak HP on the S54 at 7900 RPM? I find that strange, considering the real world results.

If you applied a scaling factor to a stock S54 dyno, it would be really close to the power band above. Other similar engines like the 2JZ require a power band shift to achieve similar numbers versus their stock engine.

Remarkable engine the S54 is......

...and no Kenton, I'm not converting from the M54....yet.

**Commanderwiggin** · 10-10-2017, 02:16 AM

Thanks for the props...I'm just a crazy guy feeding an addiction.

Originally Posted by PEI330Ci

...and no Kenton, I'm not converting from the M54....yet.

Oh really?
JNlvV.jpg

**being3** · 10-10-2017, 09:19 AM

Glad u shared ... some real good data here that’s helpful ... plus I love comparisons ...

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**Mod Addict** · 10-11-2017, 11:12 AM

Originally Posted by Butters Stoch

7675 on a steed twin scroll would be a nasty setup. That twin scroll a world of difference in my setup. I always complained about spool w/ 6466 now its almost too quick. I could give up 800rpm and be happy.

Sent from my E6782 using Tapatalk

Bingo, I’ve been wanting this turbo for years. ;-)

**Butters Stoch** · 10-11-2017, 02:51 PM

Originally Posted by Mod Addict

Bingo, I’ve been wanting this turbo for years. ;-)

Well, with a twin scroll that turbo would be insane. OP's testing doesn't even take into consideration the apples to oranges back housing. For a .96AR that 7675 is cruising. I'm blown away honestly.

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**Commanderwiggin** · 10-11-2017, 09:05 PM

Originally Posted by Butters Stoch

Well, with a twin scroll that turbo would be insane. OP's testing doesn't even take into consideration the apples to oranges back housing. For a .96AR that 7675 is cruising. I'm blown away honestly.

Sent from my E6782 using Tapatalk

I think with the 0.81A/R on the 7675 it would become a bit aggressive for spool...when this 7675 spools up you're going for a ride

It's given me that fresh adrenaline rush that no other turbo has given me...slingshot engaged :P

**e30polak** · 10-17-2017, 04:49 PM

Your car always impressed me at the Shift S3ctor events Kenton! For me the 6870 graph is so perfect! I would love that graph in a big 850i, with a 3.73 rear end and at least some 315s!

**Quicker10u** · 10-19-2017, 02:49 PM

Those are pretty impressive graphs and great info...I might switch to a smaller turbo at some point due to the laggy-ness of my 3586. I don't think the billet wheel is helping the situation any. It's hits hard, but the drivability is a bit of an on/off switch for me. It's romantic in a way. Like an old 911 Turbo...It's like "you're ok. You're safe with me. Starting to squeeze. FULL AXE MURDERER!" It's really spooling by 3700-3900 with the Schricks. Not sure if the Steed-Speed is helping as I am still new to the car and have no SPA experience to compare it to... How would a 6466 Compare with the 3586? Is there a practical solution to help with spool without sacrificing on the top end?