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Old 02-20-2019, 12:42 PM   #51
Stiggy Pop
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the maps make the S257 look the best. This is where I wonder where the maps aren't telling the whole story.

maybe I'll just rebuild the damn holset after all
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Old 02-20-2019, 03:48 PM   #52
Duder
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I really doubt you'll be flowing over 60 lb/min... was that operating point specific to your setup or taken from some other comparison?
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Old 02-20-2019, 04:52 PM   #53
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I really doubt you'll be flowing over 60 lb/min... was that operating point specific to your setup or taken from some other comparison?
I'd tend to agree. It's ostensibly based on my setup, here's what I gave him:

Car is a Volvo 242 with a Volvo b230ft engine
2.3l 8 valve, 96.5mm bore, 80mm stroke
8.5:1 SCR, built bottom end and a high flowing head, 7000rpm rev limit
twin scroll tube header flanged for t3
I have been running a 12cm HX35 for a few years
goal of ~450bhp on 93pump

It's a street driven car with an occasional track day. Looking to improve overall power output and transient response over the HX35. A slight improvement in spool would be nice but not necessarily the primary objective, currently seeing 23psi around 3900rpm. I am mostly looking for better on-off throttle response without sacrificing top end.

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Old 02-20-2019, 07:17 PM   #54
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So what's this guy's deal then? Can he show you how he arrived at 60 - 65 lb/min? Like with math?
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Old 02-20-2019, 07:22 PM   #55
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Am I the guy being referenced? I meant I didn't/don't think you'd be happy with a turbo with max flow below ~65 lb/min. Just doesn't seem worth it to me because I bet you'll want more power in the future. I don't think you'll be flowing the 65 lb/min, but I think you'll want the headroom. I just know at my altitude, my 7064 was out of steam and not doing what I wanted, so I got the 7670 for the extra 10 lb/min flow.
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Old 02-20-2019, 07:54 PM   #56
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Am I the guy being referenced? I meant I didn't/don't think you'd be happy with a turbo with max flow below ~65 lb/min. Just doesn't seem worth it to me because I bet you'll want more power in the future. I don't think you'll be flowing the 65 lb/min, but I think you'll want the headroom. I just know at my altitude, my 7064 was out of steam and not doing what I wanted, so I got the 7670 for the extra 10 lb/min flow.
Ah ok, sorry man. I thought maybe Mike got this from someone on vwvortex since the plots looked identical to that thread referenced earlier.

Certainly valid to build in some headroom for future improvements. But at around ~3.0 pressure ratio a 2.3L / 7000rpm redblock is maybe only ever going to reach 55 lb/min.
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Old 02-20-2019, 08:10 PM   #57
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Ah ok, sorry man. I thought maybe Mike got this from someone on vwvortex since the plots looked identical to that thread referenced earlier.

Certainly valid to build in some headroom for future improvements. But at around ~3.0 pressure ratio a 2.3L / 7000rpm redblock is maybe only ever going to reach 55 lb/min.
No worries at all. Maybe he did talk to someone else. I'm not sure if I'm the guy he's referencing. I didn't make any of the plots he's posted; we've just been talking about my turbo selection since our setups are very similar.

I agree with you. I'm just trying to say I'm much happier with my 7670 than my 7064 and can hit my boost target.

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Old 02-20-2019, 08:19 PM   #58
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Maybe he did. I'm not sure I'm the guy he's referencing. I didn't make any of the plots he's posted; we've just been talking about my turbo selection since our setups are very similar.

I agree with you. I'm just trying to say I'm much happier with my 7670 than my 7064 and can hit my boost target.
My fault - I should have never been born. If I'd never been born then none of this would have ever happened.

Looking at the compressor map for an EFR7064 I can see why you were running out of steam. I adjusted this match sheet I've been playing with for 4950 ft elevation (so 12.2 psi ambient pressure) - at about 2.5 pressure ratio, 46 lb/min, you were way over near the choke line and getting down towards 60% efficiency or lower. Certainly appropriate to jump up to a higher-flowing compressor at that point.
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Old 02-20-2019, 08:37 PM   #59
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Originally Posted by Duder View Post
My fault - I should have never been born. If I'd never been born then none of this would have ever happened.

Looking at the compressor map for an EFR7064 I can see why you were running out of steam. I adjusted this match sheet I've been playing with for 4950 ft elevation (so 12.2 psi ambient pressure) - at about 2.5 pressure ratio, 46 lb/min, you were way over near the choke line and getting down towards 60% efficiency or lower. Certainly appropriate to jump up to a higher-flowing compressor at that point.
Lol. I'm really not offended in the slightest. I defer to you (obviously, you're the expert) and was mostly basing my recommendations on my own circumstances, which don't really match up with his. When I drove my car with the 7064 at sea level the response was so good that I don't think the jump to a 7670 is unreasonable.

It's even worse than 4950 up here. The last time I was at the track, the DA was 7500 ft. I just needed to move my map to the right a bit to get to a more efficient point.

I have played with Borg Warner's match bot, but I'm sure it's overestimating my mass flow, although I am at around a pressure ratio of 3.6. I would really be interested in knowing the VE of a worked over redblock.
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Old 02-20-2019, 08:58 PM   #60
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Damn, 7500 ft. DA is pretty extreme. In that case yes, you will get near 60 lb/min at 3.6 PR. Not sure if Stiggy would ever need to operate there though.

76mm compressor does seem like a smart choice for his engine, even if it won't be using the whole available flow range.
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Old 02-20-2019, 10:49 PM   #61
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Haha sorry guys. This does tie back to that vwvortex link I posted. Thatís the guy who produced the overlaid compressor maps. I havenít gone back to him to ask for more detail yet - show your work for full credit right?

Iím in agreement on the 76mm compressor (although the efr 7163 looks awesome). Think I know what the two options are and just need to pick between EFR and GTX, so I canít lose! Well, except money. Iíll lose a bunch of money.
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