Twin 6466's to small for a 408
12-17-2015, 10:11 AM
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Twin 6466's to small for a 408 Here's the quick down and dirty. I have a 408 with 317's and forged everything. Currently running twin 70mm turbonetics with journal bearings and cast wheels. The car makes 800+ whp with pump and meth @16lbs, through a 9inch and 6 speed. Does anyone think 6466's would be too small for that motor. I rev to about 6200 and currently the car has to much lag for the street. I was told by a precision guy that those turbos should be fine to about 1200 whp and that for my power goals (around 900-1000 whp) i wouldnt gain anything going to the 6766. Any input is greatly appreciated guys.
Last edited by ranedoss27; 12-17-2015 at 10:11 AM. Reason: I cant spell
12-17-2015, 10:19 AM
#2
Here's the quick down and dirty. I have a 408 with 317's and forged everything. Currently running twin 70mm turbonetics with journal bearings and cast wheels. The car makes 800+ whp with pump and meth @16lbs, through a 9inch and 6 speed. Does anyone think 6466's would be too small for that motor. I rev to about 6200 and currently the car has to much lag for the street. I was told by a precision guy that those turbos should be fine to about 1200 whp and that for my power goals (around 900-1000 whp) i wouldnt gain anything going to the 6766. Any input is greatly appreciated guys.
What A/R EH are do you have on there. If .96AR or bigger you are good to go.
You could make 1000 on pump with these guys. They are incredible.
12-17-2015, 11:23 AM
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12-17-2015, 04:13 PM
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I've come to notice that on this site you get more Feed back from people by talking **** about a product then you do by just asking for input. So on that note, precision turbos are garbage and that company should be put out of business!!! Who's with me?!?!
12-17-2015, 04:40 PM
#7
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I've made 900whp on a 4 banger @ 50 psi with these.
******* LOVE big boost on a small motor, so I assume they will flow well you us int he low 20's. They will make more power everywhere, but cost 4x as much as your current turbos.
******* LOVE big boost on a small motor, so I assume they will flow well you us int he low 20's. They will make more power everywhere, but cost 4x as much as your current turbos.
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12-17-2015, 07:17 PM
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Does any one think 18-20 lbs would be to low, that's kind of my limit with the 317 heads, I know boost is a relative number just looking for some different perspectives
12-17-2015, 11:38 PM
#9
.96ar exhaust housings are the reason why you have too much lag. you need to step down to .68ar's. What size is your turbine wheel? I would go with either Turbonetics 6665BB or 6466BB with HPC billet compressor wheel. Precision turbo is just way overpriced IMHO, but if you have the means for their ball-bearing units with billet compressor wheel, then go with Precision if that's what you want. GL!
12-18-2015, 07:40 AM
#10
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Having tried 6266 and 6466 with 0.58, 0.68 and 0.81 housings on 4 cyl engiens, I can safely say there is negligible difference in spool between them, and a nice difference in power
As long as you arent looking to make 25-30psi boost with the 408 then I dont see you having any problems at all and you will have no problems making well over 1000hp
On a slightly better budget you could go for the BW S364FMW's like I have, almost same dimensions compressor albeit with BW's 68mm turbine wheel.
Perhaps a little loss in spool and transient response between the Precision and the BW, big difference in price and no worries at all about reliability.
You could even step down to a 6266 or the BW S362FMW's for a little better spool but on a 408 I really dont think you'd have a problem.
Under exactly what conditions are you suffering poor spool, and what sort of rpm etc are you making boost at, or making full boost at ?
Mine's only a 382 and I'm quite happy with mine under 98% of circumstances.
As long as you arent looking to make 25-30psi boost with the 408 then I dont see you having any problems at all and you will have no problems making well over 1000hp
On a slightly better budget you could go for the BW S364FMW's like I have, almost same dimensions compressor albeit with BW's 68mm turbine wheel.
Perhaps a little loss in spool and transient response between the Precision and the BW, big difference in price and no worries at all about reliability.
You could even step down to a 6266 or the BW S362FMW's for a little better spool but on a 408 I really dont think you'd have a problem.
Under exactly what conditions are you suffering poor spool, and what sort of rpm etc are you making boost at, or making full boost at ?
Mine's only a 382 and I'm quite happy with mine under 98% of circumstances.
12-18-2015, 08:07 AM
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Somethings wrong if a .68 doesnt outspool a .96 lol
6466 are fine. If your only looking for 18-20 psi 1000 hp or so, i would run .68-.81 a/r for faster spool on street. Should be nicer with the 6 spd
Your current turbonetics should be better off with a .68 to .81. I would do that first if you dont wanna spend money on new turbos
My 72 mm turbonetics with 68mm turbines spool faster on .81 ar than my 7065's that had a .96 ar
My old 6065's with .68 were instant boost. 7065 with .68 was only tad slower spool than the 60's. Ar has alot to do with spool
6466 are fine. If your only looking for 18-20 psi 1000 hp or so, i would run .68-.81 a/r for faster spool on street. Should be nicer with the 6 spd
Your current turbonetics should be better off with a .68 to .81. I would do that first if you dont wanna spend money on new turbos
My 72 mm turbonetics with 68mm turbines spool faster on .81 ar than my 7065's that had a .96 ar
My old 6065's with .68 were instant boost. 7065 with .68 was only tad slower spool than the 60's. Ar has alot to do with spool
Last edited by Orr89rocz; 12-18-2015 at 09:52 AM.
12-18-2015, 08:12 AM
#12
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Yes, off boost it is also completely choking the engine making it very lethargic. A/R IMO plays a much smaller role in spool than people think, perhaps even less so on larger motors although the ones I tried were all on a 2.35
The larger housings on the same engine were noticeably better everywhere, even during normal driving.
Smaller isnt always better in terms of spool, if there isnt enough energy to actually drive the compressor to make boost which presumably is what was happening at lower loads. I'd say with a much smaller compressor it would be a very different story though
The larger housings on the same engine were noticeably better everywhere, even during normal driving.
Smaller isnt always better in terms of spool, if there isnt enough energy to actually drive the compressor to make boost which presumably is what was happening at lower loads. I'd say with a much smaller compressor it would be a very different story though
12-18-2015, 09:58 AM
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Yes, off boost it is also completely choking the engine making it very lethargic. A/R IMO plays a much smaller role in spool than people think, perhaps even less so on larger motors although the ones I tried were all on a 2.35
The larger housings on the same engine were noticeably better everywhere, even during normal driving.
Smaller isnt always better in terms of spool, if there isnt enough energy to actually drive the compressor to make boost which presumably is what was happening at lower loads. I'd say with a much smaller compressor it would be a very different story though
The larger housings on the same engine were noticeably better everywhere, even during normal driving.
Smaller isnt always better in terms of spool, if there isnt enough energy to actually drive the compressor to make boost which presumably is what was happening at lower loads. I'd say with a much smaller compressor it would be a very different story though
12-18-2015, 11:02 AM
#16
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With right build/CR etc, I dont see why it wouldnt do 13-1400 on pump.
However, as much as it's a great unit on smaller engines and I've used it to near 40psi boost, I'd be concerned about pushing them very hard on the much larger motor simply because of Precisions reputation and the turbo is operating under very different conditions trying to feed the larger motor.
For the price of them and if spending that sort of money wanting BB units, I'd be inclined to go for a pair of EFR's
if not, just a pair of Airwerks or the SXE's at less than half the price.
12-18-2015, 12:11 PM
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I would like to see the backpressure readings on that. 66mm turbine might be getting alittle small at that amount of exhaust flow. It would be a pretty impressive comp wheel to pass that air flow.
12-18-2015, 01:01 PM
#18
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Even above either of those, it's only a little over 1:1 manifold pressure vs boost.
The Precision 66mm wheel is thinner and freer than the BW 68mm on mine so I'd have no concerns at all about backpressure even with the 408.
Some of the big singles would be running far far higher.
There's a guy over on YB who's made near 1800hp on a pair of 6266's, although he's on methanol.
12-18-2015, 09:39 PM
#19
u guys are saying these stupid *** numbers.... my dads 6266's ball bearing water/oil cooled make around 850 on 22psi and he's pump with meth.. also a 416 ls3... of course a smaller motor will result in more boost and more power because theyll flow more, but goddamn 1500 and 1800hp........ please show me where thats happened with that size turbo. all you guys are high as hell.. twin 76's? yeah i see 1500 onna 416 to 427 inch motor on like 30-35 psi.... thats what it takes for that much power... and yeah those 64's run 40psi.... but they will not push that mch on any decent size ls motor.. theres just not enough turbine..