Precision 4854b mfs need info - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

yomny · 04-07-2015, 10:21 PM

Alright I've searched earth and sky and can't find a single thing on the max psi this turbo could see before exceeding peak efficiency. I've contacted precision with no luck. I've seaeched around Google and on other forums but no luck. Precision doesn't return my emails and I think I read somewhere they don't do compressor maps. A little help from someone with some reliable info and some knowledge on boost maps? I read the turbo is good for about 360, not sure if that's crank estimate. Thanks.

mrk1 · 04-07-2015, 11:49 PM

I'm not sure how you would determine this with out a compressor map. I cant say I've ever seen a map from Precision, I know the equipment to create the maps is very expensive. 360 would be a very general crank hp number.

If you can locate a compressor map, plotting points isn't terribly hard. There are online calculators for it.

King Tut · 04-08-2015, 11:48 AM

LOL Precision.

yomny · 04-08-2015, 12:59 PM

lol yeah I know.. its what I've read that they don't want to spend the money on creating maps for blah blah reasons. I figured the only true way to do so is with a compressor map. I've been looking around at other 48mm wheels but I know that's not accurate. I guess if they rate the turbo at 360(not sure if wheel or crank lol) we could calculate the amount of lbs of air(please don't quote me on any of this I as I don't know the terminology correctly) it would move at max efficiency but this still doesn't give the psi. I read that its like 10hp per lbs of air or something of that aspect so 360 would mean 36lb of air @ ??

Quote:

Originally Posted by mrk1

I'm not sure how you would determine this with out a compressor map. I cant say I've ever seen a map from Precision, I know the equipment to create the maps is very expensive. 360 would be a very general crank hp number.

If you can locate a compressor map, plotting points isn't terribly hard. There are online calculators for it.

I'll see if they reply to my emails.. its not the end of the world if I can't figure it out. I just thought it'll be good to know the max to push with my current setup to choose fueling supply adequately.

MAPerformance · 04-08-2015, 01:16 PM

Precision rates their turbos at WHP. Which seems to be fairly accurate. I am making 322whp on pump with my 4854, I would imagine 360whp should be doable on E85 (or more boost). While tuning my car, I accidentally hooked up the boost controller the wrong way, and it hit 20psi during a pull, and honestly, it wasn't making that much more power than our original 12psi run. It was picking up more torque, but maybe 5-10whp gain from 12-20psi. Again, there could be a lot of variables going on at the time as well. I would imagine somewhere around 25-28psi would be pushing out of it's efficiency range. (this is a non scientific guess

)

Quote:

Originally Posted by yomny

lol yeah I know.. its what I've read that they don't want to spend the money on creating maps for blah blah reasons. I figured the only true way to do so is with a compressor map. I've been looking around at other 48mm wheels but I know that's not accurate. I guess if they rate the turbo at 360(not sure if wheel or crank lol) we could calculate the amount of lbs of air(please don't quote me on any of this I as I don't know the terminology correctly) it would move at max efficiency but this still doesn't give the psi. I read that its like 10hp per lbs of air or something of that aspect so 360 would mean 36lb of air @ ??

I'll see if they reply to my emails.. its not the end of the world if I can't figure it out. I just thought it'll be good to know the max to push with my current setup to choose fueling supply adequately.

yomny · 04-08-2015, 01:33 PM

20-28

I don't know why I had in mind that 15psi or so would be near its efficiency limit. Good to know though and thanks for the reply.

MAPerformance · 04-08-2015, 01:53 PM

Well, you still might be right. But I think if I tuned my car on E85, we could have made more power past 15psi. However, I never tested it, so I could be completely wrong lol. I mean, stock Evo turbos can run 27-28psi before they run out of steam, same with the stock STI turbo's. I would say the 4854 is in the same ballpark of those...

Quote:

Originally Posted by yomny

20-28

I don't know why I had in mind that 15psi or so would be near its efficiency limit. Good to know though and thanks for the reply.

04-07-2015, 10:21 PM	#1
yomny Senior Member Join Date: Jul 2012 Drives: 2013 FRS Whiteout Location: MIA Posts: 1,545 Thanks: 557 Thanked 469 Times in 340 Posts Mentioned: 33 Post(s) Tagged: 5 Thread(s)	Precision 4854b mfs need info Alright I've searched earth and sky and can't find a single thing on the max psi this turbo could see before exceeding peak efficiency. I've contacted precision with no luck. I've seaeched around Google and on other forums but no luck. Precision doesn't return my emails and I think I read somewhere they don't do compressor maps. A little help from someone with some reliable info and some knowledge on boost maps? I read the turbo is good for about 360, not sure if that's crank estimate. Thanks. __________________ GTX2867R, moto-tuned , tomei op , motiv fp , Invidia Q300 ti , Rota titan 17x9 +42 , nt555 255/40 , ST coilovers w/cascam , Hotchkis sways

04-07-2015, 11:49 PM	#2
mrk1 Senior Member Join Date: Mar 2013 Drives: Sterling BRZ Ltd Location: New England Posts: 1,702 Thanks: 403 Thanked 1,389 Times in 671 Posts Mentioned: 21 Post(s) Tagged: 2 Thread(s)	I'm not sure how you would determine this with out a compressor map. I cant say I've ever seen a map from Precision, I know the equipment to create the maps is very expensive. 360 would be a very general crank hp number. If you can locate a compressor map, plotting points isn't terribly hard. There are online calculators for it. __________________ The Build Thread GT28RS - eBoost2 - 3.91 Final Drive - Supra LSD

04-08-2015, 11:48 AM	#3
King Tut NASA SpecE30 Racer Join Date: May 2012 Drives: 2006 Honda S2000 Location: Gulf Breeze, FL Posts: 7,279 Thanks: 607 Thanked 5,759 Times in 3,055 Posts Mentioned: 274 Post(s) Tagged: 10 Thread(s)	LOL Precision. __________________ - King Tut Street/Track Car: 2006 Honda S2000 TT3 \|\| Race Car: 1987 BMW 325is SpecE30 \|\| Tow Vehicle: 2014 RAM 1500 EcoDiesel Sold Cars: 2012 BMW M3 \|\| 2013 Subaru BRZ \|\| 2012 Porsche Cayman R \|\| 2009 Chevrolet Z06 \|\| 2009 BMW M3 \|\| 2004 BMW M3 \|\| 2004 Nissan 350Z

04-08-2015, 01:33 PM	#6
yomny Senior Member Join Date: Jul 2012 Drives: 2013 FRS Whiteout Location: MIA Posts: 1,545 Thanks: 557 Thanked 469 Times in 340 Posts Mentioned: 33 Post(s) Tagged: 5 Thread(s)	20-28 I don't know why I had in mind that 15psi or so would be near its efficiency limit. Good to know though and thanks for the reply. __________________ GTX2867R, moto-tuned , tomei op , motiv fp , Invidia Q300 ti , Rota titan 17x9 +42 , nt555 255/40 , ST coilovers w/cascam , Hotchkis sways

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