Lifted heads on 5.3!! Back pressure??
08-15-2013, 10:33 AM
#21
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talking to couple ppl they said adding another t76 would be abit more laggy to where even if my stall hits at 4700rpm it will still have a delay. but wouldnt a s480 do the same?
@OP......amazing build and sorry to hear about the issues.
Very glad I stumbled onto this thread because I am buildings something similar (240sx with a turbo 5.3) and was wondering what turbo would be adequate for this type of build. I am def sub'ed for more information. The BW turbos are awesome, great for the price, sound awesome (not important but a cool little perk to me), but they have a larger footprint then most turbos especially with their racecovers.
OP since you have your turbo setup pretty much where I am installing mine you may run into fitment issues with a S475. You may need to modify your plumbing to move the turbo location further towards the passenger headlight to accommodate the size. If you google 93 Nissan 240sx LS1/T56 Backhalf you will see where someone with an S13 had to mount their turbo to accommodate a large sized unit.
Very glad I stumbled onto this thread because I am buildings something similar (240sx with a turbo 5.3) and was wondering what turbo would be adequate for this type of build. I am def sub'ed for more information. The BW turbos are awesome, great for the price, sound awesome (not important but a cool little perk to me), but they have a larger footprint then most turbos especially with their racecovers.
OP since you have your turbo setup pretty much where I am installing mine you may run into fitment issues with a S475. You may need to modify your plumbing to move the turbo location further towards the passenger headlight to accommodate the size. If you google 93 Nissan 240sx LS1/T56 Backhalf you will see where someone with an S13 had to mount their turbo to accommodate a large sized unit.
Awesome, nice to meet you. Im always looking for other 5.3 turbo 240 owners to relate stuff with. Yes I already took measurements in fitting a s475 in that area, it should fit fine but my main hassle is gonna be DP, might just have to delete the exhaust.
See I already took time out couple months ago to make this a twin 76mm setup and have already figured out how to make it work, but im stuck in picking big single or twins.
08-15-2013, 10:55 AM
#23
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(hope this isn't hijacking the thread... thought it might be relavent to OP issues).
08-15-2013, 11:27 AM
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Would a bigger wastegate alleviate the problem of too much backpressure? Wondering if my 44mm wastegate is causing my setup to fall over at 5500 rpm. Would a 60mm wastegate fix the backpressure issue?
(hope this isn't hijacking the thread... thought it might be relavent to OP issues).
(hope this isn't hijacking the thread... thought it might be relavent to OP issues).
I am in the same boat with my GTO but I shift at 5800 to alleviate major back pressure issues causing damage.
OP the S475 with the 83mm wheel and 1.0 a/r should be pretty cheap, spool nicely and meet your power goals.
08-15-2013, 12:19 PM
#25
On The Tree
Changing a wastegate won't fix this issue. They are talking about pre-turbine back pressure for a given amount of boost. Going to a larger gate will only stop boost creep (which isn't the issue). Going with less boost pressure will drop backpressure, but who wants to do that? 
With that turbo on a 5.3 I bet you are more like 3:1 backpressure to boost pressure.
With that turbo on a 5.3 I bet you are more like 3:1 backpressure to boost pressure.
08-15-2013, 12:35 PM
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Would a bigger wastegate alleviate the problem of too much backpressure? Wondering if my 44mm wastegate is causing my setup to fall over at 5500 rpm. Would a 60mm wastegate fix the backpressure issue?
(hope this isn't hijacking the thread... thought it might be relavent to OP issues).
(hope this isn't hijacking the thread... thought it might be relavent to OP issues).
His issues are the small exhaust wheel on a v8 engine with a lot of boost. The 64-68mm turbine wheels will work below 10psi or so but above that they become a choke point as the compressor outflows the turbine.
I am in the same boat with my GTO but I shift at 5800 to alleviate major back pressure issues causing damage.
OP the S475 with the 83mm wheel and 1.0 a/r should be pretty cheap, spool nicely and meet your power goals.
I am in the same boat with my GTO but I shift at 5800 to alleviate major back pressure issues causing damage.
OP the S475 with the 83mm wheel and 1.0 a/r should be pretty cheap, spool nicely and meet your power goals.
Changing a wastegate won't fix this issue. They are talking about pre-turbine back pressure for a given amount of boost. Going to a larger gate will only stop boost creep (which isn't the issue). Going with less boost pressure will drop backpressure, but who wants to do that?
With that turbo on a 5.3 I bet you are more like 3:1 backpressure to boost pressure.
With that turbo on a 5.3 I bet you are more like 3:1 backpressure to boost pressure.
08-15-2013, 12:48 PM
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Talk Forced inductions on here. I bet you could get the S475 with 83mm turbine for 800 or less.
Edit.... They have it listed for $649 on their website.
Edit.... They have it listed for $649 on their website.
Last edited by big reg; 08-15-2013 at 01:05 PM.
08-15-2013, 01:49 PM
#29
Wrong turbo..... a turbine wheel smaller then a P-trim has no place on a V8. Also that compressor wheel is mismatched as a 76mm should not be driven with anything smaller then a Q-trim or F1-68.
08-16-2013, 06:10 AM
#31
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so if the compressor wheel is mismatched on the 76mm and I go ahead and add another 76mm then what would be the cause and effect of when both compressor wheels outflow the turbine? or will it even get to that point?
08-16-2013, 07:04 AM
#32
I'd go with something like this if you wanted a cheap turbo (600 shipped) that wasn't such a physically huge monster like the BW brand. I love my 75mm BW turbo, but it was a bastard to fit in my tiny engine bay!
Compressor Wheel (Major/Exducer) 80/108mm
Turbine Wheel (Major/Inducer) 77.4/88.9 mm
1.15AR
http://www.ebay.com/itm/CXRacing-GT45-GT45R-Ball-Bearing-Turbo-Charger-80mm-wheel-T4-1-15AR-Big-Power-/181106806132?pt=Motors_Car_Truck_Parts_Accessories&hash=item2a2ace8d74&vxp=mtr
Then I'd swap cams so something with less duration/overlap.
Compressor Wheel (Major/Exducer) 80/108mm
Turbine Wheel (Major/Inducer) 77.4/88.9 mm
1.15AR
http://www.ebay.com/itm/CXRacing-GT45-GT45R-Ball-Bearing-Turbo-Charger-80mm-wheel-T4-1-15AR-Big-Power-/181106806132?pt=Motors_Car_Truck_Parts_Accessories&hash=item2a2ace8d74&vxp=mtr
Then I'd swap cams so something with less duration/overlap.
08-16-2013, 07:42 AM
#33
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I'd go with something like this if you wanted a cheap turbo (600 shipped) that wasn't such a physically huge monster like the BW brand. I love my 75mm BW turbo, but it was a bastard to fit in my tiny engine bay!
Compressor Wheel (Major/Exducer) 80/108mm
Turbine Wheel (Major/Inducer) 77.4/88.9 mm
1.15AR
Cxracing GT45 GT45R Ball Bearing Turbo Charger 80mm Wheel T4 1 15AR Big Power | eBay
Then I'd swap cams so something with less duration/overlap.
Compressor Wheel (Major/Exducer) 80/108mm
Turbine Wheel (Major/Inducer) 77.4/88.9 mm
1.15AR
Cxracing GT45 GT45R Ball Bearing Turbo Charger 80mm Wheel T4 1 15AR Big Power | eBay
Then I'd swap cams so something with less duration/overlap.
IVE been eyeing the heck out of that thing. lol
08-16-2013, 12:59 PM
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There is your answer right there. That is a steal. I was looking at their GT42 turbo too but no warranty is what scares me. At that price though I can buy 4 to my current GTK1000 or 3 to the Turbonetics 7675 I was looking at. If it goes, swap in another.
Last edited by big reg; 08-17-2013 at 06:06 AM.
08-16-2013, 01:05 PM
#35
The quality control on the BW stuff is leaps and bounds ahead of the china stuff. But FWIW I ran a cxracing 72mm for awhile on my buick motor. Worked great. (was a journal bearing though). VSracing also sells similar turbos for similar prices. Think they even have an 88 with the same exh wheel setup.
08-16-2013, 05:53 PM
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https://ls1tech.com/forums/forced-in...sults-vid.html
Here is a link to my dyno graph with a 5.3 and on3 76mm with a .96 ar. As you can tell it made descent power, but noses off at about 5800. I've been thinking about going to a s475 myself.
Here is a link to my dyno graph with a 5.3 and on3 76mm with a .96 ar. As you can tell it made descent power, but noses off at about 5800. I've been thinking about going to a s475 myself.
08-17-2013, 08:48 AM
#39
Never used that exact turbo but I can't tell that using a journal bearing and a bb turbo....the bb turbo usually spools faster and also provides better transient power. Meaning the turbo does not "loose as much efficiency between shifts". Hope that makes sense....3 hrs of sleep and morning shots don't always produce the best writing lol.
08-17-2013, 11:12 AM
#40
What fuel are you running? I can't find it here.
FWIW, I love my Precision 7875 on my 370ci motor. Pulls hard to 6300. We also setup a 5.3 with the same turbo and it went 158mph in the 1/4, pulls hard well past 6k with a GT2-3 cam.
And if you don't like Precision, Turbonetics now makes a turbo that's very similar in specs to the 76/7875. And these turbos would be MUCH easier to fit than the large frame BWs. I have a BW S372 as well and it is GIGANTIC compared to these other turbos.
FWIW, I love my Precision 7875 on my 370ci motor. Pulls hard to 6300. We also setup a 5.3 with the same turbo and it went 158mph in the 1/4, pulls hard well past 6k with a GT2-3 cam.
And if you don't like Precision, Turbonetics now makes a turbo that's very similar in specs to the 76/7875. And these turbos would be MUCH easier to fit than the large frame BWs. I have a BW S372 as well and it is GIGANTIC compared to these other turbos.