T04b S-trim vs Stock S5 Ht-18 Turbo?
I have all the parts, I'm just trying to decide what to use on a stock ported s4 TII engine: Hybrid T04B S-trim vs S5 stock.
1. Would a T04b S-trim hybrid turbo hold boost at high rpm better than the S5 stock ht-18 turbo? 2. Does the v-trim wheel actually improve response over the s-trim or stock turbo? Based on the compressor maps, the v-trim seems ideal for a stock port motor, but I'm not sure how exactly that translates to the real world. Some background: So I finally decided to open up the blown T04b hybrid I've had on the shelf and was disappointed to find an S-trim wheel inside. From what I've gathered, the T04b s-trim and stock compressor have similar outputs with a slight nod going to the s-trim. I'd be thrilled with 300hp @ the flywheel, but that seems like a pretty lofty goal for this turbo. That's also the ceiling for the rest of my fuel system and longevity of the car. The compressor inlet has also been modified to accept the 2.5" stock turbo inlet duct, so it is no longer a great candidate for a big power build. It is, however, great for an upgraded stock look I'm going for. I have driven with the s-trim turbo, but its 25 year old bearings failed in under 10k miles. So I don't know if there is a difference between new and whatever condition I got it in. Anyways, I'm seeing if I can get a modest power bump, increase the power band into the upper rev's and lower IAT's without losing the responsiveness of the turbo. Thanks. |
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here is the stock compressor map, so you can compare. no idea what unit Gc is.
the S wheel seems like it does 300flywheel@10psi... |
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IF Gc = 10lb/min, 200hp is about where the stock turbo maxes out at 1.6 bar (~9 psi)...makes sense to me.
Seeing how hard people have pushed the stock turbo, I wouldn't be surprised if the S-trim can put out 300 up at about 20 psi or so. It just makes me nervous to run that high with the stock pressure sensor and Rtek timing maps. It does seem to be a nice happy turbo for 250hp @ 10psi though. I am concerned about running the turbo hard outside its efficiency ranges since I'll be using the TMIC. Unless there's some glaring problem I'm overlooking, looks like I'm going to go with the hybrid s-trim. |
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An S-trim has both a larger inducer and exducer than stock, and since a stock turbo is capable of around 300 BHP (~250 WHP w/ 17% drivetrain loss), it should be plenty capable of that goal.
Since that stock turbo map has unknown units, we can also estimate from a similarly-sized wheel. A T3 50 trim is just slightly smaller on both the inducer and exducer. Stock compressor: 63 x 43.68 mm, 48 trim Garrett T3 50 trim: 60.12 x 42.52mm 8 Blade T04B Garrett PN, exducer x inducer, trim, flow 409179-0021, 70 x 48.36 mm, 48 trim, S trim (37 lbs/min) 409179-0025, 70 x 55.37 mm, 63 trim, V trim (48 lbs/min) http://www.squirrelpf.com/turbocalc/map.php https://www.rx7club.com/showthread.p...ht=stock+turbo Garrett T3 50 trim http://turbocharged.com/catalog/comp...mages/Fig3.gif S-trim map https://www.rx7club.com/attachment.p...1&d=1337636582 V-trim map https://www.rx7club.com/attachment.p...1&d=1337636587 If you plot a point at 1.7 pressure ratio (10 psi) and 30 lbs. per min. airflow, the T3 is somewhere around the 50% efficiency island, the S-trim is in the 60% region and the V-trim is at 70%. I can tell you that my V-trim feels no less responsive than stock, but it builds much more torque and pulls much harder to redline. Datalogs show at least 25% more peak airflow according to the AFM, and that's at only 10-11 psi by redline. It's more efficient than my stock compressor was, but at the same time I'm cramming more air through the TMIC. IATs are similar to stock during short pulls, but it heatsoaks more easily. Water injection will be my cure. |
^Awesome info yet again. Thanks.
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284 RWHP ( DD dyno ) at around 1 bar ( leaky gauge ) is the best i have seen from a s4 , s trim highflow with modified internal gate and modified backing plate
( one of my motor and turbo builds ) faster spool than V trim but still not as good as stock |
Im curious to know if anyone experiences surge with with the V trim. The reason why I ask is because Im using the stock compressor map vs the V trim.
Looking at the stock compressor map it shows 1500 rpms is a little less than .5 on the X axis. It then lines up around 1.2 on the Y axis. On the stock compressor map, it starts to reach the 75% efficiency range when the X axis meets the number 1 and the Y axis around the 1.4. When you compare the numbers to the V trim wheel you are in the surge area at those two points (X axis = 1 and Y axis = 1.4) Who knows what RPM youre in at this point but it is not the most amount of air your engine produces (redline) and its definitely in the surge area.
Originally Posted by RotaryRocket88
(Post 11098208)
If you plot a point at 1.7 pressure ratio (10 psi) and 30 lbs. per min. airflow, the T3 is somewhere around the 50% efficiency island, the S-trim is in the 60% region and the V-trim is at 70%.
Lets not forget to about atmospheric air pressure. Pressure Ratio is defined as absolute outlet air pressure divided by absolute inlet air pressure. In my case here in Florida the atmospheric pressure = 14.7. So If I where to boost 10 psi on the v trim and I want to find out what pressure ratio is going to land me in, I would use this equation. absolute outlet pressure + boost pressure divided by absolute air inlet So 14.7 + 10 psi divided by 14.7 = 1.68 (round to the nearest tenth) = 1.7. But if you are at a higher altitude let say 5000ft above sea level then your ambient air pressure would be 12.4. In that case then you would use this equation. 12.4 + 10 psi divided by 12.4 = 1.8 This points out that you would need MORE air for a given PSI than at sea level, so they are working harder for a same pressure level than a turbo would be at sea level. |
Originally Posted by 2-N-D-pink
(Post 11104537)
Im curious to know if anyone experiences surge with with the V trim. The reason why I ask is because Im using the stock compressor map vs the V trim.
Looking at the stock compressor map it shows 1500 rpms is a little less than .5 on the X axis. It then lines up around 1.2 on the Y axis. On the stock compressor map, it starts to reach the 75% efficiency range when the X axis meets the number 1 and the Y axis around the 1.4. When you compare the numbers to the V trim wheel you are in the surge area at those two points (X axis = 1 and Y axis = 1.4) Who knows what RPM youre in at this point but it is not the most amount of air your engine produces (redline) and its definitely in the surge area.
Originally Posted by 2-N-D-pink
(Post 11104537)
Lets not forget to about atmospheric air pressure...
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Good info. have a s5 t-ll with street port and haltech going together. also have an s trim compressor and housing. altitude is mostly from 3k to 9k. Am i going to get into trouble with the s trim using the stock top mount ic? Car weighs 1400#
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Originally Posted by reo
(Post 11105094)
Good info. have a s5 t-ll with street port and haltech going together. also have an s trim compressor and housing. altitude is mostly from 3k to 9k. Am i going to get into trouble with the s trim using the stock top mount ic? Car weighs 1400#
actually if you were to give the stock IC more/better airflow it'll help |
Originally Posted by j9fd3s
(Post 11105154)
well yes, you will get into trouble, 300hp in a 1400lbs car!
actually if you were to give the stock IC more/better airflow it'll help |
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