compound sizing for 4b

S

stothew

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ive done some messing around with different combos. currently have a garrett 51 comp. 57 turbine as my secondary and its very laggy. so ive decided to go with an hx30 i ran as a single and it is very quick. the primary i have been running is an hx52. the 52 spools fairly good considering i have 2/3 the cylinders. with some rough numbers i think i only need close to 50lb min for my hp goals of around 350. think an hx40 with 60/16 would be a better fit? the math involved is way over my head, so any help id appreciate. thank you

scott
 
So you're planning on running an hX30/HX52 setup?? I don't see an issue with that.
 
well i wasnt sure if the 52 would be too big. since i have to make a new hot pipe i wanted to make sure i did it with either a t3 or the odd 52 flange. wanted to know if something smaller than the 52 would be a better combo for quick flat torque curve.
 
What about a S366?
Of course if you already have the 52 I would run it for now.
 
im really wondering though if the 52 or 366 is too big for my power goals. since i only need 50lbs min. for around 350hp. would it be better to have something a little smaller to keep me always in the sweet spot of power and torque.
 
I'm interested in similiar power goals for a 3.9.

As a single the HX30 feels small to me. Maybe as a secondary it's just right for the 300-350 HP range?
 
yea as a single it lights super quick, but chokes off easily thats why im hoping to size a primary accordingly. the he341 i have is too slow to spool even with a lot of fuel. it is p pumped and have 7x.010 injectors.
 
I would do the 52, and use an external gate before the hx30 into the hotpipe. Should be the better of both worlds. Quick to light, good cooling and power on top.
 
341 should light pretty quick as a single on a 4B, on a mild 200HP VE 4BT. I haven't had the opportunity to push a P7100 4BT very far, but the VE ones get a lot of play around here. I haven't had much lag spooling any turbo that came on a 5.9 on a VE 4BT.
 
when you say much lag...what rpm would you say your 341 lights? i dont feel it lighting till about 2000 rpm. too laggy for my taste, it builds some boost before that but not really lit.
 
depending on which hy35 its either the same as the he341 or just different enough that you're splitting hairs. either way it spools a little too slow on a 4b. doesnt light till about 2000. at least not with my trans, 47rh. maybe quicker with something with a lower first gear or manual.
 
stothew said:
depending on which hy35 its either the same as the he341 or just different enough that you're splitting hairs. either way it spools a little too slow on a 4b. doesnt light till about 2000. at least not with my trans, 47rh. maybe quicker with something with a lower first gear or manual.
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I've put hy35 (very similar to HE341) turbos on a few 4B engines...of coarse we always tuned the engine around the turbo. One vehicle was a GMC Denali with a 4L80E...I was able to tune the transmission shift points around the power band of the engine and I also installed a 4k gsk (adjusted to max out at 3500 rpm under load) to extend the power into the turbos map range...the engine is making approx 250rwhp and gets 23 mpg average...between highway and city driving.
The trans has been out twice for upgrades since I tuned the engine and the last time they put a triple disc converter in it so I think it will hold now. LOL
 
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:lolly: i get a kick out of that. I work at a GMC dealer so i see denalis daily. Dont know what i would do if one came in with a 4b in it :bow:
 
Most people are completely oblivious a 4B conversion is something unique.

I can't say I have tuned with a tach on a 4B. Like Lee, I run them to 3500 under load and can't say I feel a "lack of spool" right off idle with the fueling set appropriately. I suspect I'm seeing 12-15 PSI by 1500?, but may be off some there as I don't have a tach, just my ears. A smooth smokeless takeoff with normal driving is the goal, but to tear it up from a stop it does take some fuel to get it going right now.

The 4B twins I'm leaning towards are a 341 hybrid top with a 52mm compressor wheel/sleeved compressor housing over an HX40, maybe larger primary, but I'm going to try the HX40 first.
 
I have done a bunch of thinking about 4bt Compound Turbo setups. Far as I've seen, no one has done it yet. They way I see it, the 4bt is 2/3rds the size of the 6bt. Basically you downsize the 6bt setup by a 3rd, ie; 60mm on a 6bt is equivalent to a 40mm on a 4bt. It should be equivalent in spool up time and longevity etc. Also, ball-bearing turbos have less friction compared to conventional turbos, so spool-up(full boost) is quicker. I have not had the chance to test various trim turbos, so this is all theory. If a well working 6bt compound setup is using a 60mm/90mm; then a 4bt should easily use a 40mm/60mm turbo setup, which is 2/3rds the size of the 6bt, because the 4bt has 2 less cylinders.

Please correct me(with proof) if I'm wrong guys. Thanks, Bradley
 
thirdstreettito said:
I have done a bunch of thinking about 4bt Compound Turbo setups. Far as I've seen, no one has done it yet. They way I see it, the 4bt is 2/3rds the size of the 6bt. Basically you downsize the 6bt setup by a 3rd, ie; 60mm on a 6bt is equivalent to a 40mm on a 4bt. It should be equivalent in spool up time and longevity etc. Also, ball-bearing turbos have less friction compared to conventional turbos, so spool-up(full boost) is quicker. I have not had the chance to test various trim turbos, so this is all theory. If a well working 6bt compound setup is using a 60mm/90mm; then a 4bt should easily use a 40mm/60mm turbo setup, which is 2/3rds the size of the 6bt, because the 4bt has 2 less cylinders.

Please correct me(with proof) if I'm wrong guys. Thanks, Bradley
Click to expand...

sorry, it doesn't work that way. You are looking for 2/3 the flow not 2/3 the wheel diameter.
 
I would use nothing smaller than a 66/73 as the primary charger on a 4bt twin set.
 
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