Twin scroll questions
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On The Tree
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Twin scroll questions Got a good deal on a hx40 wondering if it is worth all the pipe to utilize the twin scroll properly and that is going to.require two waste gates if I'm not mistaken. Anyone want to chime in
On The Tree
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I think typically it might spool a few hundred rpm earlier, I don't think most v8 guys bother.
However, are you planning to use this on a LS engine? Those turbos would typically be sized more for a 2 liter to 3 liter gas engine. Two of them might do the trick but then it gets more expensive and complicated. I have experience with a similar turbo (HE351CW) on a 2.4 and it was just about right.
If you plan on boosting a v8 on the cheap I would use an Ebay GT45 or for a few bucks more an ebay 7875.
https://www.ebay.com/itm/153895166446
https://www.ebay.com/itm/164386150148
However, are you planning to use this on a LS engine? Those turbos would typically be sized more for a 2 liter to 3 liter gas engine. Two of them might do the trick but then it gets more expensive and complicated. I have experience with a similar turbo (HE351CW) on a 2.4 and it was just about right.
If you plan on boosting a v8 on the cheap I would use an Ebay GT45 or for a few bucks more an ebay 7875.
https://www.ebay.com/itm/153895166446
https://www.ebay.com/itm/164386150148
HX40’s came in a dozen difference configurations. None of them pair well with a “v8” IMO. You’d need the wheels sizes and the exh housing size to determine if it would even be useable. Largest COMP wheel Holset made was 60mm (most are 58 or smaller) That’s pretty darn tiny for any LS. Then they usually came with huge Exh. housings. Looks at the CM it AR conversion charts on google. You’d be much better off with the cheap ebay 78/75’s.
You can’t configure a v8 to work with a twin scroll properly… (unless you have 180* headers). Otherwise, you can’t properly divide the exh pulses. Twin scrolls are made for 4 and 6 cyl setups that you can properly divide the exhaust pulses. They don’t work as designed on a v8. Theres little to no benefit/difference between a twin and a open scroll on a V8.
You can’t configure a v8 to work with a twin scroll properly… (unless you have 180* headers). Otherwise, you can’t properly divide the exh pulses. Twin scrolls are made for 4 and 6 cyl setups that you can properly divide the exhaust pulses. They don’t work as designed on a v8. Theres little to no benefit/difference between a twin and a open scroll on a V8.
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On The Tree
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Next question was where do you put the 02 sensors in a true split system(w/180* headers) but sounds like it might be a waste of time. I would think the throttle response would be nice and make boost down low wouldn't it? It is a 7 blade comp wheel if that makes a difference. I was told it is good for 750-800 hp but again it sounds like I'm getting bad info.
The blade count/spacing/angle etc all make a differnece. But you don’t have enough infomration to really make a comparison. An hx40 will not make that kind of power as a single on any v8.
They can make great power on smaller motors. Even then, 700+ is a stretch. I ran a modified HX40 on my 2 liter at 36lbs. Great little turbo… but unless you want to run them in twin configurations with small exhaust housings, they aren't large enough for an LS.
If you want a cheap turbo, I’d call up VSR and talk to them. Tell them what you want and ask what unit to run. I bet you walk away with a 78/75 of some sort. Great entry level budget turbo that checks most boxes.
They can make great power on smaller motors. Even then, 700+ is a stretch. I ran a modified HX40 on my 2 liter at 36lbs. Great little turbo… but unless you want to run them in twin configurations with small exhaust housings, they aren't large enough for an LS.
If you want a cheap turbo, I’d call up VSR and talk to them. Tell them what you want and ask what unit to run. I bet you walk away with a 78/75 of some sort. Great entry level budget turbo that checks most boxes.
Last edited by Forcefed86; Jan 3, 2024 at 03:47 PM.
On The Tree
Joined: Oct 2012
Posts: 198
Likes: 33
Next question was where do you put the 02 sensors in a true split system(w/180* headers) but sounds like it might be a waste of time. I would think the throttle response would be nice and make boost down low wouldn't it? It is a 7 blade comp wheel if that makes a difference. I was told it is good for 750-800 hp but again it sounds like I'm getting bad info.
Can you get an identical one and do a twin turbo system? Holsets are good turbos and will light off quick with two and appropriately sized turbine housings. However, personally I would sell the HX40 and get the ebay 7875 with .96ar. Should make great power from 3000rpm to redline on a 5.3 liter and instant boost on a 6 liter.
Or if you want to do it cheaper and easier, nitrous works great if you use proper precautions and some restraint.
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