Anyone done any testing with an lly turbo on how much boost it will make with the vanes all the way open? Just curious as the way i have the vanes tuned just want to know how much boost the 4202 is making. If someone knows I can figured it close enough. Thanks!
Lly turbo
- Thread starter SteveFord
- Start date
No drive pressure guage and have no plans really to get one. Opening them up from testing by going by my egts is telling me its breathing better and the 4202 is producing more boost this way. What I'm trying to do is make the 4202 do most of the work at wot at a certain rpm and boost as the vanes open up all the way allowing as much exhaust as possible to go by the stocker and drive the big charger. Drivabilty of twins but at wot act more like a big single as much as I can.
If you are running the stock VNT charger a drive psi gauge is a must for tuning in my opinion.
I've seen 100+psi of drive on 40psi of boost. Scary numbers.
I've seen 100+psi of drive on 40psi of boost. Scary numbers.
I'd guess something is limiting your vanes from going to 0%. You wouldn't ever be able to make that much boost with the vanes at 0%.
Hypothetically speaking...if the turbo was tight enough, and you were essentially bypassing the stock charger, I guess it would act like a big laggy single.
Is that what you were asking?
Is that what you were asking?
In a way yes! It acts like twins should driving around and towing. I'm trying to make sure it still spools fast enough from a dig but then the stocker opens up and the big charger does the majority of the work. They way I have it now is if everything is right as far as boost, at 2600 the vanes open up.
Ideally, a compound setup works where the small charger does all the work down low and then gradually gets aided by the larger charger. There is a reason the big charger in a compound setup is called the 'low pressure charger,' because it flows big CFM at low psi.
Understand that. Has anyone tried to do what I'm doing to see if that works also? Thats the reason I was wondering what an lly turbo makes for boost with the vanes fully open.
I have been wondering the same thing. If I was to build a tune for a compound setup I would open up the vanes as the big charger lit up.
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This is what I'm seeing on a very mild tune.
60psi boost
28psi boost out of the s480
100 psi drive pressure could be more idk it only go's to a 100.
Idk if that help you but it can give you something to think about.
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60psi boost
28psi boost out of the s480
100 psi drive pressure could be more idk it only go's to a 100.
Idk if that help you but it can give you something to think about.
Sent from my iPhone using Tapatalk
Thats a ton of drive pressure but then again your also seeing 60psi on a mild tune. Other guys I know that have tested drive with the mpi kits see close to a 1:1-1.5 but as they get above 3400rpm it starts to jump up. It's tuff to compare a totally different kit from another and tuning that isn't the same also.
I've been told that it's high but the truck is really responsive it builds boost incredibly fast like Instantly but I think that's due to the race cover on the s480.
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Yes Steve, you are going about it the right way. It will depend on the amount of fuel in the tuning also but I run my vanes at 0% above 2600rpms and I have 56psi boost total and 65psi drive until I get upstairs and then the drive will climb to 80psi at 4500rpms but I can back that down with the gate.