Which would produce more towing power?
09-30-2007, 09:30 AM
#11
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I'm going the 408 route and a relatively small cam (going back to my 212/218 @ 114 LSA) for simplicity and durability reasons and I'm going to run 9.5:1 CR so that I can use 87 Octane.
Although I believe that the Radix is the best forced induction option for what you want to do, I've driven the Radix in a Silverado SS and the way it is set up, the the blower bypass valve closes at about 60 to 75 percent throttle travel and BAM it's alive and kicking. With towing, there are many times that you need excellent torque at 30 to 50 percent throttle. Also, if you plan to keep the truck over the next six years or so and minimize the maintenance, normally aspirated is going to be the way to go.
These are just my thoughts.
Steve
Although I believe that the Radix is the best forced induction option for what you want to do, I've driven the Radix in a Silverado SS and the way it is set up, the the blower bypass valve closes at about 60 to 75 percent throttle travel and BAM it's alive and kicking. With towing, there are many times that you need excellent torque at 30 to 50 percent throttle. Also, if you plan to keep the truck over the next six years or so and minimize the maintenance, normally aspirated is going to be the way to go.
These are just my thoughts.
Steve
09-30-2007, 09:42 AM
#12
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Is this true? I have to wait till I am giving 60 to 75% throttle for the Radix to kick in? If that's the case I agree that is not good for towing and would actually cause you to burn more fuel.
Originally Posted by Steve Bryant
I'm going the 408 route and a relatively small cam (going back to my 212/218 @ 114 LSA) for simplicity and durability reasons and I'm going to run 9.5:1 CR so that I can use 87 Octane.
Although I believe that the Radix is the best forced induction option for what you want to do, I've driven the Radix in a Silverado SS and the way it is set up, the the blower bypass valve closes at about 60 to 75 percent throttle travel and BAM it's alive and kicking. With towing, there are many times that you need excellent torque at 30 to 50 percent throttle. Also, if you plan to keep the truck over the next six years or so and minimize the maintenance, normally aspirated is going to be the way to go.
These are just my thoughts.
Steve
Although I believe that the Radix is the best forced induction option for what you want to do, I've driven the Radix in a Silverado SS and the way it is set up, the the blower bypass valve closes at about 60 to 75 percent throttle travel and BAM it's alive and kicking. With towing, there are many times that you need excellent torque at 30 to 50 percent throttle. Also, if you plan to keep the truck over the next six years or so and minimize the maintenance, normally aspirated is going to be the way to go.
These are just my thoughts.
Steve
09-30-2007, 10:13 AM
#13
The bypass is set at 2in VAC and will close INSTANTLY once that vacume reference is gone. I am not sure what steve is describing, sounds like there might have been an issue with that set up. Bolting on a Radix is the equivalent of dropping in a big block. Once the bypass loses vacume (engine is under load) the valve is closed and boost is produced. This is evident in the dyno graphs.
With well over 75,000 miles on the company tow rig and a 19K trailer.....and not ONE issue with the 2500 HD, I think the FI option is the only way to go.
I dont think there is one person here that can compare the opportunity / cost of time of installing a Radix vs. a new motor.
Install the blower, leave it alone (just as it comes outta the box) and enjoy the performance.
With well over 75,000 miles on the company tow rig and a 19K trailer.....and not ONE issue with the 2500 HD, I think the FI option is the only way to go.
I dont think there is one person here that can compare the opportunity / cost of time of installing a Radix vs. a new motor.
Install the blower, leave it alone (just as it comes outta the box) and enjoy the performance.
09-30-2007, 10:15 AM
#14
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Vince,
That was my perception. I sent a queston to Eaton on the technical portion of their website a number of months ago asking if there were options for controlling the bypass valve in a progressive/graduated manner and they've never replied. Maybe some folks who have the Magnuson/RADIX will chime in about this.
Steve
That was my perception. I sent a queston to Eaton on the technical portion of their website a number of months ago asking if there were options for controlling the bypass valve in a progressive/graduated manner and they've never replied. Maybe some folks who have the Magnuson/RADIX will chime in about this.
Steve
09-30-2007, 10:21 AM
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Blown Chevy, I must have been typing when your post popped up.
It's this all or nothing boost that I'm talking about. For instance if you blocked the throttle travel off at 40 percent travel, would the boost start to come in or would it come in later, all at once? I don't think so. A standard sea level day has an atmospheric pressure of 29.92" Hg. Let's say that at WOT, the manifold absolute pressure (MAP) is roughly 28" Hg. The RADIX wont come alive until about 26" Hg and then it's going great guns . . . even off idle.
I agree that at WOT, the RADIX is better than a big block under certain conditions. However, for serious towing, part throttle torque is more useful than at or near WOT.
Thanks,
Steve
It's this all or nothing boost that I'm talking about. For instance if you blocked the throttle travel off at 40 percent travel, would the boost start to come in or would it come in later, all at once? I don't think so. A standard sea level day has an atmospheric pressure of 29.92" Hg. Let's say that at WOT, the manifold absolute pressure (MAP) is roughly 28" Hg. The RADIX wont come alive until about 26" Hg and then it's going great guns . . . even off idle.
I agree that at WOT, the RADIX is better than a big block under certain conditions. However, for serious towing, part throttle torque is more useful than at or near WOT.
Thanks,
Steve
Last edited by Steve Bryant; 09-30-2007 at 10:33 AM.
09-30-2007, 10:24 AM
#16
Originally Posted by Steve Bryant
Vince,
That was my perception. I sent a queston to Eaton on the technical portion of their website a number of months ago asking if there were options for controlling the bypass valve in a progressive/graduated manner and they've never replied. Maybe some folks who have the Magnuson/RADIX will chime in about this.
Steve
That was my perception. I sent a queston to Eaton on the technical portion of their website a number of months ago asking if there were options for controlling the bypass valve in a progressive/graduated manner and they've never replied. Maybe some folks who have the Magnuson/RADIX will chime in about this.
Steve
I can produce 5 psi at 30% TPS pulling a trailer up the hills.
09-30-2007, 12:39 PM
#17
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Originally Posted by BlownChevy
Good luck with getting that reply LOL. You need to remember that the vacume of the engine is in dependent on engine load. In the case of the SSS, more than likely there was not enough load to require the bypass valve to close any sooner than what you observed. Put a trailer behind that SSS (more load) and the results would be different.
I can produce 5 psi at 30% TPS pulling a trailer up the hills.
I can produce 5 psi at 30% TPS pulling a trailer up the hills.
09-30-2007, 02:25 PM
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TBSS, that's right. I'd like to see it work proportionally.
Blown Chevy, as I recall, you went back to work at Magnuson last month. Here's a couple of ideas you might ask them consider:
1. Have a BYPASS OVERRIDE switch so that for towing the supercharger is boosting the induction system all of the time. This way it is proportional to engine speed. For normal operation, the servo diaphragm would activate on the 2" Hg vacuum differential. The operator gains a feature and it's easy to implement.
2. Offer an 87 Octane tune. This probably means just remapping the spark tables.
Steve
Blown Chevy, as I recall, you went back to work at Magnuson last month. Here's a couple of ideas you might ask them consider:
1. Have a BYPASS OVERRIDE switch so that for towing the supercharger is boosting the induction system all of the time. This way it is proportional to engine speed. For normal operation, the servo diaphragm would activate on the 2" Hg vacuum differential. The operator gains a feature and it's easy to implement.
2. Offer an 87 Octane tune. This probably means just remapping the spark tables.
Steve
09-30-2007, 06:16 PM
#19
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Has anyone ran a 408ci and Radix? Actually can the Radix even support a 408ci in a truck application? I would think the tq would be somewhere in the 600+ range..
09-30-2007, 06:22 PM
#20
Originally Posted by VINCE
Has anyone ran a 408ci and Radix? Actually can the Radix even support a 408ci in a truck application? I would think the tq would be somewhere in the 600+ range..
Magnuson has a very nice tow setup for the LQ4