Kenne Bell 2.8 on 402/AFR 225/Long Tube- H2
04-21-2007, 11:52 AM
#53
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Originally Posted by dirt_track_racer_81
sorry didnt read the whole thread and it could be posted but what did you do with your edelbrock set up?
04-21-2007, 12:54 PM
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Timing vs IAT @ Boost level
I've had some time now to experiment with the KB 2.8 a little bit as far as timing goes. It's yielded some interesting observations.
As some may recall waaaaaaay back in 2005 Zippy and I were both experimenting with ways to get more timing in the Radix package once it had the 2.75 pulley installed. It was a real battle with IAT's climbing to the 170 degree range. The higher IATs went the less boost was allowed before knock took away the timing. Zippy and I were both running a tricky system using the main timing table and the IAT timing table to get more timing in the low gears (before the IAT's climbed) and then it scaled back in second gear as temps maxed out. This worked pretty well...but as I recall I was never able to run more than 19-20 degrees for part of 1st gear only. Second gear and third gear were more like 17-18 degrees max.
The Kenne Bell is able to run 23 degrees of timing on my truck across the board at wide open throttle with about 9 psi boost so far. Regardless of reported IAT readings. This tends to support the idea that IAT's as we see them are not true readings and not comparable across supercharger brands. There is also an efficiency component to the Timing vs IAT @ Boost Level.
Obviously, we've known that IATs reported have a lot to do with case temperature of the compressor. I assume that IATs are located on the case solely because the stock style IAT sensors are cheap and it is certainly safer to base engine operations that reference IAT on the hotter of your two choices - ambient IAT or the higher compressor case IAT. Clearly ambient readings could have catastrophic consequences whereas the compressor case simply would result in less performance. It just makes sense from the company standpoint to put something out that runs safer and limits potential warranty issues/returns.
Anyway... my Kenne Bell install is running 100-115 compressor case IATs with 50-60 degree ambient temps. A run up to 90-100 mph results in temps of about 160 to 170 degrees reported on the compressor case at about 9 psi boost level. Once off the boost IAT case temps drop right back to ambient in about a minute or so. A shorter time than it takes to go back to the staging lanes if you were at the track
Bear in mind this is a 402 with headers and AFR heads. It takes a lot more air to make 9psi (restriction) on this than the last stock LQ4 with only a cam and springs with stock exhaust manifolds.
Heres another intersting observation to consider on this topic... The IATs reported from the compressor case are virtually the same as when I was running the 6 psi set up on this blower. Maybe 10 degrees higher after a run to 90 mph. That also is not consistent with the way we saw IATs climb on the radix as boost was increased. A 3 psi change in boost on the radix was not a simple 10 degree gain in IAT... and it didn't recover as quickly. I clearly remember driving out the gate after a drag strip run and cruising about 2 miles and turning around to come back to the drag strip in an effort to get IATs back down to the minimum so I could "hot lap" at the strip. The Kenne Bell doesn't require that in my observation.
So.... it seems to me that compressor efficiency is the explanation of the difference in timing allowed vs IAT @ Boost level. At 9si on a 6.0 the Radix may not have been out of air... but it was well out of its efficiency range and that made the case temps or "IATs" run high and kept timing quite a bit lower than I can run now. On the KB 2.8 the case temp is higher (it is a lot bigger, too) but it can flow so much more air that it isn't really heating up the real air inside as much as the radix did. This allows much more timing ... again 23 degrees so far... with no knock whatsoever at temps that the radix would have knocked all over.
I've called this a "paradigm shift" in personal conversation and it certainly makes you look at the IAT topic differently. Tring to compare performance based on compressor case IAT's across brands like the Radix and Kenne Bell or thewhipple for that matter is useless. Looking at IATs will help you develop a radix package for your vehicle. Or you can look at IATs to develop you Kenne Bell package. But the two do not compare across brands. The airflow is the big difference and is easily overlooked.
As some may recall waaaaaaay back in 2005 Zippy and I were both experimenting with ways to get more timing in the Radix package once it had the 2.75 pulley installed. It was a real battle with IAT's climbing to the 170 degree range. The higher IATs went the less boost was allowed before knock took away the timing. Zippy and I were both running a tricky system using the main timing table and the IAT timing table to get more timing in the low gears (before the IAT's climbed) and then it scaled back in second gear as temps maxed out. This worked pretty well...but as I recall I was never able to run more than 19-20 degrees for part of 1st gear only. Second gear and third gear were more like 17-18 degrees max.
The Kenne Bell is able to run 23 degrees of timing on my truck across the board at wide open throttle with about 9 psi boost so far. Regardless of reported IAT readings. This tends to support the idea that IAT's as we see them are not true readings and not comparable across supercharger brands. There is also an efficiency component to the Timing vs IAT @ Boost Level.
Obviously, we've known that IATs reported have a lot to do with case temperature of the compressor. I assume that IATs are located on the case solely because the stock style IAT sensors are cheap and it is certainly safer to base engine operations that reference IAT on the hotter of your two choices - ambient IAT or the higher compressor case IAT. Clearly ambient readings could have catastrophic consequences whereas the compressor case simply would result in less performance. It just makes sense from the company standpoint to put something out that runs safer and limits potential warranty issues/returns.
Anyway... my Kenne Bell install is running 100-115 compressor case IATs with 50-60 degree ambient temps. A run up to 90-100 mph results in temps of about 160 to 170 degrees reported on the compressor case at about 9 psi boost level. Once off the boost IAT case temps drop right back to ambient in about a minute or so. A shorter time than it takes to go back to the staging lanes if you were at the track
Bear in mind this is a 402 with headers and AFR heads. It takes a lot more air to make 9psi (restriction) on this than the last stock LQ4 with only a cam and springs with stock exhaust manifolds. Heres another intersting observation to consider on this topic... The IATs reported from the compressor case are virtually the same as when I was running the 6 psi set up on this blower. Maybe 10 degrees higher after a run to 90 mph. That also is not consistent with the way we saw IATs climb on the radix as boost was increased. A 3 psi change in boost on the radix was not a simple 10 degree gain in IAT... and it didn't recover as quickly. I clearly remember driving out the gate after a drag strip run and cruising about 2 miles and turning around to come back to the drag strip in an effort to get IATs back down to the minimum so I could "hot lap" at the strip. The Kenne Bell doesn't require that in my observation.
So.... it seems to me that compressor efficiency is the explanation of the difference in timing allowed vs IAT @ Boost level. At 9si on a 6.0 the Radix may not have been out of air... but it was well out of its efficiency range and that made the case temps or "IATs" run high and kept timing quite a bit lower than I can run now. On the KB 2.8 the case temp is higher (it is a lot bigger, too) but it can flow so much more air that it isn't really heating up the real air inside as much as the radix did. This allows much more timing ... again 23 degrees so far... with no knock whatsoever at temps that the radix would have knocked all over.
I've called this a "paradigm shift" in personal conversation and it certainly makes you look at the IAT topic differently. Tring to compare performance based on compressor case IAT's across brands like the Radix and Kenne Bell or thewhipple for that matter is useless. Looking at IATs will help you develop a radix package for your vehicle. Or you can look at IATs to develop you Kenne Bell package. But the two do not compare across brands. The airflow is the big difference and is easily overlooked.
Last edited by CHarris; 04-21-2007 at 01:01 PM.
04-22-2007, 01:36 PM
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Cory and others.
Got a pic of where the IAT is on this setup? We have one car that never really see's a IAT change even at 14Psi boost. Then it getts heat soaked and some times takes a while to cool off.
Turns out to be the way the IAT is mounted and the lack of good air OVER the IAT.
Food for thought
Got a pic of where the IAT is on this setup? We have one car that never really see's a IAT change even at 14Psi boost. Then it getts heat soaked and some times takes a while to cool off.
Turns out to be the way the IAT is mounted and the lack of good air OVER the IAT.
Food for thought
04-23-2007, 07:15 PM
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Placed my order for cutouts last night. Looks like I'll be installing two of them. I blew my exhaust open the other day... lol This was between the cats and the Corsa. The slip fit joint came apart and is now not able to slip fit at all. The pipes are now the same size... 
If theres that much restriction after the cats... then it must be pretty strong before the cats as well.
I KNEW I needed 1 7/8 headers with 3 inch collectors... damn.
If theres that much restriction after the cats... then it must be pretty strong before the cats as well.
I KNEW I needed 1 7/8 headers with 3 inch collectors... damn.
04-24-2007, 02:16 AM
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Originally Posted by TwoFast4Lv
Cory and others.
Got a pic of where the IAT is on this setup? We have one car that never really see's a IAT change even at 14Psi boost. Then it getts heat soaked and some times takes a while to cool off.
Turns out to be the way the IAT is mounted and the lack of good air OVER the IAT.
Food for thought
Got a pic of where the IAT is on this setup? We have one car that never really see's a IAT change even at 14Psi boost. Then it getts heat soaked and some times takes a while to cool off.
Turns out to be the way the IAT is mounted and the lack of good air OVER the IAT.
Food for thought
http://www.ls2portworks.com/images/k...ll_2.8_037.jpg
04-24-2007, 08:59 AM
#59
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I have been reading this as you post along and was waiting anxiously before you even posted about the blower to see what you were going to have for a setup. I certainly feel that you picked a killer setup for what you needed. I also agree about the IAT issue. When the blower is actually big enough for it's use, it isn't just a heat pump.
04-25-2007, 07:30 PM
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Originally Posted by zippy
I have been reading this as you post along and was waiting anxiously before you even posted about the blower to see what you were going to have for a setup. I certainly feel that you picked a killer setup for what you needed. I also agree about the IAT issue. When the blower is actually big enough for it's use, it isn't just a heat pump.
Zippy you're alive! Glad to see you/read you again. This ones gonna be fun to dial in. I think you could have a good time with one of these tuner kits
I received my cut outs today. I went with "Dougs" they have a slide instead of a butterfly. This will definitely hold up to the heat and exhaust pressure. Summit lists them for $599 a pair.. .but a smart shopper checks Jegs and makes Summit match it. Jegs lists for $560
I'm waiting on one back ordered part. My QTP 304 stainless cut out pipe. This will be inserted into my exhaust so the Dougs cut-out has a nice place to bolt onto. I'll probably get these installed in early to mid May.