L92 head 427 makes 700HP n/a!
06-26-2007 | 01:09 PM
#22
Originally Posted by HTMtrSprt
The engine is a 4.060" bore x 4.100" stroke piece built by someone else using a 6.0 cast iron block with 6.125" rods and flat top pistons. The heads and intake were already on the engine when it came in and due to time constraints I don't know how much they were milled but they were unported. We filled the intake runners and fully ported them along with filling and completely reshaping the runners and plenum in the fabricated intake. We then dyno'd the engine with the existing cam (248/258-114, .630/.630) and picked up MAJOR amounts of torque while making 5-10 more HP. Then we had our own cam ground and produced the listed results.
I believe the compression ratio is about 12:1 - my compression tests showed 210 PSI cranking, which is borderline for pump gas around here, but I tested it on Power 110 race fuel since the engine has no knock sensors.
I am new to posting images but I have my web guy putting up graphs on our web site and will make a post directing to them.... should be up sometime Tues. the 26th.
Becausing the block was a 6.0 iron instead of an LS2, it has no bay to bay windows in the main webs or passages above the pan rail which I believe would be worth even more power since the engine is so big and has only a stock F-car oil pan on it.
Headers used were our dyno units with 1 3/4"- 1 7/8" primaries to 3 1/2" collectors.
I believe the compression ratio is about 12:1 - my compression tests showed 210 PSI cranking, which is borderline for pump gas around here, but I tested it on Power 110 race fuel since the engine has no knock sensors.
I am new to posting images but I have my web guy putting up graphs on our web site and will make a post directing to them.... should be up sometime Tues. the 26th.
Becausing the block was a 6.0 iron instead of an LS2, it has no bay to bay windows in the main webs or passages above the pan rail which I believe would be worth even more power since the engine is so big and has only a stock F-car oil pan on it.
Headers used were our dyno units with 1 3/4"- 1 7/8" primaries to 3 1/2" collectors.
What were the numbers with modified heads & intake with the old cam?
06-27-2007 | 06:15 AM
#28
Originally Posted by HTMtrSprt
571 Tq/ 670 HP
Just so I understand all the info correctly the two graphs are with the epoxied heads and new cam, the only difference was the epoxied sheet metal intake vs. the epoxied L76 intake?
or
Are these graphs before and after all mods performed?
Do you have the numbers from the modified heads and intake with the old cam?
Finally, was the sheetmetal intake hot or cold during the runs?
Last edited by No Juice; 06-27-2007 at 07:43 AM.
06-27-2007 | 08:44 AM
#29
Thread Starter
FormerVendor
Joined: Jan 2002
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From: Mpls., MN
Originally Posted by No Juice
Just so I understand all the info correctly the two graphs are with the epoxied heads and new cam, the only difference was the epoxied sheet metal intake vs. the epoxied L76 intake?
Originally Posted by No Juice
Do you have the numbers from the modified heads and intake with the old cam?
Originally Posted by No Juice
Finally, was the sheetmetal intake hot or cold during the runs?
06-27-2007 | 09:19 AM
#30
Ok so that didn't make much sense but what I think you are saying is this
Original motor with stock L92 heads and sheetmetal = 661hp/555tq
Modified heads, modified sheetmetal intake and original cam = 670hp/571tq
Modified heads, modified L76 intake and new cam = 661hp/599tq
Modified heads, modified sheetmetal and new cam = 701hp/579tq
Nice job on the R & D work!!! Good to see some testing and comarisons. Thanks for showing results.
I wasn't implying that you iced the intake or anything like. I was just wondering if the sheetmetal was heat soaked for these runs? I've seen about 20-30 hp difference with a heat soaked intake, just curious thats all.
Original motor with stock L92 heads and sheetmetal = 661hp/555tq
Modified heads, modified sheetmetal intake and original cam = 670hp/571tq
Modified heads, modified L76 intake and new cam = 661hp/599tq
Modified heads, modified sheetmetal and new cam = 701hp/579tq
Nice job on the R & D work!!! Good to see some testing and comarisons. Thanks for showing results.
I wasn't implying that you iced the intake or anything like. I was just wondering if the sheetmetal was heat soaked for these runs? I've seen about 20-30 hp difference with a heat soaked intake, just curious thats all.
06-27-2007 | 04:32 PM
#33
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Joined: Mar 2003
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Originally Posted by Bink
257/264-114 .664/.644 - very streetable, in a large bore engine, with efi and a pcm. 
That is 32.5 degrees overlap at .050 lift...
427 or not it is going to reek of gas and idle is going to be a bear... vacuum is going to be crap at idle... but the people who would buy this type of setup probably do not care about those things anyway...
06-27-2007 | 06:37 PM
#34
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From: Mpls., MN
Originally Posted by triumphman
It is sure interesting watching this thread, heads full of epoxy and a cam that will barely run on the street for 30 more hp, not really worth it in my opinion.
06-27-2007 | 09:30 PM
#35
Teching In
Joined: Dec 2006
Posts: 49
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From: mn.
Clay don't make this personal. I spent $16,000 to $18,000 dollars and 2 years trying with you guys. We all knew I wanted 700hp. Brian spent 3 months and less than $1,000 dollars to reach this. They were willing to do the R&D almost for free.... It was 40 hp. more and 25 more ft.lbs tq. with a more usable power band. You know that, the cam is not that big. I just finished a 346 with a 240 244 cam idles at 900rpms it's all in the tune..
06-27-2007 | 10:18 PM
#37
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Originally Posted by HTMtrSprt
Maybe you're missing the customer's goal here...... In the words of Dr. Emmitt Brown, "It's a science experiment!"
06-28-2007 | 06:04 AM
#38
I was just looking at the charts again and I noticed the left bank hit amost 20:1 AFR a few times. Why is that? I don't know that much about tuning but I thought it should be around 13:1, more like the right bank. What causes the spikes?
06-28-2007 | 01:35 PM
#40
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From: Mpls., MN
Originally Posted by MoreJuice
Seems like a pretty expensive science project with $16-18,000 into it! Hope the epoxy holds.
As for the power curve, after the head and intake mods, the engine's torque curve was drastically widened and improved the average power under the curve. If you will note, the old peak tq occurred at 5900 while the improved heads lowered it to 5200 RPM while maintaining the peak hp RPM level. The tq at 4700 RPM was improved by 70 lb/ft! The engine also needed 2-3 degrees fewer ignition timing to make peak power. I would call that a sizeable difference in output from nothing more than an improvement in port velocity.