cardo0
Dyno vid, my 78
Thread Starter
Race Director
Joined: Jan 2000
Posts: 12,399
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From: San Jose CA
Dyno vid, my 78
http://students.engr.scu.edu/~sbeeby/dyno_78.wmv
Car made 241 rwhp, 283 rwtq. Not quite what I was hoping for. A/F dropped to about 12:1 at 3800 rpm and stayed low all the way up to 6200 rpm.
I can't believe they ran the engine that high. Holy crap.
Where to go from here...?
-Steve
Car made 241 rwhp, 283 rwtq. Not quite what I was hoping for. A/F dropped to about 12:1 at 3800 rpm and stayed low all the way up to 6200 rpm.
I can't believe they ran the engine that high. Holy crap.
Where to go from here...?
-Steve
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
why do you suppose the torque was so low? the HP seems respectable.... especially if you need to adjust it some . i'm just surprised at the torque #s????? and i bet it screams with that 700r4 in it.
Thread Starter
Race Director
Joined: Jan 2000
Posts: 12,399
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From: San Jose CA
I'm not sure. The A/F ratio didn't get really rich until about 4300 rpm, where it dipped down to 12:1. Wonder if the intake just shuts down at that point.
Maybe I should find someone to beef up an EGR performer...
-Steve
Maybe I should find someone to beef up an EGR performer...
-Steve
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
how do you know your timing is right? especially the vacuum advance portion? could you be hitting a "timing issue" at that RPM also?
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Thread Starter
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Vac advance should be shut off on the dyno, no? I thought you get 0 vac advance at WOT. Timing is a good thing to play with though... I'll think about it. That could very well be why the torque is so low.
-Steve
-Steve
Melting Slicks
Joined: Jan 2003
Posts: 2,804
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From: OKC Oklahoma
hey dude, i'd completely expect substantially higher numbers. how many pulls did you get and did you do any tuning. it's great that you posted the results. i think you have alot left in the tuning......
Thread Starter
Race Director
Joined: Jan 2000
Posts: 12,399
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From: San Jose CA
3 pulls, and they were consistent as hell. I mean, literally, you can barely see the three lines on the graph.
I had the carb scoped out by a local place. I really need to play with timing and jetting methinks.
-Steve
I had the carb scoped out by a local place. I really need to play with timing and jetting methinks.
-Steve
Melting Slicks
Joined: Feb 2004
Posts: 2,435
Likes: 0
From: largo florida
vacuum advance doesnt change anything at WOT like Pacin said. At WOT there is no vacuum so the advance unit will not advance timing any. Pacin, what rpm were your peak hp and tq at? How high did they run the engine on the dyno?
Race Director
Joined: Sep 2004
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by Pacin'California
Vac advance should be shut off on the dyno, no? I thought you get 0 vac advance at WOT. Timing is a good thing to play with though... I'll think about it. That could very well be why the torque is so low.
-Steve
-Steve
Burning Brakes
Joined: Nov 2003
Posts: 990
Likes: 0
From: North Texas
I checked your profile and see you already have the exhaust taken care of.... 
You may want to connect a pressure gauge to the exhaust just to verify it's performing. X or H pipe...
You could look at adding a carb spacer if there's hood clearence....
You may want to connect a pressure gauge to the exhaust just to verify it's performing. X or H pipe...
You could look at adding a carb spacer if there's hood clearence....
Pro
Joined: Oct 2004
Posts: 510
Likes: 5
From: Pipe Creek TX
I would pursue leaning the jetting if the density altititude was 2000 ft. or more. It could be worth 10-15 hp. Normally around 13:1 AF gives best power.
You are correct, play with total timing; you could be surprised.
You are correct, play with total timing; you could be surprised.
Melting Slicks
Joined: Apr 2000
Posts: 3,286
Likes: 8
From: San Jose California
Steve,
Considering that a factory L82 would only have made 180rwhp, perhaps less because of an automatic, 241 is very respectable. Especially considering that you are still only running a little more than 8:1 compression. Remember that most guys claiming high hp numbers are usually "out to lunch".
You are even making significantly more than a 72 LT1 which was/is a very potent motor. When you get the a/f sorted out you can probalby expect about another 10hp or so, but you still made some very good numbers! Your 0-60 numbers are very good.
Chuck
Considering that a factory L82 would only have made 180rwhp, perhaps less because of an automatic, 241 is very respectable. Especially considering that you are still only running a little more than 8:1 compression. Remember that most guys claiming high hp numbers are usually "out to lunch".
You are even making significantly more than a 72 LT1 which was/is a very potent motor. When you get the a/f sorted out you can probalby expect about another 10hp or so, but you still made some very good numbers! Your 0-60 numbers are very good.
Chuck
