Pathetic 427 numbers...help!
09-17-2007, 11:26 AM
#21
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I hope it's something simple like happened to me. I had a cracked plug after the Dynatech headers were installed while still SI. I was down 40-50 horsepower on the dyno. I thought, "Oh crap, these headers are too big for SI and have killed my power." While idling the bad plug would fire. Just under a load did it break down and only run on 7 cylinders. It still felt and sounded OK while driving around. It was just way weaker than I thought it should have been. It WAS weaker than it should have been. Found the cracked plug, changed it, the power obviously came back and it was a whole different animal. I hope your problem is something so simple as that. Good luck.
09-17-2007, 12:10 PM
#23
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That TQ curve start far earlier then a factory LS7 intake really should. The power curve is also very short. That engine should not start falling off till at least 6400 or higher. Cam timming. Somethings wrong here. I am thinking its in very early.
Originally Posted by Patrick G
Your curves suggest proper cam timing. Either the dyno had a screwed up weather correction or you're down 1 cylinder. With your tuning software, start turning off cylinders to see if you have a dead hole. My guess is you're not getting spark to one cylinder. 482/7 = 68.9 rwhp/cylinder (if you're down 1). A full 8 cylinders would give you 551 rwhp which is about where you should be.
09-17-2007, 03:57 PM
#25
im not saying this is your problem but every ls1 in rx7's ive seen so far have dynoed low, idk if its anything in the drivetrain dynamics that is causing a problem but the ones i dynoed were down over 10 percent in power for each application
09-17-2007, 03:57 PM
#26
Originally Posted by LS1curious
That TQ curve start far earlier then a factory LS7 intake really should. The power curve is also very short. That engine should not start falling off till at least 6400 or higher. Cam timming. Somethings wrong here. I am thinking its in very early.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
LS1,LS2,LS3,LS7,LT1 Custom Camshaft Specialist For custom camshaft help press here.
Custom LSX tuning in person or via email press here.
09-17-2007, 04:12 PM
#27
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actually they don't look like anything I am familair with as far as that intake goes. Usually power goes very flat at around peak TQ and stays that way till around 6500 or so. Thats a stock engine to.
Originally Posted by Patrick G
Power peak is at 6600 rpm and torque peak is at 5200 rpm which indicates sound valve events. The curves have the shapes as they should, they're just down altogether, like you're not firing one cylinder.
09-17-2007, 04:15 PM
#28
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Originally Posted by Patrick G
Power peak is at 6600 rpm and torque peak is at 5200 rpm which indicates sound valve events. The curves have the shapes as they should, they're just down altogether, like you're not firing one cylinder.
09-18-2007, 01:54 AM
#30
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Erik and Greg did the work on my motor. Very pleased! As for the break in time. I did the same as you and no issues at all. I made good power with my set-up! Before the beck intake I was 518rwhp 495TRQ! with my 408! Heads flowed there *** off!
09-18-2007, 05:06 PM
#32
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Sorry been too busy to post lately. Unfortunately, I may have to leave everyone hanging on this one. I'm leaving for Japan next Monday and have limited time to work on the car until then. When I leave, the car will be going into indoor government storage for three years (covered). It will be fired up once a month, driven to a new spot in the warehouse and any maintainance performed. I don't really have much of a choice here as the government of Japan wants $3-$5K to bring it into "compliance" and another $3-$5K when it would be due to come back to the states. I was also warned that I could have been hassled by the EPA on my return as well. *sigh*
Had I got an engine back in a reasonable time, I may have been able to do something about this. Not to knock Erik too bad, he's a nice guy and all, but the 14 month wait on the engine was a little ridiculous. What can ya do? :shrug:
I'll be sure to set a 2500RPM rev limit or something in the software before I leave the storage facility
As far as the ideas being tossed around:
Plugs & wires: I suppose I could go back to my old MSD's and another set of plugs. I inspected all of them for cracks once already. I don't think that's it but it's worth a shot.
LSx powered RX-7's dynoing low: Nothing in the drivetrain is Mazda except the hubs. T56 tranny, 03' Mustang 8.8 IRS out back (3.55 gearing), DSS Level 5 axles & CV's.
Leaning it out: Unless our wideband is WAY off, I can't see 1/2 a point equating to too much.
Dyno sucks: I don't think so. We run a number of cars on our dyno and most are "about right".
Temp gun: Great idea....not sure if I'll have time to find one though
Weather conditions: We're at sea level (50 ft, technically). According to weather.com for Sunday: 63°F, 58% humidity, 30.29 baro, uncorrected power was 502 RWHP. I'll have to double check the uncorrected torque reading.
I appreciate all the feedback though. I just wish I had more time to mess with it.
Ryan
Had I got an engine back in a reasonable time, I may have been able to do something about this. Not to knock Erik too bad, he's a nice guy and all, but the 14 month wait on the engine was a little ridiculous. What can ya do? :shrug:
I'll be sure to set a 2500RPM rev limit or something in the software before I leave the storage facility
As far as the ideas being tossed around:
Plugs & wires: I suppose I could go back to my old MSD's and another set of plugs. I inspected all of them for cracks once already. I don't think that's it but it's worth a shot.
LSx powered RX-7's dynoing low: Nothing in the drivetrain is Mazda except the hubs. T56 tranny, 03' Mustang 8.8 IRS out back (3.55 gearing), DSS Level 5 axles & CV's.
Leaning it out: Unless our wideband is WAY off, I can't see 1/2 a point equating to too much.
Dyno sucks: I don't think so. We run a number of cars on our dyno and most are "about right".
Temp gun: Great idea....not sure if I'll have time to find one though
Weather conditions: We're at sea level (50 ft, technically). According to weather.com for Sunday: 63°F, 58% humidity, 30.29 baro, uncorrected power was 502 RWHP. I'll have to double check the uncorrected torque reading.
I appreciate all the feedback though. I just wish I had more time to mess with it.
Ryan
09-19-2007, 10:50 AM
#35
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I was down 70hp on my 408 because my TB wasn't opening all of the way. I had the cable in the wrong hole on my Fast TB and it was only opening 2/3 of the way. We reconnected it to the bottom hole, adjusted the cable length and it picked up 72hp and 60tq.
09-19-2007, 04:29 PM
#37
Easiest way to tell that is via tuning software. If your throttle isn't reading 100% with the pedal to the metal... ding ding! And you can check that right now before you leave (even without software, just have someone watch the TB as you mash the pedal and see if they can open it any further)! Don't leave us hanging on that one!
09-19-2007, 09:36 PM
#39
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Please do yourself a favor and temperature check the exhaust primaries with a temp gun. But I know you're low on time. To me it would be worth the cost to have the only badass ls1 in japan, but im hardcore like that. good luck and thanks for serving the country. we really appreciate you and what you do.
Wes
Wes
