posted
I need some suggestions. Last July (July 2001) I had my 2000 SS dyno'd on a DynoJet dynomometer, with the following results: SAE corrected 329.3 rwhp, 332.4 rwtq, air-fuel ratio average = 12.7. Yesterday, June 1, I had the car dyno-tested also using a DynoJet machine, with the following results: 318.3 rwhp (also SAE corrected), 327.0 rwtq; air-fuel ratio average = 13. We're looking at a net SAE horsepower loss of 11 rwhp, which is more than can be attributed to the difference between two DynoJet apparatuses, I believe. The following power mods were in place for both sets of pulls: SLP LM exhaust, SLP Y-pipe, SLP stainless cold air pickup, SLP 85mm MAF, Direct-Flo airlid. The engine, MN6 transmission and real axle were in both cases filled with Red Line synthetic lubricants. Additional mods and/or new parts in place for yesterday's dyno run were as follows: Baker hose, throttle body coolant bypass, NGK TR55 plugs gapped to .055, new MSD plug wires, and stock Corvette fuel rail covers cut to fit the Camaro engine compartment (can't see any effect there because the hood was wide open for the dyno run). Also, for yesterday's run, the Holley Powershot air filter (in place for the July 2001 pulls) was removed entirely, and the intake manifold was cooled with ice bags for around 1-1/2 hours before the pulls. As of yesterday, the car had a little over 39,000 miles on the odometer, approximately 10,000 miles more than last July. I was expecting a small power increase from the combination of new Baker hose, TB bypass and no air filter, rather than a power loss. Any ideas where my missing 11 horses went? (Someone suggested my cats might be solidifying, for example...) All thoughts welcome-- thanks!
-------------------- Paul Zink, Chicago, IL. SSOA Member #M00-1181; 2000 Camaro SS, SLP No. 1181, Light Pewter, M6, T-Tops, all options. [bMODS and UPGRADES: [/b] Direct-Flo lid, SLP cold air box, Shaner S2, MBA MAF ends, JBA headers, SLP Loud Mouth exhaust, Y-Pipe, SuperTrapp mufflers, SLP Eibach-Bilstein suspension, Addco 32mm/22mm solid swaybars, PST bushings, TByrne LCAs & Panhard Rod, BMR LCA relocation brackets, SLP Shock Tower Brace, SFCs, Richmond 3.73 gears, B & M shifter, SLP TCS Reversal, TA Performance diff cover, Random Technology Torque Arm, PowerSlot rotors, Earl's lines, 160 Thermostat, Red Line Oil, SLP “SS” grille, mats, dash plaque, key fobs, “SS” deck lid mat, MBA pedals, White-face gauges, burlwood interior, Wheelskins shifter boot and wheel cover, custom Fuel Rail Covers, Aluminum sill covers.
Dyno Results from Sept 14, 2003: 328.1 RWHP Photo below: Getting ready for Halloween Car show, Oct. 2001
posted
I think there could be that much difference in Dyno's. I don't see any other reason that there could be a difference.
Posts: 5946 | From: Litchfield, NH, USA | Registered: Feb 2000
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quote:Originally posted by DanA_F99_1977: I think there could be that much difference in Dyno's. I don't see any other reason that there could be a difference.
Dan, that's a 3.4% difference -- you think that much is likely? Dean at New England dyno was puzzled by the loss, and I'd think he would be the first to write it off as permissible machine variation if it was a usual occurrence, no?
Posts: 83 | From: Chicago, IL | Registered: Mar 2000
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posted
A couple of thoughts: Your first pull seems high. Assuming approx. 300 HP base, you should expect approx. 10 HP for the LM and Y pipe, and 10 for the lid and holley filter. Results have been mixed for the 85mm MAF but it is generally for modified engines requiring more air (heads, cam, headers, etc.) So it would seem that you should have been at about 320.
Removing the airfilter may have affected the PCM with not enough time to adjust.
Did you knock anything loose (vacuum line) doing the FRCs?
Does it feel weaker - I know that's hard to tell but did anything feel any different after any of the additional mods?
Just some thoughts, and finally, don't worry about it, continue with your mods!
Posts: 3403 | From: Woodcliff Lake, NJ, USA | Registered: Dec 2000
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Dan, that's a 3.4% difference -- you think that much is likely? Dean at New England dyno was puzzled by the loss, and I'd think he would be the first to write it off as permissible machine variation if it was a usual occurrence, no?
Good point Paul. Dean is a good guy and I am sure would have suggested it. Too bad I wasn't there. I have a dyno run from a different machine that says 325. It would have been interesting to see what Dean's would have given me.
Any way you could have taken off some of the latest mods and tried again. I know it's hindsight but would have been interesting. Are you happy with the car still? If so, I wouldn't let the dyno runs bother me too much.
Posts: 5946 | From: Litchfield, NH, USA | Registered: Feb 2000
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posted
Also, you stated that the first time you were 12.5 A/F, and the last time you were at 13.0 A/F ratio. That actually is quite a bit leaner, which could explain the loss, if in fact you have one. Just my .02 cents worth!
quote:Originally posted by DaddySS: A couple of thoughts: Your first pull seems high. Assuming approx. 300 HP base, you should expect approx. 10 HP for the LM and Y pipe, and 10 for the lid and holley filter. Results have been mixed for the 85mm MAF but it is generally for modified engines requiring more air (heads, cam, headers, etc.) So it would seem that you should have been at about 320.
Removing the airfilter may have affected the PCM with not enough time to adjust.
Did you knock anything loose (vacuum line) doing the FRCs?
Does it feel weaker - I know that's hard to tell but did anything feel any different after any of the additional mods?
Just some thoughts, and finally, don't worry about it, continue with your mods!
Don't forget the SLP Cold Air Pickup in place for both sets of pulls; that also should be worth a few rwhp, making the 329 reading more realistic. As for the FRCs, I don't think anything got knocked loose, as I carefully cut away large portions in the rear to clear all the lines and tubing; also, I think I would have felt a difference on the road by now (I installed them in late August 2001). Thanks for the encouragement about continued mods --this sort of problem works itself out eventually.
Posts: 83 | From: Chicago, IL | Registered: Mar 2000
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