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Original Message
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| 428 dyno results |
| By Paul Lovett - 03/12/2006 9:42:37 AM; IP 70.246.79.241 |
Dyno-ed my 428 yesterday. It was a DTS engine dyno that K&M Machine in Raytown, Mo just bought.
Motor spec's:
-432 cid (4.155"x3.98")
-850 double pumper (76/76 jets) milled choke horn
-Blue Thunder dual plane intake
-1" four hole spacer, 3-1/2" K&N filter
-Edelbrock heads (2.09"/1.66") ported to 303/218 cfm
-10.5:1 compression
-37 degrees total timing
-Solid flat tappet with 270/276 advertised duration, 240/246 @ 0.050", 108 LSA, 107 ICL, .598/.608" lift
-2" Crites headers
Final combo made 517 hp at 6200 rpm and 521 lb./ft. at 4200 rpm.
Initial pull was 484 hp and 512 lb./ft.
The biggest gains were from carb jetting and carb spacers. We started at 76/82 jetting, went to 80/82 and lost 10 hp. Went to 78/78 gained 5 hp. Went to 76/76 and gained 9 more hp. Based on BSFC numbers, we didn't want to go any leaner.
It liked taller spacers and liked the 4 hole best. We tried an open spacer and lost a few hp everywhere. We didn't rejet for the open spacer, though. Judging by the BSFC numbers, the open spacer leaned the mixture. We might've been able to get more hp out of it, but I like the 4 hole spacer for street driving so I didn't pursue it. Ended up gaining 2-3 hp and 10-12 lb/ft with the spacer I used.
The ignition timing happened to be right on the money (37 to 38 total) initially so I didn't gain anything there.
Didn't gain much varying valve lash. Tightening the lash a few thousandths would gain maybe 4-5 hp at high rpm and lose 4-5 hp at low rpm. No surprise there. I ended up using the Compcams recommendation of 0.0018" lash hot. That equals about 0.0013" lash cold with my aluminum heads.
Switching from 1-3/4" Hooker Supercomps to 2" Crites headers gained about 5 hp and 5 lb./ft. The bigger primaries on the Crites were balanced with significantly longer tubes so power gained everywhere. Honestly 1-7/8" might be the ideal tube diameter for my combo, but the 2" tubes work good and will allow for more hp in future. Plus the 3.5" collectors gave me an excuse to upgrade my exhaust system to 3.5" pipes and mufflers. :)
Switching to snythetic 20-50W oil from regular 20-50W oil got about 5-7 hp at the top end.
Total hp gain for the day was about 30 depending on what run we use for the baseline.
By the end of the day the torque at 3000 improved from 408 lb/ft to 456 lb/ft, and it passes 500 lb/ft at 3500 so it should be fun on the street.
Paul
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