67 548" chassis dyno results
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Burning Brakes
Joined: Jul 1999
Posts: 922
Likes: 164
From: Hudson NH
67 548" chassis dyno results
Finally made it to the chassis dyno. I went to NE Dyno in Worcester, MA and made 3 pulls. All pulls were through the full exhaust system. Up to this time I had run exclusively 93 octane pump gas, but for added safety I topped off this morning's refill w/ 3 gal of 110 race gas.
Not knowing exactly where peak HP would end up, I installed a 7000 rpm chip in my MSD 6AL and pulled to the limiter. My previous setup peaked at 6300 rpm and my new cam has 12 degrees more intake duration. The first pull made 664 RWHP @ 6400 and 574 RWT @ 5200 running 36 deg timing and 84/84 jetting. A/F curve was flat, but just a bit on the lean side.
For the next run I increased the jetting to 86/86 and re-installed a 6600 rpm chip in the MSD. This run netted 665 RWHP and 603 RWT. A/F ended up close to 13:1. Clearly it liked more fuel.
For the last run I decided to pull some timing out. Everything I've heard and read on the new AFR BBC heads suggested they run best with modest timing compared to many other BBC heads. For comparison, my previous setup w/ ported Brodix-2 heads made peak power w/ 41 degrees total timing. With 34 degree timing and keeping the 86/86 jets it made 676 RWHP and 612 RWT.
Three runs and I was able to gain 12 RHWP and 38 lb-ft RWT. And Dean at NE Dyno gave me the group discount rate even though I ran solo. Thanks Dean!
I think its ready for the Vette-Viper shootout Oct 16 at NE Dragway!
Take care,
Mark
Not knowing exactly where peak HP would end up, I installed a 7000 rpm chip in my MSD 6AL and pulled to the limiter. My previous setup peaked at 6300 rpm and my new cam has 12 degrees more intake duration. The first pull made 664 RWHP @ 6400 and 574 RWT @ 5200 running 36 deg timing and 84/84 jetting. A/F curve was flat, but just a bit on the lean side.
For the next run I increased the jetting to 86/86 and re-installed a 6600 rpm chip in the MSD. This run netted 665 RWHP and 603 RWT. A/F ended up close to 13:1. Clearly it liked more fuel.
For the last run I decided to pull some timing out. Everything I've heard and read on the new AFR BBC heads suggested they run best with modest timing compared to many other BBC heads. For comparison, my previous setup w/ ported Brodix-2 heads made peak power w/ 41 degrees total timing. With 34 degree timing and keeping the 86/86 jets it made 676 RWHP and 612 RWT.
Three runs and I was able to gain 12 RHWP and 38 lb-ft RWT. And Dean at NE Dyno gave me the group discount rate even though I ran solo. Thanks Dean!
I think its ready for the Vette-Viper shootout Oct 16 at NE Dragway!
Take care,
Mark
Safety Car
Joined: Aug 2001
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From: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
Mark, great numbers. No doubt those AFR heads are killer. It would be cool if you could keep the secret of whats under that hood until you blow away a few of the Vipers. "Naw it's just a stock 427 with a cam." 
Race Director
Joined: Jan 2000
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From: Corsicana, Tx
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I think after all the different combinations....you've definitely hit a winner! And we *thought* it was good before!! WOW!!!
The amount of power it makes at that low of an RPM is definitely a testament to the AFR heads and your matched intake. That is simply airflow management at it's best!
It is interesting that even though the cam is significantly larger, the RPM at HP peak is not much different. I think TQ peak rpm is a little higher though right? That could be the effect of the larger cam.....I think to move rpm higher would require bigger intake or carb maybe? I bet a spacer would help yours like it did mine...to bad it won't fit under hood. Makes you wonder how far those heads would go with an even smaller cam? Not sure what you would do with any more mid range power as it is!
But either way, you're up over 100 RWHP by changing cam, heads, intake, bore size and ahair more compression. That is incredible when you were already making what you were. It's hard to find a measly 100 RWHP at that point!
I think you're going to have fun at the drags! Better practice your fancy footwork and how to walk that sucker out of the hole!
Congratulations!
JIM
The amount of power it makes at that low of an RPM is definitely a testament to the AFR heads and your matched intake. That is simply airflow management at it's best!
It is interesting that even though the cam is significantly larger, the RPM at HP peak is not much different. I think TQ peak rpm is a little higher though right? That could be the effect of the larger cam.....I think to move rpm higher would require bigger intake or carb maybe? I bet a spacer would help yours like it did mine...to bad it won't fit under hood. Makes you wonder how far those heads would go with an even smaller cam? Not sure what you would do with any more mid range power as it is!
But either way, you're up over 100 RWHP by changing cam, heads, intake, bore size and ahair more compression. That is incredible when you were already making what you were. It's hard to find a measly 100 RWHP at that point!
I think you're going to have fun at the drags! Better practice your fancy footwork and how to walk that sucker out of the hole!
Congratulations!
JIM
