Dyno Sheet - HP and Torque Question

[Archrms]

Native1,

Are the changes in HP & Torque cumulative with each change you made, or did you go back to your base setup to determine how each change affected your original numbers?

[native1]

The first pull I did (blue line) was after all of the engine modifications except the side pipes. The red line is a pull I made after changing side pipes and nothing else.

I dont know what each modification made in HP except for the air filter and side pipes.
But my guess is this:
Original HP from roush 427 srtw(crankshaft) was 510 hp and 528 tq
950 cfm Carb add 20 hp +-
Vic JR intake add 10 hp +-
Side pipes add 15-20 hp +-
Bigger airfiter add 10 hp +-

Present rwhp 460 +- TQ 440 +-

Pic only shows Gains of side pipes.

[native1]

This pic shows gains from airfilter only.
Made 8-9 Hp up in the big end.

[petegtsv10]

Originally Posted by Jimbocobra

native1,
No problem hijacking the post - even though I have DYNO ENVY, you indirectly may have answered something that I asked in another post. Is the only difference the side pipes between the red and blue on the second page of you dyno sheet only due to the change in pipes - without other modifications? I did notice they were not done on the same day. I have been trying to get accurate information on how much hp is lost with the BDR pipes. If you have 570 gross hp and you are picking up 15-20hp (I'll split the diff and say 18hp), then the stock Backdraft pipe lose about 3% to 3.5%. Does that sound right to you?
In my case, with 450hp, I'd net 13hp, seems like an expensive way to pick up power. Your thoughts?

Jim,
While my engine is at Clayton's, I've taken on the project of making sure my exhaust is NOT the weak-link when the mods are done. (AFR225 heads and solid roller cam) After many forum searches and many houre of long distance phone calls, here's what I'm doing:
2" custom equal-length (32") headers into a real 3.5" merge collector. That will taper into a 3" (22" long) ClassicChambered CobraPack muffler. It will look almost like the FFR pipe when it's done, but flow and scavenging will no longer be a question. And, as a bonus, I'll have my FFR sidepipes and headers to sell and I'll have a much deeper tone.