Dyno Sheet - HP and Torque Question

[Jimbocobra]

Here is a dyno Komet Motorsports in St. Charles, I just completed the dyno run last week. Frank was able to get the HP up dramatically, but I just noticed the torque was a bit lower than expected. The engine is supposed to be making 430hp and 450tq.
If I lose 20% to drivetrain inefficiencies, the hp the engine is making is really about 465hp (up from the factory rating of 430hp and consistent with what many magazine articles have said about the Ford Motorsports crate 392. See article Cornucpoia of Carburationhttp://www.airflowresearch.com/artic...024/A24-P1.htm).

Torque is about 355 at the rear wheels, which is also a 20% loss from the manufacturers number of 450 (450-20%=360). I ran it through factory sidepipes, but I still though it might be more. The magazine article does show the factory torque number is accurate at 450 vs. 455 in the article. Then the torque number on my dyno sheet seems close if 20% loss in torque is typical, so the question:

Is torque supposed to lose 20% due to drivetrain inefficiencies as well?

[Tommy]

Horsepower is calculated from the torque produced at a given RPM. If one is down by 20%, the other must be down by the same amount.

[patrickt]

Originally Posted by Tommy

Horsepower is calculated from the torque produced at a given RPM. If one is down by 20%, the other must be down by the same amount.

Tommy's right. I had to actually do the math because it didn't seem like it was, but it is.

[Jimbocobra]

Did you get the AFR heads and cam done yet?

[petegtsv10]

Originally Posted by Jimbocobra

Did you get the AFR heads and cam done yet?

The Claytons have my engine and as soon as my current piston specs are verified we'll order the heads, etc. For my part, I'm looking into exhaust mods to complement the new heads/cam work.

[vector1]

that looks like a pretty good torque curve, steady i mean. where is the rest of the sheet, what does the tq. curve look like at the higher rpm or where does it drop off?

unless you put two engines on the same dyno, or you know everything is set up exactly the same with same atmospheric conditions then comparisons are pretty general imo.

[native1]

Here are some pics of my Roush/Backdraft dyno sheet. Best RWHP was 467. It is a Roush 427 srtw with Vic jr intake, 950 cfm carb, and custom side pipes.

[Jimbocobra]

Wow, those Roush guys make some nice engines - terrrific power! What pipes did you use?

[native1]

Pipes are from Stainless Specialities... They sound great and make a little more power. Yes, I am very pleased with my Roush/Backdraft combo. Thanks.

[petegtsv10]

Nice-looking pipes. Do you know the size of the primaries before they combine? (FFRs are 1 3/4") I'm planning to re-do my FFR sides with 2" into a merge collector. Some of the other SS pipes are only 1 5/8" in.

[madmaxx]

Native 1.

Why did you switch from the original manifold and carb? How much HP do you think it gained you. Oh and by the way your car is so UGLY!! LOL

[native1]

Originally Posted by madmaxx

Native 1.

Why did you switch from the original manifold and carb? How much HP do you think it gained you. Oh and by the way your car is so UGLY!! LOL

Sorry jimbocobra for highjacking your post... And thank you madmax for the kind remarks. I switched the carb and intake for more power. Some may disagree with the set up, but I think the dyno sheet speaks for itself. I also don't like the carbs Roush uses from the factory. IE vac secondaries. Giving up a little down low to gain a little up top was more desirable for me. The power seems come in a lot smoother now. It doesn't break loose quite as easy when I stomp on it. Actually makes the car more drivable. However I can still spin my Nitto drag radials through second gear.

If you look at the second dyno sheet pic you can see the difference between the stock BDR pipes and the new Stainless Specialities pipes. Its about 15-20+ in TQ and HP across the powerband. The red line represents the new pipes....

[vipertocobra]

we have almost identical cars...I love my 427sr/tw.... How do you like the nittos??

[fastd]

Native1,
Can you go into a little more detail regarding the pleats on the top air filter? Did you say you picked up 9 hp just by adding the pleated top?

I wish more people would provide the kind of data that you are providing; i.e. one specific change resulted in X hp and Y torque on the dyno. I am actually changing my exhaust and moving from a Holley 750 cfm with vacuum secondaries to a 600 cfm double pumper. I will post my dyno results in a day or two on a different thread (look for a thread titled "A little more horsepower").

[native1]

[quote=fastd;1005804]Native1,
Can you go into a little more detail regarding the pleats on the top air filter? Did you say you picked up 9 hp just by adding the pleated top?

The first dyno sheet pic was back to back pulls. Just a swap in air filter. You will notice this filter made a little HP (9) at the very top end. I still dont like the way it looks compared to the roush filter though.

The dyno tag on my 427 srtw said 510 hp and 528 tq from roush. After all the modifications the RWHP is a consistent 460+ and RWTQ is 440+. Pulls like freight train all the way to 6500 rpm.

I believe that the carb and side pipes were the biggest improvement in overall HP gains. Many carb "experts" have told me that fords like alot of carb cfm compared to the chevys. I am very happy with the 950 cfm carb...
I see 351's with 950 cfm carbs a the drag srip all the time. So a 427 has no problem swallowing all that air.

BTW. The car is very "streatable"... Here is the air filter.

[fastd]

Interesting. I actually installed the pleated top too and I think it feels a little better.

However, my dyno guy said that he doesn't like the pleated top and thought it would be better to try to get a more traditional setup but try to increase size of element to 4" (mine is currently 2+".

By the way, I have also recently been adding about 10-20% of 111 octane race fuel; it feels like a 10-15 hp boost; and it runs so much better.

[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.