Dyno Sheet - HP and Torque Question

Jimbocobra · #1 (**permalink**) 11-27-2009, 09:52 AM

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 Carburation

http://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 · #2 (**permalink**) 11-27-2009, 09:59 AM

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.

vector1 · #3 (**permalink**) 11-27-2009, 11:59 AM

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 · #4 (**permalink**) 11-28-2009, 08:30 AM

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 · #5 (**permalink**) 11-28-2009, 09:00 AM

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

native1 · #6 (**permalink**) 11-28-2009, 08:24 PM

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 · #7 (**permalink**) 11-29-2009, 11:54 AM

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 · #8 (**permalink**) 11-29-2009, 12:34 PM

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

patrickt · #9 (**permalink**) 11-29-2009, 01:53 PM

Quote:

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 · #10 (**permalink**) 11-29-2009, 04:40 PM

Did you get the AFR heads and cam done yet?

petegtsv10 · #11 (**permalink**) 11-30-2009, 07:57 AM

Quote:

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.

native1 · #12 (**permalink**) 11-30-2009, 09:03 AM

Quote:

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 · #13 (**permalink**) 11-30-2009, 10:58 AM

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

Jimbocobra · #14 (**permalink**) 11-30-2009, 01:46 PM

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?

native1 · #15 (**permalink**) 11-30-2009, 04:57 PM

Quote:

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?

Yes, that is correct. The second dyno sheet is the difference between the stock BDR pipes and the new ones. No other modifications were done in between the 2 dyno pulls. I was trying to find out for myself...

The side pipes are not totally custom. I simply ordered new glass packs from Stainless Specialities and had them welded in place of the restrictive BDR glass packs. I am sure you have looked inside your pipes and noticed that the exhaust is routed between 2 small pipes inside the glass packs. The new glass packs are straight through. The project cost me around 800 bucks in the end. I could notice the improvement through the seat of my pants. It also sounds so much better. It sounds a lot deeper but not a lot louder.

Just another note. I tried a different air filter "bigger" with the pleats on the top of the filter. I did it in between pulls for an experiment... Picked up 9hp at the wheels. I don't run that filter because I don't like the way it looks but I thought that was a lot for only an air filter.... "first dyno sheet"

Also I have read that Mustang dyno's are not as optimistic as the Dyno Jet dyno's... So don't feal too bad.

Jimbocobra · #16 (**permalink**) 12-01-2009, 01:09 PM

That is great information on the stock Backdraft sidepipes, thanks for posting it. I was looking at Roush's site and it looked like your engine is rated at 515hp, but if your putting out 470+hp at the rear wheels, so you must be close to 560hp. Do you know what the rated hp is on your engine?
Funny you mention the air cleaner top, I just picked one to put on when I go drag racing this spring. My aircleaner has a polished aluminum top, but sits below the hood scoop, so the air passes over rather than straight into the aircleaner, I think it will help get a bit more power. Right now, the AFR heads and cam + labor I am going to add will set me back $3,000. I should pick up about 75 hp, putting me in the 525hp to 535hp range. I'll post the new dynosheet then, maybe I can close the gap a bit (for a lot less than a new Roush).

vipertocobra · #17 (**permalink**) 12-01-2009, 01:17 PM

His increase in power is from the 950 carb, Intake and pipes....Thats where im headed next !!

fastd · #18 (**permalink**) 12-01-2009, 04:44 PM

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 · #19 (**permalink**) 12-01-2009, 06:56 PM

[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 · #20 (**permalink**) 12-01-2009, 07:12 PM

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.