dyno day for the demon

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northeastmopar

northeastmopar

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Pulled at 350 horsepower and 360 ftlbs of torque at about 5500 RPM. I am told the engine HP should be about 20% higher or somewhere in the 425HP range. I thought it would be a little more, but I am thrilled the way she rolls along. Plenty of power and a nice ride with great idle for a driveable street car. Engine is a 340 stroked to 416.
 
northeastmopar said:
Pulled at 350 horsepower and 360 ftlbs of torque at about 5500 RPM. I am told the engine HP should be about 20% higher or somewhere in the 425HP range. I thought it would be a little more, but I am thrilled the way she rolls along. Plenty of power and a nice ride with great idle for a driveable street car. Engine is a 340 stroked to 416.
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I'm about to build a very similar engine. That's plenty of power to get anyone in trouble in the streets.
 
All dynos are variables in their own right. I use 18% for drivetrain loss with an auto, 15% for a stick. That's based on a dyno shop I ran for a short time. So that would put your numbers around 413. And I agree - a mild 4" stroker. It will be a fun ride.
 
moper said:
All dynos are variables in their own right. I use 18% for drivetrain loss with an auto, 15% for a stick. That's based on a dyno shop I ran for a short time. So that would put your numbers around 413. And I agree - a mild 4" stroker. It will be a fun ride.
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That's closer to what I used and it was very accurate compared to track numbers. It would have to be a very inefficient drive train to eat up more than 18 and 15%.
 
You probably have another thread going about the build but what parts do you have? Intake, heads, cam, carb?
 
stroked340 said:
Thats a very mild 416...
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Yes, the shop that put together my internal parts asked me if I was building a race car and I told them no. It also has edelbrock heads and dougs headers icon forged pistons, lunati 60404 advertised duration 279in 287ex. also has roller rockers. Holley 750. Edelbrock performer rpm intake. I actually thought it would be doing a little more. Sure does feel like it when I stomp on that pedal.
 
northeastmopar said:
Yes, the shop that put together my internal parts asked me if I was building a race car and I told them no. It also has edelbrock heads and dougs headers icon forged pistons, lunati 60404 advertised duration 279in 287ex. also has roller rockers. Holley 750. Edelbrock performer rpm intake. I actually thought it would be doing a little more. Sure does feel like it when I stomp on that pedal.
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The engine masters episode is a very relevant here. Built a very similiar engine with very similar results. Then they switched to a big single plane intake and did some serious work to the ports on the heads and intake and added 90 hp putting it over 500. You can get big numbers of the strokers but you will sacrifice low end torque big time.
 
Get that puppy out to the track and it may just outperform the guys running 475hp motors off the happy dynos.
 
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It's lower than I would expect but that could be from the dyno or anything else. Only the track will tell for sure. Weigh the car, and get an accurate MPH. Then figure out horsepower from those.
 
mopowers said:
Get that puppy out to the track and it may just outperform the guys running 475hp motors off the happy dynos.
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there is a lot of truth in this statement. lol seen a lot of 500 hp strokers running 12's.
 
The 455 Buick engines had 510 LB FT of torque stone stock and they lasted and lasted and lasted. Tire shredding torque and total reliability.

Sounds to me like you have close to the same thing. Enjoy it.
 
OK. I just realized this week that I had not checked the fluid level in the 727 before doing the dyno pull. So I checked it and I put in 2 more quarts of royal purple and it appears to still be down a quart. SO, I screwed up big time and I am lucky the tranny is running good after pulling 5800RPM on the dyno and being down 3 quarts of tranny fluid. I am now wondering if that lack of fluid played into the somewhat low dyno results. The dyno guy said he did not understand why with 3:55 gears, that I was doing about 4000 rpm at about 80MPH? He said that seemed way too high for a stroker motor. Now I am wondering if the missing 3 quarts of tranny fluid had caused that??? Been slowly bringing it up to full and it appears it was lacking 3 quarts? I may take it for another dyno pull?
 
I suspect the dyno is off somewhat.
Taking the numbers from post #1 your torque would only be like 425 ftlbs which is really low for a 416.
And that number at 5500 rpm is entirely off.

When it feels strong though, enjoy it!
 
doogievlg said:
The engine masters episode is a very relevant here. Built a very similiar engine with very similar results. Then they switched to a big single plane intake and did some serious work to the ports on the heads and intake and added 90 hp putting it over 500. You can get big numbers of the strokers but you will sacrifice low end torque big time.
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I'm on my second stroker, the first was a 408", ported Edelbrocks, 260/264 .628"/.633" flat solid, Victor 340, 10.9-1. The current one is a 434", ported Indy heads and intake, 263/271 .711"/.719" solid roller, 11.2-1. Both engines have tons of power down low.
 
@northeastmopar

Being down 3 (?) quarts of trans fluid is super significant! Build thread link?

@justinp61

The 434 is with what crank and block?
360 x 4.***
Build threads & Dyno sheets to the engines above by chance?
 
I'd think a lack of that much fluid would affect the numbers for certain. As for how much, I doubt it would be a monster change. Run the car at New England Dragway. Don't sweat any further dyno would be my advice.
 
Carb might be on the small side, on my 408 I have run a BG 825 mighty demon which tend to flow bigger than other carbs of same cfm and am currently running 800 cfm eddy thunder. Not that you need it for you intended purpose, but it could be what is hurting you number.
 
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