512 chassis dyno- what will it make?

My buddy has a mustang dyno. I am going to try and get a few pulls soon if he isn’t too busy. I had my 408 demon on it and the numbers seemed right- 350hp 400tq at the wheels. I never got that car to hook at the track but it mph’d 108-109 consistant so it doesn’t seem like an optimistic dyno.

Whatever numbers I get are just for fun- I am curious what it will say but my ego isn’t hinged on it or anything! I’m sure we’ll fiddle with the timing and WOT AFR for max power but it’s not like I’ll ever dead hook it on street tires.

Anyway- here’s the fun part: what will it make to the wheels?

Source 400/512,
unported stealths,
rpm intake,
sniper efi & hyperspark timing,
Small tube shorty headers, 3” downpipes, 3.5” flowmasters
10.25:1 CR,
.507/.510 240°/246° Comp hydraulic flat tappet
727,
3.21 gear 9.25 sure grip


I was building with a goal of 475-500hp & 500+ tq all done by 5500 so my guess is 380hp/425tq at the wheels.

Closest guess gets a free mopar tattoo at my shop if you’re into that sort of thing, or a shot and a beer if yer not 😉 I’m near philly.

Video of idle and rev with the holley 950 used for break in and not enough timing at idle. It’s even stronger and smoother now 👍
https://youtu.be/9BnnI9xXlh4

394 RWHP

421 RWHP

Since it is a new combo I don't think I'd pay too much attention to the numbers. Make sure you turn the data logger on for each pull and then pay close attention to the learn table to see what the system is doing. If the learn table is filling up with only small numbers then you're dialed in and the dyno numbers should be good, otherwise you need to make some changes. On the data logger you want to look at total fuel flow and injector duty cycle to see if your fuel system is up to par. You'll also want to look at the actual AFR and how it compares to your target AFR.

I'll be curious to hear your experience with the Sniper on a dual plane.

Thanks for the sniper tips Andy! Like I said I’m not worried about hitting a number. It’s a street build and my goal was to make it faster than people would expect and fun to drive. It should be able to hang with most new cars at a stoplight that cost less than a house- I got nothin for a hellcat or the top model vettes & stuff like that. I wouldn’t mind running a high 12 at the track around 110 115mph but I don’t care what it does and I’m not going to optimize it for that purpose.

But in a world where a 900-1200hp turbo LS is the default cheap big power hotrod I have no interest in playing the numbers game. Just naturally aspirated grunting big off idle torque is what I want! Plus a mopar and something different that I had the experience of making everything myself- sometimes even twice (oops...)

PJ68rt from what I’ve read online the sniper doesn’t have fuel distribution problems with the dual plane. I’m sure it would be better than TBI if I was to run 8 injectors but it already idles strong, has excellent throttle response, starts and warms up like a new car, and leaves a cloud of tire smoke behind me any time I jam the throttle. Can’t ask for much more on a fun street build.

But Andy- what’s your guess?! I can’t think of anybody more qualified to take a stab at it. Or was your post your way of warning me that I am going to see 280hp 450tq and not to be sad haha

On an engine dyno I'd expect to see 500 hp from that engine. A chassis dyno with a manual transmission would be 425 hp. No idea with an automatic since sometimes the torque converter really messes with the chassis dyno numbers.

At the wheels:
527 tq
362 hp

I’m more than happy with that! HP was still climbing at 5500 but we had a couple issues- the dyno sparkplug wire clip sensor wasn’t working so he did the pulls based on speed and the lines weren’t crossing like they should because the tires were growing. I’m sure there’s a little more Hp upstairs before it falls off a cliff but 5500 is already above normal operating range for how I use the truck.

We found a huge torque improvement down low when I copied and pasted a holley v4 spark map into the sniper table. I did the first pull using the simple timing values on purpose to see how much improvement we could find. Much flatter and higher curve now. We found a little bit of power messing with AFR but most of it was from the sniper learning WOT cells that are impossible to hit on the street after a couple pulls. It was a little rich at first.

The kid in me is disappointed in the max HP but it’s not surprising with the small unported stealths and mild cam. I always heard torque is king on the street and I have gobs of it everywhere!

Should be good for like a high 12 Around 110mph? Dunno if it will ever see the track or get set up to really hook. Gotta weigh it but 3200 is a good guess.

Looks like fun and you improved a bit. Good times.

Thanks!

Using ‘let’s make a deal’ rules nobody came closest without going over so nonwinners on the guess 😂

Need to see what the rpm scale is on the bottom of the sheet, and the HP scale on the right?

The upper most curve looks like it’s at about 440ft/lbs where it ends.
What rpm is that at?(or is the scale “speed”)

Here ya go. We pulled in 2nd so it wouldn’t kick down. The first pull we went to 5000 to see if it was even still making power and the last pull is longer we went to my limiter at 5500. I wanted to see numbers- sure- but I was really there to see if we could find any power and smooth out the tune in my actual operating range. I’m sure I could have posted a little more HP if we kept revving it but there’s no real world benefit for me beating on my parts upstairs when I mostly shift at 4500 on the street and break traction at will.

Maybe I’ll get bored of it after a while and throw some trickflows and bigger headers & cam at it but it’s already faster than my old 408 demon and my current daily 6.1 challenger.

Can you clarify.....was the dyno pull done with the trans in 2nd gear? Are the numbers on the dyno sheet corrected for the extra torque multiplication due to not being in a 1:1 gear? I didn't think TFs will downshift in 2nd much above 2700-2800 RPM in high gear due to the governor.