438ci Hemi Dyno. Devil is in the details.

It's been about a year and half since I first ran this on the dyno.

I've had a bit of time for revisions since someone rear ended me at 40mph on the way home. Car is all fixed and completely repainted now, better than ever.

Basic combo is-

.060 over 426 so about 438ci.

MP iron block, CP pistons, 12.4-1 .043 rings. GZ vacuum pump

MP iron heads (I ported them)

Cam motion low lash solid roller 262/262 112lsa, .658 .612 measured at the valve. Morel black mamba lifters. Trend tapered pushrods. PSI 1.4" OD valvesprings with TI locks and retainers.

Holley HP efi. Edelbrock dual 4 intake, ported. 80lb deka injectors, Flex fuel

TTi 2.125 headers into dual 3" exhaust, pypes race pro mufflers out to stock style tips.



So here were the revisions between the overlayed graphs.

Added HVH 1/2" spacers under the throttle bodies

Changed stock diameter lower pulley to ASP underdrive (it was blowing belts into low earth orbit) Way too much pulley ratio for the rpm.

Switched from 20w-50 Brad Penn to 5w-30 Royal Purple XPR. Also changed to synthetic trans and diff fluid.

Rebuilt tailpipes (they got smashed) with the largest radius bends I could fit.

Last thing that I'm sure made a difference to the results was removing 15x10 steel wheels and replaced with W23-ish 15x10 aluminum wheels.

Made quite a difference! Feels awesome on the street.

VERY cool !!!!!!!

And I love the car, too.

Yes….that is gorgeous!!!

Did you find the true peak HP RPM?
It sounded like itw as till pulling well when he back out of the throttle?
I try to find peak HP RPM and take it form 300 to 500 RPM above that to make sure the motor hasn't nosed over and then got a second breath, which I have seen more than once

Thanks guys

Cab, it seems it peaked at 7250. It doesn't nose over hard after that but the rev limiter is set to 7650 due to driveshaft critical speed. (so pulled to limiter was about 400rpm past peak)

I could put a carbon driveshaft in it and test higher but doubt it would do anything but continue to gradually fall off. And..I think may be hard on the valvesprings and valvetrain overall if I push it to/through instability with a 2.25 steel valve.

Fwiw, the changes made were of course small but seemed to add up. When I ran it in initially and it threw belts I noticed a jump in power. Seeing that and the numbers now, I think a big part of the difference was the underdrive pulley.

Additionally

While I tried my best during the first dyno session, I was fighting belt issues/tossing belts.


Today, with the underdrive pulley and having no belt issues I was able to experiment a bit with timing.

The best numbers were achieved with 29deg total timing.

It would take 33deg (and more) no problem but would drop 10+rwhp in the process.


Fwiw, max power achieved at 29deg total was within 2hp at 35% alcohol and 70% alcohol.


Maybe I went to far. Basically what I'm trying to say, or what my observations are is-


-Total timing ended up lower than I expected.

-The above observation didn't change with additional alcohol. Still made the most power at 29deg regardless of alcohol content.

-Lastly, to the points above, yes I verified timing from idle to high rpm. (What is commanded is actual)

Very good returns for the changes made. Congratulations,and keep it between the ditches.👍

Nice A$$ car was this video made before or after the accident.?

She's a beauty.

Beautiful car, should be a hoot to drive too.

Seems like a lot of power for that combo. You did good.

Well done Sir, enjoy!

I couldn't keep a belt on my hemi. It would toss the belt the minute I hit the gas until I changed to a Dayco Top Cog belt and now I haven't thrown one even up to 7,500 rpm in over ten years. No other changes.


Mike

Thanks guys! Will try to keep it between ditches Dyno video and this one were made yesterday so after the accident.

there is no better sensation (maybe there are, in the bedroom ) than having enough power to break the rear tires loose at speed
The trick is knowing when and how to drive it correctly, so you don't hurt the motor, car and yourself Be safe, have fun


Do you have your shift lights hooked up to the two hood turn signal lights?

very impressive indeed !
i wished my charger was 1/2 as nice as yours !

Thanks guys! It was pretty cold yesterday but I think when it warms up a bit the Avon CR6ZZ's will hook fairly decent. (road race tire with 80 treadwear rating)

Cab, yes I wired in a relay so the hood lights function with the turn signals and also as a shift light from a Holley EFI output

Nice car. Good power. I like the shift lights.
Doug

I had a 484 hemi years ago....The little monster made 500hp & 500 torque to the tires with a little .630 roller cam. It was a lot of fun on tires.

My Hemi build made max power at 28 degrees total advance. I've been a B/RB Wedge guy for the last 40+ years and used to seeing 34 or 35 degrees. 28* seemed like not enough but the Dyno guy said 28 for my build was consistent with other similar Hemi builds. That hemispherical combustion chamber is pretty efficient. Also, it's 604" and like 11-1 on the CR (all aluminum) but runs on high-octane pump gas. I think the cam bleeds off some pressure and the aluminum soaks out lots of heat. It was one of last builds that came out of Muscle Motors.

^ Appreciate the info, good to know! You're the only other person I recall stating their hemi made the most power at sub 30deg timing.

Good heads and small cubes often will need less total timing.

That's some good Rwhp, sounds good too.
When I was dynoing my mazda to 10,500 rpm, some people told me the driveshaft was going to explode, but it never did, I was more worried about the clutch coming apart.

i'm impressed. big power for the cubes; especially at the tire. i like the way the dyno operator started at a low enough rpm to give you a good picture of the power curve. also impressed at how the car hung onto power and gained in the upper rpm range. what size are those carbs?

I really appreciate your attention to detail. It's top notch in every respect, your Charger is outstanding!

I love the turn signals used as a shift light.

Thanks guys! The throttle bodies are Holley 112-588, 1000cfm.


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What a nice build. Do you have pictures posted of the build/restoration?

Very nice Hot Rod! Well done! Thanks for sharing.

the turn signal shift lights are a great idea.
do they have a second bulb in them to still be used as turn signals ?

What company makes those W23ish wheels ?

Thanks guys.

Just one bulb on the turn signal lights. I wired in a relay so they work with both the turn signals and as a shift light. (voltage can either pass through to individual turn signal light as normal or be illiminated together by the ecu)

The wheels were made by Curtis Speed in California (not production, I had them made). Tires are Avon CR6ZZ road race tires. 80 treadwear rating. Diamondback put redlines on them.

Very nice! Surprised at the timing...mine likes 34°, but it's 575 inches.

Mine made most power and torque at 33 degrees at 528".

My 572 Hemi made max power on the dyno at 29* but runs quickest on the track at 32* and stays cooler on the street.

I love the Fratzog detail on the wheels. Since that is part of the new EV branding for Stellantis, instead of people asking if that thing got a Hemi, they'll be asking if it is electric!!

Thank you. I originally thought I would fill in the fratzog on the cap with black paint but not sure. (same with my indecision about a tail stripe)

I don't know, I think that's really subtle without black paint. The way it looks now, if I walked past it at a car show and saw that detail, I would just chuckle and smile. I'd probably want to meet you and shake your hand . The rest of the car is like a big hammer, the subtlety of the Fratzog detail helps with the balance. Are those Coyote pencil coils? If so, I bought a set of those from MSD and hope to install sooner or later. Besides shortening the boot that goes over the spark plug, did you have to make any other mods to the coil? The MSD coils have that stainless steel coil spring inside the boot for connectivity between the coil and the spark plug tip. That looks a little sketchy to me but it works for the OEM. And, you have to add a stud or some sort of attachment provision to the valve cover. And once you do that, you're locked into a specific direction on the coil wiring. I thought it might be neat to run all the coil trigger wires to the rear of the engine to make the casual observer wonder if it is a Gen I 392. What ECU are you using? Thanks - nice car!

Thank you once again

Yes they are Coyote coils.

I trimmed .125 off the end of the rubber boot with a razor blade. (inside is a spring as well that had enough range)

Shortened the ridge on the plug tubes by .200 on a belt grinder.

Used a bolt and .400 thick threaded spacers for mounting.

I'm using a Holley HP ecu.