Magnum VS Hemi

DionR said
??? Not following.

I'm certain the 380hp crate motor has a larger cam then either the 5.7 or 6.4. Pretty sure the stock 5.9 (and 300 hp crate motor) has a smaller cam than the 5.7 truck motor, though. Never meant to imply the 5.9 cam was bigger than the 5.7 cam. Only saying it took a big cam in the Magnum to catch the stock Hemi.

But your question confuses me. Sorry.

Pretty sure the G3 rocker ratio is 1.65:1

Right. SRT8 looks a touch smaller than the 380HP. More lift, possibly same int dur, less exh dur. Wouldn't be suprising if 380HP was flat tappet, which isn't great for HP especially not for HP for the cam size- lift's exceedingly low for duration, may well've been intentional due to spring selection.

I guess where much of my point lies is the 318 Mags have a bigger cam and shorter stroke than the 360 Mags- but they're not less drivable. It's just not a tangible difference. With MPFI there's not a lines you'll cross, which is why following the MAF 5.0 Mustangs it became so common to see FAST street cars daily driven. It's not that the newer motors are so much tamer that has appeal, it's that the 6500RPM 400cfm motor you can drive in the road- and about anybody could right behind you. In the new Hemis, they come with the headflow- the Mags don't have it out of the box. It probably won't cost the difference between the two to get where it needs to, but to truly match the Hemis headflow for a N/A motor that's gonna be over 520-530hp it'd likely take more than the difference.

DionR said
Couple of years ago I put together a spreadsheet adding up the costs of a hemi swap versus a rebuild of my numbers matching 360. In the end, a rebuild of my 360 with better compression, a set of Edelbrock heads, a roller cam and Megasquirt EFI (w/ a fuel system) was looking to cost me $6,600. If I bought a truck 5.7, plus all the parts to swap it in (including the EFI fuel system), with cast iron manifolds, a Hot Wire Auto harness and ECU, car timing cover, water pump and intake, plus whatever miscellaneous stuff I could remember, it came to $5300. The difference was big enough that I could have done TTI headers and a new cam, and still been cheaper than rebuilding the 360 and adding EFI.

I also looked at just swapping a roller cam, Edelbrock heads and EFI onto my current shorblock, and that total came to $5600. Even just a better carb with the roller cam and Edelbrock heads was $2950. That was just if I wanted to try and keep up performance wise.

Best I could get the Hemi down to was $4050 with an OE harness I modified and a B&G flash to the ECU, and the rest of it being truck parts. That was about the same as rebuilding the 360, adding Edelbrock heads and a roller cam, but no EFI.

I would say that if you have to rebuild a Magnum (or want to build a 408), the G3 starts looking more cost effective, if you can find one that isnt broke.

If either one is going to need a rebuild, the Magnum might be more cost effective.

Those numbers don't directly correlate with a 5.9 rebuild, though, as that included some costly lifters for the roller cam. But even if I saved $500 by using a Magnum block, and bought EQ heads instead of Edelbrocks, I'm not sure it would pencil out.

Hear that. Around half in the 408, $600 in conversion to Mag FI. Next time would just buy a 'rango, 'kota, or grand 4x4 for a donor- foolish not to. Roller off the bat, full fuel system there, motor, and could even have a shot of netting out better.

5.7s are still expensive here. Running Magnum vehicles, even with reasonable miles can be had cheap. $400-650 for a running, driving Mag truck donor and then the $1000-1800 into the motor to improve it is still better than buying conversion parts for an $1500 motor.