360 block limits

-
Z

Zach1234

New Member
Joined
Mar 2, 2018
Messages
3
Reaction score
2
Location
56308
Current motor is a 1978 360 bored .030 over, eq magnum heads slightly ported, edelbrock rpm airgap slightly ported, 10.7:1 compression .
Scat cast crank and rods and srp forged pistons. Arp rod and head bolts, possibly main cap bolts too. Internally balanced.
Cam: 109 lsa
Duration @.050 239 242
Lift .562 .559
Currently makes 440 hp 490ftlbs

With proper ring gap, fuel and ignition how big of a shot would a motor like this handle? Thinking of a 100 shot. Would something like this require the water jackets to be half filled?

Also thinking of getting a 90s magnum 318 engine and putting a cam in and slight head work and hope for 375-400hp. Then mess with nitrous on that motor. Just so I don't scatter my expensive motor. Would the cast pistons in those handle significantly less?
 
While I believe you would be ok with the 100, I would build a nitrous motor for nitrous.
 
The real limit of what you have isn’t going to be as much the block as it is how much you can control detonation.
9 times out of 10 when a nitrous engine fails, detonation is the culprit. And there’s more to it than just the tune, too such as chamber shape and finish, head gasket selection and using studs to keep the heads and block held tightly together. I think 100hp is doable with a limit of 200, but only if the ring gap is set and you’ve got head studs with premium gaskets that prevent sharp edges at the top of the bore. I’m more in favor of the magnum (or a dedicated nitrous built engine, as CH1ll suggested) for use during the learning curve.
 
I'd put a 300 plate shot on it so quick it'd make your head spin. But you're gonna need race gas.
 
pittsburghracer said:
360 blocks are weak truck motors
Click to expand...
For what you’re doing, I would respectfully agree with that statement! I wouldn’t want it to make it live on a 100 shot at every opportunity available, but it will be fine for the occasional hit.
 
Zach1234 said:
Current motor is a 1978 360 bored .030 over, eq magnum heads slightly ported, edelbrock rpm airgap slightly ported, 10.7:1 compression .
Scat cast crank and rods and srp forged pistons. Arp rod and head bolts, possibly main cap bolts too. Internally balanced.
Cam: 109 lsa
Duration @.050 239 242
Lift .562 .559
Currently makes 440 hp 490ftlbs

With proper ring gap, fuel and ignition how big of a shot would a motor like this handle? Thinking of a 100 shot. Would something like this require the water jackets to be half filled?

Also thinking of getting a 90s magnum 318 engine and putting a cam in and slight head work and hope for 375-400hp. Then mess with nitrous on that motor. Just so I don't scatter my expensive motor. Would the cast pistons in those handle significantly less?
Click to expand...
I don't think you have any problems till you're around/above 550+ horsepower.
I lost the number five cylinder wall @410cid solid roller ,186cc heads, 9.98-1 comp @ 7,ooo rpm in 2nd gear.
I attribute that to a piston coming apart at first then lumberjacking the cylinder wall with the H beams I run.
 
Magnum blocks are better and come with factory roller lifters and the lifter bosses are better. Better block.
Just an FYI all 318,360,383,413 were originally made for trucks, the cars received the benefit of the durability built into these platform engines.
340 and 426 Hemi were always only made for hi-performance applications, not trucks.
 
There were 318 truck blocks and there were 318 passenger car blocks that's what I know and you can see it on the front of the engine in the stamping. Hence there were also 318s that had four motor mount ears 'T' and the others had three 'Passenger cars'
400s were all kinds of things...LA360 predominantly vans..but they did make ththe 75 dart sports....all through the 70's mostly Van's though. LA roller 360s I have only found in vans come to think of it...
 
150 shot easy
Call piston manufacturer to find ideal ring gap
MSD 8680, dash controller timing, 2 degrees per 50 hp, total retard 6 degrees on the gas
 
There's a group on Facebook called "RWD BOOSTED MOPAR MUSCLE" where quite a few people share details about their high hp small blocks.

Many over there are pushing their stock block beyond what is conventionally considered "safe" or "reliable".

On the other hand there is also a lot of anecdotal info on forums of people who have had/seen blocks fail at around 600hp too.

To me this indicates that there is no definitive answer as to what works and what doesn't, or how reliable you can expect X combination to live at Y horsepower.

But IMO if you push your OEM 360 block past 600hp you should anticipate that at any moment it could potentially suffer an instantaneous unscheduled disassembly.
 
^^^THIS RIGHT HERE^^^ Because of how much is left in the block to start with before it starts to crack under high load. Add into it that the larger the number of hp gain, the more probable that you’ll have detonation happen that won’t audible until the engine is already in pre ignition.
 
This is a good beer...

IMG_20221202_195533.jpg
 
I don't know if there's a golden number, but I plan on spraying the piss out of my 421 this season. To the MOON, baby!

I have my own torque plates, which I think is a huge benefit when it comes to quality machining. Good hardware. Light rotating assemby. Correct ring gap and plugs range. And I have Ross add extra material around on the crown of my pistons. I also build my nitrous motors loose.

When it comes to carbureted nitrous motors, detonation is the killer. Because ultimately, it's impossible for a carb to distribute fuel equally to each cylinder. So eventually, the carb/intake is going to pick on a cylinder, and if you're not careful you'll window your block. On the big SHOT nitrous motors (300+), I much prefer EFI because each cylinder has its own dedicated fuel source and it's more controllable.

But if you have a quality motor with good parts, quality machining, adequate fueling, and you follow the golden rules, it should live for a while. If you f-up, it'll bite you. That's the game
 
Just Send It said:
I don't know if there's a golden number, but I plan on spraying the piss out of my 421 this season. To the MOON, baby!

I have my own torque plates, which I think is a huge benefit when it comes to quality machining. Good hardware. Light rotating assemby. Correct ring gap and plugs range. And I have Ross add extra material around on the crown of my pistons. I also build my nitrous motors loose.

When it comes to carbureted nitrous motors, detonation is the killer. Because ultimately, it's impossible for a carb to distribute fuel equally to each cylinder. So eventually, the carb/intake is going to pick on a cylinder, and if you're not careful you'll window your block. On the big SHOT nitrous motors (300+), I much prefer EFI because each cylinder has its own dedicated fuel source and it's more controllable.

But if you have a quality motor with good parts, quality machining, adequate fueling, and you follow the golden rules, it should live for a while. If you f-up, it'll bite you. That's the game
Click to expand...


You should go watch the 2023 Engine Performance Expo and pay attention to the round table discussions.

Here is the upshot. A carb gives the engine what it WANTS. EFI gives it what the tuner TELLS it.

There is a HUGE difference there and it’s worth understanding.

Fuel distribution issues are seldom a carb issue.
 
Rat Bastid said:
You should go watch the 2023 Engine Performance Expo and pay attention to the round table discussions.

Here is the upshot. A carb gives the engine what it WANTS. EFI gives it what the tuner TELLS it.

There is a HUGE difference there and it’s worth understanding.

Fuel distribution issues are seldom a carb issue.
Click to expand...

You're not one of those "carburettors are superior to EFI" people are you?
 
Rat Bastid said:
You should go watch the 2023 Engine Performance Expo and pay attention to the round table discussions.

Here is the upshot. A carb gives the engine what it WANTS. EFI gives it what the tuner TELLS it.

There is a HUGE difference there and it’s worth understanding.

Fuel distribution issues are seldom a carb issue.
Click to expand...
Cool. You do you. I prefer the control of EFI. Especially in nitrous and forced induction motors. More than 1 way to skin a cat
 
You must log in or register to reply here.
-

Back
Top