360 Engine Build Guidance (Boost Maybe?)

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MonkeyTrev

MonkeyTrev

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I have a 65 Barracuda that has a mildly built up 360 installed in it. I am wanting to start a new engine build that will allow me to just swap the old 360 for the new 360. I want to build the new motors bottom end to be something I can build onto over the years (ALL FORGED). I have some plans of either doing turbo or torqstorm supercharger in the future. I have no experience building boost motors.

Is it possible to build the motor to run naturally aspirated for now, but have the rings gapped for future boost ?

Does stroking a motor affect its ability to accept boost? I am still looking at either buying a stroker kit or buying the pieces separate to get exactly what I want.

What is the ideal compression ratio to shoot for when running boost 8.5:1, 9.5:1, 10.5:1 ?

Here are a few of the parts I have put together so far (I am open for suggestions):
Crank - Eagle Specialty Products 436040006123 Eagle Forged 4340 Steel Crankshafts | Summit Racing
Rods - Small Block Mopar Connecting Rods | 273 318 340 360 5.2 5.9
Pistons - ?

Stroker Kit - DODGE Eagle Specialty Products 20102030 Eagle Competition Rotating Assemblies | Summit Racing
DODGE SCAT Engine Components 1-48033 Scat Engine Rotating Assemblies | Summit Racing
 
I have no experience with boost, but my concern would be that the LA small block really needed a 5th head bolt in the valley. If it were me I would look for one of the R’s with the 5th bolt. Not a simple or cheap thing. That also limits your head choices, but you get a much more solid foundation. They are heavy, 50-60 lbs heavier than a stock block. It really depends on how much you’re looking to make and boost level. I know in my class, when they build a long stroke 4”+ stock block small block. Most will do a short fill of hard block. Really helps ring seal and these are N/A motors.
 
What is your target HP goal? How is the motor intended to be used, as in 100% drag race, all street, occasional drag and mostly street, etc.
 
dano said:
What is your target HP goal? How is the motor intended to be used, as in 100% drag race, all street, occasional drag and mostly street, etc.
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It is a street car that occasionally sees the strip. I would be really happy with anything over 500hp.
 
furrystump said:
I have no experience with boost, but my concern would be that the LA small block really needed a 5th head bolt in the valley. If it were me I would look for one of the R’s with the 5th bolt. Not a simple or cheap thing. That also limits your head choices, but you get a much more solid foundation. They are heavy, 50-60 lbs heavier than a stock block. It really depends on how much you’re looking to make and boost level. I know in my class, when they build a long stroke 4”+ stock block small block. Most will do a short fill of hard block. Really helps ring seal and these are N/A motors.
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Additional head bolts or aftermarket block are not needed…assuming you plan to stay under ~900hp(turbo). Cometic head gaskets will hold fine, and 1008’s will hold at lower power levels. Some believe magnum blocks are tougher, and they are definitely heavier. Stock magnum cranks tested good to 850hp…turbocharged; superchargers are not as friendly. Compression depends on fuel, turbo/supercharger, tuning preference, vehicle use…opinion…lots of different opinions on that. Strokers are harder on the main caps/web, but I don’t know to what extent.

500hp should be cake. Check the forced induction section on this forum.
 
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turbovan said:
Additional head bolts and aftermarket block is not needed…assuming you plan to stay under ~900hp. Cometic head gaskets will hold fine, and 1008’s will hold at lower power levels. Some believe magnum blocks are tougher, and they are definitely heavier. Stock magnum cranks tested good to 850hp…turbocharged; superchargers are not as friendly. Compression depends on fuel, turbo/supercharger, tuning preference, vehicle use…opinion…lots of different opinions on that. Strokers are harder on the main caps/web, but I don’t know to what extent.

500hp should be cake. Check the forced induction section on this forum.
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I appreciate the info. I will check out the forced induction section.
 
350 hp 360, add a 200 shot for about $600,
Equals 550 hp , nitrous is the best bang (no pun intended) for the buck !!
 
A 350hp, hi-compression 360 is a real blast. This is an easy/cheap/reliable build. Get's into the 12s real easy, on street tires with street gears. With overdrive she can get fabulous hi-way fuel mileage, and she's a go anywhere/anytime girl. In the early-A, she might do low 12s. That's a heckuva car.
As a streeter, I fail to see the allure of boost.
 
It all depends on how much boost you add. You can still make OK power at 8 to 1 and add boost later. Extra ring gap won't hurt. Personally if I was boosting an engine, I'd not want more than 8 maybe 8.5, so you're not limited to only 5 or 6 lbs of boost. This is a really basic approach. Things like quench, cylinder head material, camshaft, intercooler, ignition retarding under pressure, all play a part in how much boost you can add.
Get the book Supercharged by Corky Bell. Good information. Also watch some of Richard Holdeners you tube stuff.
 
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Where to start? Ill go the simple route first. Put a turbo on the engine you have now. Get the fuel system up to task, and the turbo “kit” sorted out and I’ll bet it will meet your goals. A mild 360 with boost will sneeze 500 hp. That will give you the ability to learn all the intricacies of making it live on boost and do it on an engine you plan to replace anyway. Call it a sacrificial lamb but a tool that is invaluable. You’ll likely blow it up the first time around learning to tune it. Ask me how I know. But the knowledge will be well worth it. All the while building your forged bottom end stroker for boost and not trying to run it NA for a time which imo is a wasted effort. The book posted above by @Babyblue66 “supercharged” by Corky Bell is an EXCELLENT resource for any kind of boosted application, not just supercharging, and is great advice.
 
MonkeyTrev said:
Is it possible to build the motor to run naturally aspirated for now, but have the rings gapped for future boost ?

Does stroking a motor affect its ability to accept boost? I am still looking at either buying a stroker kit or buying the pieces separate to get exactly what I want.

What is the ideal compression ratio to shoot for when running boost 8.5:1, 9.5:1, 10.5:1 ?
Click to expand...

I’ll answer these separately;

1. Absolutely, gapping the rings for boost just adds a few extra thou of gap for heat. The engine will not run any different or have any more measurable blowby at 030 gap than 022.

2. Anything you do to make more power NA will make more power with boost. This includes adding stroke. Look up and watch a bunch of Richard Holdeners videos on you tube.

3. Depends on what fuel you are willing to run. 91 octane, e85, or methanol will all require vastly different compression ratios and different tunes. The first thing you should do before turning a wrench is pick your fuel, and that will dictate your compression ratio. There is no “optimal” compression ratio.
 
TT5.9mag said:
Where to start? Ill go the simple route first. Put a turbo on the engine you have now. Get the fuel system up to task, and the turbo “kit” sorted out and I’ll bet it will meet your goals. A mild 360 with boost will sneeze 500 hp. That will give you the ability to learn all the intricacies of making it live on boost and do it on an engine you plan to replace anyway. Call it a sacrificial lamb but a tool that is invaluable. You’ll likely blow it up the first time around learning to tune it. Ask me how I know. But the knowledge will be well worth it. All the while building your forged bottom end stroker for boost and not trying to run it NA for a time which imo is a wasted effort. The book posted above by @Babyblue66 “supercharged” by Corky Bell is an EXCELLENT resource for any kind of boosted application, not just supercharging, and is great advice.
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I second the recommendation to boost the existing motor. Just about everyone here(myself included) blew their first motor navigating the intricacies of boost. Might as well get it all sorted on a cheap build!
 
TT5.9mag said:
I’ll answer these separately;

1. Absolutely, gapping the rings for boost just adds a few extra thou of gap for heat. The engine will not run any different or have any more measurable blowby at 030 gap than 022.

2. Anything you do to make more power NA will make more power with boost. This includes adding stroke. Look up and watch a bunch of Richard Holdeners videos on you tube.

3. Depends on what fuel you are willing to run. 91 octane, e85, or methanol will all require vastly different compression ratios and different tunes. The first thing you should do before turning a wrench is pick your fuel, and that will dictate your compression ratio. There is no “optimal” compression ratio.
Click to expand...

Thank you for the info! I am reading and gathering as much information as I can.
 
TT5.9mag said:
Where to start? Ill go the simple route first. Put a turbo on the engine you have now. Get the fuel system up to task, and the turbo “kit” sorted out and I’ll bet it will meet your goals. A mild 360 with boost will sneeze 500 hp. That will give you the ability to learn all the intricacies of making it live on boost and do it on an engine you plan to replace anyway. Call it a sacrificial lamb but a tool that is invaluable. You’ll likely blow it up the first time around learning to tune it. Ask me how I know. But the knowledge will be well worth it. All the while building your forged bottom end stroker for boost and not trying to run it NA for a time which imo is a wasted effort. The book posted above by @Babyblue66 “supercharged” by Corky Bell is an EXCELLENT resource for any kind of boosted application, not just supercharging, and is great advice.
Click to expand...
I am not really sure why that idea never crossed my mind! It is interesting how simple ideas like that can slip the mind. I am concerned that my current motor was not gapped for boost or set up with a lower compression ratio. I will have to do some investigation on what the compression of my current 360 is.
 
MonkeyTrev said:
I am not really sure why that idea never crossed my mind! It is interesting how simple ideas like that can slip the mind. I am concerned that my current motor was not gapped for boost or set up with a lower compression ratio. I will have to do some investigation on what the compression of my current 360 is.
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Don’t get too greedy with the boost and you’ll probably be fine with your starter motor. The problem is, we all get greedy and want to turn up the psi. Lol
 
MonkeyTrev said:
I am not really sure why that idea never crossed my mind! It is interesting how simple ideas like that can slip the mind. I am concerned that my current motor was not gapped for boost or set up with a lower compression ratio. I will have to do some investigation on what the compression of my current 360 is.
Click to expand...
I’d spend one weekend, yank the engine, disassemble it, gap the rings, put on mls head gaskets and if the compression ratio is between 8:1 and 10:1 reassemble the entire thing, then stab it back in. It’ll cost time and gaskets. If it’s above 10:1 I’d either push for the same as above but run it on e85 exclusively or a piston change to run 91-93 octane. That combination should serve you well deep in to the 10-12 psi range and like I said above a mild 360 with 12 psi on top will sneeze 500hp. Just work your way up in boost while learning how to tune it and read plugs.
 
subcom said:
Don’t get too greedy with the boost and you’ll probably be fine with your starter motor. The problem is, we all get greedy and want to turn up the psi. Lol
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No truer words have ever been spoken. “Wow if 8 pounds is this much fun what would 12 be like?”
 
AJ/FormS said:
A 350hp, hi-compression 360 is a real blast. This is an easy/cheap/reliable build. Get's into the 12s real easy, on street tires with street gears. With overdrive she can get fabulous hi-way fuel mileage, and she's a go anywhere/anytime girl. In the early-A, she might do low 12s. That's a heckuva car.
As a streeter, I fail to see the allure of boost.
Click to expand...
It’s definitely a trade off and compromises have to be made but turbos can make for a great street car. Mine is a 5.9 with stock cast crank, 10.5:1 forged pistons, gapped rings, etc, etc. 3.23 gears, a very street friendly 9.5” converter and I can drive it 60 miles round trip to the track and click off not low 12s but high 10s or faster once I get it to hook.
Of course I have in my fuel delivery what it would cost to build a reliable 12s 360. I mentioned trade offs right? Lol
 
subcom said:
It’s definitely a trade off and compromises have to be made but turbos can make for a great street car. Mine is a 5.9 with stock cast crank, 10.5:1 forged pistons, gapped rings, etc, etc. 3.23 gears, a very street friendly 9.5” converter and I can drive it 60 miles round trip to the track and click off not low 12s but high 10s or faster once I get it to hook.
Of course I have in my fuel delivery what it would cost to build a reliable 12s 360. I mentioned trade offs right? Lol
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Your car is a great example of why turbos are as awesome as they are. But I’ll correct you and say “turbos DO make for a great street car”. I love your car. And having way too much fuel system is imperative to having a successful turbo car. You’ve done it right.
 
I 100% agree with boosting the current motor. I blew up 4 junkyard 5.3s figuring everything out. Granted it was all because of a certain coil type causing predetonation, however it would have really sucked to have scattered all the good parts. Also agreeing with TT5.9mag, you may not care for the LS which is fine, it was just what I had a lot of available to me, and it made sense in the horsepower per dollar argument even though I loved my 340. But everything else I did may benefit you with what you're looking to build for a street car as far as the chassis build and modern upgrades to make a good street driver that occasionally sees the strip. 780whp on 93 pump is fun as hell on the street too.

As Subcom said, you'll have a decent amount of money in your fuel system and engine management system as well. Unless you plan to go blow through carb, which is another can of worms that I'm sure a ton of guys can help with on here, you wont need a whole engine management system but there are still costs there like an ignition module that pulls timing per psi of boost etc. Good fuel and engine management is worth it on any build you want to put miles on though.

It will also help immensely if you can fabricate yourself. Not saying its impossible to do it if you can't, but just be prepared for that cost of the hot and cold side of the turbo setup if you're paying someone else. I highly recommend the 78/75 kit from VS Racing if you go turbo. Hundreds of guys are using it on the sloppy mechanics page that Matt Happel started and Matt worked with Viren building this kit. Its like $1300 for the turbo, intercooler, boots, oil supply and drain lines and universal intercooler piping. But you're quite a ways from there and this is just one persons recommendation.
 
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