5.2/5.9 H.P build guesstimate

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Your right! I’ll probably use the play dough method,

I like and suggest clay. Play-do is a bit more pliable.
should I just reuse the factory gasket torqued to spec because it’s probably way more thinner than the replacement I will use,.

The reuse of the OEM gasket for checking purposes is fine. I’ve reused head gaskets over and over. A new one is always a good bet. Cometic can get you the thickness you want if it is not commercially available.
that way if I have clearance with that gasket I should be fine with the after market one.

I check without gaskets.
I doubt you’ll have a problem.
 
It is worth mentioning the 280h cam selected for the 318 build will be a dog on the bottom end if you don't follow the rest of the build and the compression up.
Years ago we used that in a 350 chebbie with stock low compression pistons and a stock converter in an 81 pontiac grand prix with 373 gears. Dead off the line. My 360 with much less cam and equally shitty compression destroyed it drag racing in route 8.
Something arrund the comp 262h probably would have been better for our application.
And the 350 has the advantage of cubes.

At the stock compression of the engine, I’d call it OK. I’d rather see another point of compression myself. It’s not the end of the world though.

The 380/360 engine, much like what’s being built here, the key for performance is a properly stalled converter, gears & tire size that also work with the weight of the car which is really the bigger problem no one seems to see or address.

Everyone would rather, as it seems, to bludgeon the engine/cam size as a dog and even more so through members that have had or have the engine for n a heavy car with inadequate converter stall and gears often in a car that has not an ideal weight.

I agree that a smaller cam would be better for general street driving and mild performance, but I can’t make the call it will make the asking HP or performance goal he’s looking for.
 
At the stock compression of the engine, I’d call it OK. I’d rather see another point of compression myself. It’s not the end of the world though.

The 380/360 engine, much like what’s being built here, the key for performance is a properly stalled converter, gears & tire size that also work with the weight of the car which is really the bigger problem no one seems to see or address.

Everyone would rather, as it seems, to bludgeon the engine/cam size as a dog and even more so through members that have had or have the engine for n a heavy car with inadequate converter stall and gears often in a car that has not an ideal weight.

I agree that a smaller cam would be better for general street driving and mild performance, but I can’t make the call it will make the asking HP or performance goal he’s looking for.
Oh no doubt. More gear and a better convertor would fix a lot of the lack of power off the light.
But wouldnt that mostly because these would allow the engine to Rev quicker into its preferred power band?

It is hard to make suggestions to other people when ever if they give certain goals they desire no two people have the same perspective.
My idea of a hot street car is a slow joke compared to someone else's idea of a hot street car.
 
It is worth mentioning the 280h cam selected for the 318 build will be a dog on the bottom end if you don't follow the rest of the build and the compression up.
Years ago we used that in a 350 chebbie with stock low compression pistons and a stock converter in an 81 pontiac grand prix with 373 gears. Dead off the line. My 360 with much less cam and equally shitty compression destroyed it drag racing in route 8.
Something arrund the comp 262h probably would have been better for our application.
And the 350 has the advantage of cubes.
Hey! Yeah I’m going with the 360 Magnum engine which has true 9:1 compression the car will have 3000 stall converter and 3.91 gear set at the drags and 3.55 on the street
 
Hey! Yeah I’m going with the 360 Magnum engine which has true 9:1 compression the car will have 3000 stall converter and 3.91 gear set at the drags and 3.55 on the street
I love magnum 5.9's but are the magnums a legit 9:1? Every one I've pulled apart has a dished piston about .040 down below deck height?
 
I love magnum 5.9's but are the magnums a legit 9:1? Every one I've pulled apart has a dished piston about .040 down below deck height?
Probably not but there higher than an LA, compression matters, but unless were talking two or more cr points difference, were probably talking under 20 hp. The magnum head is were most of the hp gain is coming from.

Airflow is hp, lower cr is just gonna be slightly less efficient at turn that airflow into power. So you need more air and probably rpm to make similar power.
 
Probably not but there higher than an LA, compression matters, but unless were talking two or more cr points difference, were probably talking under 20 hp. The magnum head is were most of the hp gain is coming from.

Airflow is hp, lower cr is just gonna be slightly less efficient at turn that airflow into power. So you need more air and probably rpm to make similar power.
Agreed.
But I just think it is important to know not to trust published compression ratings when choosing other parts for a combo.
 
Agreed.
But I just think it is important to know not to trust published compression ratings when choosing other parts for a combo.
True

People say cr is one of the reasons a magnum seems responds a bit better than a LA engine to a basic cam, 4bbl, header swap, I don't know that for sure but we do know the magnum response well to these mods and can get over 400 hp without any head mods.

I'd like to see similar cams etc.. ran through an LA an see what it dynos. Seems like it's probably about 20-30 hp down to a stock magnum.
 
Oh no doubt. More gear and a better convertor would fix a lot of the lack of power off the light.
But wouldnt that mostly because these would allow the engine to Rev quicker into its preferred power band?

Thats the main idea. Thats what needs to be done, thats what your supposed to be doing.

That part of the statement sounds like that’s a problem. Or a draw back hurting drivability or something.

A good modern quality converter will not be a draw back or leave you with a miserable dread spot down low. The lack of engine torque will do that by itself, not the converter.
It is hard to make suggestions to other people when ever if they give certain goals they desire no two people have the same perspective.
My idea of a hot street car is a slow joke compared to someone else's idea of a hot street car.
I agree
I love magnum 5.9's but are the magnums a legit 9:1? Every one I've pulled apart has a dished piston about .040 down below deck height?

Break out the calculators!
Agreed.
But I just think it is important to know not to trust published compression ratings when choosing other parts for a combo.

While a higher compression ratio makes the engine more efficient not only in drawing in the airfield charge, but also extracting more under the compression stroke. The problem here is, not an ideal amount of compression from where I stand at in my opinion, it’s not the end of the world.

Proof is in the pudding, correct? In that case, I guess you really have to look no father than when Dodge was entering in the new truck series back in the day. Actually, any other competitors were limited to a 9.01 compression ratio. If the race trucks are limited to this ratio, then how do you explain that making over 700 hp?!?!

The trick is airflow in airflow out!
We all know that the modern engines have superior cylinder heads. The hemi, the LS and the coyote. The current hemi engine has sold the heads that flow 300 CFM as cast. This is huge. This we all know I remember right? And this is why those engines perform so well and respond amazingly with simple camshaft changes, and basic bolt on like a better header over the exhaust manifold.

The main trick is to keep the air velocity up. This is simply not over, porting the cylinder head or putting two crate of his own head on top. If the cylinder head becomes too large for the displacement, the low and power starts to suffer while top and power starts to pick up.

Under the current offering for a magnum motor, this is pretty much impossible to do.

For the LA motor, while it’s possible, it’s more of a huge and obvious mismatch like putting a set of fully ported Indy heads or set of fully ported W9’s on a 273 engine.

There are too many people here that point to other peoples works and they themselves haven’t done jack **** and think they know what they’re talking about. Do your own investigation work which is not really here but elsewhere and pay attention, really screw eyes what’s going on. And then talk to the actual people that have been there and done that instead of the moron above.
 
Me :)
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Oh yes everything will be measured as always no guessing game, I’m just stuck between two cam choices right now,

222/228 @ 50 277/283 .494/.515

And the 230/236@50 282/290 .515/515

I was thinking if I port the heads a bit, add a windage tray, and up my compression to true 9:5
The smaller camshaft might work for me especially if I plan to drive this thing to work sometimes lol.
 
Oh yes everything will be measured as always no guessing game, I’m just stuck between two cam choices right now,

222/228 @ 50 277/283 .494/.515

And the 230/236@50 282/290 .515/515

I was thinking if I port the heads a bit, add a windage tray, and up my compression to true 9:5
The smaller camshaft might work for me especially if I plan to drive this thing to work sometimes lol.
You'll probably be happier in the street with the 222° cam.
 
At what Rpm range would you think I would be making Peak H.p hoping some where before 6200 and idling at least at 10inches of vacuum lol
You'll probably be happier in the street with the 222° cam.
 
At what Rpm range would you think I would be making Peak H.p hoping some where before 6200 and idling at least at 10inches of vacuum lol
My crate with a 230° cam supposedly peaks at 5400 rpms can't see yours being much different.
 
Either way you need converter and gears. I wouldn't think twice...I'd go with the bigger stick. Slightly steeper gears, slightly higher stall converter.
 
Either way you need converter and gears. I wouldn't think twice...I'd go with the bigger stick. Slightly steeper gears, slightly higher stall converter.
Yes I have 3.55 for the street and 3.91 for track and a 3000 stall convertor
 
Yes I have 3.55 for the street and 3.91 for track and a 3000 stall convertor
That's the problem with these questions, neither is the right or wrong choice, question is what's the best choice for you, everyone levels of compromises is gonna be different, it's just a guess which cam you'll prefer, same with every other choice. Some people are super sensitive how it performs down low others could careless as long when they drop the hammer at 20 mph it takes off like a rocket ship.
 
Yes I have 3.55 for the street and 3.91 for track and a 3000 stall convertor
3000 ain't enough. Those off the shelf "3000 stall" converters need a good bit of low end grunt to actually flash to 3000.

Who changes rear end gears for one use or another?
 
3000 ain't enough. Those off the shelf "3000 stall" converters need a good bit of low end grunt to actually flash to 3000.

Who changes rear end gears for one use or another?
Wasn’t off the shelf had it custom made by edge Performance, and I change gears whenever I find it necessary, trip to the drags or highway crusin.
 
My uncle use to change gears for different purposes, he'd put 3.23 in to go to the cottage and tow a boat with his built 340 Duster.
 
Wasn’t off the shelf had it custom made by edge Performance, and I change gears whenever I find it necessary, trip to the drags or highway crusin.
I would think that changing gear ratios could get expensive as that's new lube ever change
 
At what Rpm range would you think I would be making Peak H.p hoping some where before 6200 and idling at least at 10inches of vacuum lol
No way in hell that 230/236 cam in 360 inches at 9:1 compression pulls 10 inches of vacuum at idle. Just my opinion.

Maybe, maybe if it was ground on a 115 LSA or more I could do that.
 
No way in hell that 230/236 cam in 360 inches at 9:1 compression pulls 10 inches of vacuum at idle. Just my opinion.

Maybe, maybe if it was ground on a 115 LSA or more I could do that.
Re read the post not going with that camshaft going with a smaller one lol
 
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