What do you guys think would have less flex. 5/16" steel, or 1/2" aluminum for a blower bracket plate ?

-- Joe

 

No comment on this?

-- Joe

 

5/16 should work fine, but if it was me I would bump it up to 3/8 plate if you have it.

1/2 Aluminum would work but be more costly. So depends on what you have on hand.

Is there a reason you're debating between Carbon steel and Aluminum?

And how do you plan to cut and fabricate the blower bracket? Torch? Plasma? Cut off wheel?

 

I'm making an adapter bracket that bolts to the head and the bottom of the block on the passenger side, and the plate will bolt to it. I'm planning on using a fox body blower plate. The question is, do I buy a steel one which is 5/16, or an aluminum one which is 1/2". The aluminum one is a little more money.

I also have a 3/8" steel vortech reinforcement plate. Basically, you sandwich shims between the blower plate and the re-inforcement plate.

If I had to cut or modify the blower plate, I'd probably use my band saw.

Once the adapter is done, I'll throw it on the bridgeport to make sure it's 100% parallel with the head.

So anyway, which plate would you order?



-- Joe

 

If it was me, I'd go with the aluminum plate due to weight and keeping it looking good. Plus since you don't plan on using any heat to cut it, and would use a band saw to modify if needed, aluminum would be the easiest to cut without affecting the plate that could affect its structural interigrety.

6061 1/2" aluminum plate weighs 7.056 pounds per square foot. While carbon steel 5/16" plate weighs 12.76 pounds per square foot. So it's almost 50% lighter in this case.

 

Sounds good. That was the type of answer I was looking for, thanks!

I'll order it today.

-- Joe

 

No problem, glad I could help. Good luck!

 

i made a bracket out of 1/2" aluminum. i cut some of it with a jigsaw since i dont have a vertical bandsaw. sloooooooooow going. i wound up plasma cutting the big sections out and then shaped it up the rest of the way with a bridgeport.
also, on the ysi, i had to reduce thickness in the middle of the U part of the bracket so it would fit behind the front 3 mounting bosses on the blower.

 

The 1/2" aluminum plate will be more rigid and lighter as mentioned.

 

steel tends to weigh about 2.5x as much as the same volume of aluminum, but it also tends to be about 2x the strength (of course this varies with the grade of both), so weight and stiffness will depend on the relative design of both brackets. Unless you get elaborate with your design the aluminum will likely be more rigid.

I've made them out of both, and aluminum is significantly easier to make them out of if you're limited by the tools that you have. Most woodworking tools will work OK in aluminum if you're careful/know some tricks. I've made 1/2" aluminum blower brackets using a table saw, router and drill press with good luck (it can be dangerous if you don't know what you're doing), but if you have things like a mill and a plasma cutter (which I do now, didn't when I made that bracket) it's pretty much irrelevant, both can be machined (again, somewhat depends on grade, some aluminum and some steel doesn't machine great, like chrome molly can be gummy to machine)

 

So, here is the deal.

I'm running the blower on the passenger side which required a custom intermediate bracket and mounting plate. I'm using standard vortech crank pulley spacer, 10 rib pulleys, etc so my dimensions are the same.

The intermediate bracket is made out of 3/8" plate bolted to the head, 2x3 1/4" square stock spacing out a second 3/8" plate. The second plate is what the blower plate bolts to. I completely stole the design from Gta324.

Now what concerns me, is my 3/8" blower plate only has 2 mounting holes so I wasn't sure if it would flex as the blower will have a lot of leverage on the bracket. My other option was to buy a 1/2" alum fox body bracket, which has more material to attach. I could get 3 bolts by the head evenly spaced. See attached images.

Notice on the third image, which is where I want the head unit to be, that if I use the steel 3/8" blower plate I've basically got to really offset how it mounts to the head intermediate bracket. If I use a 1/2" aluminum one from a fox body, I've got more material to the right that will sit in front of the head I think.

-- Joe

 

Nothing?

 

To be honest with you your written description is hard to follow, I'm not sure where the 5/16" from the original question comes in, and the pictures aren't that informative (though I bet if I was standing there and you pointed at what you were trying to do it would take 30 seconds to understand).

What _I think_ you're asking about is the stiffness of the front bracket/plate between your spacer and the head unit. If that's the case, looking at what you have I don't think you'll have any stiffness problems with the front plate/bracket (most of the forces there are inline with the mass of the bracket/plate as long as the spacer/head mounting plate are doing their jobs and not flexing), but the head mounting plate/spacer will be an issue, any flex there will change both the blower's position and the pulley alignment which will typically only show up under conditions that you typically can't see. Did that welded up steel spacer/plate work well on the other side? seeing that my feeling is that it doesn't distribute the load over a large enough area on the head to be stable, even though the steel is pretty heavy. Without at least 3 mounting points on the engine and some pretty serious mass to the inside of the axis of the blower shaft the only way I see that not flexing is if you have some sort of additional bracket/brace on the outside back of the blower in tension (kind of like the brackets that mount to the exhaust studs on SBC v-belt AC setups, something to keep it from flapping around on the back side).

My feeling is that for the front plate it could be fairly thin (like 1/4" steel would do) as long as you're not using it to position a tensioner also, that's one thing that will put a twisting force on it, but the plate mounted to the engine and the spacer is where you're going to end up with rigidity problems (I can think of 2 setups that I've worked on that ended up with machined plates in the 1" thick range where they mounted to the engine before things were stiff enough to be really reliable).

Also, for it to be reliable using typical alloys of steel and aluminum, the aluminum assembly will have to be more rigid, since any flexing in the aluminum will work harden the aluminum causing it to crack/break faster than the steel.

That being said, I'm not sure if I've answered (or even really) understood your question correctly.

 

the vortech bracket I am using connects the top 3 bolts to the accessory holes in the head, then 2 bolts down low at the bottom of the block. Look at the attached pic of the bracket. I would try and use those top 3 holes and run the bracket/plate down to at least one of those holes on the block. if you only use the top 3 holes, then I would think you would need to support it with more bracing somewhere else (to water pump, or frame, etc). Remember, the blower and pulley isn't light, and vortech used all 5 mounting holes available on the sbc engine block for their bracket. I would make it as stiff and secured as I could the first time around.

 

Here is a picture of my 3/8" steel bracket.

What I was getting at was, notice how I have very little material to bolt to the blower bracket. Even if I drilled more holes than the two, it's really only covering a few square inches in front of the head.

My thoughts were, will this bracket flex too much and should I try to get one that is longer.

Or Will it be fine?

-- Joe

 

Here is an overlay of the Aluminum bracket vs my steel one. See how we have more area to bolt things to?

I'm thinking I can get two bolts on the top which would go to the head bracket, and maybe one or two bolts on the bottom that could go to the block.



-- Joe

 

seeing that I would use the steel. after you add the blower, intercooler, pipes, couplers, and all of the bolts that hold that stuff together, you are adding a bunch of weight, saving some weight between alum vs steel doesn't seem important in the big picture. you also don't want to have to re-make this bracket because you find out if flexes later on. I would use the steel one (one on the bottom) as it looks to be more 'stable' with more surface area.

 

The 3/8" Steel bracket is the black painted one. The aluminum one is the metal colored one.

-- Joe