Box Stock

Bracing the block??

W Lindsey said:
I agree there!!!!
Did either of you WinstonSmith or Sneaks make a template or drawings for your braces? I would love to get a copy of them if you did.
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No.....

Most of my stuff comes from templates made form cereal boxes and drawing on napkins and cigarete packs.

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Important thing is most of this is one off.
With the exception of the top plate most will not fit other blocks because the castings tend to be a little different from one to another.

Also:
I would like to thank Youngengines for his pictures too ( we need some reposts ).
Some things like my front end girdle are based on things he shared with me.
The oil plug as a point of anchor I lifted directly from him.
 
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sneaks12303 said:
Carb bracing . U can B creative here...
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Clever PoBoy.....
You have something new I need to think through.
Money is alsways something I have short of ( and time too )
But this is a good idea.
My carbs stick out and my intakes are heavy because I make them from steel JIC hydraulic fittings....
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I started making my own Phenolic spacers to keep the heat off the intake.
Maybe I can mmake something in some heavier phenolic that serves the same function.
Thanks for sharing Sneaks....
And thank you for the kind words.
I do try and make them look nice, but most people have a hard time seeing them from behind me all day lol.
 
The crank bracing is a great idea but the cylinder bracing IMO isn't necessary, if it's going to blow I'd rather it blow the top off and leave some good parts then pop inside the block and destroy everything. These chinese blocks aren't designed for what we're doing to them, and what happens is they try to seperate the cylinded from the crank case which means it's stretching and warping and if it's all braced up the jug isn't coming off and everything in the motor is going to be destroyed. I've seen them blow the top and hurt nothing but the block. If that block was braced everything is trash. I'm not saying that if the block comes apart everything is going to be fine but there's a much better chance of salvaging parts from a broken block then an internal disaster.
 
I don't race karts ( have not since the 80s ).
You fellows have better PPE and gaurdiing to protect you than we do.

My top plate is intended to keep the wedding tackle in one piece ( alternative to the alunimum top plate would have been an aluminum codpiece. this would have also required some bottomless chaps and handle bar mustache that the wife would not aprove of me thinks. And I don't race with those types of fellow, nothing against them hey its free country..... )
As a side benifit the bracing does improve the block.
If you are warping and twisting under load you are loosing cylinder presure and risking gasket failure.
The top plate and girdles will save you money and help hold everything tight for a better seal.
I can't prove this but I see less blow by in catch can under hard excelleration.

Trick is everthing must bolt on cold without stressing the block.
As the engine warms up the block expands but the added parts do not expand quite as much and help squeeze everything back as they try to stretch further in the opposit direction.
How much?
I would need a strain gauge to be sure but I suspect its signifiant.

On the other had if done wrong this might cause stress too.

I have mostly guessed what the best way to go about a gridle.
I could have it all wrong too.....
 
I hear ya on protecting the wedding tackle. That stuff flying around could make a he into a she real quick fast and in a hurry. LOL
 
I am alarmed by the number of people using the wrong billet parts like flywheels on the predator.
You kart fellows generaly have things dialed in tight for the track.
Your not over reving the engines.

But minibike racers are all over the place.
Some don;t use billet some use what ever they can find and gearing is anyones guess....

I talk about bracing and scatter shields but this is really not much help if they use a Honda flywheel on a Predator.
We got to get that out more than we are doing.
 
You are correct there Winston. Not only are they endangering themselves but others as well. I have seen first hand what a flywheel can do first hand. One on a Mercury Outboard that wuz a buzzin 13k when it let go. It wasn't pretty. The second time it was me on the wrong end of the stick. I have a momento scar and a weeks stay with the nurses. The best part wuz the nurses LOL
 
I have to say I haven't had a blow up in a braced block yet. I have had three before bracing, and I have pushed them further since then.
 
I've never braced one nor have I blown one, but I've seen them go. I've broken one crank and cracked one piston in three years not bad in my book, since I run the crap out of them and much harder than dragging them. We run 2.90 bores with stroker cranks and 2.99 bores with stroker cranks at 9000rpm+ over .400 lift for 20 laps at a time with welded up heads and 17:1 compression but if you think you need bracing then do what you thinks best it's just not necessary IMO.
 
youngengines said:
I have to say I haven't had a blow up in a braced block yet. I have had three before bracing, and I have pushed them further since then.
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Same here , With just some well thought out bracing, these utility motors will put out 20 alky hp at 8000rpms with reliability too...
 
your right in that, if it's going to blow, then girdles and bracing ain't gonna stop it....but if it will keep the block from cracking and blowing the jug off the piston (like i've see some pictures of), then what little weight the bracing adds is more peace of mind than anything. i've only had one engine go south on me....wait!!...i'm in the south, so it went north!!....the block cracked all the way around the cylinder and that's what popped...everything else was fine, but the block was in two pieces. in this case, the girdles/bracing would have helped....
 
Flash06 said:
I've never braced one nor have I blown one, but I've seen them go. I've broken one crank and cracked one piston in three years not bad in my book, since I run the crap out of them and much harder than dragging them. We run 2.90 bores with stroker cranks and 2.99 bores with stroker cranks at 9000rpm+ over .400 lift for 20 laps at a time with welded up heads and 17:1 compression but if you think you need bracing then do what you thinks best it's just not necessary IMO.
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I'm not that lucky...LOL. I have had two cranks break, but I had lightened them..wont do that again (they lived until I made more power)..I have blew three jugs off...but one was on my dual engine kart (when I first put it together)..it was making 18hp..and the other was over 20...so the other may have been making it do more than it could handle??? Its not that hard for me to do some bracing, so I will continue to do it.. I have yet to do a stroker.
 
rotflmao!! flash......that's jsut something that i wouldn't want to happen to anyone!! "scuse me...i think your stepping on my jigglies...can i have them back?"
 
mikey56 said:
your right in that, if it's going to blow, then girdles and bracing ain't gonna stop it....but if it will keep the block from cracking and blowing the jug off the piston (like i've see some pictures of), then what little weight the bracing adds is more peace of mind than anything. i've only had one engine go south on me....wait!!...i'm in the south, so it went north!!....the block cracked all the way around the cylinder and that's what popped...everything else was fine, but the block was in two pieces. in this case, the girdles/bracing would have helped....
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That's exactly what I'm saying mikey, if it's going to blow then it's going to blow. Like you said everything but the block was fine, just imagine if it blew internally with no escape then everything is just a scrap pile. Mikey we run tall chain guards between us and the motor for protection from not only the chain, but engine explosion and as a safety from the header pipe so we don't get burned. The extra crank support and bearing behind the flywheel is a great idea, but block bracing on a kart isn't necessary IMO.
 
WinstonSmith said:
I am alarmed by the number of people using the wrong billet parts like flywheels on the predator.
You kart fellows generaly have things dialed in tight for the track.
Your not over reving the engines.

But minibike racers are all over the place.
Some don;t use billet some use what ever they can find and gearing is anyones guess....

I talk about bracing and scatter shields but this is really not much help if they use a Honda flywheel on a Predator.
We got to get that out more than we are doing.
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It's mandatory that we run billet flywheels and I wouldn't have it any other way, our motors run in a lot of the over rev for several laps. There used to be a track a little south of me several years ago that was an up hill down hill track, you had to gear your kart for the up hill and just over rev the longer down hill side. At this track a flywheel came off and apart then flew into the crowd hit a man in the head and killed him, I believe that was one major contributor to the rule for billet flywheels to be mandatory on all karts racing in the wka. Not running a billet flywheel is a not so smart move.
 
I think we may have to agree to disagree on this one. I run karts too, and have had them blow the jugs off. I may have just had weak blocks. The cranks, rods pistons were all ok, which tells me they were not getting ready to give a problem..the block just couldn't take it. I agree with the weakest link going first, but the weakest link has been the block for me.. and believe me , I'm not easy on them either. We turned 8400 Friday night every lap, and 8800 Saturday..I have turned my latest build 10,200 on the dyno a few times, and 9000+ a pile
 
youngengines said:
I think we may have to agree to disagree on this one. I run karts too, and have had them blow the jugs off. I may have just had weak blocks. The cranks, rods pistons were all ok, which tells me they were not getting ready to give a problem..the block just couldn't take it. I agree with the weakest link going first, but the weakest link has been the block for me.. and believe me , I'm not easy on them either. We turned 8400 Friday night every lap, and 8800 Saturday..I have turned my latest build 10,200 on the dyno a few times, and 9000+ a pile
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From 6.5hp @ 3600r's to 25hp @ 10,000rpm's ...POBOY's have this figured out...
 
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