KB Performance Pistons not backing their product.

[1969chargerrtse]

Anyone use or know of KB Performance pistons ( I saw a made in Mexico sticker on the box ) ?  This is why my motor is held up over a month.  Seems one of the 20 over pistons was 5k under size so my engine guy asked for a replacement.  The company would not replace their useless product so my engine guy finally talked the warehouse he deals with to absorb the cost.  We are still waiting for the new sets to arrive.  So while I worked my butt off in freezing weather to have the car ready for an engine.  I have nothing  .  Just wondering if any of you had any issues or like the product? 

[my73charger]

A friend of mine had the KB hypereutectic pistons in his 440 and one of the pistons came apart and detonated his engine.  He was 1/4 mile racing with it though so it was being used hard.  That is the only experience I have had with them though.   

[1969chargerrtse]

A friend of mine had the KB hypereutectic pistons in his 440 and one of the pistons came apart and detonated his engine.  He was 1/4 mile racing with it though so it was being used hard.  That is the only experience I have had with them though.   

Oh thats comforting.

[firefighter3931]

I'm not a KB piston fan allthough many run them with success on the street and in mild strip applications. It's VERY important to have the correct piston to wall clearance and top ring end gap dialed in to the recommended specs or you will have a failure. The KB hypers don't like detonation and are not as forgiving as a forged piston to a poor tune-up.



Ron

[1969chargerrtse]

I'm not a KB piston fan allthough many run them with success on the street and in mild strip applications. It's VERY important to have the correct piston to wall clearance and top ring end gap dialed in to the recommended specs or you will have a failure. The KB hypers don't like detonation and are not as forgiving as a forged piston to a poor tune-up.



Ron

I was hoping you would know something.  That's why he wouldn't put it in.  He could of and I would of known nothing, but he said it would affect ring gap and he won't do that.
Basically you're saying make sure the engine doesn't ping ?

[firefighter3931]

Basically you're saying make sure the engine doesn't ping ?

Exactly....detonation will cause the top ring land to break off and result in piston and possible engine failure. Your machinist is on top of things and doing a good job. 

You'll want to be diligent when tuning this engine....if the carb is too lean or the timing too agressive the problems will start. You need to get the tuneup right.... from the very beginning. 



Ron

[kamkuda]

I have been running KB's for a couple years in my 408.  All is good but it is a mild street engine. (There were few reasonable options for pistons when I had it built as 408's were a new thing back then).  If I had to do it again I would get forged.  If you have KB's  I would use them and ensure your top right gap is file fit correct.

My timing has been off, A/F has lean and fat, wires crossed etc.  It doesn't mean you will destroy a piston right away, it is just less forgiving.

[1969chargerrtse]

I have been running KB's for a couple years in my 408.  All is good but it is a mild street engine. (There were few reasonable options for pistons when I had it built as 408's were a new thing back then).  If I had to do it again I would get forged.  If you have KB's  I would use them and ensure your top right gap is file fit correct.

My timing has been off, A/F has lean and fat, wires crossed etc.  It doesn't mean you will destroy a piston right away, it is just less forgiving.

Everytime I see a response to this thread I cringe thinking it's negative.  My car will be nothing more than a cruisemobile.  My hot rod days are long over, just looking to sound and look mean.  Thanks for the positive comments.

[Runner]

about 100 passes  plus alot of street miles on my kb's  hyper pistons in my 3800 pound 71 roadrunner.    i had 2 choices when i biult mine,  either a ross piston for 550 dollars or a set of kbs for half the price ( i used the the 400 rods in my lowdeck stroker and most shelfed pistons are for 440 rods). i  the thing about hyper pistons is, like anything they need to be used in the application they are intended for. plus the ring gaps need to be set correctly.   my best pass has been 11.35@ 119 mph.     the kbs will be fine as long as you set the ring gaps up right.

  heres a pic of my kbs as they arrived, the second pic is after my machinest cut the quench dome off sence i was planning to upgrade to edd heads  at a later point and wanted to run the closed chamber e heads ( and did  4 monthes later)

[Just 6T9 CHGR]

A friend used them in his 440 with no trouble.  Like others said the ring gap is critical to their life

[firefighter3931]

Well, I've had enough.  I'm calling him this evening.  Either give me my motor back in pieces and will hammer out price later.  Or return those defective pistons to the supplier and get me another brand.  I worked my butt off all this winter to have this car ready by Feb at the latest.  Here I sit waiting, I've had enough I want to move on.  Forget the 20 over size, punch it out 30 or 40 over and get another brand and lets move on.    I dropped that motor off in what, November?  October?  Come on!!!!   Robby has had it.  I'll update on the conversation after I call him.

I would opt for the speedpro 2355 forged pistons....they're indestructible ! The 2355's weigh almost identical to the factory cast piston so balancing will be easy and economical. These pistons will produce a static compression ratio of approx. 9.3:1 with the open chambered iron heads....perfect for pump gas. 

Have the machinist rework the rods and install ARP rod bolts and balance the whole rotating assembly. You'll have a bulletproof bottom end that will last for years. 



Ron

[Runner]

  i wonder if your getting the run around from your machine shop.  mabe he screwed up the bore on once cylender?.    have your tryed to call kb yourself even iif you had to by the one piston it wouldnt cost much.    i agree  get a different brand and move on. 

[1969chargerrtse]

I trust no one more than this guy, he is absolutely the best of the best.  He's as frustrated as me. I called him today.  The supply shop swears it will be there Thursday.  He feels terrible about the hold up and said it's holding him up as his machine has my block strapped to it.  I trust him 100% and understand people not knowing him wondering, but I've know him for decades and he did my 396 Camaro pace car motor back in the 80's.  So we wait again, and lets see what Thursday brings.  Bottom line KB would not cover their off size part and the supply house is eating it for him.  He could of punched it 30 or 40 over but he said he wanted to save the block by going 20 over and ordering these pistons.  I asked what he meant?  He said by going 20 over it can be punched out again later if ever needed.  I'm sure I'll be dead by that time as I just want to cruise in it and put on 2,000 miles or so a year.  Being 51 odds are it'll outlast me.

[Runner]

i complete understand how you feel about your machinest, i trust mine the same way! good luck with your biuld

[Challenger340]

Sounds like you've got a good machine Guy on you side ! Not enough of them left !

I haven't had any problems with the KB's in Street and "milder" Strip applications. They have been just fine !
This Horse has been beat to death, but, again, proper "fit" and ring "endgap" are critical to longevity.
Also, adequate Engine Tune, to maintain NO detonation is also Big factor.

That said, Like Ron says, "the 2355 is indestructible", and far more forgiving of "inadequate" Tune jobs and detonation.

You can beat a 2355, "like a red-headed stepchild"

Bob out.

[1969chargerrtse]

Rob in.  O.k, here's the scoop.  Finally the supply house took back the pistons, and Federal Express delivered a new set of Federal Mogul? pistons.  They were 125.00 more and are standard replacement pistons for this motor.  Remember I'm nothing more than a cruise guy so I'm happy with that.  I told my engine guy about all the comments about the ring gap on the KB's.  He knew all about it, what type they were, how they heat up what they can do and not do.  What is recommended about grinding ring gaps etc, etc, etc...  This guys is the best of the best and said he will be down at his shop all this weekend putting it together.  He said this is why he had to get a day job.  My motor has been strapped to his bore machine for weeks waiting for this mess to clear, and he can't afford to wait either.  Thanks for all your help, and dear God don't say anything on the negative side on the replacement pistons I'm getting.  He said they are really made by Sterling?  Whatever, just slap her together.

[firefighter3931]

Rob in.  O.k, here's the scoop.  Finally the supply house took back the pistons, and Federal Express delivered a new set of Federal Mogul? pistons.  They were 125.00 more and are standard replacement pistons for this motor.  Remember I'm nothing more than a cruise guy so I'm happy with that.  I told my engine guy about all the comments about the ring gap on the KB's.  He knew all about it, what type they were, how they heat up what they can do and not do.  What is recommended about grinding ring gaps etc, etc, etc...  This guys is the best of the best and said he will be down at his shop all this weekend putting it together.  He said this is why he had to get a day job.  My motor has been strapped to his bore machine for weeks waiting for this mess to clear, and he can't afford to wait either.  Thanks for all your help, and dear God don't say anything on the negative side on the replacement pistons I'm getting.  He said they are really made by Sterling?  Whatever, just slap her together.

Just my opinion...but the 2355 forged pistons is what i would use, not a cast replacement slug. The Sterling pistons will most likely be a low compression piston that will leave you wanting. 



Ron

[Just 6T9 CHGR]

Rob in.  O.k, here's the scoop.  Finally the supply house took back the pistons, and Federal Express delivered a new set of Federal Mogul? pistons.  They were 125.00 more and are standard replacement pistons for this motor.  Remember I'm nothing more than a cruise guy so I'm happy with that.  I told my engine guy about all the comments about the ring gap on the KB's.  He knew all about it, what type they were, how they heat up what they can do and not do.  What is recommended about grinding ring gaps etc, etc, etc...  This guys is the best of the best and said he will be down at his shop all this weekend putting it together.  He said this is why he had to get a day job.  My motor has been strapped to his bore machine for weeks waiting for this mess to clear, and he can't afford to wait either.  Thanks for all your help, and dear God don't say anything on the negative side on the replacement pistons I'm getting.  He said they are really made by Sterling?  Whatever, just slap her together.

Just my opinion...but the 2355 forged pistons is what i would use, not a cast replacement slug. The Sterling pistons will most likely be a low compression piston that will leave you wanting. 



Ron

oooh....I definitely agree with Ron on that one.  I went with the 2266 SpeedPro forged pistons....I think they are the step below the 2355's

I used them because of my closed chambered 915 heads I am running....puts me at a nice streetable, cruiseable 9.3:1

[1969chargerrtse]

Rob in.  O.k, here's the scoop.  Finally the supply house took back the pistons, and Federal Express delivered a new set of Federal Mogul? pistons.  They were 125.00 more and are standard replacement pistons for this motor.  Remember I'm nothing more than a cruise guy so I'm happy with that.  I told my engine guy about all the comments about the ring gap on the KB's.  He knew all about it, what type they were, how they heat up what they can do and not do.  What is recommended about grinding ring gaps etc, etc, etc...  This guys is the best of the best and said he will be down at his shop all this weekend putting it together.  He said this is why he had to get a day job.  My motor has been strapped to his bore machine for weeks waiting for this mess to clear, and he can't afford to wait either.  Thanks for all your help, and dear God don't say anything on the negative side on the replacement pistons I'm getting.  He said they are really made by Sterling?  Whatever, just slap her together.

Just my opinion...but the 2355 forged pistons is what i would use, not a cast replacement slug. The Sterling pistons will most likely be a low compression piston that will leave you wanting. 



Ron

I hear ya, Money was an issue from the start, so thats why he went this way.  Look what time has been lost?  How the heck would I tell him after all this to send those back?  I'm only looking for  a stock engine here.  375hp not a hp more.  So If those slugs are what it came with in 69, thats fine with me.  Thanks for your advise.  Hp, spinning tires is not a want, just a Mopar rumble cruise.

Remember no negs, I can't take the stress.

[firefighter3931]

Rob in.  O.k, here's the scoop.  Finally the supply house took back the pistons, and Federal Express delivered a new set of Federal Mogul? pistons.  They were 125.00 more and are standard replacement pistons for this motor.  Remember I'm nothing more than a cruise guy so I'm happy with that.  I told my engine guy about all the comments about the ring gap on the KB's.  He knew all about it, what type they were, how they heat up what they can do and not do.  What is recommended about grinding ring gaps etc, etc, etc...  This guys is the best of the best and said he will be down at his shop all this weekend putting it together.  He said this is why he had to get a day job.  My motor has been strapped to his bore machine for weeks waiting for this mess to clear, and he can't afford to wait either.  Thanks for all your help, and dear God don't say anything on the negative side on the replacement pistons I'm getting.  He said they are really made by Sterling?  Whatever, just slap her together.

Just my opinion...but the 2355 forged pistons is what i would use, not a cast replacement slug. The Sterling pistons will most likely be a low compression piston that will leave you wanting. 



Ron

I hear ya, Money was an issue from the start, so thats why he went this way.  Look what time has been lost?  How the heck would I tell him after all this to send those back?  I'm only looking for  a stock engine here.  375hp not a hp more.  So If those slugs are what it came with in 69, thats fine with me.  Thanks for your advise.  Hp, spinning tires is not a want, just a Mopar rumble cruise.

Remember no negs, I can't take the stress.

Rob,

The motor is all apart....what's a few extra days to get a set of Speedpro pistons shipped from Summit going to hurt ? Now is not the time to be making mistakes with this build. 

You won't be building a 375hp motor with those pistons....it'll be more like a late 70's "smogger" slug. There have been many, many, many posts on here asking how to improve the performance of a low compression turd and the simple answer is allways a better piston. You're cripling the performance of that engine with a low compression piston and trust me....you will be disappointed with the performance. 


I'm just trying to save you from the "why can't my car beat a Yugo" thread next summer. I sure as hell don't wan't to have to be saying "i told yoo so" 

Listen, the problem with this build was not yours....it's the supplier. Don't feel pressured by anyone to get it done.....just for the sake of getting it done....PERIOD. Spend the extra $100.00 and do it right....the first time. 

Sorry buddy, but you asked for opinions so that's mine.....



Ron

[1969chargerrtse]

Rob,

The motor is all apart....what's a few extra days to get a set of Speedpro pistons shipped from Summit going to hurt ? Now is not the time to be making mistakes with this build. 

You won't be building a 375hp motor with those pistons....it'll be more like a late 70's "smogger" slug. There have been many, many, many posts on here asking how to improve the performance of a low compression turd and the simple answer is allways a better piston. You're crippling the performance of that engine with a low compression piston and trust me....you will be disappointed with the performance. 


I'm just trying to save you from the "why can't my car beat a Yugo" thread next summer. I sure as hell don't want to have to be saying "i told yoo so" 

Listen, the problem with this build was not yours....it's the supplier. Don't feel pressured by anyone to get it done.....just for the sake of getting it done....PERIOD. Spend the extra $100.00 and do it right....the first time. 

Sorry buddy, but you asked for opinions so that's mine.....



Ron


I want you to know I was up all night because of that slug comment.  I just couldn't sleep.  If it's as you say that sucks.  I would think I would be back at the standard 375hp motor?  I will print this out and read it to him after work and go with, why wasn't I asked what pistons I want in it.  I don't know how it will go, and it already cost me 125.00 more just to get the slugs but I'll call him and we'll see, and again I'll wait.  With all the fuss with the supplier and then finally getting them, and then asking to return them, oh man.  I don't think the supplier will refund anyway so I will lose that money, then have to spend more?  Thanks for the advise.  I did tell him just go stock.  I took a quick look and those pistons were at least another 450.00.  Not sure that's worth a divorce.

[no318]

For what it is worth.... I recently looked EVERYWHERE to find a set of speed pros.  They are not making them right now, and pistons in general are hard to find.  Unless you want the odd ball stuff like .040 or .060 or low compression, etc.  I heard from 2 machine shopw that there is a "piston shortage" at present. 

I do definately agree that a saving a few dollars here is not the place to do it. 

[firefighter3931]

For what it is worth.... I recently looked EVERYWHERE to find a set of speed pros.  They are not making them right now, and pistons in general are hard to find.  Unless you want the odd ball stuff like .040 or .060 or low compression, etc.  I heard from 2 machine shopw that there is a "piston shortage" at present. 

I do definately agree that a saving a few dollars here is not the place to do it. 

Mancini has them listed on their website for under $400.00 

http://chucker54.stores.yahoo.net/440comdis20s.html



Ron

[The70RT]

Like the pros said - I would go with a forged piston no matter what I was going to be doing with it. It is just an insurance policy as far as I am concerned.  May prevent a divorce if you pop a slug and it cost you another couple grand.

[defiance]

Rob,

The motor is all apart....what's a few extra days to get a set of Speedpro pistons shipped from Summit going to hurt ? Now is not the time to be making mistakes with this build. 

You won't be building a 375hp motor with those pistons....it'll be more like a late 70's "smogger" slug. There have been many, many, many posts on here asking how to improve the performance of a low compression turd and the simple answer is allways a better piston. You're crippling the performance of that engine with a low compression piston and trust me....you will be disappointed with the performance. 


I'm just trying to save you from the "why can't my car beat a Yugo" thread next summer. I sure as hell don't want to have to be saying "i told yoo so" 

Listen, the problem with this build was not yours....it's the supplier. Don't feel pressured by anyone to get it done.....just for the sake of getting it done....PERIOD. Spend the extra $100.00 and do it right....the first time. 

Sorry buddy, but you asked for opinions so that's mine.....



Ron


I want you to know I was up all night because of that slug comment.  I just couldn't sleep.  If it's as you say that sucks.  I would think I would be back at the standard 375hp motor?  I will print this out and read it to him after work and go with, why wasn't I asked what pistons I want in it.  I don't know how it will go, and it already cost me 125.00 more just to get the slugs but I'll call him and we'll see, and again I'll wait.  With all the fuss with the supplier and then finally getting them, and then asking to return them, oh man.  I don't think the supplier will refund anyway so I will lose that money, then have to spend more?  Thanks for the advise.  I did tell him just go stock.  I took a quick look and those pistons were at least another 450.00.  Not sure that's worth a divorce.

For reference, I actually ran those pistons for a year or so.  Had the car on a chassis dyno show around 215HP/300TQ with EFT, all MSD ignition, Performer intake, very mild ported 906 heads.  It was OK, but didn't "feel like a 440".  The things sit like .100 or .110 in the hole with stock deck/rod/crank!  I think I figured the compression at like 8.1:1 or something like that.

Having said that, this it drove fine, it sounded great, and it would still break the tires loose if I wanted it to!  

Still, the disappointment was enough that as soon as I had a head gasket go, I used it as an excuse to start a MAJOR rebuild (still ongoing )