Best 440 pistons?

[1meancuda]

So what is a better choice, the Keith Black hypereutic (spelling?) or the Speed Pro forged pistons? Once again, there is only about a $10 difference so I'm not concerned there. The plus side of the Speed Pro's is that they can give me the 8.5-9:1 compression ratio that I'm thinking about running. The KB's will go 9+:1.
Let's hear some opinions on these or other options that I should check out.

[Dart]

You need to consider the weight of the pistons also. Most of the forged pistons are 3 times as heavy as the KB pistons.

Some of the the KB Hyperutectic pistons are domed to get the proper quench clearance between the head and the piston on the non valve side wich gives you more efficeint combustion. The Hyperutectic pistons also hold more heat which leads to better combustion in the chamber as well.

Rember to set the clearances correctly (ring gap and bore) if you run the Hyper KB pistons.

[451Mopar]

The best piston is the one that works best in your application.
I don't know what your building, so I can not say.
The only information you posted is an estimated compression ratio?

There are reasons to use either piston, and reasons to not use either one of the pistons.

Here is some considerations:
The Keith Black pistons are a good choice for most street and street/strip engines that are normally asperated. They are reasonably light, inexpensive and come in many configurations and compression ratios. The cast hyperutectic (sp) allows a close bore fit so they run quieter than forged pistons.
The top piston ring location requires special care to gap the top ring per the Keith black instructions, but this also makes the piston thermally efficent.
The drawback of the design are when used with power adders like nitrous oxide, supercharging, and at very high RPMs.
The keith black pistons also have large valve reliefs for high lift cams.

The Sealed Power forged pistons will not be as quiet or as light, but can withstand more abuse. Usually these do not have valve reliefs which may need to be machined in. They also do not have a "quench" design when using open heads, and the heavy weight of the pistons can be a problem at high RPM.

Ross Forged pistons are lighter than either of the above pistons, and are very strong. These are good for engines that see higher RPM ranges and can handle some nitrous and blower applications (at least better than the other pistons above.) I mention Ross because they are reasonable priced, some even listed in the Jegs and Summit racing catalog for around $400/set.
One possable problem is I'm not sure Ross sell an off the shelf piston for low compression engines. They can custom build them, but then the cost goes up to $600+/set.

[dirty dan]

As 451 said it depends on what you have planed for the engine.
There isn`t any one piston to fit all aplications.
If there were everyone would be running the same pistons.
If you could supply a little more info you would get a more defind answer.

[1meancuda]

Opps!!! Sorry about that guys! I guess a little more info would have helped out a whole lot!
The engine is a 1978 440 with a 727 Torqueflight tranny. I will be using an Edelbrock Performer dual plane intake and a Performer 750cfm carb. The cam will be 224/234 at .050". Stock rods, crank, and heads will be used (*crossing my fingers!*). I haven't cracked open the engine yet to check the condition of the bores, but if they need it, I'll probably get the block .030 over.
If any other info is needed just give me a holler! This is my first rebuild so I'm kind of new to all this!

[dirty dan]

Ok now that we know what we are working with it would be a little eazier to help.
Now judgeing from your cam selection I assume you are biulding this engine for either towing or a nearly stock rebiuld.
In either event it will not be a race type application.
You should have no need for forged pistons unless you think
You may later want to play with some NOS.
How ever If you use the hypertech`s be sure to tell and show
your machinist the clearance instructions that come in the box.
(VERY IMPORTANT) as these pistons react diferantly to heat then most.

[deadhorse66]

My opinion is biased, but I'm going to give it anyway. I really don't care too much for Kieth Black pistons, and it is for all of the reasons mentioned before. I have seen the crowns pulled off of them, I have seen them melt like ice on a hot sidewalk, and I have seen them split in half when used in a high compression engine. I would select some type of forged piston for any type of engine I might subject to even a minute amount of abuse. Granted, they are a little heavier when you go with a Speed-Pro as compared to a KB, but in a street engine, this really doesn't matter too much. I can deal with the extra noise from the looser piston to wall clearance, because the forged pistons need it due to the fact that they transfer heat throughout the piston. A KB does not do this, and much of the heat stays at the top--this can contribute to detonation, and a KB will absolutely self destruct if it sees very much of that. For these reasons, and all of the above, I would pick the Speed-Pro. Just my biased opinion.

[Doug Wilson]

I would only use hypereutectic pistons for a stock rebuild for an engine I wanted to run for 200,000 + miles. If I didn't intend to keep the engine that long I'd use standard cast pistons. For ANY performance application, I'd use forged pistons, and probably not Speed Pro, or TRW.

My thoughts about it.

[Dart]

I totally diasgree with the posts on the KBs. They are good pistons and the problems stated are due to improper ring gap and piston clearance. The hyperutectic will take 100hp of NOS. The forged piston (TRW etc.) are heavy and old school. Granted if you are building a 700 hp monster you would want to use something a little more heavy duty, but the KBs are a excellent choice for a 400-500 horse B/RB.

[1meancuda]

Weight is not really a factor for me as this will not be making 1/4 mile passes. I really want to build this engine right so that it will stand up to years of daily driving. Perhaps concentrating on building a stout bottom end would be smart and the added strength of the forged pistons would justify the added weight.
I'm not going to run nitrous ever. In my mind, if you can't get were you want on motor, you shouldn't be there!!!
As for the cam selection, yes it's pretty small compared to some out there, but since the engine is a 1978, it's probably bigger than the stock one!

[Dart]

When I refer to weight of the pistons I am referring to reciprocating mass. A heavier piston will cause greater reciprocating weight which will make a difference in how fast the motor revs. The hyperutectic pistons also reflect heat which if set up correctly will allow for more complete burn in the cylinders. This is an area most people overlook adn the KBs can be matched to the quench inthe head which also helps combustion. If I remember correctly the KB hyperutectic pistons are about 1/3 the weight of a forged slug and cost about 1/2. i would seiously look at those pistons. The main problem is that most machinists do not set them up correctly which will lead to massive failure. I would not automatically discount using those pistons. I personally think they are a wise choice.

[Doug Wilson]

I'm never one to argue, but... the way you build the bottom end (and the rest of the engine) really depends on what you want to get out of it. I don't think anyone will tell you that the hyper pistons are as strong as forged pistons. If you drop a valve on a hyper piston, it will likely scatter the engine. If the same thing happens with a forged one, you at least have some chance that the damage will be limited, and you might even be able to re-use the piston.

I just don't see that the hyper pistons have any advantage over a cast piston in a street engine, and certainly none over a forged piston in a street or strip application. Again, I think they are best used in an engine you want to get many, many miles out of, at a fairly low mechanical stress level.

[1meancuda]

Wouldn't it be a true assumption that if you built the bottom end to with-stand the stress of drag racing, but you drove it on the street, it would basically be bullet proof?
The Speed Pro forged pistons are actually cheaper than the KB hypers and have a lower compression rating which would be prefect for my street engine. That is the biggest reason I'm leaning towards the forged. A low compression ratio with little fiddling around is perfect for me! I also get the added benefit of the added strength in case I would want to increase the power through a bigger cam or some other ways.

[bullet]

CP

[1meancuda]

I'm sorry but what does "CP" mean???

[Doug Wilson]

"Communist Party" ??

[deadhorse66]

Originally posted by Doug Wilson
I would only use hypereutectic pistons for a stock rebuild for an engine I wanted to run for 200,000 + miles. If I didn't intend to keep the engine that long I'd use standard cast pistons. For ANY performance application, I'd use forged pistons, and probably not Speed Pro, or TRW.
My thoughts about it.

Agreed. I don't think KBs are really so much stronger than a cast hypoutectic to justify the price. Speed-Pros have the durability thing on their side, and they are not so heavy to make any difference if you are not trying to build a 700hp monster, and for about the same price as a KB, I will take the stronger one. Like Doug says, they aren't the greatest, and like Dart says, they are old school, but they are not 3X heavier, and they aren't double the price. When it's a tossup between the KB and the Speed-Pro, I'm going to stick with the Speed-Pro.

ee: KB

[Doug Wilson]

Good thinking, altogether.

[451Mopar]

The keith black pistons work fine in normally asperated engines, and they have several features that are not avaliable on the speed pro pistons like large valve reliefs, Zero (or near zero) deck height, Quench dome design (for open heads), and the gas accumulator between the first and second rings which is supposed to help the rings seal better.

My friends low 12-second street charger ran the KB pistons for many years with no problems. I have also built two 360 engines with the KB pistons which ran very well.

Anyhow, the speed pro pistons are OK, but may not be cheaper if you need to pay for extra machine work (valve reliefs, decking, etc.)

[deadhorse66]

Originally posted by 451Mopar
The keith black pistons work fine in normally asperated engines, and they have several features that are not avaliable on the speed pro pistons like large valve reliefs, Zero (or near zero) deck height, Quench dome design (for open heads), and the gas accumulator between the first and second rings which is supposed to help the rings seal better.

My friends low 12-second street charger ran the KB pistons for many years with no problems. I have also built two 360 engines with the KB pistons which ran very well.

Anyhow, the speed pro pistons are OK, but may not be cheaper if you need to pay for extra machine work (valve reliefs, decking, etc.)

Agreed again. However, if I am set on building something that needs large reliefs and the like, I am going to buy a set of Ross or Diamond or Arias. I just don't like quench dome pistons because they are a way of trying to bandage the combustion problems encountered with an open chambered head. If I want to build a killer, it would have Indy closed chamber heads, Arias flat tops and Crower rods and crankshaft. I can't afford that so I will use doctored 906s, Speed-Pros and an otherwise stock rotating assy. Just my opinion.

[451Mopar]

I agree with you, I just wanted to say the KB pistons are a good deal for many engines (not as bad as you posted earlier), and that when it comes to price that you need to consider the cost of making the piston work for your engine combination.

Some examples:
I have TRW flat top forged pistons in my 383, but they have no valve reliefs. I have to pay eatra to have valve reliefs machined into the pistons, and this also lowers my compression ratio.
I have KB232 quench dome pistons in my 360 engine, but I had to pay extra to have the small end of the rods narrowed (unique to this piston, most KB pistons don't need this.)
I have Ross pistons in the 451 stroker engine, but I had to pay extra to have them dished to lower my compression ratio to 11:1(because my cylinder heads are only 65cc's.)

[1meancuda]

I thought that the Speed Pro's already have the the valve reliefs, but I guess I'll have to take a look at that.

[451Mopar]

Some TRW / speed-pro pistons have small valve reliefs, but many do not any reliefs at all, and sometimes if they do have the reliefs, they are too small for larger valve heads and cams.