BBC CHEVY 496 WISECO FORGED PISTONS 4.320 070 OVER +20cc DOME KP441A7
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WISECO FORGED PISTONS 4.320 BORE SIZE FOR BBC 496 ENGINES, +20cc DOME TOP FOR USE WITH 6.385 BUSHED OR PRESS FIT RODS, H-BEAM OR I-BEAM.
Our custom made Wiseco pistons are rated very high in the street/strip performance industry. Wiseco normally offer several grades of pistons, starting with the lower grade Pro-Tru Street version made with 4032 forged alloy. The next level up would be the professional series that are much more expensive and made from 2618 aircraft alloy and have fully machined crowns rather than the as cast crowns that are on the Pro-Tru series. Our Wiseco pistons are custom made for us, and have both of these premium features, 2618 Alloy, and fully machined crowns. All premium grade forged pistons on the market have these two unique features and usually cost around $800-$1100 per set.
We have built approximately 6000 engines using the Wiseco pistons over the past 10 years. The engines have been for street rod and strip use. We have seen no problems, nor have there been any complaints. They are an excellent product in every respect.
Important note
Many customers have asked us what size they should bore their block at to allow for a proper piston to wall clearance. The required clearance is built into the piston already. For example if these pistons show a given size such as 4.030 then that is exactly what you will bore the block to. The actual size of the pistons when measured at the skirt, 1/2 inch above the tang will show to be approx. 4.026. The needed clearance is built in. Should you be using these pistons in a marine app. where the boat receives it's water from the lake, then an additional 1.5-2.0 thous. would be added to your final bore size, and some forced induction apps may also require a slight increase in bore size.
Compression Ratio Chart.
The calculations below assume your pistons are at zero deck. Let's say your compression calculates out to be 10.50 for example based on having the pistons at zero deck (flush with the deck), but your pistons were going to be .005 in the hole, then the comp. ratio would only drop to 10.40, and if left .010 in the hole, then it would drop to approx. 10.30 We do recommend having your block decked to allow the piston to set anywhere from flush (zero) to .005 in the hole for optimal performance.
Piston Family |
Cylinder Head Volume |
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106.0cc |
117.0cc |
119.0cc |
121.0cc |
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496 |
Static Compression Ratio |
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4.280 Bore |
11.36 |
10.30 |
10.13 |
9.97 |
4.310 Bore |
11.51 |
10.43 |
10.26 |
10.10 |
4.320 Bore |
11.56 |
10.48 |
10.31 |
10.14 |
4.350 Bore |
11.70 |
10.61 |
10.43 |
10.27 |
Our custom made Wiseco pistons have a compression height that is .010 taller than nearly all catalog pistons on the market. We find this to be a very valuable feature. Since our pistons sit at a taller than normal compression height, you will only have to remove approx. .005-.010 off the deck surface of a virgin block to achieve a zero deck. This also allows for future deck re-surfacing and still not ending too far below stock deck height.
Leaving the deck on your block thick makes for a stronger block that resists flexing and also runs cooler, as the deck thickness has a lot to do with the dissipation of heat. Blocks with decks cut down to any great amount are also prone to cracking. This is why our pistons are designed to sit flush, (zero deck) at .010 below stock deck height.
Since nearly all bbc catalog pistons on the market sit .020 below the surface of a virgin block, the only way to achieve a zero deck using such pistons would be to cut .020 off the deck surface. This compromises the integrity of the block, in our opinion. Should you decide to leave the block deck higher up, using such pistons creates a new issue of having a very poor quench/squish zone. The only way you could really take advantage of a catalog piston is by having a block that needs to or has already been butchered down to 9.780 deck height. Having the piston sitting flush with the deck is very desirable, regardless of the fact that your overall compression ratio is slightly higher than if it were sitting below the deck.
We have found that 95% of our customers are using a virgin block or a block that is close to stock deck height. This is why we have designed our pistons to have a taller compression height. On very rare occasions, you may end up with a block that has the piston out of the hole by a few thousandths and this not a problem at all. Most head gaskets are approx. .040 thick, and should you end up with a quench zone of .035, then that is ok. If the quench zone ends up below .035, then there are plenty of .050 thick head gaskets on the market. One more benefit to this is that most machine shops charge much more to deck a block down from stock deck height to 9.780 than they would to do a light cleanup, and that's all that's needed when using our Wiseco pistons.
Another good feature about our pistons having a taller compression height is that the ring land above the top ring is much stronger by being .010 thicker. When pistons encounter the effects of detonation, it is not uncommon to see pistons with the ring land above the top ring broken off. The thicker ring land also makes a better heat sink.
You may have noticed that our Wiseco custom made forged pistons are referred to as Racing Pistons on the package. This does not mean that the pistons are for racing only. This is a generic term, referring to their ability to be used in high performance applications as well as for street rod use. These pistons are perfectly designed for use on the street, as well as for medium to upper level drag racing.
Our custom made Wiseco forged pistons are made from 2618 aircraft alloy. We find this alloy to be much more suitable for high performance engines than the common 4032 forged alloy. You will usually see the higher end pistons on the market using 2618 aircraft alloy.
Why go with 2618 forged pistons? If you encounter certain tuning issues, detonation is highly probable, and its effects can cause severe damage to your engine. The 2618 forged piston is able to withstand the damaging effects from detonation to a higher degree than the lower cost 4032 forged pistons, especially non-forged hypereutectic pistons such as Speed Pro or Keith Black, and many others.
Our Wiseco forged pistons will clear most any valve size on the market with ease even with the use of large lift cams.
Item Code |
KP441A7 |
Vendor Name |
Wiseco |
Product Type |
Race Series for street/strip use |
Product Model |
Custom built for SWP |
Engine Displacement (cu.in.) |
496 |
Engine Family |
CHEVROLET - Big Block V8 |
Material |
2618 Aircraft Alloy, Forged |
Base Bore (in) |
4.250+.070=4.320 |
Stroke (in) |
4.250 |
Rod Length (in) |
6.385 |
Compression Height (in) |
1.280 |
Top Type |
Dome top |
Net Head Volume (cc) |
+20cc |
Deck Thickness (in) |
0.350 |
Weight Without Pin (g) |
595 APPROX. |
Wrist Pin Diameter (in) |
STD |
Wrist Pin Weight (g) |
157 |
Pin Lock Type |
Spiral |
Ring Set # |
683-30 |
Top Ring Groove Size |
5/64 in. |
Second Ring Groove Size |
5/64 in. |
Oil Ring Groove Size |
3/16 in. |
WISECO FULLY FORGED PISTONS RATED AT 700+ HP. THIS SALE IS FOR A FULL SET OF PISTONS. WISECO PISTONS ARE 100% MANUFACTURED IN THE USA. THEY ARE ONE OF THE HIGHEST RATED PISTONS IN THE COUNTRY.
These pistons are for use with full floating bushed rods, or press fit . RING GROOVE SIZE, 5/64 5/64 3/16. SEE FULL PISTON SPECS ABOVE.
We offer these pistons in flat or dome style, and most bore sizes. See our other listings.
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Attention Valued Customers!
When it comes to highly technical questions, our sales team at Skip White Performance might not always have the detailed answers you're looking for, especially on topics like installation procedures or tuning.
For those with detailed or specific questions, we strongly recommend checking out automotive forums and communities where these products are frequently discussed. These forums are a treasure trove of information and can provide the expert advice you need. Additionally, YouTube has countless tutorials and guides that walk you through the installation process and other technical details.
Please note: While we're here to provide top-notch products, we cannot be held responsible for any damage resulting from the use or installation of this product. Make sure to do your research and proceed with caution!
Thank you for choosing Skip White Performance!
Disclaimer
Skip White Performance is not liable for any collateral damage or incidental issues arising from the use or misuse of our products. High-performance parts are intended for experienced professionals and enthusiasts. Use at your own risk.Product Information
UPC | 334833684641 |
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Product Type | Shipped Product |
Shipping Cost | 24.0 |
Number of reviews | 0 |
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