Sorensen Performance
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Dynotesting      Enginebuildups      Automotive

Frequently Asked Questions

Q. Will these heads bolt onto my stock Motor?
A. Yes, with the use of stock low dome pistons. With proper engine building you can shorten the barrels to effectively give you a .035 squish band giving you maximum results with a compression increase of .5 to 1 point depending upon the engine configuration.

Q. Why are these heads so much better?
A. Because these heads have a unique peanut shaped combustion chamber and dual 30 degree squish bands that promote excellent turbulence and, a complete burn of the air/gas mixture. This allows cranking compression of around 210Psi on pump gas with proper tuning.

Q. Why doesn’t the competition flow test their heads?
A. Simple, because when we spoke to them about it we were told they felt it was a waste of time and because they were only shovelheads (“who cares?”). Also, when we tested some of the competitions’ castings they fell very short of their advertised claims, coming up as low as 245 cfm @ 28 in. on the heads we tested.

Q. What is the difference between 3/8” valves and thin stem valves?
A. We use thin stem valves which are the same diameter as the Evo/Twin cams for lighter weight and better flow. We also use a tapered guide for better flow as well. The 3/8” valves are big and heavy which impedes flow and adds unneeded weight in the valve train.

Q. Can I bolt on a stock intake and expect maximum results?
A. No! By nature the shovel intakes do not flow well. Both the SuperE intake and the SuperG intake need port work. The SuperE intake responds OK with porting and will  flow of up to around 240cfm before going turbulant. The SuperG intake requires an extensive amount of work to achieve real airflow. This work will require welding, epoxying, porting and extensive flow bench work to achieve. We have done the work for you, SpChoppers offers a billet SuperG intake that has over 100hours of flow bench invested into it. The manifolds are CNC machined and replicate all the hard work involved. They work great on a modified stock shovel as well.

Q. Why should I consider using S&S or SP Chopper Evo conversion blocks?
A. The geometry of the shovelhead is quite poor. However, by using the conversion blocks, you can use updated Evo lifters and more aggressive profiled cams. What this does, is allow you to make more power down low and up high with a smaller cam. Please see our attached dyno sheets. Our blocks are computer designed and mocked up in solid works and the lifter bore angles have been corrected to be the best they possibly can be. Our parts are machined in small runs and held to extremely tight tolerances and are truly the best on the market.

Q. Do the competitors' heads you mentioned really run hot and why are the SP heads a better choice?
A. Yes they do. When heads are made into a bathtub style chamber, they retain too much material, and as a result, it causes overheating of the heads and as mentioned in our brochure can result in the inserts becoming loose and falling out. Our SP heads are designed with a unique peanut shaped chamber with just enough material in the critical spots, to get things moving. We also added the much needed fin area on the top of the head, to pull heat out of the center and thereby reduce overheating. In addition, we also increased the size of the fin area on the entire head to further reduce overheating.

 Q. How much power can I really make with these heads?
A. There is enough room to install a 2.100 valve on a 93” motor and, with proper building techniques and the proper selection of parts, a person could easily achieve 120 hp plus using proper fuel. And, as we have shown, it’s really quite simple to build an engine capable of 108 hp on straight 92 octane pump gas.

Q. I don’t have the tools to build an engine like this. Do you custom build?
A. Not outside of Canada generally.

Q. I have been told that HP numbers will vary from place to place. Is this true?
A. Yes! Altitudes, temperatures, the tuner, dyno operator, type of oil, engine temperature are all factors that need to be taken into consideration. Our engines have been tested on other dynos and only varied from 0 to 3 hp, all depending on the factors taken into consideration.

Q. What type of carburetor works best?
A. We have dyno tested numerous carburetors and we have found that the essentially what the motor sees is total airflow. There are minor gains to be had brand to brand. On smaller engines a big bored CV is hard to beat, it gives great response with no restriction on Wot power.  Your basic G carb with a thunderjet is pretty hard to beat for simplicity and ease of tuning. A 40mm carb will become a restriction at roughly 84hp.

Q. Are there any type of warranty on bottom ends or complete engines?

A. Baseline engines or bottom ends have 5000mile or 6month warranty. 142" All out highperf engines do not come with a warranty. Any Disassembly of Engines or Lower assemblies or Modifications without prior authorization will effectively terminate and make all warranties null and void. 

Q.Can I return special custom ordered parts?

A.We do not return custom ordered parts. That is why they are custom to your specifications. Please make you get your order right the first time =o).

Q. Can I order a set of heads and get them in a couple weeks?

A. Unfortuneatly no. To preserve the utmost highest quality of my products I have moved all machining and heat treating in house and do everything myself. As I have many orders to fill, it may take a bit of time for me to machine and complete your products ordered, be rest assured that as much care and time is taken in each order to provide you with the best product possible. Do remember these are CNC machined parts and take a very large required runtime and handwork to prouduce each product.

Q. Can I use my stock HD bolts or a aftermarket bolt such as S&S with the Harley thread pitch

A. NO NO NO NO ! The heads are 7/16x14 coarse thread pitch. Any such attempt will damage the threads Immediately!  We do not use fine thread bolts or fine thread inserts because the thread engagement is so minimal they pull out.

Q. I notice that the bolt holes for the rocker boxes are not threaded to the bottom is there a reason for this?

A. Yes , they are purposely not threaded to the bottom to allow for wear and tear over the years and over torqueing , that if the threads do get damaged over time instead of immediately having to helicoil the hole you can run a roll tap down and voila now you have more threads and just replace your bolts with a longer bolt an easy repair at home and your back on the road. If you feel you want a bit more thread you can easily just thread in a roll tap quickly and add a few more threads.

Q. Can I tq the heads to stock 65lbs tq spec ?

A. NO NO NO NO ! Do not tq the heads anymore than 40ftlbs! You will pull the threads out of the head.

Q. The threads looks different than normal threads, are they double tapped or wrong?

A. The heads are tapped using a Roll Tap/Form tap that molds the aluminum into a shape and they have a different look to them and you can actually see the center of the thread looks like a gap at the aluminum is rolled together into a shape.  A cutting tap cuts the aluminum and has a different look and a weaker thread.

Q.  Should I lube the bolt?

A. I like to use antiseize on the bolt to prevent galling of the threads, also its a smart idea to thread the bolts your going to use in first, some bolts may possibly need a die run down them quick to chase the threads.

Any modifications , repairs etc void all warranty unless prior approval is agreed upon by Sorensen Performance.

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