So…. What makes our cylinder heads so much different than the rest???? Below I will break down many facets of our cylinder head program that puts our head program in a totally different classification than any other.
1- Direct benefits of in house testing to offer back to back comparatives concerning the effects of material and procedural alterations.
This basically means that we make changes, note the differences and apply the results to each engine or cylinder head profile. When testing a component the test is only as good as what data is collected and how it is factored into the overall product. Few companies test components, a fewer amount do anything with the data other than just forget it!
Here we have been known to assemble complete engines simply to use as a basis for direct comparison of similar cylinder head offerings!
Direct Benefits of using our components in our Racing Applications-
The exact same components that are used in ALL of our cylinder head offerings are also used in the Aircooled Innovations Racing Porsche 914-4 race engine. This includes valves, valve springs, valve seats and all other major components! We have been known to run 23 consecutive races (two seasons of SCCA competition) with these same components without a single failure. Keep in mind that this engine spins as much as 8,500 RPM for 30 solid minutes. What does this mean to you?? Well even if you want a low compression, low-speed engine for your Bus or a high CR Performer engine you can know that the components that are used to comprise your cylinder heads are completely overkill engineered.
2- Material and hardware selection
This is BY FAR the biggest benefit to our cylinder head program. All the testing and the vast amount of engines we have built has given us direct feedback on not only our theory and procedures but also what wear and tear and street and race abuse and neglect can do to the materials that comprise the cylinder head package. Below I will break down most of the materials and components we use and why we use them.
Head Castings- The head casting is the foundation in which all other valve related components reside. The head not only sees the most heat of the entire engine but it also has the biggest role in determining the reliability and especially longevity.
We use BRAND NEW cylinder head castings to base our heads from. This separates our head program from most others simply because other companies would rather dig up a 30-year-old head and clean it up rather than just accepting the fact that it’s just plain worn out and has been heated cycled (and generally overheated) for its entire life!
Replacing the 30-year-old heads with new components is just plain smart and that’s why we do it as a standard. Trying to build an engine that’s based on a 30-year-old head would be equal to painting up an old house that’s full of Termites and rotting down- it’ll work, but not very well and not for very long!!
Starting fresh gives the engine the best chance of living past that 100,000-mile longevity goal without needing attention and without carrying spare tools in the trunk!
3-Valve Seats- Absolutely, without a doubt valve seats are the hottest topic concerning the Type 4 cylinder head! The valve seats that were installed in the stock heads featured 1970s technology for material composition and also the procedures for their install were not as refined as we have today.
Most of the specifications about material and installation of our valve seats are proprietary to our cylinder head program and cannot be shared here. I can, however, tell you that the valve seats that come in the AMC new castings are removed and thrown away, in favor of our own seats installed our own way.
To our knowledge, we have not had a set of heads, or a customer’s engine “drop a valve seat” since 1997! Many things impact valve seat failures, heat being the most prominent, yet even with engines that have been severely overheated these seats still have not failed! I have purposely overheated engines to the sum of 550-degree head temps only to find the seats have not moved!
4-Valves- The valves we use are modern stainless steel units that are made primarily for us by SI industries. These valves far supersede the composition of older stainless steel valves and they offer extreme reliability and feature resilience to wear, even when not adjusted timely and even when downright abused!
These stainless valves can take extreme conditions of heat and RPM between valve adjustments, they have very minimal stretch and this allows for increased intervals of valve adjustments for typical engines. All of my personal engines feature these valves and as of this writing, one of these vehicles has 3.7 years on its valve adjustment without being touched, with over 60,000 miles racked up during that time!
We do feel that these valves are far superior to the “Sodium Filled” valves that were OEM equipment on some Type 4 engines- none of our heads are available with these sodium filled valves that can fail and leave you with an engine that’s just a pile of rubble!
Even our lowest performance offerings right up to some full race, 8,500 RPM beasts feature stainless steel valves and the stock valves that come new in the heads when we receive them new, are removed and trashed as they are substandard.
Our most extreme cylinder head offerings, the LE 220, LE 230 and our Billet “Ultra” heads come with proprietary valve options that open up new doors for RPM levels.
Valve guides- Valve guides are an often overlooked item for quality because most people really don’t know the differences from one guide to the next- I have even been guilty of this generic way of thought!
The fact is that valve guides are THE BIGGEST wear item associated with the cylinder head! This is mainly because they are made of softer material than the valves they are supporting and sometimes with improper valve train geometry their wear is accelerated. With worn valve guides, valve jobs are short lived and oil consumption and crankcase pressure is also elevated, both of which impede performance and tuning.
The valve guides used in all our heads are resilient to wear and are made of a harder material than the stock guides. Stock guides are removed from all of our heads and replaced with our proprietary guides as standard procedure.
5-Valve springs- STOCK VALVE SPRINGS ARE ONLY COMPATIBLE WITH 100% stock cams! That’s right, and since we do not promote the use of stock cams (even for 100% stock engines) all of our heads come with “Heavy Duty” valve springs. Some heads feature dual valve springs, but most of the most popular offerings provide plenty of valve control for the port work they feature and unless severely over revved would not have an issue of valve control with just a single spring. Keeping a single spring increases the fully seated and fully open pressure just enough without producing wear from “over springing” the valves. This keeps cams and lifters especially “Happy”.
Stock valve springs are easily overworked and I have broken them on even low RPM engines with only .030 more valve lift than stock. For this reason, I NEVER promote the use of the stock valve springs, better springs are one of the cheapest and wisest upgrades that one can do to the cylinder heads.
6-“Better” springs- are a standard in all the heads you will see mentioned here.
Retainers-It’s the job of the “retainer” to do just that, Retain! These very simple but very important parts play a big role in valve control and engine failures.
The stock Type 4 retainers are “stamped steel” and when being used with any camshaft other than a 100% stock grind or when operating above 5,000 RPM (even with a stock cam) the stock retainers are being asked to do way more than they are designed to do!
Retainer failures generally allow the engine to “swallow a valve” as the valve keepers are generally pushed through the center of the valve retainer allowing the valve to simply slide right through the retainer and into its meeting place with the piston, in the combustion chamber. This immediately creates a catastrophic failure and wastes the engine.
The retainers we use as standard equipment are Chromoly steel and offer much more material strength than the stock, stamped steel units. The stronger material resists the forces that spread the retainer and allows the keepers to push through. These retainers help to create a very good sense of security within the valve train and I can honestly say that I have never seen one of these chromoly units fail!
When RPM demands lighter and stronger components we offer Titanium retainers as well.