Welcome to Inertia Motorsports, where you can get #inertiapowered ! 

Home of the Spartan and the SRT MAX Plus camshafts, record breaking Hemi builds and much more! We have built more than 450 HEMI strokers from oilpan to intake over the last 10+ years. Nobody else in the business has as much experience as we do with this motor platform.

Our goal is to provide the Mopar community with top of the line parts with the best customer service in the industry.

We are here to serve you, so please give us a call or send us an email (or contact us via Facebook, Instagram or Twitter) and we are more than happy to help with anything we can.

Inertia cams - why do they cost more?

 

One question I’ve been asked from potential customers is why our cams are more expensive than some offerings from some of the big cam competition. That’s a good question. Besides the obvious tech support when you have questions on the cam install the primary reasons are:   

 

Originally when we started doing Hemi cams we were buying cores from the same core vendors that supply all the bigger cam grinders. There are only a few companies that supply cam cores for Hemi engines and they are cost reduced quite a bit as far as the materials and process of manufacturer which lead to the following problems:  One of the cam core vendors had many cams heat treated too hard and the lobes would develop cracks from being so hard they were brittle. Another manufacturer was on the soft side and over time the lifters would eat into the bores and cause it to fail. Additionally, about every six months this vendor would miss the dimension of the “hat” section on the front of the cam that creates the space for the tensioner plate to ride between the cam and sprocket and cause the cam and sprocket to act like a brake caliper with the tensioner being the disk. This would lock up the cam and cause the sprocket to friction weld to the tensioner resulting in the sprocket spinning and shearing the locating pin on the cam and bending some valves. Then virtually all the cores were being roughed in so far that most of the time you couldn’t get the grind in on the cam without either changing the installation centerline causing that to be excessively retarded or grinding the cam on a smaller base circle which will make excessive valve noise, unless longer custom pushrods are used. I’m sure many of you have had that problem.

 

We struggled with these issues till about 5-6 years ago when we went to a more expensive custom core that is made with much better 8620 chrome molly but is also copper plated. This way the cam can be heat treated in an oven where there is better process control.  In the oven the bare ground surfaces (lobes and journals) get heat treated in the oven so they are hard and don’t wear and then the plated areas remain softer and don’t harden because the copper disperses the heat too fast for them to harden.  The down side is billet machined copper plated 8620 cores are much more expensive.  Those of you who have purchased cams from us probably noticed the copper plating between the lobes.  Most if not all of the other cores are heat treated with induction coils that heat each lobe individually over the period of a few seconds and then move to the next lobe. This process works with cheaper non copper plated material and cost less but the consistency of the hardening is not as accurate and therefore there are more problems with the consistency of the heat treating and you have lobes being too hard and breaking or too soft and the lifters eating into the lobes. 

 

Since the cores are also custom made we have them only semi-roughed in so we don’t risk having to reduce base circle in order to get the grind we desire in and therefore don’t need to go to custom pushrods for this reason. It does take more time to grind and wears on the grinding wheel more but we can get a greater variety of lobes in this way and not have to shrink the base circle or retard the cam. Next, nearly all the cams we do are ground as custom orders so if you want to change ramp or follower rate or LSA that is not a problem. For example many of the 5.7 people want the sound of the SRT Max Plus but if you put the Max Plus in a 5.7 it has less bottom end performance and really needs a higher stall converter and gears to get off the line well.  The Spartan Plus has good bottom end torque so it works well on a stock converter in a 5.7 but it doesn’t have as much overlap when ground on a 112 LSA so it doesn’t have as much lope and many people want that choppy cam lope. So to keep the strong bottom end torque and get comparable lope to a SRT Max we can change the Spartan plus to a 110 LSA  and you can have good bottom end TQ and big cam lope.  This is becoming a common request.  

 

Another example is the SRT Max Plus is a great cam for a 6.1 and in the bigger 6.1 engine it has good power throughout the rpm range and in a 6.1 so you don’t need a converter on the street. It also has decent lope but a big benefit that most people don’t know is the ramp rates are very similar to the stock cam. This, combined with the lift of under 0.570 means valve train life and reliability will be very close to stock and since the 6.1 heads don’t flow more than a couple cfm higher between 0.550 and 0.650 lift there is little if any power gain to be had by pushing the ramp rate higher to get big lift numbers on hemi heads. More lift merely requires you spend more money on aftermarket springs which are almost all less reliable and break more often than the stock 6.1, 5.7 eagle or 6.4 springs. Additionally, the extra lift doesn’t work well with the stock rockers and scuffs the rocker pads and valve tips and the stock valve seals tend to work better too.  Then of course with more lift there’s more stress on the already failure prone lifters and timing tensioner, but for the 1% people who track their car more than street drive it or don’t need a stock reliability cam because it’s driven so infrequently, we can do very similar duration to the Max Plus but with lobes having more aggressive rates that have more area under the curve yet still keep the lift at 0.560” so it’s not putting extra stress on where it’s not going to help because it would be lifting the valves past where the ports in the heads increase flow. This higher rate version of the Max Plus makes about 10 more HP and TQ throughout the rpm range than the Max Plus but the higher rates will wear the valve train and stress parts more than stock. So, I wouldn’t call this a 100K plus mile cam as it would need springs, lifters, and heads rebuilt more often.  We call this one the SRT Max Plus P, so it’s a tradeoff as any cam that has higher than usual lift for a given duration is getting the lift at the expense of more load on the valve train.  That’s almost always the case.

 

And yes, if you do want more lift we have lobes that will do that you just have to call up and ask. (512-964-7724). Although, you may have to listen to me tell you the extra lift won’t help very much if any and is less reliable.  

 

I hope this and actual technical customer service explains why Inertia cams may cost a bit more than some of the competition. If everything above is a bit beyond your cam acumen or I just got too wordy and you didn’t bother reading it, the short answer is They Cost more because they are worth it!

Why run Inertia CNC ported heads? What sets us apart?

Over the years while speaking with customers I’ve discovered that there is a lot of confusion about ported heads.  For example, many of the people who inquire about heads ask about ported and polished heads.  In general, “polishing” is a term from the 50’s and 60’s where they would polish the runners to make them smoother with the idea of increasing air flow. In reality this isn’t the case. Due to boundary layer effects, a smooth surface doesn’t actually flow more air than a rough “as cast” surface and in a wet flow application, the smooth surface can actually allow fuel to puddle and fall out of suspension.   Therefore, polishing is often just a way to justify charging more money because it looks as if more work has been done because it’s shiny and cool looking. In most cases a shiny port doesn’t hurt anything unless it’s wet flow like an intake port or wet flow intake manifold in which case fuel can puddle causing fuel distribution problems. Due to shearing, a rough surface can help keep the fuel in suspension better.

Another misconception is the flow bench. I used to be guilty of this one when I pretty much assumed that the more air a port could flow on a bench the more potential for power it had. While it’s true that flow numbers are a decent tuning tool, they aren’t as significant as most people (including many porters and engine builders believe). There are things you can do to a port that will substantially increase flow numbers and will kill power and there are things you can do that kill flow bench numbers and will pick power up. Flow bench numbers in a static valve condition are just a minor tuning aid for cylinder head development. That, and many shops are going to advertise the biggest numbers regardless of what they actually see. A good example of this is our stock valve 6.1 head made 368 CFM on a bench and a competitor’s head was being advertised at 355 cfm. A month later the same competitor was advertising 372 cfm. The real give away here was there head now made a bigger airflow gains from 0.550” lift to 0.600 where the 372 rating came than it did from 0.500” to 0.550” lift and that is extremely unlikely to happen, to put it kindly. Furthermore, flow benches are similar to dynos in that you can see quite varied results from one to the next. Our heads that made 368 on a dyno in Houston only made 345 on our porter Phil’s bench.

Making power in heads is primarily about shape and size and it takes a lot of knowledge and experience to find out what those shapes are and what the correct size is for a given application. The new Hemi already has a pretty good port and valve job so it’s not like the good old days where almost anything you did to increase the size of a small block head would pick up power and most machine shops and porting services could get some decent results. To make decent power gains on a new Hemi you have to know what you’re doing. In this case to get our heads done I went to one of the top race head shops in the business that does top level work at the highest levels of racing. Inertia’s heads are done exclusively by Phil Coleman who owns Finish First Racing Heads. I hooked up with Phil about 13 years ago because I found out he was doing many of the W8, W9 and P5 NASCAR heads on the Dodge Cup cars and Trucks.   It turned out he was doing a lot of NHRA Pro Stock work also,as at that point his heads were on over 200 NASCAR Cup car event wins and 4 National Championship Cars, as well over 200 Pro Stock wins and 4 Pro Stock Championships. Recently I found out that the 68 Hemi super stock car that won last year’s superstock Hemi shootout was running his heads. So Phil knows Hemi. Not many if any other head porters have that kind of resume.

What this translates to for our Hemi heads is we get about as much out of our heads as the casting allows. Furthermore, with the work being done by a “Cup Shop” it’s being done on equipment the typical race head shop doesn’t have. For example our valve jobs are performed on an $80,000 Newen EPOC single point CNC valve job machine that allows the valve job to be laid out on a computer screen and then duplicated by theCNC cutter It can do things you simply can’t do with pre shaped cutters that only offer ½” in order to fit the entire valve job. That’s why most of the better shops doing porting on Hemi heads use a 5 angle valve job on the intake side. The Newen allows for a 6 angle job that blended into the port better. Then the exhaust side is a radius job since you don’t need the edges of the seat for fuel shear on the exhaust side.

This level of shop also has the capacity of normally being able to turn a set of heads around in a week or sometimes less if we don’t already have them finished and bagged on the shelf. That’s because they have 3 Haas CNC machines to do the work very efficiently.    

In the end a CNC machine can only duplicate what the head porter has done and that’s where having a porter with the experience and ability to get the most out of a particular casting come in to play.

If you’re considering a set of heads for your 5.7, 6.1, 5.7 VVT, 6.4 or 6.2 HEMI, keep us in mind and give us a call for a chat about your needs and wants for your vehicle.

- Stu Hansen

Inertia Motorsports

 

Thank you for visiting and we look forward to helping you make your car or truck the best it can be.

Email us: info@inertiamotorsports.com

Phone:

512-964-7724

510-277-4214

Service & Sales:

392stu@inertiamotorsports.com

jarz@inertiamotorsports.com 



 

     
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