I am going the modified head route that I am discussing in another thread. During research that I did I came across allot of interesting information on the camshaft that has a very large impact on the head itself.

As with anything involved with modifying an engine, there are going to be pros and cons as well as those that agree and disagree. First, lets review some Cam Basics 101 with the following video:


Now for a little more detail on a camshaft technical information with this video.


I mentioned another thread above and in that thread I talk with Mike Schutlz that is ThumperHeads. Mike is a not only a machinist but also a long time Muscle Car guy that still owns the the 67 Mustang that he bought brand new. Mike's knowledge on all things engines is amazing and I have started calling him "Doctor" in our conversations. I have a RMW Dominator Cam and love it. My SOTP dyno told me I was reving faster after I installed it and I love what I call the guttural sound of the engine at low rpms.

I have lots of emails from Mike and will be posting more of our discussions over the days to come. Here is just a small snippet and you will see that he is using many of the technical terms mentioned in the second video above: Mike Schultz - Depending on application, in this case a larger V8, the correct camshaft can gain over 100 HP when coupled to the right cylinder head numbers. The numbers on the MINI will be smaller but increases are still there. The big thing with cams are the Centerline that for Blower/Turbo engines you will see around 110-113, and, Lobe Separation Angels at a 110-114 , even a few 116-117 angles out there.

Next post - The MINI stock cam and some options. Will be addressing tunes and camshaft gears as well.

 

The OEM Cam

Many times you will see a cam expressed in numbers presented as xxx/xxx for a single overhead cam engine, SOHC, as we have in our Gen1 MINIs. In this instance the first number is the intake value and the second is the exhaust value. This can become somewhat difficult as some manufactures will either include or exclude the "rocker arm ratio" in their lift numbers. The rocker arm is like a teeter totter/seesaw whereas the distance from the center pivot point increases or decreases the travel distance. This is similar to a lever and fulcrum. For the Gen1 the Intake Rocker Arm Ratio ,RR, is 1.64 and 1.44 for the Exhaust. The "lobe lift" value of the cam would be multiplied by the RR to obtain the total "lift".

Cam Intake Lobe Lift aaa0.203"
Intake RR aaaaaaaaaaa x 1.64
Valve Lift aaaaaaaaaaaa0. 333"

Cam Exhaust Lobe Lift aaa0.222"
Exhaust RR aaaaaaaaaaa x 1.44
Valve Lift aaaaaaaaaaaaaa0.320"

In other words you may see a R53 Cam expressed as either .203/222 (without the RR factored in) or .333/.320 (with RR).

Next it appears the Intake Duration for the Stock Cam is 244 with the Exhaust at 255. With the information of the second video above and now with both the valve lift and cam duration know there should be a better understanding on the Newman Cam Chart below. This chart can be seen here and then go to the second page.



Newman has six different cams for the Gen1. A review will reflect that Newman says where the Power Band should be, the "Duration" for both Int/Exh, the Valve lift which is the cam lobe lift increased by the RR, the cam lift which is only the lobe lift, along with some Timing and Full Lift values. Base upon the Stock Cam durations, the PH1/2 is the closest to the Stock Cam relative to duration but a closer look reveals that all the Newman Lobe Lifts are anywhere from 20% to almost 42% on the intake side.

Next post will be where I asked Mike Schultz some specific questions.

 

And if you have questions, please post them.

I can tell you from researching all this stuff that there is "marketing languageese" involved in many instances.

 

Hardcore Motorhead Thoughts

I have mentioned Mike Schultz aka ThumperHeads in this thread as well as another thread I have going here on NAM. Today will post some of his answers/thoughts to some of my questions. Let’s say I asked “just a few” questions and I really appreciate that Mike took the time to try to humor this motorhead neophyte.

So you still have the 1967 Mustang you bought new, what was the first cam you installed?

My first was a Crower and it was a dog. I didn’t have allot of money back then and asked a few gearheads what to do. My friend, Larry Holt, at a local San Diego speed shop told me to loosen the rocker arms and pull some of the lift off the camshaft. Easy fix for free.

What is a good cam?

Ha, with that question the guy selling the cam should ask a question, like how are you planning to drive your car? Take a look at the Newman Cam Page and what is about the first thing you see? It’s the Power Band range!!! Determination by driving style! Street 2500-6500 rpm. Then are you planning any future mods? What injectors you have? How much money you want to spend?

Working with F/I engines and Positive air boosted engines , it is found that if we open the valves sooner, the engine will use it and start pulling power faster. Top End will remain very close to the same HP@ rpm. and now we have more lower torque and HP.

So which camshaft ? In the US V8 world, and the Ricer community, there have been years and years of testing and racing. Go to the Comp Cam catalog and see all the cams and types for just the FORD 289-303-5.0 engines. Also when you ask someone, there is usually someone to help get you close with the power levels you want. There are just a few distributors/manufacturers for MINI camshafts out there and even fewer with knowledge on if you really need a tune.

NUMBERS Play a big part in Cam Choice!! Carroll Shelby said back in the 70's "when you find the perfect camshaft for you application, go one size SMALLER !" This applies even today. Many selling cams point to a .400” lift but the actual lift might be .352. Camshafts made in the USA have a SAE Measure value stamped on them.

 

Before getting back to Mike aka ThumperHeads, going to do a brief review of some very important stuff and if you are not a gear/motorhead this stuff is not the easiest stuff to digest.

1.) A basic cam "section cut" is below. Lobe Center Line and Lift are some important items to understand. If the Base Circle dimension is added to the Lift then calculations can be made to determine if there is interference with other head elements. For our Gen1 MINIs, with the OEM Base Circle and a Lift of approximately 0.396" the spark plug tube will come into the equation. I have a RMW Dominator Cam with an advertised 0.400" lift and there was contact with my plug tubes. The interference was very slight but I chose to ding the tube. I ground down a socket so that I could remove/replace my plugs.

I have seen a post here on NAM where a RMW Dominator cam was installed and the contact was so great that the lobe wore a hole in the tube that then allowed engine oil to seep out. The amount of my interference did not appear as great as the unfortunate member with the tube hole but this is most likely because of the manufacture tolerances involved for the head. The head is a "cast" production whereas the cam is "machined," two vastly different procedures. This cast vs. machined element comes into play with CNC head machining as although the CNC process can achieve tolerances of 0.0001 tolerances, the work is performed on a "cast" head where the varying distance between cast ports are rarely considered during the CNC process. In a thread I have going on Heads, there is an article where a well known machine shop owner has stated that he will see CNC ported heads where there is a noticeable difference in the porting due to this casting tolerance impact. SO REMEMBER to always check the interference at your plug tube when installed a Cam.



2.) Now we have a drawing that reflects the Lobe Separation angle, another very important item on cams. In a post above I noted that Mike at ThumperHeads said that most blower (supercharged)/turbo engines have Lobe Separation values of 110 to 114 and sometimes as much as 117. One of the most important aspects of the Lobe Separation is the duration in time when the intake valve starts to open compared to the exhaust valve. A Lobe Separation value of zero would mean that the intake valve is opening at the same time as the exhaust.

So, what are the engine aspects of a "tight" or smaller Lobe Separation value versus a "wide" or larger value?

Tight/Smaller value - Most of what you read is that if 117 is a high side value for separation than 102 is considered low. 102 = tight, 117 = wide. a.) A tight value will provide a rougher idle as the intake vacuum is decreased. If you have ever heard a drag car, that is typical of tight lobe separation, b.) Higher head compression will result with this type of separation. Increase head compression can impact the Exhaust Gas Temperature (EGT) but this can be addressed in the spark timing, c.) Valve "overlap" will increase. Overlap is where the intake and exhaust valves are open at the same time. Overlap has greater impact on the engine function based on the relationship of the beginning of the overlap relative to Top Dead Center, TDC. Top dead center is when the piston is at the top of it's stroke. If the overlap occurs to early in the stroke - prior to TDC, exhaust gases can push back through the intake valve. Later in the stroke - after TDC then the opposite can occur where the intake air is pushed out the exhaust valve, d.) A tighter value will increase the amount of maximum torque that the engine can produce, e,) The Torque Curve will start lower in the RPM range.

Wide/Higher Value - here the value is more toward 117 with the following results: a.) Smoother engine idle as the vacuum pressure increases, b.) Lower engine compression as less air is able to enter, c.) Decreased valve overlap, d.) A wider value will decrease the amount of maximum torque that the engine can produce, e.) The Torque Curve will start higher in the RPM Range.



A tight Lobe Separation value example

 

I am boxing up a head to be sent to ThumperHeads and as I have the old OEM Cam I took a couple of pictures to show what type of clearance there is between the lobe and the spark plug tube.





The gap is about 0.050".

Pictures do not really reflect how small the MINI engine is. I am just amazed that quarter size intake valves, with dime size exhaust valves along with ports smaller than a Halloween type candy bar is able to put out the horsepower that it does. More amazing is that that there are smaller engines that produce even more power.

 

And it is the exhaust lobe that is the issue, the intakes are not involved.

 

Hardcore Motorhead Thoughts - Part 2

More questions from me and answers from Mike Schultz aka ThumperHeads

Allot of times you will see that those selling a cam put a name on it. The "Dominator" I have is the perfect example. What were some of the cams you know about?

Putting a name on a car or an engine part has and always will be a part of marketing. In the 1950's there was the Duntov 30/30, in the early 1960's there was the 1/2 race, 3/4 race and Full Race. Then later in the 60's the Le Mans cam came out. Just like today, most have no idea what the cam did but the name was catchy so people buy it. The Duntov 30/30 had a "lash" of 0.30". The lash is the measurement from the tip of valve to the tip of the rocker arm. Those 1/2, 3/4 and Full Race cams, had to do with the length of the race track, 1/2 mile, 3/4 mile and 1 mile. The Le Mans, well thank Shelby for that one. It was his small block, solid lifter cam.

For a Motorhead, what is the basic purpose of changing the way a cam is made?

Old Gear heads have been finding 'tricks of the trade' since there WAS a trade. We know the sooner we can get that intake open, the sooner the air goes in, and the more power is made. A tighter LSA, Lobe Separation Angle, does just that. The tigher the LSA, the sooner the lobe gets to the valve.

You mentioned that you were developing your own cams, can you tell me a little about that?

The Mini market is pretty small and I could not find anybody here in the US to grind the cams so I went across the Pond. I have spent a lot of time talking to grinders here in the USA as to why they make a camshaft that has a wide LSA or a ICL at 110 degrees. Most of the time if it is a street performance vehicle then the big word is EMISSIONS . If you buy a custom racing camshaft they can do anything to build the power with what you have and too bad for the bunny rabbits.

There are just so many factors in camshafts that it blows my mind! Yes even an old Gear Head is amazed. The separation angle, wide angle, smoother idle, more flat torque, less power loss due to over lap. The big change in camshafts really came into being in the mid 1980's when electric fuel injection, EFI, was combined with the in car computers, ECUs. One thing I did was to see how moving the exhaust lobe around will help or hurt the exhaust scavenge effect that the emissions folks are into. The intake is the same.. air in is POWER.

Now as to what goes where, it will take a novice a bazillion years to compute the combos. I choose to use my 45 years of making cars go fast. The issue I have is that the specs are sometimes incorrect and possibly misleading. So how does one know what they buying? How do you recommend what cam to use? Newbies will say "I have a 350 cam it it rocks for me." I say 350 what - lift, advertised duration, duration at US sec? So I am trying to qualify things.

I am working on 5 different cams. One for a R50, an aggressive one for a R50 or light modded R53, one for a more modded R53, one for a short track R53 and one for a long track R53

Next, what an adjustable cam gear does

 

The misunderstood Adjustable Cam Gear or ACG

In another thread where I am making posts relative to the installation of a ThumperHeads TPR2, I have noted that I am sending my RWM Dominator Cam to Mike Schultz aka Thumper. Some MINI owners know that Newman makes/grinds the cams for RMW. Newman posts information on their cams but RMW does not provide a "cam card." Without this card it is difficult to figure things out but not impossible and by sending my Dominator to Mike, he will be able to figure out the lobe separation value along with the "straight up" point. Straight up is the point where the cam intake lobe is straight up that equates to the valve being fully open. The last thing Mike will determine is whether there is any "ground in advance" where the cam is made with timing advancement. You determine this by subtracting the intake lobe centerline from the lobe separation. The Dominator appears to be very similar to the Newman PH 2 and Mike already has a PH 2 so he will be able to see if the Dominator is the same. If there is no ground in advance then the ACG will lower the range that the torque band starts and that is what I am looking for.

The below video is a good animation of the how the cam works.


In my 5th post here I tried to explain how a tight or wide LSA impacted the engine. The goal with a ACG can be either setting an engine up to have the torque in a lower rpm range by advancement or moving the torque curve higher in the range by retarding. If you are tracking the car and you have some long straights where you can get the most from an 8,000 redline in higher gears then a wider LSA or retarding with an ACG may help. If you are autocrossing and you want that low end torque curve then a tight LSA or advancement with an ACG could be what you want.

Gee, wouldn't it be nice if you could have an ACG that would automatically retard to get the benefits of a wide LSA for a good idle, advance to get the benefits of a a tight LSA for times you want to step on the gas and then back to a retard point to get the wide LSA benefits when you are cruising on the highway? An Automatic Adjustable Cam Gear, AACG. That would be really great.

Well guess what, the Gen2 MINI has this AACG but in this case BMW calls it VANOS . . . . . . . . . . . .



Next, Mike talks about what he has accomplished with the ACG that he sells.

 

Interesting, that

 

???

Lobe center angle and cam center line are two different things, not "really" connected. The action of these two things is very different from one another.
Advancing or retarding the cam are not...changing the lobe (int. vs. exh.) center lines. And advancing or retarding the cam is not...accomplishing the same thing with the power band that changing the lobe centers is.
Changing the cam center will raise or lower the power/torque curve as explained above, but will not alter the power the same way that changing the lobe centers will. Again, two completely different things.

Or...did I miss something in the above explanations ?

Mike

 

Does this make any sense?

 

My last response above in red is not completely true as based on how the cam is ground the Adjustable Cam Gear can increase torque on our MINIs by five to 10 Ft Lbs across the entire power curve. Using an average of 7 additional foot pounds of torque and at 6500 rpms that is just over nine horsepower. A very nice bump for a part that costs around $250, very nice indeed.

I am working on a post for tomorrow where Mike Schultz, Mr. ThumperHeads, talks about his 40 years of experience with Adjustable Cam Gears. Some good stuff along with some dynos that reflect the numbers I mentioned above.

 

Gear Heads and Adjustable Cam Gears

For me, finding somebody like Mike Schultz with his wealth of engine modification knowledge has been great but even better is the fact that he is willing to share the knowledge. In this post I ask him specific questions on the Adjustable Cam Gear, ACG.

So when did you first lay your hands on a ACG?

The first time I changed the cam phase with ACG was in the early 70s on my 1967 289 Mustang.

Any other cars involved?

Back in the day it was quarter mile time and I was into that big time. Along with my own car I also did ACG work on big block; Fords, Dodges and Chevys. Cloeys makes a 3-position gear for the small block engines with adjustments of either +4 or minus -4 degrees. Jesel belt drive can change every 1/2 degree for real racers. Pete Jackson gear drive came out in the 60s for race cars running high pressure solid valve spring trains.. There are Timing sets that have 9 positions 0- 2-4-6-8.

The ACG changes the cam timing, phase as you call it, but along with moving the torque curve, what else can the ACG do?

For those willing to spend the time to learn, it can raise the compression and higher compression equals more power! This has to do with the ICL. The ICL is different than the LSA. Lots of cams out there with ICLs of 110 and if you have one of those, the ACG is your ticket to drive! The ACG can get that 110 down to around 102 and then you will be rocking! I built a cheap ole 302 for my little street cruisin 72 Pinto Wagon, a fun car. The compression ratio was too low for the camshaft I had, about 135 PSI. I advanced the cam and raised my compression to 155 psi and rocked!! Now remember the ACG works both ways as when I first installed a 429 SCJ between the rails on my 67 Mustang back in the 80’s, the traction was crap. So I thought I would retard the cam and kill some torque. Less torque, less wheel spin. Big mistake, I could barely get out of the garage, so I leave it as is or advance only. Like I said, you gotta be willing to learn.

Wait, you are talking about raising the compression and I thought that also raises the EGT?

OOOOOO, EGTs are higher. You know that at the perfect air-fuel ratio of 14.7 to 1 the EGTs are the highest? Well they are. At WOT you don’t want that 14.7 you want more like 12 and then with forced induction engine you want something around 11.7. You change the cam phasing with ACG, you change your spark timing or your fuel values and your EGTs are just fine. I work with ByteTronik and they know based upon the ICL what they have to do with tuning. It is no big deal about EGTs.

I am thinking the Vanos in the Gen2 cars must work with the ECU in modifying the spark setting or fuel mixture as the Vanos solenoid changes the cam timing. Am I correct?

Wow, give this man a prize. Of course it does, no smoke and mirrors or magic.

You mentioned ICL, which is Intake Center Line, right?

Yes, the ICL is where the intake valve is open all the way. The number is based on the piston position. The OEM Cam and Schrick Cams have ICLs from 110 to around 114. If I change that with my ACG you can gain some nice power. I sent you some dyno charts that show the gains. The first is the OEM Cam and the 2nd is a Schrick. The euros use newton meters not foot pound but there is about 3/4 of a foot pound to 1 newton meter.

 

Hmmm, I wonder what ICL the RWM cams have?

 

I have been looking to get some more power from my r53. I am stumped on where to go though. already have 15% pulley. Aquamist setup and a handful of other stuff. I would really like to see a reliable 250 to the wheels.

 

Honestly, anything over a true 215-220 will require a BVH, small shot of nitrous or complete induction change. It's just a simple fact that the stock or even JCW head doesn't breathe well enough for those kinds of numbers without one of these changes or add on's.

 

A cam is only one part of the equation. In my TPR2 Head thread I recently said: The first thing that came to my mind when I was pulling out of the Speed Shop that did my Dyno was that the first thing you do when you buy a sporty type car is to have a baseline dyno performed. The second thing that came to mind was that you do not get a "tune" unless you first understand some basics of injectors, cams, valves, head porting and Air to Fuel Ratios. Third, if you are going to get a tune ask the "tuner" what A/F he is programming in and why.

BlwnAway is 100% correct. The other major engine parts of the equation are the valves along with the sizes and shapes of the engine ports. A standard rule of thumb is that you need about 80 cubic feet of air per minute, CFM, to generate approximately 115 BHP, which is an approximate 1.44 factor. Next, whereas a RWD car has power train loss factor of approximately 15%, a FWD has around 12%. So to have 250 WHP you would need to have about 280 BHP that equals around 194 CFM. These types of numbers require valves in the 1.8mm/2.3mm oversize range that the RMW BVH, the ThumperHeads TPR2-T have.

 

Will look into a head. Seems there are many different camps on this issue with the mini as there is with any car group. Its winter here in WI lol and the trans is out for a Qualfie so I was just wanting to have a little more fun this summer

 

This is the best option, a BVH is not only the easiest way to achieve your goal, but also the cornerstone for making any additional gains if you so desire later on.

 

Mike at Thumperheads is getting me a cam with a longer duration along with a little more exhaust lift. I am also getting his ACG that he will set to get a lower number ICL. How I want to drive the my MINI on twisite runs is more short track than Daytona Speedway so the concern is more low end torque than high end HP. I am mating the cam to ThumperHeads TPR2 that is an intermediate larger valve head and having Bytetronik do the tune. Mike at Thumper will work with Mike at Bytetronik relative to the ICL setting to address any EGT issues that the lower ICL may produce.

Somewhere in the NAM archives this stuff has probably been hashed over but at that time I was no where near a MINI. I like to do my own research and decide myself if a less expensive system or method will suite my needs. Some may say I am cheap but I consider myself realistic. I review what I want to accomplish and what I am working with, in this case a car that is pushing 12 years old. I also accept that I am not a racer and do not need to point to numbers on a graph to enjoy the car. I have done threads here on an inexpensive fix for the rear trim of the Gen1 convertibles, a $500 +/- big brake kit and a $300 +/- water/meth injection system. I even have a thread on how using a commercial fountain filter can do a pretty good job on simple winter windshield fluid to use in the water/meth system.

The good thing about NAM is that there is a core of good members that enjoy their MINIs and not afraid to make posts about their journeys with the car whether that is a road trip or a installing a short shifter. There are trolls here but for the most part they are controlled by the Moderators that are members of the core I previously mentioned.

 

One of my biggest issues is where I live. Its very very um VERY Rural and I have no Dyno options. Remote tunes are such a pia becasue of nailing down time to do it. So I am dealing with that too

 

RMW can email you a "canned" tune based on what you have and what you will do. He has a large data base of past tunes so he will get it close to what you want. Bytetronik goes a different route whereas you make datalogs with an Air/Fuel gauge that you then send back to them via email. They then create a tune based upon your specific engine and your specific mods.

I have a RMW tune now but will have a Bytetronik tune when I get done with the ThumperHeads stuff.

 

I always worry about mixing manufacturers stuff ie tune vs someones elses head. Seems this car (Mini) is no different than others with vendors pissing on each other. Good options though and I await your experience. I have talked to Mike before. I am just not wanting to give up my head for machining as its like new. I need to find a good core or just bite the bullet and pay the fee. I would hate to ditch a 40k head.

 

Is the car running good now? the two mods that will add the power ( other than a tune ) IS the head or camshaft. Both in the conservative size will add power and NOT need a tune. 25-35 WHP is do able with the stock parameters in your current ECU. Any person that tunes can and will tune your engine. There are no tricks here. I have been told the Mynes Bytronics are better over the RMW, and then vice versa on the RMW vs Bytronics. Myself ? Bytronics. . Get a Head off Thumper Performance TPR1 or TPR2, and now they have some good camshafts. .410/.374 drop in HP or a .405 / .371 drop in HP. And if you need a tune, anyone can do it for you. You should be in the 220-230 HP before the tune.