RCS Racing Engines

RCS 2014 Engine Masters Challenge Day 4

RCS 2013 Engine Masters Per Testing at RCS

RCS 2013 Engine Masters Challenge Day 3

How things went

With the new rules being announced at the 2012 PRI Show, we got an early jump on the 2013 EMC, or so we thought. Our first thought was to build an LS7 as we expected so many others would follow the LS trend, while my eyes focused on the Modular engines and like others we were concerned that top end power would be low. The CHI head Cleveland was attractive based on the rules, but the block was a big concern from the BS on the web about OEM Cleveland blocks. CHI heads had a good past at the EMC, and I expected it to be a consideration from others when using an aftermarket cast or aluminum block. As for most engine builders but a few, cost is always a big consideration when many of the part sponsors don't make the types of parts we need to use when developing an engine combination. So we decided to go with the Cleveland CHI head combination, but in the back of my mind we were still working with a 45 year old valvetrain and engine design, which could be a problem, while the LS and Modular engines had 45 years of modern engine design already, making it easier for most to create a good power curve.

Knowing our abilities in head porting and design, we felt the CHI combo would make more power per cube than the larger port LS designs. We have never seen a set of CHI heads or intake at this point other than some pics from websites. We ordered our heads from CHI in January 2013 and it took 5 months to receive them, and it took an additional 2 months to get the correct intake manifold. This caused a huge inconvenience for us in the time line to get the engine finished with our ongoing work load. We tried to explain to CHI the importance of receiving our heads and intake in a timely manner, but unfortunately we did not recieve them as we would have liked. After inspecting the intake manifold recommended by CHI I informed CHI that I needed a smaller 4150 style flange instead of the large 4500 flange, which took another 45 days to receive. We informed CHI if we would have known the time line on parts we would have built a LS7 engine instead.

Cylinder Heads

After weeks of designing one intake and one exhaust port along with the combustion chamber, we digitized them and then wrote a CNC program to finish machining the rest of the ports and combustion chambers. Once the heads were finished on the CNC 5 axes machining center we had to tweak them by hand to get them balanced within .5 of a percent on the flow bench. Final flow values were 300 cfm at .400, 350 at .500, 380 at .600, 400 at .750 and 400 cfm at .800. The unique design of theses heads yield an intake runner volume of only 246 cc's with a minimum cross sectional area of only 2.4 sq. inches yielding a 1.61 flow to port ratio per CC of volume. If anyone has researched CHI heads you'll see similar flow rates, but with a minimum cross sectional area of 3.1 sq. inches, which we don't recommend for single 4 barrel intake manifolds or really any engine because they are way too big, unless you had a very large engine to keep up the air velocity.

Intake Manifold

The second problem we had to get over was the low intake runner design the CHI intake has. It is very difficult for high velocity air entering the plenum to turn into the runners when the angle into the runner is more than 30 degrees, even though the individual flow rates of the manifold and head combined were 380 cfm. We knew this much air per cylinder would never make it through the turn of the manifold and would hurt our expected top end power of 770 to 780 Hp. While the throttle body flow rate was 1,375 cfm out of a 4 barrel 4150 design, we knew it was more than enough to feed the engine demands. During testing the air column entering the throttle body came to a stop at 6,500 due to the turbulence created by the plenum runner design. Now if we were allowed to install a 2" or more spacer under the throttle body this would allow the air to slow down enough to make the turn into the runners, but unfortunately we were not, only allowing .625 of an inch, which included the gaskets.

As for more on the intakes designs we recommend using CHI's 4150 manifold with the smaller runners. We had to add epoxy to the head side of the manifolds to make the ports smaller in the manifold to match our ports in the heads. We also had to straighten the 4 center runners, as well as the 4 outer long runners, adding epoxy to move the walls and creating a straight path. With these modifications we were able to increase the intakes flow rate per runner 30 cfms when bolted to the head, retaining the minimum cross sectional area of the port in the manifold. CHI products are very good and are great for making power, but as for all manufacturers there are limitations when working with 45 year old engine designs. The modern LS family already has 45 years of technology added to its design, making it much easier to achieve similar power outputs.

4 Valve Heads

The modern 4 valve modular engines ended up being the correct choice for this year’s challenge with a huge advantage of more valve area and a smaller port cross sectional area, making it the engine to build with its low rpm torque potential. The long intake runners aid in filling the cylinder, increasing volumetric efficiency very early in the rpm band, but restricting cylinder fill at high rpms. When choosing an engine one has to look hard at its ability to make its power where you need it to. If you don’t have the experience in a particular engine design you have to make contact with people that do know and hopefully you will get good direction in building your combination. Many of the top engine builders do this to gain an advantage on the not so lucky that are not fortunate to have a popular name in the industry that opens doors for information. Money and who you know makes winners in this industry today. It is not always your personal knowledge and talent.


The demons that can plague a shop can knock the wind out of anyone’s sail. This is our third year at the EMC and we have been plagued with failure of manufacturer's parts and the inability to get quality parts. We nearly never have problems with customer projects and it appears to be only when we are in the challenge. Although we work through them, the time it takes has to be allotted. If not, you will surely run out of time, as we have three years in a row now. When you don’t get a chance to take care of every little detail trouble is right around the corner, and it usually shows up at the challenge.

OEM Ford Cleveland Block prep

We decided to use an OEM Cleveland block that we found in Canada; an early CJ 4 bolt main block that had some rust issues in the cylinders we weren’t aware of until we put a hone to it. Three of the cylinders had to be sleeved and it took .020 to finish the block to size. Our original design was to sleeve the block down to 1.mm (3.9275) but after finishing the heads we had clearance issues with the exhaust valve clearing the cylinder wall. This combination with a 4.250 stroke put the engine at 412 cubes, but unfortunately we couldn’t use the idea. The block ended up with 3 sleeves and a finished 4.021 bore. The issues that everyone seemed to be worried about were cylinder wall cracking, front main webbing cracking and the oiling system as a whole was poor for a race engine. Well, I have to say I also became concerned after hearing all the BS on the Web about the Cleveland block. While machining the block it was obvious that the block was high in nickel and the concern of failure became less and less. Fixing the oiling system was easy, a perfect line hone of the mains with ARP studs to start with, with .040 oil restrictors in mains 2,3,4,5 to the cam bearings. A must is to install bronze lifter bushings with a .060 oil feed hole located directly where it is exposed to the lifters feed holes at all times of the lift cycle. This will assure that the valvetrain gets its required oil. With those two services done you have restricted most of the oil leaks in the engine directing the majority of the oil to the mains and rods. Take special note that the oil feed holes in the block to the mains have to match the main bearings, so machining the oil hole in the bearing to lineup with the block is an absolute must. Never use full groove main bearings never - - never, ever. We had a chance to view our bearings at the show, Popular Hot Rodding is doing an article on the engine so we got a change to look it over. As the pictures will show our rod bearings look like they were never used even though they had 50 or more dyno runs on them. Most people do not understand bearing clearance and how to achieve the correct clearances. Bearing clearance is a by-product of journal size, bearing width, temperature of the oil and water during operation, oil availability, and the amount of air present in the oil, viscosity, and volume/pressure applied to the bearings. We have found when all of these areas are considered, bearing wear can be illuminated. When the correct clearance is established the bearing should never touch the journal of the crank, floating the bearing with the loads applied across a film of oil. So the key is to set the clearance according to the growth rate of the crankshaft. In short, larger cranks require more clearance while the smaller ones less, which includes the overall mass of the crank not just the journal size. I believe the myth that Cleveland engines have terrible oiling system is due to inexperience and lack of knowledge. Oh by the way, never use a high volume oil pump when doing these modifications to the Cleveland’s oiling system. We use a standard pump with a 1/8 thick spacer washer behind the pressure spring ONLY! Our engine had .002 clearances on the rods and .0035 on the mains. This will create over 140 lbs. on throttle when cold, and within minutes when the oil temp increases to 120 to 160 degrees you will have 30 lbs. at an idle and 85lbs at 7,000 rpm when using 10w-30 viscosity oil.

Front Main Web

Let’s talk about the front web breaking. The stories I have heard is that the block is weak due to the main oil galleys that cross through that web. The picture I saw of an engine that had this happen - yes it was obviously broke, but why and from what. There are many reasons this could happen; crossfire in the cylinder, imbalance problems of the crankshaft, and poor engine design and assembly. I feel the main reason is imbalance in the crankshaft. It is critical that the balance of the crank be internal and be within .5 grams or less from end to end. All bob weights and components within .2 tenths of each other and as for flywheels and dampers the same .2 tenths. When a crankshaft is out of balance the ends of the crank will oscillate, creating unwanted loads on the front and rear mains. The forces that are applied to the crank also have to be equal to the other cylinders as well. All crankshaft flex during the loading and unloading of the pressures. We used a 48 lb. Scat crankshaft in this engine, an Ultra-light, which under these loads applied flexed between each main web and journal. My thoughts were to allow the crank to flex and not the block, taking the load off any one individual main web. Inspection of the main bearings show that the majority of the forces were applied to the top bearing and not the bottom as you would typically see. It is also my opinion not to over or under balance a crankshaft. All this does is put it out of balance, creating potential problems.

Cylinder Walls

Lets talk about the cylinder walls. Yes, all cylinder walls flex. It's part of the operation, but our goal as engine builders is to apply the pressures to the piston and not in flexing the cylinder walls. The only thing I can say is the faster the piston speed is, the less pressure or stress any one part of the cylinder wall will see. That goes for the rod ratio as well; the lower the ratio the faster the piston moves during direction change. When we installed the three sleeves we bored the block to 4.155 and once sleeved, bored and honed the finish thickness of the sleeve was .067 thick.

Manufacturer Parts Let Down

Let’s go back to the events that haunted RCS from doing well. We were on the dyno at RCS and we have no spark, the engine was already broke-in with a carburetor and MSD ignition and the engine ran fine. We switched to fuel injection and converted our magnetic pickup in the MSD distributor into a cam pulse signal for sequential injector firing. Unable to establish a strong enough signal the Holley ECU could not hold a repeated signal from the cam pulse. So we had to eliminate the cam pulse and go with timed sequential injection, which meant the injectors would follow the firing order, but would randomly start firing, and not like sequential where we fire the #1 cylinder at 195 degrees before TDC firing, which allows each cylinder to see injector firing 15 degree before TDC on the intake stroke/cycle. We also had a data logging communication problem and O2 reading issues. Holley came to the conclusion the ECU had to be returned to Holley for service and updates. This left us tuning the engine like a carburetor, adding and removing fuel to the map during each pull to get a basic tune-up. On top of this our dyno lost the internal seal in the absorber and we couldn’t pull the engine any lower than 4,600 when loaded, so we were blind on the tune-up and power for 3,000 to 4,500 until we did a pull at the show.

Give it all you've got

Not being able to see any power outputs from 3,000 to 4,500 we had no idea whether or not we had an exhaust scavenging issue, an ignition timing issue, a fuel ratio issue or all the above. So we went to the show blind in that area, hoping to get a handle on it there. To our surprise we were way off on the exhaust design. The engine required additional scavenging from 3,000 to 4,000, which created a huge rich condition in the 3,000 to 4,000 rpm area as a by-product, due to reversion in the induction system and with a fuel injection engine that's bad because the injectors are still firing, delivering fuel when the air flow has slowed. Not having an O2 correction to help, we had to manually remove fuel from the map. As much as 30 percent of fuel was removed at low rpms and we still couldn’t wake the engine up, which really hurt our score. The main issue was exhaust scavenging, but there wasn’t anything we could do about it at the show. We were also down on our projected HP of 770+ as well, but that was due to the intake manifold design I mentioned earlier, so will have try it again next year. Good Luck!

RCS 2012 Engine Masters Challenge Day 2

The RCS qualifying session is at the 3:41 to 4:40 time line of the video.

At the shop of RCS with a final tune, our 499 B/B developed 1,079Hp at 7,600 and 825lbs at 6,000 rpms. That's 2.16Hp per cube with peak torque efficiency at 825lbs an astonishing 1.67 lbs. of torque per cube equaling today's NHRA ProStock engine efficiency output, but at 6,000 rpm's instead of 8,500 where it's easier to make peak engine efficiency happen.

Due to the summer work load we were unable to spend any more than 4 weeks building our engine for the 2012 EMC, putting an enormous amount of stress on us to get the engine ready for the challenge this year. The project was haunted with demons at every corner. The intake manifold turned out to be a work of art in just getting it to fit the 9.300" deck height, while a battle went on with getting the intake manifold runner design to work in our favor, and finally not even a day before we had to pack up and leave for the challenge, it all came together. We used one of Sonny's Automotive new cast single four barrel manifolds designed to fit a 11.500" deck height block, which required us to cut and re-fabricate it to fit our 9.300" deck height. In the process we used over 2 gallons of epoxy to redesign the runners and internal surfaces of the manifold to get it to work with a two Dominator carb setup. One of our goals was to lengthen the intake runners by 3 inches reducing the cross sectional area of the runners.

This is our second year as a competitor at the EMC and we are still learning how the computational linguistics works. When we got to the challenge this year, I discussed with the DTS Dyno operator as well as the manufacturer of DTS Dynometers,  what we might see as power results on the DTS dyno compared to our SuperFlow dyno and they both predicted that the dyno’s should read very close in comparison.

Well to our surprise we were 87hp short of our shop’s dyno cell and dynometer readings, only making a peak 993Hp. During the challenge dyno sessions we came to the conclusion, after changing 8 jets twice on two Dominator carbs, leaning the engine’s fuel requirement down due to a slight humid condition in the cell, while also checking for broken valve springs and valve lash or part failure, we were fighting another demon. To our surprise the changes we made to the engine’s tune-up made absolutely no change to the engine’s power curve or outputs during the five dyno tuning sessions. We were fighting not an engine tuning or mechanical problem, but a dyno cell engineered condition, and there was nothing we could do about it. This condition can affect engines differently based on their design and size. The top competitors that have been competing for a number of years are aware of this, and I’m sure they are adjusting their engine designs based on this.

With our second challenge under our belt we've come to a conclusion. We should be building the engine to work with the dyno cell that we must compete in. Engine dyno cell designs are critical when it comes to developing a well-designed and tuned engine. Exhaust systems that are at 30 ft. long and with forced air ventilation systems feeding the dyno cell can really be departmental to high breathing capacity engines that move a lot of air through the engine. The trick would be a single four barrel small displacement engine..... not tunnel ram engines with lower air speeds through the runners and engine’s that breath a lot less air as a by-product focusing the engines design on creating as much efficiency from the CFM’s going through the engine.


After the challenge we checked the engine over and found the reason for the loss of power, a closed spark plug gap, it closed all but .005. With the use of aluminum rods in this engine and a new piston dome design we thought we had this problem taken care of days before the challenge up to the last pull on our dyno things were good to go, but the demon can out at the show and no one even considered this as a problem so no one checked the plugs at the show mostly due to the timeline allotted. See how stuff can happen to anyone at any level. Next time hopefully.