Flat tappet vs roller cam

[hydrolastic]

Hello Guys, Looking at my mini roadrace engine bMC A series I got to looking at the camshaft, Got me thinking about roller cams. I know there are more than a few problems getting a set of lifters and the cam in. But without going into the installation part I was hoping i could get some insight into the advantages/ disadvantages. Engine specs are- bore 2.810 stroke 3.2 stroke, seven port head flows 128 cfm on individual runners, FI , equal length exhaust close ratio trans. 15-1 Cr, 110 fuel
Anyway lets look at the cam and power of the engine now about 90 ft lbs at 6500 and 110 hp at 8500 this is with the current five port head the cam has 300/300 duration and .5 lift It currently runs like complete crap below 4500 but hits the cam hard and pulls like a train after 5000. perfect for a roadrace engine as it never get below 6000 during the race. It occurred to me that if i used a roller cam I could get the same airflow with less duration. Getting the power at less rpm would be a good thing so lets say 5500 to 8000. And more torque overall.
So because the cam has more area under the curve it would flow more from half lift to max lift . More air throughout the valve motion. but say i want to keep the airflow volume relatively close to the same this means i can run a bit less duration for more torque at a lower rpm and still keep the power at the upper rpm. Right? In other words how does a the power curve change when you go from a flat tappet to a solid roller cam?

[raceman14]

Are you talking mini cooper???

I think there is more power in the heads to begin with, and for sure I would always take a roller cam if budget and availability would allow it. Now there is a pretty big learning curve on going from flat tappet to roller, as we did it in ARCA engines, BGN and CTS engines and it was pretty damn hard to beat out a flat tappet for power and torque and it was some cheaper with flat tappets. I think one of the cam experts I talked to either Harvey Crane or Harold Brookshire told me it is difficult to get the same intensity of opening with a roller -v- flat.

Needless to say it only took about 3 roller cams for us to hit 800HP and a couple more to hit 850HP on SB-2's and then we were in the range of a XXX Qualifier Cam that would run all day long.

What are your cam specs at .050" and what is the lobe separation and where do you have the Intake centerline.

Back about 20 years ago I started porting heads for a company called "mini-mania", the guy ( Dick Faille ) that ran the place set a bunch of records and won a bunch of races with my stuff"

He was having his stuff done over in England and I had him bring me a race winning head and a couple stock heads for me to play with. The port and polish work looked pretty and shiny and the valve job sucked. The head made a lot of noise on the bench and did not flow as well as a Ford or Fiat 2000 which I had done a ton of. Took a bit of work on getting some good valves to match the port and then getting the valve job to do as well, after I got that ciphered the little 1600 head came alive.

Come to find out my head was about 40hp better on his engine dyno and he was going nuts. The second head I did was another 10cfm better and yielded another 20HP on the dyno. I ended up doing probably 20-25 more heads for him and his business.

I think I ended up losing mini work because I started back doing Kick-A$$ Fiat stuff for Gary and John Baucomb and they ran in the same classes and took over winning all the races shortly after getting on my head and cam program. The Fiat DOHC with a Ferrari intake port, chevy rod and stroke and pretty nice everywhere else. It was way easy to make 200hp 2.0L. With the cam gears I built I could roll each cam where I wanted it so lobe separation was not a problem and it was effortless to tune the engines. I think we turned one of the dyno engines to 10,500-11,000 rpms and it ran up there effortlessly. I had Carrillo rods on a stock lightened crank and Mahle race pistons. I used stock rods and pistons and turned 8500-9500 all the time.

I do remember the common port head and the other head and I think the common head made more power and the independent port head flowed better. Possible I got it backwards as it was 20 years ago, I need to go back and see if I can find that box of papers, I know they are on a pallet somewhere.

[Jarmo Y]

Are you sure about your heads potential, maybe it has more work needed than camshaft? An friend of mine drove Mini 1300cc roadracecar about 25 years ago, it was over 100hp at 11000 rpm with original head, not billet and with his own camshaft. He is also camgrinder even today. He has an roadracemini still left, talking about love to those cars

An picture about billet head..is that intakeport really powerfull, I dont mean cfm-vise and why must you have FI nozzle direkt to the head?

[CamKing]

Come to find out my head was about 40hp better on his engine dyno and he was going nuts. The second head I did was another 10cfm better and yielded another 20HP on the dyno. I ended up doing probably 20-25 more heads for him and his business.

an added 60hp out of a 97ci engine

[sanfordandson]

in another post raceman14 is claiming he ran lmsc engines with a 350 holley up to 8200rpm...i bet that sounded neat!

[raceman14]

Sanford,
I never said we weren't pushing every rule in the book. I can tell you that engine won over 1/2 of the NASCAR races in the Southeast region that year and almost won the National Points Championship but a guy in TN had more points with the same wins due to greater car count.

You might want to check rules before you go shooting your mouth off about how you think an engine would run. Rules changes that year opened up the manifold rule & allowed dry sump pumps. I ran a Prototype MacFarland, a 3 stage dry-sump with 2 vacuum stages and one pressure stage. The engine ran 8200 and sounded just like the Kodak Car the won Daytona with Runt Pittman engines. There was a specific reason to run the engine past the power band in the corner and if you had any knowledge whatsoever about why, you might understand what I and many others were doing. We still do it with crates on dirt and it works.

Here is a major clue, the short block is an air pump and continues to pump 20-30% past the capabilities of the carburetor, even if it pumps with no effect on intake pull it still operates as an air pump. You have seen it and I have described it on here a dozen times. The reason I ended up using it is because it casues peaks on the chassis dyno of 600-800ft/# depending on the engine and the speed of over-rev.

By the way the exhaust system we ran was a prototype system I ran for Dr.Gas, funny how that same system appeared on the Kodak car the following years. Boyd appreciated the help and always kept is in the best exhaust systems even though we could not afford them. It was good to have the Salt Lake connection of Bill Jones, Red Hale and Mikey Chapman, it really helped my race program a lot.

[raceman14]

Oh yea camking,
Glad to see you can add. Like I said those numbers were from his dyno and not mine, that engine that started off with 100hp went to 140 and then to 160 and that is where we stopped. The Fiat program surpassed those numbers like I said and the Baucomb's owned their own engine and chassis dyno and supplied me the numbers.

In my world mild street engines make 1hp/inch , good race engines make 2hp/inch and really good engines make 3hp/inch. I am pretty sure there are a couple engine builders on here or head guys that know their way around and engine that would agree.

I did chassis dyno a couple of the cars and they were a little less on my Superflow but both customers were running on an older Clayton dyno that was probably a little happier than mine. Mine was custom built with a 3800# wheel to test CUP cars on so anything I run on it always accelerates way better on the track and usually produces about 5-7% more on a Dyno-Jet. I have confirmed that on Import Dyno days along with a bunch of street cars that brought their Dyno-Jet sheets with them.

The MINI heads and intake were poor at best, and the valve job was cobbled, even though he was paying $2500 a head to get them ported and built in England. I ported and flowed valve jobbed them and built them for $1000 after I did the first head for FREE as a learning project and to get his business if possible. From that point on I did a couple a week and was happy even after I found out that I was less than 1/2 price. I did the work for what I thought was fair and he was happy as hell cause I picked up and delivered to his shop with a 1 week turn around, no shipping and duty and all the rest.

I did the Fiat heads for the same price and did a ton of them, built a bunch of Oval track Fiats and I think we had about a 3 year run in Mini-Stock where the only 3 Fiats around swept the podium on a regular basis. There was a ford 2.0 every now and then until they outlawed the Fiats and made them move up to Modified-Mini Stock where they were just as dominant.

Its not my fault some racers are too dumb to push their thought processes & engine programs past limits that folks talk about and write about as fact. I am not in Charlotte, or Indy or CA, where there are large pockets of racers with that follow the leader mentality.

I am sure you build cams for a lot of folks, I am sure you see one in a thousand that is far beyond the rest and it is usually reflected in how they run on the track.

Don't really matter, I got paid, and the customers were happy and winning races wherever they went. I post on this site to find the 1 in 1000 racer that wants to stretch the limits on what he can do with his engine build or race program.

My thoughts on this mini deal was the fact that it is in the top 1% of engines in that family but not reflective in the flow number out of the head and I figured a top effort 100" engine should be all over 200HP no matter what the brand.

I am working on some 2.5 Nissan stuff now and it is a nice head and I am shooting for 100hp/liter N/A. Last engine was just a mild port job with stock valves, cams etc and was around 203hp. New engine with a Yoshimura Intake lobe and Jun exhaust lobe, 300Z rods and pistons, Indy Ti valves, ported and milled head with dish pistons and 10:1 compression I am shooting for 250HP on pump gas.

[hydrolastic]

Thanks so far guys, I have no doubt that race 14 did what he did. i would guess in the early eighties that was a time when the bigger is better camp won out in the valve and port size wars. Later it was developed a bit more and 125 hp at the wheels were seen from stock stroke (3.2) and .040 over blocks in the sprites and midgets. Minis a bit less with the sidewinder transmissions. All of the hp's i have stated are wheel hp as i have no use for corrected crank hp. So far with the five port or common port as race 14 calls it i have not been able to break 112 hp but that was with a 320 cam that was so peaky i could not drive it well. a better driver would have probrably loved it. That cam was retired last year and i want to get back to torque over hp as it seems to me that power accelerating is better for time than maximum power at the very top. At least for the way i drive.
What i would like to get back to is the specific advantage of the roller cam. And to take care of the five port or common problem so i went for the seven port head. The photo i provided was the stock port at 110 cfm cause my engine builder is a bit wary of showing the finished stuff. Personaly i don't care as this is a vintage car and the wars are (almost) over. Just having fun at this point. But the head was shown so you can see that this is not a five port head. I expect this head to be able to use exhaust scavenging which the five port cannot do. and get the intake to get a velocity charge. Schmidts engine designer says i need just shy of 160 cfm to get maximum power out of the engine. I did not go all the way there (yet) cause i want to go toward the gaining torque side of things. Last year Stan Weiss had some very useful things to say and his comment on the fact that the power would stay about the same was spot on. with very little improvement despite a whole new design on the lower end ( More squish , compression, long rods, etc )
This head should be able to take advantage of the roller cam as it seems to me more air from half to max lift is just the ticket to jamming more air fuel into the engine at just the right time. So again what are your specific experiences with switching over do I just duplicate the best flat tappet cam on lift and duration and LCA's hoping that the extra area on the cam will work or is there something to know about getting the most from a roller cam that could be added . Thanks Aaron

[sjvalleydave]

One question for Raceman14...I was reading a thread on the advanced engine board regarding HP, Torque and Acceleration Rate which is right up your alley, and I don't see any posts from you discussing this with them. I cruise that section occasionally and haven't seen you post over there. I might be totally wrong, just wondered why you didn't get into some of the theoretical deep discussions they have over there...

[sanfordandson]

b.s might be a tougher sell over there....

[MidgetMotorsports07]

b.s might be a tougher sell over there....

I was wondering when someone was going to point this out.

[Dodge Freak]

You mean we are not going to have 250 hp n/a two and half liter 4 bangers in a few years in many new cars

[jpankey]

I dont know what the lifter in a mini is but I have often wondered on a four cylinder engine that I am familiar with that has a mushroom lifter with a 1.5 inch diameter if any thing would be gained by going to a .750 roller wheel other than being able to increase valve spring for possibly more lift but the cylinder head I deal with is done at flatt tappet lifts. I lean toward the smaller roller being a disadvantage in my case.

[raceman14]

Dave,
Thanks for the info, I have posted on advanced a couple times when I have had pertinent information. I'll look for the thread you are referring to. Best as I can recall it is in relation to the Engine Dyno used that the Carb Shoot-out. MLR is the best reference there as he is co-inventor of the system.

My inertia experience is at the rear wheels in relation to my Superflow Chassis DYno, and I would be happy to discuss that anytime with anybody that wants to.

I don't post a lot on theory because the projects I do on a daily basis are what is happening right now at the rear wheels. What I do is take theories and either prove them or disprove them and add them to the list on my logic trees. When I have time I go back and push further for myself in an effort to learn why something failed or why it succeeded as I get paid on a regular basis to develop doo-dads for folks.Good example, I have developed a really nice header for 604 crate engines, I want to see what a change will do for version 5 of this header so I have Joe the header builder build me 3 variations of the same header and test them. I prove my theories as one of the 3 will always be better than the rest and it may not be the one that I thought it would be, that is why I don't write a lot about theory because 50% of the time it ends up being wrong. I try to eliminate that and only discuss the stuff I have done that makes power.

I had a theory on Boosters for 604 Crate Carburetors, I built 5 different versions of the same 750 carb and tested them on Johnny Pruitts' DTS, Darrel Gabriels Froude, Willy's SuperflowChassisDYno and my SuperflowChassisDYno, the different carbs have also been tested and have won National Events in Fastrak, Ne-Smith and UMP it took about 6 months total to get it done and I now know what works best. As far as what worked best, it was the carburetor that supplied the best fuel emulsion for the vacuum draw of the engine, just for those who will understand all of my testing was done at 5psi at the bowl, with a bypass on the fuel rail back to the tank.

Did you have a particular question related to Chassis DYno?

Dodgefreak,
If you are doubtful of 100HP per liter you might want to step out of the 70's and check out some of the new import numbers as Honda has a 200HP 1.8 liter, that runs on pump gas with a pretty small camshaft and gets 30mpgs. I think the Subaru is around 230hp on 2.5L NA engine, and I know of a couple that have run at Commerce that were close to 275 with cams & porting plus a new FI map.

The engines I am referring to are, race engines with particular care taken to match the intake manifold, camshaft and exhaust system with Helmholtz-Resonant tuning. If you have the proper FFT equipment you can tune an engine just like an instrument as the air flow responds just about the same way in an instrument, speaker and race engine.

I did one of my original FFT projects about 20 years ago with a guy name Jim Fueling, after a cold beer and some jottings on a napkin at Superflow in Colo.Springs I got invited out to CA to work on a Salt Flats project that was stalling fuel in the intake manifold of as Salt Flats Quad4 for GM R&D. After the installation of a couple electronic piezo tweeters to jolt the fuel supersonic with ultra high frequency energy the results were pretty amazing on the dyno ( it was over 100hp gain right off the bat, and more once we introduce larger injectors ) and on the Salt Flats. Did not make the Salt Flats test but it broke the old record by over 30 mph.

AIR is air, it don't know the difference!!!


Hydro,
Camshaft is a big part of your problem. Over 300* is absolutely unnecessary and as I stated before I am sure you are running wide lobe separation to fill in for absence of torque when your valve opening and closing sequence off. 8500rpms is workable with cams in the 275-285* range and 255-265@.050", if you have proper valve positioning in the head, decent intake and exhaust system with proper cylinder to cylinder scavenging. In any race engine known to man, you can almost never open the intake valve too soon, most engines also respond to early exhaust closure to maintain cylinder pressure so you have to balance those 2 requirements to minimize your losses.

Valve positioning in a flat combustion chamber like Mini, Ford 2.0, Fiat etc can be as much as 30HP on 150HP engine.

Jpanky,
As far as cams go, roller wheel diameter in comparison to flat tappets is a not an easy comparison. You gotta go way big on a wheel to make up for big flat tappets. If you measure duration at the valve on your engines you will come to understand camshafts a whole lot better.
Rollers are better on wear and longevity in most cases but it is hard to beat a good flat tappet on area under the duration curve for similar size lifters and duration.
I would personally select a roller all else being equal because I can cram a bigger/better valve spring in there to control the valvetrain.

[63bobby]

Raceman14 I rember reading about Jim Feueling and his quad 4 motor . He also made a 4 valve set for the HD which I have a complete set To bad We lost him
He had a lot of cool ideas .