OK, toss out everything I know... Dulcich, chime in here...

[Caveman Tony]

Fall edition of Engine Masters:

Dave Storlien (Porting Dynamics) built a flat-tappet LS motor... Article called "Unconventional Powerhouse"

Reasoning?

"I wanted to show that the flat tappet would make more power than the roller"

He used .904" tappets... article stated "flat tappet had 0.042" more valve lift at peak flow demand"

That's point A that blew my mind.

Point B?

A caption next to a pic of a fairly carbon'd-up piston top:

"Dave tells us the ample squish area provided by the reverse dome (dished) piston matched to the combustion chamber helps reintroduce fuel into the combustible mix, aiding in combustion efficiency."

So... if that is the case, why are there big crusty deposits of carbon on the pistons?

Point C?

A caption next to a pic of a tappet:

"...Dave explains that the flat-tappet offers the advantage s of lower friction and a more intense rate of lifter acceleration than is possible with a roller..."

(ok, so the tappets are ceramic faced, but really? Less friction?)

Someone please help me understand all this... I'm about to get vertigo, and I don't wanna end up on some ricer website...

[Barry Donovan]

solids do more through low mid even into high ..but higher rpm? I don't believe that.

cruddy pistons could be anything. I actually like the crud. can't get tougher than carbon.

[BOSSMAN]

I had a good conversation with Dan Crower about this subject (camshafts). Has alot to do with the lobe design of a flat tappet when plotted out vs a roller lobe. Valve action on a EMC deal your trying to snap the valve open as quick as possible. The correct term may be major intensity of the lobe, I'm not really a good camshaft guy just yet but I'm learning. When you are looking for any advantage YOU WILL GET CREATIVE! They took the LS roller cam core and ground flat tappet lobes on it. Now the friction thing you can't beat a roller, that just had something more to do with lobe design IIRC. I would image a ceramic faced lifter would slide smoother over a standard unit but valve train control would be a must so it wouldn't beat up the face.

Carbon or black on the tops of pistons means its getting a complete burn, if they were shiny in areas that isn't a good sign. I believe they were limited to a certain compression ratio so they mimic the chamber shape in the piston to add the volume needed.


The things they did I thought was pretty cool and sorta outside the norm. Hope that helps explain some.

[RAMM]

I would agree with what Nick has said and maybe add this. The excessive carbon deposits you see are a result of a complete burn, but also of a very homogenous air fuel mixture in the chamber, in addition to that I would say the shear amount of carbon is from extensive run time (test time--a lot of pulls) for example.

I enjoyed that article and would like to know more about Mr. Storlein's valve event choosing method/formula. J.Rob

[Bob Holmes]

Dave is a very bright guy. I had the pleasure of meeting him at a Vizard seminar in Minnesota. His questions and challenges to David's presentation made the event. Unfortunately, I believe that he was getting ready to retire. He's very creative.

[Caveman Tony]

Totally *get it* that the clean areas on the piston tops were either quench areas or mixture washed (Probably not on this motor) but a light brown coloring of piston tops is NOT ideal?

I always thought carbon was a sign of either too rich, or oil in the chamber.

[oldsman71]

oily carbon is bad, dry is good

[Thumpin455]

To me any carbon is bad, does nothing but wear the engine and cause other problems. Cant get around it with gasoline though, any engine you pull apart that has been running on gas and being worked is going to have plenty of carbon in the chamber. There is no way you can effectively burn all of it in the engine. Quench areas will come out clean, even after years of running, because the fuel air mix is pushed out of those areas, whereas a dish is going to collect more because it has more room for the event to occur, so to speak.

The Mopar lifters have been known to handle aggressive cams for some time. Doesnt surprise me the wider lifter made decent power, you can get really aggressive with the profiles. Not quite the almost square lobes of a roller, but good enough to open the valves quick. Rollers are nice for reduced friction, but the power gain isnt that big from it, mileage will see a better increase and so will longevity... in a street engine. A solid roller can be very hard on the springs, but it doesnt have to be.

[dulcich]

I knew that story bucked a lot of conventional wisdom. Dave is indeed a very sharp guy, and though I wrote it, I wrote it how he told it. Dave seemed to like the article and even sent an E-mail telling me I did an awesome job with it - his words, so I'm confident I did not misrepresent his thinking.

Flat tappet geometry follows the lobe differently than a roller. The lifter can accelerate faster than a roller, but peak velocity is limited by lifter diameter. Rollers on the other hand are acceleration limited but have virtually unlimited velocity (not geometrically limited). D. Vizard explained this to me when I was just a pup, working on engines and learning to port heads out of his old Riverside shop.

Also, think about how a flat tappet dwells at near peak lift as the lobe moves across the flat base of the lifter, as opposed to the linear contact of a roller that will follow rise and fall with the lobe at the peak lift inflection. Totally different operating geometry.

There is a lot to it, and for Dave's purposes the flat tappet was the tool he wanted to do the job, and based on his EMC performance it is hard to argue with him.

On Friction, I really don't know because I haven't done any testing to see results first hand. That's why that info is written as a direct quote. But thinking about it, as Dave further discussed, the flat tappet is riding on a film of oil. How much friction in each type of lifter is something I cant quantify. I think one horsepower is something like 2,545 BTU of energy going up in heat. So if there is 20 horsepower in friction in a flat tappet, that is a lot of heat - like a 50,000 BTU, the heat energy of a big propane heater, and that seems implausible to me just off intuition.

When a free-thinking, open minded, inventive guy with a mind like Storlien is talking to me, I don't dismiss anything he is telling me on the basis of 'Known facts'.
-dulcich

[TheSilverBuick]

I think one horsepower is something like 2,545 BTU of energy going up in heat. So if there is 20 horsepower in friction in a flat tappet, that is a lot of heat - like a 50,000 BTU, the heat energy of a big propane heater, and that seems implausible to me just off intuition.

Dulcich, have you ever ran a spintron for valvetrain? An interesting thing DieselGeek Scott told me that he observed watching one be operated is the engine seemed to warm up at essentially the same rate as on the dyno, and that is without the pistons installed or any fuel combustion. Basically he was real impressed with the amount of heat generated solely in the valvetrain in friction and spring flexing. Scott can correct me if I mis-heard him, but what are your thoughts or experiences on that?

[dieselgeek]

Dulcich, have you ever ran a spintron for valvetrain? An interesting thing DieselGeek Scott told me that he observed watching one be operated is the engine seemed to warm up at essentially the same rate as on the dyno, and that is without the pistons installed or any fuel combustion. Basically he was real impressed with the amount of heat generated solely in the valvetrain in friction and spring flexing. Scott can correct me if I mis-heard him, but what are your thoughts or experiences on that?

Oil temps on the Barton SS Hemi engine I saw being spinned, went up to 230+ in a matter of maybe 5 minutes of runtime on that thing. It even sounded like an engine running - with no pistons installed, sounded just like a dyno run.

[dulcich]

Oil temps on the Barton SS Hemi engine I saw being spinned, went up to 230+ in a matter of maybe 5 minutes of runtime on that thing. It even sounded like an engine running - with no pistons installed, sounded just like a dyno run.

I will not deny that lots of heat is generated. Like I stated earlier, I have never quantified it. In my youth I built an air compressor pump from a 215 Olds run by a huge electric motor, no combustion but converted from four cycle to compress every upstroke. It generated enough heat to need the addition of a full cooling system, so I know what you are talking about. I often hear the 20hp number in friction reduction in a roller versus a flat tappet cam. 50,000 btu... huh, seems like a lot of heat to me. However, I've never seen any hard data.
-dulcich

[Caveman Tony]

What do you think the longevity of a ceramic faced flat-tappet lifter would be in a street motor?

I'd have to WAG that those would be at least close in price to a roller lifter, if not more.

[Cyclone03]

What do you think the longevity of a ceramic faced flat-tappet lifter would be in a street motor?

I'd have to WAG that those would be at least close in price to a roller lifter, if not more.

I think Shoebecks(spl) are about $900 per set

[dave storlien]

Hello everyone
Was just informed about this post, kinda a day late and a dollar short I guess. But Steve thanks for your kind words. And I,m happy that I do get people thinking. An open mind is a terrible thing to waste. One thing that Steve did not mention is how I want to thank Demia Elgin and Allen Lockheed for all the knowledge that was passed on to me.