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I'm curious. If you convert from hydraulic flat tappets to hydraulic rollers on a moderate cam and go with full roller rockers, roughly, how much hp can you expect to pick up?
 

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Race it, Don't rice it!
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Not enough to matter for most guys. Barely measurable on a typical dyno kinda thing. Maybe on sophisticated A-B-A testing with an emphasis on controlling variables.
The advantage comes from the lobe profiles you can get with a Roller vrs the limitations of a FT
 

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I recall that when GM when to roller cams in the SBC, they claimed that the switch resulted in 15 horsepower. Their goal was to build emissions compliant engines that would last 50,000 miles, so not really the same thing as the custom engine builder goals.
 

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When the EPA reduced lead in gasoline following the Federal Clean Air Act in 1972, automakers reduced valve spring pressures and used hardened valve seat inserts in 1973. Automakers finally went to roller cams in 1991 when the EPA eliminted lead in gasoline.

Use “for off road use only” leaded fuel such as VP C12, and you can still use bone crushing valve spring pressure and solid flat tappet camshafts with Valvoline VR1 “Off Road” motor oil.

Be advised, it can be up to a $10,000 fine if you are caught using leaded racing fuel in a licensed vehicle capable of being driven on the street. I buy VP C12 108 octane leaded racing fuel in a five gallon can and pour it in the tank when I fill up with fifteen gallons of Mobil 91 octane premium. That produces about 100 octane fuel mixture with a some lead in it.
 

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I'm curious. If you convert from hydraulic flat tappets to hydraulic rollers on a moderate cam and go with full roller rockers, roughly, how much hp can you expect to pick up?
The cam timing has much more influence on power and torque than roller anything be that lifters or rockers where all other things are equal.

Roller lifters started to come about in the middish 1980's as a result of the growing elimination of zinc phosphate extreme pressure lubricant from engine oil because it when traveling with blow-by that is reinjested via the PVC and with oil pulled around the rings to contaminate the burn also contaminates the catalytic converter. Since there still is no viable long lasting alternative engine oil EP additive some 40 years later the decision was made back in the 80's to go to roller cams to eliminate the known wear issues that exist without ZDDP type additives. Lifespan had everything to do with this not increased power through friction reduction. If my memory hasn't failed me it was Ford that introduced the configuration we see from then to all other domestic cam in block engines through today. Everybody had a version of the system by the end of that decade on some engine in their line up. GM belatedly closed the gap for all their V8's by using these on the L30 and L31 truck engines as of 1996 production but you can find these cam's in passenger car engines since 1986 or 87 with sometimes appearing in trucks, but usually those engines include the basis provisions in the castings which can range from a raw casting of the provision being present to finished but unused.

The roller cam also allows recontouring the cam lobes to gain better engine performance while using lower octane unleaded fuel. This is accomplished be reducing the ramp degrees which for a given .050 inch duration results in more useful open time at the valve while reducing reverse pumping losses from the late closing intake languishing on a long lazy ramp. This increases effect trapped cylinder pressure which can be used to extract more power from lower octane fuel than old fashion long ramp cam's as they need a much higher compression ratio to compensate for the late closing intake, the long ramps necessary to lower the loads between lifter and lobe, these always being a problem with flat tappet cam's as far back in high speed gas engines as one can research and still build a cost effective production cam that doesn't need special surface hardening treatments like Parkerizing.

The same or similar things can be said for roller rockers, claims made for increased power for equal ratios are highly suspect. The advantage is cooler running at the trunion compared to a ball and socket combined with better wear with a roller tip than sliding shoe design. For a street engine living out its life mostly around 2000 RPM the ball and socket with sliding shoe will run for hundred thousand miles with no problem. Feed that same set up with 6000 crank RPMs a few times and combine it with a high lift cam and stiff springs and that system quickly and litterly goes up in smoke.

From a racers standpoint not all of this stuff is as much about making power as it is still making power when the checkered flag waves. DNF's don't make winners let alone garner any points.

Bogie
 

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Parasitic losses are more about the accumulation of a bunch of changes as opposed to just one.

Thin piston rings, back cut rings, low tension oil scrapers, roller rockers, roller cam, roller cam bearings, narrow bearings, low viscosity oil, low pressure oil pump, coatings. All are to reduce drag in the engine. On their own the gains are very small and even all together the gains are probably less than 15-20hp but in racing that 5% is the difference between 1st and not 1st.
 

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Low friction coatings have come a long way in the last 10 years. Parts that were thought to be exotic are becoming mainstream with coatings added to reduce uneven thermal transfer and friction of contact rotating parts and non contact rotating parts where sledge can stick to these parts.

It is a rpm game. If your going to run the engine into the 6000-8000 range then coatings and roller parts will make a difference.

If your just building a street engine that runs in the 2000-2500 range then a roller cam is not needed if you set up the engine properly.

A engine that revs slow and reaches peak torque low will in a majority of cases last longer. Less frictional wear, less stress, less chance for uneven lubrication, less impact by rotational weight items like heavy flywheels/driveshafts, fewer injector pulses, less impact by accessories, and on and on.

If you want to build the engine to run in front of a 2 speed for constant passes then fine roller parts will help.

If your just building a engine for the street that will not get over 3000 much a roller is generally not needed. You will need to run higher zinc oil which is not that bad but in the long run the cost difference of that zinc oil will make up for the difference in price in a street engine.

The biggest benefit of a roller on a low rpm engine is serviceability. A flat will GENERALLY require more adjustment then a roller.

Lower serviceability, coupled with the long term(cheaper oil) savings makes a roller a no brainier in many situations. The upfront cost is higher and if the engine is for short term use flat may be a better choice in something that is a low rpm torque beast like a 350 stroked to 400+ kind of deal.

As far as friction goes it is like czar said it is a combination of things to make a difference.
 

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I recall once when I was young pouring some Problend into my 442 at idle--it started smoking like a steam engine and the idle picked up a little, probably from some combustible solvent in the stuff. I never did it again.
 

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Castor oil, the only problems are it needs to be changed after every run of the engine and you can't breath the exhaust unless you've had a bottle of brandy. Other than that it really brings the internal friction down tell it cools and jells, but by then you're either in the outhouse or drunk, sometimes both.

Bogie
 

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Castor oil, the only problems are it needs to be changed after every run of the engine and you can't breath the exhaust unless you've had a bottle of brandy. Other than that it really brings the internal friction down tell it cools and jells, but by then you're either in the outhouse or drunk, sometimes both.

Bogie
Somewhat of a 'pick your poison' ehh? :thumbup:
 
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