[Skip Fix]

In looking at several of the cam specs used including the Kaase Pontiac, looks like 259-low 260s @ 0.050 on the intake with ALOT of lift is what most guys are using. I guess maybe because testing stops at 6500?? Wonder if the rest of us should be looking at smaller duration,higher lift cams.

[Tom Vaught]

One of the smartest Cam guys I ever met (Don Hubbard) wrote the the duration of the cam is purely based on the rpm of the engine unless you have a really bad port and are trying to "Crutch" the thing.

His specs for a 6500 rpm engine are right in the 255-265 @ .050 range. He has said that high lift is always a good thing if the rest of the system is designed for that lift.

Tom V.

[Steve C.]

Some tid bits from David Vizard concerning VALVE LIFT:

"A 2-valve cylinder head typically continues to flow more air up to lift values equal to as much as 0.35-0.4 times the valve diameter. The reason for this is that there is a flow pattern transition period that takes place at a lift value of about 0.25 of the valve's diameter. When this point is passed, if the port has been modified to support flow in this lift region, the valve efficiency actually starts to increase. This is the reason why a 2-valve engine responds to high lift." "If you want to build a street motor with the most power without a sacrifice of idle and low speed qualities, then lift is the most important factor to maximize, not duration. The best street cams are those that seek to maximize lift while only adding a minimal amount of duration."

Bottom line, the engine wants all the lift it can and thrives on it so run as much as mechanically achievable or prohibitive because of cost limitations, such as in a solid roller cam.

[J.C.you]

the way i understand it is, if you are limited on valve diameter/bore size for a combo that wants it, you should compensate by more lift.........

i believe the pontiac crowd has used too little lift, especially in the bigger cube/400cfm head combos, and should catch up to brand x in cam lifts that are used. maybe like getting over the RA IV and Roades lifters....... for example. hehe...

[Steve C.]

.4765 lobe lift with 1.7 rockers for .810 lift sounds fun. Ultradyne used that lobe for 280-296 degrees cams.

[J.C.you]

.57 with 1.75s sounds funner.....he he....

[Rocky Rotella]

Skip, it’s funny you brought this up because I read that article tonight and notice the same thing! That really isn’t a lot of duration for that large of an engine, especially when you consider that it’s a solid roller too. But DAMN that’s a ton of lift!

Tom V.’s post made me think about a conversation I had with Nunzi about cam duration and lift a while back. He said he has found that good flowing heads with strong low lift numbers and high port velocity can produce a substantial amount of power without excessive amounts of duration. He said a highly efficient port can fill a cylinder with less duration if the valve is lifted high enough, which lets the engine make broad power that peaks at a lower rpm.

Nunzi said that in many instances the excessive amounts of duration we see in a typical race motor is because of a lazy intake port. And that the builder has to use duration to fill the cylinder, which then pushes peak power to a higher rpm, shifting everything upward. He did say that the moderate duration/super high lift cams are usually too radical for a engine that sees lots of street use though. The valvetrain components required to accommodate these types of lift and stress is too costly and unpractical for a street engine.

JC, it’s obvious who your shot’s intended target is. And I am not here to defend him as his wagon says enough for him. But his approach sure sounds like what was stated above. I know he has posted on more than one occasion (and I know it’s in his book) that with an efficient intake port and moderate lift a street engine doesn’t need a ton of duration to make strong power. This translates into lesser amounts of duration, and the ability to run more stock type parts. If you add roughly 10 percent to his 474ci engine and 234 degrees cam that gets shifted at 5,500 rpm, you’ll come up with numbers similar to those of Kaase’s engine. That engine has heads with much more flow and over .800 inch lift to make the huge numbers. And it has to get it all done between 2500 and 6,500 rpm!

[J.C.you]

Rocky, you are reading way more into the silly example than was meant.

I mentioned no names and had no one in mind that runs a pontiac. I too have ran RA IV cams and Roades lifters many years ago.

All i was saying is the pontiac crowd should be looking at the technology brand x is using with the new, higher flowing heads available for a poncho.

also more duration in the right places will increase port velocity ........

[Rocky Rotella]

I know you didn't name names, that's why I didn't either. I truly wasn't arguing with you, but you know that anyone who reads that post will assume that you're talking about Jim Hand. I should probably also point out that only the first sentence was directed to you, the rest of the paragraph was just general speak.

I guess the point of the last paragraph was that Jim's theories and his wagon seem to come under fire all too often. But when we get right down to it, we see how Jim's theories apply to Kaase's winning combination. They're just scaled down. Funny how it all works, huh?!

[JSAauto]

Originally Posted by J.C. you

All i was saying is the pontiac crowd should be looking at the technology brand x is using with the new, higher flowing heads available for a poncho.

Brand X?? Now who would that be??

Back in the middle eighties, I had a friend work over some 48's I had. We cast iron welded the spark plug holes and aimed them at the exhaust valves, welded and reprofiled the chambers, had pistons made to match the chambers, raised the runners, moved rocker studs over, and started using very high lift cams all when Pete McCarthy was saying..... "It's not a Chevy.... you can't build it like a Chevy!! Haha!!

Back then the guy I sold them to made 600 hp and 600 ft lbs of torque with a mild 455. Took a Nash/Warrior intake and increased the plenum area by a good 9 square inches. Now all this stuff is common place with the Ponchos.

Take a look at the Pro Stockers. Over 1" lift and 120 degree int/exh lobe centers. Ever wonder how those engines idle at 1200 RPM with that lift??

Interesting stuff that inertia supercharging.

[J.C.you]

[QUOTE=JSAauto]Brand X?? Now who would that be??

"It's not a Chevy.... you can't build it like a Chevy!!
-------------------------------------------------------------------------

there you guys go again, reading a brand or person into my posts......

JS, i was actually refering to all brand x combos, not just the chebby.......

if you really want to look at current tech and the BUCS that will be sunk into racing in the next years, it will be across the pond, (Toyota/Honda) not with US automakers..... sorry to see the day, i mite add......

[J.C.you]

Originally Posted by Rocky Rotella

I know you didn't name names, that's why I didn't either. I truly wasn't arguing with you, but you know that anyone who reads that post will assume that you're talking about Jim Hand. I should probably also point out that only the first sentence was directed to you, the rest of the paragraph was just general speak.

I guess the point of the last paragraph was that Jim's theories and his wagon seem to come under fire all too often. But when we get right down to it, we see how Jim's theories apply to Kaase's winning combination. They're just scaled down. Funny how it all works, huh?!

-------------------------------------------------------------------------
What i was really talking about was, when the poncho crowd exceeds the 2hp per cube on a regular basis......

Many are stuck on the midset of, the only way a poncho will run is, put in the RA IV and roades lifters......... Not saying that is bad, but it is time to move past this way of thinking.

If one wants to build a nice low rpm motor, there is ample info for the pontiac crowd out there, to do just that.

When the 2+hp per cube is accomplished, that is something TO take note of, as you will be getting into the other brands territory........

[Skip Fix]

Tom, I've always thought the duration is one of the most important factors for rpm range. But as you said we've used bigger cams to make up for our ineffecient intake ports. I'm sorry guys a stock 215 cfm head feeding a 455 is anywhere from effecient for a race motor, neither is a ported 260 cfm head feeding a 474+ motor. We've debated the head issue a zillion times this is geared towards cam design in the race section here, not a daily driver to run fast.

My point was similar to what JC said, ALL brand X makes in the Engine Masters highlighted so far used this similar cam design thoughts. Obviously our D ports length valves with a 1.7 installed height it would be tough to get these lifts, shoot even E heads 1.800. The longer valve lengths on other brand X heads and including the Pontiac Tiger and new KRE head make this a little easier(and they are still Pontiac heads). Shoot Lynn and the Pontiac iron head Super Stockers are using really high lift and higher rpms in a 455!! Something many say shouldn't be done also, but they are looking at new technology to push the limits of the orignal designs.

Maybe as we get more effecient ports we need to rethink what cam specs we are using and look at higher lift shorter duration cams.I know my last solid roller motor had small lift(.556 1.5s) and 259/264@ 0.050 and still pulled 12" vacuum @ 900-1000 idle, I used lift limitation to limit the Hp for that combination for drivetrain issues.


I'll agree also with him in alot thinking our Pontiacs respond "differently" than all brand Xs. All the different brand Xs DON'T have all similar parameters also, they are as different as our Pontiacs are from each other, yet used similar plans, including the Kaase Pontiac.All of these motors have ports huge by current Pontiac thinking and they made gobs of torque at low rpm also not just a "high rpm motor with big heads" and was done at 6500. The Kaase motor included, not a 8000 rpm motor. Our Pontiacs really aren't that different.

If we don't look at what new technology is doing and looking "outside the box" of things to try for our Pontiacs, we'll never go faster. And there are more numbers of Brand Xs to look at what is being tried to see what works. We're even using some of that technology for those fast 40 year old iron heads to flow better by using flowbenches to port them, otherwise we'd be guessing on how it looks. We'd still be using cast rods, heavy TRW pistons and strictly factory cams, no UDs,XEs or Bullets and running in the 12s.

These new technologies are making it easy for Pontiac parts to be made using them. Eagle/SCAT, etc rods, custom light pistons. Look at the KRE D port head and it's chamber design. Look at the Tiger and High Port flow numbers and chambers. All more effecient.

So beside the Super Stockers and Kaase anyone trying a large lift smaller duration cam in a race motor?

[tempest455]

Anyone notice the RPM of the HP peak of the Kaase motor? With a 400+ CFM head yet!

[Steve C.]

I noticed and was pleased. I'm doing a street 505 and want to keep peak power at or below 6000 rpm.

Kaase's worked out good for the requirements of power from 2,500 to 6,500 rpm. HPP article indicates he peaked at 6,200 rpm.

420 plus cfm heads and I presume a 300+ cc intake runner volume (I didn't see it published). And with a Victor intake. Specs indicated the cam was 261/268 at .050

[Jim Hand]

Skip,
The Engine Masters Challenge is not a contest to build race engines. Instead, it is a contest to design and build street/strip engines. Scot Parkhurst, then of Popular Hot Rodding, came up with the concept of building engines suitable for both street and strip use. He decided to require power measurement to begin down in the street driving RPM range. While it has varied slightly in several of the contests, this year it was total power from 2500 to 6500.

Obviously, a race engine designed to launch at 6000 and shift at 8000+ is not going to be a very good street engine. But by requiring the builders to start the power at 2500, a different approach is needed. The cam is a compromise – it has to develop decent power at 2500, yet along with the rest of the engine, sustain good power to the upper limit of 6500. I have no doubt that all contestants could have made considerably more peak HP, and at higher RPM, but in so doing would have lost too much low end power and jeopardize any change of winning the contest.

And that was what Rocky meant in reference to my engine/car. I have built my engine also to make most total power, except within a lower RPM range (1500-6000). And obviously I don’t have the development time, testing, quality parts, and design effort in it as do the competitors in the challenge. But the concept is the same – build good power at low RPM for decent street use, yet enough power on top to be competitive at the track. Will post our drag strip times from a week ago.

I understand this is the Race section, and we street guys are not supposed to be on while you racers discuss the real engines! But I suspect that some of the “race” and street/strip engines would benefit from a lower RPM cam assuming adequate traction is available!

I have always advocated using as much valve lift as is feasible with the engine in question. And have also attempted to explain the benefits of optimum compression, just as all contestants used for most total power. And this year, CR will be limited to more closely relate to what is practical on the street, in an attempt to bring it back closer to the original street use concept.

My book discusses many of the ideas discussed on this Topic. However, they are not highlighted or identified as “Speed Tricks of the Week”. For example, on page 38, it states:
“The duration of the intake event is important in establishing the RPM operating range of the engine.”

And this on page 42: “Added valve lift generally improves midrange torque with stock heads. With properly ported heads, torque is added through the mid and upper RPM range, We want the valves to open as rapidly as possible in order to quickly reach the optimum port flow points.” Sounds familiar doesn’t it? And the power chart on page 45 suggest why moderate cams have to be used to remain competitive with wide power range engines.

A suggestion for you folks that own and operate race cars of any type – probably 95% of the readers don’t have race cars. But they do want to run harder. When serious race stuff is discussed, even though it is in this section, qualify it as more appropriate for real race engines. That would save a lot of confusion and arguments.

Here are the four runs we made with our 4050# wagon, with 3.31 gear, 92 octane pump gas, quiet full exhaust system, DOT tires, “non-efficient” 473 with “only” 265 cfm flow, and “too small” intake ports of about 170cc, Q Jet, RPM, Bullet cam of 234/244, 1.72 rockers, and the new Rhoads V-Max lifters.


Note especially the 1/8 mile speeds and Et’s and then realize the 4050# weight and the 3.31 gear - Car 729.
Jim Hand

[screamingchief]

So beside the Super Stockers and Kaase anyone trying a large lift smaller duration cam in a race motor?

I just bought a "street" solid roller on these boards a while back from Erik W. that kinda fits that description,though the lift is'nt quite .800" big.

I believe at some point somewhere he said it came from the late Bob Maxey's estate.

It is a smaller duration/relatively high lift cam if you asked me,duration @ .050" is 248/252,and it's ground with the .406" lobes which give appx. .650" net lift with 1.65 rockers.

Seemed like a fair amount of lift for me to work with...

So I suppose if one were inclined to use it with 1.8 ratio rocker or such it might be considered really high lift for it's duration.(.710" or so net lift)

I plan on using it in another 400 that'll eventually replace the current 406 solid lifter motor I'm using for my race car till I get that engine built,and the current motor will be relegated to "back-up" duty then likely.

I probably build the roller motor with max ported D-ports to begin with,then add some better flowing aluminum heads later if the motor does'nt meet my expectations with the D-ports.

Should be interesting though,and I expect I'll learn a thing or two from doing so,least I would hope I do.

Anyhow,I guess this is'nt quite the extreme ya'll are discussing here,but to me,when I saw the specs I could'nt help but think it was a lotta lift for a "street" cam with relatively short .050 duration numbers...

I liked that,and thought,"now that would be interesting to try out",hope it works well in the combo I'll be building for it.

Funny thing is the solid cam I'll be using in the current motor has more duration (256/260 @ .050"),and quite a bit less lift,(.360"/.365" lobe lift to be precise).

Will be interesting to see which works better.

Oh well,I digress,carry on here...

[Rocky Rotella]

Originally Posted by Skip Fix

I'm sorry guys a stock 215 cfm head feeding a 455 is anywhere from effecient for a race motor, neither is a ported 260 cfm head feeding a 474+ motor.

Skip, I agree with you, there is no doubt that stock heads are a limiting factor. But you don't always need huge flow numbers to make large dyno numbers either. As we all know, actual head flow is only a portion of the equation.

Just today I had a conversation with Nunzi and this topic came up. He told me in the past and then reconfirmed it today, several years ago his own race engine made 760hp at 6700 rpm with a 446ci and ported RAIV heads. However, intake port volume was around 205cc and flowed 280 cfm at max lift! He said the engine would have made 800hp if he would have spun it to 7000-7200 rpm, but because he set 6700 as the self-imposed redline, he saw no need to go higher. I'll have to call him tomorrow and ask what it ran in the car, but I do believe it was in the 8 to 9 second range.

[Steve C.]

I have a hard time with a claim of 280 cfm / 205 cc runner volume head making 800 hp!

(more of a question though, than any dispute)

I'm going to assume the tone or direction here is on 500-inch or larger combinations.

[Rocky Rotella]

Steve, Nunzi's told me numerous times that the cylidner head is only part of the total equation. He has also spoke of the 800 hp motor on several occasions, and that he has dyno sheets to prove it. I know that he's got a Nostalgia S/S 421-SD with #980 heads ported to 280-290 that runs 120+ in a 61 Ventura, and his own '62 421-SD Catalina runs with #980 heads runs around 126 mph. His RAV-powered AF/X '63 Tempest ran 140 mph in the 1/4 too.

I certainly can't argue with him, I can only repeat what he's told me. But I still believe him.