[Cliff R]

Tighter LSA and earlier closing intake will pull power down in the rpm range, narrow up the power, and it will NOT pull nearly as high in the rpm range as the 2802 cam. The 2802 wouldn't make much power past 5000rpms.

Folks quickly forget here that this is a 455 engine fed by heads with pretty conservative intake runner volume and cross section. These engines need at least 230 @ .050" to make power past 5000rpm's.

I've seen much larger cams not make power past 5000rpm's in 455 engine builds. This is DIRECT experience right from the dyno, not a dyno simulation or Google search trying to find an example someplace that agrees with my line of thinking.....FWIW.....Cliff

[pastry_chef]

Originally Posted by pmd400

How did you come up with is result? I figured if a summit 2802 cam could make power to 5000rpm than the straub cam should be able to as well.

Initially derived from many third party formulas.
I know some of the private tools that Chris has.
No guessing.

Like Chris. I've been obsessed with results for more than 20 years.
Studying combinations, dyno sheets across many brands.
I've learned more in the last 2 years than the previous 20.
The truth is out there, read and listen to the best.
Then finally prove it to yourself.

Some of the 'nature' may have been inherited from my Engineer father.
Both of us were to top of our class. Both won many awards academically and then professionally in career.

[pmd400]

Originally Posted by Formulabruce

All this and I'm not sure why it needs 2 carbs... seems over kill when you can get a Q-jet to run like fuel injection. I am betting the piston tops WILL carbon up fast on this build.

Iv got a couple of factory intakes, a Torker 2 and a few qjets that will require modification per cliffs book that Iv read cover to cover. The only reason I want to give he dual quads a go is because of the way they look. If they are terrible they will go. Why would the pistons carbon up. If it is set up progressively it will only be running on the primary of 1 600cfm carb 98% of the time. These carbs are currently running on a stock 72 low comp 350.

[Cliff R]

"Initially derived from many third party formulas.
I know some of the private tools that Chris has.
No guessing.

Like Chris. I've been obsessed with results for more than 20 years.
Studying combinations, dyno sheets across many brands.
I've learned more in the last 2 years than the previous 20.
The truth is out there, read and listen to the best.
Then finally prove it to yourself."

So you do NOT have any first hand or direct experience with actual cam testing in 455 engines.

I figured as much based on the continuing post full of miss-information and poor camshaft recommendations for these engines.

No amount of research makes up the lost ground for getting out from behind the key board and going out there and getting it done.

At some point no matter how smart one thinks that he is, or how much you think something is going to work, you've got to go out and get dirty and do your own testing.

Not trying to be super critical here or make any sort of personal attack, but a reality check is in order here......you really don't know that that Straub cam is going to make power to any particular rpm in this application. You really don't know if a 2802 cam will make peak power at or above 5000rpms either.

I have witnessed on the dyno scores of 455 engines make pull after pull with cams larger than those and NOT make peak power at or much past 5000rpm's. The absolute WORST of the bunch were camshafts with short seat timing events (advertised duration) and tight LSA's.

I have built 455's with a wide variety of camshafts, even back to back dyno'd samples with more head flow than we have here, more compression, and larger camshafts and have been disappointed that they didn't make peak power very high in the rpm range.

I've even moved the ICL all over the place to try to find out if they engine just didn't like the tighter LSA, or if doing so will help the situation. I've even back to back tested 3 different camshafts in the same 455 engine right on the dyno to see how they compared to each other. You can Google up that deal and probably aren't going to find anyone else who's done been there and done that.

Once again as it relates to this topic. The 455 is a HUGE engine, it has long stroke with heavy internals and fairly long connecting rods. The heads and intake system are somewhat restrictive for that much CID. By design they will try to throw all the power at you very early in the rpm range. So basically they are very good at torque production and excellent mid-range characteristics, but seriously lacking in upper mid-range and top end potential.

Despite the less than ideal design and parameters they are still EXCELLENT engines for powering heavy vehicles and they don't require a lot of gear or converter to get it done. In order to get the very best from one, we need to install a camshaft that will push some power up higher in the rpm range and spread out the power as well. Installing small cams on tight LSA's is going backwards here. This will pull power down in the rpm range, and improve VE and peak torque will be higher and occur earlier.

So these little camshaft basically make the 455 better at what it already does best, TONS of power early in the rpm range. As good as this sounds to some it quickly works against us as it spikes cylinder pressure much higher with improved cylinder filling. I've had PLENTY of 455 engines in here to tune where the compression ratio wasn't all that high but they still pinged like SLEDGEHAMMERS on pump gas because the cams were small and tight LSA.

I've put up threads on the subject, with actual results and plenty of accurate information on this, but folks continue to make poor camshaft choices for these engines, and listen to folks with little if any real experience with the Pontiac 455 engine, aside from what they have Google'd up researching the subject.....FWIW

As for two 4bbls to power this engine build, I see nothing wrong with that at all. Like every other engine out there they will need correctly dialed in exactly for the application. At that point they will work fine, and no reason there would be any negatives from using them.......Cliff

[pastry_chef]

Originally Posted by Cliff R

engines.

I figured as much based on the continuing post full of miss-information and poor camshaft recommendations for these engines.

No amount of research makes up the lost ground for getting out from behind the key board and going out there and getting it done.

At some point no matter how smart one thinks that he is, or how much you think something is going to work, you've got to go out and get dirty and do your own testing.

Not trying to be super critical here or make any sort of personal attack, but a reality check is in order here......you really don't know that that Straub cam is going to make power to any particular rpm in this application. You really don't know if a 2802 cam will make peak power at or above 5000rpms either.

I have witnessed on the dyno scores of 455 engines make pull after pull with cams larger than those and NOT make peak power at or much past 5000rpm's. The absolute WORST of the bunch were camshafts with short seat timing events (advertised duration) and tight LSA's.

Please post a valid dyno comparison between THE SAME LOBES with two different LSA's
We've seen a few of the invalid comparisons posted.

Contrary to what you might believe there are MANY others who have valve timing figured out. There is also no checkbox for "Pontiac" specific. FACT.

The ONLY results/ advice I took notice of was from those who have a long history of clients who set records and won championships. Yup, BIG TIME results!
Thousands of dyno tests.
With that said I was a skeptic for a while. I needed to evaluate the algorithms myself.

[Cliff R]

So it is true that ALL of your information is regurgitated from other sources, which I suspected from the very first post you ever put up on this subject.

Anyhow, NOBODY is going to have the exact same cam ground on different LSA's then spend days on the dyno making those sort of comparisons. That is a very unrealistic expectation considering the cost of doing that deal is over $500 per day plus the cost of the custom ground camshafts and time/labor required to do the work.

Instead I can tell you about scores of unsuccessful engine builds using a variety of very popular currently available camshafts and compare them to camshafts that made the grade.

The trend I'm seeing here is that the wider we go with LSA in Pontiac 455 street engine builds, the more we are rewarded with smoother idle quality, better street manners, and broad/flat power curve. This doesn't mean you can't make great power with tighter LSA's, but there are dozens of other factors involved with engine building that determine which cam will make the grade or not.

I will say this, absolutely and for sure the most complaints we get here to the shop from folks seeking help with their new engine builds and they absolutely HATE the results are those that have selected tight LSA camshafts such as the Thumper and Mutha-Thumper series. Most don't have nearly the compression for such cams either, so the piss-poor cam choice is further compromised by very low dynamic compression at idle and low rpm's. For the Pontiac 455 engines, those complaints are followed closely by folks who used the Comp XE262, 268 and 274 camshafts, with the guy screaming the hardest actually using a Comp XE256 in a 455 with 9.3 to 1 compression on the advice of his machine shop/engine builder.

As it relates to this thread, we built and dyno's a 455 with much better flowing Edelbrock round port heads, 10.4 to 1 compression, and Crower 60919 cam with Rhoads lifters and high ratio rockers. As big as the 60919 cam is, the engine made peak HP at 5100rpm's!

The numbers specifically were 505hp/551tq. Despite quitting a bit earlier than we had expected, that engine went into a 1971 Firebird and ran 11.50's at 118mph on it's first track outing! So it obviously made plenty of power over a broad rpm range to get good results.

So here we have folks telling us that considerably smaller camshafts will pull up to 5000rpm's or so with less head flow and intake runner cross section.....highly unlikely!......Cliff

[Steve C.]

"Anyhow, NOBODY is going to have the exact same cam ground on different LSA's then spend days on the dyno making those sort of comparisons. That is a very unrealistic expectation considering the cost of doing that deal is over $500 per day plus the cost of the custom ground camshafts and time/labor required to do the work."

Ture. But that's what needs to be done.



.

[Formulajones]

Originally Posted by Steve C.

"Anyhow, NOBODY is going to have the exact same cam ground on different LSA's then spend days on the dyno making those sort of comparisons. That is a very unrealistic expectation considering the cost of doing that deal is over $500 per day plus the cost of the custom ground camshafts and time/labor required to do the work."

Ture. But that's what needs to be done.



.

I agree Steve, if people are going to boast about wide LSA's being better, then that's exactly what needs to be done.

I've talked to Crazy Dave (he doesn't live far from me) on several occasions about his camshaft choices and using Chris Straub. I get the feeling Chris is pretty good and knows what he is doing based off the results I've seen. I'm glad PMD400 chose Chris Straub for his Pontiac engine (finally someone took a different route away from the norm) and very interested in seeing how the results turn out for him.

[Steve C.]

Then then we will argue over the amount of duration. Do we choose the Stump Puller or the Old Faithful !

As we know it can be done:

Camshaft Lobe Separation Angle Performance Test - 6 Degrees Of Separation
Does A Camshaft's Lobe Separation Angle Really Make A Performance Difference? We Hit The Dyno To Find Out.

http://www.superchevy.com/how-to/eng...formance-test/


.

[tom s]

As this is the street section performance to me is secondary to driveabilty with a high performance street engine.I have spent the last 20 plus years trying to find a balance of duration and LC with stick shift cars with engines from 366 CI to 455 CI and to me the tight centers are less friendly to wide.I could give a tinkers damn about 20-30 HP when I want to drive my cars as I will be doing in about 30 min to go to a pontiac car show.If HP numbers is the all important number than move it to the race section.Carry on.Tom

[Formulajones]

You're just getting old Tom

Plenty of big power street builds around my neighborhood. I see nothing wrong with the Pontiac people trying to keep up

[Formulajones]

Originally Posted by Steve C.

Then then we will argue over the amount of duration. Do we choose the Stump Puller or the Old Faithful !

As we know it can be done:

Camshaft Lobe Separation Angle Performance Test - 6 Degrees Of Separation
Does A Camshaft's Lobe Separation Angle Really Make A Performance Difference? We Hit The Dyno To Find Out.

http://www.superchevy.com/how-to/eng...formance-test/


.

LOL yeah Steve that will come next.

I guess I just get tired of seeing the usual recommendations of the 068 or the 041, or the old faithful etc... Yeah they work well enough for most of the people here with stockish builds, but they certainly wouldn't be my first choice. I just find it nice that someone is stepping away from the norm to experiment a bit.

I'd like to see more people use something like a Straub design, or see Paul and Jeff put a custom grind together for one of their Pontiac builds, those guys can make some power over there. Next engine I have Paul do, I'm leaving the camshaft choice in there hands, then it's going on the dyno. No off the shelf stuff for me. When I know we can make it idle just as well, I'll gladly take the extra 30HP
That's just money in the bank considering what I'd have to spend to find 30HP anywhere else on the engine.

[ta man]

Originally Posted by tom s

As this is the street section performance to me is secondary to driveabilty with a high performance street engine.I have spent the last 20 plus years trying to find a balance of duration and LC with stick shift cars with engines from 366 CI to 455 CI and to me the tight centers are less friendly to wide.I could give a tinkers damn about 20-30 HP when I want to drive my cars as I will be doing in about 30 min to go to a pontiac car show.If HP numbers is the all important number than move it to the race section.Carry on.Tom

I don't really consider the OP build a high performance street engine.The induction and camshaft are a big mismatch.It will look great at the dairy queen with the dual carbs..but this isn't my cup of tea all flash and no go.Dual carbs and maxxed out at 4800rpm?A better camshaft choice would have provided more power and better overall street manners as well as a single carb.

[Steve C.]

Optimising- make the best or most effective use of (a situation, opportunity, or resource).

I have no issue in one trying to optimise every last few horsepower from a combination in conjunction with a camshaft selection if desired. Not much different than one pushing the envelope with the desire to run 10:1 compression instead of a safer 9.5:1 with iron heads. Both are after that little bit of difference in performance.


Next will come the 'argument' where will the testing be done.

If I could choose, my choice.....

Many of us have seen the dyno at work on Engine Masters videos comparing cams and testing headers. They do it through the help of Steve Brule of Westech Performance Group. Much more than convenient in location for the magazines, their engine dyno facility is state of the art and one of the best in the nation. Reliable and consistent for back-to-back testing. Now that said, some will cry foul that they are the 'dyno of the stars' and the horsepower numbers are bloated ! Doesn't matter a bit for comparing. And besides some have suggested a certain Pontiac shop in Ohio is also known for generous hp numbers on their dyno


.

[Formulajones]

Originally Posted by Steve C.

And besides some have suggested a certain Pontiac shop in Ohio is also is known for generous hp numbers on their dyno


.

Yep, we have some experience with that as well, lol.

[Formulajones]

Originally Posted by Steve C.

Optimising- make the best or most effective use of (a situation, opportunity, or resource).

I have no issue in one trying to optimise every last few horsepower from a combination in conjunction with a camshaft selection if desired. Not much different than one pushing the envelope with the desire to run 10:1 compression instead of a safer 9.5:1 with iron heads. Both are after that little bit of difference in performance.


.

I agree 100%. Every die hard car guy I know is always looking for a little more, trying to improve on something. That's why we hog out these stock intakes, port the cylinder heads, push the compression ratio envelope etc.... A custom camshaft is no different, and one of the cheaper options to boot.

[Cliff R]

It would be a complete WASTE of time and funds to do a direct LSA test with camshafts.

We're smart enough at this point to know when we see an engine not making nearly the power expected, and the culprit is the camshaft, we simply replace it with something that is dyno, street and track tested that we absolutely know will work.

As mentioned in my first response to the subject, it would be a wasted effort to piss around with a tiny cam which in this case is poorly chosen for the application and simply move the lobes further apart or closer together to see what works best. It is NOT going to be very impressive no matter where you put it....IMHO.

What has me LMAO here with these conversations is that folks just want to create controversy vs helping a guy out. I could gear up and spend the time and funds to do an LSA test, them some guy with about as much experience with these things as I spent on crapper last week would want to disqualify the testing because I didn't pick a cam with enough duration right to start with, or like Steve mentioned didn't use the very best dyno facility, or that we didn't track test each cam to back up the results, etc, etc.

The only helpful comment made in the last dozen or so responses was from Tom S in post #50.

My experience concurs with that statement, for street engines, specifically 455's I've found wider LSA to be more user friendly, especially if you are yanking a lot of compression out of these engines and starting to look at cams big enough to make decent power.

If you are following the masses and limiting to 9.5 to 1 and installing a small/tight LSA cam to bring back all the lost power, then making optimum power on pump gas or having a really fast car was never among your goals for the project right to start with.

Hey it's OK though, because you can still sit there at the car shows and cruises with your chrome valve covers and shiny intake and carb(s) and tell stories of running into the 10's, and even show off some when you do a decent burn-out in a hard right hand turn leaving the event!.........Cliff

[Steve C.]

A fwiw, not long ago after a problem with a solid roller lifter and the need to replace the cam because of it I ordered the new cam from Bullet Racing the same except for the lobe separation. I went from a 110 to a 112. Personally I did not find the 110 a issue at all but did so because I knew at the time I was going to make the change to direct port fuel injection. That said, to my seat of the pants driving it only has a SLIGHTLY improved idle quality as expected and a tad bit different exhaust note to the car. Other than that I can tell no difference driving my car at slow speeds or a quick blast to 130 mph.


.

[Stan Weiss]

Originally Posted by Steve C.

"Anyhow, NOBODY is going to have the exact same cam ground on different LSA's then spend days on the dyno making those sort of comparisons. That is a very unrealistic expectation considering the cost of doing that deal is over $500 per day plus the cost of the custom ground camshafts and time/labor required to do the work."

Ture. But that's what needs to be done.



.

Steve,
Actually many years ago David Vizard worked with Harvey Crane and ran those and many different dyno test (1000's) using SBC engines. The results of those test was the original bases of David's COS Cam selection program.

Stan

[PDC]

I just clicked on the link to the article about your blue car. I have that issue and loved that article. I thought 'what a cool guy, it would be nice to meet him someday.' Little did I know I've been reading your posts for a couple of years now! Glad I finally put it together.