RB Cam Performing Right?

[lewtot184]

No.
The 231 degrees is the Mopar Performance BS of multiplying the advertised number by 0.85. The 221 degrees is the measured 0.050" duration of the 272 cam.

My 272 measured 223@.050", but seat timing was 277 at .006" in the 440 i ran in my r/ t. I think .85 number is ridiculous and is a marketing scam. I don't think a flat tappet cam can survive a real .85.

 

[gtxrt]

ok 272x.82=223. so his old 484 cam had about 233 duration at .050. 241x.82=233. about one size bigger than the 228 in there now. the big advantage of the 484 was the tight 108 LSA that even Chrysler knew back then to go for a tight LSA. what hurts is its low lift.

 

[dvw]

? I think the cam is:
112 LSA,
108 ICL

You are correct, I misread. I like the 112 much better for manifolds.
Doug

 

[lewtot184]

ok 272x.82=223. so his old 484 cam had about 233 duration at .050. 241x.82=233. about one size bigger than the 228 in there now. the big advantage of the 484 was the tight 108 LSA that even Chrysler knew back then to go for a tight LSA. what hurts is its low lift.

The 284/.484 i measured was 286@.006", 236@.050", 146@.200". I think they're racer brown ssh25 clones.

 

[gtxrt]

You are correct, I misread. I like the 112 much better for manifolds.
Doug

never seen a Dyno tests about LSA and exhaust manifolds.there are tests with a split duration with more exhaust duration but never LSA tests. or are just saying that you like it better.

 

[dvw]

never seen a Dyno tests about LSA and exhaust manifolds.there are tests with a split duration with more exhaust duration but never LSA tests. or are just saying that you like it better.

Andy F did a bunch of tests that liked the wider LCA with manifolds. I believe if you ask Dwayne about pure stocks he will agree.
Doug

 

[gtxrt]

470 HP and 520 TQ wouldn't be bad.

I have to re-think that. like pr heads said your in the ball park. his engine with header=482-528 then minus at least 25 HP and 30 TQ would be about 457 HP and 498 TQ without headers. yours is making 450 HP and 490 TQ very close. I know you have a bigger cam but with exhaust manifolds your not getting the full benefit of the bigger cam. the bigger the cam the more headers help. 460 HP and 500 TQ wouldn't be too bad. that 274 comp cam makes good power even if it is about one size smaller with more vacuum too. all dyno meters will give different numbers too.

 

[Road Grabber]

I have to re-think that. like pr heads said your in the ball park. his engine with header=482-528 then minus at least 25 HP and 30 TQ would be about 457 HP and 498 TQ without headers. yours is making 450 HP and 490 TQ very close. I know you have a bigger cam but with exhaust manifolds your not getting the full benefit of the bigger cam. the bigger the cam the more headers help. 460 HP and 500 TQ wouldn't be too bad. that 274 comp cam makes good power even if it is about one size smaller with more vacuum too. all dyno meters will give different numbers too.

Thanks for that info and calculated estimate. I did request future dyno testing with headers and manifolds.

If the numbers don’t impress me and I have to install headers to justify the build I would be interested in knowing about a higher lift cam to use with headers that maximizes the head flow and is streetable.

Also it will be interesting to see improvement if any with the right custom fit pushrods installed that aren’t flexing like the weaker 5/16 rods that bent. One set completely failed and at least half were bent.

 

[1KoolBee]

Overlap is your enemy on manifold motors. Some builders have found that anything hotter than the MP .528 solid cam is counterproductive on engines with factory exhaust manifolds. Interestingly, the factory big block solid lifter cams from Chevrolet had similar specs to the MP .528. So swap cams or get headers, headers obviously will make more power.

 

[lewtot184]

I think chevy used 114lsa on their 375hp and 425hp rat motors plus the solid tappet. My personal rule of thumb is 60 degrees of overlap as a limit and less might be better.

 

[Hemirunner]

Interesting situation. It seems to be a struggle between wanting more power and keeping street manners. It’s the age old question of what is streetable?
My perspective is way different than most on here for sure, but my curiosity has me inquiring as to how you came to arrive at this combination?
My other questions would be ….
Are we really set on running manifolds and that teeny tiny little hydraulic roller? Or actually taking advantage of those good heads?
What gear are you planning on paring with that engine?
What’s the rest of the combo and what kind of driving do you intend to do with the car?

I’m the last one to advise on how to make huge power through manifolds as I think they have 3 places they belong- Restorations, FAST and factory stock racing and bolted to a turbocharger in low buck builds, but I’d rethink the manifolds and the cam.

 

[dodgeboy440]

Andy F did a bunch of tests that liked the wider LCA with manifolds. I believe if you ask Dwayne about pure stocks he will agree.
Doug

Makes perfect sense !

OEM manifolds have more restrictions, hence
Slower to exhale . Permitting the engine to balance it’s breathing with its heart , the camshaft!

Mopar2ya

John

 

[Road Grabber]

I get it. It’s typical to find things out when you venture into personal uncharted waters when you leave stock high performance using aftermarket components. Using the aluminum heads caused a chain reaction.

How did I come up with this cam?

During research I heard Howard’s cams are Mopar friendly with lifter bore diameters and other stuff. I called Howard’s and asked for a cam that would help maximize the potential of the Trickflow heads yet be able to function with power brakes on the street. It was their suggestion.

Looking at what others were doing

There’s a lot of YouTube videos on 600 horsepower with headers but none with manifolds. Only Nicks Garage with stock engines using manifolds on dynos.
I don’t recall any builders on other videos giving up the cam for their builds. Holding back maybe to make you want to hire them to build your engine. Whatever bottom line I took a suggestion from Howard’s hoping to make a sizable improvement and lower the risk of detonation with aluminum heads. High power/torque as a bonus. But not where I left off. That confirmation still to come.

The car has a 3.54 Dana four speed. It won’t race on the track. I had a friend who chased huge power and it led to a lot of suspension issues and frame strengthening. It’s a six pack RT and I don’t want to convert into a 1/4 mile monster with constant costly upgrades. So it will be a driver with some fooling around.

I would put headers on the engine to capture horsepower if that’s what needs to be done but I don’t see the point of buying TTI headers without changing the cam too. I know I won’t buy crap headers. Been there done that when I was 17 and didn’t care about noise, burn wires and heat under the hood.

Next question. If I do decide to grab the horsepower ring like I see RB engines are doing like with Top end kits from Trickflow is that an engine that can be driven on the street and one that doesn’t eat itself up in a few years because of more potential wear from heavy valve spring pressure, valve guides wearing out ( smoke out the tailpipe looks like crap) and another refresh just down the road?

That kind of first hand feedback would be useful because you don’t hear about how long the high horsepower engines are lasting. Are the 600 hp engines lasting long? I know my 440 six pack with the 284/484 cam was in the car over 30 years before I pulled it. Ran great except detonation with cast heads.

Choosing a cam is very difficult choice. The vendors want to sell their products making huge gains but you don’t hear much about applications and durability. I get how the cam needs the right combination.


I might hear back in a week or two about the new dyno tests. In the meantime any thoughts about a better option if you have one be my guest.

Thanks

 

[Hemirunner]

So.. if you’re chasing horsepower, the question becomes, what’s the number?

I think reliability can be built into any power level, but increased cost and other changes to the car are then required as you’ve noted.

Have you ridden in, or driven an old mopar with 500ft/lbs of torque? I think it would be an eye opener, especially with the 3.54 and a four speed.

Once you have the end results of dyno testing with the replacement pushrods, you can make a decision as to the path forward. You might actually have what you’re really looking for but the numbers just don’t align with what you think you want.

 

[496 polara]

If you go headers the 1 7/8 would be the largest I would run with your setup. 1 3/4 would only give up a few hp up top as well.

Get the motor back together and run it with no issues and rhen decide if you want headers before you go changing cams.
Headers on a well running motor may give you all you need for a hot steel car. What you want may be a different animal.

If you aren't going to track it then build for torque. That is what moves a 4000lb car and does good burnouts.

You can end up chasing your tail with a number. Not to mention your wallet with dyno time.
If you decide to put another cam in it give @PRHeads a call. Especially with manifolds.

 

[Road Grabber]

The reliability part is what I haven’t seen or heard discussed using 500-600 hp motors. I would certainly be willing to take any hp gained if it meant I could still drive on the street and have power brakes.
I know it would be an eye opener for sure jumping into that category. I haven’t had a conversation with anyone who owns a car like that on the street as I haven’t been to the shows in years or seen a car with that hp at a car cruise.
Will it mean adding frame rails, does it mean going from 8mpg to 4mpg, power brakes? I’ve only seen the quest for huge hp dyno tests on YouTube. No user feedback. It does help.
Yes, the new dyno test with everything functional will be the next step. The builder actually did mention that the headers he feels should jump it quite a bit. But if he tells me not much of a change with 8-10 vacuum I would think that is not much different from a larger lift cam.
No decision till the dyno test. It would be interesting to hear from someone who installed the Top end Kit sold by Trickflow that they claim results in 600hp.

Thanks for shooting back.

 

[gtxrt]

you're hung up on HP and should be hung up on torque for the street. give me 465-475 HP and 550 TQ for the street. you keep saying larger lift cam and vacuum but more lift does not hurt vacuum. advertised duration effects vacuum and so does LSA not lift.

 

[496 polara]

I have the Trick Flow heads and a larger cam than in the Trick Flow kit in my 505. No power brakes mind you so I haven't checked vacuum. I also have 3.55 gears and it idles and putts around just fine,even with 2" headers and a single plane intake.

Even if you went up 10* on the cam I don't see power brakes being a problem. My old 465 had a 246/250 @ .050 cam and the power brakes were fine.

I think frame connectors are a great idea,even on a lower powered car. Everything flexes less so handling and steering turn in are improved.You can always do bolt ins if you want to return to stock later.

The more efficient the engine the less mpg will take a hit IMO. Driving style plays more into that than anything.

 

[BSB67]

I think chevy used 114lsa on their 375hp and 425hp rat motors plus the solid tappet. My personal rule of thumb is 60 degrees of overlap as a limit and less might be better.

My current cam has 48 degrees overlap and runs about the same or a bit better than the previous cam with 54 degrees overlap.

Overlap is your enemy on manifold motors. Some builders have found that anything hotter than the MP .528 solid cam is counterproductive on engines with factory exhaust manifolds. Interestingly, the factory big block solid lifter cams from Chevrolet had similar specs to the MP .528. So swap cams or get headers, headers obviously will make more power.

Andy F. made 550 hp with that cam with manifolds on his 470. Pretty small cam. Probably 0.500” net lift. Probably 230 -232 degrees duration at 0.050” when considering the 0.028” lash.

500 cu. In.
600 hp -ish
Manifolds
15” idle vacuum
Used a stock stall converter for years
3.23 gear
2 1/2” exhaust
15 years old
Drive it to work. Drove it to both Carlisle and Mopar Nats this year, with track time at both.

Probably not a 50,000 mile motor. With a couple changes, could be. But ask yourself this how: many miles do you really drive your car? You’ve had your car for 30 years. How many miles did you put on it? What does your next 30 years of driving look like?

All that said, based on your comments in this discussion, keep the cam, put headers on it, put it in the car, close the hood and forget about it. It won’t matter if I it makes 450 or 550 hp. You, nor anyone else will know.

If you want to stick with manifolds an explore a better cam, contact someone that has experience and does it for a living. Like PRH.

 

[Hemirunner]

I’m currently somewhere between 1200-1400 whp right now and it’ll drive anywhere, so my viewpoint is somewhat skewed, but it’s been on the road since 2020 with just basic maintenance. I don’t run power brakes, but it makes enough vacuum to do it. I currently get 10mpg on E85 with my Air Conditioner on so why would you get less on gas? Especially with that six pack.

Headers and a cam would probably put you where you want to be without sacrificing anything.