[Danspeed1]

I'll keep the top part of this short if you don't want to read a lot and want to help me pick a camshaft. At the bottom; I asked AI to pick a camshaft for my Pontiac project and this is what it came up with. Sounds pretty great to me, but how does it work in the real world?

1976 Pontiac Firebird (full weight)
Early 400 Block
RPM Industries 4.375 Crankshaft
.030 pistons (not ordered yet)
Scat BBC H Beam Connecting Rods
Speedmaster 72cc aluminum heads
Unknown Intake Manifold
Longtubes with free flowing exhaust
3.43 gears
4L60E (Yes "E")
3600 Yank Converter
10.5-11:1 Compression

93 Octane Pump Gas if I run a carb but we are considering Holley EFI so possible E85

Looking to turn 6000-7000rpm and street cruise, moderate to aggressive lope

----------------------------------------------------------------------------------------------------

Here's what AI had to say:
Got it! Since you’re specifically looking for a hydraulic roller or solid roller camshaft for your stroked 475ci Pontiac 400, let’s focus on cam options that will support the high RPM range you want (6000-7000 RPM) while maintaining the performance and reliability that a roller cam offers.

Key Considerations:
Hydraulic Roller vs. Solid Roller:

Hydraulic Roller Cams are great for street applications because they provide a smoother idle and less maintenance (no need for lash adjustments).

Solid Roller Cams are typically used for more aggressive, high-performance applications, offering better high RPM stability and power, but they require more maintenance, including lash adjustments.

Since you're aiming for 6000-7000 RPM, we’ll focus on cams that can handle that range and match well with your 475ci engine, high compression, and 93 octane fuel.

Camshaft Recommendations:
Hydraulic Roller Camshafts:
Comp Cams XR290HR

Intake Duration @ .050”: 248°

Exhaust Duration @ .050”: 254°

Lift: .525” intake, .550” exhaust

LSA: 110°

This is an aggressive hydraulic roller cam that will perform well in the 6000-7000 RPM range. It offers a nice blend of top-end power and streetability. It should work well with your engine combo, providing a great powerband with good low-end torque without being too extreme on pump gas.

Lunati Voodoo 60123

Intake Duration @ .050”: 248°

Exhaust Duration @ .050”: 254°

Lift: .525” intake, .550” exhaust

LSA: 110°

This is another solid option for a hydraulic roller, designed for high RPM and strong performance. It’s a good match for your 475ci engine and 3600 stall converter, offering strong top-end power while still being streetable on pump gas. This cam will provide solid throttle response and a good power curve.

Solid Roller Camshafts:
Comp Cams Solid Roller 292S

Intake Duration @ .050”: 248°

Exhaust Duration @ .050”: 254°

Lift: .650” intake, .670” exhaust

LSA: 110°

The 292S is a solid roller cam designed to provide aggressive top-end power and stability at high RPM. This cam would really shine in the 6000-7000 RPM range and will make serious power with your 475ci engine, though it will require more maintenance (lash adjustment) compared to a hydraulic roller. It’s a great choice for a high-performance build that prioritizes peak power.

Howards Cams Solid Roller 212695-10

Intake Duration @ .050”: 252°

Exhaust Duration @ .050”: 258°

Lift: .660” intake, .680” exhaust

LSA: 110°

This cam is designed for high-revving applications and would make excellent power in the 6000-7000 RPM range. It's aggressive and will be more suitable for serious performance applications, but as with all solid roller cams, it will require lash adjustments and attention to maintenance.

Lunati Solid Roller 60302

Intake Duration @ .050”: 254°

Exhaust Duration @ .050”: 260°

Lift: .650” intake, .670” exhaust

LSA: 110°

A solid roller cam with slightly more aggressive specs, this one will really help maximize the high-RPM performance of your 475ci engine. It’s ideal for the street/strip combination where top-end power is key. Expect excellent throttle response and power through the higher RPMs.

Key Features of Hydraulic Roller vs. Solid Roller:
Hydraulic Roller Cams like the Comp Cams XR290HR and Lunati Voodoo 60123 will give you good high-end power with a smooth idle, and the major benefit of reduced maintenance compared to solid roller cams. They are more street-friendly but still capable of reaching high RPMs with strong power output.

Solid Roller Cams like the Comp Cams 292S and Lunati 60302 are better for extreme performance, offering more aggressive power delivery and stability at higher RPMs. However, they require lash adjustment and are generally higher maintenance.

Final Thoughts:
For a more streetable, low-maintenance option, I recommend a hydraulic roller cam such as the Comp Cams XR290HR or Lunati Voodoo 60123. These options will deliver the high RPM power you're looking for, while also being easier to live with on the street.

If you're prioritizing maximum performance and don’t mind the additional maintenance of lash adjustment, go with a solid roller cam like the Comp Cams 292S or Lunati 60302. These will really help you reach your peak power goals in the 6000-7000 RPM range.

In either case, make sure your valve springs are up to the task of handling the cam's lift and RPM potential, and ensure that your entire valvetrain is properly set up for the cam you choose.


You said:
Can you calculate how much horsepower the Comp Cams XR290HR and Lunati Voodoo 60123 should make on a 400 pontiac block bored .030 over with a 4.375 stroke, 10.5 to 1 compression, using a set of 72cc speedmaster aluminum cylinder heads, and a stock intake, with a 1050 dominator carb and a free flowing exhaust

ChatGPT said:
To calculate the approximate horsepower for your Pontiac 400 block with the specified setup, we need to estimate the engine's airflow, volumetric efficiency (VE), and other factors that impact power production. Let's break down the components and key factors, then use a basic formula to estimate horsepower.

1. Engine Specifications:
Displacement: You've already mentioned the engine is stroked to 475ci.

Compression Ratio: 10.5:1

Cylinder Heads: 72cc Speedmaster aluminum heads (we'll assume they flow well, but not excessively).

Carburetor: 1050 CFM Dominator carb (large, high-flow carb ideal for high-power builds).

Exhaust: Free-flowing exhaust.

2. Components Overview:
Bore: 4.155 inches (standard Pontiac 400 bore) + 0.030” overbore = 4.185 inches.

Stroke: 4.375 inches.

Compression Ratio: 10.5:1.

Carburetor: 1050 CFM Dominator (should provide plenty of air/fuel for your build).

Heads: 72cc aluminum heads with good airflow (likely around 250-280 cfm @ .600 lift).

3. Basic Formula for Horsepower Estimation:
For a naturally aspirated engine, we can use a simple formula to estimate horsepower based on engine displacement and volumetric efficiency (VE):

Horsepower=Displacement*(ci)x RPM × VE
×
0.65
1
,
000
Horsepower=
1,000
Displacement*(ci)×RPM×VE×0.65
​

Where:

Displacement (ci): 475 cubic inches.

RPM: Peak power RPM. We will estimate around 6,500 RPM based on the cam profiles.

VE: Volumetric efficiency. Typically ranges from 75% for stock setups to 90-95% for high-performance engines.

0.65: A constant to account for the air/fuel ratio and efficiency.

Estimating Volumetric Efficiency (VE):
With your setup (large carb, free-flowing exhaust, decent aluminum heads), we can estimate a VE of 85% as a reasonable value for a performance engine.

Step-by-Step Calculation for Each Cam:
Comp Cams XR290HR Camshaft:

Displacement: 475ci

RPM: Estimated peak power around 6,500 RPM (based on the cam's characteristics).

VE: 85% (estimated).

Horsepower
=
475
×
6
,
500
×
0.85
×
0.65
1
,
000
Horsepower=
1,000
475×6,500×0.85×0.65
​

Horsepower
=
1
,
674
,
687.5
1
,
000
=
674.3
*horsepower
Horsepower=
1,000
1,674,687.5
​
=674.3*horsepower
Lunati Voodoo 60123 Camshaft:

Displacement: 475ci

RPM: Estimated peak power around 6,800 RPM (this cam is more aggressive).

VE: 85% (estimated).

Horsepower
=
475
×
6
,
800
×
0.85
×
0.65
1
,
000
Horsepower=
1,000
475×6,800×0.85×0.65
​

Horsepower
=
1
,
733
,
925
1
,
000
=
733.4
*horsepower
Horsepower=
1,000
1,733,925
​
=733.4*horsepower
Summary of Estimated Horsepower:
Comp Cams XR290HR: ~674 hp

Lunati Voodoo 60123: ~733 hp

Key Notes:
These estimates are based on the assumption of 85% VE, which is a reasonable estimate for a street/strip engine with a strong, free-flowing intake and exhaust. If your heads flow better or if you have more aggressive tuning or higher VE, these numbers could be higher.

The cam with the more aggressive profile (Lunati Voodoo 60123) produces a higher peak power estimate, which makes sense as it is designed for higher RPMs and more aggressive power delivery.

Torque: A higher VE or more aggressive cam would typically give you more torque in the lower to mid RPM range, but your cam choices should still allow for solid low-end torque even as you reach the higher RPMs.

Final Consideration:
This is a ballpark estimate. To get a more accurate prediction, especially when it comes to the exact tune, fuel mixture, and other factors, you'd ideally want to run the engine on a dyno or use more precise software (like DynoSim or similar programs). However, based on the specs provided, you can expect approximately 674-733 horsepower depending on the camshaft choice

[kyle_blake]

That's cool , thanks for sharing!!

[steve25]

Even 290 Intake cfm @ 28" is not going to make you 674 hp no less 733!

[P@blo]

Maybe there is an AI dyno to make this all legit? lol

[Stan Weiss]

Like AI mine is still a work in progress. lol

Stan

[Danspeed1]

Its interesting but that's also why I am looking for real world advice. Supposedly this technology is 88.7% accurate; with that said a few of those camshafts are specifically for small block chevy. I'm not sure where or how it pulls its information

[P@blo]

You probably realize that all AI does is scrape the internet for information. What could go wrong? The worst recipies repeated on 1000 sites must be the best...

That's it, so there is no I in AI. The 13% it misses is the critical part. Like building a bridge ~86% correct (and that percentage is probably closer to 45% in reality).

[Jay S]

Nailed it!

Now there is no need to send the Teminator after me……

[Jay S]

Originally Posted by Stan Weiss

Like AI mine is still a work in progress. lol

Stan

That is looking good Stan.

[mgarblik]

I think that was a fun little exercise. Would have liked to see the results with a specified maximum RPM range of 6000. Much more realistic without spending thousands more for valvetrain stability. (Jesel or T@D shaft systems and so forth). Also, with no intake manifold specified, that really changes cam choices. I want AI on my race team!! The HP estimates are about 150-170 high IMO.

[Danspeed1]

Originally Posted by mgarblik

I think that was a fun little exercise. Would have liked to see the results with a specified maximum RPM range of 6000. Much more realistic without spending thousands more for valvetrain stability. (Jesel or T@D shaft systems and so forth). Also, with no intake manifold specified, that really changes cam choices. I want AI on my race team!! The HP estimates are about 150-170 high IMO.

Anyone can do this online using Chat GPT, this is very easy. I didn't get too specific because I was looking for ideas but I'm going to keep inputting combinations as I get closer to collecting all my parts and see how close it comes in. I agree, the HP numbers are ridiculous.

[i82much]

I work with generative machine learning all the time. These models are trained on what is called a next token prediction task, were they essentially learned to predict the next word that a human user would have said following the previous words that it is already said. While there is a lot more to it than that, you would probably expect that if 90% of human users recommended those camshafts on the Internet in similar applications, then a generative AI model would be about 90% likely to make those same recommendations.

these models also have what is called a temperature setting. When the mama uses a higher temperature, it is able to veer further away from the highest probability tokens. And more likely to say things that is not seen in the training data. That can give the illusion of creativity while at the same time making the model more likely to state things that are simply not true.

[Formulas]

One of the most critical parts of the model was left out of the input and assumed by the parrot, ... Actual head flow, or intake flow no carb data either, ... the assumption is a choke point in the model but AI has no brains to point that out.

I engaged with AI on Helicopters i once worked on and flew in ... It was giving a rundown on the AH-1G Gunship and said it had the same rotor system as the UH-60 Huey, Red lights and sirens went off in my head i challenged AI the answer was oh i miss spoke blah blah blah

I'm not worried about AI taking over I'm worried about people letting it.

[bdk1976]

I trust 'AI' results like this about as much as I trust a politician. Try asking it some moderately complicated questions in an area you have expertise in and see what kind of nonsense it spits out. Not surprising considering what kind of 'data' it trains on. In a lot of cases you're probably better off cutting out the AI middleman and asking some random idiot on facebook for their opinion.

We'll get there one day, but I think that day is further out than a lot of AI fanboys are predicting.

[grivera]

AI sources directly from the secret files of Bruce Fulper/Rock and Roll Engineering for all Pontiac related searches

[i82much]

you can have a great conversation with a generative machine learning model to get a general idea of what factors to consider in selecting a camshaft. You could probably learn as much and 20 minutes of talking in it with a generative model as you could in months of searching on this forum if you were completely new to the hobby..

once you get a baseline level of expertise and want to know things like specific camshaft specifications, your way outside the capabilities of a machine learning model given the current state of the art.

[Keith Seymore]

Originally Posted by P@blo

You probably realize that all AI does is scrape the internet for information. What could go wrong? The worst recipies repeated on 1000 sites must be the best...

That's it, so there is no I in AI. The 13% it misses is the critical part. Like building a bridge ~86% correct (and that percentage is probably closer to 45% in reality).

I had a college professor that would say:

"You build bridge. Bridge fall down and you want partial credit?!?"

K

[mgarblik]

Originally Posted by grivera

AI sources directly from the secret files of Bruce Fulper/Rock and Roll Engineering for all Pontiac related searches

Now that's some funny stuff right there! You could prove that out by asking AI what it thinks of Pontiac aftermarket blocks! That would let the smoke out.

[Nobuddy]

Originally Posted by P@blo

Maybe there is an AI dyno to make this all legit? lol

Skip the dyno, just take it straight to the AI racetrack.

[72projectbird]

Originally Posted by P@blo

You probably realize that all AI does is scrape the internet for information. What could go wrong? The worst recipies repeated on 1000 sites must be the best...

That's it, so there is no I in AI. The 13% it misses is the critical part. Like building a bridge ~86% correct (and that percentage is probably closer to 45% in reality).

In surprised it didn't suggest an 068 cam and to make sure he's using a Q-Jet. It must not have referenced too many Pontiac sites lol