What happens if a you port a stock pullied Eaton?

I know that most people port their Eaton and put a 4-6# lower with a 2.9 or 3.1 pulley, but I've always wondered what would happen if someone got a Steigemeier or Posi ported Eaton and just threw a stock pulley on it?

Would the car make less torque? Would the powerband move up? I've always wondered what would change?

HPLouis said:

I know that most people port their Eaton and put a 4-6# lower with a 2.9 or 3.1 pulley, but I've always wondered what would happen if someone got a Steigemeier or Posi ported Eaton and just threw a stock pulley on it?

Would the car make less torque? Would the powerband move up? I've always wondered what would change?

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Good question im wondering myself since im actually running a stage 8 port from Steg on a stock setup lol

I would say it would just give a little bump and extend the torque curve out a little further which will net you a few ponies.

Not much I think. Local guy ran a ported blower with a stock pulley on a warmed over engine. Ported heads, cams, etc. Made a whopping 5-6psi with with stock pulley.

01yellercobra said:

Not much I think. Local guy ran a ported blower with a stock pulley on a warmed over engine. Ported heads, cams, etc. Made a whopping 5-6psi with with stock pulley.

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Wow, I guess the port caused less restriction so he lost boost. Well, at least he was more efficient.

HPLouis said:

Wow, I guess the port caused less restriction so he lost boost. Well, at least he was more efficient.

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Well ported heads and cams were probably the boost loss. Just not spinning it hard enough to keep pressure in the manifold with an engine breathing like that.

Porting couldn't hurt but might as well up the boost. Hell a 3.0 on a non-ported would be way more bang for buck vs stock pulley ported.

Pulled this off of Stiegemeiers site

just porting alone is suppose to give you 40hp

AFLOCOBRA said:

Pulled this off of Stiegemeiers siteView attachment 1712653

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Yeah, the claim is 40hp, but I’ve never seen a dyno sheet to verify actual HP increases with a stock upper and lower. Outside of wanting an otherwise stock looking setup, it seems to bring a minimal power increase for a substantial cost. JMO.


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True that, would be curious to see what numbers my car would put out..idk if i want to pay 250 for a dyno tho lol

CobraBob said:

Yeah, the claim is 40hp, but I’ve never seen a dyno sheet to verify actual HP increases with a stock upper and lower. Outside of wanting an otherwise stock looking setup, it seems to bring a minimal power increase for a substantial cost. JMO.


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CobraBob said:

Yeah, the claim is 40hp, but I’ve never seen a dyno sheet to verify actual HP increases with a stock upper and lower. Outside of wanting an otherwise stock looking setup, it seems to bring a minimal power increase for a substantial cost. JMO.


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Wow, good point. Thanks for posting.

AFLOCOBRA said:

just porting alone is suppose to give you 40hp

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Not to sound like a jerk but they have made A LOT of claims and products that didn't really stack up. Venom cooler and lightweight rotors come to mind. Hell 2k for a ported setup with bigger plenum and TB? There is a Gen 1 TVS in the market right now w/ GT500 TB for $3500 and is in a different galaxy. When they had the stage 4/5 for like $500 years back it was a deal. They priced themselves out of the market. Dunno who would pay that now.

Don't waste the money. 2.8 or 3.0 get you in the mid 400s at the wheels for like $100 plus the dyno. These cars have been around a long time now. The formula for easy HP has be proven.

I agree with you. My first setup with a 2.90 upper (and the typical supporting mods) netted 457/480. That setup was the most fun I had after living with the factory upper for the first 3 months of ownership. For what I paid for the porting & revised dyno tune, and an approximate increase of 35hp, I should have left the blower alone.


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was that 35hp to the wheel gained?

CobraBob said:

I agree with you. My first setup with a 2.90 upper (and the typical supporting mods) netted 457/480. That setup was the most fun I had after living with the factory upper for the first 3 months of ownership. For what I paid for the porting & revised dyno tune, and an approximate increase of 35hp, I should have left the blower alone.


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Yes, that’s WHP.


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