Ported Eaton 2.93/8# combo, switch?

Av3ng3d

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I purchased a posi ported Eaton Cobra that has not been driven/tuned since getting the posi port put on it. Anyways, I measured the lower pulley and it turned out to be a 8lb metco lower! Upper pulley is a 2.93. I've already established through research that this combo will overspin the eaton quite a bit, but now I am debating on what will be my best option in order to correct it before sending the car off for a tune.
The alt pulley is a 3.7".. so keep this in mind. Whichever route I go I want to not have to change the alternator pulley if at all possible.

Should I replace the upper pulley with something like a 3.1 or even stock size?

Or Should I just replace the crank pulley ring with a 6lb and retain the 2.93 upper and 3.7" alternator pulley? I saw one for sale on here for dirt cheap but not sure if the 6lb lower will work well with upper pulley and alternator pulley.

My goal is to make it to the 500whp mark (Car has a KB BAP, 60# injectors, sct ba2600, bbk 65mm)
 
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KLLR SNK

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Put a 4lb lower on it with your 2.93 upper and easily reach your 500hp goal with a good dyno tune.
 

Av3ng3d

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Put a 4lb lower on it with your 2.93 upper and easily reach your 500hp goal with a good dyno tune.
How do you think the 3.7" alternator pulley would do with the 4lb lower, wouldn't it undercharge?
This was my only reasoning behind taking a 6lb lower into consideration instead in order to retain the alternator pulley that is on it now.
 

KLLR SNK

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Put a 3.2" upper on it then. But I would change the alt pulley instead. I am sure there are plenty of dead alternators out there with a stock pulley that someone would treat you right price wize if not free. You will have to buy a belt regardless.
 

Av3ng3d

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Well I ended up just buying the 6# lower that was for sale in the classifieds because it was the cheapest/quickest route. I could not find a 4# lower ring, and I did not want to buy the entire crank pulley kit when I only needed the ring. Same thing with the upper pulley. If I could have found a used 3.1/3.2 upper I would have gone for it but could not find anything. Hopefully the 6# works well with the 2.93 and ported Eaton. I've read mixed things about the combo. Some say it's a great combo for torque, some say otherwise. The combo "should" make around 17.1psi.
 

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stangfreak

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I would have went with a 4.b lower. That little eaton will just run out of steam. Top end will suffer, the heat soak will be insane. Once the tq over rides the hp, you know its being over spun. But the eaton does work being over spun to a certain extent.

I was making jokes about one day seeing 8lb lowers on eatons. guess people really do it lol. Next thing I will is, 2.76 upper 15lb lower. Its ported so its ok!! lol
 

Av3ng3d

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The first owner put on a 8lb lower while retaining the stock upper. It was tuned for that setup...and still is up until this point.
Owner #2 was told the car had a 4lb lower.
This winter owner #2 put a ported posi on the car that already had a 2.93 upper, then sold the car to me before he had the chance to really do anything with it due to the time of season. It has not really been driven to any extent with that current setup.
Owner #2 told me it had a 4lb lower because that was what he was told by owner #1. I then purchased all the supporting mods to get full potential of the posi such as injectors, BAP, FPDM rewire, and SCT BA2600 MAF. I Decided to measure all pulleys because I wanted a fresh belt on the car before sending it to be tuned and then that is when I discovered it was actually an 8lb lower. So that left me with a bad pulley combo that I was not expecting after the fact that I've spent a ton of money on the car in the last month (including the price of the car) and still need to send it off to be tuned once I get the 6# lower on it. I am just trying to get the car in good enough shape for the spring to enjoy it at this point.
I could only find the 4# metco sold as an entire kit and could not justify shelling out another $429 for a crank pulley kit when I needed only the ring. Not to mention the pulley charts show only a 0.9psi difference between a 2.93/4# and 2.93/6# pulley combo (16.2psi vs 17.1psi) so I had to bite the bullet and go with the 6# for $45.
 

Quick Strike

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I ran ported Eaton, 2.8 upper and #4 lower for three or four years. That is almost the same blower speed as your combination. I have a box of low 11 second timeslips and a better driver would have has this car in the 10s. It had plenty of power up top. I think the aftermarket HE also made a difference here.
 

apex svt

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I run a 3.1 8# combo, car makes great torque 530 on pump gas. However saying it gets Hot is an understatement, I could cook an egg on my blower after ripping on it for awhile.
 

Posi

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If you don't street race with no cool down you're not overdoing anything you're at max boost pretty much proven on the track and dyno. A 6lb over a 4lb will get you a few more hp and some decent torque. Let alone it'll be instant when you stab the throttle. I ran that combo on the street and drove my car hard. Just pay attention to when things are cool and they aren't. If you're in traffic forever in 90+ degree heat when it clears don't stomp on it. Cruise for a little to let things cool off then go full throttle. You can still get on it hot but just shift a lot earlier...
 

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IMO you do need a ported tb combo minimum I would recommend a ported Dragon setup for max power.
 

Av3ng3d

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If you don't street race with no cool down you're not overdoing anything you're at max boost pretty much proven on the track and dyno. A 6lb over a 4lb will get you a few more hp and some decent torque. Let alone it'll be instant when you stab the throttle. I ran that combo on the street and drove my car hard. Just pay attention to when things are cool and they aren't. If you're in traffic forever in 90+ degree heat when it clears don't stomp on it. Cruise for a little to let things cool off then go full throttle. You can still get on it hot but just shift a lot earlier...
Excellent (and informative) response.
Thanks!
 
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Av3ng3d

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IMO you do need a ported tb combo minimum I would recommend a ported Dragon setup for max power.
For what it's worth the car came with a 65mm bbk throttle body, although I'm sure a ported dragon is a much better choice.
 
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Posi

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Meh, that'll work just has to be ported and matched. You can port the daylights out of those too. If not you're costing yourself at least 15hp with that pulley combo and some rpm's for peak as it'll peak sooner.
 

apex svt

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Meh, that'll work just has to be ported and matched. You can port the daylights out of those too. If not you're costing yourself at least 15hp with that pulley combo and some rpm's for peak as it'll peak sooner.
Does the same go for a acuffab sbtb and plenum? Considered getting mine ported to match but didn’t know if it was worth it.
 

Av3ng3d

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So I may have run into a little bit of good luck with this car finally.
It looks like the throttle body and plenum have already been ported? I'm not 100% sure on the throttle body because I don't know what the bbk looks like out of the box.
The only thing I found negative was the gasket between the throttle body and plenum was not cut to match the port job but that's easy enough to fix when I reinstall.

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Posi

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Does the same go for a acuffab sbtb and plenum? Considered getting mine ported to match but didn’t know if it was worth it.


10hp for upper only pretty much and it'll peak a little higher after. Just have to work the plenum.
 

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