4 lb lower question

[Nervouswreck]

What are the “dangers” of doing a lower pulley? I’ve heard you can break your crank , it’s not “caged” , etc etc.

I have a 2.76 upper, Posi Ported blower / plenum/ and TB , and all Metco dual bearing idlers . Plus a Mechman billet 230 Alternator.

Am i ok to go with a 4 lb lower?
How much power will it actually add?

Thank you !!!!!


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[Quick Strike]

The worry about a lower hurting the crank with an unsupported lower starts with blowers larger then 2.9L. The extra load of of spinning a larger blower instantaneously can be hard on a crank that is no prepared appropriately. Generally these cranks are drilled deeper and studded to handle the additional load. You will be fine with your blower and a lower.

A 4# lower and 2.8” upper with a ported everything Eaton should give you in the neighborhood of 535/535 RW HP/TQ on 93 octane using a healthy stock motor. You might want to do a larger alternator pulley to slow it down some, but I had that combo without any alternator pulley for 25k miles with no issues.


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[Quick Strike]

A good aftermarket heat exchanger will also be needed.

You will probably need larger injectors, a larger MAF and al least a BAP to safely maintain that power level. Some cars won’t, but it is a safe bet you will.

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[Nervouswreck]

A good aftermarket heat exchanger will also be needed.

You will probably need larger injectors, a larger MAF and al least a BAP to safely maintain that power level. Some cars won’t, but it is a safe bet you will.

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I have an Afco DP heat exchanger,60 lb injectors, VMP BAP , BA3000 MAF, and freshly rebuilt motor


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[BLOWN9646]

Throw in a pair of GT pumps, mod FPDM (or dual setup) as well, and run E85. 60's might be close but worked for my ported 2.93/4lb

 

[KevinsVertTerminator]

Based on everything that i have read if you street the car it will heat soak quick with the 2.8/4lb but is better at the track. For street, based on much reading but no real world experience, i concluded 2.93/4lb with a port is the optimal performance on the street for a 1.6 Eaton

 

[Quick Strike]

I would go back to your proposed combo for a daily driver. It had great performance with minimal maintenance. My drive to work was 40 miles to and from daily. There was no evidence of heat soak (a few Vetts, Camaros and bikes would say not either). It would run 11.20s granny shifting all day at the track. A better shifter would have had it in the 10s. BTW - our stock Eaton is 1.8L.

 

[stangfreak]

Not sure why you guys still want to over spin the eaton to the moon. Your shoving 19-20lbs of boost in a little eaton m112. My 2.9 whipple, at 26lbs on a stock motor made no more power than it did at 23lbs. even whipple said its just maxed out. and thats a 2.9 Liter blower. Ported or not, you guys running a 2.0 upper with a 35lb lower are just making the blower inefficient. when you street the car, do you think your rolling around with the same power as you did on that one dyno pull with the fans blowing? even your larger heat exchanger won't do anything. If you have your heart set on a lower pulley, just do a 2.76 upper 2lb lower.

you will make more tq when adding boost to the eaton bc it can only make so much hp. its a small blower. tq will increase, but, will heat soak so fast. venomous john who went 10.80s with a ported eaton had a 2.8 upper 2lb lower. once he lowered the boost on the eaton the car became more efficient and faster. That was the 10 second pass and it was on stock suspension full weight cobra. even had the spare tire. just my opinion. The cars been out for a long time. No one is reinventing the wheel.

 

[Quick Strike]

I have numbers on multiple pulley combinations since the car went through a progression of pulleys with a ported Eaton. My car made 485/485 RW HP/TQ with a 2.8" upper and ported Eaton. It went consistent 11.7s with my granny shifting, and made a little over 14# boost. This would spin the blower around 17,600 RPM at a 6500 RPM engine speed. The same car made 535/535 RW HP/TQ with a 2.8" upper, 4# lower, ported Eaton, welded and ported plenum and ported TB. It went consistent 11.2s this way with my less then optimum shifting style, and it was still only at 17# of boost. This would spin the blower at 19,900 RPM at 6500 RPM engine speed.

I cant say I shifted .5 seconds faster in the quarter, but I did add 50 HP/TQ. I also don't think 17# of boost is spinning the Eaton to the moon considering the OPs Eaton, plenum and TB are ported. No one here is suggesting spinning a stock Eaton with that much pulley.

 

[KevinsVertTerminator]

I would go back to your proposed combo for a daily driver. It had great performance with minimal maintenance. My drive to work was 40 miles to and from daily. There was no evidence of heat soak (a few Vetts, Camaros and bikes would say not either). It would run 11.20s granny shifting all day at the track. A better shifter would have had it in the 10s. BTW - our stock Eaton is 1.8L.

1.83, i agree typo. I read so much about heat soak on the street and i live in a state that breaks 120 some summers so went conservative with the rpms and got the 170 thermo and alco HE w/ fans. Well see come summer!!

 

[01yellercobra]

A friend ran a 2.76 upper and 4lb lower on a steggy stage 4 with no issues. He put about 100k on that combo too. I was surprised the IAT's were lower than I expected when I tuned it. Granted I still tuned it on the conservative side as I know how he drives. It was a fun set up for sure.