with these two pullies being available, how close is the eaton to being maxed out completely?

 

These pulleys will push the Eaton well beyond it's efficancy curve...

 

I don't really believe in any of those efficiency curves.

I am putting a 10# lower with my Eaton and I think those numbers will be different, since I will have a ported plenum, P & P '01 intake, P & P heads, JL Supercooler, plus the longtube headers that I have.

Also how can you max out the blower if you have nitrous spraying in it at a whopping -70 degrees.

 

Well your situation is a tad bit different then what L boy is saying.

On a stock truck is what he's comparing the blower pulley size too. If you have counter measure's to cool down the blower and make it more efficient its going to be a much different graph.

 

I don't think you are changing the blower's efficiency, but attempting to compensate for it.

 

exactly!


But running an intercooler is compensating for it also. thats why the KB runs so well on our trucks.

 

If the truck keeps getting faster then the blower is still producing hp, but I think thats a fine line to walk on a stock bottom end

 

A good friend of mine has a 1986 Buick T Type Turbo, pushes 21 LB of boost. 80,000 mi stock block. Are you people saying a 1986 V6 Buick has a stronger bottom end then our Lightnings? Ed

 

86 T-type? I had one of those, ran a 11.80 @ 114 with a completely stock motor and 148,000 miles on the clock, but..... you are comparing turbocharging to the use of a belt driven supercharger.

To answer your question, Yes, the Buick is a stronger motor especially in the connecting rod and piston area, the L's main weak point. To give you an idea how strong the bottom end design of the Buick is I have a friend with a 86 GN that turns 10.60's @ 127 mph with a bone stock bottom end on 26" X 10" ET Streets weighing in at 3,800 lbs (Still has the stock steel chrome wheels on it ). The Buick V6 was also designed to turn around 4,800 rpm where most L's I know spin around 5,400 to 5,500 rpm after being chipped. The supercharger also acts as a power drain on these motors using somewhere in the neighborhood of 50-75 hp to turn the blower itself where the turbocharger runs on excess exhaust energy and beyond choking the exhaust a bit doesn't really cost much power to use.

 

Probably. The rods are the weak link on the stock L bottom end.

 

I have JLs 8 pound lower pulley on my 01. the only thing thats not efficent is the rubber comming off the tires. Screw them graphs bolt that big azz steering wheel looking pulley up and have some fun ~!

 

i agree with you, i have #2 upper and a #8 lower on my 99. are you going to try the #10 or stay where you are at?

 

From an efficiency standpoint, the Eaton is maxxed out stock. From my Web site :

"As stated by one tuner: "Expected gains from the 4 pound pulley is 40 lbs.-ft. torque and 15 HP. Expected gains from the 6 pound pulley is 50 lbs.-ft. torque and 18 HP." Another tuner concurs: "18 lbs.-ft. and HP by 8 on the 2 Lb. pulley, 40 lbs.-ft. and HP by 15 on the 4 LB. pulley, and 50 lbs.-ft. and HP by 18 on the 6 LB pulley."

As a rough rule of thumb (extremely rough), a perfectly efficient 15 PSIG should double the HP of an engine (normal air pressure is about 15 PSI, so 30 total PSI=15 PSIG). Do the math and a perfectly efficient PSI should be worth about 6.6% gain.

Assume a 220 rwHP normally aspirated 5.4. Add a perfectly efficient 8 PSIG (theoretical 53% gain using the above rule of thumb). The expected rwHP should be about 335, which is about what one should expect from a stock Lightning. Add 4 more perfectly efficient PSIG (another theoretical 26%). That should yield 422 rwHP, which would be an 87 rwHP gain. But it doesn't-- it only produces 15 rwHP. A perfectly efficient 6 PSIG pulley should yield 467 rwHP! But it doesn't--it only produces 18 rwHP, or a measly 3 rwHP gain for those extra two PSIG.

Not only are the gains small with a 4 lb. pulley (only 3.75 rwHP per PSIG), they are even smaller with the 6 lb. pulley (only 3 rwHP per PSIG)! This is compelling evidence that the Eaton is out of steam when overspun on a 5.4.

Note, however, that we are talking only in terms of peak power--not area under the curve, which is what wins races. The midrange increases (when the Eaton is not being overspun) can be large. Jacking up the boost is not a sin if the supercharger is not being overspun. It is surprising that no one has tried jacking up the boost with bigger crank pulleys, but LOWERING the engine redline to keep the M112 in a reasonably safe and efficient range. It's all about area under the curve! Lowering the redline to 4,500 would reduce max supercharger RPMs by 16.7%. Using the max pullies used by Holdener, that would result in a maximum supercharger RPMs of 14,700, only 1,700 RPMs higher than stock. Food for thought."

If you want to flame or call me an egghead who don't know jack about real racin', please read the whole piece first. Just my $0.02.

TLS

 

Very well written post, Tim!

But at the same time, compression stress and is just as bad as RPM stress.

 

I'll give an example. we have a 99 lightning that we do alot of testing with along with the 01. we took the 8# lower pulley and made 4 passes on the 99 ( it also has a 11/2# upper). all runs were made in 80* 12.0,12.0,12.1,12.1 @ 112. we then put the 10# on with NO other changes i watched the A/F's and timing. We them made 4 more passes. Not 1 run was a 12 sec. pass ALL were 11's. 11.8,11.8,11.9,11.8 @ 114 Our 60 fts.Our 60fts. were amazing all were 1.63's &2's. No doubt this Eaton is well over taxed! but it still continued to make the truck faster in the 1/4. I know the blower is being over spun. It would make 19# of boost until it hit 5,200 then the boost would fall off to 16# up to my shift point of 5,600. we tried lowering the shift points but it didn't help any. So i think 19# 0f boost on the stock Eaton and running consitent 11's. was a *major* accomplishment. And yes the engine is a JLP. with all the goodies to keep it from blowing apart! JLP