This isn't anything profound, but I thought I'd share the results on my truck, along with some practical Eaton blower tech I feel I have happened upon first-hand...at least as it relates to my specific truck.

With just a 2lb pulley and REM intake, the truck made 376rwhp/440rwtq. The TQ is a little low b/c the dyno operator started the pull at 3500, which is after the TQ peak.

With the 4lb pulley, REM intake, and and LFP heat exchanger (which I believe made NO difference on a day like today), the thing made 393rwhp/482rwtq. This is SAE corrected. Actual #s were 417rwhp/511rwtq. Why couldn't we have raced today?!

I think the power is good for the minor mods. Nothing outstanding, but certainly no worse than average.

I did discover that the Eaton is running out of breath with my combo. With the 2lb pulley (and for stock trucks) peak HP is usually ~5100-5200rpm. Now with the 4lb pulley, peak HP is at 4700-4800rpm. Boost is not falling off (13psi), and the belt is not slipping. If the thing would flow more air, and make peak HP at 5200 still... I'd be at 405+rwhp easily.

I do believe from here the best mod is a KB or Whipple blower. I'm willing to bet peak HP will be back up at 5200rpm, and with the more efficient blower... 50-60rwhp gain running the same 13psi. By the time I spend the $$ on an upper intake plenum, long tubes, high-flow H-pipe w/ cats (to remain legal in my county), etc., I'd still have to turn around and run a 6-8lb lower/swap the upper on the Eaton to flow enough air to make that 60rwhp gain...and the cost would be approaching the KB.

I'm feeling like the limit to block/trans reliability is ~450rwhp and I want to get there the most efficient way possible, and a more efficient blower makes a lot of sense.
__________________
'04 DSG Lightning---393rwhp/482rwtq...minor mods
'00 Expedition XLT "Thunder"
'02 Corvette Z06 (11.xx @ 129mph)---535rwhp/515rwtq...Lingenfelter twin turbo...soon to be 590+rwhp.
'90 Mustang (10.xx @135)---615rwhp/594rwtq, Super Ford Mag. feature car..SOLD 9/3/02
www.wa2fst.com

 

Thanks for the info and post.

Try porting the blower and you'll be amazed at the gains from a 4#er. (on the top end)

Rich

 

Very good info.

So, even the 4lb lower maxes out below the peak HP RPM of the motor?

BTW, what RPM is the factory 380 HP rated at?

 

Well, the funny thing is that the Ford literature states 380hp @ 4750rpm.

But on my '99 (stock and with a 2lb) and on my '04 with a 2lb, and on just about every other truck I've seen that's mildly modified and has the stock Eaton... it ends up occuring at 5100+rpm.

I've been discussing this with an engineer friend of mine, and we feel like its an air _density_ issue more than an air _flow_ issue. I mean, we all know there are some guys making 16-17psi with their stock Eatons... some even have exhaust mods, so they are spinning their blowers a lot harder than I am.

If boost remains constant, then a loss of power w/ respect to an rpm gain would typically mean air density has suffered. IOW, the air intake charge is just getting too hot, compared to say, a KB blower making the same boost, but is able to carry out the power to a higher rpm.

Now, on a stationary dyno (and this one is above ground, so there was no fan simulating airflow across anything), we know you will never see the maximum efficiency of the I/C and heat exchanger (stock or aftermarket) b/c of a lack of airflow across it. My LFP heat exchanger does have a puller fan on it, and it was on, but its only pulling 400-500cfm, so that's certainly not as much airflow as if I were doing 70+mph down the road.

I understand that a ported Eaton will help, but have seen plenty of dyno graphs that show it, too, will make peak HP at 4700-4800rpm and begin to fall off compared to a KB which (even if it makes the _same_ power to 47-4800) continues to build power past 5000 without additional boost necessary. I believe this shows the value of it being more efficient and inlet air density is greater due to lower inlet temps.

 

Great post!

Just don't forget what the goal is. We always want to buzz the motor (reving past the peak HP point) so that when the next gear comes and the rpms drop.. were still in the meat of the torque curve.

My rule of thumb w/a 3 speed auto has always been 500-700 rpms in 1st. And 200-300 in second. This usually seems to work for me. But then when it comes to manual tranny cars you just have to look at the gear ratios. Especially on the little 4cyl econoboxes.

Rich

 

Rich,

I'm in 100% agreement with you. In theory, you _always_ want to shift past peak HP. That's why guys with centrifugal blowers that make peak power AT their redline always go slower than what their dyno #s say they should. I've preached this for years, but it usually falls on deaf ears.

I was just more interested in the fact that while I did see a nice increase in peak HP/TQ, the peak HP occurred 400rpm lower than it did before I swapped to the 4lb pulley.

 

Just for reference I have my dyno plot n front of me.

Mods are :

6lb lower / no port work
Stock upper
Long tubes w/ cats
Rem intake

Conservative street tune :

Peak HP : 403.2 @ 4700rpm
Peak Trq : 509.2 @ 3100rpm

Boost 14.5 psi.

Bob

 

Nice write up

FWIW
I made similar gains when I went from the 2lb to the 4 lb. And almost the same amount of gains when I went from 4lb to 6lb. But really picked up when I went from an unported Eaton w/ a 6lb to an Apten ported Eaton w/6lb.

Wait till you see the gain going from an Apten w/ 6lb to a Magnum w/8lber

 

Great numbers Wess Let me know what blower you decide to go with since I'm in the same boat as you. My goal is exaxtly what yours is

 

Because the literature states flywheel horsepower. Chasis dynos are giving your rear wheel horsepower. I'm sure the drag through the drive train is good for a couple hundred rpms.

 

I agree
Great post WA 2 FST, And nice Power for the Mods

Since I WAS pushing my stock Block way past what I consider safe, I left my tunes like this



4+2+75HP of Nitrous

As you see my Torque stays 600 ft lbs to 4300,
but then drops off BIG TIME.
My 500 HP stuck around a little longer to 4700,
and then drops off, but not too bad

BUT WHEN YOU THINK ABOUT IT
With an A/F at or below 10
500/600 @ 4500 RPM, and 450/450 @ 5500 isn't all that bad.
50 HP drop off is actually great, but that 150 ft lbs of Torque I lose would def come in handy.

I currently run 25 More Nitrous HP than that Dyno Run,
(unfortunately DO NOT have any Dyno Runs of it),
BUT Sat the truck goes to Sal for the Rods, Threads in the Heads, and fresh Rings, Gaskets, Pistons, etc....

Next Season I will be running 6+2 + 150-250 Nitrous HP
Plenty of Dyno Tuning and Graphs will follow early 05

Here Gator Gator....................

 

WA 2 FST: A side note of interest: Another factor that you have to look at in comparing the 1999 to the 2004 is the difference in the intake manifold itself. The 1999/2000 is basically an open plenum, whereas the 2001 and later has more separated runners. I've been involved in a manifold swap/flog and was really amazed at the difference in the manifolds. The late manifold looks like they figured out to pick up several lb/ft of torque. The difference in the manifolds should move the torque peak down in rpm while increasing the torque numbers accordingly.

Another of my random thoughts: Why aren't we plumbing the PCV into the manifold below the intercooler, so the oil does not clog the cooler. The factory put it before the throttle body because it always sees vacuum. Putting it in the manifold would require a one way valve to avoid positive pressure in the block, but would keep the intercooler clean.......other thoughts?

 

You can say that again!