LoPo vs Explorer vs HO Torque Curves

[89GrandMarquis]

After quite a bit of searching, and then working with Engine Analyzer software, I've put together some torque curves for us all. The LoPo curve is based on a dyno run, while the rest are from the software using Explorer and HO cams, with E7 heads (thermactor bosses removed).



I did this work to validate my own cam choice (I bought an Explorer cam) before I did the work to install it. Depending on the various inputs, the results are consistent: slightly more torque down low, and less up top (with the Explorer). Since I'll be sticking with the 4400 RPM governor, I'll accept the trade off. For you - you make your own decisions.

P.S. Since all I care about is torque numbers, the HP is not included.

[87mefull]

Is that a with a bone stock MPFI lopo? Sad how the torque curve is all down hill vs an HO or Explorer motor.

[89GrandMarquis]

Stock motor, no air box (3" intake tube with conical air filter) open exhaust after the y-pipe.

[BlackHawkA4]

Who opens the exahust after a Y pipe. :-P.

Nice compare sheet.

[Lincolnmania]

wow my ho in the towncar has a much wider tourque band than that.......must be those thumper heads
scott

[Roach III]

My lopo seems to gain power with rpm increase.

[Blaze86Vic]

Yeah, put a complete exhaust system on the car and you will get a much more realistic curve. PS: Why is the LOPO curve drawn in by hand?

[89GrandMarquis]

LoPo vs Explorer vs HO Torque Curves

Yeah, put a complete exhaust system on the car and you will get a much more realistic curve. PS: Why is the LOPO curve drawn in by hand?

A complete exhaust should change the results slightly (5 to 10 ft-lbs).

The curve is drawn in by hand because the first two curves came straight from the software. The LoPo curve was copied from a dyno sheet.

And this is NOT my car on the dyno - its from someone over in crownvic.net. But for that matter - who dyno's a near bone-stock LoPo? Seems to be a waste of $$$. I've got duals out to the bumper!

My lopo seems to gain power with rpm increase.

I agree that the "twin-cheek" g-meter can be misleading (mine is not calibrated). My GTech Competition Pro (an in-car HP/TQ datalogger) pretty much agrees with these numbers.

Remember the following ratings:
LoPo1 => 270 ft-lb at 2200 RPM
LoPo2 => 270 ft-lb at 2000 RPM (different source)
HO => 300 ft-lb at 3300 RPM
Exploder => 288 ft-lb at 3300 RPM (with GT40 heads, NOT E7s)
Exploder => 280 ft-lb at 3500 RPM (same as above, different year)

Anyway, I've seen other number that vary a little here or a little there - but my goal was not minute accuracy, but overall profiles. Generally, one would expect that Explorer to more provide more torque, but fall off earlier. The curve agrees. The Explorer curve is with E7s. The curve changes with GT40s - fattens up pretty much everywhere. Also note that FORD provides most of these ratings. They are torque peaks. On each side of the peak, the curve drops - plain and simple.

My own GTech results show a continually decreasing TQ curve for my non-HO motor. The dyno results show this, too. Whether the LoPo peaks at 2000 or 2200 RPM isn't an issue - the issue is mainly - where is the peak and how broad is the curve.

Again, other changes from stock exhaust will change the curves again. How? Generally you will fatten up the upper RPM numbers but potentially weaken the low numbers.

I would offer this advice to those considering the Exploder cam. If you are 100% confident that your engine mods will stop after you put in the Exploder cam, AND you want more low-end grunt, AND you will stick with your stock governor, the Expoder cam MAY be for you. With an Exploder cam, you just to realize that no matter what you do after the cam swap, the upper RPMs just will fall flat (compared to the HO).

Why did I buy the Exploder cam? Main reason: $$$. For $40 shipped to my door I got a no-miles Exploder cam. I didn't want used, I wanted new. If I couldn't buy a new cam in that price range, then I'd be sticking with the LoPo cam and E7 heads. In addition, I wanted as much down-low grunt as I could get. If my decision bothers you, then please send me $$$ so I can buy a no-miles HO cam.

[N A]

Who opens the exhaust after a Y pipe. :-P.

Nice compare sheet.

Me!!! When I bought the Grand Marquis last year, the previous owner used "wire" to hold the single exhaust on. The exhaust system after the Y-pipe was corroded beyond belief from all the road salt we use up here in the Northeast. I sawed off the exhaust after the Y-pipe and haven't bolted anything else on yet. (The car sounds wicked evil)!

who dyno's a near bone-stock LoPo?

I did!!! Everyone always says their car is making this much horsepower or that much horsepower. It's all bullshit until you strap it to a dyno or run it at the track. I dynoed my GM to get my baseline numbers. The shop saves the data and compares any changes I make when I go back. I'm doing the HO conversion soon and I wanted to know exactly what the car is making "before" and "after" I bolt on the parts. I also wanted to know exactly what my car puts to the pavement, not anyone else's numbers. You wanted to use the Explorer cam and that's fine with me. Other guys here use the HO cam and that's fine with me too. I'm deviating from the stock HO recipe. So stay tuned!!!

[gadget73]

The stock HO is really a fairly gutless engine under about 2200 rpm. Anyone who has ever driven a car powered by one will tell you that mashing the pedal makes the motor pick up speed, but as soon as it hits 22-2500 rpm, its like you switched on two more cylenders and the thing goes like a scalded dog. Its just the cam and head flow characteristics that make them do this. Better heads widen out that torque curve a lot. I've driven Scott's car, and it doesn't have that 2500 rpm "kick in the ass" that my car has. Only real difference in driveline is the rear and exhaust.

[Southern_Pride]

Thats why every time I pulled up to a stop light against an HO foxbody they wouldnt touch the Lo-po in the capri out of the hole. I like my lo-po. All the ass out of the hole where you need it around town.

[gadget73]

Only problem is the heads on them suck too. Trucks are an E7 headded lopo motor. Torque down low, plus more airflow and 19 lb injectors. Thats really the engine that belongs in our cars. If you just put better heads on a standard lopo you get pretty much the same effect but ideally the ecm would need to be reprogramed to allow for fatter injectors and airflow. Hmm, you know that would be a really spectacular use for a 91 cali mass air ECM.