I've got the 5.0 auto in my '91 2wd Reg. cab and have a buddy who has the 4.9 auto in his '90 (same model). When he comes up to visit next summer we are going to run the trucks against each other to settle a friendly bet (nothing serious, just a 2 out of 3 run down a deserted road). In anticipation I've been doing some reading on the boards about the power ratings of the two engines. Here is what I have found:

'91 5.0: 185HP @ 3800rpm
'91 5.0: 270 ft/lbs @ 2400rpm

'90 4.9: 150HP @ 3400rpm
'90 4.9: 260ft/lbs @ 2000rpm

According to the numbers, the 5.0 should be the clear winner in both stump pulling and flat out running. According to popular experience, the 4.9 is actually the better hauling motor with some claims that it will beat the 5.0 in a straight up run.

I not trying to start a flame war, but the numbers don't support the 4.9 as a better engine. The 5.0 makes more HP and Torque at appx. the same rpm as the 4.9. Can anybody enlighten me on why the 4.9 is the preferred work motor and why the claims that it will beat a 5.0? I'm looking for solid information. A good jibe if I win and a good excuse if I lose.


DirtBee
'91 F150 XLT Lariat, Reg. Cab, 2wd, 5.0 Auto.

 

The main difference is the location of the torque curve.

The 4.9 makes better low end torque and it's peak torque also occurs at a lower RPM. Keep in mind that the peaks don't really tell the whole story. Average lockup speed of the converter on these trucks is only about 1800 RPM. At this RPM the 4.9 is making more torque. I don't have any torque curves or dyno runs to prove this, but a ride in both trucks will make it evident.

The 5.0 simply has a higher curve. It takes more revs to produce the peak torque and the "fat" part of the torque curve goes higher in the rev range. As an example, the 4.9 is making 231 lb ft of torque at 3400 revs. The 5.0 is making 255 lb ft at 3800 revs.

Since most people don't rev their trucks past 3000-3500 on a regular basis, the 4.9 will feel just as strong if not stronger in daily driving and towing situations.

At the track or in a race situation, the higher curve of the 5.0 will overcome, mostly due to shift points. When the 5.0 grabs a gear at WOT, the next gear places the RPMs very close to it's torque peak. When the 4.9 does the same, it is already on the downward slope of the torque curve.

All other things being equal, you should win a drag race. But don't be surprised if you lose some ground right off the line. Simply put the 4.9 advantage is sooner, the 5.0 advantage is later.

 

Excellent job!!!

That was really well explained! My 4.9 can beat most stock 5.0 trucks right now, but it wasn't always that way. I have made some very effective mods, and I've got a 5 speed. Those are the main reasons. If I had an automatic, I'd lose, even with the mods.

Lastly, don't believe the numbers that are posted by the factory, either. The only way you'll know what your vehicle produces is to dyno it yourself. I've never in my life seen a stock vehicle that matched the factory specs when dynoed. 16 years ago, while taking an engine rebuilding class at the local college, we received 2 identical Camaro Berlinetta's as donated vehicles from the local Chevy dealership. We dynoed them, and got very different results. I don't remember the actual numbers, but it worked out to almost a 10% difference between the two. Makes you kinda wonder.

Take care,
-Chris

 

Also, you better make sure your friend doesn't have a BOSS 300, or you're toast!



Take care,
-Chris

 

signmaster,

Thanks for the insight, that was good info. I wouldn't have thought that 400 rpm would make that much of a difference but it sounds like the proof is in the driving. In this case I'll take the driver's expierence over the factory specs and keep my mouth shut until the results are in.


DirtBee

 

I've got an '88 F-150 5 spd. 302(EFI), and an '86 F-150 4 spd 300(carb.). They are both very nice trucks that have been very well taken care off. The 4.9 is my favorite truck to play with and for hauling around the farm I think....but, I would never race it against my 5.0, it just wouldn't keep up. I know it's not fuel injected, but, I just don't feel it has what it takes to keep up with my 5.0.

 

Those Boss 300s are quick, but we all know the SHO 302 will eat it for lunch! To my knowledge there is only one Boss 300 around. There was a SHO 302 at my place but it's gone until I make some more decals.

It's a good thing the owner of these trucks live on opposite coasts. A match up between these two rare trucks would surely produce times that would humble all the Lightning owners. ...cough....cough....

 

The longer the race, the larger your advantage. Keep in mind torque is what pushes you back in the seat. HP is a measure of how fast this work is performed.

It is argued by many that torque is more effective at higher rev ranges because it produces more HP. On a light race vehicle this is probably true, but in the real world our trucks have to work up to that RPM range. This means working through the are that doesn't make as much torque.

Food for thought..... A modern Formula 1 car makes about 850 HP, but does so while only producing about 250 ft lbs of torque!

So if you want to talk some smack, just tell your buddy that your truck makes more torque than a BMW Formula 1 engine. Just don't mention that his truck also does.

 

I own, both a 89 300 5pd and a 93 302 auto, and I think w/out a doubt that the 302 would have the great advantage as far as a race. If you tried a pull off, i guarantee the 4.9 would whoop some butt, but if you're racing, i think you'll be alright. Have fun.

 

where did you get this info of hp and torque

 

I replied to your thread...

 

I've beatin a few 5.0L's on the street, haven't had a chance with one at the track. (but have had my *** handed to me a few times also)

My cousins 5.8L reg.cab long.bed is running a 18.7 compared to my 17.6 1/4 mile.

But if your buddys 4.9L is pretty much stock you ahve nothing to worry about.

 

Yeah ya better watch out for those Boss 300's , I don't know if I would put my little 302 against a 300 but I'm sure I'd lose. I'm sure they have special heads

 

on the 302 side of things i have a 96 reg cab long box with a e40d in it and for a stock truck(with home made 3inch single ex) this truck goes like hell it cleans up any other 302 i have ran all other trucks have been in the 93 and older.i can walk all over 01 318 5-speeds sb 4x4 reg cabs and a 96 360 4x4 excab sb, now i know that my truck has a H.O firing order and is a mas air truck but what is the specs on a stock cam????

 

Now, what I have had explained to me is that one of the big advantages of the 300 over the 302 is that the 300 is mounted lower, and that the weight is centered farther back and lower in the chassis, but that the way a I-6 is set up is somehow more effective than a V-8 in making torque. Is this true, or should I stop listening to my friends?