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dparkguy
07-27-2009, 08:45 AM
I want to replace the stock cam with one that provides better torque. I have 5 speed with 33" tires, stock 3.73 gears. I don't want to upgrade gears yet. Will a different cam make me happy?

fastpakr
07-27-2009, 08:47 AM
No.

Tee Rev
07-27-2009, 11:02 AM
I'll have to disagree & say not only will you be happy, you'll have a grin every time you press the go pedal.:icon_thumby:

fastpakr
07-27-2009, 12:53 PM
A cam, depending on grind, may significantly change power characteristics to improve horsepower by pushing the peak torque point further out on the tach. It's not going to magically increase cylinder filling at low revs though, which is what the OP appears to want. Corrected gearing or forced air will do that.

Tee Rev
07-27-2009, 01:32 PM
A cam, depending on grind, may significantly change power characteristics to improve horsepower by pushing the peak torque point further out on the tach. It's not going to magically increase cylinder filling at low revs though, which is what the OP appears to want. Corrected gearing or forced air will do that.


This would be true if the factory cam was already allowing the maximum volumetric efficiency of said engine.

In this case the factory short duration low lift cam along with small valves hinder VE throughout the rpm range. A stock 4.0l will fall flat over 4500rpm.

Because of this, the comp 422 cam's longer duration & lift has the effect of increasing the VE of the 4.0l throughout the entire rpm band until the poor flow characteristics of the 4.0L's small valved heads come into play.

What you'll end up with, a 4.0L that has a substantial increase in torque off idle until the 5300 rpm redline.

Bob Ayers
07-27-2009, 01:49 PM
This would be true if the factory cam was already allowing the maximum volumetric efficiency of said engine.

In this case the factory short duration low lift cam along with small valves hinder VE throughout the rpm range. A stock 4.0l will fall flat over 4500rpm.

Because of this, the comp 422 cam's longer duration & lift has the effect of increasing the VE of the 4.0l throughout the entire rpm band until the poor flow characteristics of the 4.0L's small valved heads come into play.

What you'll end up with, a 4.0L that has a substantial increase in torque off idle until the 5300 rpm redline.

WRONG!

You are going to loose low end torque with the longer duration, but pick up
high end HP. The only way to pick up both is with VVT.

Tee Rev
07-27-2009, 02:05 PM
WRONG!

You are going to loose low end torque with the longer duration, but pick up
high end HP. The only way to pick up both is with VVT.

Just for giggles I'll post this again. But a little bigger so you actually read it.

This would be true if the factory cam was already allowing the maximum volumetric efficiency of said engine.

Bob Ayers
07-27-2009, 02:12 PM
Just for giggles I'll post this again. But a little bigger so you actually read it.

This would be true if the factory cam was already allowing the maximum volumetric efficiency of said engine.


Giggles is the operative word!!!:headbang::headbang:

Tee Rev
07-27-2009, 03:16 PM
Bob, Please don't ever PM me again. & if you have such a strong understanding of the formula for Volumetric efficiency. I challenge you to prove me wrong.

But remember one thing. I've built many engines in my career including the OHV 4.0L using the Comp 422 cam & each has exhibited the exact power increase that I've described.

As a true Ranger enthusiast I'm only trying to answer a question posted by dparkguy & I have practical knowledge on the subject.


If you feel that you have something constructive to add be my guest.

Will
07-27-2009, 05:16 PM
I'm not going to recommend changing a cam to pick up low rpm torque in order to make up for incorrect gearing.

Calculating MEP at the peak torque number the 4.0 comes in at 139psi. A 305hp/335ft# LT1 Z28 comes in at 144psi--similar technologies and definately built with VE in mind I would think. A 4.3 GM comes in at 150psi. The '03 (no VVT) Dodge Hemi is at 164psi. It's possible you could install headers, clean up the ports and such and get the pushrod 4.0 up there to 250ft# with the same shape of curve. But that's only a 12% gain and the proper gears for his truck would be 4.56s and they guarentee him about 22% more torque. A VVT, 4-valve 4.0 would be up around 190psi--300ft# or so. Even then, it's not the same as having the right gears. It will still be in the 200ft# range at 1,000rpm because it doesn't matter what you have for VE at 1,000rpm. And those 33s are going to dog it out when the clutch comes up.

I've never modified a 4.0, but my instincts tell me that he's better off spending his money on gears, even if there are some gains possible at low rpm that won't move the powerband up. I guarentee with 33s on 4.56s he'll be happier than a camshaft and 3.73s with his 33s. Definately I would consider doing engine work after the gear change.

Tee Rev
07-27-2009, 06:58 PM
I want to replace the stock cam with one that provides better torque. I have 5 speed with 33" tires, stock 3.73 gears. I don't want to upgrade gears yet. Will a different cam make me happy?

When I read this, I can see that a gear change is already planned. The question is in regards to a different cam.

Having real world experience with a lightly modified 4.0L I can honestly answer the actual question.

I've run this engine combination with 3.08's, 3.55's & 4.10's, all with 26" tall tires. On the street, With the 4.10's anything more than 1/4 throttle in first results in tire smoke and a quick shift into second will keep it going. Even with the 3.55's a spirited launch has the same result. Now with the 3.08's (pretty close to 3.73's with 33's) and a soft launch there was more than enough torque to get moving quickly without even coming close to bogging the engine. (With a 4x4 in low range, not an issue.)
I can honestly say that the 4.0L should have come with this cam in the first place!!

Now, since I drag race the truck, of course I run the 4.10's & slicks for traction, and I'll admit, gears with this combo will definitely keep you smiling for as long as you own the truck!!:icon_thumby:

AllanD
07-27-2009, 08:51 PM
a cam change will increase the RPM at which the torque will occour

There is No "down" to gain because the 4.0 OHV is already making
>190ftlb at 1000rpm.

NONE of the aftermarket cams increase bottom end, they move the torque
higher in the rpm band to make more power and none of that is going to
cure the fact that the OP has THE WRONG GEARS now.

He doesn't want to upgrade gears but spending easily twice as much
to install an aftermarket cam is practical? Ahhh... No.

IMO proper gearing to go with a 4.0 is as follows:
a 2wd 4.0 with 215/70-15's? 3.55
a 4x4 4.0 with 235/75-15's? 3.73
a 4x4 4.0 with 31x10.5-15? 4.10

with 33's? 4.56's would be about right...

Swapping a cam to avoid changing to the correct gears?
simply not going to do it for him.


AD

Will
07-27-2009, 10:09 PM
Alright Tee Rev, I made sure not to attack you while differing with your opinion. I consider your bolds and italics somewhat pointed and insulting. And they definately are not evidence--just word enhancements.

3.08s with 26" tires is the same as 33" tires with 3.90s. 26" tires with 4.10s is 5.20 gears and yes, my stock 4.0 would destroy tires with 5.20 gears on it. The 4.0 is a good engine without doing anything to it.

Competition Cams uses a 350 chevy to designs cams and then grinds them on blanks for everything else. They didn't put a 4.0 on the dyno and make a magic cam. Ford did though. They didn't do what CC did and pull a grind out of a generic box and slap it on the blank. They had that engine on the dyno for a year trying differnet things so it would pass the EPA sniffer and mileage requirements while also keeping an eye out for competitive power figures and drivability. All engines from the factory are tunes to make low end power. That's where people drive. The VE of a factory engine is maximized where you actually use it. They do studies to see where people drive and then maximize it right there.

You have a truck you are claiming low 14s without enhancements. A stock 4.0 from 1991 was rated at 155hp, net. A 3,000# Ranger would require 275hp net to acheive that. If you are using the CC 270HR grind in that motor, and those heavy lifters aren't jumping off the lobes by 5,500rpm, you have a BMEP of 162psi. The 207hp SOHC 4.0 is at 127psi (why did they bother, they should have called you!) and I'm trying to find something close to your 4.0 and can't do it. You are competitive with the 1995 Saab 900 turbo and the 2000 Porsche 911 non-turbo is a little higher.

All from the iron headed 2-valve (smaller valves than the 2.9--you should work with that engine, probably be ruuning it at Indy) Ford 4.0--which Ford erroneously replaced with cammer heads trying to get power out of it to compete with everyone else.

wahlstrom1
07-27-2009, 11:22 PM
While I can appreciate both school's of thought, more power vs. more gear the OP has said he doesn't want to do gears at this time. I have known Tee Rev (not a newbie) for several years and can say his truck flat out moves. I have seen dynograph's for his engine, and if I could link them I would, but here's the results (intake porting and headers as well)

The engine produced 198 ft/lbs @ 1700 rpm and gradually climbed to a peak of 219 @ 3510 rpm. Torque does not fall below 200 ft/lbs till 4700 rpm

Peak horspower was 181 @ 4760 rpm, and the engine exceeded 170 hp from 4300 rpm to 5340 rpm. And at 5560 rpm (end of the test) the engine was still at 161 hp.

Will the cam make a difference? YES

Will gears make a difference? YES

I say let him decide what he wants to do. He might be happy with 4.56's and 33's now, but decide to go 35" or bigger later and want more gear. The cam will help in the mean time, and it'll help later as well.....

fastpakr
07-27-2009, 11:24 PM
Those numbers sound remarkably like a typical OHV 4.0 with peak airflow point moved up 500-1000rpm, as Will, AllanD, and myself suggested. Quite the opposite of what the OP appears to need. Not that a cam is a bad change, but it does nothing to improve low RPM airflow.

wahlstrom1
07-27-2009, 11:44 PM
Should have pointed out.....Those numbers are RWHP/TQ numbers on a mustang dyno, long bed 2wd 5 spd

1/4 mile times:

(Best N/A #'s) ET 14.304 @ 90.74 mph / MPH 94.8 / 60' 1.851 sec.

(Best on the bottle) ET 13.427 @ 100.78 / MPH 100.8/ 60' 1.933 sec.

Bob Ayers
07-28-2009, 06:01 AM
From Ford.........................


http://bob-ayers.smugmug.com/photos/358158961_kNPCN-X2.jpg

AllanD
07-28-2009, 12:36 PM
Those numbers sound remarkably like a typical OHV 4.0 with peak airflow point moved up 500-1000rpm, as Will, AllanD, and myself suggested. Quite the opposite of what the OP appears to need. Not that a cam is a bad change, but it does nothing to improve low RPM airflow.

Like I said THE SAME torque just at a higher rpm and considering it's a truck with too tall gears or too tall tires for the gears the SAME torque at a HIGHER rpm will do NOTHING to make the situation better infact it'll exaggerate the situation that the OP is already complaining about.

So Once again, another cam will NOT "make him happy"

it WILL make the situation worse.

And I'm gettin' tired of having to repeat myself to people who have
their little idea but refuse to listen to simple physical reality.

So I'm terribly NOT sorry to confuse anyone with facts.



AD

Tee Rev
07-28-2009, 01:14 PM
You guys kill me!!:icon_rofl:

The #'s Andrew posted are at the wheel, not at the crank. I'll let the mathematicians figure out the Crank #'s :icon_rofl:


I'll keep my advice to PM's from now on, you guys are just too much!:icon_confused:

Bob Ayers
07-28-2009, 01:16 PM
Like I said THE SAME torque just at a higher rpm and considering it's a truck with too tall gears or too tall tires for the gears the SAME torque at a HIGHER rpm will do NOTHING to make the situation better infact it'll exaggerate the situation that the OP is already complaining about.

So Once again, another cam will NOT "make him happy"

it WILL make the situation worse.

And I'm gettin' tired of having to repeat myself to people who have
their little idea but refuse to listen to simple physical reality.

So I'm terribly NOT sorry to confuse anyone with facts.



AD


Must be a Canadian thing!!!:icon_hornsup::icon_hornsup:

fastpakr
07-28-2009, 01:19 PM
You guys kill me!!:icon_rofl:

The #'s Andrew posted are at the wheel, not at the crank. I'll let the mathematicians figure out the Crank #'s :icon_rofl:


I'll keep my advice to PM's from now on, you guys are just too much!:icon_confused:

I don't think anybody confused the two. Obviously those are wheel numbers. The point is that you're now making your peak numbers well AFTER the factory 4.0 did. Instead of helping the problem of low end torque, you've made it worse. Your own numbers clearly demonstrate that. Not sure where the confusion lies.

Bob Ayers
07-28-2009, 01:22 PM
I'll let the mathematicians figure out the Crank

Yes, you seem to have trouble with basic math!!!!!:headbang:

Tee Rev
07-28-2009, 02:19 PM
I don't think anybody confused the two. Obviously those are wheel numbers. The point is that you're now making your peak numbers well AFTER the factory 4.0 did. Instead of helping the problem of low end torque, you've made it worse. Your own numbers clearly demonstrate that. Not sure where the confusion lies.

Really!!:icon_confused:

Assuming a conservative 15% loss through the drive line, 198 rwtq at 1700 = 232.9 ft/lbs at the crank. 219 rwtq at 3510 = 257.6 ft/lbs at the crank.


Can you please show me where I hurt low end torque? :icon_confused:



BTW Bob, you may want to keep your comments to yourself! I've probably got more American heritage than you!! Scary isn't it! :icon_thumby:

fastpakr
07-28-2009, 02:31 PM
15% isn't remotely 'conservative'. While it may be common place to make up convenient numbers to explain driveline loss, that's a tremendous amount of power to vanish into heat.

Even assuming 15% is accurate, go look where the factory 4.0 was at 1700RPM. North of 220. As good, if not better than yours. You have not improved low end torque in the slightest. You do have slightly better numbers on the top end, but again - that is not what the OP is looking for.



***** Both you and Bob need to stop the insults. Consider yourselves warned. Keep this a tech discussion. ****

wahlstrom1
07-28-2009, 08:40 PM
Even if he is only making stock power at lower RPM, the higher rpm torque will pull harder on the under geared vehicle as you'll be pulling the same rpm's longer due to the effectively higher ratio. IMO is it the ideal setup? No....gear's rock! But it can't hurt, I know when I had the OP's setup I wish I had more power in the high end because I spent a lot more time the due to the gearing issues.

AllanD
07-28-2009, 10:21 PM
Even if he is only making stock power at lower RPM, the higher rpm torque will pull harder on the under geared vehicle as you'll be pulling the same rpm's longer due to the effectively higher ratio. IMO is it the ideal setup? No....gear's rock! But it can't hurt, I know when I had the OP's setup I wish I had more power in the high end because I spent a lot more time the due to the gearing issues.

Once you get it rolling and into the torque band, yes.

the rub is we are discussing 4x4 trucks and torque below the peak
is VERY important particularly when offroading.

I'm highly concerned with power in that part of the torque band,
not because I offroad, but because I drive more miles towing in
a year than most people here do commuting each month.

Offroading is subject to the same needs.

But torque way down low is less about acceleration than it is about precise control of the vehicle going over obstacles.

Did you ever have a boat that took FOREVER to get up on plane
but once it was there it was "fine", frankly unless you got laid in that boat you probably don't have fond memories of it.

AD

Will
07-28-2009, 10:47 PM
That's a quick 91mph. A more usual low 14 (I used a 14.2 when I entered it into my super-secret VBasic program) would be 100mph. 91mph is 200hp net and a typical 3000# car would run a mid 15s. Completely believable. The truck is set up exceptionally well.

Otherwise, I completely agree with Fastpakr and AllanD in this. Gear the truck properly. Showing me 197ft# at 1700rpm--and giving you the 15% benefit of the doubt--you are still pretty much on the stock Ranger torque curve. And a stock Ranger 4.0 with 3.73s sux with 33" tires.

Tee Rev
07-29-2009, 09:21 AM
Thanks Will, I attribute the low mph to the brick like shape of my truck.
If you run the 1/8th mile #'s through your program you'll see a slight increase (9.03 @ 76 mph) & although I have managed to run back to back 14.37's @ 95 mph, usually the mph is 91-92 :dunno:
Something else to take into consideration is the effective altitude. In Calgary The effective altitude can range from 4500' to 6500', at these altitudes the engine is only able to produce 85- 90% of it's power. 200hp here would be at the very least 220 at sea level.

Also, I'm not in disagreement about the gear issue at all. As a matter of fact, I have an 06 R/C 4.0L 4x4 that has 31's & 3.73's that I'm installing 4.56's in as soon as possible. It probably doesn't need them, but I know that bigger tires are in it's future

My intention was only to answer what I read as the question.

But I do have something to add,

Regarding the driveline loss; Friction is only part of it, the mass of the driveline is also a factor. There's close to 300#'s that link the flywheel to the rollers on the dyno(transmission, diff & wheels), Considering that the test only lasts a few seconds, it takes a considerable amount of power to accelerate this mass through the test range. The power required to do this isn't going to make it to the rollers on the dyno, & therefore is lost.

No convenient numbers, just simple physics.


AllanD is concerned with possible drivability issues with this cam. You definitely don't want a cam that has a tendency to make the engine surge while you're trying to tippy toe through rocky terrain. The 422 is a very mild grind, it still pulls 20 in/hg of vacuum at an idle of 750rpm & has only the slightest lope. By 1000rpm under very light throttle it pulls 23 in/hg of vacuum & is absolutely smooth.

Here is a link to a video of me doing a couple 1/4 mile test runs on a dyno shortly after swapping the cam. This is with the factory ECU & stock program.

Enjoy!:icon_thumby:
http://members.shaw.ca/tomak/quartmile.wmv

AllanD
07-29-2009, 01:39 PM
Regarding the driveline loss; Friction is only part of it, the mass of the driveline is also a factor. There's close to 300#'s that link the flywheel to the rollers on the dyno(transmission, diff & wheels), Considering that the test only lasts a few seconds, it takes a considerable amount of power to accelerate this mass through the test range. The power required to do this isn't going to make it to the rollers on the dyno, & therefore is lost.

No convenient numbers, just simple physics.


Just simple physics? Yeah, that you have an incomplete grasp of.

No power is actually "lost" through driveline mass, however it affects the measurement of the power precisely as you describe.
But the power didn't actually go anywhere.

and the apparrent loss isn't nearly as great as you think it is.

you've probably been misled by others talking up their stuff the same way.

Just between you and me the picking at your posts isn't nearly what it would be if you have waved a "red flag" like saying (for example) that you had a "3/4 race camshaft" try that one sometime and the fecal material will really splatter as it hits the rotary ventilation device.

AD

colinrmitchell
07-29-2009, 02:53 PM
http://www.genx40.com/images/2006/ein70654.jpg
"It just doesn't work out!"

Tee Rev
07-29-2009, 04:33 PM
Just simple physics? Yeah, that you have an incomplete grasp of.

No power is actually "lost" through driveline mass, however it affects the measurement of the power precisely as you describe.
But the power didn't actually go anywhere.

and the apparrent loss isn't nearly as great as you think it is.

you've probably been misled by others talking up their stuff the same way.

Just between you and me the picking at your posts isn't nearly what it would be if you have waved a "red flag" like saying (for example) that you had a "3/4 race camshaft" try that one sometime and the fecal material will really splatter as it hits the rotary ventilation device.

AD

Strange, I try to be nice & you decide to be rude? :icon_thumby: Good on ya ...

I must have managed to touch a nerve if you've decided that insults will help you prove a point!

You're also now using semantics to prove a non existent point. & you're incorrect.

If this were a step test where the engine was stabilized & loaded at set rpm points to take the measurement, the driveline mass wouldn't be an issue, only frictional losses would. The measured values would reflect this.

But this is an acceleration test, power is required to accelerate the mass of the driveline & the power used won't be measured. As a result this test will show lower figures. Or a "loss" (oh heaven forbid .... I used that word!!:shok:)

To say the power didn't actually go anywhere is flat out wrong, it was used to accelerate the driveline.

So what exactly is the point you're trying to make?

Oh ya .... I remember ... I have an incomplete grasp of simple physics .... right!!:icon_thumby:

AllanD
07-29-2009, 05:57 PM
Ok, where exactly was I rude?
Certainly not my intent but that can so easily change....
don't ASSume the "tone" of words of someone you don't know that well.

Not to mention that the entire rotating weight comes nowhere close to 300lbs.
200lbs would be debatable

People who actually measure and calculate things generally react poorly to
rectally derived figuires.

It "seems to" when you "measure" it on a DynoJet, but "seems to"
and "Does" are two entirely different things.

That's where your grasp of physics falls flat.
And don't argue measurement with a trained metrologist.

The power is still there, but power measurement during acceleration
is from the beginning a fundementally flawed way of measuring power.

THAT is where YOUR grasp of physics falls flat.

people who really want to know power don't test claimed power
by dynometer, but by weighing the car then taking the car out onto
a FLAT test track and measureing the actual coastdown drag
THEN measuring the car's acceleration and top speed.

in BOTH directions to remove the factor of wind direction.

this test method is unambiguous...

AD

Yellowsplash
07-29-2009, 10:26 PM
I run 33s on 3.73s and manual tranny and from my personal experience and opinion, I agree that gears are much more important than a cam at this point. As said earlier, 4.56 gears would transfer much more of the torque you are needing to the ground. The problem with 33s and 3.73s is that while it might not be bad on a straight stretch of road to get into your power curve, on any type of incline it becomes a struggle. Overcoming heavy tire and wheel combos are much tougher than on a 26" wheel with 3.08 gears....you cant compare the two because its not the same. The numbers might be close on paper, but if you've ever driven a truck with this combo, you would understand. Swap the gears and fall in love with your truck all over again....and enjoy the better gas mileage.