3.7 vs. CRD

KJ 119 · **Posted:** Sat Jul 18, 2009 12:02 pm

A few weeks ago I did a 40mph punch with Hood297,and was surprised to see him end up in my rear view mirror.
We both have aftermarket steel bumpers,winch,rockrails,full skids(including prerunner),lifted,and I believe we both have
373's(not sure if hood has 410's,don't think so).
With more HP,why didn't he dust me?Was it the tranny?
Next time I'm around Hood,I'll buck him up to run'em from a dead stop.
Anyone else run a 3.7?

gmctd · **Posted:** Sat Jul 18, 2009 12:44 pm

How big is his turbo?.....................

Fulltimer · **Posted:** Sat Jul 18, 2009 12:49 pm

Hmmm, I was thinking the 3.7L had more HP & less torque than the CRD. Hook up to 1,000lbs. and have a race and see what happens! :lol:

Terry

chrispitude · **Posted:** Sat Jul 18, 2009 1:20 pm

Fulltimer wrote:

Hmmm, I was thinking the 3.7L had more HP & less torque than the CRD. Hook up to 1,000lbs. and have a race and see what happens! :lol:

Or better yet, 5000lbs!

I do wonder if he would have eventually had you, given the top-end of a gasser motor.

- Chris

Pablo · **Joined:** Thu Feb 02, 2006 10:06 pm **Posts:** 1201

Was he really flogging the 3.7? Peak power output is way up high around 5200 RPM. Most do not rev their engines that high, and with the newer motors-- there is not much power down low. When cruising, the gasser is no where near its peak power curve and it will take the transmission some time to downshift and then the engine will take some more time to build up RPM to get into the powerband. The greater the load, or the less torque applied to the load, the longer it takes for the engine RPM to increase. That means a fat Jeep is going to take longer to build a head of steam with less torque than it will with more torque, even more so when in a higher gear (like cruising along at 40 MPH). So while the gasser has more HP (steam), it can take longer at certain speeds and loads to get the steam built up due to the lack of immediate torque available.

With the CRD, your turbo is sitting there ready to go, so even though you only have 160 hp-- you have access to it more or less instantly when you are in between your peak torque and horsepower (1800-3200 RPM).

If you repeat the result for a longer period of time than just stabbing the pedal, the gasser will catch and pass you, unless the gasser does not have the torque to reach the higher RPM and generate more HP (like going up a hill or towing a heavy load).

KJ 119 · **Posted:** Sat Jul 18, 2009 8:26 pm

gmctd wrote:

How big is his turbo?.....................

Yea guess that had something to do with it,but at no time did I think a CRD would take a gasser under any situation(other than towing).
Hood was the one to give me the(Wanna Run'em)look so I promise he had it floored. :roll:

The two lane road eventually turned into one,so I recon you guys are right.Had the road continued on two lanes
I'm, sure I would've eventually seen his backside. :shock:

flash7210 · **Posted:** Sat Jul 18, 2009 8:28 pm

Fulltimer wrote:

Hmmm, I was thinking the 3.7L had more HP & less torque than the CRD. Hook up to 1,000lbs. and have a race and see what happens! :lol:

Terry

Hey Terry!
Monday morning...
You, Me, at 207 Armory.
Drag race, 3.7 vs. CRD!

What do ya say... :wink:

Dave

Dave08 · **Joined:** Fri Nov 02, 2007 4:17 pm **Posts:** 250

Dad owns a CRD stock , I own a lifted 3.7. I can tell you his will do better UNLESS you give the 3.7 some RPM's ~4000+

geordi · **Posted:** Sat Jul 18, 2009 9:56 pm

And that has been the problem with the more recent engine designs for the gassers - You can't power an engine with a hamster wheel and expect ANY significant power from it until you wind it up to a ridiculous level... Which you won't do under most circumstances, so what you end up with is an underpowered and under performing system.

The time and fuel it takes to spin that engine to 5k rpm would be better spent on TORQUE which actually moves you. I had an 83 town car, with the 302 c.i. v8. That engine redlined at 4500 rpm... And for a 4500 lb BRICK of a car (with only a 4-speed transmission) it got upwards of 28mpg on the highway. It was a SLOW turning engine by comparison with today's cars, and barely was rated with 125 HP... But each one of those was a draft horse by comparison with today.

People market and buy HP, but they DRIVE torque.

CRD Joe · **Posted:** Sat Jul 18, 2009 10:05 pm

Enzo Ferrari used to say, "Horse power sells cars, torque wins races!"

The answer is easy. TORQUE!

tjkj2002 · **Posted:** Sat Jul 18, 2009 11:39 pm

Soon as my KJ is mobile again I'll race you,I'll also be about 2000lbs heavier and sitting on 35" tires,but I guarantee you wouldn't beat me since I'll be geared for more low end torque.

Properly gearing for the engine,weight,tires,and trans gear ratios makes a world of difference.

DarbyWalters · **Posted:** Sat Jul 18, 2009 11:49 pm

Right...will that Guarantee be in writing?

KJ 119 · **Posted:** Sat Jul 18, 2009 11:53 pm

tjkj2002 wrote:

Soon as my KJ is mobile again I'll race you,I'll also be about 2000lbs heavier and sitting on 35" tires,but I guarantee you wouldn't beat me since I'll be geared for more low end torque.

Properly gearing for the engine,weight,tires,and trans gear ratios makes a world of difference.

Only if it's for pinks,I think your rig would be worth the gamble.

Just saying that we were equal in all ways but the engine(including gears).
Now Hood had his girlfriend with him but she couldn't have weighed more than the extra battery,plus the diesel is a lil heavier.

geordi · **Posted:** Sat Jul 18, 2009 11:56 pm

Any Day, any road. I know the diesel will chew your gasser up and spit it back out.

tjkj2002 · **Posted:** Sat Jul 18, 2009 11:58 pm

KJ 119 wrote:

tjkj2002 wrote:

Soon as my KJ is mobile again I'll race you,I'll also be about 2000lbs heavier and sitting on 35" tires,but I guarantee you wouldn't beat me since I'll be geared for more low end torque.

Properly gearing for the engine,weight,tires,and trans gear ratios makes a world of difference.

Only if it's for pinks,I think your rig would be worth the gamble.

Just saying that we were equal in all ways but the engine(including gears).
Now Hood had his girlfriend with him but she couldn't have weighed more than the extra battery,plus the diesel is a lil heavier.

Isn't he running 32" tires still? With stock gearing those 32" tires make's his effect gear ratio pretty low,about 3:1 instead of 3.73:1 which is alot.

gmctd · **Posted:** Sun Jul 19, 2009 4:38 am

Hoo boy......gassers (patooie!) - hint:

a 3.7L engine pumps ~1gal of air per two crank revolutions (it is a four-stroke cycle implementation of an air pump) at one atmosphere (Baro) or 1 Bar - it will continue to do so up to redline, no matter how much fuel is poured into it - pity the poor gasser (....!)

a 2.8L engine pumps ~3/4gal of air per two crank revs (samo-samo) at 1 Bar - however, add a magic Bar increaser, and the smaller engine can pump ~5.6L of air per 2 crank revs at 2 Bar (Baro + 15psi Boost), or ~8.4L of air at 3 Bar (Baro + 30psi Boost)

Add fuel to suit, and it should become clear why a heavy 4wd 2500-series 5.9L TurboDiesel pick'em-up can blow the doors off a V10 Viper in the 1/4mi arena...................

Note: lower the numerical final drive ratio and add Firestone hi-speed tires and the 5.9L TurboDiesel pickup can set a world land speed record down, back and down of 222mph - howzat fer gettin' outta town?

(Figures are rounded for general demonstration - other factors may effect results - yrmvc - ask your doctor if your heart can stand the excitement - sildenafil citrate won't even help, here)

tjkj2002 · **Posted:** Sun Jul 19, 2009 8:40 am

gmctd wrote:

Hoo boy......gassers (patooie!) - hint:

a 3.7L engine pumps ~1gal of air per two crank revolutions (it is a four-stroke cycle implementation of an air pump) at one atmosphere (Baro) or 1 Bar - it will continue to do so up to redline, no matter how much fuel is poured into it - pity the poor gasser (....!)

a 2.8L engine pumps ~3/4gal of air per two crank revs (samo-samo) at 1 Bar - however, add a magic Bar increaser, and the smaller engine can pump ~5.6L of air per 2 crank revs at 2 Bar (Baro + 15psi Boost), or ~8.4L of air at 3 Bar (Baro + 30psi Boost)

Add fuel to suit, and it should become clear why a heavy 4wd 2500-series 5.9L TurboDiesel pick'em-up can blow the doors off a V10 Viper in the 1/4mi arena..................

Note: lower the numerical final drive ratio and add Firestone hi-speed tires and the 5.9L TurboDiesel pickup can set a world land speed record down, back and down of 222mph - howzat fer gettin' outta town?

(Figures are rounded for general demonstration - other factors may effect results - yrmvc - ask your doctor if your heart can stand the excitement - sildenafil citrate won't even help, here)

Might want to check your #'s,a stock 5.9 2500 is really slow in the 1/4 and 222mph+ has been achieved by stock gas vehicles.So 222mph in a heavily modified diesel is pretty lame,and how long did it take to get there? For 1/4 of the money you can get a gas V-8 to achieve that in 1320'.

jinstall · **Posted:** Sun Jul 19, 2009 9:48 am

Who cares if the 3.7 is faster in the 1320, lets see if it can get to 129mph and maintain it. I would like to see how far a 3.7 can get on a tank while running between 110-120 mph. What a 190 miles maybe?

CRD Joe · **Posted:** Sun Jul 19, 2009 12:22 pm

Well I dont know about the 3.7, though Im not a fan of gassers. I have four turbo diesels. At at stop light if I hammer the go peddle from a stop my truck will spin both tires on dry pavement for 40+ feet!

New tires too!

Will the gassers do that?

gmctd · **Posted:** Sun Jul 19, 2009 7:47 pm

And, that record-holder pick'em-up towed the parts and tires trailer ~2000mi to the flats, switched the street tires for the Firestones, ran the 3 flying miles, switched back to street tires, and towed the trailer and the record back home - Diesels...don't invite one over for lunch if ya don't want yer plate cleaned.....................

3.7 vs. CRD

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