Low speed torque and driveability ?

[a-bodyguy]

The whole thing I'm getting at is torque the main/whole culprit ? As most would say or is there other factors that play a huge or bigger role ?

Obviously what we consider driveability and what part of driving has a huge effect, cruising, passing, spirted driving, from stop to full throttle and cruising to full throttle are all different in what were exactly comparing.

Like you said earlier you find a xe268h cam a dog compared to stock 340 cam, your saying cause of loss of torque, I'm saying maybe, maybe part of it but I don't think so, all those dyno's I posted low end torque don't seem to be an issue, but were generally not seeing under 2000-3000 rpms so hard to say for sure, but if there is an issue I'd say it's probably other things which I was hoping to get to the bottom of.

If it is mainly a lack of torque that would be fine I just don't see how.

P.S. Aj say 340 cams have terrible bottom end


An engine needs very little hp most of the time.

At 1313 rpm hp is 25% of torque.

Tq. hp.
100 = 25
200 = 50
250 = 63
275 = 69
300 = 75
325 = 81
350 = 88

At 2626 rpm an engine need half the torque to make those hp numbers.

wtf does 1500 or 1800 have to do with anything?
the lowest stall is 1800 you are there for a milisecond
I could cruise my 243@50 cam no problem 1800 in drive 3.23s 26.99 L-60-14 stock verter

People need to learn how to tune

 

[Hysteric]

I'd say it's a case of piss poor carb parts selection and tuning.

Neither of those.

 

[Dave999]

Ive dipped in an out through out of the thread i aint read it all sorry...

torque, measurable physical unit
diveability emotive description of function of car on the street


350 ftlb or torque at 300 rpm
280 at at readline of 700 rpm

Ok that's a1930s 20 litre diesel tug-boat motor

drivability with a 3 speed box would be quite poor. unless its a road roller. or a tractor for moving the space shuttle to the launch pad.
You'd have no problem setting off in any gear but its gonna take a very long time to get there and and your MPG will be awful.

drivability with a 16 or 20 speed box might be quite good if you could put up with changing gear.

torque curve and the correct gearing for the job in hand. The aim? getting to walmart at a brisk pace... or getting to the end of the track as fast as possible

OK now we can say something about drivability... and it would be
My gearing is perfectly matched to the characteristics of my engine in an RPM range that seems reasonable for the application

if the car is designed to drag race you can't be complaining about drivaility on the street
street driving was not the application

If you street drive and your performance improvements all come out of the drag racing box
maybe that wasn't a performance improvement, it cost the same as a performance improvement, that someone might do to a drag car, but didn't improve performance for your application...

poor drivability

Dave

 

[Newbomb Turk]

Neither of those.

Yeah, it is. If you have to use heat to get your fuel atomized and vaporized you ain’t doing it right.

Adding heat is always the worst option to make power.

Basic **** if YOU ever did ANY testing of your own.

 

[273]

Yeah, it is. If you have to use heat to get your fuel atomized and vaporized you ain’t doing it right.

Is there a huge amount of power to be gain say from average guy decent tune say edelbrock top end 360 to something Hysteric thinks people should build in the same vein for optimal fuel atomization and vaporization ?

 

[Newbomb Turk]

Is there a huge amount of power to be gain say from average guy decent tune say edelbrock top end 360 to something Hysteric thinks people should build in the same vein for optimal fuel atomization and vaporization ?

He has a different way of going about it. I’ve never been a fan of hot engines and hot air. It today’s pump fuel is a bear to even vaporize so sometimes heat may be required. For me heat is a last resort.

 

[sireland67]

You probably never looked up how to calculate horsepower. You can put your car on a chassis dyno and that gives you rear wheel horsepower only ( at least that's what they only show when they test your car's power, I've never heard of them giving flywheel horsepower on a chassis dyno.

My neighbor ran his truck on a chassis dyno, the print out gave to him said this.

Torque 650.62 ft/lbs
HP 702.63
Crank hp 872.79

So this is the first chassis dyno print out I have seen, just contradicted everything you said.

 

[Hysteric]

Yeah, it is. If you have to use heat to get your fuel atomized and vaporized you ain’t doing it right.

Adding heat is always the worst option to make power.

Basic **** if YOU ever did ANY testing of your own.

You think you did more testing than Shrinker?

 

[Dan the man]

My neighbor ran his truck on a chassis dyno, the print out gave to him said this.

Torque 650.62 ft/lbs
HP 702.63
Crank hp 872.79

So this is the first chassis dyno print out I have seen, just contradicted everything you said.

Not really, if you use the calculation of .80 for a automatic is actually pretty close.

 

[Newbomb Turk]

You think you did more testing than Shrinker?

I never said that. And I don’t care what his testing is any more than he would care about my testing.

What I do know is I post what MY testing shows. You post what other people do.

 

[Newbomb Turk]

Not really, if you use the calculation of .80 for a automatic is actually pretty close.

Not really. That’s almost 25% loss. Which is expected with a truck.


So your 25% is off the majority of the time.

In fact, I can change tire pressure and gain or lose a couple of percent.

 

[Dan the man]

Not really. That’s almost 25% loss. Which is expected with a truck.


So your 25% is off the majority of the time.

In fact, I can change tire pressure and gain or lose a couple of percent.

I was only using it as a guideline. If you take the claimed flywheel horsepower and multiple it by .80 it's pretty close to what he said that the rear wheel horsepower is. How do you gap your spark plugs, are you sure that the gap is a 100% correct? If your not using a gauge that's been done at a machine shop instead of a product gauge then that's off to. I'm not perfect here

 

[Newbomb Turk]

I was only using it as a guideline. If you take the claimed flywheel horsepower and multiple it by .80 it's pretty close to what he said that the rear wheel horsepower is. How do you gap your spark plugs, are you sure that the gap is a 100% correct? If your not using a gauge that's been done at a machine shop instead of a product gauge then that's off to. I'm not perfect here

No one is asking you to be perfect. Just asking you to realize that posting any number for converting wheel power to crank power is at best a guess.

 

[Dan the man]

No one is asking you to be perfect. Just asking you to realize that posting any number for converting wheel power to crank power is at best a guess.

Very true. It's just that no matter what I post some on here make a big deal out of it

 

[273]

No one is asking you to be perfect. Just asking you to realize that posting any number for converting wheel power to crank power is at best a guess.

What I don't get is, doesn't take X amount of hp to turn a trans, rear end, tire etc.. Shouldn't take a similar amount of power loss at similar rpm (not a percentage), be it a 300 hp engine vs 600 hp engine ?

 

[Dan the man]

What I don't get is doesn't take X amount of hp to turn a trans, rear end, tire etc.. Shouldn't take a similar amount of power loss at similar rpm (not a percentage), be it a 300 hp engine vs 600 hp engine ?

I don't know how they come up with those calculations. All I know is that for years people would say that there's a 15% - 25% power loss from the flywheel to the rear wheels and where the .80 for automatic transmission and the .85 for a manual transmission came from. If you take the horsepower that they got and x it by .80 it's pretty close to the wheel horsepower. I know that there are lots of variables here and I understand that. I'm just saying that I'm tired of always being told that either I'm wrong or I don't know what I'm talking about. If I'm wrong please correct me but I wish that it would be done in a more respectful manner. Thanks

 

[a-bodyguy]

I don't know how they come up with those calculations. All I know is that for years people would say that there's a 15% - 25% power loss from the flywheel to the rear wheels and where the .80 for automatic transmission and the .85 for a manual transmission came from. If you take the horsepower that they got and x it by .80 it's pretty close to the wheel horsepower. I know that there are lots of variables here and I understand that. I'm just saying that I'm tired of always being told that either I'm wrong or I don't know what I'm talking about. If I'm wrong please correct me but I wish that it would be done in a more respectful manner. Thanks

Its less for a manual Dan quit while your behind
You do not have a clue
What did rumble say oh yes no offense Dan stfu already move on

 

[Dan the man]

Its less for a manual Dan quit while your behind
You do not have a clue
What did rumble say oh yes no offense Dan stfu already move on

I know you know more than the people who do the research. Do yourself a favor, take the horsepower that he said he got at the flywheel and times it by .80 and then times it by .85 and you'll see what I mean. I'm not saying that it's right or wrong. But if you do this you'll see that the .80 gets close to his rear tire horsepower. Maybe it's because that someone knows something that you don't. I can tell by your reply that your going about this with a closed mind

 

[ir3333]

maybe it was explained a little yonkey.
I think he is saying losses on an automatic leave .80 at the rear wheels
losses for a manual leave .85 at the rear wheels.

 

[Newbomb Turk]

What I don't get is, doesn't take X amount of hp to turn a trans, rear end, tire etc.. Shouldn't take a similar amount of power loss at similar rpm (not a percentage), be it a 300 hp engine vs 600 hp engine ?

I wish it was that easy. But it’s not. Friction increases with RPM and MPH.


And like I said before, unless you do a coast down on every vehicle you don’t have a clue what it takes to run the drive train.

There are some exceptions to that. One being if you have a dedicated dyno car. In that case, you are using the same car, same transmission, same rear axle so the percentage will be the same every time.

 

[fishmens67]

One being if you have a dedicated dyno car. In that case, you are using the same car, same transmission, same rear axle so the percentage

Convertor slippage could play a factor depending on engine combo.

 

[273]

Here's a mild /6 makes 185 lbs-ft @ 2600 rpm and below the 380hp crate engine that should have stall and gears to be streetable but making 380 lbs-ft @ 2500 rpm about 200 lbs-ft more than the /6.
Even though were not seeing under 2500/2600 rpms I doubt anyone can make the argument the 360 will make less torque than the /6 at any rpm.

If torque was the culprit no way a \6 would be streetable, slow yes but unstreetable no.

Mopar Performance 360 cid 380 hp rated

RPM	TQ	HP
2500	380.6	181
3000	402.9	230
3500	415.1	277
4000	437.8	333
4100	439.5	343
4500	437.1	375
5000	416.3	396
5400	398.6	409
5500	388.6	407
6000	343.9	395

 

[ir3333]

I don't actually know but have "read" long duration cams have very poor cylinder filling and mixing, are
inefficient and make very little power at lo rpm.
That broken idle that most guys love is actually raw gas burning and exploding in the exhaust system.
Maybe it's not the torque number but just poor performance created by a long duration cam at lo rpm.

 

[273]

I don't actually know but have "read" long duration cams have very poor cylinder filling and mixing, are
inefficient and make very little power at lo rpm.

I've always heard and thought the same but now questioning it.

That broken idle that most guys love is actually raw gas burning and exploding in the exhaust system.
Maybe it's not the torque number but just poor performance created by a long duration cam at lo rpm.

Idk but I'm thinking overlap is probably the main culprit not necessarily loss of torque cause if an engine doesn't like to idle at low rpms it probably don't like to drive at those rpms too. I'm thinking if there's lesser torque is more of a correlation than causation. But I could be wrong still trying to work it out.

 

[273]

Plus I'm questioning that big cam have poor low speed torque, now obviously we've all seen bigger cams give up torque to smaller cams but when put in perspective and especially vs a stock low powered 2bbl version of the engine bigger cams still seem to do decently down low, obviously we generally don't know what's going on under 2000 rpm.

Here's a dyno of a stock 2bbl cam to xe262h cam among other mods, as you can see all doing decent down to 2000 rpms, the one below doing well under 3000 rpms would have to look the cams up but are 390-430 hp 360, cams must be fairly decent and Richard Holdener dyno of a stock 2bbl 360 engine dyno'd 330 lbs-ft @ 2000-3000 rpm and the 380hp crate from my other post doing better than all at 381 tq @ 2500 rpm.

And the bunch of 318/340 dyno's with various cam all making decent 2000-3000 rpm torque numbers from what we can tell.

I'm just not seeing big torque drops were you could say that's why driveability suck and gonna need stall and gears to get her to be able to pull away from a stop sign, especially when there making way more torque than a stock /6 273 318 even 2bbl 360.

Torque
RPM	1	2	3	4	5	6
2000	357.3	376.9	346.7	356.8		349.6
2200	350.7	370.9	347.9	351.3		345.8
2400	349.8	367.5	355.9	353.1		350.4
2600	351.5	367.1	359.5	352.6	361.0	353.8
2800	358.8	374.1	367.1	357.7	359.7	361.0
3000	370.1	388.0	373.6	363.2	364.1	371.9
3100	371.7	390.6	375.9	366.0	369.3	375.6
3200	371.2	390.7	376.0	368.7	375.7	381.6
3300	371.3	390.3	377.1	368.8	381.0	389.6
3400	367.8	388.9	374.1	368.7	386.3	396.1
3600	361.2	381.7	369.2	367.0	390.8	400.1
3700	357.7	375.0	367.1	363.3	391.8	400.6
3800	349.9	370.4	363.6	358.7	386.9	398.0
4000	342.8	357.8	354.9	348.3	380.3	394.0
4200	331.0	346.3	344.9	337.6	383.1	389.5
4400	316.4	329.1	329.0	325.1	378.1	385.5
4600	295.7	311.0	313.3	310.5	368.2	375.6
4800	286.5	293.8	299.8	290.7	355.1	363.3
5000	270.9	278.7	282.0	272.4	342.7	351.9
5200		330.3	337.8
5400	311.8	321.7

360 build

Dyno Test
Horsepower				Torque
RPM	Test 1	Test 2	Test 3	RPM	Test 1	Test 2	Test 3
2600	172.7	N/A	166.1	2600	348.9	N/A	335.6
2800	190.6	196.6	183.9	2800	357.7	365.8	345.1
3000	204.3	207.5	197	3000	357.7	363.3	345
3200	190.1	226	216.2	3200	359.6	370.7	354.9
3400	237.6	242.4	235.3	3400	367	374.5	363.5
3600	258.3	267.7	253.1	3600	376.8	390.6	369.3
3800	281.4	281.8	274.9	3800	388.9	389.4	379.9
4000	299.6	310.1	297.1	4000	393.5	407.2	390
4200	319.1	313.8	314.4	4200	399.1	392.3	393
4400	320.8	329.4	328.5	4400	383.8	393.1	392
4600	354.5	352.7	352	4600	404.8	402.7	401.6
4800	359.5	379.4	375.4	4700	397.2	420.2	408.4
5000	377.4	392.3	389.4	4800	393.4	415.2	410.7
5200	378.8	396.5	401.6	4900	399.8	410.6	412.2
5400	390.3	401	411.7	5000	396.4	412	409.1
5600	384	399.1	420	5200	382.6	400.4	405.7
5800	387	392.3	426.5	5400	379.5	390	400.5
6000	369.2	391.8	430.2	5600	360.2	374.3	394
6200	370.2	377	423.3	5800	350.5	355.3	386.1