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Tractor Pulling Discussion Forum

compression

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too much

02-21-2008 10:01:45




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How much compression is too much on a pulling tractor. I know with a lot you will have too run good gas , but can you get too much.




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ChadS

03-01-2008 14:30:54




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
Pedal faster darn it!!! LMAO!! Need to get you a new record,, cause yours seems to be skippin. You can get nasty if you want, but youll never, EVVVVER do what I can do. My dad is a good man, COME AND GET YOUR SPRING!!!!! Ill show you where you can stick it,,,, on your pedal tractor that is,,,, HAHAHA!! ChadS [email protected]



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ChadS

03-01-2008 04:19:29




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
I can count, exactly, how many times, Ive ever stalled Something Wilder durin the act of pulling. 4 times in 7 years, I have every time on film too!! 3 times at the NATPA Hartford pull,,, that was the first time we ever ran it pulling,, died on all three trips down the track! Only one good run that day,,,, second time was on our sled, in 2001 at Mentone Indiana, and the 4th time was at Princeton Indiana at the last USAP evdnt Wilder ran at,,, ran the 4500 mod stock, and brought it down to its knees,,,, never killed it, but won the class by 7 feet, out of class of 30 Ms and 88 ollies. the 5th time,,,, Wasnt even pulling it. Was driving it down the road!! From a parade!! Ran all day, ran great, and when I got home, shut it off it wouldnt fire back up. Been in the shed where it sits ever since. Split a sleeve. Maybe the guy who has it on tape, would like to come and pull with us, when I put it all back together. So yeah, Ive stalled it, but when it counted, if it did stall,, it was the new leader. I cant argue with that.
Where you been Phil??? Good to hear from you! Dont care if we dont get along or not,, but I like ya anyways. ChadS [email protected]

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More BS from the drop out

03-01-2008 07:15:27




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 Re: compression in reply to ChadS, 03-01-2008 04:19:29  
Who are you talking to? No one cares about the untrue stories that you make up.

Looks like you screwed another person and then blame it on them. Just like your dad, Denny.


Learn from ChadBS...Stay in school.



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ChadS

03-01-2008 04:04:29




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
Hello Munson. Ya win some, ya lose some, but we played the game. ChadS [email protected]



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MLPANKEY

02-29-2008 08:28:52




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 Re: compression in reply to AO, 02-21-2008 10:01:45  
the head needs bigger valves and some flow work also needs a different cam. you could play with the valve lash and see if it responds . tighten the lash up .002 than where you run it at .if it responds you need more lift and can stand to advance the cam 4 degrees. open the lash .002 up farther and you may need to retard the camshaft for it to work. little tricks i learned from lunati. one tooth on the gear is 6.6 degrees . playing with the valve lash has made 5 more horses on the dyno many times. usually when you increase cubic inches you incresase the demand for air and thats what that engine is in need of more air you will also see the 245 psi go up when you introduce more air to it . more air more fuel more power.

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MLPANKEY

02-29-2008 08:11:31




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 Re: compression in reply to ERS, 02-21-2008 10:01:45  

MLPANKEY said: (quoted from post at 09:07:00 02/29/08) CHAD if it did not have anything but .040 head gasket for a combustion chamber the compression would be 25.1 guessing ill run the numbers later . which i never said go that high. i also womder if it bent any valves .040 thousand piston to valve is tight not to say they want run there . usually need alot of spring to keep up with that close of clearance. also never had any results mixing alcohol with gas they usually seperate . alcohol needs 1.7.1 air ratio gas needs 1.14.1 . see what happens when it seperates motor goes lean
i missed the guess it would have had a static compression ratio of 130.1

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MLPANKEY

02-29-2008 08:07:00




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
CHAD if it did not have anything but .040 head gasket for a combustion chamber the compression would be 25.1 guessing ill run the numbers later . which i never said go that high. i also womder if it bent any valves .040 thousand piston to valve is tight not to say they want run there . usually need alot of spring to keep up with that close of clearance. also never had any results mixing alcohol with gas they usually seperate . alcohol needs 1.7.1 air ratio gas needs 1.14.1 . see what happens when it seperates motor goes lean

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ChadS

02-28-2008 18:55:35




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
The ring lands broke from being the original pistons,,, and they added the stroker crank to em, and guess,,, never knew it had no compression chamber in the head!! from the cyl pressure alone was enough to blow the rings darn near off the pistons,,,,

when it did pop,, never really heard it long enough,, nor got the chance to stress test,,, soon as the pto was turned on the rpms came down a little and it stopped dead in its tracks would slowly turn over,,, thought,,,, whoops!!! But things looked fine in the bores,,, one cyl was way down on pressure,,,, thats when we found the pistons,,, flat top pistons,,, came to the top of the block.... the head and cam is bone stock D-17,, just acts like something is holding it back though,,,,, it lugs out,,, but its lazy in the lower rpms. From how Ive seen it on the track and on a dyno,, youd swear its two different machines it grunts, but it could do better I think,,, runs on whiskey and pump gas for fuel. CHadS [email protected]

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buickanddeere

02-28-2008 09:20:23




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
340 psi compression & blown the piston lands clean off it!! In this situation it looks more like detonation that broke that piston. Too much compression, too much timing advance or too lean a mixture.
When the throttle blades are nearly closed. The cylinder pressure can be in the 100's psi or even less.
When the throttle blades opens up now the cylinders were getting filled fuller and the compression pressure went to 200 or 300+psi.
The air/fuel mixture auto igitied due to pressure increase/heat before the piston reached top dead center = crunch. That engine needed 115 octane fuel and modest timing advance.

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ChadS

02-28-2008 07:17:02




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
MLPankey, What make is the engine you have 350 psi of cyl pressure in??? I have seen "hyd lock" in a D-17 5.5 stroke. A fella had this one done up, brought it over to the shop, got it running, ran a cyl test, was 340 psi,,,, well, it ran good with no load, put it onthe dyno just put a light load on it and it sounded like it dropped a bolt indise the cyl. Took the head off,, blown the piston lands clean off it!! Also noticed the pistons came up to the top of the block at TDC,,,, No block damage, so I dropped in a set of Ford 351 pistons, flat tops, I cant remember how far down in the cyl they were, but the final cyl test was 245,,,, no knockin no pingin, had good power in the higher rpm ranges,, on the dyno, was a little lazy on the low end torque,, better than stock,,, but for what it was,, just seemed like it was slow to come on,,,,, so withthat in mind,, he took it out and ran it for a few seasons,, did well, but its now been sitting for a spell,,, he called me up the other day, it hasnt run in a while, its in a WC chassis,,, the engine is,,, last dyno pull was bout 65 hp with about 2 hours of run in time. I know its stroked enough to have to notch the block, but the stock oil pan fits with a slight ding where the rods pass by,,,,, no pan notches if that means anything,,,,, His son is in school,, and they want to go pulling this summer,,,, firsttime out with it,, the kid won 4th place with it down in princeton a few years ago. ChadS [email protected]

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mlpankey

02-28-2008 11:56:07




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 Re: compression in reply to ChadS, 02-28-2008 07:17:02  
chad at 245 psi thats usually 11.1 and about 1/2inch below the deck if its a true flat top if its a reverse dome it will be higher in the block due to the ccs of the dish. i use to run 11.1 but since running new motor with higher compression ill never look back at 11.1



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mlpankey

02-28-2008 11:45:46




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 Re: compression in reply to ChadS, 02-28-2008 07:17:02  
i have had engine sdo exactly what you say chad . itwas a simple fix if it didnt destroy the pistons . the simple fix was 2 or 3 step colder spark plugs.



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mlpankey

02-28-2008 11:40:25




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 Re: compression in reply to ChadS, 02-28-2008 07:17:02  
somebody didnt know how to build ad17 motor cause thats what mine is and i usually let it pull down to 800rpm before rolling the clutch in. 5.80 stroke diesel rod 2.0 piston pin height. timing and fuel will make one deatanate. but hydrualic lock means it want turn over and rods are bent or broken



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Loco guy

02-26-2008 18:42:37




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
OK, with all of this compression, how do you crank it over??? I have a Farmall H with around 145 pounds compression and it doesn't seem to want to crank even on 12 volts and a new rebuilt 6 volt starter. Also, does anyone know how much total timing advance an H can handle before the pistons end up in the oil pan??



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mlpankey

02-27-2008 11:13:59




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 Re: compression in reply to Loco guy, 02-26-2008 18:42:37  
i use 1 /0 welding cable for battery cables and one battery from car quest with 1100 cranking amps and have no promblem cranking 350 + psi.as for advance every bodies engine is different just have to play with . fuel also factors in on timing some fuels need more spark lead than others.



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Loco guy

02-27-2008 15:52:01




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 Re: compression in reply to mlpankey, 02-27-2008 11:13:59  
Thanks, Was leaning towards the heavier cables and a starter relay mounted on the starter to cut down on cable length as much as possible. 1100 cranking amp battery? I assume that is a 12 volt? 350 psi compression?? Most diesels will run on that!!! Just wondering if there was a rule of thumb for the maximin timing advance. Wasn't sure if you can hear the detonation before the damage was done or not. Poor thing barely idles at factory timing specs.

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mlpankey

02-27-2008 17:52:58




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 Re: compression in reply to Loco guy, 02-27-2008 15:52:01  
yep 12volt battery and yep i have more than 350 just cant read above 350. i need a diesel gauge to check it for an accurate reading. some people believe thaT HIGH COMPRESSION causes hydraulic lock but it is physically not possible to stuff enough fuel and air into a naturally aspirated motor to compress it into a solid. the only engines that run on the verge of hydralic lock are top fuel motors with over 3000cfm of air and more fuel than youre bathroom shower puts out a second.

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mlpankey

02-27-2008 19:40:02




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 Re: compression in reply to mlpankey, 02-27-2008 17:52:58  
bottom line is increased compression ratio increases cylinder pressure at low rpms which increases torque at low rpms . but be learry of cam shafts that asked for higher compression ratios especially in pulling cause there duration and overlapp is for higher rpms suffering low end without comp. to offset it.so high comp and cam for low rpms with narrow torque curves makes a successful pulling engine .at least i think so

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mlpankey

02-25-2008 09:49:07




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
yet another with no clue. comp. has nothing to do with rpm curve . can we say top end boys and girls the bottom end has no choice but to do what the top end tells it to other than break if it cant .



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buickanddeere

02-22-2008 14:47:14




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
Actually. If you mount a map sensor to an intake port. Then measure the identical engine with the exception of 5 to 1 vs. 9 to 1 pistons.
The pressure drop in the intake port. Pressure drops faster and lower in the high compression engine. Not a lot but measurable.



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rich4

02-22-2008 12:21:45




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
Compression ratio and cylinder compression are two different things. Compression ratio CC can be calculated by measuring the volume of the cylinder head Turned upside down and filled with some type of oil and measure that volume, then measure the space at top dead center on the block with pistons installed will give you some more volume. If they are domed pistions it complicates matter. Those numbers are your CC volume . Take your bore and stroke and calculate that volume. Divide the smaller in to the larger will give commpression ratio . If this sounds like too much work then ask the piston supplier what the ratio is. Up to 9 something can work with high tech pump gas. If you go to 10 to one or more then use racing fuel. Anything higher would not be beneficial unless you are running very high rpm's.

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mlpankey

02-22-2008 12:33:58




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 Re: compression in reply to rich4, 02-22-2008 12:21:45  
rich4 you did good but you have to figure in the head gasket bore and thickness.



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rich4

02-22-2008 12:53:15




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 Re: compression in reply to mlpankey, 02-22-2008 12:33:58  
Thanks for catching that



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mlpankey

02-22-2008 08:09:53




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
when i built my engine i figured my compression ratio out. after i built it and broke it in feeling that the rings had time to seat . i put my craftsmen compression tester on a cylinder made 2 pumps and pegged the gauge .it reads to 350 psi. so i dont know how much is to much looking for a diesel gauge to see what it is just to keep a eye on ring tension or valves starting to leak by.



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mlpankey

02-22-2008 08:01:47




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
yeahp compression equal horsepwer and torque.will a stick of dynamite in a 40 acre field create as much devastating power as say it would inclosed in a car?



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supera h

02-21-2008 15:40:29




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
it depends on every individual setup, but usually on a JD, it's probalby around a 220-240 range, and on a M sized 4 cylinder or like sized 6 cyl., around 275 max....and oliver like 6cyl and smaller 4cyl can be around 300. these would be max's, but most of the time your going to be way lower. it's mostly based on piston size and stroke. mayhbe some others can add on this...your better off just going on a compression ratio of like 9:1...what are you wanting to pull?

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RKEENE

02-21-2008 13:48:02




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
Are the gains maximized further by a cam change? Can an improved cam design make better use of a compression increase? Instead of just less combustion volume? A cam change alone can increase compression too, can it not?
Is the flattop piston always the most efficient?



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buickanddeere

02-21-2008 13:05:15




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 Re: compression in reply to too much, 02-21-2008 10:01:45  
If flame travel is impeded due to a huge lump on the top of the piston. Or the sparkplug shrouded. The gains in mechanical efficiency will be less than the losses in combustion efficiency. Increasing compression has diminishing returns. Take an 4 to 1 all fuel and increase her 7 to 1 and the power gains are impressive. Maybe 4 more HP on a base 40HP engine. Now take the same 40HP base engine and increase the compression to 10 to 1. There will be a power increase of maybe just 2 HP more with the increase from 7 to 10 for a total of 46HP.

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truth101

02-21-2008 18:17:40




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 Re: compression in reply to buickanddeere, 02-21-2008 13:05:15  
ur all clueless



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Gary Baker

02-22-2008 02:58:23




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 Re: compression in reply to truth101, 02-21-2008 18:17:40  
Finally someone who knows what he is talking about!



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buickanddeere

02-22-2008 08:26:21




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 Re: compression in reply to Gary Baker, 02-22-2008 02:58:23  
true101 ?



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Yep

02-22-2008 11:16:55




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 Re: compression in reply to buickanddeere, 02-22-2008 08:26:21  
True 101 is right, Supea h is about 100 lbs of compression off on every model he listed...



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Where's Denny Jr

02-22-2008 11:28:06




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 Re: compression in reply to Yep, 02-22-2008 11:16:55  
Have ChadBS tell you his law of physics on higher compression and how it makes a motor "suck harder." I'm still laughing at that one.



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ChadS

02-22-2008 19:20:09




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 Re: compression in reply to Where's Denny Jr, 02-22-2008 11:28:06  
Laugh, and the world laughs with you. AHHH laughter,,,, its a wonderful thing isnt it??? Ill be rolling of the floor when ol "Something Wilder" will still be pulling, while the others are,,,, OH crap!! where are they all gone???? turned into Boat anchors!! To visit the titanic. From what I hear, they are lining them up like ducks in a row. And I thought Magic springs were wild!! WHEW! Aint seen nothing yet! HEY WINSTON!!! PEDAL FASTER!!!!

Now ,, there I got it out. LMAO! But I do what I like, I do what I do. Nothing in the world your gonna do bout it. xcept still say the same ol BS,,,, so full of it your eyes are brown arent they??

Sorry for degrading such a great conversation with my BS,,,, You guys keep on keeping on. ChadS [email protected]

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Phil Munson NY

02-29-2008 19:04:52




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 Re: compression in reply to ChadS, 02-22-2008 19:20:09  
What is the stuff about something wilder? One of my neighbors taped you finising dead last and then getting DQued. He thought you were even more absurd in living color than you are here in black and white. THAT is an accomplishment. best, Yeoman
PS: Maybe you could get one of them there MAGIC MIRACLE MONSTER governor springs that $um jeeneu$ $ell$ on this board. I heared him klame it was new teknolgee.

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mlpankey

02-22-2008 12:25:12




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 Re: compression in reply to Where's Denny Jr, 02-22-2008 11:28:06  
dont know about that .opening up the bore does seam to help the head flow by a few more cfms and it does unshroud the valves that buick and deere was attempting to explain . alot of piston manufactures are making alot of money from pistons with domes so high they leave a valley in the dome for flame to travel across the bore. seams to me if theres nothing there major engine builders wouldnt purchase them.

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Hot Rod A

02-24-2008 14:34:02




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 Re: compression in reply to mlpankey, 02-22-2008 12:25:12  
This is a question that doesn't have a definitive answer. It all depends on what motor you're working on, what class you're aiming to pull it in, what type of tracks and sleds you're primarily pulling with, and what rules are in place that you've got to build within.
If you've got rock hard tracks, a nice even-pull weight transfer sled, speed limits and RPM limitations of stock or near stock with a percentage grace, I would advise you to stay around 9-9.5:1, where as if there are no RPM limits, speed limits are lenient if at all, and/or if the sled uses lowering of the pan to stop you rather than a gradual weight transfer, and you need speed to compete, I'd say go with a taller compression ratio, something from 11:1 to 13:1.

For example, take the small block chevys of the 60s and 70s, namely the 327 and 400sbc. The 327 found in Camaros and Vettes had a nice set of high comp heads and pistons, where as the 400 did not, and thus had noticeably lower compression. The 327 off the assembly line would conservatively generate above and beyond 325HP, the 400 didn't even touch 300HP. Now line the two up at the drag strip, the 327 walks away. Hook a trailer up to the two at the bottom of a hill, the 400 is the clear choice. Granted there are many other factors that also will play a part, including how well the intake and exhaust flow, cam specs and desired powerband, and so on, but assuming all else is the same, compression is the next main factor in determining if you need a high hp screamer, or a high torque lugger. Generally speaking, with all motors as you raise compression ratios, depending on where you start for a compression ratio, both the torque and horsepower curves will raise with increased compression until about 9.5:1, after which the HP curve continues to rise with increased compression, the torque curve will begin to fall off.
Hopefully this can be of use to someone. Granted not all of the information applies directly to each and every motor ever made, but it is a pretty good rule of thumb.

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mlpankey

02-25-2008 14:35:33




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 Re: compression in reply to Hot Rod A, 02-24-2008 14:34:02  
youre doing entirely to much tinking. a 327 had good heads duble hump a 400 had the worse chevy heads money can buy. the cam shaft in the 327 was more effective due to lift and duration being able to supply the smaller cubic inch motor more effectively the 400 with double hump heads and a cam that would act the same as the 327 cam does in it and the toque rpm range and horsepower goes up put the compression where it was with the 327 and youll out run any day of the week. no replacement for displacement

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