Compression

[hammertime]

Hey guys, thinking about bumping my compression up this winter, not 100% trying to figure out if the hp/et gain is worth changing up my combo.
Now it has 12.5 going to 14.5-15, 582 BBC made 970hp

What hp and on track et you think i'll gain by 2 points ?
thanks in advance !

[jmarksdragster]

May help a little with consistency as well as HP. I'm going between 15 and 15.5 on my 460.

[zipper06]

Alcohol love's compression, you can't get too much. Look at it this way top alcohol cars are running 12 to 1 and spinning the blowers at 40% OD pushing 40lbs boost. In the mid 80's i was running a 1471 blown alcohol 540" B/blk with 13 to 1 and spinnig the blower at 40%. I've got 11 to 1 in my s/blk with a 1471 and spinning it 1 to 1. I have 13.7 on the 377" and 14.5 on my 434"

JMO

Zip.

[itsabird]

pickup in hp and et for sure.

[bjuice]

i know you have heard enough about PAR racing engines lately...but here we go again.... all his raw motor engines is nothing less then 15 to 1..
My 15 to 1 565ci with smaller heads (valves) than yours is making 30 hp more than your 582ci

you put your 582ci 15 to 1 and i personally think you will put that bad boy close to the 1100 hp mark if the rest of your combo is right for the job. :wink:

I will say 80 to 100 hp gain and 2 to 3 tenths quicker...your 4.70's and 136 mph range now..right ?

IMO

[hammertime]

pickup in hp and et for sure.

How much is the main questions I guess, we talking 2-3 hundreths ?

Its very consistent as is, just thought if I was leaving a good tenth on the table ?

I've did this move before 10:1 to 15.5:1 on a alky motor, seen very little gain which I thought was odd.

[hammertime]

i know you have heard enough about PAR racing engines lately...but here we go again.... all his raw motor engines is nothing less then 15 to 1..
My 15 to 1 565ci with smaller heads (valves) than yours is making 30 hp more than your 582ci

you put your 582ci 15 to 1 and i personally think you will put that bad boy close to the 1100 hp mark if the rest of your combo is right for the job. :wink:

I will say 80 to 100 hp gain and 2 to 3 tenths quicker...your 4.70's and 136 mph range now..right ?

IMO


Most high end builders are 15.5-16:1 making 1080-1100. I'd go out on a limb and say mine goes 1040-50 maybe higher on any dyno but Nyes. That dyno has to be bar none the most honest dyno I've seen.

80-100hp gain that'd be worth the jump for sure. Right now 4.7's@146 instead of 136

[michael1]

I wanted 12.5 and my engine builder told me to put at least 15-1 he said it would be a major difference but I'm building a 632 18* motor with two dominators. Ask Pat at Nyes you know he won't stear you wrong,he is very honest.

[bjuice]

Hey compression is HP anyway you spread it..weather its achieved thru a turbo,blower,NOS or just built into the motor Naturally aspirated. there are no 11-12 to 1 engines setting any records out here...unless its static compression with a 30/35lb huffer sitting on top...lol :D

[Tod74]

BJUICE you gona run that new one on alcohol or gas?

[itsabird]

bjuice hit the nail on the head, i have heard some guy,s say you can have too much, and under some conditions this may be true, but i don,t see 14-15-1 being close to those conditions. and would be the min.. i would want for a race motor. jmo

[bjuice]

BJUICE you gona run that new one on alcohol or gas?

VP c-16 gas

[desoto30]

I was once told something that appears obviously true."there is only one way to make more power,increase cylinder pressure how you do this doesnt matter"obviously the fuel must be able to take it,methanol can & who knows what the upper CR limit is.

[R71chevynova]

I'm not saying don't raise your compression, but don't expect a 100+ HP gain, by just raising the compression from 12.5-14.5, with no other changes. HP don't come that easy.

My engine program shows a 16 HP gain on a methanol 582" engine making 970 HP, by raising the compression from 12.5/1, to 14.5/1, and it assumes the dome size needed to raise the compression, didn't start hindering flame travel, or causing some other combustion issues.

I think 16HP is more realistic, than 100+.

Randy

[maxpower671]

there are tables and formulas for calculating how much compression increases power. diminishing returns...

if cylinder pressure is greater before ignition, chances are good it will be greater after ignition..

not sure what maximum compression with methanol is, as long as rich, it will be accomodating..

[hammertime]

Looks like come spring we will get some real #'s on what the compression change is. Motor is going to need new pistons (block was a bit out of round) so I am just making the move to bump compression upto 14.5-15:1

[itsabird]

there ya go hammer, and hang on tight. :lol:

[hammertime]

I'll hope for a bunch of hp but wont need it, the motor is pretty good as is but everyone always wants more power right :lol: :wink:

[itsabird]

yep, too much is not enough. :lol:

[Pwmax]

You won;t pick up 100, but I would say from expierience, 20-25, maybe 30hp. Which, if you need pistons anyhow, why not. If it was going from 10:1 15:1, you could expect possibly 100hp, but your at the point of diminishing returns. Q-16, will add another 35-40hp over C-16, once tuned properly. Its expensive, and stinks, but definately makes more power.

Frank

[olds48]

I don't know this for a fact,but have been "told" on more than one occassion that a point of compression is worth roughly 3-5% :? ?????

[hammertime]

Making another change also was going to just recondition rods but decided to buy new instead while doing so I am changing from 6.385 to 6.535 for a better rod angle. Machine shop thinks this will take advantage of the heads I have. what do you guys think about this swap ? :shock:

[zipper06]

The longer rod in most cases will help because it reduces side load on the piston and permotes better sealing of the rings due to piston rock. Ofcourse the higher up you get in the piston with the rod the less rock anyway. I think there's also a theory that the piston travels faster on the down stroke with a longer rod, but i don't know how that works. If you look at the Nascar guys, they are running real short pistons, 3.2 stroke and 6.2 lg rods with the sm/blk chevies and i don't think they base that on theory, but instead what works best, produces power, and what runs longest without losing power from piston and ring wear.
How much HP gain? i don't know :wink: only the the car will know.

JMO

Zip.

[hammertime]

Zip thanks for the reply, I was thinking the less piston rock also main reason I actually decided to go this way, plus if there is a chance ya gain a few horse might as well try it for the same money :D

I am trying a new rod this go around, always iffy on doing this, I am a big eagle fan with the L-19's, was going to go callies compstars or K1's decided to go K1's with arp 2000 bolts, motor shop has used them a lot in some high HP stuff with nitrous and says they are a great rod, better then eagle and equal to callies compstars for sure. I also elected to go with Diamond Pistons 14:1 compression.

[hammertime]

Hope to find out the difference here in the next 2-3 weeks, got it started up today for first time. Good to hear a race car again :D

[BEAST477]

Yeah hammertime nothing like the sound of big cubes and the smell of race fuel. I'll bet you were glad to hear it fire again. :D

[dparker]

Hope to find out the difference here in the next 2-3 weeks, got it started up today for first time. Good to hear a race car again :D

David, are you running racing fuel or alcohol on this engine.

[hammertime]

Yeah hammertime nothing like the sound of big cubes and the smell of race fuel. I'll bet you were glad to hear it fire again. :D

More then glad to hear the sound of a race car besides on tv and the www lol

[hammertime]

Hope to find out the difference here in the next 2-3 weeks, got it started up today for first time. Good to hear a race car again :D

David, are you running racing fuel or alcohol on this engine.

This will be a alky motor with a terminator on it .

[ashbros]

I had a 615 BBC on alky that was at 13.5/1 made 974 hp kicked it up to 15/1 made 1084 hp didn't change anything else on motor

[hammertime]

well guys todays the day, we will know what kinda difference compression and a 6.535 rod makes over the lower compression and 6.385 rod. Leaving in a few minutes for the couple hr drive to Nyes for dyno day :D

[Tod74]

WHAT is tthe cost on average for dyno time and do they usually help you find the tune up or are they just renting you the dyno?

[BEAST477]

Good luck today hammertime, give us the results last yrs #'s to this yrs #'s. I'm going with my original setup today at the track. Going back tomorrow to test. Probably see you there.

[tcarda]

WHAT is tthe cost on average for dyno time and do they usually help you find the tune up or are they just renting you the dyno?

I have been to two different dyno places and both used the same Superflow dyno. One placed charged $250 for 4 hours and the other one was around $300 for 4 hours. Both are good operators and knowledgeble.

[Tod74]

WHAT is tthe cost on average for dyno time and do they usually help you find the tune up or are they just renting you the dyno?

I have been to two different dyno places and both used the same Superflow dyno. One placed charged $250 for 4 hours and the other one was around $300 for 4 hours. Both are good operators and knowledgeble.

wow that isn't too bad...I figured much more $$$

[hammertime]

well guys I am only in for a few minutes but I'll just say it now has the highest conv headed 582 #'s on nyes dyno :lol:

its up 50hp and 35 tq from last year :D

[hammertime]

Before

http://i203.photobucket.com/albums/aa306/Dragster387b/100_1139.jpg

After
http://i203.photobucket.com/albums/aa306/Dragster387b/100_1144.jpg

[tcarda]

NICE NUMBERS HAMMETIME!!! :D :D

[I972Nova]

Bonafide 1000+ HP.... Very Nice!

[BEAST477]

You gotta be pleased with those numbers. 8) See ya at the track tomorrow.

[zipper06]

David,
looking at the difference in torque values between the last motor and this motor, you might benifit from a little tighter converter, maybe 5500 to 5800. I think i read somewhere you were running a 6200 stall.
Nice numbers though for sure.

JMO

Zip.

[hammertime]

You gotta be pleased with those numbers. 8) See ya at the track tomorrow.

see ya there :)

[hammertime]

David,
looking at the difference in torque values between the last motor and this motor, you might benifit from a little tighter converter, maybe 5500 to 5800. I think i read somewhere you were running a 6200 stall.
Nice numbers though for sure.

JMO

Zip.

Hey Zip, thanks was a 6750-6800 stall now a 6500, I run my stuff on the loose side so its not very aggressive down low.

[zipper06]

David,
looking at the difference in torque values between the last motor and this motor, you might benifit from a little tighter converter, maybe 5500 to 5800. I think i read somewhere you were running a 6200 stall.
Nice numbers though for sure.

JMO

Zip.

Hey Zip, thanks was a 6750-6800 stall now a 6500, I run my stuff on the loose side so its not very aggressive down low.

I guess you're right i'm just used to these heavy weights.The lightest thing i've sat in, in yrs. and that was 2750 lbs and those have all been sm/blks with not a ton of torque. The last time i put a 7" 6200 converter in my 3100lb car it slowed down 10mph and 1/2 second, so i scrapped the idea of ever doing that again.

Zip.

[hammertime]

David,
looking at the difference in torque values between the last motor and this motor, you might benifit from a little tighter converter, maybe 5500 to 5800. I think i read somewhere you were running a 6200 stall.
Nice numbers though for sure.

JMO

Zip.

Hey Zip, thanks was a 6750-6800 stall now a 6500, I run my stuff on the loose side so its not very aggressive down low.

I guess you're right i'm just used to these heavy weights.The lightest thing i've sat in, in yrs. and that was 2750 lbs and those have all been sm/blks with not a ton of torque. The last time i put a 7" 6200 converter in my 3100lb car it slowed down 10mph and 1/2 second, so i scrapped the idea of ever doing that again.

Zip.

This one is 1981 with me in it a few weeks ago, I've tried a tighter converter in it last year 6100-6200 stall and it didnt like it much.
I'll have some track results today I hope :D

[hammertime]

Update you guys on the long rod and compression

Dyno Results very good ... track results its worth slim to none et wise but have seen mph difference.
I was told the long rod would look good on the dyno, so far its been 7.52@179 mph

I've swapped headers and 4 different converters, msd digital 7 along with coil, back tires, shift points, launch points .. all has changed nothing.

[zipper06]

I think the long rod motor creates a little more torgue, but would not be as evident on a light car such as a dragster, SO a tighter converter just might show improvment on the ET. I know you like to run a loose converter to keep the violence down in the first 100 ft.. Heck i'd put a 5500/5800 in it to see if it changed, the compression is not going to help on the top end unless you're running 8500 rpm.

JMO

Zip.

[hammertime]

Thanks for the reply zip .. tight converter is slow and more often then not in the dragster it will be. I tried 5400/5800/6200/6700 stalls already, 6200 fastest 6700 next fastest. 5400 by far the slowest.

[zipper06]

Well guess you got me on that one, since you've been there. I'm more used to the high winding sm/blks and lower geared rearends.

Zip.

[michael1]

Hammertime, you seem to be on top of things with the horsepower and compression deal, so I would like to ask what you think. I ended up with 13.3-1 instead of 15-1 compression. I wanted to know about how much power difference do you think that is. It's a 632 with Dart Big Chiefs and two dominators. The cam is 284in-304ex @ .50 on a 114 LC. The pistons are shipping out on Monday so I can still change them if need be. Thanks

[hammertime]

This is my second motor going to bigger compression first one 548 10:1 went to 15:1 seen slim to no difference. I am actually up on hp/tq with this one on the dyno but think its slower on the track.

Better flame travel with less compression seems to work good. I think you'll be fine

[michael1]

Thanks David, I did order nitrous pistons just in case I need a little more power. How much hp do you think it will make on motor? How does this compare to your combo? Thanks

[hammertime]

That combo should dominate mine, 18 degree heads and 50ci more. Depending on which big chief heads they are i'd think it'd make around 1125hp on a honest dyno