I decided to test the compression on the cav today. I really don't know what exact compression ratio I have, mostly because of my domed pistons, but I am happy that all the cylinders were extremely close.
The results....
Cyl 1: 255 psi
Cyl 2: 253 psi
Cyl 3: 255 psi
Cyl 4:
124 psi
Just kidding about cylinder 4. It was also about 255 psi. I will have to have Jesse figure out the exact CR of the engine THANK GOD I wrecked two other pistons so I can take a mold of them and figure my cylinder volume. I knew I fubared them up for a reason!
Im going to go out on a limb and say 12.5:1-12.75:1
A healthy engine should put out between 17-20x the CR. and after doing the math and giving it some error room thats the conclusion i came up with.
I like the how close the #s are.
How did you break it in?
Sorry to mini hijack, but what would 225 per cylinder within 2% across the range equal out to on compression?
I've been wondering ever since I checked mine, except math and I are not close friends by any means.
Good to hear your engine is running well Paul, got a good tune on it yet?
Wrench Monkey wrote:Im going to go out on a limb and say 12.5:1-12.75:1
A healthy engine should put out between 17-20x the CR. and after doing the math and giving it some error room thats the conclusion i came up with.
I like the how close the #s are.
How did you break it in?
Don't forget that my pistons are pretty "domed" tom. Even with it being bored out .002", There isn't as much area in the cylinder as there was stock. Even still that is a crazy ass compression ratio. Good thing I am running 93 octane!
ya did you have a break in schedule so all those parts can get to know each other?
How big are your cams?
My old skewl LZM cams has huge duration... and I only see ~160 per hole.
Built, bottled, ready for 11s. 14.446@93.74mph, 1.848 60' N/A.
225 at 2% is 4.5.
- 2003 CHEVY CAVALIER LS SPORT ECOTEC -
- Current Mods -
-- Vibrant Exhaust & DC Sport Header --
-- Lower Motor Mount & TTR Upper Motor Mount --
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Owen wrote:How big are your cams?
My old skewl LZM cams has huge duration... and I only see ~160 per hole.
I have the JBP stage 2 cams. They have a gigantic duration also. Here are the specs of the cams........
Stage 2 2.4L LD9
Duration @ .050*, Valve Lift INTAKE 260*, 377 EXHAUST 268*, 375
I have scanned the car with my buddies HP tuner. He has it for his GTP, but it still is able to monitor my car, it just can't modify anything. I wasn't running any KR on 93 octane, and I physically can't hear any pinging, so I think I am safe for now. I will be getting it dyno tuned this week, so dyno numbers should be coming soon.
I have 12.5 : 1 pistons and i HAD to run at least 100 no lead, 93 was not workin well for me. I have the comp cams stage 3 cams 450ish lift 220ish duration
Get a hold of me Paul
-Ben
Overall Best times
60' - 1.857 (6/24/07)-(Drag Radials 205-50-15)
330' - 5.552 (6/24/07)-(Drag Radials 205-50-15)
1/8 - 8.690 (7/22/07)-(Conquesrt Radials 195-70-14)
M.P.H. - 81.87 (7/22/07)-(Conquest Radials 195-79-14)
1000' - 11.274 (7/22/07)-(Conquest Radials 195-70-14)
1/4 - 13.442 (7/22/07)-(Conquest Radials 195-70-14)
M.P.H. - 104.08 (7/22/07)-(Conquest Radials 195-70-14)
** ALL MOTOR **
* 181whp @ 7600rpm *
Website: www.benwenzeljr.com
those numbers are false.
a car with 268* of duration at .050 wouldnt run
Built, bottled, ready for 11s. 14.446@93.74mph, 1.848 60' N/A.
Owen wrote:those numbers are false.
a car with 268* of duration at .050 wouldnt run
I just copy and pasted it from JBP's website. Why wouldn't it run?
I don't think that the calculation wrench monkey made is completely correct. There is no way you can accurately figure it out without measuring the dome on the pistons. Wiseco made measurments of an LD9 head when they custom made my pistons. They did the math and claimed the pistons would do 10.5:1 compression. I am going to have to take their word for it, as they have been in the piston making business forever.
Well take 9.5:1 * 20 and you get 190
My last compression test came out at 185 ish.
the calc i got was from the web. btw i saw some 10.5:1 pistons and they dont look like yours but thet are quad pistons
also that doesnt take cams into consideration
Your guess is as good as mine Tom! The bottom line is, it has plenty of compression, which is what ya need for a high hp n/a motor. Hopefully he gets it dyno tuned tommorrow.
Owen wrote:those numbers are false.
a car with 268* of duration at .050 wouldnt run
Im willing to bet those duration numbers are total duration, not at .050. I looked at those specs a while ago and thought the same thing till I figured they weren't at .050. And a car can run with that much duration at .050, just probably nothing this side of a pro stock car
13.934 @ 97.82
ALL MOTOR
well, im saying it's definatly a safe bet to say you've got more CR than stock
your pistons are MASSIVE compared to stock.
when i did my testing on the stock bottom end engine in my car now, the numbers were from 199-205. most stock 2.4's see the same. you've obviously got more.
Your telling me you didnt degree your cam to figure out the true specs, opening, and closing events of your cam? AND its from JBP, and they have a history...and not a good one? Doing small things like degreeing your cam or cams in this case, puts you ahead of the competitors, the competitors that buy expensive parts and expect to win. Engine building doesnt work like that. Do the small things, the detailed things.
cams... i have some big Quad-4 cams siting around.. .450/232 intake and .430/232 ext. stock EPROM dident like them
so, what is its compresion>?
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
bmxludwig wrote:Your guess is as good as mine Tom! The bottom line is, it has plenty of compression, which is what ya need for a high hp n/a motor. Hopefully he gets it dyno tuned tommorrow.
id bet its at 11.5:1 at least. but we will not know until he figures it out. I want to see you spray this bitch
spray comes next spring. just a quick question right now we get about 36-38 psi of oil pressure when were ramming on her and 25-28 when cruising at 2500rmp sound about right? on my pump swap the feed hole i believe is drill to 41/64"
also the air vent controls wont work vents wont blow air and the rad fan wont kick on any ideas check all fuses and switches?
Dyno tune next Wednesday
haha. i had the same problem with the heater. lol. its a ground. thats what i found out. theres one that goes to the bellhousing bolt on the trans right below where YOUR PS pump would go. at least thats where mine is
^^^ that's what i was thinking too but i looked and i have the grounds on the harness bolted to the housing so i look on my black auto and there are two lil black wires that need to be grounded does the manual have the same wires ? couldn't find them if there there
Mine was something like
202-204-164-208
Or something really close to that. Been months since I did a compression test.
I have some blow by issues on 3.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
255psi? your compression is around 11:1. FYI, I have 12:1 with .430" and 224* cams and I have 285psi per hole.
Nothing to get all wet for. 11:1 is not high at all.
Gilles
2.3 Ho
