how come people stick to a 224 in a 5.3?
08-19-2009, 09:01 PM
#21
then that would help a ton, if you wanna go real big duration even higher is fine, have you read about STATIC compression and DYNAMIC compression? DYNAMIC brings the cam into play in the compression ratio, the question you are asking is about STATIC compression and really means nothing once the cam comes into play, its really all about DCR.
Basically speaking.... the bigger the cam the lower the DCR.. Do some reading on it and you will understand much better.
I do not know how much you need to mill the heads or can before you get into piston to valve clearance, besides you would have to know what cam you are running and what head gasket thickness before that could be calculated anyway. Sorry can only answer part of your question.
Also.. the really big cams are for big end pull, do you want all high end or do you want low end grunt? Thats another wonderful thing about the 224, low end.
If you wanna budget hard running 5.3, mill the heads and do a Z06 cam, it wont be doing wheelies but it will be snappy and fun.
Basically speaking.... the bigger the cam the lower the DCR.. Do some reading on it and you will understand much better.
I do not know how much you need to mill the heads or can before you get into piston to valve clearance, besides you would have to know what cam you are running and what head gasket thickness before that could be calculated anyway. Sorry can only answer part of your question.
Also.. the really big cams are for big end pull, do you want all high end or do you want low end grunt? Thats another wonderful thing about the 224, low end.
If you wanna budget hard running 5.3, mill the heads and do a Z06 cam, it wont be doing wheelies but it will be snappy and fun.
i was only gonna go into the 230's somewhere around 231/234 (torquer v3), some milled ls6 heads and a single plane setup with a 4150 TB
08-19-2009, 09:24 PM
#22
Most of what is said above is general theory, dont go slap together a motor based on my comments lol. But it should be a good place to start, tell you what I have always got great answers on stuff like this from texas speed, you might give them a shout and see if they have experience with this. Then also check with predator z, he really knows his cams.
08-19-2009, 11:14 PM
#23
In order to bring the 5.3 to 11.5:1 compression you would need to run an 0.040 gasket and mill the heads to 50cc's. To get a 5.3 head to 50cc's you would need to mill over .080" and an LS6 head over .100" and neither of these will come highly recommended. This illustrates another problem with the small bore; it displaces less air, which means it's not as easy to get the compression up without changing to a flat top or dome piston.
If you use the DCR as a reference as to what cam is like an MS4 in a 5.3 the answer is a 220/220 cam. An MS4 in a stock LS1 puts the DCR at 7.57 and a 220/220-111+2 in a stock 5.3 puts the DCR at 7.59. This is why people don't exceed the 224 cam in a 5.3.
If you use the DCR as a reference as to what cam is like an MS4 in a 5.3 the answer is a 220/220 cam. An MS4 in a stock LS1 puts the DCR at 7.57 and a 220/220-111+2 in a stock 5.3 puts the DCR at 7.59. This is why people don't exceed the 224 cam in a 5.3.
08-20-2009, 11:48 AM
#25
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then that would help a ton, if you wanna go real big duration even higher is fine, have you read about STATIC compression and DYNAMIC compression? DYNAMIC brings the cam into play in the compression ratio, the question you are asking is about STATIC compression and really means nothing once the cam comes into play, its really all about DCR.
Basically speaking.... the bigger the cam the lower the DCR.. Do some reading on it and you will understand much better.
I do not know how much you need to mill the heads or can before you get into piston to valve clearance, besides you would have to know what cam you are running and what head gasket thickness before that could be calculated anyway. Sorry can only answer part of your question.
Also.. the really big cams are for big end pull, do you want all high end or do you want low end grunt? Thats another wonderful thing about the 224, low end.
If you wanna budget hard running 5.3, mill the heads and do a Z06 cam, it wont be doing wheelies but it will be snappy and fun.
Basically speaking.... the bigger the cam the lower the DCR.. Do some reading on it and you will understand much better.
I do not know how much you need to mill the heads or can before you get into piston to valve clearance, besides you would have to know what cam you are running and what head gasket thickness before that could be calculated anyway. Sorry can only answer part of your question.
Also.. the really big cams are for big end pull, do you want all high end or do you want low end grunt? Thats another wonderful thing about the 224, low end.
If you wanna budget hard running 5.3, mill the heads and do a Z06 cam, it wont be doing wheelies but it will be snappy and fun.
08-20-2009, 05:55 PM
#28
In order to bring the 5.3 to 11.5:1 compression you would need to run an 0.040 gasket and mill the heads to 50cc's. To get a 5.3 head to 50cc's you would need to mill over .080" and an LS6 head over .100" and neither of these will come highly recommended. This illustrates another problem with the small bore; it displaces less air, which means it's not as easy to get the compression up without changing to a flat top or dome piston.
If you use the DCR as a reference as to what cam is like an MS4 in a 5.3 the answer is a 220/220 cam. An MS4 in a stock LS1 puts the DCR at 7.57 and a 220/220-111+2 in a stock 5.3 puts the DCR at 7.59. This is why people don't exceed the 224 cam in a 5.3.
If you use the DCR as a reference as to what cam is like an MS4 in a 5.3 the answer is a 220/220 cam. An MS4 in a stock LS1 puts the DCR at 7.57 and a 220/220-111+2 in a stock 5.3 puts the DCR at 7.59. This is why people don't exceed the 224 cam in a 5.3.
holy ****, thats far worse than I would have guessed... Sounds like the best idea would be to go ahead and bore it out for more cubes and put in higher compression pistons.
5.3L Jimmy, do the 5.3 pistons have a large dish/-cc? ( im gonna assume yes by what you posted, just didnt know to what degree )
08-20-2009, 08:46 PM
#30
08-20-2009, 08:58 PM
#32
I never do it. New pistons get new bores, honed with torqueplates bolted on. I'm picky about my builds, they work 100% of the time and I don't end up here posting WHYS MY ENGINE BURNING OILZ!?!1!
08-20-2009, 09:44 PM
#34
Next cheapest route could be to bore the iron 5.3 block to accept 3.898" bore 5.7 pistons. You should be able to find 5.7 takeout pistons in the for sale section from someone going to a forged motor. Better yet, get the whole rotating assy.
08-21-2009, 08:45 AM
#36
holy ****, thats far worse than I would have guessed... Sounds like the best idea would be to go ahead and bore it out for more cubes and put in higher compression pistons.
5.3L Jimmy, do the 5.3 pistons have a large dish/-cc? ( im gonna assume yes by what you posted, just didnt know to what degree )
5.3L Jimmy, do the 5.3 pistons have a large dish/-cc? ( im gonna assume yes by what you posted, just didnt know to what degree )
Originally Posted by nastychevelle
what about using 4.8L flat top pistons?
08-21-2009, 09:01 AM
#37
The compression height will be different on the 4.8l pistons though. Do not know the specs off hand but it might or might not work how you want it. The 4.8l used a longer rod because of the 3.27" stroke, but that does not automatically mean the compression height is close to the same.
08-21-2009, 10:05 AM
#38
4.8L stroke = 3.268" w/ rod length of 6.276
5.3L stroke = 3.622" w/ rod length of 6.098
6.276 - 6.098 = 0.178
0.178 x 2 = 0.356
3.622 - .356 = 3.266
3.268 - 3.266 = .002
So the 4.8 liter piston may have a compression height that is .002 different than the 5.3, but I'm sure that it is the same and just comes out the hole .002" more. I'm sure in the interest of keeping production cost down that GM did not cast a different piston to move the compression height by 2 thousandths, but either way you're not talking about much difference.
5.3L stroke = 3.622" w/ rod length of 6.098
6.276 - 6.098 = 0.178
0.178 x 2 = 0.356
3.622 - .356 = 3.266
3.268 - 3.266 = .002
So the 4.8 liter piston may have a compression height that is .002 different than the 5.3, but I'm sure that it is the same and just comes out the hole .002" more. I'm sure in the interest of keeping production cost down that GM did not cast a different piston to move the compression height by 2 thousandths, but either way you're not talking about much difference.
08-21-2009, 10:19 AM
#39
The earlier 5.3's all have a 7cc dished piston. The newer gen 4 5.3's, which come with the 243/799 heads, have flat tops.
If willing to go through the trouble of doing it right this is a very good option. It will allow static compression to be bumped to 11.3:1 with a 58cc head and 0.040" thick gasket. DCR will then be optimal with a cam in the 228-230 range.
If willing to go through the trouble of doing it right this is a very good option. It will allow static compression to be bumped to 11.3:1 with a 58cc head and 0.040" thick gasket. DCR will then be optimal with a cam in the 228-230 range.