5.3 H/C/I in a 4th gen, some technical heads questions
12-10-2010, 09:48 AM
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5.3 H/C/I in a 4th gen, some technical heads questions Couple years ago stuffed a 5.3 in my v6 camaro. Car now functions perfectly normal as any other ls1 car. Looks factory, no codes, all is well.
Round one-
Stock internals 5.3
ls1 intake
headers and full exhaust
built trans w/2200 stall
271rwhp/306rwtq
13.86@108
Round two-
Stock bottom end
Stock 862 heads
TR224 cam
ls6 intake
Headers w/full exhaust & e-cutout
built trans w/3600 stall
321rwhp/338rwtq
12.90@112
Round 3- Looking for some more umph, like 400rwhp. Looking at a set of GMPP CNC 243's, 60cc version. The chambers in these are just a pinch smaller than the stock 862's so that will help my measly 9.4CR, but im looking to bring that into ls1 territory, 10.5/1ish.
Can I mill the GMPP CNC 243's any to bump up the cr any more? Can I do this with these heads? Will I experience PTV issue with the TR224 cam thats in the car?
What are the odds of actually getting 400 out of it?
Round one-
Stock internals 5.3
ls1 intake
headers and full exhaust
built trans w/2200 stall
271rwhp/306rwtq
13.86@108
Round two-
Stock bottom end
Stock 862 heads
TR224 cam
ls6 intake
Headers w/full exhaust & e-cutout
built trans w/3600 stall
321rwhp/338rwtq
12.90@112
Round 3- Looking for some more umph, like 400rwhp. Looking at a set of GMPP CNC 243's, 60cc version. The chambers in these are just a pinch smaller than the stock 862's so that will help my measly 9.4CR, but im looking to bring that into ls1 territory, 10.5/1ish.
Can I mill the GMPP CNC 243's any to bump up the cr any more? Can I do this with these heads? Will I experience PTV issue with the TR224 cam thats in the car?
What are the odds of actually getting 400 out of it?
12-10-2010, 03:59 PM
#3
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I had the opportunity to get a set for 500. Thought itd be a good deal. But it looks like there sold.
Is it worth it to port and mill my 862s? Or only if I had the 2in intake valves put in?
Is it worth it to port and mill my 862s? Or only if I had the 2in intake valves put in?
12-10-2010, 09:54 PM
#4
To get 400 your going to need to Go with a set of 205's in an aftermarket casting, run 4.8 flat top pistons to get the compression up (if you have an older 5.3 that didnt come with them). Yes they will fit.
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.
Your going to need something better than an off the shelf cam. So, I would talk to some of the cam guru's and have one spec'd with your goals in mind. You would need the 4.8 pistons to keep the DCR up in a respectable number so it will swallow a decent sized cam to get your numbers. 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.
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.
Your going to need something better than an off the shelf cam. So, I would talk to some of the cam guru's and have one spec'd with your goals in mind. You would need the 4.8 pistons to keep the DCR up in a respectable number so it will swallow a decent sized cam to get your numbers. 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.
12-10-2010, 10:01 PM
#5
Couple years ago stuffed a 5.3 in my v6 camaro. Car now functions perfectly normal as any other ls1 car. Looks factory, no codes, all is well.
Round one-
Stock internals 5.3
ls1 intake
headers and full exhaust
built trans w/2200 stall
271rwhp/306rwtq
13.86@108
Round two-
Stock bottom end
Stock 862 heads
TR224 cam
ls6 intake
Headers w/full exhaust & e-cutout
built trans w/3600 stall
321rwhp/338rwtq
12.90@112
Round 3- Looking for some more umph, like 400rwhp. Looking at a set of GMPP CNC 243's, 60cc version. The chambers in these are just a pinch smaller than the stock 862's so that will help my measly 9.4CR, but im looking to bring that into ls1 territory, 10.5/1ish.
Can I mill the GMPP CNC 243's any to bump up the cr any more? Can I do this with these heads? Will I experience PTV issue with the TR224 cam thats in the car?
What are the odds of actually getting 400 out of it?
Round one-
Stock internals 5.3
ls1 intake
headers and full exhaust
built trans w/2200 stall
271rwhp/306rwtq
13.86@108
Round two-
Stock bottom end
Stock 862 heads
TR224 cam
ls6 intake
Headers w/full exhaust & e-cutout
built trans w/3600 stall
321rwhp/338rwtq
12.90@112
Round 3- Looking for some more umph, like 400rwhp. Looking at a set of GMPP CNC 243's, 60cc version. The chambers in these are just a pinch smaller than the stock 862's so that will help my measly 9.4CR, but im looking to bring that into ls1 territory, 10.5/1ish.
Can I mill the GMPP CNC 243's any to bump up the cr any more? Can I do this with these heads? Will I experience PTV issue with the TR224 cam thats in the car?
What are the odds of actually getting 400 out of it?
If you step up to aftermarket castings (which IDK that i necessarily would do on the 5.3) then look @ TFS. Here is my issue with the aftermarket casting you are gonna pay alotta $ for something you can't really take maximum advantage of...now on the flip side, if you buy a high dollar head now, you could run it, then swap it over to a built shortblock later on...
Just all depends on your budget. I would say call Phil @ AI, tell him your goals, and his head in the link above, or the 5.3 head he has in development might fit your bill nicely...and you may make more power than you expected!
12-11-2010, 08:39 AM
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I was trying to avoid pulling the motor for a 3rd year in a row.
If it's going to take new pistons to get me close to the 400 mark, then I may just hit it with a 100 shot and call it a day. Cash is a little tight and so is time.
Would it be worth haveing mycurrent heads re worked vs the gmpp ones? Any idea what I'd be looking at power wise?
Aftermarket castings are out of the question due to cost.
If it's going to take new pistons to get me close to the 400 mark, then I may just hit it with a 100 shot and call it a day. Cash is a little tight and so is time.
Would it be worth haveing mycurrent heads re worked vs the gmpp ones? Any idea what I'd be looking at power wise?
Aftermarket castings are out of the question due to cost.
