New to V8's and looking for opinions
02-20-2019, 10:47 AM
#1
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New to V8's and looking for opinions Hello, so I am new to the V8 world entirely, as I am an import guy, but I have a 93 Mazda RX7 that is getting bastardized (lol) with an iron 5.3 that I got for free. So my plan is as follows. Rebuild the engine (it is currently in the machine shop as we speak) getting bored, decked, etc. So I would really like to enjoy in NA form, but build for boost later (a year or 2 as I have a wedding to pay for next year). So here is my plan and I guess I am just looking to see if this combo will work out for NA and boost later.
241 Heads
5.3 Block
LS1 Intake and throttle body
K1 Rods
Diamond Pistons (not sure on exact specs yet)
LS6 Cam
LS6 Beehives
Now I know for NA, that combo probably isn't going to be the best, but from what I have researched so far, LS6 cams seem to respond well to boost and it would still make a decent street car combo. I plan on using a Tremec T56 with this setup in NA and boost with a twin disc. I have a set of 862 heads, but I don't think its worth it to have them rebuilt if I plan on keeping the car NA for a year or so. Any input is appreciated. Thanks!
241 Heads
5.3 Block
LS1 Intake and throttle body
K1 Rods
Diamond Pistons (not sure on exact specs yet)
LS6 Cam
LS6 Beehives
Now I know for NA, that combo probably isn't going to be the best, but from what I have researched so far, LS6 cams seem to respond well to boost and it would still make a decent street car combo. I plan on using a Tremec T56 with this setup in NA and boost with a twin disc. I have a set of 862 heads, but I don't think its worth it to have them rebuilt if I plan on keeping the car NA for a year or so. Any input is appreciated. Thanks!
02-20-2019, 11:12 AM
#2
TECH Senior Member
If it's the late LS6 cam, it and 5.3's don't get along well. You will lose a lot of low and midrange power. The factory LS6 cam is run retarded by about 4 degrees, killing low end power, especially on a smaller engine like the 5.3.
02-20-2019, 11:48 AM
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Ok, then I am open to suggestions? That is good info, so thanks! Is the early model LS6 cam better for what I need? Or is there an aftermarket cam that would give me decent power NA and still be good for boost? I know you generally can't have the best of both worlds so I am just curious. The reason I landed on the LS6 cam was I was reading on Super Chevy, a budget 5.3 build, that ran a LS6 cam and made good power. I guess worse case, I just do a cam swap later, which isn't a big deal, but I just like to buy once. This might not be the case here.
Last edited by FD3SEvo8; 02-20-2019 at 11:58 AM.
02-20-2019, 11:57 AM
#4
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The early LS6 cam is the same grind as the LS2 cam, and is a far better grind for the 5.3. But there are even far better aftermarket cams for which the LS6 springs will work well. Just don't get anything with more than .550 lift. Check with Texas Speed and Performance, Cam Motion, or now even Summit, as they have some new cams that seem to be working quite well.
02-20-2019, 02:00 PM
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The early LS6 cam is the same grind as the LS2 cam, and is a far better grind for the 5.3. But there are even far better aftermarket cams for which the LS6 springs will work well. Just don't get anything with more than .550 lift. Check with Texas Speed and Performance, Cam Motion, or now even Summit, as they have some new cams that seem to be working quite well.
02-20-2019, 04:22 PM
#6
The LS6 cam is good for boost. You're building a 2500 lb car, low end isn't really a problem, and the LS6 cam will retain more low end than most after market cams will that are car cams.
The 241 heads will do well to keep compression down a hair for your boost plans, but there are many better heads
The LS1 intake blows all the ***, get an LS6 intake at the minimum
The 241 heads will do well to keep compression down a hair for your boost plans, but there are many better heads
The LS1 intake blows all the ***, get an LS6 intake at the minimum
02-20-2019, 06:01 PM
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The LS6 cam is good for boost. You're building a 2500 lb car, low end isn't really a problem, and the LS6 cam will retain more low end than most after market cams will that are car cams.
The 241 heads will do well to keep compression down a hair for your boost plans, but there are many better heads
The LS1 intake blows all the ***, get an LS6 intake at the minimum
The 241 heads will do well to keep compression down a hair for your boost plans, but there are many better heads
The LS1 intake blows all the ***, get an LS6 intake at the minimum
Edit: I guess the good thing is I am not looking to make massive power in NA form. Just get the car running and driveable so I can enjoy it while I piece together a turbo kit.
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02-20-2019, 07:02 PM
#8
TECH Senior Member
If you're going to use stock heads, get 243/799's instead of 241's. They flow a lot better. They came on every Gen IV ('07-up) 4.8/5.3/6.0 truck engine with cathedral heads, so are easy to find.
02-20-2019, 07:09 PM
#9
Part of the biggest issue with the 241's is the combustion chamber is 66.67 cc, on a dish piston 5.3 that's gonna leave you with 8.9:1 compression and you're gonna have one hell of a turd.
Even with 243's you'll only have 9.1:1
With the smallest chamber 61.5 cc truck heads (706 and 862) you only have 9.5:1
If you have flat tops the compression goes up a little and the picture starts looking better.
Best bet is to to shave the 862's a bit, increase compression, run the cheap .045 headgasket (cheap as in 1/3rd the cost of cometics) that WS6store sells and then do your cam and enjoy for a while. Later when you go boost do some 243's and a regular gasket, and maybe mill the 243's a bit to get closer to 9.5 on boost.
Even with 243's you'll only have 9.1:1
With the smallest chamber 61.5 cc truck heads (706 and 862) you only have 9.5:1
If you have flat tops the compression goes up a little and the picture starts looking better.
Best bet is to to shave the 862's a bit, increase compression, run the cheap .045 headgasket (cheap as in 1/3rd the cost of cometics) that WS6store sells and then do your cam and enjoy for a while. Later when you go boost do some 243's and a regular gasket, and maybe mill the 243's a bit to get closer to 9.5 on boost.
02-20-2019, 08:29 PM
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Part of the biggest issue with the 241's is the combustion chamber is 66.67 cc, on a dish piston 5.3 that's gonna leave you with 8.9:1 compression and you're gonna have one hell of a turd.
Even with 243's you'll only have 9.1:1
With the smallest chamber 61.5 cc truck heads (706 and 862) you only have 9.5:1
If you have flat tops the compression goes up a little and the picture starts looking better.
Best bet is to to shave the 862's a bit, increase compression, run the cheap .045 headgasket (cheap as in 1/3rd the cost of cometics) that WS6store sells and then do your cam and enjoy for a while. Later when you go boost do some 243's and a regular gasket, and maybe mill the 243's a bit to get closer to 9.5 on boost.
Even with 243's you'll only have 9.1:1
With the smallest chamber 61.5 cc truck heads (706 and 862) you only have 9.5:1
If you have flat tops the compression goes up a little and the picture starts looking better.
Best bet is to to shave the 862's a bit, increase compression, run the cheap .045 headgasket (cheap as in 1/3rd the cost of cometics) that WS6store sells and then do your cam and enjoy for a while. Later when you go boost do some 243's and a regular gasket, and maybe mill the 243's a bit to get closer to 9.5 on boost.
02-20-2019, 09:35 PM
#12
Well I am not using stock slugs. I plan on a forged rod and piston so I am open to dish or a flat top. I am not new to higher compression and boost, so if a flat top is the way to go to help in both worlds, so be it. I have a boosted Honda that is 10.5:1 tuned on 17lbs. The only reason we didn't go to 25 is I ran out of fuel. Anyway, so if I get a forged flat top slung to raise compression, then I am ok with that. I am not scared of a higher compression for an NA into a boost project. I will be using a Tremec t56 6 speed manual to answer the next question.
So many people are afraid of compression and boost. I had a turbo GSR with Wiseco's, I kept it stock compression too. Did the same when it was on nitrous.
If you do flat tops or close to flat, you can use the heads to get your compression where you want. You can run some 58 cc now and some 65 cc later
02-20-2019, 09:37 PM
#13
If you run flat tops with those 862 milled to 58 cc and run the .045 gasket you'll be at 10.9:1 and you can later grab some stock 243's and be at 10.0:1, or some 243's with a stock gasket and be at 9.8
That's if they come out of the hole .005, and that's on the stock 3.78 5.3 bore
Or just do flat tops and 243's now and boost it whenever you're ready.
That's if they come out of the hole .005, and that's on the stock 3.78 5.3 bore
Or just do flat tops and 243's now and boost it whenever you're ready.
02-21-2019, 07:57 AM
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If you run flat tops with those 862 milled to 58 cc and run the .045 gasket you'll be at 10.9:1 and you can later grab some stock 243's and be at 10.0:1, or some 243's with a stock gasket and be at 9.8
That's if they come out of the hole .005, and that's on the stock 3.78 5.3 bore
Or just do flat tops and 243's now and boost it whenever you're ready.
That's if they come out of the hole .005, and that's on the stock 3.78 5.3 bore
Or just do flat tops and 243's now and boost it whenever you're ready.
Anyways thanks for all the advice. I suppose I'll just use my 862 and have them milled (they need it anyway) and then swap out later. It is a stock bore 5.3 but some of the cylinders were pitted so not sure how much it's going to need to be bored. .005 at least but I told my machinist I want the smallest amount taken out. I will get a custom set of pistons made because trying to find a forged piston that doesn't want to bore out a lot seems impossible in the v8 world. My GSR had a .005 bore and it was easy getting pistons. I am running Mahle slugs on that with an Eagle H beam at stock compression and so far so good. Anyway thanks for the input.
(Old pic. All the stuff has been powder coated and looks nice and clean)
Last edited by FD3SEvo8; 02-21-2019 at 08:19 AM.
02-21-2019, 08:45 AM
#15
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I'd probably skip the LS6 cam unless you're getting it insanely cheap (and they're usually not anymore).
Any 22x/22x cam with make great power both N/A and boost in a 5.3.
Btw, stock gen 4 rods/pistons are the way to go for budget big power. $150-200 for a full set, can be had in flat tops, and will handle whatever you want to throw at it with proper ring gap and tune.
Even the stock gen 3 stuff is good for about 600whp. So many people are always so eager to go straight to forged stuff and end up unwarranting their blown budget.
Any 22x/22x cam with make great power both N/A and boost in a 5.3.
Btw, stock gen 4 rods/pistons are the way to go for budget big power. $150-200 for a full set, can be had in flat tops, and will handle whatever you want to throw at it with proper ring gap and tune.
Even the stock gen 3 stuff is good for about 600whp. So many people are always so eager to go straight to forged stuff and end up unwarranting their blown budget.
02-21-2019, 10:03 AM
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I'd probably skip the LS6 cam unless you're getting it insanely cheap (and they're usually not anymore).
Any 22x/22x cam with make great power both N/A and boost in a 5.3.
Btw, stock gen 4 rods/pistons are the way to go for budget big power. $150-200 for a full set, can be had in flat tops, and will handle whatever you want to throw at it with proper ring gap and tune.
Even the stock gen 3 stuff is good for about 600whp. So many people are always so eager to go straight to forged stuff and end up unwarranting their blown budget.
Any 22x/22x cam with make great power both N/A and boost in a 5.3.
Btw, stock gen 4 rods/pistons are the way to go for budget big power. $150-200 for a full set, can be had in flat tops, and will handle whatever you want to throw at it with proper ring gap and tune.
Even the stock gen 3 stuff is good for about 600whp. So many people are always so eager to go straight to forged stuff and end up unwarranting their blown budget.
The problem is, I need oversized pistons, and cant get oversized oem pistons. Summit Racing has a forged piston that fits the oem rod, but not sure on the quality. Any opinions on that?
As far as a cam, I got one picked out that should do nicely for NA then boost later. I talked to Comp yesterday and they helped me out with a spring/cam kit
02-21-2019, 11:44 AM
#17
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Summit is a sponsor here and can probably help you out if you message them directly. Texas Speed and a couple other sponsors will be able to get you any info or parts you need.
02-21-2019, 12:06 PM
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The downside is Summit Racing pistons are either dished or domed. I want flat tops lol
Last edited by FD3SEvo8; 02-21-2019 at 12:26 PM.
02-21-2019, 12:40 PM
#19
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Summit won't tell you who their suppliers are, but everything they've come out with lately has been top-shelf quality. They want to be known for quality, and if it's less expensive (you'll notice I did NOT say "cheap"), all the better! And they are in a position to do exactly that.
Last edited by G Atsma; 02-21-2019 at 03:15 PM.
02-21-2019, 01:10 PM
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Summit won't tell you who their suppliers are, but everything they've come out with lately has been top-shelf quality. They want to be known for quality, and if it's less expansive (you'll notice I did NOT say "cheap"), all the better! And they are in a position to do exactly that.