Boosted to NA 5.3
11-21-2019, 08:59 PM
#1
Boosted to NA 5.3 Hey guys,
I run a boosted 5.3 in my Miata for Time Attack road racing. I’ve been contemplating going NA for a variety of reasons. It’s a 2003 block, 6.098” H beam rods, 11.5:1 +2cc dome pistons, ARP main/head studs. It currently has a ls6 cam in it, new stock lifters, stock length Comp Cams push rods, upgraded rockers, I forgot what springs I put in it but they aren’t dual springs. 706 heads, stock valves.
it worked well boosted, made over 720 whp. The problem is I don’t need that much power, I would like to be around 500whp NA, we run 112 fuel in it. Is it possible with this bottom end? Obviously a proper cam, and probably cylinder heads? This car doesn’t get driven on the street we currently run it up to 7800rpm. If it’s possible to make that power I save 80+lbs of turbo ****, more reliable, less overall heat in the car to try and manage
I run a boosted 5.3 in my Miata for Time Attack road racing. I’ve been contemplating going NA for a variety of reasons. It’s a 2003 block, 6.098” H beam rods, 11.5:1 +2cc dome pistons, ARP main/head studs. It currently has a ls6 cam in it, new stock lifters, stock length Comp Cams push rods, upgraded rockers, I forgot what springs I put in it but they aren’t dual springs. 706 heads, stock valves.
it worked well boosted, made over 720 whp. The problem is I don’t need that much power, I would like to be around 500whp NA, we run 112 fuel in it. Is it possible with this bottom end? Obviously a proper cam, and probably cylinder heads? This car doesn’t get driven on the street we currently run it up to 7800rpm. If it’s possible to make that power I save 80+lbs of turbo ****, more reliable, less overall heat in the car to try and manage
11-21-2019, 10:18 PM
#2
TECH Senior Member
The bottom end WILL handle the power.
It DOES handle the present 720+ HP, so I'm not sure why you are asking the question.
A good pair of nicely ported 243/799 heads will handle the power, but you will need a serious cam with good mid range for road racing.
Call Cam Motion or TSP for good advice there.
It DOES handle the present 720+ HP, so I'm not sure why you are asking the question.
A good pair of nicely ported 243/799 heads will handle the power, but you will need a serious cam with good mid range for road racing.
Call Cam Motion or TSP for good advice there.
11-21-2019, 10:33 PM
#3
With current heads and bottom end I dont forsee 500whp being possible.
Not enough compression to run a cam large enough to spin high enough to make the power. Of course if you did have the rpm you'd need the cyl head to support it.
Not enough compression to run a cam large enough to spin high enough to make the power. Of course if you did have the rpm you'd need the cyl head to support it.
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Darth_V8r (11-22-2019)
11-22-2019, 07:51 AM
#5
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*insert DDnSPider surprised reaction at my suggesting boost here...*
11-22-2019, 08:14 AM
#6
The bottom end WILL handle the power.
It DOES handle the present 720+ HP, so I'm not sure why you are asking the question.
A good pair of nicely ported 243/799 heads will handle the power, but you will need a serious cam with good mid range for road racing.
Call Cam Motion or TSP for good advice there.
It DOES handle the present 720+ HP, so I'm not sure why you are asking the question.
A good pair of nicely ported 243/799 heads will handle the power, but you will need a serious cam with good mid range for road racing.
Call Cam Motion or TSP for good advice there.
I guess I was asking if it’s possible with the current compression ratio or if it was too low. If we kept the 11:5.1 pistons, got a better head and cam if it is was going to be possible. Seems like all the reading I’ve done suggests it’s not enough compression. I’ll give TSP today and see what they recommend. I did a dcr calculator this morning and with the ls6 cam it’s only 6.75:1. That’s seems terrible lol
11-22-2019, 08:31 AM
#8
Hey guys,
I run a boosted 5.3 in my Miata for Time Attack road racing. I’ve been contemplating going NA for a variety of reasons. It’s a 2003 block, 6.098” H beam rods, 11.5:1 +2cc dome pistons, ARP main/head studs. It currently has a ls6 cam in it, new stock lifters, stock length Comp Cams push rods, upgraded rockers, I forgot what springs I put in it but they aren’t dual springs. 706 heads, stock valves.
it worked well boosted, made over 720 whp. The problem is I don’t need that much power, I would like to be around 500whp NA, we run 112 fuel in it. Is it possible with this bottom end? Obviously a proper cam, and probably cylinder heads? This car doesn’t get driven on the street we currently run it up to 7800rpm. If it’s possible to make that power I save 80+lbs of turbo ****, more reliable, less overall heat in the car to try and manage
I run a boosted 5.3 in my Miata for Time Attack road racing. I’ve been contemplating going NA for a variety of reasons. It’s a 2003 block, 6.098” H beam rods, 11.5:1 +2cc dome pistons, ARP main/head studs. It currently has a ls6 cam in it, new stock lifters, stock length Comp Cams push rods, upgraded rockers, I forgot what springs I put in it but they aren’t dual springs. 706 heads, stock valves.
it worked well boosted, made over 720 whp. The problem is I don’t need that much power, I would like to be around 500whp NA, we run 112 fuel in it. Is it possible with this bottom end? Obviously a proper cam, and probably cylinder heads? This car doesn’t get driven on the street we currently run it up to 7800rpm. If it’s possible to make that power I save 80+lbs of turbo ****, more reliable, less overall heat in the car to try and manage
What boost are you running to make 720whp?
If you dont need that much power, can you not just turn the boost/timing down?
11-22-2019, 09:14 AM
#9
other option would be to go with a smaller turbo so it lights off quicker. This is an old on3 88mm, probably not suited for road racing
11-22-2019, 09:26 AM
#10
that was around 26lbs on old 5.3 stock dished pistons. It hasn’t been back to the dyno since we put the new bottom end together. But we have the timing turned down already because I raised the compression. Before I we had around 18-19° of timing in it. I think now it was somewhere around 12° I don’t remember exactly. But it’s a dog out of the corners now. That’s why I was thinking if it could make the power NA we could crank the timing back to it and get the drive off the corner again.
other option would be to go with a smaller turbo so it lights off quicker. This is an old on3 88mm, probably not suited for road racing
other option would be to go with a smaller turbo so it lights off quicker. This is an old on3 88mm, probably not suited for road racing
ok. I ask because I’m building a 5.3 right now and was thinking about going with a stock(ish) cam. I’d be happy with about 750whp but not at that boost pressure.
so you say the lower compression motor was more responsive because of added timing? If so, that’s good to know because I’m doing the opposite of what you did, I’m going from high compression to lower compression.
11-22-2019, 09:59 AM
#11
ok. I ask because I’m building a 5.3 right now and was thinking about going with a stock(ish) cam. I’d be happy with about 750whp but not at that boost pressure.
so you say the lower compression motor was more responsive because of added timing? If so, that’s good to know because I’m doing the opposite of what you did, I’m going from high compression to lower compression.
so you say the lower compression motor was more responsive because of added timing? If so, that’s good to know because I’m doing the opposite of what you did, I’m going from high compression to lower compression.
11-22-2019, 10:09 AM
#12
The problem is you have the wrong power adder. It's either larger cube NA or PD supercharger for road racing. 5.3 won't touch 520whp NA and have any kind of power under the curve. I would put a TVS 2300 on it and run 8-10psi. You will make the power under the curve you need for accelerating out of the corner.
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RyanRaduechel (11-22-2019)
11-22-2019, 10:29 AM
#13
The problem is you have the wrong power adder. It's either larger cube NA or PD supercharger for road racing. 5.3 won't touch 520whp NA and have any kind of power under the curve. I would put a TVS 2300 on it and run 8-10psi. You will make the power under the curve you need for accelerating out of the corner.
11-22-2019, 11:25 AM
#14
They love it!
that was around 26lbs on old 5.3 stock dished pistons. It hasn’t been back to the dyno since we put the new bottom end together. But we have the timing turned down already because I raised the compression. Before I we had around 18-19° of timing in it. I think now it was somewhere around 12° I don’t remember exactly. But it’s a dog out of the corners now. That’s why I was thinking if it could make the power NA we could crank the timing back to it and get the drive off the corner again.
other option would be to go with a smaller turbo so it lights off quicker. This is an old on3 88mm, probably not suited for road racing
other option would be to go with a smaller turbo so it lights off quicker. This is an old on3 88mm, probably not suited for road racing
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RyanRaduechel (11-24-2019)
11-22-2019, 04:19 PM
#15
ModSquad
iTrader: (6)
that was around 26lbs on old 5.3 stock dished pistons. It hasn’t been back to the dyno since we put the new bottom end together. But we have the timing turned down already because I raised the compression. Before I we had around 18-19° of timing in it. I think now it was somewhere around 12° I don’t remember exactly. But it’s a dog out of the corners now. That’s why I was thinking if it could make the power NA we could crank the timing back to it and get the drive off the corner again.
other option would be to go with a smaller turbo so it lights off quicker. This is an old on3 88mm, probably not suited for road racing
other option would be to go with a smaller turbo so it lights off quicker. This is an old on3 88mm, probably not suited for road racing
11-22-2019, 08:41 PM
#16
Could have heads ported and hollow valves put in by texas speed. Then have then spec a torquey cam for it and put a fast 102 ported on top Should make 420 wheel hp and 390 torque (guessing) and have a usuable power curve. 720whp seems like a lot to handle in a miatas for a road course...and I know enough about road course to understand that high hp cars aren't always the fastest.around the track
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G Atsma (11-22-2019)
11-24-2019, 09:36 PM
#18
If your set on going N/A and you want to get off the corners, I’d personally go with cubic inches. That car is begging for an aluminum engine to get weight off the nose. Look into an LS3 or an LS7 block with a set of heads that produce crazy fast velocity, cam the thing properly and spend money on valvetrain. Your just not gonna find the torque you want with a N/A 5.3 for road racing. Prolly not the answer you wanted, but it’s what I’d look into...
He wants more jams out of the corners not less, centri blowers are dogs down low, worse then a properly sized turbo.
They love it!
5.3 has zero chance of making 500whp. I would 100% ditch the 88mm for your needs as its way overkill. Get something like the next gen billet 78/75 run a bit lower boost and more timing, make for a more responsive combo overall.
They love it!
5.3 has zero chance of making 500whp. I would 100% ditch the 88mm for your needs as its way overkill. Get something like the next gen billet 78/75 run a bit lower boost and more timing, make for a more responsive combo overall.
Could have heads ported and hollow valves put in by texas speed. Then have then spec a torquey cam for it and put a fast 102 ported on top Should make 420 wheel hp and 390 torque (guessing) and have a usuable power curve. 720whp seems like a lot to handle in a miatas for a road course...and I know enough about road course to understand that high hp cars aren't always the fastest.around the track
this is the car
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31bad91 (11-25-2019)
11-24-2019, 11:15 PM
#20
TECH Addict
Helped a friend do a road C5 corvette with a standard crate 350 in it,, the recipe was to build a motor with RPM's ..
It was a 406 Sprint car buildup,, with the rev limited to 8200 (On the oval this motor would be turning 10,500)
Iron block aluminum heads, and the rotating assembly was scat/carillo/Mahle IIRC..
Good luck
It was a 406 Sprint car buildup,, with the rev limited to 8200 (On the oval this motor would be turning 10,500)
Iron block aluminum heads, and the rotating assembly was scat/carillo/Mahle IIRC..
Good luck