How much power before I need pistons? What about lower compression pistons?
12-04-2016, 03:14 PM
#1
Burning Brakes
Thread Starter
How much power before I need pistons? What about lower compression pistons?
So I currently have A&A's Ti blower with a 3.6" pulley. Single nozzle methanol and long tube headers, as well.
When I had it tuned and dynoed, it did 518/467 actual to the wheels (no oxygen here), and 9.5-10psi peak boost was seen.
I think the 3.47" pulley will max out the blower's RPM, and will probably boost around 12psi?
At what power levels will I need forged pistons / rods? Why are low-compression pistons used for boosted applications and how do they affect the amount of pressure seen in the manifold?
Is anybody spinning a Ti blower to the max here? How much power are you making, (either SAE or actual w/ altitude)?
When I had it tuned and dynoed, it did 518/467 actual to the wheels (no oxygen here), and 9.5-10psi peak boost was seen.
I think the 3.47" pulley will max out the blower's RPM, and will probably boost around 12psi?
At what power levels will I need forged pistons / rods? Why are low-compression pistons used for boosted applications and how do they affect the amount of pressure seen in the manifold?
Is anybody spinning a Ti blower to the max here? How much power are you making, (either SAE or actual w/ altitude)?
Last edited by joemosfet; 12-04-2016 at 03:21 PM. Reason: add more info
12-04-2016, 06:05 PM
#2
Team Owner
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ttt
Man believe me call it a day with the car as is.. Unless you want to go all out with cam, rods, piston,. Then when you go to this you will be looking at clutch, are auto trans, converter, axle's. This is not all of the parts you will be looking at breaking down the road.
At your rwhp level now per say will be safe to a big point here, and still out run and be able to play with 99% of the cars out on the road.
Don't think about hp now look at getting to REALLY drive the car and being able to get the car to hook up for you. Good set of street D/R. If you do this believe me you will be able to beat a lot of guys with cars with more horse power than what you are showing here in your graft.
At your rwhp level now per say will be safe to a big point here, and still out run and be able to play with 99% of the cars out on the road.
Don't think about hp now look at getting to REALLY drive the car and being able to get the car to hook up for you. Good set of street D/R. If you do this believe me you will be able to beat a lot of guys with cars with more horse power than what you are showing here in your graft.
Last edited by robert miller; 12-04-2016 at 06:09 PM.
12-04-2016, 06:31 PM
#3
Burning Brakes
Thread Starter
^Widebody is on my list so I can squeeze s'more rubber under there. I wouldn't mind doing cam, rods, pistons, that sounds like fun. I've already contacted a couple of shops around here to handle my honing and balancing work, I am just wonder at what power level I need to actually pull that trigger.
12-04-2016, 06:45 PM
#4
Racer
Im spinning my V3 Ti to the max 7.65 lower and 3.47 upper pulley. I think 6750 to 6800 RPM is max impeller speed 52,000. Right at 11.6 to 11.8lbs of boost. Im on Forged stock compression pistons.
12-04-2016, 07:41 PM
#5
Le Mans Master
To the OP. That magically Number most will tell you is 700 wheel and you need to start thinking about pistons. I ran my car for 2 years at 700 wheel on stock bottom end.
However...... it all depends on the tune.
However...... it all depends on the tune.
Last edited by C7&7; 12-04-2016 at 07:43 PM.
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joemosfet (12-04-2016)
12-04-2016, 08:42 PM
#6
Burning Brakes
why is you dyne number low? with those mods you should be easy around the 600whp
12-04-2016, 11:59 PM
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12-05-2016, 12:31 PM
#10
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St. Jude Donor '15
Nothing good IMO. More boost to make the same power, less torque, less efficiency pretty much everywhere. Lowering compression isn't what you want. Stronger pistons... maybe.
Unless you're going for like 900-1000+ then don't even think about it IMO
Unless you're going for like 900-1000+ then don't even think about it IMO
Last edited by schpenxel; 12-05-2016 at 12:35 PM.
12-05-2016, 12:34 PM
#11
Le Mans Master
Depends on how far you want to go with it. You can buy a completely forged shortblock these days for <$5000 if you utilize the stock crank which is good for about 1000 wheel. Thats a custom lower compression piston and a good rod. Or you can do the drop in pistons for ~$1200 plus labor but you're keeping the higher compression and not adding the insurance of a better rod.
12-05-2016, 12:58 PM
#12
Drifting
Well. You have two choices. You can do the drop in pistons that are identical size and weight and compression with stock. Or you can do a custom piston to lower compression and you will have to rebalance the rotating assembly. If you choose option two then you might as well spend the additional money to do a good rod while you're at it.
Depends on how far you want to go with it. You can buy a completely forged shortblock these days for <$5000 if you utilize the stock crank which is good for about 1000 wheel. Thats a custom lower compression piston and a good rod. Or you can do the drop in pistons for ~$1200 plus labor but you're keeping the higher compression and not adding the insurance of a better rod.
Depends on how far you want to go with it. You can buy a completely forged shortblock these days for <$5000 if you utilize the stock crank which is good for about 1000 wheel. Thats a custom lower compression piston and a good rod. Or you can do the drop in pistons for ~$1200 plus labor but you're keeping the higher compression and not adding the insurance of a better rod.
What's the end game? With fueling support and the drop in pistons you could get up well 700s whp... If you're going to drop the compression and have the whole assembly rebalanced you might as well do it right with a forged short and pistons/rods.
With the later option always be mindful of the accessory modifications which may be needed. Clutches, driveline, fuel etc..
12-05-2016, 08:06 PM
#13
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Well. You have two choices. You can do the drop in pistons that are identical size and weight and compression with stock. Or you can do a custom piston to lower compression and you will have to rebalance the rotating assembly. If you choose option two then you might as well spend the additional money to do a good rod while you're at it.
Depends on how far you want to go with it. You can buy a completely forged shortblock these days for <$5000 if you utilize the stock crank which is good for about 1000 wheel. Thats a custom lower compression piston and a good rod. Or you can do the drop in pistons for ~$1200 plus labor but you're keeping the higher compression and not adding the insurance of a better rod.
Depends on how far you want to go with it. You can buy a completely forged shortblock these days for <$5000 if you utilize the stock crank which is good for about 1000 wheel. Thats a custom lower compression piston and a good rod. Or you can do the drop in pistons for ~$1200 plus labor but you're keeping the higher compression and not adding the insurance of a better rod.
12-05-2016, 08:13 PM
#14
Le Mans Master
12-06-2016, 07:17 AM
#16
Le Mans Master
12-06-2016, 10:40 AM
#18
Le Mans Master
12-06-2016, 11:57 AM
#19
Burning Brakes
Thread Starter
Well, you can't buy a shortblock without a crank - a shortblock, by definition, includes a balanced rotating assembly, and is fully assembled.
Unless you're suggesting removing the shortblock's new crank and putting in the stock crank? Wouldn't that require a re-balancing? Not to mention the disassembly and reassembly of the shortblock... I mean that's the purpose of buying a shortblock, is that the rotating assembly is already balanced and assembled.
Now, that being said, parts can be had, new forged pistons and rods and pins, rings, new bearings, mains, studs, and maybe even an aluminum block can be had for less than 5k, but then add in the time that it takes to tear down the old bottom end to pull out the crank, and then get it balanced and assembled int he new block? Not to mention the various LT1 things that need to be done with the oil squirters, etc.
Will the price still be less than 5k? Or is it worth spending the 5500+ or so for a fully assembled and balanced short block with crank?
Unless you're suggesting removing the shortblock's new crank and putting in the stock crank? Wouldn't that require a re-balancing? Not to mention the disassembly and reassembly of the shortblock... I mean that's the purpose of buying a shortblock, is that the rotating assembly is already balanced and assembled.
Now, that being said, parts can be had, new forged pistons and rods and pins, rings, new bearings, mains, studs, and maybe even an aluminum block can be had for less than 5k, but then add in the time that it takes to tear down the old bottom end to pull out the crank, and then get it balanced and assembled int he new block? Not to mention the various LT1 things that need to be done with the oil squirters, etc.
Will the price still be less than 5k? Or is it worth spending the 5500+ or so for a fully assembled and balanced short block with crank?
12-06-2016, 12:15 PM
#20
I'm Batman..
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Well, you can't buy a shortblock without a crank - a shortblock, by definition, includes a balanced rotating assembly, and is fully assembled.
Unless you're suggesting removing the shortblock's new crank and putting in the stock crank? Wouldn't that require a re-balancing? Not to mention the disassembly and reassembly of the shortblock... I mean that's the purpose of buying a shortblock, is that the rotating assembly is already balanced and assembled.
Now, that being said, parts can be had, new forged pistons and rods and pins, rings, new bearings, mains, studs, and maybe even an aluminum block can be had for less than 5k, but then add in the time that it takes to tear down the old bottom end to pull out the crank, and then get it balanced and assembled int he new block? Not to mention the various LT1 things that need to be done with the oil squirters, etc.
Will the price still be less than 5k? Or is it worth spending the 5500+ or so for a fully assembled and balanced short block with crank?
Unless you're suggesting removing the shortblock's new crank and putting in the stock crank? Wouldn't that require a re-balancing? Not to mention the disassembly and reassembly of the shortblock... I mean that's the purpose of buying a shortblock, is that the rotating assembly is already balanced and assembled.
Now, that being said, parts can be had, new forged pistons and rods and pins, rings, new bearings, mains, studs, and maybe even an aluminum block can be had for less than 5k, but then add in the time that it takes to tear down the old bottom end to pull out the crank, and then get it balanced and assembled int he new block? Not to mention the various LT1 things that need to be done with the oil squirters, etc.
Will the price still be less than 5k? Or is it worth spending the 5500+ or so for a fully assembled and balanced short block with crank?