9:1 Compression Piston Pricing
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From: Southwest Florida
I guess we could consider this a half assed group buy. We have finalized 9:1 compression pistons that are compatible with high duration cams. They are rated for 9:1 compression. The current spec for piston rings is 1mm, 1.75mm, and 2.8mm (oil seal).
Piston rings are not included, they will be an extra $200 approx. You can purchase rings from whomever you like, but my shop will give you a recommendation based on the application.
The pistons have a place in line at JE right now, we are looking at about 2 weeks before they are fabricated. Up until the day they are fabbed we can changed the quantity of the order. Once they start production we have to get another spot in line before they can be produced again. The idea is that once they setup the order it's no big deal to burn a bunch more. Producing more pistons will help reduce the overall cost of the project (which is the only reason why I am posting here.)
The price is $175 per piston, or $700 for a set.
Cam pricing info will be available at a later time (2-3 weeks) if anyone is interested. I assume you guys will be waiting until I finish my engine before you want to buy cams. The relationship with the cam company allows for the shop to turn around cams in about a week and a half or so...
If you guys are interested contact me with any questions, or post here.
PS: If anyone is interested in doing a high performance NA F20C we have some good experience now
(I think it would kick ass to do an N/A F20C!!)
PPS: I am not profiting on this at all, this is purely to try and save me money on pistion R&D...
Piston rings are not included, they will be an extra $200 approx. You can purchase rings from whomever you like, but my shop will give you a recommendation based on the application.
The pistons have a place in line at JE right now, we are looking at about 2 weeks before they are fabricated. Up until the day they are fabbed we can changed the quantity of the order. Once they start production we have to get another spot in line before they can be produced again. The idea is that once they setup the order it's no big deal to burn a bunch more. Producing more pistons will help reduce the overall cost of the project (which is the only reason why I am posting here.)
The price is $175 per piston, or $700 for a set.
Cam pricing info will be available at a later time (2-3 weeks) if anyone is interested. I assume you guys will be waiting until I finish my engine before you want to buy cams. The relationship with the cam company allows for the shop to turn around cams in about a week and a half or so...
If you guys are interested contact me with any questions, or post here.
PS: If anyone is interested in doing a high performance NA F20C we have some good experience now
(I think it would kick ass to do an N/A F20C!!)PPS: I am not profiting on this at all, this is purely to try and save me money on pistion R&D...
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From: Houston
What are everyone's thoughts about going that low, 9.1? How much boost would you need to have to make up for the lowered compression? I thought 10.1 was what you were aiming for...or have you up'ed your boost goal as well?
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Joined: Feb 2001
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From: You wish
Wes,
A drop from 11:1 to 10:1 will cost you about 1.5-2% power, all things remaining equal. A further drop from 10:1 to 9:1 should be another 2-3%. So, you're looking at about a 5% drop in power if you don't up the boost - or about 15 hp for the kind of numbers you guys are running.
The upside is that if the maximum boost on pump gas was 7 psi before, you were running an effective compression ratio of about 16.5 at full boost. To get to that same level with a 9:1 ratio, you'll be able to run around 12-13 psi. By my calcs, if 6-7 psi is good for 290-300 wheel hp, then 12-13 psi should get you to about 370 or so, then take away the 5% on the compression side, and you've got about 350 wheel on pump gas (I think a little more, but we'll see).
BTW, just so you guys know, 350+ to the wheels on pump gas is awesome. Some very well built, race Mitsu 2 liters running 18-19 psi with total MoTec and everything make about 400 to the wheels on pump gas (and about 350-400 lbs-ft). If you guys can get to over 350 on 91 octane without ECU, cams, head, etc. you're doing very, very well.
Wes, the drop in compression will hurt you more because you can't spool up the boost as soon as a turbo, thus you'll be a little flat below 3000-4000 rpm.
UL
A drop from 11:1 to 10:1 will cost you about 1.5-2% power, all things remaining equal. A further drop from 10:1 to 9:1 should be another 2-3%. So, you're looking at about a 5% drop in power if you don't up the boost - or about 15 hp for the kind of numbers you guys are running.
The upside is that if the maximum boost on pump gas was 7 psi before, you were running an effective compression ratio of about 16.5 at full boost. To get to that same level with a 9:1 ratio, you'll be able to run around 12-13 psi. By my calcs, if 6-7 psi is good for 290-300 wheel hp, then 12-13 psi should get you to about 370 or so, then take away the 5% on the compression side, and you've got about 350 wheel on pump gas (I think a little more, but we'll see).
BTW, just so you guys know, 350+ to the wheels on pump gas is awesome. Some very well built, race Mitsu 2 liters running 18-19 psi with total MoTec and everything make about 400 to the wheels on pump gas (and about 350-400 lbs-ft). If you guys can get to over 350 on 91 octane without ECU, cams, head, etc. you're doing very, very well.
Wes, the drop in compression will hurt you more because you can't spool up the boost as soon as a turbo, thus you'll be a little flat below 3000-4000 rpm.
UL
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From: Southwest Florida
This isn't a "keep us posted" thread, this is an "ok it's ready lets go" thread our experience indicates that a drop in 1 point of compression yields approx 20 hp loss, in a boosted application. I am thinking 15 psi at 9:1 is pushing it, but I believe it's possible. We are going to run it at 12 psi to start with and see what results we can get. We're shooting for >=400 to the ground at 12psi w/ head work, cams, etc etc..
I guess this thread would be more interesting to people planning on going to a turbo, or current turbo people. Superchargers may have some trouble running at 9:1 cause of the boosting nature... at 9:1 you should be able to go with that 12 psi pulley at 9000.. you'd have to cool it at that point.
our experience indicates that a drop in 1 point of compression yields approx 20 hp loss, in a boosted application. I am thinking 15 psi at 9:1 is pushing it, but I believe it's possible. We are going to run it at 12 psi to start with and see what results we can get. We're shooting for >=400 to the ground at 12psi w/ head work, cams, etc etc..I guess this thread would be more interesting to people planning on going to a turbo, or current turbo people. Superchargers may have some trouble running at 9:1 cause of the boosting nature... at 9:1 you should be able to go with that 12 psi pulley at 9000.. you'd have to cool it at that point.
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From: Johnson City
CJB 80,
Sorry man I would buy now to help you absorb R&D costs but I won't be put on the list over at speedcraft until the fall... trying to get the pinnacle brake setup as well. Anyways... I was wondering if there are any issues with the new rings and the special cylinder liners in the engine. Are they going to use different material or anything (forgive me I know very little about swapping pistons) that might cause more wear due to the interaction of different materials??
Thanks,
Charles
Sorry man I would buy now to help you absorb R&D costs but I won't be put on the list over at speedcraft until the fall... trying to get the pinnacle brake setup as well. Anyways... I was wondering if there are any issues with the new rings and the special cylinder liners in the engine. Are they going to use different material or anything (forgive me I know very little about swapping pistons) that might cause more wear due to the interaction of different materials??
Thanks,
Charles
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From: Southwest Florida
The issues relate to piston ring material mainly and that's something that we're still addressing. There are various issues with it mainly due to heat and how 'springy' the rings are..
Chris
Chris
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sorry to bring up an old thread, but i would love to hear continued discussion on this topic...
i've heard that the drop in one compression point yields a 250 rpm increase in turbo lag. so for example, if at 11:1 compression, you spooled to x psi at 3500, at 9:1, you would spool to x psi at 4000. any truth to this notion?
Chris, whats the info on your car currently? everything back together yet?
i've heard that the drop in one compression point yields a 250 rpm increase in turbo lag. so for example, if at 11:1 compression, you spooled to x psi at 3500, at 9:1, you would spool to x psi at 4000. any truth to this notion?
Chris, whats the info on your car currently? everything back together yet?