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Old 03-12-2010, 01:49 PM   #51
Equilibrium Tuning
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Quote:
Originally Posted by Homemade WRX View Post
Also why my solution is as simple as custom pistons which doesn't require shipping heads, although some deshrouding on a larger bore can be nice.

I actually tried the custom piston route before doing this. I've tuned a handful of hybrid builds set up with custom lower compression pistons and while the results were a bit better than setups with thicker HG's, these engines still didn't perform as well or as consistently as a full STI engine. I found they were still relatively knock prone on our pump gas and especially inconsistent with increased heat. They can also exhibit some drivability issues that I could not completely tune out.

The several engines that we've done with these CNC'd heads perform completely differently. They take a lot more advance, tend to be very knock resistant and consistent, and end up with extremely smooth drivability and power delivery. I literally had to completely re-work my base maps for these engines because the ignition profile is so drastically different. Its really tough to explain the magnitude of the difference without tuning and/or driving one of these setups.

Thanks
-- Ed
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Old 03-12-2010, 01:56 PM   #52
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Not to seem as I'm picking but what was your crown design on those custom pistons? just lower the compression ratio has proven to not be a solid answer. It yields a 'sloppy' combustion chamber for a kernel to grow. That is true. So I hope your judgement isn't just from the 'donut' dish design that is an off the shelf piston.

I'd be really interested in seeing your design criteria and data between the two tested methods, if it isn't proprietary. If so, I do understand. Just wondering why you are getting a different resultant from what I've experienced.
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Old 03-12-2010, 07:23 PM   #53
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Originally Posted by Homemade WRX View Post
Not to seem as I'm picking but what was your crown design on those custom pistons? just lower the compression ratio has proven to not be a solid answer. It yields a 'sloppy' combustion chamber for a kernel to grow. That is true. So I hope your judgement isn't just from the 'donut' dish design that is an off the shelf piston.

I'd be really interested in seeing your design criteria and data between the two tested methods, if it isn't proprietary. If so, I do understand. Just wondering why you are getting a different resultant from what I've experienced.
The custom pistons I tried before were a dish design similar to the factory style piston and similar to CP's off the shelf design as well. I have also tuned a couple engines with some custom JE's as well as Crawford's pistons for hybrid blocks. I believe these all share the general dish type design, but I could be wrong.

What kind of fuel are you guys using there? Maybe the variance in results we're seeing has more to do with the octane limitations we're running into with our fuel?

Thanks
-- Ed
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Old 03-12-2010, 07:32 PM   #54
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you're right. They are all extremely similar and completely different from mine...mine is closer to TWE or Axis
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Old 03-12-2010, 07:54 PM   #55
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Can we get some EJ20 before/after and EJ257 head pictures?
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Old 03-12-2010, 09:01 PM   #56
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Can we get some EJ20 before/after and EJ257 head pictures?
I'm working on that. Need to pay a visit to the machine shop

-- Ed
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Old 03-17-2010, 01:37 PM   #57
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bump.
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Old 03-19-2010, 06:09 PM   #58
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bump.
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Old 03-25-2010, 08:58 PM   #59
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Any pictures yet?
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Old 03-25-2010, 09:06 PM   #60
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Quote:
Originally Posted by Equilibrium Tuning View Post
Turnaround on blank heads is 1 week.

Thanks
-- Ed
much appreciated!
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Old 03-25-2010, 09:11 PM   #61
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where are those pictures?
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Old 03-26-2010, 12:15 AM   #62
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Damn I almost forgot!! We've been very busy here lately and I haven't had time to stop by the machine shop. I'll work on getting those up by the end of the week

-- Ed
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Old 03-26-2010, 10:17 AM   #63
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i had my K apart and found a bent and broken rod, bolt, bearing cap inside my oil pan.

im contemplating you giving me a head job! lol. but the price is kinda steep

j/k the price is fair imo, i just need to decide.


--keith
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Old 03-26-2010, 06:56 PM   #64
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ive had my hybrid motor together for a few months now, the car isnt completely done yet but I installed a brand new "stock" sti block with slightly pnp wrx heads with some internals. Im now feeling out the idea of taking it apart and doing pistons bearings and having the heads done. I NEED to see some stuff first. waiting patiently :-)
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Old 03-30-2010, 05:14 PM   #65
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What about those of us that want to run slightly higher compression in order to increase low-end torque? I was planning on rounding out the edges on my 2.0L heads and using stock head gaskets to gain the compression bump i wanted. Not an ideal way to do it, but it works.

This sounds like a bit more efficient way of achieving the hybrid swap, but will aftermarket STI higher compression pistons work in this application with 2.0L heads machined in this way? Since i am using stock head gaskets eaither way, i don't feel the quench area will be an issue for me.

I would also love to see the before and after pics...
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Old 03-31-2010, 03:32 AM   #66
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Originally Posted by Squidz View Post
What about those of us that want to run slightly higher compression in order to increase low-end torque? I was planning on rounding out the edges on my 2.0L heads and using stock head gaskets to gain the compression bump i wanted. Not an ideal way to do it, but it works.

This sounds like a bit more efficient way of achieving the hybrid swap, but will aftermarket STI higher compression pistons work in this application with 2.0L heads machined in this way? Since i am using stock head gaskets eaither way, i don't feel the quench area will be an issue for me.

I would also love to see the before and after pics...
High compression pistons would work just the same with these machined heads as they do with STI heads. The main benefit at this point would be the more efficient shape, and more appropriate diameter of the combustion chamber.

That being said, I really wouldn't recommend raising the CR unless you're planning on primarily running the car on race gas. The only major benefit of higher compression is off-boost torque, but there are a lot of potential draw-backs when running on pump gas.

Thanks
-- Ed
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Old 03-31-2010, 02:57 PM   #67
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^^^JE PIstons makes piston just for the Hybrid Swap. P/N 280089
I just bought them. But I am still going to take my heads and do some work on them.
So, Much Horror stories to this Hybrid Swap.
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Old 03-31-2010, 03:06 PM   #68
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Quote:
Originally Posted by Equilibrium Tuning View Post
High compression pistons would work just the same with these machined heads as they do with STI heads. The main benefit at this point would be the more efficient shape, and more appropriate diameter of the combustion chamber.

That being said, I really wouldn't recommend raising the CR unless you're planning on primarily running the car on race gas. The only major benefit of higher compression is off-boost torque, but there are a lot of potential draw-backs when running on pump gas.

Thanks
-- Ed
Yeah, as an autocross car, i really need off-boost torque. Even with my EVO III (which is currently being converted to an HTA-68), i had absolutely no power below 3500 RPM. I mean, that was with my 2.0L motor...so i'm sure the better turbo and the addition of a 2.5L/head porting/cams will make a substantial difference in low-end torque. I just want to make sure i do everything i can with this build to get the low-end power i'm looking for.

I was planning on running E85 on the higher compression setup. Anyone have any ideas/opinions on that? Either way, i think this machining is a very good idea for what i'm trying to do.
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Old 04-06-2010, 06:16 PM   #69
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Quote:
Originally Posted by lcjarrett View Post
^^^JE PIstons makes piston just for the Hybrid Swap. P/N 280089
I just bought them. But I am still going to take my heads and do some work on them.
So, Much Horror stories to this Hybrid Swap.
Those pistons will certainly bring the compression ratio down, but it doesn't change the fact that the combustion chamber in the heads is too small and introduces sharp edges.

I've tuned a couple hybrids with the lower comp JE pistons previously and they tend to run just like the ones with thicker head gaskets.

Thanks
-- Ed
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Old 04-06-2010, 06:20 PM   #70
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Quote:
Originally Posted by Squidz View Post
Yeah, as an autocross car, i really need off-boost torque. Even with my EVO III (which is currently being converted to an HTA-68), i had absolutely no power below 3500 RPM. I mean, that was with my 2.0L motor...so i'm sure the better turbo and the addition of a 2.5L/head porting/cams will make a substantial difference in low-end torque. I just want to make sure i do everything i can with this build to get the low-end power i'm looking for.

I was planning on running E85 on the higher compression setup. Anyone have any ideas/opinions on that? Either way, i think this machining is a very good idea for what i'm trying to do.
On E85, the higher compression should be fine, but I would still recommend getting the combustion chamber right and using high comp pistons. There's a HUGE difference in off boost, low rpm torque going from the 2.0 to a 2.5l, and the boost threshold is moved significantly lower as well. But if you never plan on running the car on pump gas, the higher compression may help a bit as well.

Thanks
-- Ed
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Old 04-06-2010, 06:37 PM   #71
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wheres the pics????
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Old 04-06-2010, 06:39 PM   #72
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Any pictures yet?
.....
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Old 04-06-2010, 07:05 PM   #73
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Sorry guys... just been ridiculous over here the past couple weeks and I haven't had a chance to get to the machine shop with a camera.

We have a couple orders for these heads in the next few weeks, so I'll get pictures of those at the latest.

Thanks
-- Ed
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Old 04-06-2010, 09:05 PM   #74
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whats your opinion on using wrx heads with the crack by the plug hole?
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Old 04-06-2010, 09:47 PM   #75
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whats your opinion on using wrx heads with the crack by the plug hole?
We generally recommend not using them if they have that crack. We find about half of the heads we pull off do have a crack developing there. IMO that's not ideal for a performance situation and especially not if the engine is going to get pushed at all.

-- Ed
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