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Old 11-18-2009, 05:02 PM   #26
john 1badSTI
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Originally Posted by Maxwell Power View Post
Are you going to have the combustion chambers in the head modified to improve power and reliability?

People try arguing with us all the time about how much better it is to fix the combustion chamber on hybrid builds. Well we proved it. 40whp more on pump gas than the previous tune on meth/water injection.

Please, do the work. Not doing it is what causes so many hybrids to fail. Even an awesome tune can't overcome the poor mechanics of the 2L chamber on a 2.5L bore.
+++1 it is essential like Maxwel said --if you want your hybrid to live and make good power you have to have the chambers opened up to match the larger bore of the 2.5--I CANNOT STRESS THIS ENUFF--IT NEEDS TO BE DONE.
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Old 11-18-2009, 06:41 PM   #27
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what about an ej255 with ej255 heads and ej205 cams and ej205 cam gears with ej255 valves, springs, and retainers? was gonna do the hybrid but i have the ej255 heads so mide as well use them instead of selling them. save the avcs stuff for a later date.

i hear that its a bunch of bs about the ej257 not working well with ej205 heads though.

i bet there are thousands of working hybrids.
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Old 11-18-2009, 06:43 PM   #28
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There are plenty of hybrids that hold up very well.
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Old 11-18-2009, 06:46 PM   #29
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i hear that its a bunch of bs about the ej257 not working well with ej205 heads though.

i bet there are thousands of working hybrids.

it works.

It's just not reliable. I get calls everyday from people with hybrids that blew up. It is very common to experience excessive detonation with a hybrid.

besides, 350 bucks for chamber mods that gain power and reliability should be a no brainer.


You can lead a horse to water, but you can't make him drink. Especially if he's a really cheap horse and the water is 5 cents a gallon.
That's how I feel on a daily basis. I have blown up more of my own engines than I want to remember, done TONS of R&D, design and every hybrid you can think of. It's so frustrating when you give advice that is VERY sound advice and people want to argue about it.


Do it, you won't regret it.

Don't do it, and you will.

[/my advice]
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Old 11-18-2009, 07:22 PM   #30
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^^^++1 I heard that---I know exactly what you mean Maxwell.
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Old 11-18-2009, 07:35 PM   #31
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I'm very thankful for the advice - as I said before, right now it's not up to me, it's up to IAG.
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Old 11-18-2009, 07:38 PM   #32
john 1badSTI
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good luck with your build and don't hesitate to ask questions about anything you are not sure of.
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Old 11-18-2009, 08:01 PM   #33
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Originally Posted by STI_KLR View Post
I'm very thankful for the advice - as I said before, right now it's not up to me, it's up to IAG.
tell them to ship me the heads. It's your engine, your car and your wallet. Tell them to build it how you want it, not them.
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Old 11-19-2009, 12:10 AM   #34
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i am actually trying to research this before i build. i am new to engine building and like to understand completely before i committ. i don't completely understand where the problem lies.

far as i know head work is more like 2 grand...not 350$.

i have a set of ej255 avcs heads that match my ej257 block. i also have an 04 wrx longblock. i took it apart and cleaned the heads up.

so i am up in the air about using the ej255 heads with the wrx cams and wrx cam gears or selling the avcs heads complete and just using the wrx heads with the wrx cams.

i'm bolting on a rotated gt30r perrin kit with spec c tgv, 8mm phenolic spacer, dw750's, prodrive 3 port boost controler, 44mm tial ewg dumpt to downpipe, turbo xs parallel rails, forge 100% blow off, 3 inch turbo back, walbro 255, lightweight crank pulley,organic stage 1 clutch, borla unequal length header, wrx top mount (rotated front mount to follow), cosworth pistons, cosworth bearings, arp heads studs, arp block bolts, cosworth head gasket, ej255 rods, ej255 crank, to an ej257 block. hooked up to my 02 wrx intake manifold/harness. ecutek tune by dave at rallispec.

so i could use the wrx heads/cams/valves springs ect... on the ej257 and have a hybrid that is unreliable? i could make some decent coin off the sale of the avcs heads.

or i could use the matching ej255 heads with the ej257 with wrx cams and cam gears and what?

what would the benefits of the ej255 heads be? i have considered bigger non-avcs cams
for the ej255 heads.

i was wondering how the motor would run with small wrx cams and big late hittin turbo.

i'll be running it on an sti ra gear set so at this point i won't be tuning above 350 torque 350 horse. (plus my injectors are small)

all advice is appreciated?

did i jack this thread? sorry bro.
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Old 11-19-2009, 12:42 AM   #35
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The EJ205 heads have a smaller bore than the EJ257/EJ255 shortblock. That means that the 'dome' of the combustion chamber doesn't fit perfectly on top of the piston. So rather than the combustion chamber being a smooth dome, there's a sharp edge that is a detonation hotspot and screws up the combustion.

$300 gets you machining to match the dome of the head with the larger bore of the shortblock, making the engine far less prone to detonation per Maxwell Power.

$3000 gets you lots of machining of the intake and exhaust ports (what people usually refer to as 'headwork'). That's not what Maxwell is talking about. He's referring to a much simpler, much cheaper procedure specific to the hybrid engine rather than generic expensive head work.
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Old 11-19-2009, 01:14 AM   #36
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Originally Posted by Checkers View Post
The EJ205 heads have a smaller bore than the EJ257/EJ255 shortblock. That means that the 'dome' of the combustion chamber doesn't fit perfectly on top of the piston. So rather than the combustion chamber being a smooth dome, there's a sharp edge that is a detonation hotspot and screws up the combustion.

$300 gets you machining to match the dome of the head with the larger bore of the shortblock, making the engine far less prone to detonation per Maxwell Power.

$3000 gets you lots of machining of the intake and exhaust ports (what people usually refer to as 'headwork'). That's not what Maxwell is talking about. He's referring to a much simpler, much cheaper procedure specific to the hybrid engine rather than generic expensive head work.
checkers is right.
Optimizing your combustion chamber is 350. Optimizing your ports is 1300.

the chamber is the most important for reliability and makes better power.
Ports are important for making even more power.
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Old 11-19-2009, 07:50 AM   #37
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Quote:
Originally Posted by maxpowr View Post
i am actually trying to research this before i build. i am new to engine building and like to understand completely before i committ. i don't completely understand where the problem lies.

far as i know head work is more like 2 grand...not 350$.

i have a set of ej255 avcs heads that match my ej257 block. i also have an 04 wrx longblock. i took it apart and cleaned the heads up.

so i am up in the air about using the ej255 heads with the wrx cams and wrx cam gears or selling the avcs heads complete and just using the wrx heads with the wrx cams.

i'm bolting on a rotated gt30r perrin kit with spec c tgv, 8mm phenolic spacer, dw750's, prodrive 3 port boost controler, 44mm tial ewg dumpt to downpipe, turbo xs parallel rails, forge 100% blow off, 3 inch turbo back, walbro 255, lightweight crank pulley,organic stage 1 clutch, borla unequal length header, wrx top mount (rotated front mount to follow), cosworth pistons, cosworth bearings, arp heads studs, arp block bolts, cosworth head gasket, ej255 rods, ej255 crank, to an ej257 block. hooked up to my 02 wrx intake manifold/harness. ecutek tune by dave at rallispec.

so i could use the wrx heads/cams/valves springs ect... on the ej257 and have a hybrid that is unreliable? i could make some decent coin off the sale of the avcs heads.

or i could use the matching ej255 heads with the ej257 with wrx cams and cam gears and what?

what would the benefits of the ej255 heads be? i have considered bigger non-avcs cams
for the ej255 heads.

i was wondering how the motor would run with small wrx cams and big late hittin turbo.

i'll be running it on an sti ra gear set so at this point i won't be tuning above 350 torque 350 horse. (plus my injectors are small)

all advice is appreciated?

did i jack this thread? sorry bro.
yea you did its not yours its his. So out of respect you should make your own.
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Old 11-19-2009, 08:04 AM   #38
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That poor car has lived a hard life. I hope you get it sorted out soon.

It sounds like the headwork advice is something you should look into, if IAG doesnt want to do it, find someone that will.
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Old 11-19-2009, 08:51 AM   #39
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i didn't mean to jack but this info is relavent to sti klrs build. thanks for the info boys.
just seems like selling myself short to do the chambers and not the valves but at this point cash is beginning to slow me down. i think it makes more sense for me to use the ej255 heads. i'll keep an eye on this thread if i can offer any input.
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Old 11-19-2009, 12:00 PM   #40
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That poor car has lived a hard life. I hope you get it sorted out soon.
****, tell me about it man haha February was the beginning of the dark ages.
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Old 11-19-2009, 01:07 PM   #41
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anyone have pics of chamber work?
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Old 11-19-2009, 01:29 PM   #42
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I should be getting a call this afternoon from IAG about the heads - Rick saw this thread and they're holding up with the heads until we chat.
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Old 11-20-2009, 12:04 AM   #43
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Nice build... but why the MBC??? Seems like your more than willing to pay the price of good parts so why the MBC??? Just wondering...
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Old 11-20-2009, 12:12 AM   #44
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Whats wrong with a MBC? I have one recommend by one of the best tuners in the game Phil at Element tuning....
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Old 11-20-2009, 01:08 AM   #45
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Nice build... but why the MBC??? Seems like your more than willing to pay the price of good parts so why the MBC??? Just wondering...
What do you prefer over the MBC?

The Hallman unit is BY FAR one of the best MBC's out there. On the new setup, I'm going to be utilizing a hybrid setup - running the EBCS and MBC together.
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Old 11-20-2009, 02:38 AM   #46
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Default 20k chamber work pics

Here are a couple of before and after pics of the ej20k heads that are on my ej257 short block, showing what the chamber work looks like that Maxwell Power Services did. Illustrates what he is talking about and may help you with your decision.

Before



After

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Old 11-20-2009, 09:13 AM   #47
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Originally Posted by kleinkid View Post
Here are a couple of before and after pics of the ej20k heads that are on my ej257 short block, showing what the chamber work looks like that Maxwell Power Services did. Illustrates what he is talking about and may help you with your decision.

Before



After

finally.... a picture is worth a 1000 words or dollars perhaps..

i have often heard of 'unshrouding the valves' .. now i see.. i wonder what the cylinder head volume change is.. around 5cc?
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Old 11-20-2009, 09:23 AM   #48
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Quote:
Originally Posted by kleinkid View Post
Here are a couple of before and after pics of the ej20k heads that are on my ej257 short block, showing what the chamber work looks like that Maxwell Power Services did. Illustrates what he is talking about and may help you with your decision.

Before



After

finally.... a picture is worth a 1000 words or dollars perhaps..

i have often heard of 'unshrouding the valves' .. now i see.. i wonder what the cylinder head volume change is.. around 5cc?

another question.. some folks say the 2.5 cylinder diameter is larger than the circle you see in the pics. so they say.. lay a 2.5 head gasket over the 2.0 head, scribe the circle and then remove metal from the head so that the 2.0 head ends up being the same diameter as the 2.5 block. no 'overhang'..

it appears from above that either a) the 2.0 'circle' is the same diameter as the 2.5 cylinder or b) the so-called 'overhang' issue is bogus..

comments?
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Old 11-20-2009, 09:35 AM   #49
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The 2.5 bore is 99.5mm where the 2.0 bore is 92.? mm. So yes the 'circle' on the 2.0 heads is smaller.
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Old 11-20-2009, 10:38 AM   #50
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Quote:
Originally Posted by SonicR1 View Post
Nice build... but why the MBC??? Seems like your more than willing to pay the price of good parts so why the MBC??? Just wondering...
Nothing wrong with an MBC...in fact for a lot of people a factory controlled 3-port is MUCH more chaotic and unpredictable than an MBC on an EWG.
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