I have a ej257 being built with the crawford s3l internals (pauter long rods, cp 100mm pistons with 8.7:1 compression, arp head studs). It's being polished and balanced, but realistically, can I rev it to the 8k redline that these heads would normally run at?

What should I set redline at to have a good reliable setup?

I have a ej257 being built with the crawford s3l internals (pauter long rods, cp 100mm pistons with 8.7:1 compression, arp head studs). It's being polished and balanced, but realistically, can I rev it to the 8k redline that these heads would normally run at?

What should I set redline at to have a good reliable setup?

I would wait and see where you are making power.. No use in reving it all the way out if power drops off hard. With that bottom end you should be able to rev, but again you will need to figure out how far is worth going.

Try revving to 10,000 rpms and see if it works. If not, then go lower.....

seriously, did you beef up the valve train? that is what lets you rev high or not...not the heads...AFAIK heads are passive.

V7 sti heads (and valvetrain) can run 8000rpm. They did it for 15k miles on my ej207. I'm curious if people have run the ej257 at 8000rpms.

The point about not making power up over 7000rpms was something I considered and wanted to investigate a bit on the dyno, but I don't know if it's really safe to do...

you can run the ej257 to and above 8000 as long as the bottem end is modded for it

I ran mine at 7500-7600 for quite awhile with no ill effects. Stock EJ257 block with V8 RA heads. Generally though you aren't making much more power after about 7000 rpm anyways, so the benefits of running it to 8000 rpm are probably not worth the stress on the engine.

8k should not be a problem for your setup. I would be more worried about making the quench area match the 2.5l heads that came on the 2.5 bottom end. If you go in there with your smaller 2.0l quench area you may need to retard your timing more to keep the det at bay. The quench area is going to affect the way the flame front is going to propagate so you want this to be right. From what I've read, people who are reworking the quench area are getting more timing out of their engines. I'll be going this route very soon. I'll keep you all posted.

8k should not be a problem for your setup. I would be more worried about making the quench area match the 2.5l heads that came on the 2.5 bottom end. If you go in there with your smaller 2.0l quench area you may need to retard your timing more to keep the det at bay. The quench area is going to affect the way the flame front is going to propagate so you want this to be right. From what I've read, people who are reworking the quench area are getting more timing out of their engines. I'll be going this route very soon. I'll keep you all posted.
I have to admit I'm really not familiar with what the quench area is exactly... Could you elaborate on this or point me in the direction of a resource that could? How does one rectify this problem?

I have to admit I'm really not familiar with what the quench area is exactly... Could you elaborate on this or point me in the direction of a resource that could? How does one rectify this problem?


yes, please elaborate!!!!! I am getting ready to slap some wrx heads on a 257 block, and if there's some dremel work I can do to improve things, I'll sure do it!!!

8k should not be a problem for your setup. I would be more worried about making the quench area match the 2.5l heads that came on the 2.5 bottom end. If you go in there with your smaller 2.0l quench area you may need to retard your timing more to keep the det at bay. The quench area is going to affect the way the flame front is going to propagate so you want this to be right. From what I've read, people who are reworking the quench area are getting more timing out of their engines. I'll be going this route very soon. I'll keep you all posted.


Be careful what you read. Quench is a good thing. The less, the better. I think you may have confused the combustion chamber volume with the quench area. If you are referring the piston crown being changed, yes, there are methods to promote better combustion, but I'm not aware of any that Quirt has implemented in his stock replacement CP pistons.


Javier, I'd direct my questions about a $$$ engine to the people I'm paying to build it, not a forum.


S.

I'm only going on what I've read here on Nasioc, so this may be total BS. Go to this link: http://xcceleration.com/imp-gallery-heads.htm
The area that I'm talking about is the recessed area on the combustion side of the head. At the center of this area is where the spark plug would protrude into the combustion chamber. I may be calling it something that it's not. I've heard it referred to as the quench area. From what I've been told the recessed area on the 257 heads is larger than the one for the 207. I don't know if this makes much difference but I'd love to know what an experienced builder would think. Also, if somebody has a set of each they could do a volume test for us... hint hint :D

I'm only going on what I've read here on Nasioc, so this may be total BS.

Very likely. ;)



I don't know if this makes much difference but I'd love to know what an experienced builder would think. :D


Now you know.... ;)


Also, if somebody has a set of each they could do a volume test for us... hint hint :D

Search. Search. Sponaugle provided this info for us a long time ago:

EJ205 ~49ccs
EJ257 ~55ccs

S.

I'm only going on what I've read here on Nasioc, so this may be total BS. Go to this link: http://xcceleration.com/imp-gallery-heads.htm
The area that I'm talking about is the recessed area on the combustion side of the head. At the center of this area is where the spark plug would protrude into the combustion chamber. I may be calling it something that it's not. I've heard it referred to as the quench area. From what I've been told the recessed area on the 257 heads is larger than the one for the 207. I don't know if this makes much difference but I'd love to know what an experienced builder would think. Also, if somebody has a set of each they could do a volume test for us... hint hint :D




That's not quench area. The area commonly referred to as quench is located at the flat spots in the combustion chamber. For quench to work properly you need very tight clearances between the top of the piston and the bottom of the head. You won’t get that out of the area around the sparkplug.

I brought mine up to 8200 and the sz49 was still pulling. There was 0 falloff of power up there, it literally bounced into the limiter over and over. Definately rev that thing until it's falling off. If you dyno it, I'd stop revving after it has lost 25-30whp from peak....that's about where you're done going fast.

Guys!

Changing the heads on stock helps with many area, especially making power.

The problem is that the EJ257 was design around a turbo to work with its rev range + power range.

The EJ207 was design around a turbo to utilise its high rev range, even up to 9K rpm.

Because you are using a new head now, you will need to use a new Turbo that will continue to make power in that range. Eg, EJ5-40T, GT30R and so forth + tuning to allow that and a EcuTek reflash.

Steve has a plenty good turbo for high RPM useage...could be bigger....but definately will make power upstairs.

Steve has a plenty good turbo for high RPM useage...could be bigger....but definately will make power upstairs.
You don't even know what it is anymore! But yes, you're right. It could be bigger but it will make power up top...
It's a custom made turbo using a gt30-15 chra with an avo .84 turbine housing.

As far as asking crawford, all they told me was they have a S3L that they run happily at 7200rpm. I asked about revving higher and they said "I guess you could..."

I was just looking for something more definitive than that. It seems like there are people out there doing it with success.

so it IS safe to have a 257 block and my ver8 heads revving to 8000 ? day in and day out, just like the 2.0L could stock ?

im worried abot 8.7:1 compression ratio when using 2.5 block and jdm heads. But u figure the honda guys use it(9.0:1) and love it. Will my power on pump really be that limited. Let me put it this way.

2.0 block, ej207 longblock with 8.0:1 compression
vs
2.5 block, ej207 heads with 8.7:1 compression. Using same turbo and other variables, which would make more on pump ?

What you have to really find out if the crank and con rods can handle it. For the head. The head can.

The 2.5 will make more hp at high compression lower in the rev range than the 2.0 @ the same range. But Clarke and quirt can chip in here if there are on the thread.

You should be okay in terms of compression. You'll want to retard timing a little more than with the full 257 longblock. Remember there are also a ton of Evo's out there running 9:1 compression on big turbo setups so you should be fine. Make sure you have at least one step colder plugs and don't go too high with the boost or the timing.
-Hill

You should be okay in terms of compression. You'll want to retard timing a little more than with the full 257 longblock. Remember there are also a ton of Evo's out there running 9:1 compression on big turbo setups so you should be fine. Make sure you have at least one step colder plugs and don't go too high with the boost or the timing.
-Hill

Eh, the 4g is a different motor. Just because 9:1 is ok on the evo, does not mean it is going to be as good on the subaru.. That said i wish my compression was a tad lower, trying to make any sort of power on 91 is almost impossable.

Agreed, the heads flow a little better, but you'll still be able to run the ver 7 heads with out a problem. All I was trying to say is that 9:1 really isn't that high compression. JDM heads on the 257 bottm end has been done may times before and you won't be testing anything new. Just make sure you're starting with a conservative timing map and you'll be fine. Also you could get the thicker 74mm Cometic head gaskets to drop the compression back a little if you're worried about it.
Evos have a different motor than the Subaru????? Who would have thought... :lol:

74 mm DAMN!!! that's like 3 or 4 inches. that's some heads gasket! make a 4 liter, 2:1 compression motor :D

I may have been mistaken about the size of the gasket. That's just what Gruppe put on my invoice. When it comes in i'll measure it and let you know.
-Hill

bump so i can follow further discussion...