legacycentral bbs

I have read on this board on more than one occasion that the two set of heads on our cars are identical except for the cam profiles. Yesterday, I empirically verified that at least when comparing an 1990 NA EJ22 with a 1992 EJ22T, the heads are NOT the same.

For starters, the intake valves on the NA engine are bigger than the ones of the turbo. I measured them and the turbo are 1 3/16" while the NA ones are 1 1/4" Furthermore the turbo ones are marked IN1 while the NA ones are marked IN2. The exhaust valves are identical at 1 3/32"

As is already known, the valve covers are different, with an oil return bung on them. But what I hadn't noticed before is that the passenger side turbo head has a coolant return line sticking out of the side of the head. This is not present on the NA head.

Next, I looked at the faces of the heads and compared them and the gaskets. The NA head has more coolant passages in the head on the intake side.

You can see from my old turbo head picture what I am talking about. On the right there are three, but on the left there are only two. On the NA there are three slightly smaller passages on the intake side.

Sorry, i don't have any new pics to help show all this. I am gonna try and borrow a camera in the next day or two and give more blow by blow of the differences I have found.

When I disassmbled the heads, the rockers were identical between the two, with identical markings on them. And as is known, the cams are a very different grind. I don't know how to measure the lobes for lift and duration but can describe what I saw. The NA cams have the intake and exhaust lobes about 180 degrees apart on the rotation. The turbo cam has them more like 40 degrees apart. There is a huge difference in the grind between the two.

The manifolds are definitely identical, as are intake and exhaust port sizes on the heads themselves.

Lastly, the turbo head is cross hatched just like the EJ22T blocks are. This makes me wonder if it is made using the medium-pressure casting technique Xephyr talks about being used for the turbo block itself. The NA head doesn't have the cross hatches, and in addition to not having the coolant bung(that appears to be drilled in and added after casting, while the NA heads don't even have a spot where this is possible.) there are a few other subtle differences in braces and what-not that make me sure the heads are different cores. I will post pics of differences as soon as I can.

Lastly, just a side not about the block itself. Here is a picture of the new EJ257 STi block.
You will note how skinny the braces are on the crankshaft axis. The 'semi-closed" braces on the sides are much much thicker. I was quite surprised, but the NA EJ22 deck had much larger braces on the crankshaft axis than the EJ257. They were about as thick as the side braces on the EJ257! Even though it is still an open deck engine, this makes me want to further pursue my frankensubby project as a turbo build. I have been talking about these old NA blocks being stronger than people give them credit for, and we all know the USDM EJ205 blocks are open deck. Here's an EJ205, and my EJ22NA block has pretty much identical bracing to this...

Now I really need to figure out if I want to do this with some EJ25 heads and stock NA pistons OR make a truly EJ22 build and use the NA heads with turbo cams on the NAEJ22 block with EJ22T pistons. If someone has a set of used, but functioning EJ22T pistons they wanna donate to the cause or sell super cheap, let me know and it will make up my mind. I can get a new set from Quirt Crawford for $100, so used ones better be real cheap.

More to come...

you're awesome. I belive rod or someone had a build going with 12psi on an na ej22 before he blew it. I forget what he was doing though for control. So that's saying omething about the na ej22's

yeah,
I know of a number of totally stock NA EJ22's running 10-12 psi on DIY or FAT's turbo kits. But I am thinking that if I drop the CR to mid 8's I can strap on a decent sized turbo and run more in the 15-18psi ball park.

Do you know what he blew on his engine? My guess is the headgasket unless he didn't have enough fuel flowing and then he could have really blew it...

too much timing advance but I dont remember what actually went.

The 1991 FSM lists intake valve size as the same for turbo and N/A.

Cam profiles are as listed:

INTAKE
N/A: open - 4 deg BTC
closed - 52 deg ABC

Turbo: open - 6 deg BTC
closed - 52 deg ABC

EXHAUST
N/A: open - 48 deg BBC
closed - 12 deg ATC

Turbo: open - 42 deg BBC
closed - 10 deg ATC

It doesn't sound like much by the specs, but I never visually compared. It surprises me that something seemingly able to be better compromised (like single cooling passage design) wouldn't be for the sake of saving expense of two head-type mfg. I stand corrected and the manual may be wrong if you physically measured the intake valves as different sizes. I never had the chance to compare side by side the two heads. I wonder if you could still use the N/A heads on the turbo provided the machining process was done for the turbo lines. The bigger intake valves wouldn't hurt.

It's great you could actually get them side by side to compare.

Steve

didnt someone post that the inakte valves weere made smaller to increase torque? or something similar

I think the fsm info on the cams is incorrect. How incorrect I don't know.

Rod was the one running the n/a EJ22 with the forced induction turbo kit, garrat turbo & alcohol injection. I recently talked with him, and it wasn't the motor that blew. They took it apart, it was fine. It was the turbo that had issues.

Granted I still think you would want to control timing, but if you got a good piggy back or even stand alone, I'm sure you could make a n/a EJ22 turbo'd and have it be reliable.

Very good info. I think some of us go gung-ho over the EJ22T so much that we forget how good the n/a EJ22 really is.

Either cam profiles make little difference or there can't be much between them as my power loss from going 9.5 CR to 8.0 is not as noticeable as I thought it would be. The only thing between them is a drag race from a stand still, but power beyond that feels nearly the same. I don't think the cams would be better optimized for a lower compression N/A application.

Steve

Legacy777 wrote:I think the fsm info on the cams is incorrect. How incorrect I don't know.

Rod was the one running the n/a EJ22 with the forced induction turbo kit, garrat turbo & alcohol injection. I recently talked with him, and it wasn't the motor that blew. They took it apart, it was fine. It was the turbo that had issues.

Granted I still think you would want to control timing, but if you got a good piggy back or even stand alone, I'm sure you could make a n/a EJ22 turbo'd and have it be reliable.

only the turbo? wow, this is good info to know

Yup,

They tore down the motor, and it was fine.

Steve,
Both the FSM and I might be right since my NA heads are 1990's. It may be the case that with the introduction of the turbo in '91, they did in fact switch to the same cores or at least same valve size. It would be nice if a member had a set of '91-94 NA heads they could measure. Wait a minute, I can call LegacyMax and have him check for me. He works for CCR building EJ22's all day long...

As for that coolant line? I don't know that it is 100% required. After all, neither the SOHC or DOHC EJ25 heads have them, and there are plenty of those heads strapped to high powered EJ22T blocks with no issues.

I am going to have to look into the cam thing a bit more. Thanks for posting those specs. It has been suggested that the extra duration of the NA cam may actually help on a higher powered turbo build.

The other thing that has occured to me is that those differences in holes that I found may not matter a whole lot. I am pretty sure those holes are the coolant drains out of the heads, So as long as they don't pose a restriction.

One last thing that I recently mentioned to Thawa, but forgot to make public is head flow characteristics.
http://www.mrtrally.com.au/performance/
http://www.cobbtuning.com/tech/sohc/page2.html
Many around here are familiar with this Cobb article where they bench flowed the EJ22T head. But did you know that our EJ22T heads outflow the EJ205 heads found on the USDM WRX's? Look at that MRT link and hit the tech link at the very bottom. According to those numbers, our heads flow 25-30% better than the WRX. OF course, this wouldn't be the case if looking at older EJ20K heads or STi heads. v7 spec C heads flow a whopping 260cfm intake and 195cfm exhaust on 0.400" lift!!! So, to my reckoning it is a waste of money to buy USDM WRX heads for use on the EJ22. Even after porting, they still don't flow as well...

oh btw, I had meant to tell you this link is what you were looking for: http://www.mrtrally.com.au/performance/techtips.htm

I should have valve measurements for the USDM EJ205 heads pretty shortly. We didn't manage to get the heads off before dark, so we called it a night. But the ports themselves are a fair bit larger than the EJ22 ones. The inlet ports are 2 1/16" IIRC, that is 3/16" larger than the 22's. So, if those heads do in fact flow less than our, I expect to find some pretty small valves once we pop the heads off...

Ok,
I got the EJ205 heads off the engine and I don't buy MRT's numbers anymore. They must have used a very different test set up (like depth) because the ports and the valves are all significantly larger than the EJ22T ones...