I need some old-school engine building expertise...

[Kostamojen]

I'm basically trying to get as much assistance as possible regarding the motor i'm putting together for my FF-1 project. I'm not getting much help in the main thread, so I'm going for the actual engine information section for this.

 

Anyway, here is a short brief for the un-initiated:

 

Its an old EA motor, EA63 to be exact (1400, 1.4l, 1361cc).

The original motor was an EA61.

The shortblock is a NEW 1.4l dry-sleeve (as opposed to wet-sleeve which is what most 1.4l's are, finding a dry-sleeve 1400 is HARD to do).

The cylinder heads are dual-port (front/rear port) 1400 heads, which I MUST use due to engine mount/crossmember location (cant use single-port heads).

 

Now, for the serious information...

 

I'm trying to use a VERY rare Weber manifold on the engine, as seen here:

 

 

The big issue is the Weber manifold is 4mm shorter than the stock manifold!

 

This is because that manifold is designed for a JDM-only "sport" motor (1300G) that had a shorter shortblock. That motor I can't find, and don't want to use anyway due to the fact it is a WET-SLEEVE motor (more headgasket failures, harder to maintain, HARD to rebuild). This manifold will let me use a very nice dual-barrel carb setup, and I spent a LOT of money on it so i'd like to use it

 

Now the problem:

 

As you can see in the picture, the manifold DOES bolt to the engine and line up perfectly with NO HEADGASKETS installed. I've done all the measurements and figured it is exactly 2mm each cylinder head that needs to be shorter.

 

I've started talking to engine machine shops about this along with various old-school Subaru guys and i'm getting mixed information/opinions.

 

My goal with this engine is NOT a pure-race engine, but a quality, reliable street driven engine.

 

Known Options:

Shaving the heads -

In order to run the manifold, the easiest (and cheapest) option is to shave the head 2mm each side. This will increase the compression ratio of course, however i've been told anywhere from 10.0:1 to 15.0:1 (stock compression ratio is iether 8.5:1 or 9.0:1, depending on the year of the 1400, in this case i'm not sure but i'm guessing 9.0:1). I'm fine with something around 10.0:1 as long as the headgaskets will hold up and i'm fine running and tuning it to premium gas.

 

Custom thin headgasket -

I've done some homework into custom headgaskets that are thinner (the OEM and aftermarket headgaskets for this motor are 2mm thick) like Cometic and Copper gaskets. From what i've read, MLS (multi-layer steel) headgaskets are best, but Cometic won't make just one set of custom headgaskets.

Copper gaskets i'm getting mixed messages about, with some saying they are a PITA and should only be used on pure-race engines, while others have no issues with them.

Either way, i'd still have to shave whatever the thinkness the gaskets are from the cylinder head to fit the manifold.

 

Pistons -

I've been thinking that somehow modifying the piston (shaving?) to solve the compression ratio issue with shaving the cylinder heads. Custom pistons are expensive, so are modifying normal ones something that actually occurs?

 

Other potential solutions -

I've had people say to modify the intake manifold or put some kind of spacer on there. Thats more difficult that one would think because not only does air travel down the manifold but coolant as well...

Any other ideas would be helpful.

 

 

My only other solution is to run the stock manifold with a 32/36 weber carb which is what most other people run on old EA motors, which isn't that interesting of an option (plus i'd buy a new one of those with the adapter and such, which runs around $400 anyway. Shaving the heads and using the weber manifold with the carb I have with that will cost less than that!)

 

Note: I have not calculated the cc of the compression chamber and have never done something like that before, but it has been mentioned to me.

 

P.S. If you have any other general questions about what i'm doing, or need more photos of something specific, just say so...

[Kostamojen]

BTW, here is the main thread for reference:

 

http://www.ultimatesubaru.org/forum/showthread.php?t=80021

[Numbchux]

for starters, I'm no expert. but I've done some CR calculating....

 

I think you are going to need to start with some math, and finding out exactly what ratios these combinations would yield. I've heard of people just filling the chamber with oil and measuring it. as far as I know, shaving the heads and using thinner gaskets will have the same (or very similar) effect on the compression.

 

I think the best option, would be shaving the heads, using stock gaskets, and then using custom pistons to dial in your CR. I know there are companies that make custom pistons for the EJs (my buddy just got a set from CP pistons), but they make them unique to your exact bore measurements, valve reliefs, and CR. it seems that they could make them for a different motor......I dunno.

[GeneralDisorder]

The solution is actually really simple - just have someone with a mill oval out the bolt holes for the manifold.

 

Mill down the heads - but only .020" as that is about the limit. It will increase your compression ratio slightly - 2mm off each head would be an ENORMOUSE amount of material (almost .080") and would result is not only pretty serious compresison increase but also possibly requireing custom push-rods to correct the valve train.

 

I say take 1/3 of the distance you need by milling the heads. Take the other 2/3 out of the manifold bolt holes and then port match the intake to the heads. Should work just fine - there is a lot more material on the manifold and head intake ports to work with without disturbing your valve train or compression ratios. Also your exhaust manifold will still bolt up.

 

GD

[Kostamojen]

Just doing the manifold bolt holes doesn't solve the problem of the intake and coolant passages no longer lining up.

[baccaruda]

You should be able to port match them too... got a Dremel tool?

[Don_Quixpunch]

Just spitballing here. I could be completely off base, but if you're not interested in the machining idea the GD shared, I've read about people bumping the compression of their EA81s by swapping in EA71 pistons. If your engine has the same bore(92 mm?), could you go the other way and put EA81 pistons in it to drop the compression and make up for some or all of the CR gain from milling the heads and/or crankcase?

 

Or, if you have a different bore size, perhaps you could share your bore size and the height of your pistons so that other board members looking to kill some time could help you search for a piston from another engine that would fit the bill.

[GeneralDisorder]

Just doing the manifold bolt holes doesn't solve the problem of the intake and coolant passages no longer lining up.

 

The offset will be very small - only slightly more than 1mm. Easily port matched with a die grinder and a carbide burr. Not a problem at all.

 

GD

[rxleone]

I probably sound like a retard by saying this, and I know that weber manifold is one-of-a-kind rare, but is it possible to slice 4mm out of the manifold on one side and have it re-welded? Or is it too valuable?

[subaruguru]

The intake is CAST aluminum with the water and intake passages in the same unit you can weld the outside and it would be back in one peice BUT you have no way to weld the inside wall between the water and air passage.

 

Rob.

[Kostamojen]

The offset will be very small - only slightly more than 1mm. Easily port matched with a die grinder and a carbide burr. Not a problem at all.

 

GD

Its more than that for the offset, the manifolds are not perfectly horizontal across the block, they are at an angle which means to port match it you have to triangulate the location. Thats why I couldn't tell how much shorter it needed to be until I did headgasket measurements and such. You cant tell just by lining up the manifolds to each other exactly how you need to change it.

 

Its just a bad idea any way you slice it, when you start trying to match the ports you loose gasket matching and end up with bad flow in the chambers from the awkward lips and such.

 

Right now i'm thinking I need to go back to my original plan... Just put the 1400 together with the stock manifold and build a motor later using the 1600 shortblock I have, since this is going to be so much work to do properly.

[GeneralDisorder]

You are making it a bigger deal than it is - if you shave the heads that's 1/3 of the distance you need. The rest is split in half between two ports - that's not much at all.

 

The ports don't even need to line up that well - the stock manifold's don't. If this were an indy car engine then maybe we would be concerned. It's not a swiss watch. There's going to be things in the intake tract that disrupt laminar flow - that's just the way it is. One more little blip on the side of the intake port isn't going to matter.

 

GD

[Kostamojen]

The stock manifold doesn't match very well, but right now the gasket, webber manifold and heads all match perfectly.

[carfreak85]

Having done some very serious staring and poking with finger analyzing of EA81 heads during the course of one of my power mechanics (engine design) classes, I can tell you with certainty that the heads are keeping you from making power.

 

The uneven port overlap will indeed hurt overall airflow, but just look at the flow path once it gets past there. IIRC, the EA81 head has 12 turns from intake gasket to exhaust gasket. Ideally, there would be less than five.

 

The intake side of the equation is far more important than the exhaust. You care more about getting air in than getting it out and, that being said, I would try using the heads the Weber manifold wants. Even if it is single-port and the resulting exhaust looks terribly restrictive, it is less of a compromise, power wise, than fudging on the intake port. Plus it will aleaviate your head gasket/milling problems.

 

I would recommend porting the heads and matching the ports on the manifold. The engine makes so little power that you might as well do what you can to ease the engine's job of drawing the charge into the cylinder. You can do it at home, just be slow, careful and patient. The gaskets will be the template, try to blend the cut as far down the port on both sides as you can.

 

You mentioned the cross-member gets in the way of a single-port exhaust. How 'in the way' is it exactly?

[Kostamojen]

Having done some very serious staring and poking with finger analyzing of EA81 heads during the course of one of my power mechanics (engine design) classes, I can tell you with certainty that the heads are keeping you from making power.

 

The uneven port overlap will indeed hurt overall airflow, but just look at the flow path once it gets past there. IIRC, the EA81 head has 12 turns from intake gasket to exhaust gasket. Ideally, there would be less than five.

 

The intake side of the equation is far more important than the exhaust. You care more about getting air in than getting it out and, that being said, I would try using the heads the Weber manifold wants. Even if it is single-port and the resulting exhaust looks terribly restrictive, it is less of a compromise, power wise, than fudging on the intake port. Plus it will aleaviate your head gasket/milling problems.

 

I would recommend porting the heads and matching the ports on the manifold. The engine makes so little power that you might as well do what you can to ease the engine's job of drawing the charge into the cylinder. You can do it at home, just be slow, careful and patient. The gaskets will be the template, try to blend the cut as far down the port on both sides as you can.

 

You mentioned the cross-member gets in the way of a single-port exhaust. How 'in the way' is it exactly?

I'm not sure how to reply to this, I think we've gone off on a tangent here :-p

 

These are NOT single port heads. Look again at the first pics. And the intake valves are actually on the INSIDE instead of the OUTSIDE which means they are almost perfectly in line with the manifold port, which means less turns. Combined with the front/rear exhaust ports, these are the best flowing stock EA heads bar none.

 

As for port matching, as I said, right now the gasket, intake port of the head and the weber manifold all match PERFECTLY. There is no more need for porting unless I want to use custom gaskets or want to run a higher-powered motor.

 

And yes, the engine mounts are exactly where the single-port exahust ports are, there is about 1/2" clearance, not even enough for the exhaust studs to fit. And as stated, there is no reason to use a crappier single port head anyway...

 

My issues are not with intake porting and such, its with compression and manifold/block/etc. length.

[carfreak85]

You want to use head gaskets correct? I was under the assumption that the parts all worked perfectly w/o gaskets.

 

Thus, using gaskets (kind of a necessity, don't ya think?) would throw the manifold's alignment out of wack, necessitating the port work.

 

In that case, I would oval out the bolt holes on the manifold and just slap it on with OEM gaskets. Maybe deck the heads a little.

 

Using the dual-port heads will make up the lack of a 100% matched gasket surface. I would still suggest some blending of the ports, but you made it sound really tough, so I guess it's up to how you want to spend your time/$.

[Don_Quixpunch]

Just for giggles, I looked up the EA63 on Wikipedia which says your bores are 85 mm. So I Googled 85 mm pistons and some of the engines using that bore are Honda B series, Hyabusa, Mazda MX6, Lotus, Mitsubishi Lancer Evo, VW VR6, Rotax 738 CC, BMW 1800, and so on.

 

I don't know your wrist pin diameter or the height of the EA63 pistons, so I can't narrow it down any further, but I'm willing to bet that you could find a piston that either works or could be easily modified to work.

[Kostamojen]

Just for giggles, I looked up the EA63 on Wikipedia which says your bores are 85 mm. So I Googled 85 mm pistons and some of the engines using that bore are Honda B series, Hyabusa, Mazda MX6, Lotus, Mitsubishi Lancer Evo, VW VR6, Rotax 738 CC, BMW 1800, and so on.

 

I don't know your wrist pin diameter or the height of the EA63 pistons, so I can't narrow it down any further, but I'm willing to bet that you could find a piston that either works or could be easily modified to work.

Now thats some awesome information, thanks. I'll have to pull out one of the pistions from box of parts from the other EA63 I disassembled and check.

[Kostamojen]

Here is a photo of the EA63 piston, the top is flat (got this from ebay):

For reference, These stats were taken from a EA71 piston via ebay:

Comp Height 31.5mm

 

Overall Length 71mm

 

Comp Ring 1 @ 1.2mm 1 @ 1.5mm

 

Oil Control Ring 1 @ 4mm

 

Pin Diameter 21mm

 

Clearance (Minimum) .0006"

 

 

I'm fairly certain the pin diameter is the same, the rest i'll have to double check.

[Don_Quixpunch]

As I look at the Honda pistons, they're made for a variety of compression ratios. I'm going to keep looking for the Honda wrist pin size. Because you're not looking at using them in a Honda, you can't rely on them actually giving you the stated compression ratio. The height of your current pistons is needed in order to find new pistons that are around 2 mm shorter.

[Don_Quixpunch]

So one set of Honda B20 pistons I found are 85 mm, and have a 21 mm wrist pin. Your wrist pins are 22 mm according to Wikipedia. If you could find a set at the right height, they would need to be bored out and have the retention ring grooves cut deeper by a machine shop. It looks like the pin end of the Honda connecting rods is 23.75 MM, I'm drawing a blank on the EA63 pin end width. I know there needs to be side clearance, but I don't know exactly how much.

 

You will probably need to have a rod and piston from each engine in hand to really be sure they can interchange.

 

I'm pretty good at finding things out online, and I think your FF is incredibly cool. I'm not close enough to help hands on, but I can help look stuff up.

[Kostamojen]

The height of your current pistons is needed in order to find new pistons that are around 2 mm shorter.

I think the piston wouldn't have to be 2mm shorter. When shaving the 2mm from the head, the amount of cc's taken out are not the diameter of the piston, but actually the size of the valve relief area. I need to find out exactly how much that is via cc measurement to see exactly how much lower the piston would need to be.

[Kostamojen]

Ok, got one of the 1400 pistons from the old engine for measuring:

 

Comp height - 31.5mm (from middle of piston pin to top of the piston)

 

Piston pin - 21mm

 

Piston diameter - 85mm

 

Overall height - 66.5mm

 

Oil ring - 4mm

[Kostamojen]

BTW, JE can make custom pistons:

 

http://www.jepistons.com/TechCorner/SCP_Drawings.aspx

 

But thats expensive of course.

[Kostamojen]

This is better, these are the measurements for the stock piston: