MAG58's DOHC L28 Build Log

[Mack]

there was no animosity in my post either. The way Tony worded his post, it seemed as though he was inferring that he had already considered this possibility and new it would fit, but chose not to share this information with anyone else. But now that he has clarified that he had considered it, but never actually checked it out, the situation has been rectified.

 

THe KA head option was appealing because most (almost all) of the coolant passages and oil passages line up.

[PanzerAce]

I'm interested in this as well. While I would love to have a 9 or 10k sustainable rpm motor, I don't have that kind of money. However, if something like this can be done with just a machine shop access, that really interests me.

[Daeron]

It goes without saying that there is an undercurrent of tension regarding the entire concept of finding a DOHC/crossflow head for an L6; causes include the extreme rarity of (and accompanying disinformation regarding) the two existing "non-standard" heads for the engine (LY and OS-G), the misinformation regarding the original connection between the L6 and its Mercedes "ancestors;" and the confusion regarding Brian's franKAstein head are three decent causes to point at.

 

The only animosity/correction that was made, was regarding the statement that was made that (when blown out of proportion for purposes of illustration; I haven't even gone back to re-check who originally made the comment b/c it doesn't matter) implied that the ENTIRE Z-CAR COMMUNITY had determined that NO other existing DOHC I-6 head would fit on the Z motor.

 

Just a slip of the tongue. (keyboard)

 

Now, can we go back to playing half-breed Axis Power Plants?!?!?!?! Its SUPER fun!!!

[RTz]

Enough bickering already. You guy's are mucking up a perfectly good example of hybridizing. It makes no difference weather you agree or disagree. Let the man build his monster in peace, and share his experience so WE can learn from it. That's the purpose of this forum, in case you've forgotten.

 

Consider this your warning... If the posts are not constructive, action will be taken.

[Evan Purple240zt]

too cool man, did you have any luck getting ahold of jim about that cracked RB head?

 

Going to be watching this, been a long time since anything like this interested me.

 

Evan

[MAG58]

I'm talking to him now, I'm going to see if I can get it one weekend that I have enough time to trek up to Chicago, though work is burying me right now.

 

These are the best pics I can get of the M104 ports intake and exhaust, I really haven't had too much time to work further as doing body work for a customer is occupying 30 of the 24 hours in a day...

 

 

Here are some pics of the Intake port, from the CC side and from the intake Side, they have NOT been ported what so ever, the only thing that's been done is I've hit it lightly with a wire brush to take the carbon deposits off.

 

This is from the intake port, sorry about the blur, It's been overcast and lighting has been horrible.

 

And again from the CC

 

As for the exhaust port:

 

Also from the CC-- An interesting note here, the two dark areas behind the valve guides appear to be cast in balance tubes? they only go from one side of the port above the valve to the other side and I cannot see any other transition they make. Pushing fluid through it only shows that it does indeed come out the other side. Anyone care to weigh in on these? I've never seen them before.

 

On a descriptive note, I've been very impressed with the typical "German Engineering" that this head displays. It has VERY stiff conical valve springs and what appears to be case hardened retainers. All the valve stems appear to be micro-polished before they were put in (even at the undercut areas that the vavle guide does not contact) and the fit and finish has been far above what I'm used to seeing on our beloved L's or most American engines.

 

A valve/spring/retainer from the Exhaust side:

 

I'm going to be trying to document findings like this carefully so even if nobody dares to attempt this on their own, I want this to be informative to those interested on swaps like this...

 

Bob

 

PS: for those of you that are looking for a Head with the exhaust on the opposite Side, the M120 V12 is literally two of these engines grafted together on a common alloy V12 block, all ports bolt up the same and the exhaust and intake flanges are even equal. As far as SOHC goes if you're inquisitive about a single, two valve style head, the M103 is the ancestor to this engine (much like the RB30E and various DE conversions in relation to one another) and maintains the same bolt spacing and bore spacing but in a SOHC pattern. This engine has a dizzy drive off the front of the camshaft and maintains a larger following due to it's more economical nature and it's time in service. These heads are a dime a dozen around here and can be picked up for cheap.

[FlatBlack]

Bob, did you get a weight on the head [to compare it with the P79]? I was wondering how heavy it is, it looks BIG.

Edited July 16, 2009 by RTz

[RTz]

Well, that's two doses of infractions for those that can't/won't read/comprehend.

 

One more time. If you have something USEFUL/HELPFUL to contribute, please do. Otherwise zip it.

[dr_hunt]

I'm talking to him now, I'm going to see if I can get it one weekend that I have enough time to trek up to Chicago, though work is burying me right now.

 

These are the best pics I can get of the M104 ports intake and exhaust, I really haven't had too much time to work further as doing body work for a customer is occupying 30 of the 24 hours in a day...

 

 

Here are some pics of the Intake port, from the CC side and from the intake Side, they have NOT been ported what so ever, the only thing that's been done is I've hit it lightly with a wire brush to take the carbon deposits off.

 

This is from the intake port, sorry about the blur, It's been overcast and lighting has been horrible.

 

And again from the CC

 

As for the exhaust port:

 

Also from the CC-- An interesting note here, the two dark areas behind the valve guides appear to be cast in balance tubes? they only go from one side of the port above the valve to the other side and I cannot see any other transition they make. Pushing fluid through it only shows that it does indeed come out the other side. Anyone care to weigh in on these? I've never seen them before.

 

On a descriptive note, I've been very impressed with the typical "German Engineering" that this head displays. It has VERY stiff conical valve springs and what appears to be case hardened retainers. All the valve stems appear to be micro-polished before they were put in (even at the undercut areas that the vavle guide does not contact) and the fit and finish has been far above what I'm used to seeing on our beloved L's or most American engines.

 

A valve/spring/retainer from the Exhaust side:

 

I'm going to be trying to document findings like this carefully so even if nobody dares to attempt this on their own, I want this to be informative to those interested on swaps like this...

 

Bob

 

PS: for those of you that are looking for a Head with the exhaust on the opposite Side, the M120 V12 is literally two of these engines grafted together on a common alloy V12 block, all ports bolt up the same and the exhaust and intake flanges are even equal. As far as SOHC goes if you're inquisitive about a single, two valve style head, the M103 is the ancestor to this engine (much like the RB30E and various DE conversions in relation to one another) and maintains the same bolt spacing and bore spacing but in a SOHC pattern. This engine has a dizzy drive off the front of the camshaft and maintains a larger following due to it's more economical nature and it's time in service. These heads are a dime a dozen around here and can be picked up for cheap.

 

That is a tulip shaped valve, should be better flow than the design used on the l28. Ports don't look all that big but it would be interesting to see how it flows and I'm curious to see the end result of your endeavors.

[ModernS30]

I am super interested in this build. It is inspiring to see people trying to figure out things like this. By any chance what part of Indiana do you live in? There are a TON of race shops around here, but most of them deal with open wheel cars.

[MAG58]

I live in the Middle of Nowhere, haha, I'm about an hour between both Lousiville and Evansville, the two river cities, and then about 3 hrs south of Indy. There's pretty much nothing where I live, but ERL performance is about an hour away by Louisville, and there are a ton of race shops in Indy.

 

As for the valves, the ports aren't giant no, but they do pretty well compared to the L series, I'm still trying to find a reputable shop around here to flow them, but for what I'm building it to be I think they'll do just fine, nice straight ports with no funny casting quirks to get around, and there is some good meat left in the event I wanna port them.

[Careless]

I think the coolest thing is that you can go 2JZ style or RB26 style by choosing which head you want from the V12 version.

 

That in itself is pretty awesome! I think having the exhaust on the passenger side might free up some space from the booster and the steering column and allow a lot more tube to fit in there!

[NZeder]

That in itself is pretty awesome! I think having the exhaust on the passenger side might free up some space from the booster and the steering column and allow a lot more tube to fit in there!

That does also depend on which side the passenger sites us with the RHD would like the RB26 Style. However the engine would need to be leaned over for the RB26 style which would mean getting a Z20/Z42 bellhousing for the L6 box or would a RB bellhousing mount up ok - might have to keep an eye on this project the thing I like about this is L6 bottom end and chain drive.

 

I have gone RB conversion for the DOHC look (as I know the L6 in NA form will produce more than enough flow and power for my purposes) so this is one of the ways I can afford a Z432 theme/concept but using a modern Nissan motor. To have a chain driven L6 with a DOHC I like the idea and I hope this project continues to shed some new light and interesting results.

 

Hybridz is the name of the site and Hybridizing the name of game and it is game on with this concept.

 

Those ports look large so - would the head be too large for NA setups? I think a L28 bottom end would need to increase in cc to match a head with ports like that (no idea really not a mechanic/cylinder head guy)

 

I found a website the other night with pics of these engines (lost the link will have to check again) but they showed the cranks for these engine - very nice fully counter weighted - anybody know the specs on these and if one could be made to fit a L6 bottom end

[ModernS30]

I was thinking, has anybody ever thought about making a casting mold out of like the KA segments design. that way, you mold the segments, and end up with a solid cast able mold. this way you could just have a direct replacement, I would see it taking a bit of time, possibly TIG welding the segments together, and smoothing out the welds. Then somebody could bulk cast them, and sell them to people. I'm not sure if this is even possible, but if it is, I think with some work it could be made possible.

[Xnke]

The problem with that is that the cam drive is the hard part of all of these swaps. A cast FranKAenstein head would still have the issues with cam drive that the segmented version would, so you are not really gaining anything.

 

Mag58, have you thought about driving just one cam by chain, and having the other cam run by a gearset? This might allow for the L series cam sprocket to fit on the most convenient cam, and then using a gear setup similar to some other DOHC heads I've seen.

[MAG58]

Well the lower crank sprocket is actually within a few thousands between the M104 and the L28 crank snout, so I'm tossing around either milling the snout and using M104 crank snout dia to use the damper and the crank sprocket off of the M104 or just mill the crank sprocket for the L series. I'm leaning towards the former to maintain the strength of the crank sprocket and I'd only need to get the oil pump gear to run the oil pump, since it's going to end up COP or EDIS with MS timing wont be a problem. I'm currently tossing these ideas around with a local engine builder to see which will be best and this should solve my cam problems.

 

 

Either way I look at it, the bottom end is in machine shop jail for a while, after that progress should quicken up.

 

While I'm sitting around though I'm going to try to investigate the viability of the entire M104/M111 6sp assembly into a Z since it really is such a well designed motor, give me something to do while the professionals do their work...

[Xnke]

I'd go for machining the sprocket, as using the Mercedes damper is not going to necessarily damp the Nissan harmonics...if it's only a few thousandths, then machine the sprocket.

 

Solves the oil pump drive problem too, easy.

[ModernS30]

My dad said if you want it done right a good some in Indy would be M & M Automotive, just a word of advice, I was tellin him about this.

[MAG58]

Sounds good, I will def. be checking them out then, much tanks.

 

For those of you anxious for a timing chain fix, the head got thrown on the ol' mock up block one more time, and I used the stock Datsun chain (Just to see where I'd land) put it around the cam sprockets and laid the Merc crank sprocket at the bottom. Lookin' at it, I couldn't find the stock Datsun curved chain guide, but that one should get kept (as marked by super high-tech finger technique) , right in the stock location, same with the chain tensioner, and I'll put the Mercedes chain guide on the right side (as pictured)

Note: the chain's a little short, the crank sprocket is sitting where the chain tensioner is supposed to be... All I have to do is find the right chain length, all Mercedes have the same size chain as the Datsun, just have to find one that fits.

[Xnke]

Looking good, might try the double row chain from a Z24 or L20B motor, or get a chain breaker/maker. I believe you can get individual links for Mercedes motors.

 

Anyway, getting the sprocket cut shouldn't be a big deal, just go to any machine shop, automotive or non, and have it bored to X diameter. if it's a non-automotive shop, DON'T tell them it's for a car, and chances are it'll get done for a lot less.

 

psssst...look at the Kameari chain tensioner for the L-series. Chances are you won't need the curved Datsun guide anymore, or the chain tensioner, but it's expensive. But I bet it would work.