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madkaw

L28+(maxima)47 build

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I lucked into an MN47/L28 combo that was a fresh rebuild. It's a nice combination. I had to open up the SUs all of the way to prevent it from being too lean. I've also considered researching a different needle profile to fatten up the carburetors some more.

I'm also running square port headers on the round exhausts. I haven't seen any issues thus far.

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2 hours ago, madkaw said:

Which L28- tell me more :)

LOL I forgot which block. It's probably an N42, though I know better than to swear on it.It has flat top pistons. I asked the previous owner about details. He said that aside from the head and pistons, it was just a run-of-the-mill build. All I know is that the engine pulls a hell of a lot better than the old tired engine I had in the car.

 

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Cmon Steve -is this just a teaser? I've got a thread going here about this engine combo and you just casually say you have one!!!.

Stronger than last engine? What timing are able to run? So you sure you have flat tops but in a N42 block?  Good to hear about the header, but I was pretty sure that wasn't going to be an issue. The liners should fit well inside the gasket. What octane are you running? I imagine the head hadn't been cut?    

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I wouldn't purposely mess with another Steve.

We took it easy on the timing since I still had some regular mixed in with the premium. I have just been putting in ethanol free premium since a week before my friends and I did the swap. I wasn't too worried about the details of the engine since I got an insanely good deal on it. It even had a new clutch and flywheel thrown in. 

Here's a photo of the engine when it was in the previous owner's car.

DSC02620.JPG

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So I guess you know what compression your dealing with? It will be interesting what timing you can run. I would definitely get a rich mixture going first. If you can run 35 all in I think you are doing good.   Looks like a serious set up, so I would venture it has a cam? Really no details on the engine?  

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I do want to perform a compression check on the motor. I've been busy helping a friend with his LS1 240Z. If I can remember, I'll put the car on my ramps to see if I can get the block type. I also need to check the fuel pressure and decide if I am going to change out the fuel pump.

Finally, there is some re-wiring I want to do in order to power the fuel pump while starting.

Have you planned out what fuel pump you're going to use?

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Are you going to measure flow when you're done?  At least to balance the six, maybe not actual CFM numbers.  A mismatch in flow could make tuning difficult since the ECU (CU?) assumes equal flow.  

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That would be the ideal scenario , but maybe not realistic for me. Lots of measurements and eyeballing is about the best I will do. I will be measuring combustion chambers to make sure they are equal.


Sent from my iPhone using Classic Zcar Club mobile

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I've thought that a person might be able to make a simple comparative manometer using a shop vac and clear hose in a u-shape.  Fill the hose with water and set up a Bernoulli type system to pull the water up.  Make marks and you can compare each set of ports and runners.  No numbers just seeing if they pull the same.

A good vacuum gauge might be precise enough to get some good readings also.  Or a pressure gauge on the inlet side of a blower, instead of a shop vac.  Won't show flow but would allow one to one comparisons.

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I have actually considered something like that , but never have implemented it. Now in the middle of building a new shop I'm lucky to get anything done

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Well I can actually say I’m making progress again. Wanting more power for this summer and getting my Megasquirt going has been a big motivator. The block has been sitting under plastic bags and the guts have been in Tupperware totes.

I had already sized rings so they were ready to go. I had to clean the pistons again for the third time after noticing i missed some carbon in the ring glands. I also drilled out the plugs on the block to get full access to the oil gallery. After getting that done it was time to clean again. 

Id say assembly went smoothly but had issues with oil clearances on 4&5 mains. All the caps were numbered and marked with dots( which I did neither to the best of my memory) . I put it back the same way and 4 had only .001 clearance while 5 had .003. I tried everything from deburring, filing , swapping bearing shells to improve things and nothing worked. When 4 got torqued , it made the crank noticeably harder to turn. I finally had to resort to calling my machinist for advice. He said to try swapping caps, and I did , and it worked. Crank spun freely and plastic gauge showed .002 on both. That was a big victory ! I knew this engine spun freely when I took it apart , but didn’t pay attention to the markings other than that they were marked. 

Piston pop out is .023 . Yes the block was shaved . 

Waiting on a timing kit to come in since I wasn’t happy with the Melling kit. Dam crank sprocket would even fit ?

Time to dust off the MN47 . It’s been sitting in a box for a very long time and I wasn’t even sure how much more work it needed. I considered using my E88 that’s on my L24 , but at 37cc Chambers , I think it would be too much CR, besides the fact .050 has been shaved off it and makes P2V clearance much less. 

The MN47 needs more port work around the guide area mostly, then dropping in bigger intake valves , so it will take a minute . But it will get most of my attention for a while . With block pretty much done , I can concentrate on the head . 

62CE6B16-CC04-4F0C-BD30-0D9C45EDC49A.jpeg

64F7280B-28BA-47E5-9CB3-5551D5FFDB33.jpeg

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Steve....Did you decide on a Cam yet? If you are still interested in my new Isky Stage II, I’ll let her go. I’ve got two Stage III backups, so I won’t be needing it. $195.00 .....I’ll pay shipping.

Guy

Edited by Diseazd

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What’s the rpm power band on that stage 2?

its probably too small for what I want . What are doing with all those 3’s :)

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Them 3’s are staying in Virginia....the 2 is a .480 lift 280 duration....not sure about the power band.

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More progress - finally I am satisfied with the combustion chambers and head in general , so time to measure . MN47 are said to have 39cc chambers , but I beg to differ. 41.2 cc right now with bigger valves and head surfaced at least .015. I did unshroud the chambers which I gained some there, but it wasn’t a lot.

No cam picked out yet , but I have springs. I will still probably drill and tap the coolant passages on 2-6 cylinders . The marks are there already , so I’ll just finish what Nissan started.

 

1C42E7A7-2FB3-4887-A23A-9EDF7516E642.png

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On 2/6/2018 at 12:36 PM, madkaw said:

 

 

64F7280B-28BA-47E5-9CB3-5551D5FFDB33.jpeg

That picture should make people think about some of the published Data on some of the Flat Top pin. heights. I've always contested that the OZDat engine calculator has got the pin height wrong, as it calculates the piston crown as being below the deck surface. Same as the dished pistons. That is obviously incorrect. 

Very common for FT' to stick above the block deck approx 0.021" to 0.024" .  And why you always check dimensions.... 

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I don't like that OZDAT either but for another reason, too complicated for me. LOL

I like this one,  http://www.240260280.com/legacy/techtips/calcs/engine builder/index.html

ozdat has block height at 207.85

240260280 has 207.87

Looking back at those numbers I made a mistake apparently because it seems bassackwards now???  I'm not the shiniest valve in the head.

Edited by siteunseen

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23 hours ago, Chickenman said:

That picture should make people think about some of the published Data on some of the Flat Top pin. heights. I've always contested that the OZDat engine calculator has got the pin height wrong, as it calculates the piston crown as being below the deck surface. Same as the dished pistons. That is obviously incorrect. 

Very common for FT' to stick above the block deck approx 0.021" to 0.024" .  And why you always check dimensions.... 

I didn’t make a specific statement - but I did say in this thread that the block had been shaved - .005 to be exact 

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Now the dilemma ——-

Dave Rebello called and my stroker short block is done and is shipped ! Do I finish this motor with the L28 bottom end or just go for the 3.2 with the maxima head !

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Can’t believe this thread is 4 years old. Man I’m slow. I did order a cam today for the build . Potter Racing cam! Once I have it in hand I can actually start the rest of the assembly. Need to work out lash pads once cam is here, then check PVC - hope that works out well -eek! 

Meanwhile the 3.2 block gets a bath so I can drop the crank in! 

56E5CD75-BBDE-49AD-9594-787D135658E4.jpeg

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