The first build will be just a stock bore L28.

I asked this at Hybridz, but anyone with definitive flow numbers when comparing the smaller 1.65 intake valve to the 1,72? This MN47 has the smaller valves and would love to not have to change to the bigger ones, but don't want to install a larger cam to just be negated by a 'too small valve' problem.

The Mn47 is kind of unique because it's "D" shaped intake ports that neck down to 31mm. So maybe that

might have some bearing with this question.

Messed with the MN 47 head today. It was more of experimenting on my head named "warpy", for it's .030 warpage. This is my flow bench head and

practice porting head. I also wanted to remove the liners to see

what's under there. I am curious if there is any usefulness for removing them and how much work was it.

I can say that the liners are in there pretty damn well. It took me about an hour to just get one out. I was trying to be somewhat careful as not to damage valve seat or guide or any surface. The liners leave behind a

lot of work if you are trying to make the port flow. Sharp edges and

raised areas for supporting the liner shells. I don't see myself trying

to use this head without liners, but I will try and make one port flow

without them.

I also wanted to use this head to develop a tapered sanding drum to

making porting easier. I have a FI intake in the works that has rather

larger ports -37mm- at the head, so I will need to open up a head to use

it.

Well decided, after reading lots of stuff about valve size, to upsize the intake valves to the 44mm . Opinions vary, but it seems that I'm leaving an easy 20+ hp on the table by not upsizing. Found some new old stock valves and seats on eBay for cheap and snagged them. The head is at the machinist now , so I might see it before summer is over. Should give me plenty of time to get my block together . 

Still haven't got  the cam ,but that's next. 

Thanks for the pictures.  Do you have any pictures of the exhaust with the liner removed, and no other work done?  i'm curious what it looks like.  I have an N47 with one liner loose.  I might want to play around with it too.

On 12/28/2015 at 4:40 PM, madkaw said:

(Snip)

I have a FI intake in the works that has rather larger ports -37mm- at the head, so I will need to open up a head to use it.

Hmmm... I like that Intake, Is this your own fabrication or did you buy it somewhere. If your own, are you making anymore and how much? TIA.

Richard

Richard,

this was an abandoned project that I bought off of eBay . I'm surprised in my postings on here and hybridz that no one has claimed it. It was a very nice start to a custom intake. The runners on the cannon intake were tapered already from 44mm at the plenum and 37 at the head. All the welding you see was also already done and seems to be done very well. The original builder welded a piece of channel to the intake, and I have been finishing the round "topper " using 4" pipe.

the intake also came with 14mm weld on injector bungs which need to be placed.

The "nose " was fun to fabricate. In actuality I prefer doing this type of fab work more than any other.  Need a TIG to finish this out. 

I probably will put a 60-70mm TB on this and run it NA .

SO MANY PROJECTS- so little time

 

I will post up pics of the head exhaust ports. Not sure anything will come about from removing the liners, but I had a spare head to try. The later MN47 heads had better casting support for the liners, so they retained their shape better and held up longer. If I was staying with a round port head, I wouldn't even mess with the early 47. Much better combustion chamber on the mn47

http://forums.hybridz.org/topic/109975-turbo-intake-manifold-fabbing/

Little update

Haven't made much progress on the L28 part but have messed with the MN47 . After cutting on one for a while I think I found the port size that I am shooting for is 35mm(intake). It won't take much more than that without busting thru. That's a 4mm gain so I am pretty happy. I dropped the head off to a local machinist that has a flow bench and he is going to cut on it some more and do some flow testing. I left several chambers stock so we can do a direct comparison. I'm going with a 87mm and 89mm bore size. I figure most guys go over size when rebuilding. He is going to flow test with the 42mm intake and then the 44mm-again for direct comparison. The exhaust side is much easier , not a whole lot can be done.

I gave the machinist some flow bench numbers I found from some L builders to shoot for. He was like -whoa- that's pretty good!!

Since I have a plethora of these MN47 heads I am going to mount one on the L24 to get my FI conversion going. A gracious member here (Kenny Seo) basically gave me one of his that he had "beat" on pretty hard -including turbo charging. I dropped it off at the machinist to have pressure checked and cleaned to see if it was serviceable after it's 'Seo' life. The machinist returned to me cleaned up and said it was good to go!! The guides felt good and it was flat, "I'd run it"-he said. Since this head seems to like abuse I am going to port it and keep my other one stock to run on the L24. Confused yet- LOL- I know I am.

So the stock valved MN47 will go on the L24 with a paper thin HG to try and get CR close to 11:1. I'll run the bigger port head on the L28.      

Had some fun swapping parts for some cool pics. Carbs are fun-but FI opens up a lot of options

Edited February 12, 20178 yr by madkaw

I hope it's things work out like you're shooting for.

Does a square exhaust seal off on the mn47? Not to long ago someone was wanting to put carbs on a n47 and I wondered out loud if the intake gasket with the EFI notches would work. Hopefully he can read this and decide.

Is that an LD28 intake?

Round port to square exhaust is fine from what I've gathered .

yes Charles - LD INTAKE!

You gonna run the LD28 intake? I have thought about doing that...