L28 Build - Suggestions/Advice Please

[jy.s30z]

Hello fellow z members,

This is my first post on CZCC. 
I am in the process of my first engine build... This car will only be for street (daily summer) use and will have ~10.2:1 CR, the build so far consist of the following:

-N42 Block 0.010" decked, 0.020" bored out - Completed

-Forged flat top pistons 0.020" oversized. Machined to all stick 0.013" above deck height - Completed

-Felpro head gasket (.039" gasket - 0.013" deck height = 0.026" P/H clearance) - Completed

-L24 prepped & balance rods - Completed

-P79 Head 0.080" decked (46cc chambers), using N47 valves (0.080" longer) - Completed

-Resurfaced rocker arms - Completed

-0.080" Cam tower shims - Completed

-Valve job - Completed

-6-2-1 headers - Completed

-Megasquirt 3 - Completed

-30lb injectors - Completed

-LS COP - Completed

-50mm ITB's with custom long tapered intake (50mm to 37mm) - Completed

-New ARP rod bolts - Completed

-Racer Brown 325R camshaft from Delta Cam - Completed

-Rebello Valve Spring A - Completed

-Fidenza aluminum flywheel (Stock LUK Clutch) - Completed

-Dual 12" electric fans & Aluminum Rad - Completed

Still need to do:

-3" Exhaust - Not Completed

-Port match head to intake (37mm) - home port job - Not Completed

-New Fuel Pump and Regulator - Not Completed

-Assembly

 

The reason for this post is to get any opinions/tips/suggestions on this build before I start porting the head and begin assembly. 

What type of HP do I expect to see with this build from your experiences? 

Lastly, I attached a picture of my cam specs. Any suggestions on dialing in this cam to suit my build?

Thanks in advance!

Edited August 7, 2018 by jy.s30z

[madkaw]

Flat tops have any reliefs? 

So cam is 480 lift and what duration?

I would have gone higher on the CR with what you have.

Becareful how deep you go on that port match. I haven’t dug into a 79 , but I know my MN47 would not open that big 

[jy.s30z]

8 minutes ago, madkaw said:

Flat tops have any reliefs? 

So cam is 480 lift and what duration?

I would have gone higher on the CR with what you have.

Becareful how deep you go on that port match. I haven’t dug into a 79 , but I know my MN47 would not open that big 

Thanks for the response, The cam spec attached shows the duration (254 @0.05"). 

The flat tops don't have any reliefs, I will be going through the clay procedure check.  What clearances does everyone recommend?

The CR from my calculations will be 10.27:1 - I want to run on 91 octane comfortably.   What CR do you recommend? 

The P79 heads to my understanding have the same combustion chamber and intake ports as the famous P90.  The difference is in the exhaust - P79 has the steel liners.

Edited August 7, 2018 by jy.s30z

[madkaw]

My thoughts would be if I spent the money for forged pistons I would take full advantage of their durability with respect to rpms and CR. I would go with as big of a cam as possible and run 11:1+ , but 91 octane you are probably in a safe region.

With MS3- which is what I run- with full control of spark you can push the envelope with timing and dial it in more safely than a dizzy, but you probably already know that .

As far as porting, my MN47 Is also very similar to to the 79&90 heads, but unsure of the port structure. I could only go 35mm before getting the walls to thin. This is 35mm way down in the hole . So just matching ports of intake and head you might not see any issues

[siteunseen]

20 minutes ago, madkaw said:

Flat tops have any reliefs? 

So cam is 480 lift and what duration?

I would have gone higher on the CR with what you have.

Becareful how deep you go on that port match. I haven’t dug into a 79 , but I know my MN47 would not open that big 

Will he need the shorter valve seals with that cam Steve?

Sounds like you've done your research!  I like it.  Can't wait to read your progress.

[madkaw]

And where’s the damn pics ?

[madkaw]

What have you done with valve seat and bowl areas? 

[jonathanrussell]

@madkaw....MN47 has smaller ports than P79/P90. So, I assume there is less material to work with.

@Diseazd...you have built the engine above many times. Doesn't it require switching to the longer valves from N42/N47? Didn't see that mentioned in the list above.

 

J

[jy.s30z]

16 minutes ago, madkaw said:

My thoughts would be if I spent the money for forged pistons I would take full advantage of their durability with respect to rpms and CR. I would go with as big of a cam as possible and run 11:1+ , but 91 octane you are probably in a safe region.

I have another stock cam that I can send for a different grind.  Originally I was going with no porting, now I am worried that my lift is too low and I'll be leaving some on the table.

18 minutes ago, siteunseen said:

Sounds like you've done your research!  I like it.  Can't wait to read your progress.

Thanks!  I've done so much research on this build, especially on the intake design.  I will post pictures soon.

 

14 minutes ago, madkaw said:

What have you done with valve seat and bowl areas? 

I did a 3-angle valve job unfortunately before I decided to do the porting. Other than that, nothing has been done 'yet'.

 

3 minutes ago, jonathanrussell said:

you have built the engine above many times. Doesn't it require switching to the longer valves from N42/N47? Didn't see that mentioned in the list above.

I am using the longer N47 valves. See 5th bullet in the list above.

[jy.s30z]

This picture is of the 'unfinished' intake.  Still needed mounting holes & injector holes put in.

[Diseazd]

1 hour ago, siteunseen said:

Will he need the shorter valve seals with that cam Steve?

Sounds like you've done your research!  I like it.  Can't wait to read your progress.

No Site, because the springs are shimmed up and the valve is .080 longer. He can go stock valve seals. BTW jy.s30z.....don’t forget the spring shims....don’t see them mentioned.

Edited August 7, 2018 by Diseazd

[madkaw]

Well it might be too late, but with a steady hand you could blend the seats and at least do the short side radius. The exhaust liners make a sharp edge on the short side radius and it really needs attention . 

Cam - go as big as will clear your flat tops. These engines love cam and you won’t give up drivability . You have pistons good for 8k + , take advantage of it.