1995 EFI 300 turbo build

n8in8or

Well-known member
I started a build thread on the Big Block page, but since it has transitioned to a turbo build I figured it was more appropriate to have the build on the Turbo, Supercharger and Nitrous page for more visibility.

Here is the original thread: viewtopic.php?f=2&t=77784

Basically, I'm doing a budget-ish turbo build on a 1995 EFI long block that I am going to put in my 1994 F150 4x4 that is going to be used as an all around useful pickup and offroad toy.

Reading a few other builds and with input mostly from pmuller9 I have landed on this basic combo:

re-ring and bearing short block
HV oil pump
Fel Pro 1024 head gasket
ARP head studs
ported and polished EFI head
custom hydraulic flat tappet cam
probably custom intake manifold made from an EFI lower with a plenum attached to it
EFI exhaust manifolds with a Y collector for the turbo feed
Megasquirt piggyback (with the thought of switching to a 5.8/E4OD ECM so I can get a 4500 rpm shift point)
As yet undetermined turbo - I have an Ebay HX40 needing a rebuild that is a leftover from playing with my 6.5 diesel. I am going to research if there is a wheel and housing combo for this that will work well in this application. Otherwise I will go with a different Ebay turbo since I've had good luck with the one in my diesel.

I have done a decent port & polish job on the head already, but since I'm definitely going turbo now I'm going to open up the chamber so I can get my static compression ratio down around 8:1. I will be posting pics as I make progress on that. Here are some pics of my progress so far:

Intake port: I'm going to try to cut the valve guide down even further - mostly make it narrower intake port 1.19.18.jpg
Exhaust port: I plugged the thermactor port with a pipe plug and then after grinding the boss down I applied epoxy over the hole. I am going to try applying a second coat of epoxy in an attempt to make the roof even smoother and more consisten exhaust port 1.19.18.jpgchamber in cylinder 1.19.18.jpg
Combustion chamber: I left the fast burn features alone with the exception of polishing, but now that I'm going turbo I will be laying these walls back 45* to decrease chamber volume and increase cylinder fillchamber 2 1.19.18.jpgchamber 1 1.19.18.jpgbottom overall 1.19.18.jpg

I welcome all insight as the build progresses because this is not only my first 300 build, but also my first gasser turbo build. Thanks in advance!

-Nate
 
I got the cheapy Comp Cams cc measuring kit today so I could see how I was doing so far and can see how far I need to go. I sure wish i had ponied up for the expensive one with the burret instead of the flask, but it got the job done.

First I measured the combustion chamber and I am at 69.5cc in my cuttent state - which is cleaned up around the plug and polished around the valves.

39C4B8A5-16DE-45B6-BC6B-757EF9E71AC5.jpeg

Next I measured the piston dish and that is 25cc.

Finally I reinstalled the crank and 1 rod and piston and I measured a deck clearance of .018 (much less than I expected!).

So right now I’m at 8.71:1 compression. Hopefully I can remove enough from the chamber to get close to 8.0:1. If I can get the chamber up to 80cc then I’ll be at 8.02:1, but I doubt I’ll get it that open. I’ll have to look into conical faced valves to help a little too I think.
 
Don't worry about getting a specific combustion chamber volume.
Get the finished design you want and make the volumes the same.
There are higher volume hypereutectic dish pistons available with 30cc or more.
 
pmuller9":2n61l6eu said:
Don't worry about getting a specific combustion chamber volume.
Get the finished design you want and make the volumes the same.
There are higher volume hypereutectic dish pistons available with 30cc or more.

Good advice. At first I was thinking I ddn’t like that plan because I’m trying to keep this cheap and easy, but as I thought about it more that does make sense: It’s probably cheaper to get a set of pistons than it is to get a set of conical face valves I’m guessing.

So if I’m recontouring the combustion chamber would it make sense to stick with the D shabed piston dishes or is a full round more appropriate or does it not really make a difference at this point?
 
The majority of the aftermarket SBC valves will have a concave head to save weight.

The "D" dish pistons won't have enough volume.
The round dish will get you closer.
The step dish piston that is for the HD truck engines definitely have plenty of volume and some other advantages that can be discussed later.
 
pmuller9":fu5uh15s said:
The step dish piston that is for the HD truck engines definitely have plenty of volume and some other advantages that can be discussed later.

I was just looking at the HD step dish pistons. I like that they still have the quench pad. It looks like if I can hit a 75cc chamber I’ll be right around 8:1 compression with those. They’re $116 on Summit, so not a terrible price either, though then I’d have to have them pressed on the rods. I have a press, but I’d be worried about damaging the pistons.

I’m going to be heading out to start grinding on the head shortly. Hopefully I can get a chamber roughed in pretty well today and know where I stand.

I also noticed that most of the valves did have a dished face, so i guess that is a moot point.
 
The small end of the connecting rod gets heated when you install the piston pins.
There are connecting rods heaters available.
google connecting rods heaters for more detailed info on press fit pin installation.
 
Well that went faster than expected. I bought some new carbide burrs from McMaster-Carr this week since I knew I had a lot of material removal to do this weekend.....what a difference new, quality burrs make! I know that sounds dumb, but I’ve only ever used swap meet burrs before so I didn’t have a proper frame of reference. Man do they cut theough the metal like butter and they also chatter less. Very impressed.

So anyway. I’m pretty happy with the shape I achieved. I cc’d it and found that I’m at 74cc - that puts me at 8.39:1 with the stock pistons and 8.09:1 with the HD pistons. I imagine I’ll gain a little volume with the concave valve heads as well, though I doubt that accounts for much.

Here’s what it looks like so far. It still needs some clean up and polishing as this is just carbide finish with a little 80 grit sandpaper roll.
0FB465A9-FD9A-479B-9B2A-1C9A73D7F537.jpeg

One place I may remove a little is where the burr is placed on the outside of the valve seat. I’m not sure if this will help or not.
02F5C0BE-9C7A-47BF-9F00-041FE004FF30.jpeg
DCB9FA9C-C8EB-4543-AA99-63695F36090E.jpeg
7239339E-1A51-42D8-9B78-E0D2AF7B49C1.jpeg
807108C4-AB5D-415A-8D98-7811CF53975B.jpeg

I’m going to make a template now so i can start marking out the other chambers.
 
n8in8or":2cuqtjn1 said:
One place I may remove a little is where the burr is placed on the outside of the valve seat. I’m not sure if this will help or not.

No real help there since the cylinder wall is also shrouding at that point.
Nice work!

It looks like you will also hit the 75cc mark with the new valves.

When you finish using the sandpaper rolls remove the sharp point between the two valves with a radius.
 
Thanks!

I was thinking it might help direct flow to/from the quench area if I ground in the axis that the burr was laying, but I can also that if I did that it would probably hurt flow from the sides so I will heed your advice and leave it alone.

Ok I will be sure to put a radius in. Is there a target radius? I’m sure part of the function of the radius is to eliminate hot spots, but is there also a flow advantage? Do I also put a radius where the quench shelf meets the chamber? If so, what radius? Thank you for your help!
 
I made a template by first starting with multiple layers of masking tape. I cut the outline of the chamber out with an exacto knife.
6E50F6D9-FA00-4076-8BBE-64422FA5594E.jpeg

After that I transferred the tape to some cardboard and cut the opening in the cardboard to match. I found it was really hard to line up the template properly so I added the head bolt hole cutouts to the template and then it was easy to line up.
32EA155E-A718-481F-939B-2924DB812ADF.jpeg

I then laid it on each cylinder and traced the template with a scribe.
AAF58334-1195-41AA-8C88-A13647BD3F87.jpeg

I ended up getting 2 more cylinders roughed in before calling it quits for the day.
58DB3FA8-5A06-4B9A-B02D-30E5758DE1C7.jpeg
 
n8in8or":26iy1s0q said:
Ok I will be sure to put a radius in. Is there a target radius? I’m sure part of the function of the radius is to eliminate hot spots, but is there also a flow advantage? Do I also put a radius where the quench shelf meets the chamber? If so, what radius? Thank you for your help!
OK So maybe radius is too much of a term. Just round off all edges so they aren't sharp including all the way around where the chamber meets the head surface.
Look back at the example head and give it just a little bit more than that.
Yes, it is all about preventing hot spots.

Looking good around the intake valve guide.
You realize you may have to offer this porting service to the general public on this forum. :D
 
Thank you for the kind words, sir. And once again, thank you for providing the assistance and also for providing the examples to work towards!
 
Made some more good progress today. I got the last 3 chambers profiled with burrs and then hit them with cartridge rolls - first 80 grit, then 180 grit. I also got all of the intake valve guides profiled. Lastly I hit the #6 chamber and exhaust bowl with a 120 grit buffing pad. I’m going to at least go up to 180 grit and then see how it looks. I also have 320 and 400 grit pads, but I’m not sure if I’m going to see enough difference to warrant the time, we’ll see.
A9D850D2-CE8D-4587-B374-C4340C6C16C8.jpeg15DE8E9D-CF43-46E9-A652-39730D2E36CF.jpeg
 
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