Milling Question

JamesBaumann · Sep 6, 2004

I sent an email to the staff at racerwalsh asking how much you can mill off of a 2.3 head before you get into valve/piston interference and how what my compression ratio would be at in relation to how much I had taken off. Their reply was that it can be milled all the way down to the intake bolts and every .040" that I took off would increase my compression ratio by 1 point.

Now, here's my question. I'm not too familiar with compression ratio's, so what do they mean by 1 point? I know that stock compression on a n/a 2.3 is 9:1, so if I milled off .040", what would my compression ratio be at? I don't think it would be 10:1.

Anyway, if somebody could help me understand this I'd appreciate it.

bhuff30 · Sep 6, 2004

by 1 point, they mean from 9:1 to 10:1. I think 9.8-10.2: is a good place for a street 2.3, and you could probably get by with 10.5:1 if you have non-stock cam (ranger roller doesn't count).
Racer walshes guess of .040 is descent, but not very accurate. Calculate your compression for yourself. For every .007 you mill off, it removes 1 cc from the combustion chamber. If you mill .040, your compression goes to 9.7:1. Again, racer walshes estimate is ok, but it is inaccurate when you are calculating with low compression ratios or really high compression ratios because you don't have to remove as much at a high CR to reduce it by another point.
Like RW said, the max you can mill is to the intake bolts, which is around .120. That would put your CR at 11.5:1 which is definatly race gas only range.

TurboFlush · Sep 6, 2004

heheheheee, shaved heads are cool.
I just wish mine actually put out more power.
I still gota figure out what is not tuned right. I think it might be the intake restricting flow. (ford sierra but similar to mustang).

Ray III · Sep 6, 2004

First off the pre 91 motors had 9.0:1 compression to begin with, and the 91+ had 9.5:1. SO you must work off whichever you have.

.040" milled off for .7 to 1 point of compression sounds WAY off. On my 89 motor, I shaved .060", and from my calculations that much only took it to 9.7:1. The 91+ heads are a different shape and so there are probably TWO different guidelines...

Ray III · Sep 6, 2004

1980 2.3 Turbo mustang Ghia (On Standby)
1984 1.4CVH Escort GT WannA-be
1989 2.0ti Sierra SR Sleeper
1988 2.0 Sierra GL Project Goof-Rally
1986 2.8 Scorpio 4x4 SUHE
1990 2.0i DOHC Scorpio LX (confused)
1974 100cc G4 Kawasaki enduro {FOR SALE B.O.} -- 95% Restored!!!

Damn dude... Got Displacement?

JamesBaumann · Sep 6, 2004

So if milling off .040" would put somewhere around 9:7:1, then milling off .080" should put me somewhere around 10:4:1 or so?

I haven't decided just yet what I am going to use for a cam. Although, I am leaning towards a Ranger Roller. Would there be any problems with having a Ranger Roller and 10:4:1 compression?

Now, just a few more question. Say I did have about .075" - .080" milled off, what would I expect my power gains to be and what type of fuel would I want to use? I don't mind having to run high octane (91-93) fuel if it means I'll have a little more power.

bhuff30 · Sep 6, 2004

milling .080 would give you closer to 10.5:1.
do a search, but as I recall, dan'l milled .060 on his 91-93 that had 9.5:1 compression stock, and he ended up with 10.7:1 compression on the stock RR cam. He had some problems with pinging on 87 octane, but midgrade would fix it. You can try .080, but I bet you will end up running premium and/or retarding the timing a little. Go conservative and shoot for 10.0 or 10.3 by milling .060 or .070 respecivly.
My dyno calculator shows 13ft*lbs and 10hp gains for a jump from 9 to 10.5:1 compression

TurboFlush · Sep 6, 2004

Ray III said:
Damn dude... Got Displacement?

If you add them all together than yah, I guess so!
two of the cars are else where and one of them dosnt run. two of em just sit and look pretty.
projects!!! aghhhhh, soon I hope to get my 2.8 scorp running and sell two of the cars.

JamesBaumann · Sep 6, 2004

So if your dyno calculator shows 13ft/lbs. torque and 10 hp gains by milling off .080", then milling off .060" should give me about a 10ft/lbs. torque and around 8 hp gain.

So if I am running about 90hp. right now, then my milling will increase me by around 8 hp, the roller cam will give me between 12-15 hp I figure, so that will boost me up between 20-23 hp. That will sit me between 110-115hp. How much will porting and polishing boost my power output by?

Then there is the cold air kit and the exhaust.

freakintiger · Jun 13, 2005

bhuff30 said:
milling .080 would give you closer to 10.5:1.
do a search, but as I recall, dan'l milled .060 on his 91-93 that had 9.5:1 compression stock, and he ended up with 10.7:1 compression on the stock RR cam. He had some problems with pinging on 87 octane, but midgrade would fix it. You can try .080, but I bet you will end up running premium and/or retarding the timing a little. Go conservative and shoot for 10.0 or 10.3 by milling .060 or .070 respecivly.
My dyno calculator shows 13ft*lbs and 10hp gains for a jump from 9 to 10.5:1 compression

Holy thread ressurection Batman!

Anyway, did anyone actually do this? James you out there dude? If you did it chime in and let me know how it worked out!

Anyone else have some input?

Touring23 · Jun 14, 2005

FWIW, my new combo platter is up & running: 89 DP head milled .050", A237 roller cam straight up, +.020" KB pistons, Total Seal rings..... I cc'ed the head at 54cc and it's important to note the KB pistons have 4.5cc for valve relief. I calculate 9.5:1 when the head gasket space is included. Oh yeah. 87 Octane, 7* initial to ease into it during breakin. The lump runs great.

A person would be wise to use a compression calculator:
http://www.kb-silvolite.com/calc.php

140CILX-Coupe · Jun 14, 2005

intresting

bvav22 · Jun 14, 2005

what sort of cams can you put in the NA motors to add that 12-15 hp?

JamesBaumann · Jun 15, 2005

freakintiger said:
Holy thread ressurection Batman!

Anyway, did anyone actually do this? James you out there dude? If you did it chime in and let me know how it worked out!

Anyone else have some input?

Yeah man, Im here. I have my new head swapped on. Ported, polished, ranger roller cam & followers, shaved 0.50", and essentially no noticeable power gains. Quite disappointing. However, I am only using stock upper and lower intakes with a completely stock exhaust, so hopefully I'll notice some more considerable power gains when I get more flow in and out of the head.

In theory, your head should only flow as well as its weakest link, therefore, having a stock intake system and exhaust should defeat any increased flow of my cylinder head. Anybody with me on this or is this all just wishful thinking on my part? Even though my intakes and exhaust are stock, I still feel like I should have noticed a bit of gain in power output just with the head alone. Anybody else have any input?

As far as the milling goes, perhaps I should be trying MidGrade Fuel to be achieving maximum results from that mod.

Shawneebear93 · Jun 15, 2005

I think with an intake and exhaust it'll open up real nice.

freakintiger · Jun 15, 2005

JamesBaumann said:
Yeah man, Im here. I have my new head swapped on. Ported, polished, ranger roller cam & followers, shaved 0.50", and essentially no noticeable power gains. Quite disappointing. However, I am only using stock upper and lower intakes with a completely stock exhaust, so hopefully I'll notice some more considerable power gains when I get more flow in and out of the head.

In theory, your head should only flow as well as its weakest link, therefore, having a stock intake system and exhaust should defeat any increased flow of my cylinder head. Anybody with me on this or is this all just wishful thinking on my part? Even though my intakes and exhaust are stock, I still feel like I should have noticed a bit of gain in power output just with the head alone. Anybody else have any input?

As far as the milling goes, perhaps I should be trying MidGrade Fuel to be achieving maximum results from that mod.

Thanks for the info James. I've got to tell ya, between your results and Ray's, it's quickly turning me off to the whole N/A project I was putting together...currently I am seriously researching the turbo alternative...

Copy my exhaust in my sig, the pre-cat is a direct fit unit I got from an internet source, that may help your flow, I noticed an appreciable gain in power and this is the only real mod on my car...

JamesBaumann · Jun 16, 2005

freakintiger said:
Thanks for the info James. I've got to tell ya, between your results and Ray's, it's quickly turning me off to the whole N/A project I was putting together...currently I am seriously researching the turbo alternative...

Copy my exhaust in my sig, the pre-cat is a direct fit unit I got from an internet source, that may help your flow, I noticed an appreciable gain in power and this is the only real mod on my car...

The turbo alternative would probably be the way to go for you. It all depends on who you are and what you're looking for. Me, living in Canada, I have never had a turbocoupe enter my generally vicinity, so in order to do a turbo swap I'd more than likely have to piece everything together over ebay etc. and that seems like a pretty costly and frustrating idea.

The way I see it, a mildly modified n/a is all I need for cruising to work and back etc. each day. I'm hoping that I will notice considerable gains from my intakes and exhaust and I'll probably be happy enough with that. I wont be using a pre-cat seeing as though I have no emissions laws around these parts.

Chances are I'll build a 2.3 turbo Mustang one day just for fun, as well as a 5.0 Mustang (next project), so I'll satisfy my "go-fast" needs with that.

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