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Discussion Starter · #1 ·
New post, so I'm not accused of gravedigging my own topic.

I'm back from my trip, and working on my heads again. I bought a cheap valve spring compressor from my local parts store, and broke it. Perseverance got all the valves out, finally, and now I can grind in from the valve side. It's really easy to figure out what to do once you're looking at it. The intake side, like everybody says, is absolutely disgustingly huge. I'm tempted to add some JB weld to give it more material. The exhaust side, however, demonstrates why our cars give us problems when we hit the accelerator.

I wish I took a picture before I cut away at it, but anyone that's thinking of doing similar work, there's a step-ledge on the valve guide boss that forms a 90 degree angle, jutting right into the flow path. I thought maybe they put it there for venturi effect, but then why wasn't it on the intake side? So I called Tom Morana (because he's cut 220 cfm int. & 180 cfm exh. 3.0 heads) and he said to just cut it down. I'll post some pictures when I'm finished the intake side.

I just need to track down some valves. Tom used to offer 1.730" intake & 1.500" exhaust, but he said he'd need to get the exhaust ones custom cut. That's around .070 over for intake, and .120 over for exhaust, which is HUGE! If I can't get those, my next option is .015 over, which isn't that impressive.

I'm so excited to get this project done, but with how expensive the valves and machine work are going to be, it probably won't be ready to swap in until mid to late August. Keep your fingers crossed for me.
 

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Let us know how it goes. Larger valves may reduce the low end torque slightly (you might not notice) but that would sure bring a smile when you put your foot down.
 

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Discussion Starter · #3 ·
Yup, that's what I'm hoping. This engine has plenty of torque, so I don't mind too much if it goes down. Unless it goes down to I4 levels.

So as promised, here's what I did to the combustion chamber:


I just smoothed it out and took away any sharp edges & casting flaws to remove noticeable hot spots. The head will look a lot better when it gets resurfaced (read: milled for compression).

And here's the modified exhaust valve guide boss:


I wish I took a before photo, but anyone that's looked through the valve-side knows the ledge I'm talking about, and you can see it's been smoothly ground away. Hopefully this'll let the exhaust-side breathe as well as the intake side, and open up some ponies. I apologize for how ugly it looks, I sprayed it liberally with fogging oil before taking these pics. I don't want it to rust while it's waiting for me to find valves & springs for it.

I have pics of the intake port, but they came out terrible, so I'm leaving them out. All I did was smooth it out a touch so carbon won't build up.
 

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Those heads dont look too happy. You plan on milling them up to maintain the airflow? or are you gonna change that up?
 

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Discussion Starter · #5 ·
Those heads dont look too happy. You plan on milling them up to maintain the airflow? or are you gonna change that up?
They'll look happier when they're cleaner. Tom Morana said I can mill them .030 to raise compression, but I want to see if my local shop can take .040 off without any problems with the LIM and pushrods, which would bring compression up to around 10.3:1
 

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They'll look happier when they're cleaner. Tom Morana said I can mill them .030 to raise compression, but I want to see if my local shop can take .040 off without any problems with the LIM and pushrods, which would bring compression up to around 10.3:1
Why increase the compression ratio?
 

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mediarocker
Originally Posted by: Dubeckyj
They'll look happier when they're cleaner. Tom Morana said I can mill them .030 to raise compression, but I want to see if my local shop can take .040 off without any problems with the LIM and pushrods, which would bring compression up to around 10.3:1


Why increase the compression ratio?​
more POWAAHHHH!!!!!!!!!

 

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How much more power could you net from increasing compression ratio this little bit? Wouldnt it stress it more if one were to consider FI?
 

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How much more power could you net from increasing compression ratio this little bit? Wouldnt it stress it more if one were to consider FI?
In my humble opinion,
If detonation is suppressed and the starter can still turn the motor over, there is no negative effect to adding compression to an engine.

A boost in static compression ratio is commonly cheaper then forced induction and there is never any lag - the increased compression is ALWAYS present at every speed.

I just read in MM&FF that guys are now running 9.5:1 (yes, nine and a half, a previous N/A pump gas limit) compression in forced induction 5.4s... Simply because the new computers can adjust the ignition timing and fuel mixtures so quickly and precisely that detonation isn't an issue. Definitely food for thought!
 

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In my humble opinion,
If detonation is suppressed and the starter can still turn the motor over, there is no negative effect to adding compression to an engine.

A boost in static compression ratio is commonly cheaper then forced induction and there is never any lag - the increased compression is ALWAYS present at every speed.

I just read in MM&FF that guys are now running 9.5:1 (yes, nine and a half, a previous N/A pump gas limit) compression in forced induction 5.4s... Simply because the new computers can adjust the ignition timing and fuel mixtures so quickly and precisely that detonation isn't an issue. Definitely food for thought!
I always figured if you put up too much compression, you would need to back off a bit to run a charger.. didnt figure this.

I'm actually not surprised they can run 9.5:1 in FI considering that the ranger guys have been doing it on a 9.3:1 vulcan. many of them with the tom morena stroker kits which i believe raises the ratio even further.

How much compression ratio do you plan on running?

I'm just curious. i'm learning here.. :p
 

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Discussion Starter · #12 ·
I always figured if you put up too much compression, you would need to back off a bit to run a charger.. didnt figure this.

I'm actually not surprised they can run 9.5:1 in FI considering that the ranger guys have been doing it on a 9.3:1 vulcan. many of them with the tom morena stroker kits which i believe raises the ratio even further.

How much compression ratio do you plan on running?

I'm just curious. i'm learning here.. :p
I'm not sure who that's aimed at, but I already mentioned ~10.3:1. I did some math, and taking .030 off the heads would take it to 10.0:1, but I'm too lazy to do the math for .040, so I figure it'll just be higher than 10:1. In theory, with the combustion chamber smoothed out, the absence of hot spots will reduce the chance of detonation. I have no intention of going FI. But FYI, the Saleen S7 TT has twin turbos pushing 5.5 psi at 11:1 compression, so anything is possible. I just don't want to add octane boost to my tank at every fill-up, nor have to drive to the track every time I'm low on gas.
 

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Discussion Starter · #13 ·
Alright, I ordered my valves today, and I'll be ordering the springs and friends on Monday when paypal stops being a turd. I'm excited to see what these heads will do. I can't take it to a machine shop until the valves come in, so no updates for the next two weeks or so.
 

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You probably already thought about this.. but are you gonna be able to run those valves with overlap (if you decide to cam them) without any interference?
 

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I like what you are doing and am very interested on how it turns out. Keep us posted and good luck!
 

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Discussion Starter · #19 ·
You would happen to be willing to share the part numbers and vendor who you're getting the valves from?
They're from SI, and they're custom. At $30 a valve, I don't think you'd want to go that route unless you're a retard like me. Tom Morana offers .020-over ridiculously-high quality SS valves for $15 a pop, but that wasn't enough for me. SI has stock dimension valves for our application listed here: SI VALVES but I don't know the price of them.

You probably already thought about this.. but are you gonna be able to run those valves with overlap (if you decide to cam them) without any interference?
Camming is a huge part of the future of this engine build, but so is stroking it. After all the hassle I went through replacing the engine, I'm a little reluctant to go through it again, so the bottom half will wait a while. That in mind, with the heads finished, I'll play with the valves a little to see how far they come down and if there's any problems. With the 1.8:1 rocker arms I'm throwing on afterwards, I'll already be getting 0.5" lift at the valve (roughly 0.056" more), it's just duration that won't be changed. They shouldn't meet the pistons, but I'll be double-checking before installation.
 

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Camming is a huge part of the future of this engine build, but so is stroking it. After all the hassle I went through replacing the engine, I'm a little reluctant to go through it again, so the bottom half will wait a while. That in mind, with the heads finished, I'll play with the valves a little to see how far they come down and if there's any problems. With the 1.8:1 rocker arms I'm throwing on afterwards, I'll already be getting 0.5" lift at the valve (roughly 0.056" more), it's just duration that won't be changed. They shouldn't meet the pistons, but I'll be double-checking before installation.
Have you also considered the valves interfering with themselves due to their oversize?
 
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