Engine swap Question - Ford Mustang Forum
 
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post #1 of 10 (permalink) Old 03-20-2017 Thread Starter
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Engine swap Question

I am new to the Mustang scene and recently bought a burned 03 GT automatic.The motor is junk and I had read that you can put a Mark 8 aluminum short block in with the heads off the existing motor. I am wondering if an earlier 90's lincoln motor is compatible with my 03 if I want to bolt on my top end and bolt it up to my stock 4R70W trans. Any info would be appreciated. Thanks.

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post #2 of 10 (permalink) Old 03-20-2017
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I'm doing that right now. You'll need a 93-98 Mark VIII. Some mods need to be done to the block, such as drilling a coolant passage and possibly clearancing the water pump boss to get the timing chain guides to clear if it's an early Teksid. You'll need different timing components, which I can help with later on if you decide to tackle this project.

You'll also need bigger cams to allow the higher compression of the Mark VIII pistons to bleed off. You'll need stage 2 or bigger cams to get it to run on pump gas with a good tune. The Mark VIII 3cc pistons is also where I ran into problems with my stage 3 cams. They are near a flat top instead of the standard 17cc GT pistons, so they need valve notches. My .25" Crown thickness Mk8 pistons needed .080" notched, leaving only .170" thickness. Not enough, it'll possibly cause a hot spot and blow a hole in the piston. Meaning you might end up needing to buy new pistons with notches in them. New rods and pistons cost me $1200, doubling the cost of the project for me.

So it can be done, and the power gains will be very nice. But it's not just bolting your 2v heads and intake onto the Mk8 block. You'll need machine work, bigger cams and springs, new bearings, rings, main bolts, rod bolts, head bolts, side bolts. Gaskets.

What I thought would be a cheap quick project got expensive in a hurry for sure

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post #3 of 10 (permalink) Old 03-20-2017
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Are you doing this just for the aluminum block? Another option might be to use an 05+ 3V block. I read something about one bolt on the 2V timing cover not being present on the 3V block, but it sounds like they don't need any other machining. I believe they had a slightly lower compression then the 90's 4V as well, so you 'might' be able to get away with a tune and 93 octane. If compression or valve clearance is an issue with whichever you go with, you can always just swap the 2V pistons and rods over and maintain the stock 2V CR and clearances. New rod bearings aren't that expensive anyway.

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2007 Mustang GT - 5-Speed, Airaid CAI, 4.10s
2001 Mustang GT "Mock 1" - 5-Speed, 03 Mach 1 Swap, 98 Cobra Intake Cam Swap, BBK CAI & Longtube Headers w/ H-Pipe, 4.10s 302 rwhp / 310 ft-lbs
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post #4 of 10 (permalink) Old 03-20-2017
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I just went through this, but stopped my build short. Using the 4.6 3 valve block with 2 valve heads will result in a compression ratio of around 11.5 to 1. Reason being is that the pistons on the 4.6 3 valve are approximately 6cc (some say around 3cc) while the 99-04 2 valve mustangs were 17cc. Im not sure about those 4vs.

The 3v aluminum block isnt missing a bolt hole, but rather has one in a slightly different location by about 2 inches but the block looks as if it has room for a bolt boss there. I believe that is the case of the teskid as well. If you pretty concerned about it, I suppose the block could be drilled to accommodate the hole BUT I DO NOT know what is on the other side of that aluminum lol.

PTV clearance would be the same, if your going to use cams you need to get different intake valves or have the current ones lips machined. MHS sells stock reground intake valves for like 48 plus shipping.
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post #5 of 10 (permalink) Old 03-21-2017 Thread Starter
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Thanks for the info. Seems like it may be more than I really want to get into at this point. Sounds like it would be an interesting project but time wise it might not be doable for me at this point. Thank you guys for the info and if I decide to do it in the future at least I have an idea of what I need to look out for.
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post #6 of 10 (permalink) Old 03-22-2017
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Quote:
Originally Posted by Screaming04Gt View Post
You'll also need bigger cams to allow the higher compression of the Mark VIII pistons to bleed off. You'll need stage 2 or bigger cams to get it to run on pump gas with a good tune.
Wouldn't the increase in valve overlap from bigger cams bump up the effective compression ratio?

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post #7 of 10 (permalink) Old 03-22-2017
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Taken from a member in Hondatech:

"Overlap and Compression- A very common idea, although for the most part incorrect, is that overlap bleeds off compression. Overlap, by itself, does not bleed off compression. Overlap is the angle between the exhaust closing and intake opening and is used to tune the exhaust's ability draw in additional intake charge as well as tuning idle vacuum and controlling power band width. Cylinder pressure is generated during the compression cycle, after the intake valve has closed and before the exhaust opens. Within practical limits, an early intake closing and late exhaust opening will maintain the highest cylinder pressure. By narrowing the Lobe Seperation Angle 'LSA' for a given lobe duration, the overlap increases, but the cylinder pressure can be increased as well. Thus cylinder pressure/compression can actually increase in this scenario, by the earlier intake closing and later exhaust opening. By increasing duration for a given LSA, the overlap will increase, the intake closing will be delayed, and the exhaust opening will occur earlier. This will decrease cylinder pressure, but the decrease/bleed-off of compression is not due to the overlap, it is due to the intake closing and exhaust opening events."

So the overlap doesn't bump compression. It sounds like when both intake and exhaust valves are open at the same time, more air is escaping the cylinder, effectively dropping dynamic compression.
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post #8 of 10 (permalink) Old 03-22-2017
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Quote:
Originally Posted by Screaming04Gt View Post
Taken from a member in Hondatech:

"Overlap and Compression- A very common idea, although for the most part incorrect, is that overlap bleeds off compression. Overlap, by itself, does not bleed off compression. Overlap is the angle between the exhaust closing and intake opening and is used to tune the exhaust's ability draw in additional intake charge as well as tuning idle vacuum and controlling power band width. Cylinder pressure is generated during the compression cycle, after the intake valve has closed and before the exhaust opens. Within practical limits, an early intake closing and late exhaust opening will maintain the highest cylinder pressure. By narrowing the Lobe Seperation Angle 'LSA' for a given lobe duration, the overlap increases, but the cylinder pressure can be increased as well. Thus cylinder pressure/compression can actually increase in this scenario, by the earlier intake closing and later exhaust opening. By increasing duration for a given LSA, the overlap will increase, the intake closing will be delayed, and the exhaust opening will occur earlier. This will decrease cylinder pressure, but the decrease/bleed-off of compression is not due to the overlap, it is due to the intake closing and exhaust opening events."

So the overlap doesn't bump compression. It sounds like when both intake and exhaust valves are open at the same time, more air is escaping the cylinder, effectively dropping dynamic compression.
If I read that article right, it's saying you can increase dynamic compression by increasing overlap. Duration can also play a factor in overlap but you can directly affect cylinder pressures with LSA.

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Procharged--cammed--Lito tuned--coilover suspension
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post #9 of 10 (permalink) Old 03-22-2017
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Duration and overlap all play a part in it. The most cruicial part in dynamic compression is the intake valve closing point.

1998 GT
Rebuild in the works. New crank, 2013 Boss rods, srp .020 over flat top pistons with valve reliefs, 12:1 compression, ported pi heads, comp xe278ah cams.
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I thought the general saying was running more aggressive cams lower dynamic compression ratio at lower rpms, yet increases it at higher rpms due to volumetric efficiency of the engine.
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