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Discussion Starter · #1 ·
what is the max hp i can count on out of my stock 4.6 romeo block without needing to up grade for my engine build
 

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i have asked that same question and i have heard 450 hell i have been told even up to 600 i dunno for sure though.
 

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Discussion Starter · #3 ·
fixing to start my engine build. wanting to get a 2.1 kb sc ,forged internails for my motor.wanting to run obout 12lbs of boost but not sure if my stock block can hold up.
 

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yeah i have heard the same thing, our blocks can take up to roughly 600 horses before you need to upgrade really seriously.......but dont quote me....jus different people will tell you different things. if you really want to go balls to the walls make sure you find a custom mechanic that will tell you the "no sh*t" truth....thats jus my opinion
 

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im going to guess arround 450 ...600 is a little crazy...it also depends on what you do to it. if you want a supercharger with crazy boost your going to want forged internals.
 

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sorry didnt read all of your posts....umm the block will hold 600 im pretty sure
 

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block will hold 1000+. It's cast iron. Internals it is good to stay around 400rwhp. People like Unix have made closer to 500 but it some will say borrowed time. If you want to be safe stay around 400. The rods and pistons in these car's stock arent the sturdiest of all
 

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Discussion Starter · #8 ·
just tired of the terminators having all the fun. just like the idea of making a mildly modded terminator feel bad
 

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just tired of the terminators having all the fun. just like the idea of making a mildly modded terminator feel bad
Yeah it makes you feel good! ;) LOL
 

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As far as the blocks go, there isnt any real difference between the Cobra block and ours, if we're talking about a cast iron blocks. So if you biuld the rotating assembly to hold the power, it will hold. Everyone says the rods are the weak point, but lately most of the engine failures have been due to a lean condtion breaking the top of the piston. And some of those engines broke at 400. So as for stock rotating assembly, 400-450, as for the engine block, dont worry it will be a while before you get to that threshold.
 

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+1 Exodus. i ran 380RWHP and beat the **** out of that motor for a year.. wrapped it up to 6500 all the time. did headers and a new mass air sensor and it ran for a week then took a poop. i ignored the fact that it was running 12.5:1 air/fuel under WOT, and that was a bad idea. one night it spiked to 14:1 and it detonated and broke a ringland. took it all apart and the rods looked new. nothing bent or stressed. all the bearings were good too. it could have taken a much bigger beating if i would have got it tuned after the headers and new MAF. i think 450 would be a good stopping point on the internals. i've never heard of anyone breaking a block. they're good for well over 1000 horsepower.
 

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This is a common question and there is tons of info on this forum as well as other mustang forums out there.

Firstly, you have to determine what 4.6 block you have. There are aluminum and cast iron. Don't assume because your mustang was a certain year that it's automatically aluminum or cast iron. I have a 2000 GT and thought, after reading much info, that it was aluminum block. It's actually a cast iron windsor block!

Another big variable is the manufacturer. There are Romeo blocks, Windsors, and Teksid's. The earlier aluminum Teksid block is considered the best of all, given its strong reiforcement webbing and exotic origin (teksid is an Italian manufacturer that makes blocks for ferrari!). It's extremely difficult to tell the difference between aluminum blocks, usually it comes down to removing the timing cover to see a "T" engraved for teksid or a "OH" for a windsor block (ohio).

Here are good rule of thumb applications, stock meaning STOCK components, modified meaning forged internals. This is a guildline for street engines, meaning 100k plus miles without stripdowns and reliable performance:

Teksid Aluminum (usually found on 96-99 4v cobras) = 600 stock, 1000 plus modified

Windsor Aluminum (usually 99+ GT's and Cobras) = 500 stock, 650 modified

Windsor Cast Iron (usually 99+ GT's) = 400 stock, 600 modified

Romeo Aluminum = 550 stock, 700 modified

Romeo Cast Iron = 450 stock, 600 modified


Another big variable is the age and wear of the engine. All these above ratings and for good condition engines, either low mileage or well cared for, not 250k plus clunkers with burned rings.

Remember, year approximations for blocks have always failed me in reality- too many exceptions to the rule. That means LOOK at your block and figure out what it is- there are many pages with info on how to tell a Romeo from a Windsor from a boat anchor.

Easiest test to see if you have aluminum or cast iron: glue a magnet to the end of a stick or grab a magnetic pickup tool at the autoparts store. Stick it in-between the gap between the intake manifold and the block, right at the center of the 'V" of the engine. If it sticks you got iron, if there is no stick it's aluminum.
 

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I find it interesting that in your examples you rate modified cast iron block as withstanding lower horsepower than aluminum blocks. Everything I have ever read, here or on engine builder's web sites, has said otherwise. A cast iron 4.6 block with forged internals should hold up to 1000 rwhp.
 

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Here are good rule of thumb applications, stock meaning STOCK components, modified meaning forged internals. This is a guildline for street engines, meaning 100k plus miles without stripdowns and reliable performance:

Teksid Aluminum (usually found on 96-99 4v cobras) = 600 stock, 1000 plus modified

Windsor Aluminum (usually 99+ GT's and Cobras) = 500 stock, 650 modified

Windsor Cast Iron (usually 99+ GT's) = 400 stock, 600 modified

Romeo Aluminum = 550 stock, 700 modified

Romeo Cast Iron = 450 stock, 600 modified

Whos Rule of thumb,Yours?

Where did you Dream up these numbers?
 

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Maybe he means that the forged internals that were the least strong of the forged internals he looked at? Who knows?

What I do know is that Jive Pepper should have blown it up on the dyno along with every other terminator out there that has a big cotton candy maker if those numbers were right. lol
 

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Teksid Aluminum (usually found on 96-99 4v cobras) = 600 stock, 1000 plus modified

Windsor Aluminum (usually 99+ GT's and Cobras) = 500 stock, 650 modified

Windsor Cast Iron (usually 99+ GT's) = 400 stock, 600 modified

Romeo Aluminum = 550 stock, 700 modified

Romeo Cast Iron = 450 stock, 600 modified

As I said earlier, this is for a reliable daily driver that can go 100k+ without teardown. And these numbers are from what I have observed. Personally built or helped build Romeo and Teksid aluminum, have a windsor cast iron block project going now. I am no professional, just an enthusiast.

Should have made a distinction between Terminator 03-04 cast iron Romeo's and Romeo GT blocks made from 91 on. Yes the Terminator block is insane, 1000hp+, my bad.
 

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Teksid Aluminum (usually found on 96-99 4v cobras) = 450 stock, 1000 plus modified

Windsor Aluminum (usually 99/01 Cobras) = 450 stock, 650 modified

Windsor Cast Iron (usually 99,00, and early 01 GT's) = 450 stock, 1000+ modified

Romeo Aluminum (did they even make these?) = 450 stock, 650 modified

Romeo Cast Iron (01-04 GT's and 03/04 cobras) = 450 stock(gt) , 750 stock(03-04 cobra) 1000+ modified
thats more what i'm thinking


i'm not entirely sure what you're goin for but basically any modular motor other than the 03/04 cobras came with cast rods from the factory and the rods are only good to about 450RWHP before they go south. the blocks for that matter.. 650 is about the max for a non-teksid aluminum block. all of the cast iron blocks should easily withstand 1000 hp, as well as the teksid aluminum blocks. this is what i've learned.. maybe i'm wrong but i don't think i am.
 
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