Iron to Aluminum block/Burr finish to smooth

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Frankshaft
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Iron to Aluminum block/Burr finish to smooth

Post by Frankshaft »

I wasn't going to post this, it's my info, don't usually post results. In Lou of a bunch of threads relating to the thread title, this engine or engines I suppose, covers 2 subjects at once. The belief that the Burr finish is the end all be all, and that aluminum blocks make less power than an equivalent iron block engine. Well, this particular test,, was interesting, and the kind of stuff I am involved with on almost a daily or weekly basis, I have TONS of info like this, but most guys on here want to discount it, so, I say, to bad, I won't share. Oh well, why would I care, lol. It dawned on me this morning, about this test we did earlier in the year. 601 inch big block Ford it happens to be. Likely one of the highest horsepower Super Cobra Jet headed engines in the country. Engine was originally built with a Ford motosports iron block. Ford's equiivalent to a gm bowtie. Beefy, thick, strong, stable, etc. 4.5 inch stroke lunati crank, Oliver billet rods, 625 custom age bolts, custom Pistons, gas ports, .043/.043 3 mm rings, back cut top, Napier second, and low tension oil. Heads are the previously​mentioned Ford motosports Super Cobra Jet heads. 2.25 intake valve added, with my specific valve job. Engine has a dry sump, and a vacc pump. Intake is a rare Kasse cast tunnel ram. 2 small csu dominators. Sid roller cam, etc.

Engine is run A LOT. The car is a 3350+ pound mustang bracket car. It's​run every weekend somewhere. There is pictures of the heads on speedtalk, it was one of the finish threads. Not sure if it was Vizards, or Brad hs. I lost the pictures, they were in my crashed old phone. Those pictures show the aggressive cuttered finish. So, this past winter, we wanted to try a smooth finish. At the same time, they found a really good deal on an old good shape Allen Root aluminum block. 100% of the parts we're swapped over, after re machining Everything. Touched​up line hone, decks, cylinders were sized for the Pistons. Bores were 4.560 or something, made them 4.610. EVERY single piece was the same from the other Block. Except obviously fresh rings, bearings and gaskets. So, the only changes, smoothing the ports, 60 grit, from aggressive cuttered finish. To be fair, the ports were larger, as the aggressive finish needed to be ran over with a smoother carbide, to remove all the deep texture, and the Block. Went from iron, to the aluminum.
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Re: Iron to Aluminum block/Burr finish to smooth

Post by Frankshaft »

I should add, iron Block rough finish left, aluminum block smooth finish right. Notice manifold vacc. Same pump, pulleys, etc etc, it UP vaccum. Also, notice the Engine on right has better more consistent bsfc's. This on Q. The aluminum Block/smooth finish wanted less jet to make MORE power, same carbs, cam, intake etc. The valve job was also untouched, seats were still nice. I did give the valves a quick clean up grind. I wanted everything to be as same as possible. That's one of MY expierences, so when I tell you that an aluminum Block doesn't lose power, it's not a theory. For those that lose power, I don't know what to tell you.

So, what is happening? Why does it want LESS fuel to make more power? I think the aggressive finish is peeling the fuel out if suspension, causing it to puddle. There for it needs more, to have enough that's atomized well enough to burn, to make that power. The smooth finish is not doing that, so it needs less to make more.
Last edited by Frankshaft on Wed Jul 11, 2018 7:33 pm, edited 2 times in total.
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Re: Iron to Aluminum block/Burr finish to smooth

Post by Frankshaft »

For shits and giggles, it was run with some sv1 carbs.
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Re: Iron to Aluminum block/Burr finish to smooth

Post by Frankshaft »

All the major details are the same. Decks set to same heights, same Pistons from the one into the other. So, compression is obviously the same. It was about as back to back as possible. The intake ports were slightly larger. But not radically.
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Re: Iron to Aluminum block/Burr finish to smooth

Post by GARY C »

I may be wrong but it seems the burr finish would be more likely to help a runner that's to big than one that is correct.

I didn't know that people thought an alum block would make less than iron, i'm pretty sure that's been debunked in regards to heads.
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Re: Iron to Aluminum block/Burr finish to smooth

Post by Frankshaft »

GARY C wrote: Wed Jul 11, 2018 9:12 pm I may be wrong but it seems the burr finish would be more likely to help a runner that's to big than one that is correct.

I didn't know that people thought an alum block would make less than iron, i'm pretty sure that's been debunked in regards to heads.
Did you not see the thread about aluminum blocks, you had to have. In theory, the Burr finish could have been hurting power 65hp. Since an aluminum Block kills 40 hp. It picked up 65, but lost 40 due to the aluminum Block, netting 25hp. Maybe.
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Re: Iron to Aluminum block/Burr finish to smooth

Post by treyrags »

Frankshaft wrote: Wed Jul 11, 2018 9:33 pm
GARY C wrote: Wed Jul 11, 2018 9:12 pm I may be wrong but it seems the burr finish would be more likely to help a runner that's to big than one that is correct.

I didn't know that people thought an alum block would make less than iron, i'm pretty sure that's been debunked in regards to heads.
Did you not see the thread about aluminum blocks, you had to have. In theory, the Burr finish could have been hurting power 65hp. Since an aluminum Block kills 40 hp. It picked up 65, but lost 40 due to the aluminum Block, netting 25hp. Maybe.
:lol:
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Re: Iron to Aluminum block/Burr finish to smooth

Post by Rick360 »

Thanks for posting some real tests with dyno data. =D>
Good info instead of all the parroting or advertising we are used to seeing.

Rick

ps: the sv1 test was surprising. :-k
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Re: Iron to Aluminum block/Burr finish to smooth

Post by houser45 »

Wouldnt the burr finish idea be more of a possibility on a port that has a possibility of being a poor at wet flow? I do know that a brodix 11x spec sprint head with a nozxle directly behind the valve moves the most air and makes the most power with a smooth finish. The block though, the stiffest cylinder walls win. I would agree on the iron block making more power,
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Re: Iron to Aluminum block/Burr finish to smooth

Post by grant6395 »

Rick360 wrote: Wed Jul 11, 2018 10:00 pm Thanks for posting some real tests with dyno data. =D>
Good info instead of all the parroting or advertising we are used to seeing.

Rick

ps: the sv1 test was surprising. :-k
I switched to a 115 mm sv1 from a book 1150 and picked up a solid 25 hp. I belive they work. This was on a 900 hp n/ a sbf. All across the board.
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Re: Iron to Aluminum block/Burr finish to smooth

Post by GARY C »

Frankshaft wrote: Wed Jul 11, 2018 9:33 pm
GARY C wrote: Wed Jul 11, 2018 9:12 pm I may be wrong but it seems the burr finish would be more likely to help a runner that's to big than one that is correct.

I didn't know that people thought an alum block would make less than iron, i'm pretty sure that's been debunked in regards to heads.
Did you not see the thread about aluminum blocks, you had to have. In theory, the Burr finish could have been hurting power 65hp. Since an aluminum Block kills 40 hp. It picked up 65, but lost 40 due to the aluminum Block, netting 25hp. Maybe.
I don't do my own machine work so I don't usually look at those threads, I leave all that up to my machinist so I can blame him if anything goes wrong. :)
I did just go look at the first page, I think there is probably a lot of belief held over from the early aluminum block issues, if I remember right aluminum heads were hated for years but now it's about all that anyone will run.

What made the most power gain is hard to say unless you did the port work after base lining with the new block build. Any portwork burr or 60 grit could effect the shape and size so I don't know that subject will ever be conclusive.

My guess is the gains are a combo of things, I'm thinking the structure of modern day alum blocks may provide a better ring seal and reduced windage considering that has been their focus.
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Re: Iron to Aluminum block/Burr finish to smooth

Post by Stan Weiss »

Have not done any dyno tests on this and so have no personal information.

I was told by someone who saw the dyno tests in the 70's using 2 BBC Pro Stock engines the iron block was 15 to 20 HP better than the Alum one.

Clearly a lot of information not show on the dyno sheets like A/F ratio, lb/hr, and dyno room weather for example.

At 7200 RPM there is no difference in BSFC and a 28.8 HP difference. So a WAG would be greater air fuel flow into the engine. Without seeing how much that was there is no way to guess about the block material on the outcome.

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Re: Iron to Aluminum block/Burr finish to smooth

Post by John Wallace »

Cool data!

It would have been nice to have seen the aluminum block dyno'd with the heads as before, then polished.
Is the cast iron block still available?
Maybe make a test with the polished head on the old block?

Definitely the combo works better now.

:)
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Re: Iron to Aluminum block/Burr finish to smooth

Post by Steve.k »

Frankshaft wrote: Wed Jul 11, 2018 7:17 pm I wasn't going to post this, it's my info, don't usually post results. In Lou of a bunch of threads relating to the thread title, this engine or engines I suppose, covers 2 subjects at once. The belief that the Burr finish is the end all be all, and that aluminum blocks make less power than an equivalent iron block engine. Well, this particular test,, was interesting, and the kind of stuff I am involved with on almost a daily or weekly basis, I have TONS of info like this, but most guys on here want to discount it, so, I say, to bad, I won't share. Oh well, why would I care, lol. It dawned on me this morning, about this test we did earlier in the year. 601 inch big block Ford it happens to be. Likely one of the highest horsepower Super Cobra Jet headed engines in the country. Engine was originally built with a Ford motosports iron block. Ford's equiivalent to a gm bowtie. Beefy, thick, strong, stable, etc. 4.5 inch stroke lunati crank, Oliver billet rods, 625 custom age bolts, custom Pistons, gas ports, .043/.043 3 mm rings, back cut top, Napier second, and low tension oil. Heads are the previously​mentioned Ford motosports Super Cobra Jet heads. 2.25 intake valve added, with my specific valve job. Engine has a dry sump, and a vacc pump. Intake is a rare Kasse cast tunnel ram. 2 small csu dominators. Sid roller cam, etc.

Engine is run A LOT. The car is a 3350+ pound mustang bracket car. It's​run every weekend somewhere. There is pictures of the heads on speedtalk, it was one of the finish threads. Not sure if it was Vizards, or Brad hs. I lost the pictures, they were in my crashed old phone. Those pictures show the aggressive cuttered finish. So, this past winter, we wanted to try a smooth finish. At the same time, they found a really good deal on an old good shape Allen Root aluminum block. 100% of the parts we're swapped over, after re machining Everything. Touched​up line hone, decks, cylinders were sized for the Pistons. Bores were 4.560 or something, made them 4.610. EVERY single piece was the same from the other Block. Except obviously fresh rings, bearings and gaskets. So, the only changes, smoothing the ports, 60 grit, from aggressive cuttered finish. To be fair, the ports were larger, as the aggressive finish needed to be ran over with a smoother carbide, to remove all the deep texture, and the Block. Went from iron, to the aluminum.
Very good lol. I rest my case!!
Last edited by Steve.k on Thu Jul 12, 2018 10:13 am, edited 1 time in total.
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Re: Iron to Aluminum block/Burr finish to smooth

Post by blykins »

Stan Weiss wrote: Thu Jul 12, 2018 1:21 am Have not done any dyno tests on this and so have no personal information.

I was told by someone who saw the dyno tests in the 70's using 2 BBC Pro Stock engines the iron block was 15 to 20 HP better than the Alum one.

Clearly a lot of information not show on the dyno sheets like A/F ratio, lb/hr, and dyno room weather for example.

At 7200 RPM there is no difference in BSFC and a 28.8 HP difference. So a WAG would be greater air fuel flow into the engine. Without seeing how much that was there is no way to guess about the block material on the outcome.

Stan
Bingo.

Frank, can you please take pictures of each dyno sheet individually, along with showing the weather data and uncorrected/corrected numbers?
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