Shelby standard block question

[plovett]

Can the power loss with an aluminum block be minimized with thicker sleeves?  Just wondering.

paulie

[blykins]

Depends on the block and how strong the block is behind the sleeves.   The fact that the aluminum moves so much with heat doesn't help. 

Here's a couple of quotes that I dug up from a conversation that we had about aluminum FE blocks on Club Cobra:

This one is a quote from Dave Shoe where he had interviewed Robert Pond:

"The horsepower differences between iron and aluminum blocks have been repeatedly characterized by Robert Pond, though I am necessarily distorting his claims because I lack sufficient experience to fully comprehend all his findings. He has been particularly interested in horsepower gains as small as a single horsepower, as his Stock Eliminator racing engines are constrained in the modifications which are allowed. I've spoken to Robert a little bit about "free horsepower", and he strongly contends that the block, all by itself, can provide dozens of free horsepower between the 600 to 1000 horsepower levels, just by its cylinder rigidity characteristics."

And from Barry Rabotnick from his F-M days....

"Well - - I can add a little fuel to the fire.  I supply rings and bearings to a large percentage of Pro Stock, Cup, and fastest street car competitors. In virtually 100% of situations where the weight is not critical (meaning that they would have to add ballast to offset any weight benefit from aluminum to meet a mandated minimum) these competitors ALL run an iron block of some sort.

Iron blocks simply make more power. Every time. The commonly bandied about number is somewhere between 15 and 30 - depending on the power level and the particular engine in question. Big beefy billet caps on aluminum blocks are kinda like a super strong steel lid on a cardboard box - when they're stronger than the parent material the value is limited. Ultimate power handling potential is not an issue - both materials have been proven at levels beyond anything feasable in an FE (I have seen numbers near 3000HP).

When properly prepped and designed, neither material will show bearing issues - but aluminum does require tighter cold clearances. Fuel motors don't count - - repairability is more important than the nominal power difference when you're at that level. The sole benefits to an aluminum block are identical to those of aluminum heads - weight ease of modification and repairability."

[scott foxwell]

I think Blair has back to back between cast iron and aluminum builds.  I think Robert Pond has data too.  It's not a theory, it's something that's talked about quite often.

I prefer the cast iron because I don't have trouble with them.  Yes, they're easier to machine and take less assembly time, but as I mentioned earlier, I've experienced a good bit of down time and loss of profit because of aluminum blocks.  I'm a one-man shop and having to pull an engine off the dyno, disassemble it, cut the decks, buy all new gaskets, etc., then reassemble is a good chunk of time that's taken away from other builds.

The chances of problems go up with the quantity of blocks used.  I've used a lot more than 5 aluminum blocks and didn't have any trouble with the first few, but there's a bell curve to any statistical sample.   Keith Craft and I had quite a few discussions about this when he was building.  He had quite a few blocks that didn't pass the pressure test as well, and a lot of his blocks ended up with lifter bore bushings.  I sent mine back. 

I've had troubles with all aftermarket FE blocks, cast iron and aluminum, but I've had more trouble with aluminum blocks by far.   

The fact that I can almost buy 2 new cast iron blocks for the price of 1 aluminum is the nail in the coffin.

My first Shelby block was a disaster. 'Course, it was one of the first ones. The bores in the block were nice and round...the sleeves were nice and round, but put the sleeves in the block and everything when haywire, and I mean by .002-3". I looked at every possible reason...in the end, Mike LeFevers fixed it for me..along with the main studs that pulled out of the block when I torqued them. 
Water blocks are obviously going to be the worst, but when I was at Alan Johnsons, we always used gapless rings, even in the solid blocks like the KB or Rodack because of the fact that the cylinders are always moving around. Aluminum blocks are about the only place I use gapless rings, but ALWAYS in alum.

[Nightmist66]

Water blocks are obviously going to be the worst, but when I was at Alan Johnsons, we always used gapless rings, even in the solid blocks like the KB or Rodack because of the fact that the cylinders are always moving around. Aluminum blocks are about the only place I use gapless rings, but ALWAYS in alum.

Gapless rings can benefit in an engine running on alcohol, to keep from diluting the oil.

[fekbmax]

So with all thats been said,
Opinions on whats a better choice?
Assuming both are properly prepared and machined.
A nicely repaired pond aluminum block or a good factory cross bolt block with pro gram caps and properly applied block fill for 850 to 900 Hp.

[jayb]

I wouldn't run the Pond aluminum block that high, Keith.  As mentioned previously the main webbing on the Pond aluminum block is the same as their cast iron block.  It needs to be thicker.  I would have no issues with a Shelby block at those power levels (been there, done that), but I'd worry about the Pond block.  A filled iron block would be better, I think.

[Leny Mason]

Hi, Nick Arias said his aluminum blocks need to be run till they burn to much oil three times before the blocks stop moving around, on his by the time you put the third set of sleeves in it it will stop using oil, now that is in a speed boat it may be different  because of the water temperature is cool all the time, that is his story. Leny Mason

[stangbuilder]

   I will chime in here..I have a all alum fe in a resto mod mustang that i have been running for about 12 years and appox 50.000 miles..It has been blown up 1 time dropped a valve.  And rebuilt two other times because it burned oil..As we speak car uses about a qt every 400mi..I have tried every thing i know to fix it.different rings.honing ect ect..So at this point on this engine it been driven for appox 20.000 mi runs perfect hauls ass
 i just add oil..believe me i hate it..I have pretty much given up trying to fix it.

 stats on car 67 F/B shelby gt 500 car weights 3100 w/o me in it 477in all alum fe
 blairs pro ports and victor with fast xfi sportsman EFI
 Mike jones S/F/T Cam tremic 5 speed close ratio
 
  Know what people are thinking crappy mach work last machine shop that did my motor was shaver specialties in torrance calif..At the time i felt if anybody know anything about working with allum blocks he would ..

[BH107]

Lance Smith down at Craft Performance did a back to back test with Pond blocks. First one was 711hp cast iron. All of the components were swapped into an aluminum block and it was down almost 40hp.

[blykins]

Y'all keep talking, just makes me hate 'em more.......LOL

[Posi67]

Lance Smith down at Craft Performance did a back to back test with Pond blocks. First one was 711hp cast iron. All of the components were swapped into an aluminum block and it was down almost 40hp.

The fix is easy... I have a goal of let's say 750 HP in an Aluminum BBM block. I don't care if the Iron would make more so I'll just toss enough parts at the Aluminum to reach my target. If I decide at some point I need more HP then an Iron block upgrade is an option. 100# off the front of my car is appealing.

[blykins]

Lance Smith down at Craft Performance did a back to back test with Pond blocks. First one was 711hp cast iron. All of the components were swapped into an aluminum block and it was down almost 40hp.

The fix is easy... I have a goal of let's say 750 HP in an Aluminum BBM block. I don't care if the Iron would make more so I'll just toss enough parts at the Aluminum to reach my target. If I decide at some point I need more HP then an Iron block upgrade is an option. 100# off the front of my car is appealing.

Spend $5k for an aluminum block, pay more for prep, and make 750 hp......or spend $3500 for an iron block and make 800 hp. 

Numbers are theoretical for the sake of argument, but the points are still valid.  LOL

[Joe-JDC]

Y'all keep talking, just makes me hate 'em more.......LOL

Something doesn't sound right with this whole argument.  If what some of you are claiming is true, no new car manufacturer would build an engine with aluminum block and heads.  I know they are on a weight savings mandate to improve fuel mileage, but the easiest way to improve fuel mileage is compression, and good fuel.  Also, if Lance Smith did R&R the internals from an iron block and install them in an aluminum block, did he blueprint the aluminum block just a carefully as the iron block, did he use new rings, bearings, did he heat the oil, water, engine cycles to the same amount before testing?  Did he do this on the same day? Weather the same, barometer the same?  Etc., etc., I have to say that with all my years of experience, automotive degree, teaching experience, have I ever heard such an argument that cannot be substantiated with back to back dyno testing in a laboratory environment to eliminate all differences but the material used in the block.  A simple gasket mismatch in the intake tract can change the horsepower level on a highly tuned engine, and I have seen 20 hp difference back to back with that situation on the dyno.  I have also seen 20 hp difference with spacers turned around differently, or different timing, fuel pressures, different oil level in oil pan, all make differences in back to back horsepower testing to find the ultimate combination.  A carburetor not opening fully and not caught when installing on the dyno.  I have to call this an argument that I cannot agree with until I see it performed under the same testing environment on the same day with identically prepared engines, and have all the same pulls to break in, all the same temperatures, and same individuals monitoring the testing procedures to verify.  JMO, but skeptical to say the least at 20-40hp level.  Joe-JDC

[blykins]

I understand your concerns on keeping everything consistent, Joe, but the horsepower difference has been well documented by many others besides Lance Smith. 

As far as what's used in the OEM, they have millions and millions of dollars invested in research and testing, and produce literally millions of blocks on high levels of quality standards.   The FE aftermarket doesn't have any of that.  Actually, none of it.  I couldn't even get 5 aluminum FE blocks in a row that didn't have issues. 

On another note, just because it's used in the OEM doesn't mean it's right.  If you want to look at how flimsy OEM aluminum can be, take a Teksid 4.6 modular block and see if you can turn the crankshaft until all the main caps are torqued.   However, I would imagine that you had a good point about weight savings, fuel economy, and the EPA.....

[BH107]

Y'all keep talking, just makes me hate 'em more.......LOL

Something doesn't sound right with this whole argument.  If what some of you are claiming is true, no new car manufacturer would build an engine with aluminum block and heads.  I know they are on a weight savings mandate to improve fuel mileage, but the easiest way to improve fuel mileage is compression, and good fuel.  Also, if Lance Smith did R&R the internals from an iron block and install them in an aluminum block, did he blueprint the aluminum block just a carefully as the iron block, did he use new rings, bearings, did he heat the oil, water, engine cycles to the same amount before testing?  Did he do this on the same day? Weather the same, barometer the same?  Etc., etc., I have to say that with all my years of experience, automotive degree, teaching experience, have I ever heard such an argument that cannot be substantiated with back to back dyno testing in a laboratory environment to eliminate all differences but the material used in the block.  A simple gasket mismatch in the intake tract can change the horsepower level on a highly tuned engine, and I have seen 20 hp difference back to back with that situation on the dyno.  I have also seen 20 hp difference with spacers turned around differently, or different timing, fuel pressures, different oil level in oil pan, all make differences in back to back horsepower testing to find the ultimate combination.  A carburetor not opening fully and not caught when installing on the dyno.  I have to call this an argument that I cannot agree with until I see it performed under the same testing environment on the same day with identically prepared engines, and have all the same pulls to break in, all the same temperatures, and same individuals monitoring the testing procedures to verify.  JMO, but skeptical to say the least at 20-40hp level.  Joe-JDC

This wasn’t just something mentioned in passing, it was something Lance actually advertised with dyno sheets.

“We often have people ask what the horsepower difference is between cast iron and aluminum blocks. It often depends on the engine specs, but here is one that we ran on the dyno in a cast iron Pond block then swapped everything to a Pond aluminum. This is a 482ci, 11.5:1 comp, Stage III Edelbrock heads, and a street solid roller camshaft. Torque was basically the same but hp definitely dropped off on the aluminum. Back to back dyno play is always fun. — at Craft Performance Engines LLC.”

“I think there are several factors. Heat rejection being one, unlike cylinder heads, in a cylinder heat is power. The aluminum will distort more than cast iron under load and rpm, distorted cylinders = ring seal loss.  I believe this is the 4th back to back we have done and they are normally 25-40 hp difference depending on engine specs.”