New block source

[blykins]

I am a bit of a skeptic here on this argument.  If the water temperature is controlled with a good thermostat, radiator, and water pump, etc., then there should not be any moving around after the engine gets up to operating temperatures, and the ring seal should be stable, as well as power production.  That is where I have my doubts on losing a lot of power, if any.  I realize the aluminum grows, but it stabilizes, and if the clearances are all done correctly, then at operating temperature the output should be very close between the two engines if everything else is the exact same parts used, everything, down to everything but the block and rings.  Bore dimensions and hot piston clearance would have to be exact, or the looser piston to wall clearance would win regardless of which block is being tested.   Joe-JDC

Joe, hop over to Speedtalk and read some of the threads that I referenced. 

The difference between a cold block and a hot block is extensive, and obviously we don't hone with the blocks at operating temperature.  If lash grows by .015" when hot, cam bearings need to be pinned/Loctited in, and main clearances are adjusted with aluminum blocks, think about what is happening to the material behind the sleeve because of material expansion.  Aluminum can have almost 3X the heat expansion coefficient as cast iron. 

[1968galaxie]

There are several examples of aluminum blocks with thick walled steel liners - One example: Darton sleeves.
There is water jacket around the Darton sleeves - sleeves are located at top and bottom.
Interesting information: https://www.dartonsleeves.com/tech_ctr.html

Thin wall sleeved aluminum blocks certainly may distort and cause issues with ring sealing.
It depends on the total design.

Porsche 911 cylinders are aluminum allow with nickel based coated cylinder walls. These engines are dinosaurs by today's technology - but made incredible reliable power in NA and turbo applications for endurance racing - 24 hrs of Lemans and many other international racing organizations. Porsche 917 (Can -Am), 935's, 906, 908, etc... all used aluminum or magnesium blocks with Nikasil/aluminum cylinders.

[CaptCobrajet]

I'm going to have to chime in here.  Jay, I SERIOUSLY doubt that you have dynoed more FE engines over the last 25 years than I have.  There is merit to all of you fellers with engineering degrees.  I'm pretty good at complex math, and took some of your engineering classes when I needed electives to fill a category.  None of that can prove or disprove trends seen in results over a long period of time.  I'll go ahead and safely say that at this point, I have a PhD in FE Ford engines, given that folks obtain those fancy letters by educating themselves and proving there data.  I have made several thousands (no bull there) dyno pulls on FE engines, and I am 100% certain that iron will make more power, no matter what you do to try to adjust and compensate for the block expansion.  I think it might be 40 hp at the 1000 hp level.  I think it might be more like 20 at the 500 hp level.  I believe it is linear like that with everything else a constant.  The quality of the iron block is also a factor.  A paper thin OE sideoiler is not going to seal as well as a new, thick, siamesed BBM iron piece.  The Shelby is hands down the best aluminum block.  The BBM iron has given me the best numbers, so a comparison in my mind should include those two examples. I would add that the cylinders in the Pond aluminum blocks are very stable compared to the Shelby, and his newer blocks with heavier main webbing should be an equal to the Shelby.  I have some of these in process currently.

I believe that with more compression, it exacerbates the problem, and I believe with less compression it diminishes somewhat.  Most of these.....not all.....OE aluminium engines are lower compression, lower hp engines.  Most higher hp ones have turbos or superchargers that more than cancel the loss.  Many have vacuum pumps of some kind or another.

Dry sumps pulling crankcase vacuum and vacuum pumps on wet sump engines WILL definitely help.

Just like everyone else, these are my opinions based on years of data.  I have built the "same exact" engines, and my results are very repeatable.

[cjshaker]

I remember hearing over and over from multiple people how you can't run more than about 10:1 compression on pump gas, and yet I've run multiple Drag Weeks, 1000+ miles over the week with engines from 12:1 to 13:1, pump premium fuel.

As an aside, go put one of your 13:1 engines on the dyno and make a loaded pull with pump gas and report back.  

Jay, I can't believe you even made that statement. Did you ever race the car with premium pump gas? No, you switch to 110 or better octane. You, of all people, know that mild street driving is a FAR cry from wide open throttle racing.

Not trying to be an ass, but I think you're wrong about the "more than anyone on this forum" statement also. Comparing a hundred intakes on 2 or 3 engines (or whatever the count is) is certainly not the same as dynoing a hundred different engines, and certainly doesn't add any to your argument.

When every major performance engine builder, no matter the make, states the same thing, and they all do, I'd tend to believe them, regardless of my 'intuition'.

[cammerfe]

I have succeeded beyond my greatest imaginings in creating a thread that'll call forth the best thinking of this most excellent group. The comments here have been civilized, erudite, have come from different viewpoints and helped immensely in my quest for a clearer path in developing some of the aspects of my intended project.

One of the benefits of working with my intended manufacturing company is that they have the attitude that, "Of course we can". They have a very extensive background in doing performance versions of a wide variety of internal combustion engines. I believe that most of them are solid blocks with no water jackets. But I also know that it's a "Ho-Hum" for them to do what they call 'endurance' engines which DO have water jackets. Since it's my intention to actually use at least one of these engines on the street, (With the boost turned down to almost nothing, so as to simply assure 100% volumetric efficiency) I'll have to have enough water jacket to make this possible, but that can very likely be done on the outer sides of the block, with the scalloped cylinder surfaces receiving the coolant bath. The four-cam Jaguar-design engine in my ECTA car has water jackets that only extend down the cylinder sides to about the point of the bottom ring land with the piston at TDC. Most of the block solidly supports the sleeves, which are cast in place. Does this schematic suggest a degree of guidance? I think so, even with replaceable sleeves. A solid cam tunnel will also do well to offer rigidity.

When looking at power loss, the combination of variable boost, provided by the control system, and the ability to simply add more methanol as necessary will make getting the power level I need to get to my self-imposed speed goal a reality. Trying to go much richer using any sort of gasoline reaches a cut-off point at about 12.5/1. With methanol, the more you give the engine, right down to somewhere in the high 3/1 area, the more power you make. in fact, one must be careful because hydraulic lock is a distinct possibility if you aren't careful. In the end, I can overcome any power deficiency by simply 'tipping the can' a bit more or turning the 'horsepower knob' a bit and upping the boost.

There is also ample research that suggests using straight propylene glycol as a coolant. It has a superior ability to carry away heat, when compared to water or water/ethylene glycol as is usually used in cars. Propylene glycol does take a singular-design radiator and pump speed/capacity to match in order to make proper use of it.

Luckily, we aren't going to start to put the components together in the next few days. The final configuration will make use of all the truly learned I can get input from. I thank all of you for yours.

KS

[jayb]

Blair, I have records for 127 engines that I've dynoed on my dyno since I set it up in 2005.  Different engines, not just intake changes.  There's a few 385 engines in there, but the rest are FEs.  That doesn't count the 5 or 6 that I had dynoed prior to getting my own dyno.  I find it hard to believe that a guy who hasn't got a dyno in his own shop has done that many.  I would not claim to have built anywhere near as many engines as you, but I'd stack my dyno experience up against yours anytime.

And Doug, what makes you think I haven't gone down the track on pump gas?  I haven't done it with my SOHC cars, but the 511" FE in my Mach 1 Drag Week car has gone down the track on pump fuel.  It was only 12:1 of course, and on Drag Week I did run race gas.  But that engine ran fine on pump fuel, no matter the venue.  In fact, best pass ever on that car was a 10.45, on 92 octane 10% ethanol pump fuel.  I can't believe you made the statement that I haven't done that.  How would you know??

Sheesh 

[CaptCobrajet]

Wow Jay, 127 engines? That's about four years here.  There have been years, several years in a row, that we do thirty complete FEs in a year. Probably at least ten of the last twenty five years.  We dyno just about everything that leaves here, with few exceptions.  Thanks for all the kind words.  What you find hard to believe doesn't really matter to me.  I should have kept my trap shut.

[Autoholic]

I think it might be 40 hp at the 1000 hp level.  I think it might be more like 20 at the 500 hp level.  I believe it is linear like that with everything else a constant. 

The math on that, would mean an iron block makes 4% more power over an aluminum block. Considering aluminum expands more than iron when heated up, that could be a reasonable approximation. A tad more blow by due to aluminum having roughly twice the thermal expansion coefficient. A 4% difference in power when you're running carbs is somewhat negligible. It would be more noticeable on EFI builds. If you really wanted to prove this, don't just look at the dyno numbers. Connect a pressure gauge to a PCV system on two almost identical engines. Or maybe a MAF sensor would be better than a pressure gauge? I'm sure you all get the idea. If aluminum blocks make less power, it would be due to more blow by. This would eliminate the need to have identical spec engines, just two that are close enough.

My 0.00002 cents on the CR issue, the static CR is mostly meaningless when looking at pump gas or race gas, because that number doesn't take the cam or altitude or boost into account. It's the dynamic CR and dynamic cylinder pressures that will matter. I'm not nearly as experienced with engines as some of the guys on here, but I know the static CR is not what really matters. You could have a 10.5:1 CR but the wrong cam could turn that into a dynamic CR of 8.7. Similarly, you could have an 11:1 CR but wind up with a dynamic CR of 7.8. Heck, the static could be 9:1 but running a lot of boost could require race gas regardless of what even the dynamic CR shows. Even a little reading on dynamic CR will bring up roughly 8.5 is around the upper limit of pump gas, for N/A.

[Barry_R]

I suppose I should add my opinion into the ruckus....just because.

We have run a fair number of FE engines on dyno as well (seems like its between 40 and 50 customer engines each year, plus whatever personal stuff I have played with).  We have dome several that were fairly similar combinations in aluminum and iron.  Without chasing down examples I would say that most of the aluminum ones do come in a bit light compared to iron examples - maybe 3 to 5%.  Without OEM level testing equipment all I can do is to guess at the reasons.  There are likely a few candidates for the difference - bore integrity and deck clearance variation are the best bets. 

Bore variation would not be just the roundness (I bet a good quality and thick sleeve would hold diameter fairly well) but also the relative position of the sleeve in a block that will move quite a bit with heat.  A lot of OEM stuff uses really odd sleeve outside diameter contours so that they can be poured in place - little spines, knobs, and such are all used to maintain position.  Aluminum growth and movement was the motivation behind the adoption of MLS head gaskets and o-ring seals around the engine.  Growth will be non-linear, being greater in areas of larger mass - same situation that applies to pistons where they actually build up tilt into rig grooves to compensate for thermal growth variation.  Another impact item on power differential would be the additional +/-.008 in growth we measure based on lash variability - which would directly impact both quench and true operating compression ratio.  Compensation for both of these characteristics can be "built into the mix" when assembling.

One of the local machine shops specialized in highly developed oval track small blocks - dozens of functionally identical engines.  They are very tightly regulated as to the parts they can use, measured compression at cold engine temperatures, cam lift, carb, intake and several other items.  Although vehicle weight was specified, how they reached that target was fairly open and aluminum blocks were both legal and tempting because they allowed weight to be strategically relocated.  They said that they were about 20 horsepower off with the alloy block and they could not get an offsetting advantage that justified the move - they went back to iron.  This mirrors the behavior of a great number of professional race programs that go to CGI thin wall castings at great expense in order to get the weight savings and keep the power.  I believe that the difference is real, but depending on the combination it may be small compared to other variables, and could easily be buried in other gains or losses of greater magnitude.

On the pump gas side note - a very good head and a well refined package seems to be pretty darn forgiving on fuel.  The engine in my car is an old EMC piece that has compression over 11:1, and goes 7500 RPM with power numbers over 700.  I usually run race gas as a safety item and I like the way it smells.   .  But I have run it many times on local 93 octane and it seems to do just fine with no noticeable change in performance.

That dynamic stuff kinda scares me.  If you have a 12:1 compression engine, somewhere around torque peak you are going to have a 12:1 compression engine no matter what the DCR math is telling you.  If that engine has for example a
BT head with a heart shape chamber and a tight quench along with a flat or dish piston you will have reduced timing requirement and it'll probably be just fine.  If you have a big old dome piston and an old boot heel 427 chamber you might need 40 degrees to run right, and you might not be so fine...

[Autoholic]

That dynamic stuff kinda scares me.  If you have a 12:1 compression engine, somewhere around torque peak you are going to have a 12:1 compression engine no matter what the DCR math is telling you.

That's why you also need to consider a "boost" compression ratio, even on a naturally aspired engine because the VE could exceed 1 at peak torque, and definitely will on an engine built for performance.

[Rory428]

Chances are that I will never own an aluminum FE block, but my macinest/dyno owner buddy had a customer who brought in a new supposed "1000 HP" all aluminum 520 ish inch BB MoPar. On his dyno, it maxxed at 940 HP. After a couple years of racing, the owner had him freshen up the engine, using all the same components, but in a iron "Indy Max" block. No other changes, still didn`t hit 1000 HP, but did improve to 980.

[cjshaker]

And Doug, what makes you think I haven't gone down the track on pump gas?  I haven't done it with my SOHC cars, but the 511" FE in my Mach 1 Drag Week car has gone down the track on pump fuel.  It was only 12:1 of course, and on Drag Week I did run race gas.  But that engine ran fine on pump fuel, no matter the venue.  In fact, best pass ever on that car was a 10.45, on 92 octane 10% ethanol pump fuel.  I can't believe you made the statement that I haven't done that.  How would you know??

Sheesh 

I made an assumption and apparently I was wrong. But it seems stupid to buy race fuel for a car that obviously didn't need it, doesn't it? 

Mr. Kaase has built hundreds and hundreds (probably more like thousands) of "recipe" engines, as Brent calls them, over the years, and in several iterations. I'd venture to say that he has more experience with a single engine design than just about anyone alive. That means he has a tremendous amount of experience in the variances of subtle changes to that engine design, and especially in iron vs. aluminum in similar/same builds. That man is more open about engine building "secrets" than anyone alive, and has decades of experience to back it up. And that's all after his hugely successful racing career as an engine builder. He says the same thing about iron vs. aluminum. But what the hell does he know?

[WConley]

I've been out of the OEM world for quite awhile, so I don't have the magic answers on OEM aluminum blocks.

I will say that aluminum does move A LOT with temperature.  I did head gaskets for several years on iron block / aluminum head engines.  We'd tear down a test engine after 200 deep thermal cycles on the dyno, and the coating would be scrubbed right off the head gaskets.  The original 3.8L V6 was designed to be all-aluminum.  The blocks just would not stay together at sustained max torque though.  In some cases they literally fell in half on the dyno!  The desperation fix was to pour cast iron into the same block tooling.  Funny - Cadillac had the opposite problem with their Ht-4100 V8.  It was supposed to be all-aluminum, but they couldn't get the heads to stop cracking.  They ended up putting iron heads on the aluminum block.  I was around for the first 2V and 4V Modulars.  The early aluminum 4V engines had terrible cap walk issues- so much so that the cross-bolt jack screws would eat into the side skirts.  Goes to show that even the smart guys at the OEM's sometimes get it wrong.

The aluminum alloys have gotten a LOT better, as has the casting and block design technology.  OEM aluminum engines pass ridiculous emissions standards and provide excellent fuel economy.  They save weight and can be easier to cast / machine than iron blocks.  Many aluminum blocks are even die cast today .  Sometimes there are durability issues (reference the Fusion Sport thread in non-FE Discussion), but for the most part they run pretty well.

It's just not as easy to design aluminum engines.  As Barry alluded, you have to watch where you put material.  You're always chasing fatigue and thermal cracking / loss of heat treat.  It's harder to make the holes stay round and to keep fluids separated, but with enough work you get there.  It took 15 years for the Modular V8's to start getting really good.  Now you can make HP levels approaching ten times what the original designers envisioned!

[frnkeore]

If there is a difference in power output, between aluminum and cast iron blocks, it almost has to be because thermo differences, between the two.

First there is the cylinder head. I don't know if Blair's resulting differences are with cast iron or cast aluminum. I think everyone will agree that cast iron heads retain more heat, in the combustion chamber. Heat IS power. So, all things equal, the cast aluminum head, will loose more heat, just because it transfers heat faster. But, I know of no one, that is willing to give up there aluminum heads or intake, for that matter. Just those two items amount to over 100lb on a FE and acceleration amounts to Wt/HP. Hard to over look in anything but, maximum attainable speed, read LSR or dyno, read here EMC but, just HP, can't win a auto race if it can't be competitive with weight, also.

That's one type of thermo lose but, therm o-exspansion is another, increasing deck height and decreasing compression. The aluminum head, also grows at the same rate and remember, expansion causes growth, in ALL directions. The block and head both become longer and taller. alum to iron, by a rate of at least two to one.

The cast iron cylinder block and the cast iron cylinder liner, expand and loose heat, at the same rate, steel is also very close to that same rate. The aluminum block and head, looses heat at a faster rate but, you have some control over that.

So, let me suggest a couple of things.

1. Use long head studs, that anchor into the crank case and seal with a copper or gas filled O-ring. That gives the same basic expansion from the block to the bottom of the head, excluding the crank case area, with less expansion worries to the top of the head.

2. Locate the block to head with with four or five, 1/2" dowel pins. Seal the head to block, with o-rings (water transfer) and a flexible perimeter gasket.

With that arrangement and a machined 7075 block, you get at least 1.5 stronger and stiffer block. More than that, because the walls will be what ever thickness you want and a even section, w/o any problems that core shift would cause. As well as somewhere between 1/3 and 1/2 the weight of a cast iron block.

Another option would be to also, counter bore the head, to fit  over the cylinder liner, for added support.

[blykins]

Chances are that I will never own an aluminum FE block, but my macinest/dyno owner buddy had a customer who brought in a new supposed "1000 HP" all aluminum 520 ish inch BB MoPar. On his dyno, it maxxed at 940 HP. After a couple years of racing, the owner had him freshen up the engine, using all the same components, but in a iron "Indy Max" block. No other changes, still didn`t hit 1000 HP, but did improve to 980.

I've heard Darin Morgan speak of that as well.  The blocks seem to settle over frequent freshen-ups. 

On a separate note, I appreciate Blair and Barry speaking up.   I ain't never wrote no book or won an EMC, but every complete engine that has left here has been on a dyno, with zero exceptions.   I'm not a 50 engine per year guy, or even a 30 engine per year guy, but I would venture to say that even my little 1-man operation has put more than 127 engines on the dyno over the past 17 years.  I do have 2 engines on the island of Malta if that counts for anything.....   But across the different engine platforms that I have experience with, I have always noticed a dip in horsepower with aluminum blocks.  It is what it is. 

For some reason, this is a very sore subject and I don't understand why.  The data is there to back up the power loss statements, but every time I do make mention of it, people come at me like I just shot their dog.  I feel like the differences are substantial enough that it should play a role in choosing parts for a specific application.