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 Post subject: 351c alm blocks?
PostPosted: Thu Mar 29, 2018 2:43 pm 
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Joined: Tue Jun 02, 2015 2:28 pm
Posts: 216
The mud truck crew want a new 351c block and save some pounds up front....And maybe more cid.(427?)
After the past weekends big blow it needs something better..

Apx. 5000.00$ budget and have it in 2-3 weeks.

Not really shore what's out there with the most bang for the buck??

Or least BIG BANG

This has been discussed in the past but running threw thread after thread to find it. takes time...


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 Post subject: Re: 351c alm blocks?
PostPosted: Thu Mar 29, 2018 2:53 pm 
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IMO, aluminum blocks are a waste of money.

Get them a Dart SHP block, change the timing cover and oil pan, and be a couple grand ahead.

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 Post subject: Re: 351c alm blocks?
PostPosted: Thu Mar 29, 2018 4:18 pm 
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Posts: 7
Dear Mr. Lykins,

You would seem to speak blasphemy against the conventional wisdom. Aluminum blocks have their advantages and disadvantages, I am told. Why do believe that an aluminum Cleveland block would be inferior to an iron block?


Curious, C. Engles


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 Post subject: Re: 351c alm blocks?
PostPosted: Thu Mar 29, 2018 4:29 pm 
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This seems to be the hot topic across two or three forms right now. The Cliff’s Notes version of it is that aluminum blocks are flimsy. They lose a good amount of horsepower to ring seal because the blocks are just not rigid enough to support the cylinders thoroughly. For whatever you gain in weight loss you lose back in horse power. So you end up spending $5000-$6000 for basically nothing. The only true advantage to an aluminum block is that they are easily repairable if you scatter your engine.

This is something that most engine builders know in the backs of their minds. However the appeal to most people to have an “all aluminum” engine kind of sets the tone for most builds.

There have been quite a few back to back tests on the dyno from several reputable builders that show a 25 to 40 horse power loss between exactly identical combinations except for the material of the block. It is thoroughly documented that you will lose horse power to an aluminum block.

I have several other reputable sources who will validate what I’ve been saying. Barry Rabotnick is one, Blair Patrick is another, and Lance from Craft engines is yet another. I have also heard Robert Pond talk about this on a couple of occasions.

I have also seen evidence of this from my own builds. I have torn down several all aluminum FE engines to find shadows in the cylinders, like the cylinders had not been honed with plates. But they had… This once again proves to me that the blocks move around way too much under loads. I have also seen oil usage in some all aluminum engines, along with some leaks from gaskets that typically don’t leak on iron block engines.

In addition to all of this, aluminum blocks carry more risk. They are more prone to porosity and pains have to be taken with pressure testing to make sure the blocks will not leak water when hot. Bearing clearances also have to be changed as aluminum grows so much with heat that the main bearing clearances will open up. Sleeves also have to be set before machining.

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 Post subject: Re: 351c alm blocks?
PostPosted: Thu Mar 29, 2018 5:51 pm 
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Joined: Mon Oct 23, 2017 9:53 am
Posts: 177
Ray your best bet is a 400 ford for mud racing in terms of cost. All the same usuable parts basically and better rod angles with the 400 style rod. As far as alloy goes,its weight you lose makes up any losses in heat transfer losses in engine hp. Im thinking theres a reason sonny's, jon kaase,Caroll Carter to name a few use alloy with great success!


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 Post subject: Re: 351c alm blocks?
PostPosted: Thu Mar 29, 2018 8:49 pm 
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When hp gets real high and the chance of exploding one is higher, then an aluminum block will help there because they are easier to weld up.

Weight doesn’t do squat for you if you’re losing equal amounts of hp to ring seal, and if your weight loss is equal to the hp loss, then you just wasted about $4000.

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 Post subject: Re: 351c alm blocks?
PostPosted: Thu Mar 29, 2018 9:03 pm 
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Joined: Wed Oct 31, 2012 8:43 pm
Posts: 297
I have to agree with Steve. I am going to start building an aluminum TrackBoss. I believe at one time there was a big difference between cast and aluminum blocks in regards to hp loss and rigidity, but now with super alloys and liners, and manufacturing process the difference is negligible. Here is how I feel, If I can achieve my goal of 900hp, and it losses 20hp, and makes 880hp, big whip. That is more than I will ever need. I am not going to go back and forth trying to have people agree with me or prove I'm right, I could careless. Brent like's iron, Steve likes Aluminum and prob iron too, like me. I want to get another motor together, where I don't have worry about oiling or block strength. I am going with the centralign rods too, there is an issue cause I heard some piston manufactures, adjust for this. Plus it is something that I always wanted, then when CGI get done, make my pro stock TR motor......DragBoss

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 Post subject: Re: 351c alm blocks?
PostPosted: Thu Mar 29, 2018 9:19 pm 
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I think engine builders see things quite differently than the end users.

Most of these aluminum blocks that are being cast now all have the same technology and material. One designer/foundry isn’t using unobtanium while another is using pot metal.

The horsepower testing between the iron/aluminum blocks that was done (A/B testing) at Craft Racing used both Shelby and Pond FE blocks. The Pond block was designed by Tod Buttermore. The Pond blocks are the ones I saw shadows in the cylinders as well. There’s only so many ways to design a block....

The only aluminum block that I would consider using would be a solid billet block with no water going through it. That would give the most rigidity and strength.

The CGI block would be the bees knees......but the cast iron Track Boss would be the most cost effective and would be the one I would choose for a customer who wanted a drag race engine. What you get for the extra $4000 just isn’t worth it. I know some of you all have deep pockets, but man...........

From Barry Rabotnick...


"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."

We may disagree but I still love you all. :-)

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 Post subject: Re: 351c alm blocks?
PostPosted: Thu Mar 29, 2018 11:55 pm 
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I would like to know how a fuel motor can withstand 10,000 hp with alloy but if you build that exact same motor to 800 hp the iron block makes more.The early pond/Buttermore blocks are old school and not the best casting. All the mainstream mfgs are going to alloy. The ford shelby mustang went to full alloy and brought hp up to 660 quite a bit higher than the 500hp iron motor it started out. The latter motor boosted to 1000hp by Shelby's crew as aftermarket mods took over. The 660 hp motor quite capable of racking up 100,000's of miles. So bottom line is depending on the build and strength of blocks I'd say minimal difference. Heads have been alloy for years and now are the heads of choice.


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 Post subject: Re: 351c alm blocks?
PostPosted: Fri Mar 30, 2018 6:26 am 
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Withstanding horsepower and making more horsepower are two different things.

Top Fuel cars use aluminum blocks because at 10000 hp, it's easier to be able to drop in sleeves between races, or weld a patch on a block, than worry about the horsepower differences. A 100 hp (or even a 250 hp) bump to them is nothing and could probably be caused by something extremely insignificant to the average guy. Not sure what your argument is there.

I've built more all-aluminum SBF's and FE's than probably anyone on this forum. It actually got to the point where I quit taking orders for aluminum block engines. The amount of liability on the builder's part goes up and the amount of labor/prep goes way up. Setting sleeves (even had one drop after it was set on the dyno, which resulted in having to tear that engine completely down, fix it, re-assemble), dealing with porosity (I've had 2 blocks that needed to go back to the manufacturer because they were porous between a lifter bore and a water jacket), adjusting bearing clearances to offset the material differences (main bearing clearances will grow about .00075-.001" when the block gets hot, so you set the cold main bearing clearances much tighter than usual), having the blocks sealed inside (either before with an aluminum sealant, or after the fact with something like Moroso Ceramic Seal), etc. are all parts of building and owning an all-aluminum engine. You can't just machine and assemble one like a regular cast iron block.

I'll also throw this in there since you mentioned the factory OEM stuff: Ford, Chevy, and all the other brands have a tremendous R&D budget. Tremendous. Simply put, the guys having 50-100 blocks cast a year do not.

Take note.....I didn't say that aluminum blocks wouldn't last. I didn't say that they wouldn't make horsepower. I'm just saying, emotional feelings aside, the data and facts are there: cast iron blocks on identical builds make more horsepower. Call Lance at Craft Racing and ask him about it. These were dyno results from last year, so the blocks were not "early". The issues that I've had/seen with aluminum FE blocks were not early blocks either....we're talking about 2017 blocks. Losing 40 horsepower off of a 750 hp build is TREMENDOUS!

Again, it's just my viewpoint and opinion as an engine builder, but I'm not sure why anyone would want to pay over $4000 more for an aluminum block. The cost efficiency just isn't there. And before you say that I'm dogging the Track Boss block, I'm not even thinking about Tim's stuff. The Dart aluminum 351W block is over $6200!!!!! Their SHP block is only $2038. Even if the weight savings did overcome the loss of horsepower, is it really worth an extra $4000? I guess if you're in the habit of windowing blocks, it would probably pay off..... :lol:

I'm not going to make this another "Centralign" rod argument here on the forum. I've stated my opinion, backed with data, and you guys are welcome to take what you want from it.

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