[69Goat1]

Finally getting to the financial place in my life that I feel comfortable to build my dream engine/car. I have decided on the IA II aluminum block as my base and now I need to get the order in. My question is what should I add to the order as far as cam journal (stock, 50mm, or 55mm)? What bore size and stroke should I go for a healthy roots blown/nitrous engine (both at same time)? My goal is more than 1200 HP and on E-85 or 110 octane race fuel. Will be through twin dominator carbs and I will be running Eheads I already have. The car will be my green 69 GTO I used to race and hasn’t moved under its own power since 2012. I do all my playing in my other “street” 69 GTO, blown, nitrous...

[3fastgtos]

I personally would go with a 55 mm cam journal, 4.35 bore and 3.75-4.25 stroke. There are factors that would decide my stroke but the other two are for sure.
Just my .02,
SD

[mgarblik]

You will probably get lots of opinions, so I will throw one out your way. With the aluminum block, I like the smaller bore. I think you can easily meet your goal of 1200+ HP with a blower or nitrous with a 4.250 bore. That gives you an extra .100 sleeve thickness which will hold it's shape much better and give your head gaskets a better chance to seal. I like the 55MM cam tunnel. I see no reason to use a 50MM cam. I would leave it stock or go 55MM. The big cam gives you nice options for limiting the oil to the top with the cam bearing position. I would also have 1" lifter bushings installed and use a .903 lifter minimum, .937" if you like. I am a big fan of aluminum connecting rods. Less reciprocating weight and the shock absorbing nature of aluminum rods gives you a huge margin for error with your tune-up, especially if your going to run nitrous. They are also less expensive than a quality steel rod, like Carillo, Oliver, Manley, or Crower. Not comparing them to Chinese junk. Your engine deserves better than that crap. I have been happy with the 4.25" stroke we run in our aluminum block. That is the maximum stroke I could recommend. Depending on your specific goals, a shorter stroke could be a better choice. I think you will really like your aluminum IA II. Put the best parts inside you can afford, and it will be an excellent engine.

[Dragncar]

Talked to Frank about the IA2A. He said 55mm is the way to go. More options for making power for the cam grinder. And he said the valve springs last twice as long.
Blown aluminum IA2A, I would go 4.32 or less. You could go 4.35 like so many do. But you are boosted and the added wall thickness could not hurt. Also if you go 4.35 you only have a VERY max bore of 4.38. heck, the KRE aluminum block has a max bore of only 4.35.
The Boss Bird fellas did give me a nice suggestion if I went 4.35. And the ONLY reason I am thinking about it is I already have some 4.35 pistons. It was past 4.35 in case you hurt a cylinder for whatever reason is to treat each hole like a single cylinder engine. There are a couple ring sizes in-between 4.35and 4.38. Its no big deal to get custom pistons for several cylinders and keep the rest @ 4.35. The engine does not know the difference and you save that precious cylinder wall.
But buying a IA2A and only having one full bore size is kind of hard to take. A iron IA2 and you get 3 full bores starting at 4.35.
Verdi is the guy to talk to about IA2A blocks, he has 3 of them. When I called him up, very nice guy. The jist of the conversation was the IA2As have gotten better each time. First one needed a bunch of work to get ready, next one less. Final one needed very little work, great piece.
Sure aluminum rods do give you some forgiveness. But when I spoke to Tom Molnar about his Power Adder rod the results he gave me was they have been run on 2000HP NO2 632 BBCs and the rod bearings came back perfect. While originating in China they are fully machined here and the cross section when compared to a Eagle or Scat is not even close. And they are less than 800 $, hard to beat.

[AG]

I went with a 4.320" bore and an Ohio 4.21" 4340 crank with my Ali. Plenty of meat for multiple bores, since you can go 0.005-0.010" bigger at a time, but hopefully won't need to since it will be street/strip. Crower rods and Ross pistons with SD 335 cfm CNC chamber heads, wish I went next size on the heads in hindsight.

[mgarblik]

No personal experience with Molnar connecting rods. However, based on the history of the man who owns the company, looking at the parts in person, rods and crankshafts, I would feel OK giving them a try. It's not where the rods are made specifically that's the problem. If the quality of the raw material. the forging dies, the mechanical process of making them is all closely controlled by people who understand the eventual use of the product, they are probably fine. The Molnar products seem to have control through the entire process. Others on this board are happy with them, but not sure what their HP and RPM level are. A quality aluminum forged rod, like a BME, just gives that extra margin of safety and cushion if the blower or nitrous tune isn't spot on. I have never been comfortable with a 1200 + HP tune up out of the box to take that chance. With nirtous, if your timing is off 2 degrees, you may have an oil pan full of aluminum cole slaw, rather than just some aluminum rods that just need to be resized. If I was going to run NA with big HP and high RPM, I would give quality steel rods a serious look. Cost for a set of BME rods is not much more than the Molnar steel and half the cost of Carillo. It's going to come down to a personal preference. You may want to take a look at the bmeltd.com web site for some technical information. I can say that we did allot of really stupid things with the Grocery Getter over a 17 year period, mostly by honest mistake, and never lost a connecting rod or connecting rod bearing. That says allot.

[GTOGEORGE]

From experience I would go with a small bore (less then 4.32) for head sealing and aluminum rods. I’ve run steel rods and my bearing looked much better with aluminum rods using forced induction!



GTO George

[Hooter]

Molnar crank and rods in my 521. Only 780hp, but no issues. Chose Molnar for the reasons Mike mentioned.

[PAUL K]

4.25x4.25.....aluminum rods offer a lot of advantages on a power adder build. The 55mm will be better and offer room to grow.

[grandville455]

I went with a cast IA2, 4.350 Bore and my same 4.25 scat crank and callies rods in this new build, along with a 55 mm tunnel and .904 lifters

[69Goat1]

All great info and exactly what I am looking for. Thinking maybe a 4.25 x 4.25 or stroke it to 4.375 x 4.25 bore...right now we are figuring out our tax burden for the year and once I know what we owe I will know what I have to spend...

[69Goat1]

I also like the 55mm journal, 904 lifter, and aluminum rod suggestions. I really don’t have anything to start with for that kind of stuff other than the engine in my other GTO that I am not taking apart for this deal. Pretty excited about doing this...been a lot of years since I have been racing...

[69Goat1]

Block on the way next week thanks to Frank at allpontiac. Nice hunk of aluminum for a good foundation!