I need help with putting a rotating assembly together. Here is what I know at this point.
Running a dart little M block 350 or 400 mains?
Eagle forged crank what size 3.48 or 3.75?
Eagle h beam rods what size 5.7 5.85 6.0?
The heads will be either brodix T1 67cc or AFR 210 76cc head.I would like to run a JE off the shelf piston want 8:5:1 compresion.
This will be going witha pair of T4 turbos sc-61 from precsion. I want a motor that will be more built fore longevity then built to get every HP out of it. I also want a piston I can buy of the shelf not a custom built piston. Cubic inches should be 2nd to the most reliable cubic inch size motor.
So basicaly what size little M block?what Rod size? and what size crank? and lastly the AFR 210 76cc head will probably make the piston choice more practical in getting a of the shelf piston anf 8:5:1 compresion
I'am in the process of building my new 1 3/4 headers

 

I am getting parts together to build a blown 357 cubic inch LT1. It is going to be similar to what you are wanting to do. I have a bare LT1 block that I am going to have converted to 4 bolt splayed, bored .30 over, decked, line honed and heat tanked. I am going to stud the mains and heads with ARP studs and use a Milodon pan. I just bought a Cola 4340 Forged non-twist crank that is 3.50 inch stroke and one piece rear main seal. I am going to use Manley 5.7 inch H beam rods and JE's Extreme Duty -22cc inverted dome blower piston with Hellfire rings. I have bought some new bare AFR LT4 210 CC heads that I am going to have ported probably by AI. I am going to use either Manley or Ferrea valves and have AI do the complete assembly and flow the heads so they can custom grind a hyd roller for me. I am also planning on using a AFR rev kit and Cometic head gaskets. I of course have to use a LT4 intake that I am going to have opened for a monoblade and the runners welded and ported.

The AFR 210 bare heads come with 74 CC chambers so once they are ported, they may be up around 76 CC. With the pistons that I have chosen, the Compression ratio will be about 7.8 to 1 so it should be able to handle the boost pretty well. I want to build the engine to handle more boost than I am going to throw at it so that I hopefully won't have to worry about it. I am wanting to run a D1SC with about 15-20#'s of boost and go the custom FMIC route. I am shooting for around 650RWHP, but we'll see. Check JE's site, they have their Extreme Duty Blower piston that should suit your needs and I am pretty sure that they are a "off the shelf" item. I talked to JE about the Hellfire rings, and they are selling them as kits with their pistons now as an option. If you are going with twin turbo's, you might want to think about the Hellfire rings also, I see it as cheap insurance. Their site also has good data as far as choosing pistons/head combos with compression charts.

I am going with the 5.7 inch rod. I don't know, I was told that if your are doing a blower motor, that a shorter rod is better and that it also has to do with the location of the wrist pin on a piston for a 5.7 rod compared to a piston for a 6.0 rod. I have heard that the piston for the shorter rod is stronger, I don't know? I just talked to the guys at Cola and told them what I was building and that is what they suggested because I was going to use a 6.0 inch rod also. I also Spoke with Eagle's tech department and was going to buy one of their complete rotating assemblies, so I am modeling mine (spec wise) after the combo I found in their catalog. I went with Cola becasue I felt that it is a better crank than Eagle and I did not know that Eagle's are not made in the USA.

I don't know anything about the Dart blocks, maybe some of the other guys can help. I am going to get all of the parts together and probably let APE build the long block for me and do all the machine work. Good luck

 

I used a Eagle 3.48 stroke crank and 5.7 inch H-beam rods also with 2 precision SC-61 turbos. I chose the .69 A/R turbine housings, and they really love the new stall converter. spool is fast! and almost immediate with the pedal stomped.

 

Why did you choose 9:6:1 seems a little high? It looks like a shorter rod is better for boost for durability.
I have been watching your setup smoknz very nice setup, hows that thing on the street? What kind od HP numbers are you looking to get out of your setup? Those turbos should suport almost 1400hp
I chose to go with the little M since I would need to get a 70s 4bolt and after all the maching its not such a huge jump to get a little m. All the machine guys say that block is dynamite 1000hp is nothing for that block and so that will decrease the odds of engine failure.

 

I didn't choose 9.6, that is just the way it worked out. I decked the block and also had to have the heads milled to make them flat after I blew 2 head gaskets, all of which made the comp ratio kinda high. I'd really like to get some 78cc AFR's on the car. The car has some issues right now, I've only put about 500 miles on it, and that will probably be it for this year. It's pretty fun to drive when it runs! only at 7 psi though for now, gotta get an impedance converter for my 83# injectors.

 

Give us a call, that sounds like a pretty good engine you got going together. We would be more than happy to get assembled.

Thanks

 

IMO 7.8:1 is bit on the low side for a driver. off boost driveability will be sluggish.

Friend of mine has a Little M block in his 87 formula,.030 over,Cola crank,Eagle 5.7" rods,JE dished pistons,AFR 210 heads,solid roller. Compression is 9.2:1 and it will take all the boost we can throw at it. Right now it has a F1R Procharger,running 18 psi and it also has a spearco air/water IC. This winter we are going to pulley it up to around 24-26 psi and really start using the blower.
The crank/rods/pistons have been in 3 different blocks,and have spec'd out fine everytime. currently the car is making in the area of 800ish rwhp and will run on pump gas for cruising

 

I was thinking that 7.8 was going to be too low and I was worried about the driveability issues but I had a post going were some guys were saying that it would not be a problem at all, so I don't know. I think I am going to have to call an engine builder and find out for sure.