I've got a question about 400" gm block durability, and what needs to be done to them to take pretty big power reliably.

The reason is the race series rules don't allow aftermarket blocks. I'd be taking all the internals out of the Iron Eagle and going back with a stock block.

BRC crank, carrillo rods, 4.130 ross pistons..

it's got a 101mm turbo breathing down it's neck, so it's got to be pretty tough..

or if it isn't a good idea and won't be reliable, let me know.

thanks!

 

the odds are not in your favor.
even with 50% fill, and front / rear motorplates you still have limited webbing and hardly any deck to deal with. not to forget pretty thin thrust on the cylinders.

In a perfect world, with no detonation, not torsional stress, and the perfect load....it may live forever.

In the real world...the odds are stacked against you.

My thoughts...call brezinski and have them "retrofit" an iron eagle to look like a GM 400

Dennis

 

I like the brezinski idea.... or do the same thing to a Bowtie block. Either way if the class allows you to put all these parts on it and not run a good block it's a stupid class in the first place.... the idea is to save money by not allowing aftermarket blocks, it's actually going to cost people more money to run this class since they will break more parts pushing the limit.

Bret

 

I wouldn't call it a stupid class, IMO. Similar to a class with a tire/wheelie bar restriction. Makes it pretty interesting for the fans, but pretty expensive for the racer.

Ryan

 

Thanks Dennis, Bret- are you saying it's a waste of time too?

How much power can you make reliably (and don't go saying BigRick this and BigRick that), on a stock block (non-LT1)? We might back the power down to make it live with a stock block..

Here are the rules: http://www.bahraindragracingclub.com/rules.html
The class is #6, Super Street The rules are a little odd, but what do I care

 

One of our dirt track IMCA racers is limited to an original block...we make 510rwhp and every two to three seasons the main-webbings start to break...all the other guys have stepped up classes so we can throw bowtie blocks in there.

I dont see where they say an aftermarket block is against the rules...am I missing it?

 

line #10 is interpreted as to allow any SBC original casting. The intent of the rule is "no aftermarket blocks and no crossbreeding".

 

I'd pull a Smokey Yunick and run the Dart since you have it..... unless the rules specifically say "YOU CAN"T Run a DART, WORLD or Bowtie block" I would run one of them. The Bowtie is a GM Casting so it's legal IMHO.

Bret

 

I have always "heard" that the 400 block weren't that strong. But I have no direct experience with them either.

And about the title, how much can a GMPP crank hold like the one you had in the LT1??

 

I have a 76 Laguna S3 with a factory 400. It's a 2 bolt main car. The 4 bolt mains actually do not help, and weaken the caps because of less "meat" around and between the bolts. I make 575hp in this car with no bottle, but it does get a 150hp spray on occasion. This engine has been in the car for nearly 2 years and I have had zero trouble with it. I have no cooling issues, either. I don't know how much more power you are looking to get, and maybe I've just gotten lucky...but I wouldn't trade my 400 for anything else. In fact, I would love to know if it's possible to adapt a 400 to work with LT1 heads and intake so I could put it in my 94 Z28.

Zach

 

In your opinion.

 

My opinion and the opinion of the machine shop where I live that builds 500-2500hp engines on a daily basis. Tell ya what...when I have a failure due to it being a 2 bolt main, I'll apologize. Until then you can just look at tail lights. I do, however, have a 4 bolt 400 that has cracked main caps. The mains of the 400 are bigger than the 350 (obviously) so when you put two holes, instead of one, on a fairly small piece of usuable metal you weaken it.

Zach

Remember, some horsepower numbers have been changed to protect the innocent.

Besides, anyone with a stick Super Duty has no room to talk about strength or durability. Non serviceable ZF=paperweight. The Ford dealership I work at quit ordering them because of so many recalls and failures.

 

LagunaS3: Just out of curiosity, how much power were you getting out of that 400 block before it cracked? I'm trying to get an idea of how much abuse these blocks can take and still be "safe."

 

It was the exact same engine as the 2 bolt main. After the 4 bolt cracked I had the crank turned and polished and put everything from the 4 bolt in the 2 bolt. I realize I could've just gotten lucky with the 2 bolt...but I have 3 friends with pretty close to the same engine as I do (2 bolt)....within 20hp anyway. We haven't had any trouble from our engines. You probably know, but it is VERY important to have the steam vents drilled into 400 heads...they cannot sustain RPM's over 3000 without them. One thing I had done to mine was I had every cylinder nickel sleeved. I will PM you with the HP and TQ numbers of my engine.
Zach

 

I have rebuilt a couple of the ZF boxes....parts are availible, not many ford techs can rebuild a tranny...The only failure point is the weak FORD/Valeo clutch that comes in them. Mine has a dual-disc ceramic clutch which will not fail....our two pull trucks make over 700rwhp and have not broken a tranny, just clutches.