Building a 400 small block
 

I have a 400 small block, four bolt main, with 202 double hump cast iron heads. I am getting ready to build the motor. I would like to be up somewhere in the 11:1-12:1 compression area. I would also like to be able to turn about 8000 rpm's. I know i am going to have to have the motor balanced and blueprinted. What pistons, rods, crank, cam, etc., would you all recommend to get about 400 lb ft and 400 hp to the rear wheels with this motor. My dad owns a shop and knows many guys in the business, so machining and buying parts is not a problem i would just like to get your opinion on the right internals. thanks
bart

First off you do not need to turn 8000 rpm to get 400 HP/TQ. That will be very easy with a 400 with those heads and a mild cam and a cast bottom end. If you are intent on making some real HP go with a forged bottom end and dump those heads in the can. Get a set of 200 to 220 heads and stuff in a good roller cam. You will be over 500 HP/TQ and turn around 65 to 7000 rpm. It will cost $$$ but HP costs.

6500RPM will get you 400/400 at the rear wheels but you need way better heads and solid roller cam, it will cost a few bucks. With those heads you won't even make the 400tq at the rear wheels :D

400 ft/lb of torque at 6,500rpm gets you 495hp.

no you don't.

Not quite following your logic here :confused:

For a 400ci motor with a the correct high flowing heads and matching cam that you could drive on the street.

In order to get 400rwt and 400rwhp you would most likely have to spin the motor to 6500RPM. At somewhere around 6200 -6500RPM you will get your peak HP and somewhere below that in the 3000 - 5000RPM range you find your peak tq. :D

Ok so less rpm, better heads, and good cam. Got that, but what heads and cam? What pistons and crank? Thanks for all the help. Oh yea, it has to be streetable, but more horsepower the better, but i also want to be able to use the lowest octane gas possible, but i already know i will probably be buy 55 gal barrels of higher stuff. Just the lower the better, but hp/tq is main priority.

You say in your sig, 11:1 cr, what octane fuel are you running?

I run 93 octane, check out my heads ( flow 285cfm), or AFR 210's or Brodix makes some good 23deg heads. You need a cam similar to mine to make 400/400.

If you are worried about the difference in price between a regular and premium gas then you might want to rethink your goals, as I stated above it gets very expensive. It is fairly easy to get around 300RWHP after that the bang for the buck goes way down, another way to say that is you start spending alot more money for less HP gains over 300RWHP :D

Price of the fuel isn't a problem but obviously the lower the better. I am saving the motor thats in the car for everyday cruising. But still the car doesn't get driven a ton so that isn't a problem.
On the heads, i am lost with so many options. I don't know the chamber size, ports sizes or what not, becasue they don't show the flow on most of them, just sizes.

I usually run my 406 from 6500-7300rpm. HP/TQ? I don't know, but it runs OK. If you really want a motor that turns that kind of RPM your going to have to give up a lot of streetability.

I run 10.7:1 compression on 91 octane gas, your going to want to optimize your quench and go with a good aluminum head if you want the compression that high. For reference my quench height is .039" meaning the piston to head clearance is .039" Do a search and read up a bit. The cheap way to do this is to zero deck the block and use any standard .039" gasket. I had to get a custom gasket set from Cometic.

As far as rotating assemblies go, get a good light forged piston and a strong steel rod. I used 6" Scat H-beam rods(645g) with SRP forged pistons(424g), and a Scat 9000 series crank.

Also, run at the least main studs, if your not going to boost it or spray it much (<150hp) you don't need head studs.

A "street" solid roller is a good compromise between race and street. You can run more duration @ .050 with lower seat duration than a similar hydraulic. With my solid roller specs of 242/248 @ .050 I get 12-13" of manifold vacuum.

If streetability is your ultimate goal you may want to think about building a 427/434. The exrta cubic inches will lower the operating RPM and still make the same power.

One other thing I would recommend is that you install a deck plug kit. This reinforces the upper cylinder wall and prevents distortion. It's a cheap kit from Moroso. Also, why your in there install a oil galley screen kit, it has saved my butt once before when a pushrod blew out the side of a lifter. The stray piece was on the screen. :)

Good luck on your build, it's a lot of fun.

Ok, what about a set of gm fast burn aluminum heads? I ask so i don't do something stupid and regret it later.

Are you 400/406 guys running 2bolt mains turning those RPM'S?????

I think that you should ask dad or some of his friends. 8000 rpm and 12 C/R should get you very near 700 crank hp. With a manual tranny you could get nearly 600 to the rear wheels and it would be a fun car while it lasts. :thumbs:

Reliable 8000 rpm motors can be built at home for about $12,000 - $14,000

Megaladon: Yes, I have 2 bolt mains with ARP studs.
:cheers:

So do I :thumbs:

Ok so now that we have the insulting me part done with, what heads?

I have a 421 small blk, with 4 bolt splayed mains. Lower end all eagle. Hyd roller, with Dart Pro 1 220's and air gap intake with 750 Bg carb. I run my timing at 36 on PUMP gas, and she really loves the 100 & 110 oct I do not have any cooling problem at all with the 30 plus year old cooling system. My CR is 10:2 TO 1.

:cheers: Larry

Ok i checked them out and i am completely lost. the afr210's look good but i have no clue at the brodix site. too many and idk what i need where.

whats ur hp and tq? and on darts website, when it says 400+ ci does that mean i could run them on my 400?