How would build a sbc 400 ? heads, cam ect

[aeroocoupe]

So this is what I got. I do drive in autocross and the street (speed limit in ny is 55mph) I don't want to be in between 4th and 5th gear no the hwy. The sbc 355 that is in the car now has a really big cam. I can't go into 5 gear till 65-70. I drive it like it stole it. I go back and fourth from 93 and e85 fuel.
Chevy 406 block
Tremec TCET17805 gear ratio 2.87, 1.89, 1.28, 1.00, 0.68
Moser rear 4.10 gears
Rear tire 25.7 (275/45/17)

Thanks Rob

[Kenova]

I can tell you how I built my 400, for what it's worth.

I did a cheap bearing and ring job on the short block. I even knurled the pistons.
The heads are early 1990's Corvette aluminum (way too small). If I had to guess, I would say the compression ratio is around 9.5 to 10.0:1 in at least some of the cylinders (maybe)
For a cam I'm using a Howard's hydraulic flat tappet with specs of 231/241 duration @.050 lift with a lsa of 112 degrees. Total lift with 1.6 rockers is .502". That is as much lift as the heads will handle without reworking or replacing them.
Headers are 1 7/8" Hookers (way too big) with 2 1/2" exhaust.
I am also using a 30 lb. external balanced flywheel and it is topped off with a Fi-Tech fuel injection and a small old Wiend single plane manifold.

I will be the first to say that it's CRAP, but I had the parts but no money at the time. I have so much confidence in it that I set the shift light at 5000 rpm. It still works surprisingly well.
This thing will idle at 750 rpm and pulls away from a stop sign with no effort (2.66 Magnum with 3.32 in the rear and 26" tires) and I can cruise at 60 mph while turning 1600 rpm. Anything lower than that and it's a down shift to 5th gear. The combo really needs 3.73's in the rear.



What would I do different?
Obviously a better short block is needed with a verified compression ratio of 10:1.
For heads I would probably use AFR's 200 cc head.
I would use a hydraulic roller cam with 236 to 242 degrees of duration with 1.6 rockers.
The rear end would definitely get 3.73's.

There are a lot of people smarter than me who would say even the new combo is wrong. The way I look at it, the modest cam shaft will preserve the torque while the heads with more lift would improve breathing at higher rpms.

In short, if I were to boil it down to one short sentence I would say "Build for torque".

Ken

[aeroocoupe]

I thinking about making it into 364. Looking to make around 500 hp.

[Jk918]

get some good aluminum heads, TFS, AFR, something 210-225 range, have 10.1 or better compression and a roller cam 230+ duration, roller rockers, forged pistons, and some decent rods. Will make 500hp and probably 470lbs .

[ilikeike]

Hello

Hi.

[ilikeike]

I used a Dart block
Went to 421”.
AFR 210 comp ported.
Howard’s small base circle Hyd roller 241/247 @ .50
Compression is 9.89.
Can’t recall the exact lift but around 540/550 or so
With. Single plane CNC port matched Vic Jr we dynno 498 hp at the wheel at about 6000.
Nice torque 3000 up peak around 4000 @ 480 tq or so at the wheel.

This was local custom built and balanced “ blueprinted” very well.
I pulled the Vic jr and have been running a rpm air gap with 1/2” open spacer below a 1/2” nitrous plate.
Very torquey !
I run it to 6500 rev limiter often when autocrossing I keep it in 2nd and it pulls hard from way down low.
Holley 850 xp ultra with annular boosters from AED.
I have a NOS cheater on it but with the 315s and a 5 spd and a 3.70 gear I’m already pretty traction limited and never use it.
I use a Holley HP ecu for timing,progressive nitrous control and data logging. I have MAP,AFR,TPS..even tho I’m carb’d.

Big SBCs are fun.

But fit the $$ I have into it I could have done a nice tame 600 hp LS