Team Chevelle banner

400 Small Block Build And Dyno Test

56K views 341 replies 53 participants last post by  cage2592 
#1 ·
A forum member had me build a mild 406 for his 71 Chevelle, I thought I would post some pictures. I had a very nice thick 817 production block, bore and stroke 4.155 X 3.750, with a 7/16 6 inch rod and a Mahle piston, we ended up with 10.3 compression. The cam is hyd roller, 234/238 @ .050 .560/.530 lift on a 110. We used a AFR 195 head with modifications and a performer RPM air gap intake with a 1 inch open spacer. Carb is a AED 750 CFM. We plan on testing different distributers, locked and with a timing curve. Gas will be 91 octane from 7-11. Should be a interesting build. I should mention the valve job from AFR was a disaster.
 

Attachments

See less See more
2
#2 ·
HI
Very interested in the dyno sheet . Considering the emphasis on mid range is the dyno sheet going to give readings between 2500 thru 6500??
engine vacuum at idle eg 12 inches at 850rpm ???.
Results for dyno 400 street motors are a little scarce most hardly include any details .
As street motors can have vastly different rear gear the dyno curve is interesting 2500---3000 rpm
To get the most out of any top end a dyno test will also show how quick the drop off is after peak at up to 6500 for tq and hp

A guess for peak tq is at 4800rpm ,Peak HP at around 6000rpm
manifold and heads would be ok but I would consider them the limiting point

Seen 5 deg smaller cam with 195 street AFR and Weiand single manifold similar build . Corvette forum Wes Migletz

Hope test goes well.
 
#5 ·
I'll make a guess on Torque and Power numbers



Trq 488 @ 4500 rpm
HP 514 @ 6000 rpm
 
#7 ·
I built a nice little 406 a few years ago for a truck.

I too will be interested to see what this mighty mouse makes.


76 impala 400.

Bored .30 over.
Scat internally balanced 5.7 rod crank.
Scat 5.7 rods.
DSS forged pistons.
Dart 200cc SHP heads. (ported and polished) bench flow tested to 218cfm....
Crower roller cam and full roller valve train. 1.6 rockers. Cam number 00469
MSD ready to run distributor.
Performer RPM air gap intake.
APR studs and bolts through out.
10.1 compression
Fast EZ EFI.

With a 850 DP on the dnyo it made 474hp @5800rpm and 514 ft lbs @4400rpm
 

Attachments

#148 ·
Did anyone digest the dyno sheet and realize the BSFC are extremely high and look at the LBS/HR of fuel. Then you look at the SCFM is down because there is so much fuel going in the engine. A good BSFC 0.39 to 0.43 and look at your A/F ratio does not look good. Using that much fuel is why you needed to run 38 degrees of timing. Less fuel you would have seen a better A/F ratio less LBS/HR and better BSFC numbers and with less fuel going in the engine would picked up your SCFM #s quite a bit. You would have seen a better HP number as well and would not have had to run 38 degrees of timing.

Most of my builds peek timing is always between 32 and 34 degrees total timing.
 
#10 ·
Are you finding that those 1" spacers are pretty consistently giving you a little extra power, or is it just something the customer wanted?
 
#12 ·
530/500+lbs.
You know I love these engines! Mine had/has the OTB 195 64cc comps from 15yrs ago (on the engine in my sig)!. Still going!
6" scat H with beams,7/16 bolts, -22 D dish Mahle's 2 bolt studded mains.
 
#13 ·
Really interested in the results too because when I added the 1' spacer to my RPM Performer on my 406 it really woke it up.No real dyno results however it felt better all through the gears.
 
  • Like
Reactions: WHT/73
#15 ·
Mine needed it too. This was when the 355 had those heads(my AFR's) and the A/G. car slowed down without it.
No dyno test, just track.
Whoever gets this 406 will be very happy, maybe even surprised what they can do.:thumbsup:
 
#16 ·
Mark, I love your builds.

I have a question, hope this is not too far off topic - my taste in camshafts tends towards very mild. I used a Lunati 228/238 @ .050 hydraulic roller cam which I bought from you in my 496 BBC, and the performance was superb, but for street driving it was a bit choppy for my taste. I drove and raced it many years, no complaints, but I'm getting old I guess :)

I currently have a 355 SBC in my Impala with another Lunati hydraulic roller, this one 219/227 @ .050. This one is perfect for my taste - very smooth idle, works perfectly with stock converter, pulls hard to near 6000 with EQ heads.


So finally circling back to my question(s) - I'm considering a big inch SBC for my Impala, wanting to improve performance without sacrificing the nice street manners. I'm therefore interested in something like your 406 here, but with a camshaft more like the 219/227 stick, understanding that I may be able to go a tad larger in a 406.


1) Any idea how much the dyno numbers would suffer with the milder cam?

2) Would something like my 180cc EQ head be a better match with the smaller can than your AFR195's?


Thanks!
 
#18 ·
"I had a very nice thick 817 production block"

This was the case with my 817 casting. It was safe to go .060 over, for 412cid.
 
#20 ·
Hi
ON A 400SBC [not a 383]

Ideally AFR 195cc competition or prefer AFR 210 competition heads for street usage
Chevy 23 deg heads flow poorly compared to most other engine brands .

The Ford Windsor AFR head 200cc has a 2.160 port cross section [small port BUT BIG flow ]
The Chev head 220cc has a 2.180 port cross section [Larger port big flow but slower flow ]

For 230 up to 250 deg at .050 HR or SR cams
195 afr heads flow to approx. 5800--6100 requires single plain for higher rpm peak vic jnr etc
210 afr heads flow to approx. 6000-6200 vic jnr etc

On the smaller heads the single plain increases pk hp by up to 200-300 rpm

220 Afr heads will flow to 6500rpm ,,,,, not much info on this head
227cc heads flow to 7000rpm 260+ SR cam

Evidence of AFR 227 head needing big SR 260+ 275/60/15 tire , 4.3 rear gear, 4000--4500 stall
 
#27 ·
I don't want to spoil anything just yet, as Mark just finished dyno runs. I'm sure he will post more results that he has. I think this will surprise some. He's put a lot of time and own custom touches into this build and its been highly educational for me as well. Those that have talked to him know he's a perfectionist. I cant thank him enough for taking this build on.

Current setup:
CPP full Pro-Tour kit
Viking coilovers all around
dropped 2" Front / 3" rear (2" rake)
18x8 front / 20x10 (28" tall) Rear AR Torq Thrust II's
TH350 w/Vigilante 2800 Converter.
3" stainless exhaust (no X or H) through Dynomax Ultras (turn downs before rear).
Gear selection is still considering.

This is a daily with power brakes and A/C, with a request that its street-able for PB, AC and 500+hp.


Some may have read that my old 406 wiped the #5 INT lobe and I was originally going to upgrade to a roller. By the time I ran the numbers on a roller change from FT and AFR's, It made sense for a rework. By then I was into a new build cost. Thought about a Crate and looked at all of them but didnt find one worth much. So I called Mark.

Old 406 Engine:
750 Holley DP
Edel Perf RPM (Non Air-Gap).
Moroso 1" Carb Spacer.
Eagle Street/Strip balanced rotating Assembly (ESP-13008030).
Cast 3.75 crank.
Forged I-Beam 6" Rods.
KB Hypereutectic Pistons (9.6:1 Comp).
Sportsman S/R Iron Heads
CC XE274H FT (230 INT/236 EXH, .490/.490 (@ .050) w/12"vac.
Harlan Sharp 1.6 rockers (Brings lift to .525)
Timing 36* all in by 2800rpm.


More to follow.

Mike
 
#32 ·
643/553:smile2:
 
#36 ·
HI
AFR 220 on 400 cuin peak hp about 6400 -6500
Afr 227 on a 400 cuin peak about 6800rpm 260+SR


400 cuin
195 change to 210 10hp increase 540hp upto 550hp

super victor manifold gets +15 hp over a vic jnr manifold
11:1 CR plus 1/2 point compression and 5 deg more cam SR 15 hp gain
Original HP 550hp
after upgrades 580hp

More cam 260+SR
AFR 227
compression 12:1
640hp at 68oorpm
 
#37 ·
I didn't want you to short change yourself.:D
 
#38 ·
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top