Low CR 400's can make power!

Les Szabo · Post by **Les Szabo** » Mon Feb 23, 15 3:40 pm

Another mild build that makes power from a US site.

First Pull was with a stock 2bbl carb and cast iron intake, replacement cast pistons. Bored +.030, block decked to square it up, honed with torque plates, balanced assembly.

Heads were 346 iron with 2.14/1.81 valves and ported to give 250cfm flow at .500lift.

Camshaft Summit 6400 Hyd. 214/224@.50 - .444/.466exh with factory rockers. Recurved Distributor and Dyno Headers.

RPM.................TQ/HP

2500...............351/167
2600...............350/173
2700...............355/183
2800...............367/195
2900...............371/205 peak torque
3000...............368/210
3100...............369/218
3200...............366/223
3300...............367/231
3400...............361/234
3500...............359/239
3600...............360/247
3700...............354/249
3800...............351/254
3900...............343/255
4000...............337/256
4100...............329/257
4200...............325/260
4300...............326/267
4400...............323/270
4500...............322/276
4600...............307/269
4700...............318/285 peak horsepower
4800...............308/281
4900...............302/281
5000...............297/283

Next, add a Holley Street Dominator intake and a quick Fuel 950 Holley
2800...............346/184
2900...............347/192
3000...............359/205
3100...............374/221
3200...............376/229
3300...............383/240
3400...............391/253
3500...............396/264
3600...............397/272 peak torque
3700...............395/278
3800...............392/283
3900...............397/295
4000...............397/302
4100...............397/310
4200...............390/312
4300...............388/318
4400...............377/316
4500...............374/321
4600...............375/329
4700...............380/340
4800...............382/349
4900...............380/355
5000...............368/351
5100...............371/361 peak horsepower
5200...............362/358
5300...............345/348

7.515:1 CR, pistons were .120 below the deck.

Its all in the machine work and the Heads.

Les

Dave81 · Post by **Dave81** » Mon Feb 23, 15 8:40 pm

Bloody hell.....80 horse gain form just changing the intake and carb.........

If only the 318 would yield such gains.......

Les Szabo · Post by **Les Szabo** » Mon Feb 23, 15 8:46 pm

Thats next on the list Dave, there's some pucker 318 builds, not quite so easy as BB's, you have to give it a bit more thought but, 300hp+ isn't too hard with the right parts, I'll get something up soon.......just gotta get meself back on the ball....had enough of the computer today what with work and that

Les

Mossy68 · Post by **Mossy68** » Mon Feb 23, 15 8:58 pm

That is impressive , considering its basically a bit of head work and a cam.

Pete · Post by **Pete** » Mon Feb 23, 15 9:07 pm

I am a really big fan of the 400 - especially when stroked with some decent heads. Fantastic pick up and about the same Reciprocating mass weight as a 340.

I have got a spare 400 block and some OK(ish) heads and a Roller cam and would love to build another stroker, but I have no real need at this time .....hey ho.............

Les Szabo · Post by **Les Szabo** » Fri Feb 27, 15 4:23 pm

So should others, remember the 400/451 Koffel engines way back then, they were an out an out N/A race engine that made around 600hp, .043 rings and all that, expensive yes, and they did blow up but thats cos some tried N20 on them and they were not designed for it. You could go so much further than that today with the same set up with heads that flow well in excess of 350cfm. Thats the real trick, a motor that will rev to 7500 easy, and quick! enabling you to run 4.56>4.88 gears with a tall tyre, 5500 verters, and you can then 60ft the crap out of most other cars, that will win you bracket races in a well set up consistent car.

This build just goes to show you what the average street guy can do with his stock 400 if he chooses the "right" parts. 400hp+ can be achieved if you upped the CR just 1 point to a mind blowing 8.5:1, that could perhaps be done with head work or closed chamber heads and perhaps installed a slightly better cam, nearer .500". People have got to get their heads around the fact that it IS worth putting a set of heads that will actually flow some air on a so called "Dog" motor and using a Bigger carb than the books and most people recommend.

Les

Pete · Post by **Pete** » Fri Feb 27, 15 5:12 pm

I think that is the Achilles heel of the Hemi - socking great pistons that weigh a ton, so whilst the Hemi Heads can flow enough to rev hard, the piston mass is really big and limits the fun ....I think this is where the 400 / 512 scores.........