tblrklakemo

There has been much debate and speculation on the subject of 496mag and HO header applications. The CMI's are a PITA to install and are very $$$. Dana marine and eddie marine both have torque tubes that claim about the same HP gains but cost over a 1000 less than CMI's and are direct bolt on replacements. Are the HP #'s correct, and do they sound as good? Worth the savings?

FeverMike

I'd go with Stainless Marine or Eikert. They are the best cast headers you can by. They have proven on the dyno at Innovation Marine to make the sale power or more than CMI's. There was a dyno sheet on this going around back in 2000-2001 tesed on a HP500. I had Stainless Marine headers on a Merc 502 MAG and they are easy to put on and will last a long time.

Pismo10

Heres a dyno test on the HP500 using various headers. It is off OSO somewhere.

HP
RPM "CMI
Tube Top" "CMI
Elbow Top" Stellings Eickert "IMCO
Powerflow" "Gil
Merc Ex" Stainless Marine "Merc 500HP
Engine"

2500 217 213 214 223 217 215 214 225
2750 254 240 240 260 245 239 239 250
3000 284 258 268 289 268 268 267 280
3250 306 304 296 316 305 297 295 309
3500 345 337 324 337 341 321 318 335
3750 376 371 354 360 371 347 346 360
4000 404 398 381 387 398 373 371 385
4250 426 417 410 419 425 401 400 405
4500 448 438 437 449 442 428 427 428
4750 468 460 461 478 461 451 452 448
5000 485 476 478 493 471 470 471 458
5250 499 492 491 505 481 487 488 466




Torque
RPM "CMI
Tube Top" "CMI
Elbow Top" Stellings Eickert "IMCO
Powerflow" "Gil
Merc Ex" "Stainless Marine
v1" "Merc 500HP
Engine"

2500 456 448 450 468 456 452 449 472
2750 485 458 458 496 468 457 456 478
3000 498 451 470 506 470 470 468 491
3250 495 492 478 510 493 480 477 500
3500 517 506 486 505 512 482 477 502
3750 526 520 496 504 520 486 485 504
4000 531 523 500 508 522 490 487 505
4250 526 515 507 518 525 496 494 501
4500 523 511 510 524 516 499 498 499
4750 518 509 510 529 510 499 500 495
5000 509 500 502 518 495 494 495 481
5250 499 492 491 505 481 487 488 466

Pismo10

I downloaded this from OSO years ago. It goes

RPM
CMI Tube Top
CMI Elbo
Stell
Eickert
Powerflow
Gil
SM
Stock

I cant seem to upload an xls file type.

tblrklakemo

Is a performance manifold like a dana or eddie product going to sound any better than my stock HO pieces, or do i have to go right to equal length headers like CMI sport tubes to get a better sound?

Sydwayz

iTrader: (1)

Fred at Trick has switch from CMI to Stellings for his distributorship.

I also know that Basset is now producing a set of 496 headers. They are working on the accessory adjustment kit.

yesrej

i have asked about the bassets a few times and got no info.

Undertaker

Just ordered the new Dana Marine exhaust for my Donzi 22 classic w/ 496 HO was told 40-45 hp gains about 3 hrs install time and if ya put there new exhaust tips on you will notice a VERY NICE sound.....can not wait for spring

Undertaker

Purchased mine from Jaime @ Lakeside Restorations a sponsor on here give him a call he is very knowlegeable and willing to answer any questions IMO. Good luck

BGIII

iTrader: (3)

Pismo, here is a graph that I believe uses the same info you posted.