Supercharger requirements

[Laowho]

Pretty much exhausted the research I can do so need you guys to tie up our loose ends/make sense of it all. Our aim is to have the most fun/responsive street/hwy driver worthy of a non-race 2d Gen Charger. Willing to leave the cost/benefit analysis aside in favor of just getting the performance we're after. Have a fresh 440 w/ 906 heads, deck was milled but not zeroed so compression is about 9.5:1 and Keith Black 10:1 flat top pistons. We're definitely goin the FiTech EFI route no matter what, so tune shouldn't be an issue. Has 1 3/4" TTI shorties, 2 1/2" exhaust. Dyno-ed at 435hp/520lbs/ft tq, and would like to be at at least 500hp. Mild Hughes flat tappet of only 223/228 and LSA of 111 seems suited to a Paxton centrifugal for only about 5lbs boost.

Questions are whether we'll realize the desired gains and responsiveness with our heads and headers, and whether 9.5:1 compression is still safe given low boost levels and FiTech auto tune. On the cost/benefit side performance-wise, seems the only thing that would matter is if our heads/headers wouldn't adequately support modest boost, but honestly, from what I've managed to gather, I wanna believe that we're the perfect candidate for some stock-ish improvement.  Thx for anything I'm missing.

[Troy]

I wouldn't think you'd need boost to get 500 hp. Pretty soon you'll hit the limits of everything else (tires, suspension, brakes, etc.).

http://www.dodgecharger.com/forum/index.php/topic,79069.0.html (This one is now running EFI)
http://www.dodgecharger.com/forum/index.php/topic,63179.0.html
http://www.dodgecharger.com/forum/index.php/topic,52477.0.html
http://www.dodgecharger.com/forum/index.php/topic,36603.0.html
http://www.dodgecharger.com/forum/index.php/topic,35116.0.html
http://www.dodgecharger.com/forum/index.php/topic,37136.0.html
http://www.dodgecharger.com/forum/index.php/topic,104749.0.html
http://www.dodgecharger.com/forum/index.php/topic,121321.0.html
http://www.dodgecharger.com/forum/index.php/topic,68741.0.html
http://www.dodgecharger.com/forum/index.php/topic,45552.0.html
http://www.dodgecharger.com/forum/index.php/topic,14847.0.html

Troy

[Lennard]

9.5 : 1 compression seems a little high for a roots blower. From what I've read they like 8 to 8.5 : 1 compression ratio.

[Laowho]

That's some serious linkage Troy. Tried to find "proven builds" here but never was able to. Many thanks. But Lennard, is this a Roots style? Definitely not PD, and have seen some posts that were doin it w/ 9.5:1, but yeah--this was definitely our biggest concern. Off to read those threads. Thx.

edit...Okay, I get the drift, and Engle cams are news to me. Dunno how I haven't come across these. Indy or Eddy heads. And good news is everything else is still up to snuff for our goal.

[c00nhunterjoe]

I dont think your 906s in their current state would adequately support a blower. The cost to port them wouldnt be cost effective.

[PRH]

I would have no problem exceeding 500hp from even stock 906's with 5-6lbs boost in a combo similar to yours.
However, I wouldn't even attempt to do it on pump gas, 9.5cr, and no quench.

That just sounds like a recipe for spending a fair amount money with almost certain unsatisfactory results.

Aftermarket closed chamber heads, a bigger cam, full length 1 7/8 headers...... 500hp on pump gas easy peasy.

Here's one from last spring:
446, 10:1 with kb 237's, stage 1 sidewinder heads, rpm, QFT ss830 carb, my 2-2 1/8 x 4 dyno headers(the motor would lose about 15-20hp with 1 7/8 x 3  headers), .540/.550 solid cam.

Rpm------TQ/HP
3500----498/332
3600----499/342
3700----497/350
3800----494/357
3900----493/366
4000----506/386
4100----522/408
4200----542/433
4300----543/445
4400----553/463
4500----553/474
4600----543/476
4700----543/486
4800----543/497
4900----536/500
5000----529/503
5100----523/508
5200----518/513
5300----508/512
5400----509/523
5500----506/530
5600----499/532
5700----488/530
5800----480/530
5900----485/545
6000----481/549
6100----472/548
6200----466/550
6300----458/550
6400----448/546
6500----433/536
6600----423/531

[Laowho]

Thx guys. Yeah c00n, that's what I was afraid of. Thx RPH--those are some serious numbers, higher than we're after, and will have to wait to see if a bump in cam and better heads can still use our small-ish headers/exhaust. Intake isn't a big deal. You've all chased me back to basics and thatsa good thing. We're definitely goin w/ the FiTech EFI and OD. For the OD we've already talked to Jamie Passon and b/c we're never racing it, and it's gettin equal use b/t back roads and highway, we're keepin our 3.23 rear wh/ will work well w/ his more affordable 23-spline a833 4-speed OD w/ 3.09 1st. All reasons to not go much over 500hp target in the end (plus the added savings of not needing heavier guts/springs, etc). We'll revisit the engine after the EFI and OD, but have been trying to put together a complete picture before getting underway. Sorry for the attempt at a SC shortcut. We'll take it one step at a time.

[PRH]

IMO, if you're serious about more power, you should change the heads before you put the motor in the car.
That will be the biggest gain initially, and will work with all the other pieces you already have.

[Laowho]

Thx RPH, that was our original intention even b4 we bought the car, but mainly b/c I'd assumed that the heads were original w/ the '74 block. When I learned they were '69 heads I was a little relieved, but you know how it goes. Moreover, I've yet to come across such a small cam in a 440 rebuild. Tried to appease myself w/ things like, "It's just a driver" and such, but it just doesn't seem we're doin justice to the block or the car. Figure the ARP bolts they put in the rebuild will suffice for around 500hp, and even tho they said it's a forged crank, I doubt it, but cast is still enuf for what we want. If we were lookin at 600hp we'd be changin everything out and gettin the stronger tranny. Bottom line, if we're changing out the heads we're puttin in a better cam with it, just enuf to edge up to the limits for our 1 3/4" headers. Have already read/seen that these and the 2 1/2" exhaust match up well enuf to this still moderate hp.

[Troy]

That's some serious linkage Troy. Tried to find "proven builds" here but never was able to. Many thanks. But Lennard, is this a Roots style? Definitely not PD, and have seen some posts that were doin it w/ 9.5:1, but yeah--this was definitely our biggest concern. Off to read those threads. Thx.

edit...Okay, I get the drift, and Engle cams are news to me. Dunno how I haven't come across these. Indy or Eddy heads. And good news is everything else is still up to snuff for our goal.

Proven Combos is a "child board" of this one.

Troy

[PRH]

Considering the OD trans, I'd stay on the conservative side with cam selection.

If it were my choice, I'd go with something smooth and stable......like a Howard's Rattler 728041-09.
Duration wise...... That's about as big as I'd go.

[Laowho]

Thx Troy. I was usin the wrong search term. Got it.

Yeah RPH, those numbers are what we're after. Another grind I've never come across, but the page says it's expressly for 383/440. Sounds classic, w/ just a little meanness

https://www.youtube.com/watch?v=Cux99Cs4Zsc

https://www.youtube.com/watch?v=qS8Nzcxn7Mc

Doesn't mention the LSA but I'm kinda hopin for sumthin closer to 108 than our 111, least from what I've read. And I know our H crossover cuts some tone but we're completely w/o lope right now. Thanks man. Also came across this--"A good lesson from Steve Dulcich is to take the stock specs of what Mopar originally put into the motor, and add no more than 10% of stock duration. And add no more than .050" to the stock lift, you will have a very sweet street engine."

Can this be right? OE Duration at .050: 268 int 284 exh...Lift: .450 int .458 exh... 115 LSA

https://www.yearone.com/Product/1966-74-a-b-e-body/fd1278

Okay, I got a lot more reading to do. Don't get me wrong, it's a very streetable motor, but just not quite there. Feel a little vindicated to constantly think we're just leavin too much on the table. Thx.

[1974dodgecharger]

hahhahahahahahah........GOOD LUCK AND HAVE FUN 

anything is possible......but you will get ADDICTED TO BOOST!

[Laowho]

Has great torque low-mid, but lookin at the proven combos has me wanting the Lunati 60303 and Eddy RPM heads for what we're after and the 600 FiTech. Will still have vacuum and work w/ the 3.09/3.23 First. Not lopey but should get us 550hp? Itsa start. The FiTech will have the power adder just in case.