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70valiant' engine build for 200 HP
https://www.slantsix.org/forum/viewtopic.php?t=43366		 Page 1 of 2
Author:  Dart270 [ Mon Jan 24, 2011 2:57 pm ]
Post subject:  70valiant' engine build for 200 HP
Phil and all,

It was asked by the man above: "What does it take to put 200 HP to the road?"

First, it might be a good idea to read this thread:
http://www.slantsix.org/forum/viewtopic.php?t=23314

Second: I interpret this as meaning 200 HP at the crank. 200 HP at the rear wheels means around 250 HP at the crank.

Third: Here, I give a recipe for what I would do to make an honest 200+ crank HP with a used assembled shortblock like Phil's (160 psi cranking on all 6). I successfully did this (200 HP - original Project V motor) with a junkyard shortblock w/o full compression on all 6, a good head, and 8.7:1 comp.

- Mill head for 9.5:1 comp
- 234/226 @ 0.050" Oregon cam or 280/270 Erson cam, degreed at 99-101 (can use silent chain or double roller) Safest to use regrind OEM cam, although I'm not sure any Ersons have wiped out oil pumps
- 1.70/1.44 Engnbldr valves, new guides
- 340 springs and retainters
- port work, mostly on the bowls and knock down guides
- reuse stock oil pump if pressure is good, and put in 1-2 washers under relief spring to bring PSI up to 55-60 @ 2500+ RPM
- stock balancer, rocker gear
- baffle oil pan at least to the rear and make sure pickup sits on the floor and near the center of the pan. If engine not out, just use it as stock and see what it does on hard accel (oil press gauge blips down? baffles...)
- Offy 4bbl intake with one of these carbs: Holley 500 2bbl, 390 4bbl, or Edel 500 4bbl
- headers to 2" secondaries into Flowmaster Y pipe under trans X member and then into 2.5 single out the back
- recurve dist for 10-15 deg initial advance, 28-30 deg final (mech), and 45-50 final with vac (cruise)

If this is badly ported/tuned/assembled, it should make 180 HP, if well ported/tuned/assembled, 220+ HP? Head porting is biggest unkown, besides care of assembly, in success. This should get you around 16 flat in a 3300 lb car (Volare wagon) and have smooth idle and be totally streetable.

I will be building an aluminum engine to nearly these specs in the near future.

Hope this is helpful!

Lou
Author:  DAlexanderW [ Mon Jan 24, 2011 5:04 pm ]
Post subject: 
What about for a solid 250 hp at the crank (or 200 rwhp)? How much more has to be done to get those kinds of numbers? And while we're on the topic of hp, what's the most anyone's reliably gotten out of a Slant six?
Author:  Dart270 [ Mon Jan 24, 2011 6:51 pm ]
Post subject: 
See the last entry in the thread I pasted in above. My '64 Dart makes 250 crank HP.

Highest Slant 6 numbers I know are 370 crank HP on race gas NA, 630 HP turbo'ed. Reliably? I'd say 330-350 HP on race gas, and about 300 HP on pump gas are best yet. There is A LOT of info (and "heated discussions") on this site about buildups like these.

Happy building,

Lou
Author:  sandy in BC [ Tue Jan 25, 2011 6:28 am ]
Post subject: 
Lous 200 hp formula is easily attainable by anyone. (I have done the same formula myself and made an estimated 180hp with a BBD)

Making 250 is likely to require more experience and considerably more money.
Author:  terrylittlejohn [ Tue Jan 25, 2011 7:52 am ]
Post subject: 
i have found with head pocket porting, if you get the shop to do a 70deg throat cut after doing seat enlargement, gives a nice line under the seat edge that if you grind back to gives good results.
Author:  Valleyant [ Tue Jan 25, 2011 10:51 am ]
Post subject: 
Lou,
Thanks for the recipe, always interested in proven combinations. I first want to say it was a pleasure to meet you, Dadtruck and wvenable in Clay City a few months back. Very nice to see ( in person ) the enthusiasm in Slant Six community.
I want to build a similar powerplant for my '72 Valiant daily driver. It might sound funny but it does alright with just 80 HP and 140 ft/lbs at the wheels (just under 3000lbs). Does great in stop and go but I want a little more power on the highway.
I know the head work will be the key. I will be using Dual Dutra Duals, and a BBD at first with the other items you listed....if I can double the power it is making I will be thrilled! Its gone 17.8 at 75MPH with1 barrel/ auto trans and 2.76's out back :D
Author:  70valiant [ Tue Jan 25, 2011 1:27 pm ]
Post subject: 
Thanks Lou,

I want to make as much HP as I can while keeping it reasonably well mannered on the street. Milage isn't a really big concern, I have a very short commute to work and the overdrive will keep the highway milage in check.
Author:  Dart270 [ Tue Jan 25, 2011 2:10 pm ]
Post subject: 
Sounds like a good plan, Valleyant! Fantastic to meet you too, and hope we can entice you to 1 or more Slant races this year with your car.

If you set these up right, mileage should be close to stock. My 250 HP '64 Dart gets the best mileage of any Slant I've owned!

Lou
Author:  slantzilla [ Tue Jan 25, 2011 6:25 pm ]
Post subject: 
Easiest way to make 250 is build a 100 horse motor and put on a 150 shot. :lol: :lol: :lol: :lol: :lol: :lol: :lol:
Author:  emsvitil [ Tue Jan 25, 2011 7:00 pm ]
Post subject: 
Quote:
Easiest way to make 250 is build a 100 horse motor and put on a 150 shot. :lol: :lol: :lol: :lol: :lol: :lol: :lol:
Nope,

detune a 500 Hp motor..............
Author:  62 alum [ Wed Jan 26, 2011 12:26 pm ]
Post subject: 
Lou Would the two cams you suggested on this build also work with a hyper pak intake and exhaust header? I had my head built the same as your post. My valiant is a 4 sp od with 4:11 gears and 2800# mainly a summer time fun car not a every day driver. What I would like is a cam that works well with the hyper pak and has some streetable.
Author:  Dart270 [ Wed Jan 26, 2011 3:04 pm ]
Post subject: 
Yes, these cams are fairly close to the original Hyperpak cam, actually.

If below about 9:1 comp, use the smaller one. If above 9:1, use the bigger one. Not too much risk in going with the bigger one since you have a stick.

Lou
Author:  DadTruck [ Wed Jan 26, 2011 4:53 pm ]
Post subject: 
Valeyant,, good to see your name here on .org,,, I agree with you,
the enthusiasm and expert advice found here,, is the best.
good luck with your project.
Author:  wvenable [ Wed Jan 26, 2011 5:10 pm ]
Post subject: 
Valleyant, I second DT. Hope to see ya at Clay City again. Please let us know how your stuff is going! All the best, Wayne.
Author:  62 alum [ Wed Jan 26, 2011 6:30 pm ]
Post subject: 
Lou thanks for the info. I had .080 took off the head but really do not no where that will put my c.r. From what I have read on this site I am still below 9 to 1. so I will go with the 280/270 Thanks again
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