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What is the smallest lift cam that can make 250HP
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Author:  Aggressive Ted [ Mon Jan 28, 2008 5:58 pm ]
Post subject:  What is the smallest lift cam that can make 250HP
Quote:
A "Super Six" 2 bbl and a factory 6 into 1 cast iron manifold is not going to get you past 200 HP.

To make 250 HP out of 225 CID you are going to need some RPM.
To get the engine to rev to 5500 - 6000 RPM, you will need good airflow.
To get 6000 RPM out of a 225 you will need at least 391 cfm (4 bbl carb) head flow and a cam to get you there.
Some form of 3 & 3 split exhaust gives twice as much time between pulses, this really helps flow.... exhaust scavanging helps even more.
DD
Gents,

I have three extra motors and in the process of building another 225 SL6. What is the smallest lift cam and duration you can use and make 250HP, no nitrous, no turbo. Just 10 to 1 compression and the "Engine Builder" 1.7/1.4 valves and good porting. HP Peak at 5000 or lower if possible.

Thanks! :D
Author:  BigBlockBanjo [ Mon Jan 28, 2008 9:04 pm ]
Post subject: 
Ted,
In my .02....I would think a minimum of 280 dur. and .500 lift, if your keeping it under 5000. That, plus a well-modified head.
I know others could be an authority on this....
Author:  runvs_826 [ Mon Jan 28, 2008 10:30 pm ]
Post subject: 
Banjo's got it right on, it's going to take .5in lift with 280-300 duration. This is of course with a 1.5 rocker ratio, I would cut down on the duration with a 1.6 but keep the lift up. Make sure some good valve reliefs are cut into those pistons. Lots of headwork, including multi-angle grinds. The actual port and polish work I believe you could do personally for 250hp, and more than that you might want to consult a professional. Last is blending the intake with the head, which will be follwed off with a minimum of 400+ cfm carb.
There is a lot of things I wish I would've done better these being included. If you really want a screamer I would take my time and get my hands dirty like I am doing now (rod polishing). The head with some work can do it, but to get rpms I've learned it takes carb, intake, and cam. Good luck, shoot me a PM if you want to bounce more ideas.
Author:  Dart270 [ Tue Jan 29, 2008 7:28 am ]
Post subject: 
Why do you want the "smallest lift cam."

What car/drivetrain will this go into?

Lou
Author:  Aggressive Ted [ Tue Jan 29, 2008 8:49 am ]
Post subject: 
Dart 270,

It will go into a 69 or if I can't find one a 70's two door.
904 automatic with a 8 3/4 rear.

Less wear and tear, more bullet proof for consistent runs and longevity.
This would be a street car with allot of strip time.

Is 200HP hitting the wall? and 250HP asking too much naturally aspirated?
Is 225HP more realistic?
Doctor Dodge came up with the HP.
Author:  argentina-slantsixer [ Tue Jan 29, 2008 12:27 pm ]
Post subject: 
I'd go with .450 lift for increased valvetrain stability and troublefree service. Also a RDP cam profile, say,

292in/280ex .440in/.465 ex lift at valves @ 1.5 rocker ratio, 242/230 @ 050, 112° LSA 108 ICA.
Author:  Dart270 [ Tue Jan 29, 2008 3:11 pm ]
Post subject: 
The main part of my question actually involved converter stall, although I didn't say it explicitly.

Anything over about 225 @ 0.050" duration will not be nice at low revs with a stock converter. Even 220 @ 0.050" could be bad if not set up properly.

I like Juan's profiles (maybe only 6-8 deg @ 0.050" split between int/exh), although I would feel fine with 0.480-0.500" lift in mixed driving. However, they will require bare minimum 2500 stall to work best. I wouldn't fool with anything under 2800, personally. With a modern converter, you'll hardly know the difference until you stand on it.

Lou
Author:  Aggressive Ted [ Tue Jan 29, 2008 4:19 pm ]
Post subject: 
Dart270,

Who's converters do you recommend?
I know if you buy one for a V8 they do not react the same with a 6.
So numbers are always off unless the stall is listed specifically for a 6.
Are any available off the shelf that conform to your recommendation?
If you would please share a supplier and part number.

Thank you very much!
Author:  argentina-slantsixer [ Tue Jan 29, 2008 7:33 pm ]
Post subject: 
Quote:
The main part of my question actually involved converter stall, although I didn't say it explicitly.

Anything over about 225 @ 0.050" duration will not be nice at low revs with a stock converter. Even 220 @ 0.050" could be bad if not set up properly.

I like Juan's profiles (maybe only 6-8 deg @ 0.050" split between int/exh), although I would feel fine with 0.480-0.500" lift in mixed driving. However, they will require bare minimum 2500 stall to work best. I wouldn't fool with anything under 2800, personally. With a modern converter, you'll hardly know the difference until you stand on it.

Lou
Oh! I wasn't thinking about auto tranny... I was thinking A833 close ratio with a 3.23 minimum rear end ratio... 3.54 perhaps... or a 833OD with low 1st (like passonperformance builds) and a 3.81 rear end. Recurved dizzy, and PLENTY of head work. Maybe webbers ITB's :twisted:
Author:  Dart270 [ Tue Jan 29, 2008 7:49 pm ]
Post subject: 
I would not buy an off-the-shelf converter, period.

I recently bought one from Midwest Convertors (search net) and it was dead on. Talked to them on the phone about my car and motor and stall spec. Around $400 shipped with custom small pilot (extra few $) and large input splines. 9.5" and 2800 stall on that motor. They can give you whatever stall you want. Slantzilla and others have also had great luck with them.

Other people have used Edge Racing and Continental in SoCal (actually, I had one successfully modded by Cont in 1999), and PTC in GA.

If you really are going to make 250 HP NA, and for a street/strip app, then I would recommend 3000-3400 stall. I got 20+ MPG with a 3600 converter and 250-270HP and it ran low/mid 14s.

Lou
Author:  Aggressive Ted [ Wed Jan 30, 2008 1:16 pm ]
Post subject:  What is the smallest lift cam that will make 250HP NA.
Gentlemen,

This is excellent information.
Thank you for your time and sharing your experiences.
I will add this data to my engine build plan.

Thanks! :D
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