Vinny P

Mark,

Thanks for the great information. I was expecting to have to do some port matching whether I use the oval or rectangular intake.
As I said, both Dart and Brodix recommend using an oval intake. They say that at 5500 it will still flow enough to keep up with the heads and produce better power across the board. I am going to give Wilson manifolds a call tomorrow to get their input . I will be using their tapered spacer as well. I have heard of great results with this type of spacer. I have a friend who has tested several spacers on a dyno, he says the tapered Wilson is the best. I will post what they have to say about this.

http://www.wilsonmanifolds.com/

PatriYacht

I'm using Merlin rect. port intakes on my 540's with AFR 335's. It's my understanding that the Merlin runners have a smaller cross section than Dart or Brodix. The port match was very good. Probably less thana 1/16 off. I never dyno'd mine but board member RLW got 700 hp using a Merlin, AFR heads and a small Comp cam. While I've had problems with idle quality (too large of a cam), I've never had a problem getting on plane because of not enough torque.

KAAMA

iTrader: (1)

Patriyacht,

I thought you bought the 315 AFR cnc ported heads??? Are the 335's you have cnc ported? Glad to hear it's running well for you. What size cam are you running with your combination? What size of AFR heads and cam is your friend "RLW" running?

The cams I will be running are just some little fellers (duration at .050 is 232*/238* on 112* lobes .578" lift on both sides). The 357 cnc ported AFR's really flow well---especially the low lift flow numbers. I'm thinking the cam should really work well with the AFR's I have.

RLW

Gentlemen,
I am running the AFR 305 "CNC'd Chamber" heads on My Dart Big M based 540.
My cam is a custom ground hydraulic roller CompCam.
Specs are as follows:
Intake/Exhaust
285/[email protected]"
236/[email protected]"
.630/.635 lift
112 LSA
I am not sure at what point the ICL is installed. Have to confirm that with my engine builder. Possibly at 112 degrees according to the Cam Card.

I am seeing 700 ft/lbs at 4900-5000 rpm. I feel this is too far up in the rpm range. Horsepower is 718 HP at 5900 rpm. Also too far up in the rpm range. I am now seeking solutions to get these rpm numbers lower at the cost of sacrificing HP and Torque.
I suggest a cam choice to get your HP down to 5400-5500 rpm and torque down in the low to mid 4000 rpm range. This will prevent torque loading the outdrive.
I am presently using a Merlin single plane intake with a Nickerson 1050.
I really don't want to get into a cam change but am seeking out alternatives.
This is installed in a 1989 27' Activator with XR/Imco 2" Shortie combo.
I suggest a call to RMbuilder for cam choice. He really knows his stuff and I wished I had known him prior to this build. Maybe he'll jump in on this thread.
Russ

Vinny P

RLW,

I have installed an Isky hydraulic roller.
intake .578 lift 238* @.050
exhaust .608 lift 248*@ .050
114 lobe seperation
installed @ 111*

I also have a Dart Big "M" as a block , AFR 315 cnc heads, 9.25 compression. On my desktop dyno, the h.p. peaks @ 660 @ 5500 rpm, torque peaks 680 @ 4500 rpm.

RLW

Checkmate540Bulldog ,
Can you run my numbers in your DeskTop Dyno?
My compression is the same at (9.25:1). I am curious of the outcome.
I like your numbers. I know this is an intake thread but it's all good stuff.
Russ

Vinny P

RLW,
I would be glad to. I just need your valve timing #'s. My program doesn't work off of duration, it calculates off of the valve opening and closing points. IE: Intake valve opens @ xx* and closes @ xx*, exhuast opens @xx* and closes @ xx*.

Have your heads been modified since AFR did them? If they have been, I need the flow #'s, if not I have the original #'s from AFR.

PatriYacht

Kaama, The cam I used was the Crane 651 with 244 intake@ .050, 256 exhaust, .630 lift. It worked great in my old engines with Merlin heads. When I changed to the AFR's the whole personality of the engines changed. The heads flow so much more that the cam seemed larger. The idle quality went to hell and the exhaust reverted badly. I'm guessing that the power peak is in the 6000 rpm range, an rpm these engines will never see. I'm thinking of trying the cam RLW was using. However, he's thinking of going smaller... Going to the Pirates Ball this year?

cstraub69@comcast

Actually you don't want the intake to line up with the head perfectly. You want the head to be above the floor of the intake about .100". A little step there to promote better "mixing".

Chris

robyw1

You will be very pleasantly surprised with the oval port intake. It will keep velocity high and carry a wider torque range as opposed to the narrow higher peaking torque of the rectangular port intake. If you're into racing then it would probably be better to run the rectangular port. I say probably only because I'm not convinced that the rectangular port even could stay with the oval port at peak horsepower in this 5500 RPM application.

Roby