Harrop Dual Plane/Single Plane Manifold on 355

General Tuning Questions And Discussions
Post Reply
User avatar
JBalsar
Posts: 10
Joined: Thu Aug 04, 2016 1:21 pm
cars: 1923 T Bucket
1928 Model A Pickup
1928 Model A Tudor
1968 HR Holden
2005 Holden SS Crewman

Harrop Dual Plane/Single Plane Manifold on 355

Post by JBalsar »

Hi All,
Has anyone changed from a dual plane manifold to the single plane on the 355 engine?
Just did a couple of dyno runs and it doesn't want to make any power after 5800rpm. Fuel looks good and my timing is around 34deg. running the 1000cfm 4 barrel throttle body.
(I know Harrop says they are good till 5500rpm so I'm guessing that may be the problem
immortality
Posts: 3416
Joined: Thu Apr 09, 2009 12:31 pm
cars: VH, VN, VS, VX

Re: Harrop Dual Plane/Single Plane Manifold on 355

Post by immortality »

How does it compare to the dual manifold power curve? I would expect the single to maybe Rev a bit more but loos e a bit of low rpm torque.
User avatar
JBalsar
Posts: 10
Joined: Thu Aug 04, 2016 1:21 pm
cars: 1923 T Bucket
1928 Model A Pickup
1928 Model A Tudor
1968 HR Holden
2005 Holden SS Crewman

Re: Harrop Dual Plane/Single Plane Manifold on 355

Post by JBalsar »

Not sure. I do have a single plane. Think I might have to put it on and do another run. On the street this engine has no problem revving out to 6600rpm & feels like it pulls all the way. Different story with the load on the dyno tho.
Wade
Posts: 562
Joined: Mon Jul 11, 2016 6:29 am
cars: Vr 5.0 statesman vr exec 5.0 turbo vy clubsport

Re: Harrop Dual Plane/Single Plane Manifold on 355

Post by Wade »

The Harrop single plane is really good. Will pull hard in the top end. I had one on my turbo 5 litre. Didn’t notice much of a loss down low but I noticed the top end
Post Reply