surmirage

I have a 502 block stroked to 540ci with stock heads(502ci). Xtreme cam (CCA-01-456-8) with air gap dual plane intake and 850cfm carb. Stock 7.4 mpi exhaust silence choice. (exhaust upgrade on its way) Baja H2X 24' with bravo 1.5 gears running 28 p 4b non lab.

First test so far: 69.4mph gps @ 4600 rpm. Spark plug color good.

I know that removing the restrictive stock exhaust and switching to a stainless marine hi-torque would free up 250rpm and labbing the prop another 150 rpm. But for now if I switch to an single plane intake would it help bring the rpm up 200rpm or more?
Thanks in advance

pslonaker

iTrader: (1)

If your motor is a 7.4...you might want to rethink adding more RPM to it because all the internals are cast. 4600 RPM is almost at the top of its game and turning it more it going to possibly toss a rod out of it somewhere, which will totally screw up your day.

goebel1

iTrader: (2)

When I went to a single plane and domennator I gain 6mph.

surmirage

How much rpm did you gain?

ezstriper

a single plane would help on mid to top end still need to dial in prop after to get correct RPM but also keep in mind the restrictions of the baja hull

goebel1

iTrader: (2)

Bob at Marine Kinetics (awsome guy) had me go from a 850cfm carb to a 1050 Domenator and I maded dyno 700 +hp on pump gas. My 540 ran good with the 850 just would not pull on top end when I change over to the Domenator she came alive on the top end. I gain right at 3-4000 rpms. I spin my 540ci to 6200RPM.

88Fountain

iTrader: (1)

When my boat had 454 mag's in it, I gained 600-700 rpm going from the exhaust manifolds to emi thunder manifolds. My boat also had the silent choice on it at that time. I would think a good exhaust on a 540 would make a substantial difference over manifolds. I do know that on my 540's going from imco powerflow manifolds to emi headers, I saw no performance change.

surmirage

Thanks guys,
you convinced me, first single plane with dominator and then exhaust.

Griff

The stock exhaust is killing your power and choking your engine. I don't see a reason to change the intake and carb to fix the exhaust restriction. The stock exhaust is restrictive on a stock 502 and I would bet you see more than a 250rpm gain by changing it.

baja27

goebl1 when you switched over to a dominator did your cruising suffer as in economy?