Older stainless Marine exhaust
 

I bought 2 sets of the older SM exhaust with alum. risors, to replace my stock cast iron exhaust. Would have prefered Gils, but the price was right. ;) These manifolds are basically the same design as the stock manifilds: open manifolds, no dividers.
I'm expecting zero performance gains, which is fine. Reasoning for the change is to eliminate 160# , and eliminate the chance of the leaky risor to manifold gasket.

Is there any reason not to use these? Motors will never be modified. 502MPI's

Re: Older stainless Marine exhaust
 

Call Brownie@SM if he doesn't chime in for your answer.

Re: Older stainless Marine exhaust
 

So, there are no problems/issues with these manifolds, or nobody knows squat about them? ;)

Re: Older stainless Marine exhaust
 

Those aluminum risers CANNOT be used on a high performance engine. They are cylindrical (no nozzle) and will hoover water at idle. Great and long lasting for STOCK engines with non-lumpy cams.

Re: Older stainless Marine exhaust
 

Brownie, thanks. I assume they are fine for my stock 502 MPI's then.

Re: Older stainless Marine exhaust
 

Chit! I didn't realize that these two messages were from the same guy. No! Don't use these risers on that engine. I recommend long risers for the 502 MPI. Call me at 305-681-7892 for more info.

Re: Older stainless Marine exhaust
 

Brownie, tried to call, but no answer.

Guess I'm not following here. They would seem like a direct replacement for what I have, stock cast iron merc exhaust with silent choice. I understand that longer risors are preferred, but everyone has short risors for use of silent choice on BBC's. I must not be seeing the whole picture.

Will try to get ahold of you Wed morning to talk in detail.
Thanks,
Jerry

Re: Older stainless Marine exhaust
 

The difference is backpressure. Ours (or anybody elses besides Merc) are free flowing. Freeflowing = larger area. Same amount of gas, larger area = lower gas velocity. Low gas velocity can't push the cooling water as far. Your engine is a high performance engine. If you want a performance manifold on it, you will be forced to use either a longer or a nozzled riser. My cellphone: 305-332-7611.

Re: Older stainless Marine exhaust
 

A reminder to search your stash for 2 sets of take offs in case I prefer to go that route. Thanks Brownie for the phone call.