Exhaust manifold risers

[Bvc]

Are the exhaust manifold risers the same from a 4.3 L V6 to a 5.7 L V8 and are the manifolds and risers different from a Mercruiser to a Volvo Penta

 

[harringtondav]

Go to marineengine.com or another online parts catalog. I think the answer is no between engine sizes.

 

[achris]

Yes, same elbows between V6 and V8s of the same era on mercruiser. Yes, Volvo and Mercruiser manifolds and elbows are different.

Chris....

 

[harringtondav]

Yes, same elbows between V6 and V8s of the same era on mercruiser. Yes, Volvo and Mercruiser manifolds and elbows are different.

Chris....

Another bzzrrt for me. How does Merc make up for the difference in engine length?

 

[Bvc]

If I had to guess probably just longer in the front for two more cylinders I was told by a boat engine builder just to put a V8 in instead of that 4.3 direct swap as far as bolting into place

 

[achris]

...How does Merc make up for the difference in engine length?

Brilliantly!



The V6 'pulls' back, the V8 doesn't.

Chris...........

 

[achris]

If I had to guess probably just longer in the front for two more cylinders I was told by a boat engine builder just to put a V8 in instead of that 4.3 direct swap as far as bolting into place

The engine side mount pads need to be further forward (by about 4") for the V8, or long enough to support both/either engines.

Like this.....



Chris........

 

[Bondo]

Are the exhaust manifold risers the same from a 4.3 L V6 to a 5.7 L V8

Ayuh,..... Welcome Aboard,..... They maybe the same, or maybe different,....
Depends on the vintages, 'n whether 3" dumps, or 4" dumps,......

and are the manifolds and risers different from a Mercruiser to a Volvo Penta

Ayuh,..... Quite different,....
Accessory mountin' holes are different 'tween 'em, as well as possibly the dump diameters, 'n angles of fall,....
'n Lengths of the risers/ elbows,.....

'ell,.... OMC used 3, 1/2" dumps on some motors, rather than the Merc standard of 3", Or 4",.....

 

[Bvc]

Thank you very much I'll stay away from the Volvo Penta I did look up part numbers and I saw the risers are the same part number for the V6 or the V8

 

[Bvc]

I guess I'm going to have to put the block down in there and double check on the motor mounts I know my pads aren't big enough to move them up and boat engine builder said they will just bought right in and it's place

 

[achris]

Chris........

 

[Bvc]

Okay thank you again but let me ask so as far as the exhaust I see that the V8 one doesn't have a tight as angle is that all made up with the Bellows or do I have to buy a different part in there to make up for that

 

[Bvc]

I see you have to move the motor mounts for and a half inch forward give or take

 

[achris]

I see you have to move the motor mounts for and a half inch forward give or take

Four and a half inches exactly.

 

[harringtondav]

Okay thank you again but let me ask so as far as the exhaust I see that the V8 one doesn't have a tight as angle is that all made up with the Bellows or do I have to buy a different part in there to make up for that

So I'm getting a little brave with new info, but achris 's diagrams show different elbows on the V8. And the exhaust rubber tubes won't make up for the difference from V6 elbows. Check the p/n on V8 & V6 tubes. Guessing they are the same.

 

[achris]

So I'm getting a little brave with new info, but achris 's diagrams show different elbows on the V8. And the exhaust rubber tubes won't make up for the difference from V6 elbows. Check the p/n on V8 & V6 tubes. Guessing they are the same.

harringtondav

For the same era exhaust system.. Lets' use early 90's to the start of the 'dry joints' as an example... Starting at the engine and working downstream.... (item numbers correspond to numbers on the drawing)
1. Manifolds are (obviously) different, -87114A19-V8/-99746A8-V6.
2. Cast iron elbows are the same, -807914A1.
3. Upper rubber tube is the same, 32-44348T.
4. Aluminium elbow is different, -11086T-V8/-14478T-V6.
5. Lower rubber tube is the same, 32-14358T.
6. Y-pipe is the same, -807130A4.

Same rules apply to earlier and later (dry-joint) exhaust systems...

Chris......

 

[Bvc]

I don't know I was wondering that too I know the risers are the same from V8 to V6 I haven't got a chance to look if there was different part numbers for the tubes or the Bellows after that unless somebody can answer that off the top of their head

 

[Rick Stephens]

Only thing different is the elbows and manifolds. And 4.5 inches further towards the bow for the motor mounts.