Stroker engine build

Returntrip

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Happy New year everybody. Does anyone have any input about using 6" connecting rods on a sbc stroker build? Also possibly going to run an aluminum head under heavy torque loads? will be closed cooling system. Thanks for any input.
 

Bondo

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Ayuh,..... The 6" rod puts the wrist pin up under the rings,......

Stick with the 5.7 rods,....
 

Scott Danforth

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Get a complete SCAT rotating assembly with KB D-dish pistons and stick with iron heads

Dont overthink the proven kits
 

Returntrip

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Happy New year everybody. Does anyone have any input about using 6" connecting rods on a sbc stroker build? Also possibly going to run an aluminum head under heavy torque loads? will be closed cooling system. Thanks for any input.
Ayuh,..... The 6" rod puts the wrist pin up under the rings,......

Stick with the 5.7 rods,....
I did stick with my initial thoughts & bought Scat forged & somewhat cleeranced "I" beam rods. I will most likely be putting Mahle forged coated pistons on top of them. Im shooting for around 9.2 compression, do you think thats a safe range or should I be closer to 9.0? Still trying to spec out a cam, trying to figure out LSA & duration. Thinking something like 114 on LSA & have no idea on duration, Im thinking less duration would be better. Thanks for confirming my initial thoughts on the rods.
Scott has good advice to stick with a complete rotating assembly, if I didnt already have a $1000 crank I would have gone that route. Next time (If I even had a crank) I would take his advice. So many variables in a gas job build. DIESELS ARE SO MUCH EASIER! LOL . Any input on roller cam specs would be appreciated, thanks guys.
 

Scott06

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I did stick with my initial thoughts & bought Scat forged & somewhat cleeranced "I" beam rods. I will most likely be putting Mahle forged coated pistons on top of them. Im shooting for around 9.2 compression, do you think thats a safe range or should I be closer to 9.0? Still trying to spec out a cam, trying to figure out LSA & duration. Thinking something like 114 on LSA & have no idea on duration, Im thinking less duration would be better. Thanks for confirming my initial thoughts on the rods.
Scott has good advice to stick with a complete rotating assembly, if I didnt already have a $1000 crank I would have gone that route. Next time (If I even had a crank) I would take his advice. So many variables in a gas job build. DIESELS ARE SO MUCH EASIER! LOL . Any input on roller cam specs would be appreciated, thanks guys.
You’ll be fine with9.2 compression. Stock was 9.4 and works on 87 octane.
 

Scott Danforth

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I did stick with my initial thoughts & bought Scat forged & somewhat cleeranced "I" beam rods. I will most likely be putting Mahle forged coated pistons on top of them. Im shooting for around 9.2 compression, do you think thats a safe range or should I be closer to 9.0? Still trying to spec out a cam, trying to figure out LSA & duration. Thinking something like 114 on LSA & have no idea on duration, Im thinking less duration would be better. Thanks for confirming my initial thoughts on the rods.
Scott has good advice to stick with a complete rotating assembly, if I didnt already have a $1000 crank I would have gone that route. Next time (If I even had a crank) I would take his advice. So many variables in a gas job build. DIESELS ARE SO MUCH EASIER! LOL . Any input on roller cam specs would be appreciated, thanks guys.
I would shoot for 9.5:1 or less. as Scott stated, stock motor was 9.4:1

vortec heads allow you to run slightly higher compression than the combustion chambers prior

with wet exhaust, stick to 270 degrees of duration of less with wet exhaust. or you need to go to a dry jacketed exhaust. reversion kills motors

I would probably go with this https://www.compcams.com/xtreme-marine-212-218-hydraulic-roller-cam-for-chevrolet-small-block.html

this is max with wet exhaust https://www.compcams.com/xtreme-marine-218-224-hydraulic-roller-cam-for-chevrolet-small-block.html
 

Returntrip

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Get a complete SCAT rotating assembly with KB D-dish pistons and stick with iron heads

Dont overthink the proven kits
I would shoot for 9.5:1 or less. as Scott stated, stock motor was 9.4:1

vortec heads allow you to run slightly higher compression than the combustion chambers prior

with wet exhaust, stick to 270 degrees of duration of less with wet exhaust. or you need to go to a dry jacketed exhaust. reversion kills motors

I would probably go with this https://www.compcams.com/xtreme-marine-212-218-hydraulic-roller-cam-for-chevrolet-small-block.html

this is max with wet exhaust https://www.compcams.com/xtreme-marine-218-224-hydraulic-roller-cam-for-chevrolet-small-block.html
Thanks for the input. Im a little confused on dry jacketed exhaust? I will be using factory Mercruiser manifolds with added closed cooling system, Im assuming that is not dry jacketed exhaust...Ill check out the cams.
I am very tempted to make another boat purchase, A 24ft. Rogue just showed up at the boat donation center in really, really nice shape, $1,400.00
 

Scott Danforth

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Thanks for the input. Im a little confused on dry jacketed exhaust? I will be using factory Mercruiser manifolds with added closed cooling system, Im assuming that is not dry jacketed exhaust...Ill check out the cams.
I am very tempted to make another boat purchase, A 24ft. Rogue just showed up at the boat donation center in really, really nice shape, $1,400.00
the rogue would be a nice boat....:D...... however you will most likely need to rebuild the transom, rear foam boxes and, bulkhead just forward of the motor and the stringers in between.
 

Returntrip

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the rogue would be a nice boat....:D...... however you will most likely need to rebuild the transom, rear foam boxes and, bulkhead just forward of the motor and the stringers in between.
I'll check it out, thanks. I've had my share of glass work & dont much care to do it anymore, especially in New England weather.
 

Scott06

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Thanks for the input. Im a little confused on dry jacketed exhaust? I will be using factory Mercruiser manifolds with added closed cooling system, Im assuming that is not dry jacketed exhaust...Ill check out the cams.
I am very tempted to make another boat purchase, A 24ft. Rogue just showed up at the boat donation center in really, really nice shape, $1,400.00
Factory mercruiser exhaust is a wet system. Water is introduced to the exhaust gases after the elbows on top of the manifolds. If you have a bigger (aka longer duration and overlap) cam you'll suck water into the combustion chambers.

High performance/boderline racing engines will use a dry exhaust like shown here -https://www.hardin-marine.com/c-1103-dry-offshore.aspx they are dry (no water mixed in to cool exhaust)- jacketed until the very end to keep reversion from pulling water into the combustion chambers. Stick with the cams scott suggests or similar duration /Lobe separation to avoid this issue. Here is a article and video about it.https://www.hardin-marine.com/t-what_is_exhaust_reversion.aspx
 

Scott Danforth

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I'll check it out, thanks. I've had my share of glass work & dont much care to do it anymore, especially in New England weather.
then find a boat newer than 15 years old.

I have slow speed video of the cam on my BBC pulling in water vapor from 12 feet behind the collector. I had to go with a custom H-pipe and water-jacketed exhaust in order to run my mufflers.
 

Returntrip

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Factory mercruiser exhaust is a wet system. Water is introduced to the exhaust gases after the elbows on top of the manifolds. If you have a bigger (aka longer duration and overlap) cam you'll suck water into the combustion chambers.

High performance/boderline racing engines will use a dry exhaust like shown here -https://www.hardin-marine.com/c-1103-dry-offshore.aspx they are dry (no water mixed in to cool exhaust)- jacketed until the very end to keep reversion from pulling water into the combustion chambers. Stick with the cams scott suggests or similar duration /Lobe separation to avoid this issue. Here is a article and video about it.https://www.hardin-marine.com/t-what_is_exhaust_reversion.aspx
Thanks for that info Scott. Yes I knew about the reversion end of it but was reading conflicting articles about the LSA and duration. I was trying to keep my torque curve at the lowest RPM range, but obviously after hearing from you guys the reversion end of it far outways the minimal torque gain/loss. I understand that duration helps to scavenge gases from the cylinders. I would rather lose a very little(torque) than lose a lot (engine).
My build definitely doesnt warrant a dry jacketed exhaust system nor is it being built strictly for performance. Believe me I love scaring myself, but also need to get to work with my boat also. Thanks guys.
 

Returntrip

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Gotcha on the boat buy year. If you dont mind me asking...what is a collector on your exhaust & how can it be pulling water from 12' away on a boat your size? Wouldnt that pulling zone be far beyond the transom of your boat? Is the use of the mufflers to keep it that much quieter? Sorrry about the questions, just like to learn from people who know a lot more about this stuff than me.
 

Scott Danforth

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the videos were with 18" long elbows. at about 750 RPM, there was enough vacuum during the overlap cycle to pull the water vapor back in. it filled the exhaust manifolds up with water, just idling on the crate. I went with side exit exhaust. since I could no-longer use the captains call diverters, I installed mufflers to keep the wife happy.

here is the exhaust I built to handle reversion. https://forums.iboats.com/threads/bbc-build-dont-tell-the-admiral.666775/page-15#post-4955890

here is a pic installed
0106201924_resized-jpg.308066


back behind the bulkhead are the mufflers going to the side exhaust
1109191425a_resized-jpg.305407
 

Returntrip

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the videos were with 18" long elbows. at about 750 RPM, there was enough vacuum during the overlap cycle to pull the water vapor back in. it filled the exhaust manifolds up with water, just idling on the crate. I went with side exit exhaust. since I could no-longer use the captains call diverters, I installed mufflers to keep the wife happy.

here is the exhaust I built to handle reversion. https://forums.iboats.com/threads/bbc-build-dont-tell-the-admiral.666775/page-15#post-4955890

here is a pic installed
0106201924_resized-jpg.308066


back behind the bulkhead are the mufflers going to the side exhaust
1109191425a_resized-jpg.305407
Wow!!!! What an awesome engine compartment! Did the Rogue come with a nice big opening like that? Or did you FAB work to floor? Great to see a Big Block in there too, that’s the way to go. The exhaust work looks amazing too. Do you have the capability to Tig stainless & where do you get the elbows & pipe? Great work!
 

Scott Danforth

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Wow!!!! What an awesome engine compartment! Did the Rogue come with a nice big opening like that? Or did you FAB work to floor? Great to see a Big Block in there too, that’s the way to go. The exhaust work looks amazing too. Do you have the capability to Tig stainless & where do you get the elbows & pipe? Great work!
The bilge is stock. Not quite enough room for twins

I work with a group of fantastic welders. I did the design and fitup.

Hit the thread in my sig and look at post #1 for all related threads

Only the 24' Rogues with the VP drives came with a small block. A 454/bravo 1 or a 460/ cobra were the other packages

So now back to your build.
 

Returntrip

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The bilge is stock. Not quite enough room for twins

I work with a group of fantastic welders. I did the design and fitup.

Hit the thread in my sig and look at post #1 for all related threads

Only the 24' Rogues with the VP drives came with a small block. A 454/bravo 1 or a 460/ cobra were the other packages

So now back to your build.
I have to say, i have used your "Enzo" quote many times, Love to see it & I like to live by it. I only work on Diesels, but love to hammer the gas!! Now I"ll stop blabbing
 

Returntrip

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The bilge is stock. Not quite enough room for twins

I work with a group of fantastic welders. I did the design and fitup.

Hit the thread in my sig and look at post #1 for all related threads

Only the 24' Rogues with the VP drives came with a small block. A 454/bravo 1 or a 460/ cobra were the other packages

So now back to your build.
What do you think about block deck height? should i zero deck it or leave the pistons in the jug a little & use thinner head gaskets? And what type of composition or material is good for gas marine engines???
 
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