Here We Go: My 383 Stroker Winter Project

[greg82255]

Re: Here We Go: My 383 Stroker Winter Project

The small ones are restrictive. Maybe you could use a dropped base K&N filter

looks like the shortest one here

http://www.knfilters.com/search/product.aspx?Prod=59-3214

vent adapters

http://www.knfilters.com/search/product.aspx?Prod=85-1350


K&N marine carbed area...double check for other sizes.

http://www.knfilters.com/marine/boats.htm

I think I'll probably just wait until the engine is back in the boat and I have raised the hatch as much as I can. That way I can figure out exactly how much height I have and how big of a flame arrestor I can buy.

http://teaguecustommarine.com/index...ts/powerflow-exhaust-manifolds-black-s-b.html

That link appears to just be the manifolds. The full kit with manifolds and risers is $1800.

Does anyone know anything about these? http://www.cpperformance.com/c-399-small-block-chevy.aspx
Apparently they offer a thru-transom version for $1100.

 

[joewithaboat]

Re: Here We Go: My 383 Stroker Winter Project

Does anyone know anything about these? http://www.cpperformance.com/c-399-small-block-chevy.aspx
Apparently they offer a thru-transom version for $1100.

Im reasonably sure those are for exposed engines only, meaning you can't have a hatch and enclosure. I would assume they would get very hot.

 

[greg82255]

Re: Here We Go: My 383 Stroker Winter Project

Im reasonably sure those are for exposed engines only, meaning you can't have a hatch and enclosure. I would assume they would get very hot.

That was my initial thought, but it also says they are water jacketed. I'm going to give them a call and see what the deal is.

 

[RogersJetboat454]

Re: Here We Go: My 383 Stroker Winter Project

Does anyone know anything about these? http://www.cpperformance.com/c-399-small-block-chevy.aspx
Apparently they offer a thru-transom version for $1100.

Those be bonafide jet boat headers (trust me, I know a bit about this ) They are not intended for use in a closed bilge. If they are the exact ones in the picture, they are not water jacketed. They are cooled by an internal mist of water coming from jets located in the tubes below the exhaust ports of the heads. There is what is called a Tee-valve that opens and closes to control the amount of water fed into the header jets. This valve opens more as the engine speeds up (more water pressure coming from the jet drive).

Installing these would pose several issues;

- Making the cooling system from a stern drive work like the cooling system of a jet boat.
- Making sure the water coming out of the nozzles is not being inhaled into the engine.
- Accepting the fact that since they are thin gauge tube steel, they are going to rust out QUICK being cooled by salt water.
- Accepting the fact that they will drip water into the bilge because they do have drains built in to allow excess water to drip out when the engine is shut off.
- Setting the boat on fire (there are times when the Tee-valve is pretty close to off, and the headers will start to heat up).

 

[greg82255]

Re: Here We Go: My 383 Stroker Winter Project

Those be bonafide jet boat headers (trust me, I know a bit about this ) They are not intended for use in a closed bilge. If they are the exact ones in the picture, they are not water jacketed. They are cooled by an internal mist of water coming from jets located in the tubes below the exhaust ports of the heads. There is what is called a Tee-valve that opens and closes to control the amount of water fed into the header jets. This valve opens more as the engine speeds up (more water pressure coming from the jet drive).

Installing these would pose several issues;

- Making the cooling system from a stern drive work like the cooling system of a jet boat.
- Making sure the water coming out of the nozzles is not being inhaled into the engine.
- Accepting the fact that since they are thin gauge tube steel, they are going to rust out QUICK being cooled by salt water.
- Accepting the fact that they will drip water into the bilge because they do have drains built in to allow excess water to drip out when the engine is shut off.
- Setting the boat on fire (there are times when the Tee-valve is pretty close to off, and the headers will start to heat up).

Thanks Erik for the detailed reply. In the description they did mention a Tee-valve so they are probably the exact headers you are talking about. I don't want to face any of those potential issues - guess I'll keep searching for something cheaper. BTW, I love your new picture

IMCO also makes a "thumper" system that is cheaper. Is it worth buying?

 

[RogersJetboat454]

Re: Here We Go: My 383 Stroker Winter Project

IMCO also makes a "thumper" system that is cheaper. Is it worth buying?

Have not heard anything about the IMCO manifolds. They look jacketed which is good. They say "light weight" which may mean they are aluminum, and may not live long in salt.

 

[joewithaboat]

Re: Here We Go: My 383 Stroker Winter Project

The Thumper has an optional hard anodize coating for use in salt water.

http://www.imcomarine.com/cal_store/thumper-power-small-block-manifold-riser-kit-black.html

These cost twice as much, must be more of an individual runner.

http://www.imcomarine.com/cal_store...w-small-block-manifold-and-a-riser-kit-3.html

If it were me i would hold out until budget allows or you can find a good set of used hiperf manifolds, that's if nothing is wrong with your stock ones.

 

[greg82255]

Re: Here We Go: My 383 Stroker Winter Project

The stock ones were brand new last year and there isn't anything wrong with them, so I'll plan to use them until I can find a great deal. I'm almost ready to start this thing up for the first time.

Erik - I actually was given an oil primer shaft by a friend of a friend who rebuilds engines. He had a few lying around. Thanks for the offer though!

 

[Tail_Gunner]

Re: Here We Go: My 383 Stroker Winter Project

Just a thought...there is very little to be gained with aftermarket marine exhaut systems when the engine itself does not turn beyond 5000 rpm. In fact that is the beauty of vortec heads in that they produce large tourqe and horse power at lower rpm..its a tumble design not swirl..swirl design need's high velocity or benefits from veloctiy its inherit by design

http://www.onedirt.com/tech-stories/engine/a-guide-to-vortec-vs-oe-small-block-chevy-heads/


http://www.enginebuildermag.com/Article/2497/making_a_big_splash_in_the_marine_market.aspx

At the conclusion of the cam tests, I installed a set of 74 cc Dart/World Products heads which I had done minor pocket porting on, with 2.02" and 1.60" valves. With the Cam Dynamics 278 still in the motor, and the Chevrolet high rise intake and Q-jet carb, horsepower jumped to 340 at 5000 rpm, and the fuel specifics went from .73 to .58.

The substitution of the 750 Holley marine carb added another 10 horsepower. Best yet, the horsepower at 3000 jumped from the stock 208, up to 223. A total of 44 runs was put on this little mouse during the thrash. I feel confident that optimizing this combination by decking the block or installing the marine .018" stainless head gaskets, and surfacing the cylinder heads to get the true compression up in the area of 9.5 to 9.75, advancing the cam a couple of degrees, and perhaps the addition of 1.6 rockers, carb jetting, timing adjustments, etc., and this combination would be good for 370 hp or better.

That's 100 hp over the stock engine with no bottom end changes. A well done 377 could make well over 400 hp, and the longer stroke would be a real kick in getting the boat on plane. Hydraulic roller cams offer the advantage of faster lift rates and higher lift for any given duration, which translates into a broader power band and improved overall performance. Although pricey, they are worth considering for the individual that wants the best.


http://www.boatheaders.com/headersperformance.htm

HEADER PERFORMANCE

Performance figures on headers very considerably. As a rule, the higher horsepower engines benefit more than lower horsepower engines. For example the 330 horsepower Mercury engine will gain approximately 75 to 100 RPM, where as the 365 horsepower Mercury engine will gain approximately 300 to 400 RPM (45 HP). Blown engines gain up to 800 RPM (80 to 100 HP).

But they do ad character and charm...

http://www.thirdgen.org/techboard/exhaust/338421-more-than-you-ever.html That will stunt your growth but its good stuff

 

[greg82255]

Re: Here We Go: My 383 Stroker Winter Project

Just a thought...there is very little to be gained with aftermarket marine exhaut systems when the engine itself does not turn beyond 5000 rpm. In fact that is the beauty of vortec heads in that they produce large tourqe and horse power at lower rpm..its a tumble design not swirl..swirl design need's high velocity or benefits from veloctiy its inherit by design

http://www.onedirt.com/tech-stories/engine/a-guide-to-vortec-vs-oe-small-block-chevy-heads/

http://www.enginebuildermag.com/Article/2497/making_a_big_splash_in_the_marine_market.aspx

At the conclusion of the cam tests, I installed a set of 74 cc Dart/World Products heads which I had done minor pocket porting on, with 2.02" and 1.60" valves. With the Cam Dynamics 278 still in the motor, and the Chevrolet high rise intake and Q-jet carb, horsepower jumped to 340 at 5000 rpm, and the fuel specifics went from .73 to .58.

The substitution of the 750 Holley marine carb added another 10 horsepower. Best yet, the horsepower at 3000 jumped from the stock 208, up to 223. A total of 44 runs was put on this little mouse during the thrash. I feel confident that optimizing this combination by decking the block or installing the marine .018" stainless head gaskets, and surfacing the cylinder heads to get the true compression up in the area of 9.5 to 9.75, advancing the cam a couple of degrees, and perhaps the addition of 1.6 rockers, carb jetting, timing adjustments, etc., and this combination would be good for 370 hp or better.

That's 100 hp over the stock engine with no bottom end changes. A well done 377 could make well over 400 hp, and the longer stroke would be a real kick in getting the boat on plane. Hydraulic roller cams offer the advantage of faster lift rates and higher lift for any given duration, which translates into a broader power band and improved overall performance. Although pricey, they are worth considering for the individual that wants the best.


http://www.boatheaders.com/headersperformance.htm

HEADER PERFORMANCE

Performance figures on headers very considerably. As a rule, the higher horsepower engines benefit more than lower horsepower engines. For example the 330 horsepower Mercury engine will gain approximately 75 to 100 RPM, where as the 365 horsepower Mercury engine will gain approximately 300 to 400 RPM (45 HP). Blown engines gain up to 800 RPM (80 to 100 HP).

But they do ad character and charm...

http://www.thirdgen.org/techboard/exhaust/338421-more-than-you-ever.html That will stunt your growth but its good stuff

All of this information is very interesting -thank you. I think I'm going keep looking on ebay and craigslist until something good comes up. There's actually a boat show coming up in 2 weeks here in Boston and they may have some kind of show deals there - who knows.

 

[joewithaboat]

Re: Here We Go: My 383 Stroker Winter Project

Just a thought...there is very little to be gained with aftermarket marine exhaut systems when the engine itself does not turn beyond 5000 rpm. In fact that is the beauty of vortec heads in that they produce large tourqe and horse power at lower rpm..its a tumble design not swirl..swirl design need's high velocity or benefits from veloctiy its inherit by design

http://www.onedirt.com/tech-stories/engine/a-guide-to-vortec-vs-oe-small-block-chevy-heads/


http://www.enginebuildermag.com/Article/2497/making_a_big_splash_in_the_marine_market.aspx

At the conclusion of the cam tests, I installed a set of 74 cc Dart/World Products heads which I had done minor pocket porting on, with 2.02" and 1.60" valves. With the Cam Dynamics 278 still in the motor, and the Chevrolet high rise intake and Q-jet carb, horsepower jumped to 340 at 5000 rpm, and the fuel specifics went from .73 to .58.

The substitution of the 750 Holley marine carb added another 10 horsepower. Best yet, the horsepower at 3000 jumped from the stock 208, up to 223. A total of 44 runs was put on this little mouse during the thrash. I feel confident that optimizing this combination by decking the block or installing the marine .018" stainless head gaskets, and surfacing the cylinder heads to get the true compression up in the area of 9.5 to 9.75, advancing the cam a couple of degrees, and perhaps the addition of 1.6 rockers, carb jetting, timing adjustments, etc., and this combination would be good for 370 hp or better.

That's 100 hp over the stock engine with no bottom end changes. A well done 377 could make well over 400 hp, and the longer stroke would be a real kick in getting the boat on plane. Hydraulic roller cams offer the advantage of faster lift rates and higher lift for any given duration, which translates into a broader power band and improved overall performance. Although pricey, they are worth considering for the individual that wants the best.


http://www.boatheaders.com/headersperformance.htm

HEADER PERFORMANCE

Performance figures on headers very considerably. As a rule, the higher horsepower engines benefit more than lower horsepower engines. For example the 330 horsepower Mercury engine will gain approximately 75 to 100 RPM, where as the 365 horsepower Mercury engine will gain approximately 300 to 400 RPM (45 HP). Blown engines gain up to 800 RPM (80 to 100 HP).

But they do ad character and charm...

http://www.thirdgen.org/techboard/exhaust/338421-more-than-you-ever.html That will stunt your growth but its good stuff

I didn't read through all of these links but are you are trying to say that a 400+hp small block doesn't need or won't benefit from free flowing exhaust ???? :facepalm:

 

[Tail_Gunner]

Re: Here We Go: My 383 Stroker Winter Project

http://www.offshoreonly.com/forums/...nifolds-please-learn-my-expensive-lesson.html

If your stock manifolds are at end of life or damaged then the aftermarket manifolds will in many cases be at equal or sometimes lower cost than the OEM manifold and riser replacements. It is also advisable and a benefit for reliability to replace these exhaust manifolds with the new dry riser joint type manifolds and eliminate the wet water passage and gasket joints between the base manifold and riser where engine destroying leaks and corrosion can and do occur.
In summary here, don't expect most replacement short runner single riser manifold systems to add any real measurable power on stock engines and even on higher horsepower 400-500HP marine engines the gains may only be in the 15-20HP range which will net a very small or almost unmeasurable increase in boat performance.

Bottom line- Don't call marine short runner manifolds HEADERS! and when considering replacing exhaust systems on your boats try to find test data and actual performance boater results form independant sources and don't rely on manufacturers or distributor claims to make your $2500-$5000 exhaust system expenditures if you work on a budget and expect measurable results for the purchase!
I will receive a lot of flack for this post from varing sources and a lot of so called marine exhaust experts, but I have done a great deal of independant testing and evaluation on marine exhaust upgrades on V-8 marine engines between 300-700 HP in general as have others on OSO like Bob at Full Throttle and and many good marine engine builders. Most of us will say that a good true header or header manifold system will add some good measurable power increases. Do exhaust upgrades always translate to increased boat performance, Heck NO! That increase will depend on many variables and that's a choice for you as the boat owner and money supplier to make and substantiate.
Please also remember that all the other factors of hull form, type,size, weight, setup and drive and prop efficiences will also greatly affect the performance gains seen from exhaust upgrades.
Investigate header and manifold exhaust systems carefully and determine what you will accept and need in performance gains, then buy and spend accordingly.




Note the poster....With all of that i will say if that engine was setup up to spin at 7000 yes aftermarket exhasut would be of a benefit...and a expensive benefit

 

[joewithaboat]

Re: Here We Go: My 383 Stroker Winter Project

I think that most would agree that with the o/p's overall combination the weakest link in the air pump(engine) is the exhaust manifolds. Every engine combination is different of course. Stock engines that have an optimal part combination don't need high flow exhaust. However this engine is not stock, every part in this engine which controls the pumping of air has been changed with the exception of the exhaust.
Stay the course Greg, you will turn up a good used set eventually. Mercruiser doesn't put high flow exhaust on their high output big blocks because it looks pretty and saves them money.

Id take a 20 hp gain any day, if thats all it was, when tweaking a hopped up engine. Never mind the fact that if you go aluminum you get the weight savings.

 

[Tail_Gunner]

Re: Here We Go: My 383 Stroker Winter Project

Joe i am not by any means doubting you....you have given very concise info but as to header's on marine engines and wet exhaust...Its a game for kings...Notice where the yeilds come from in a perfect world...not water jacketed marine exhasut

http://forum.grumpysperformance.com/viewtopic.php?f=56&t=3529

 

[greg82255]

Re: Here We Go: My 383 Stroker Winter Project

Joe i am not by any means doubting you....you have given very concise info but as to header's on marine engines and wet exhaust...Its a game for kings...Notice where the yeilds come from in a perfect world...not water jacketed marine exhasut

http://forum.grumpysperformance.com/viewtopic.php?f=56&t=3529

CMI's website seems to indicate that their headers will add a considerable amount of power and torque... They show some dyno data with their E-top headers compared to the standard mercury manifolds on a 383.

http://www.custommarine.com/headerapps/dyno_data.php

 

[joewithaboat]

Re: Here We Go: My 383 Stroker Winter Project

Joe i am not by any means doubting you....you have given very concise info but as to header's on marine engines and wet exhaust...Its a game for kings...Notice where the yeilds come from in a perfect world...not water jacketed marine exhasut

http://forum.grumpysperformance.com/viewtopic.php?f=56&t=3529

Tail gunner,

I'm not clear as to what your driving at....
You say that its not worth changing the stock exhausts and then post dyno sheets that clearly show gains from doing so?

The stock, non separated runner, log type exhaust are terrible at flow and scavenging...
are you trying to compare them to small 1 1/2 inch primary headers as a baseline for which to determine that upgrades are or are not worth doing?

This is an article i found interesting. In the first part of it with a stock 500 hour engine they add almost 15mph to an ordinary small block powered boat with heads, intake, carb, ignition, exhaust and a prop change. All easy to do and shows how typical hot rod principals can work even on the water. I get tired of hearing that typical car mods don't work on the water.

http://www.rlcpe.com/images/projects/tripple_digits/project_trippledigits.html

I agree that some mods cost more than others and that "Good" exhaust costs much more than other things you can get gains from but for this engine exhaust is probably the next thing that would show some good gains. Imco power flows, which i think is what Greg is looking for, have a solid history online for increasing top speed with only an exhaust change. Some only see 1 mph but some see 5 mph on completely stock equipment.

Here is a real world test for GLM brand that have a somewhat divided runner. Its a 2 mph gain on a bone stock 350 merc. I would expect Imco's could possibly gain even more.

http://www.glmmarine.com/manifolds/images/ads/fpboating_0203.pdf

 

[Scott Danforth]

Re: Here We Go: My 383 Stroker Winter Project

exhaust discussions aside, how is the progress going? cant wait until there is a video of the startup.

 

[greg82255]

Re: Here We Go: My 383 Stroker Winter Project

exhaust discussions aside, how is the progress going? cant wait until there is a video of the startup.

Unfortunately I am back in school for the spring semester and am not able to work on the engine that much right now. I get to come home for a day or 2 every few weeks. I have a week off in March and I plan to finish up the project then. If all goes well and I get it running, I'll hopefully even get it into the boat that week.

 

[greg82255]

Re: Here We Go: My 383 Stroker Winter Project

It's finally time for my March break - I've already gotten back on the motor and intend to get it started early this week. If all goes well I may even get it in the boat too. As for the previous topic of discussion - exhaust - I have still not decided what to do yet. I put the original manifolds and risers on there just to do the test run/break in and I'll re evaluate later. I have a few questions that I need to address before I start it up:

1. I oil primed the motor yesterday. How long will it stay primed, and should I prime it again before I start it? It will be in the next 2-3 days.
2. I need to find a wiring diagram that shows how to wire the motor for running on the stand. Does anyone have access to one that can be posted? If not, if someone could explain how to do it that would be great. I bought one of those remote starter switches also.
3. Once I get it running, how long to run it and at what RPM? I vaguely remember the builder telling me to run it at 2000 rpm for 30 minutes, but I intend to call him again to go over exactly what to do.

I have some pictures that will go up today.

 

[greg82255]

Re: Here We Go: My 383 Stroker Winter Project

Here are some pictures. It's almost ready to go, just needs some fuel, wiring and a few minor details: