383 piston cc and compression

[Yukonmuscle]

I haven't posted in a while, but been reading a lot every day. I've been toying with ideas on making my boat a little faster, fuel, intake, ignition..... (2010 5.0l tks, 162 ratio alpha) But everyone here seemed to think all my mods would not get me what i wanted. And after researching you guys are right. After reading the ongoing 383 build, I decided what the hell ill build one on a budget, picking up pieces, slow as I go, looking for sales, and used parts. I have a buddy that runs a machine shop and he said its a couple hundred to clean block, bore cyl and deck head surface, hes gonna clearance and assemble for free so this shouldn't be too bad.

A 91 Chevy truck dontated it's short block inc pan and timing cover $0 from a friend
Eagle cast stroker crank, $230
Scat 5.7 rods $255
Comp xm270hr cam. $350

The peices are slowly coming together but I'm having issues picking a piston. I don't know what heads I'm running yet but i do know i would like to run a 64 cc chambered head. (seems easiest to find used). When I put my numbers into different compression calculators I'm being shown like 5.6cr with 18cc dish pistons, 64 cc head and .045 headgaskets??? What gives? Every thing I've read says a deep dish is needed to run 64cc heads?

Can someone point me to a good calculator I can run on an iPhone, tell me what I may be doing wrong, or offer advise on a piston? I cant seem to find the piston size in the on going 383 thread. I have a hundred other questions as I go but I'll ask as I need I guess.
Thanks
Oh and I'd just like to thank every one on the forum for turning a simple 2 - 4 barrell carb and intake swap into a full engine build lol. I love going fast but my wallet hates it lol

 

[Bondo]

Re: 383 piston cc and compression

I don't know what heads I'm running yet but i do know i would like to run a 64 cc chambered head. (seems easiest to find used). When I put my numbers into different compression calculators I'm being shown like 5.6cr with 18cc dish pistons, 64 cc head and .045 headgaskets??? What gives? Every thing I've read says a deep dish is needed to run 64cc heads?

Ayuh,... Pickin' the heads is Easy,.... Vortecs,....

Then get the block decked to 0.00"....
With yer .040odd" headgasket, you can get the quench that makes the Vortec heads do their thing....
With a zero decked block, run yer compression numbers...
Then pick the piston D-dish that gives ya 'bout 9:1 ratio.... just keep it under 10:1....

The Best spent money possible in this plan of yer's is, have the complete rotating assembly Balanced....
'course, that's later on,.....

 

[Tail_Gunner]

Re: 383 piston cc and compression

Ayuh,... Pickin' the heads is Easy,.... Vortecs,....

Then get the block decked to 0.00"....
With yer .040odd" headgasket, you can get the quench that makes the Vortec heads do their thing....
With a zero decked block, run yer compression numbers...
Then pick the piston D-dish that gives ya 'bout 9:1 ratio.... just keep it under 10:1....

The Best spent money possible in this plan of yer's is, have the complete rotating assembly Balanced....
'course, that's later on,.....

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=4081 as above but in great deatail..have a read

 

[John_S]

Re: 383 piston cc and compression

Hard to beat those vortecs, even when the cam requires machining the heads for the extra lift, new springs, and possibly screw-in studs. If you have been watching the 383 thread, you already know that.

Just wondering what your top speed in the 195/5.0L was, and what you are shooting for with the 383?


PS: I have a couple of links to decent comp ratio calculators. I'll post tonight. You will need an old fashioned internet browser though. they are not iphone apps.

 

[Yukonmuscle]

Re: 383 piston cc and compression

Thanks for the link, I'll give a look over. I was turning a 21 pitch to 4700 rpm, 54mph with a days running gear, food drinks and 3 people. Pretty good I thought. I'm hoping to hit a mid 60 number, 65 being the goal. Sleeper 195 lol.

I like the performance of the vortec heads, but I'm looking at aluminum heads for sure. So far I've been looking at gmpp heads, darts and tfs heads. All 202/160 valved and all around 180cc intake volume.

 

[PBarrett]

Re: 383 piston cc and compression

Here you go.

http://www.kb-silvolite.com/calc.php?action=comp
http://www.kb-silvolite.com/calc.php?action=comp2

More interesting reading.
http://www.kb-silvolite.com/article.php?action=read&A_id=36
http://www.hotrod.com/techarticles/engine/how_to_calculate_compression_ratio/

 

[John_S]

Re: 383 piston cc and compression

Yea, I'd say that is pretty good. If it was gps, then rpms maybe reading a little low (ie the slip number was very low).

Anyway, sounds like you are building a boat to beat Greg. trying to double your current hp?

With all that induction breathing potential, I assume you will be running up in the 5500rpm area, and looking for a much better exhaust.

 

[Yukonmuscle]

Re: 383 piston cc and compression

Yeah gps was used. Speedo on boat always seems to be reading 5 mph faster then I'm actually going. I'd like to spin 5500 rpm, just have to figure out what I have to do to by pass the boats revlimiter at 4950.

And I'm keeping my eyes open for a decent higher flowing marine exhaust.

 

[billbayliner]

Re: 383 piston cc and compression

I found Grumpys Garage being referred to here. It may interest you.
http://www.marineengine.com/boat-fo...4668-V6-to-V8-engine-swap&p=370387#post370387

Yukonmuscle, here is a static C/R calculator.
http://cleanandsober.741.com/CompressionCalculator.html
If you plug in 1 for inches, plug in 4.030 for bore, plug in 3.750 for stroke, plug in 4.030 for head gasket bore, throw in .022 for compressed head gasket thickness, throw in 64 for combustion chamber volume, use a negative sign in front of piston dish volume (- 18), and throw in .016 for deck (this gives you .038" squish or quench number) and you'll come up with 10.871000931238503 to 1
If this is a full dished piston, there will be no quench area.

Now add a deck to the piston (D-dish or L/C Quench for example), and increase the dish volume to -26. Now you'll come up with a quench area and a 10.068530685156098 to 1 C/R.

With a good quench the C/R can be slightly more than with no quench at all.

I read where many suggest no 6" rods and no short piston skirts, although that would seem to make sense for hot rod use, but does not for Marine. We're not turning high RPM so there is no need to build for street use.
I read where the 5.7" rods keep the pins down and skirts longer and ring landings where they need to be. So the 5.7" rods would be a good choice.

It would be helpful to read Dennis Moore's Small Block Chevy Marine Performance. Also read some of the articles by Jeff Smith on Quench or Squish. Jeff is an automotive guy but this principle particularly applies to the SBC marine motor.

I'd use caution taking the advice from the automotive guys. They know how to build these street motors, but they usually have no marine cruiser experience and typically aren't up to speed on marine loads or marine load detonation.

 

[greg82255]

Re: 383 piston cc and compression

Just to throw it out there - As you have probably seen in my thread, I bought a set of vortec cores ($300). Then I had them baked and blasted, magnafluxed, resurfaced, 3-angle valve job, stainless valves, upgraded springs, hardened retainers, and had them assembled. That all cost about $550. Then I started to hear about screw-in studs. I then took the heads apart myself and brought them to another shop, where I had the stud bosses machined .050" and had the holes tapped and ARP studs installed. Then I had them assembled again because I messed up which shims went where. That was another $400. For the price I paid ($1250 total) I could have basically bought a set of AFR 195 heads or something similar. I was probably ripped off a little but still the cost of getting this work done to the vortecs was very close to buying aluminum heads. If I had to do it all over again I would have definitely bought the AFR heads.

About the rotating assembly - I am using Speed Pro -23 cc dish pistons, 6" Scat 4340 forged I-beam rods, Scat cast steel crank. Zero decked block with a .041" compressed thickness Fel-pro head gasket (I believe its part # 1003). The compression ratio is just over 9.0:1 If you want I can post all of the part #s for you. I intend to do it anyways when I am finished with my build.

Good luck

 

[greg82255]

Re: 383 piston cc and compression

Yea, I'd say that is pretty good. If it was gps, then rpms maybe reading a little low (ie the slip number was very low).

Anyway, sounds like you are building a boat to beat Greg. trying to double your current hp?

With all that induction breathing potential, I assume you will be running up in the 5500rpm area, and looking for a much better exhaust.

Hey hey now - My goal is just about the same. I'm hoping to get 65 out of my 383 (Ideally 70 but let's be realistic..). It looks like we'll be using the same heads, and we have the same cam.

 

[Yukonmuscle]

Re: 383 piston cc and compression

Thanks Greg! I'd love to see the part numbers for what you used. Yeah I'm leaning toward an aluminum head setup myself. Just seems like there is a fair amount of work to be done to the stock vortec heads to make them a performance head that will last. Also the resale value on an aluminum headed small block is alot better then a modified cast iron one. And if I ever sell the boat, I'll prob just put the factory 5L back in as most people would prob prefer it to a built engine they know nothing about.

And yeah I'm shooting for 65 but omg wouldn't touching 70 be awesome!!
Thanks for the ongoing help and advise

 

[greg82255]

Re: 383 piston cc and compression

Here are the part #s that I have from my invoice:

SCT-9-350-3750-5700L Scat Cast Steel 9000 Series Crank
SCT-3-ICR5700 - Forged 4340 I-beam rods
FM-H890CP-30 - Speed Pro 4.030 Hypereutectic pistons
EPG-43M-139-30 - Hastings 4.030 Rings
COM-12-417-8 - Retro-fit Hydraulic Roller Cam (same as yours)
FLP-1003 Fel-pro .041" thickness 4.166" bore head gaskets

I also used the standard Comp Cams 2100 timing set and Comp Cams 208 Thrust button/timing cover

 

[greg82255]

Re: 383 piston cc and compression

After thinking about it and realizing how much my project has really spiraled out of control, I'd have to say my biggest regret is not going with the forged pistons. It was something like $300 more. Considering about 4500 or so has gone into this engine, I think that 300 bucks for forged pistons would have been a good insurance policy. I'd get them if I were you.

 

[John_S]

Re: 383 piston cc and compression

Hey hey now - My goal is just about the same. I'm hoping to get 65 out of my 383 (Ideally 70 but let's be realistic..). It looks like we'll be using the same heads, and we have the same cam.

It looks like he is looking for some alum heads that have the larger valves and larger intake passages, and hence my comment. He also has a slightly smaller and lighter boat.

You both will have more power than you know what to do with, and top speed will be mostly a factor of your hulls.


Yukon, if you have thunderbolt V ignition, I don't think there is a way to defeat the rev limiter. May need a new ignition.

 

[Yukonmuscle]

Re: 383 piston cc and compression

John, I have no idea what ignition I have. I posted my engine serial number in another thread asking about my ignition and never got a definitive answer on what it was..... Still hoping someone can help me out

Serial # 1a605227

 

[John_S]

Re: 383 piston cc and compression

I am not up to date on such recent mercruisers. I think through the 2000's the carbed model small blocks, still had T5. I don't have a way to look up such a recent serial number and say for sure. If you took a pic of the distributer with ICM, I could tell you if it is T5.

 

[Yukonmuscle]

Re: 383 piston cc and compression

I will do that as soon as I can. Thanks

 

[Yukonmuscle]

Re: 383 piston cc and compression

Here are some pictures of my ignition if someone can help identify it

 

[John_S]

Re: 383 piston cc and compression

Looks like a T5 ICM to me.