Neat calculator for those of you running boosted engines.
http://www.wallaceracing.com/boost-compression-ratio-calc.php
http://www.wallaceracing.com/boost-compression-ratio-calc.php
Boosted C/R
- Thread starter Silverback
- Start date
according to this I have 16:1...wow!..
pokeytemplar
Full Access Member
I just wish I could find a calculator that would also work with the effective compression ratio (with cam specs). You know how it goes 10:1 mechanical but 6:1 NA cause the late closing intake valve then to 12:1? from15psi of boost! I guess the biggest problem is that since it is a dynamic system all you can really calculate for is best/worst case scenarios.
pokeytemplar said:
These help?
http://www.virtualengine2000.com/DCRCalculator.htm
http://www.wallaceracing.com/dynamic-cr.php
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belgiumbarry
Full Access Member
o my god... even with my ROE stock pulley... ( 6 ? ) ... i need RACE FUEL ! 
COOL POST SILVER!Silverback said:
eddie should be around 16 or so, hehehe, no details furry one:itsme: :aetsch:
pokeytemplar
Full Access Member
Ronnie,
You deleting your posts? I get the emails saying what you posted but when I check the forum I see nothing. I don't have you on any ignore lists, is there anything else I could have checked by accident?
You deleting your posts? I get the emails saying what you posted but when I check the forum I see nothing. I don't have you on any ignore lists, is there anything else I could have checked by accident?
pokeytemplar said:
Pokey-
Yeah, I deleted one because I saw a smiley face on BelgiumBarry's last minute, so I thought he was kidding about needing race fuel....
All you missed was that (N.A.) static and dynamic compression ratios never change and are fixed by a given engine's design, or mods, and are also fixed (more or less) in a supercharged application as well. As you were alluding to in your post, WHEN the intake closes determines how much swept volume is left to squeeze and determines dynamic compression (N.A.) which is ALWAYS lower than static. In any case with either n.a. or forced induction, NO compressing takes place until the valve is closed!! The compression ratio number the program spits out may make you go "Hmmmmmmmmm", though...
Actual Cylinder Pressure is the one that changes and is the one that needs to be dealt with and tuned for; but would be near impossible to design a calculator program for because of the varying (running) engine conditions. So if an engine is pinging, for example, pull timing and/or use a fuel with more octane, becomes the practical fix, regardless of the numbers...
An inexpensive cylinder pressure monitor sure would be useful !
I always enjoy reading your posts...
Ronnie
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rottenronnie said:
Very well stated Ronnie.:congrats:
pokeytemplar
Full Access Member
Ronnie,
I agree completely with your statements. I have Dynosim and like looking at the specs of different builds. It is interesting how the VE of the engine can be well over 100% (at high rpms) in a NA build just by leaving the valves open a bit longer and letting inertia cram more air in. However, then you have the usual tradeoff at the low end since there isn't enough inertia to keep the piston from pushing air out.
I agree about the cylinder pressure monitor. Think how well you could tune based on cylinder pressure. No guessing, no listening, just pure data. I had read once that there was one build into a spark plug (BMW maybe?)
I agree completely with your statements. I have Dynosim and like looking at the specs of different builds. It is interesting how the VE of the engine can be well over 100% (at high rpms) in a NA build just by leaving the valves open a bit longer and letting inertia cram more air in. However, then you have the usual tradeoff at the low end since there isn't enough inertia to keep the piston from pushing air out.
I agree about the cylinder pressure monitor. Think how well you could tune based on cylinder pressure. No guessing, no listening, just pure data. I had read once that there was one build into a spark plug (BMW maybe?)
Thanks Silverback...
Robert- BEST of luck with your ambitious project. Sometimes when you stare into the engine bay and look at an unfinished project like yours, it is hard to visualize the final product. Hang in there !!!:rock: :rock: :rock:
Ronnie
Robert- BEST of luck with your ambitious project. Sometimes when you stare into the engine bay and look at an unfinished project like yours, it is hard to visualize the final product. Hang in there !!!:rock: :rock: :rock:
Ronnie
pokeytemplar
Full Access Member
Ronnie,
I agree with that statement completely. I just wish I knew alot more about this stuff. I guess that is the silver lining to moving slowly. Gives me PLENTY of time to research and learn things before spending the money and implementing them. I have made a few bad choices in purchases but nothing that can't be used in other projects. Wish I knew more about piston design. That is the one that has me worried. I want ones that can stand up to a beating but I don't want to waste money on features that I would never use. Currently leaning towards JE's chevy line. Price will be reasonable and should withstand everything I can AFFORD to throw at it.
I agree with that statement completely. I just wish I knew alot more about this stuff. I guess that is the silver lining to moving slowly. Gives me PLENTY of time to research and learn things before spending the money and implementing them. I have made a few bad choices in purchases but nothing that can't be used in other projects. Wish I knew more about piston design. That is the one that has me worried. I want ones that can stand up to a beating but I don't want to waste money on features that I would never use. Currently leaning towards JE's chevy line. Price will be reasonable and should withstand everything I can AFFORD to throw at it.
pokeytemplar said:
Pokey-
We are ALL continuing to learn. If not, top fuelers would still be running 7s and Pro Stocks, high 9s.
Anyway, no need to worry on pistons... The only real design problems I've encountered were those with a dome so high, they actually PREVENTED combustion across about 1/3 of the dome! I gained power with the big increase in compression to go with the big cam but lost (or maybe broke even?) to poor combustion...that was a number of years ago, but you learn from it..
The best information you will get (I think) is to talk to the people that make them, not retailers necessarily but those that actually make them. Tell them what you want to do and how much power you want to make and then listen to what they have to say. I'd keep it simple, go with full floating pins, good locks and rings and make sure the piston-to-wall is correct.
Longer rods (all else being equal) bring peak torque and peak horsepower closer together (in the r.p.m. range). I don't think your rod angle is enough that side loading is going to be a problem.
Above all:Keep detonation away and it's all good...A good quench area is important but I don't know how low a compression ratio you are going with because you are building for forced induction.
Take your time and enjoy the project. As far as learning goes- Guess who is going to be the EXPERT on YOUR finished project??? :rock: :rock: :burnout: :rock: :rock:
One of many: http://www.kb-silvolite.com/test/article.php?action=read&A_id=35
Ronnie
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pokeytemplar said:
For Pistons,I went with CP Racing custom pistons,my builder designed the piston for my ROE and NOS applicaton,lowered the compression ratio,adjusted the forge in the piston(strength in piston) ,lowered ring landings,oversized GM style wrist pins with wire locks and there's also (I forget what they are called:dontknow: ) but grooves in the top of the pistons for valve clearance.
Yellow venom said:
Valve reliefs...
That's the thing with the custom stuff, have them built the way you want 'em.
It sounds like you have a very solid build there Joe. 2010 should be a blast in Devon or better yet, Mission !!:elefant: :burnout: :elefant:
Ronnie
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rottenronnie said:Valve reliefs...
That's the thing with the custom stuff, have them built the way you want 'em.
It sounds like you have a very solid build there Joe. 2010 should be a blast in Devon or better yet, Mission !!:elefant: :burnout: :elefant:
Ronnie
Valve reliefs are what those grooves are called then?
Yeah Ron its gonna be fun for sure,you gotta come to the track here at the end of May,I have a set of M&H's on their way also,it sure sounds sweet too,I gotta get all my gauges installed yet and pull off my headers,put a couple more bungs in them ,get them coated and then finish of my tail pipe for my Bassani exhaust and run it:burnout:
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Yellow venom said:
Yup, just valve reliefs.
I don't know if I'll have my truck ready for May, but I'll get up to the track to see you run foh sho.
rottenronnie said:
And whats up your sleeve??:dontknow: PM me so were not hoeing the thread.
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