Compression Ratio - Your feedback is needed

[Sascha]

Dear Forum Members,

I found a lot of helpfull information about static and dynamic compression and the influencing factors here. But Im not absolutely clear what are the maximum but secure values to strive for. The conclusion out of my reading is represented by the values listed as examples. My questions to you are:

1. Do you think this configuration will work?
2. May I ask you to share your data for reason of information exchange?

- static compression: e.g. 11.52:1
- dynamic compression: e.g. 9.25:1
- engine stability: good reliable daily street driver (vs. race)
- Max. engine oil temperatur: 225 F
- Max. cooling water temperatur: 185 F
- heat exchange capability of engine: iron (vs. alu)
- heat exchange capability of the heads: alu (vs iron)
- piston to deck clearence: 0.017 inch
- piston to head clearens: 0.044 inch
- Max. summer environmental temperature: 104 F
- min. octane rating required: e.g. premium 100 octane eurpean gas
- max. ignition retard and rpm: 34 at 3000 rpm

Thanks for your assessment and data.
sincerely
Sascha Bihler

 

[grumpyvette]

Dear Forum Members,

I found a lot of helpfull information about static and dynamic compression and the influencing factors here. But Im not absolutely clear what are the maximum but secure values to strive for. The conclusion out of my reading is represented by the values listed as examples. My questions to you are:

1. Do you think this configuration will work?
2. May I ask you to share your data for reason of information exchange?

- static compression: e.g. 11.52:1
- dynamic compression: e.g. 9.25:1
- engine stability: good reliable daily street driver (vs. race)
- Max. engine oil temperatur: 225 F
- Max. cooling water temperatur: 185 F
- heat exchange capability of engine: iron (vs. alu)
- heat exchange capability of the heads: alu (vs iron)
- piston to deck clearence: 0.017 inch
- piston to head clearens: 0.044 inch
- Max. summer environmental temperature: 104 F
- min. octane rating required: e.g. premium 100 octane eurpean gas
- max. ignition retard and rpm: 34 at 3000 rpm

Thanks for your assessment and data.
sincerely
Sascha Bihler

lets say the piston deck height averages .011 below the block deck, then you would subtract .011 from .044 and get .033, you would find a .030-.033 head gasket (.032 is very common)

lets say the piston deck height averages .011 above the block deck, then you would add .011 too .044 and get .055, you would find a .050-.052 head gasket

they measure the piston deck height after the machined block has the rotating assembly test fitted

then buy the required head gasket thickness to allow the quench to fall in that .040-.044 range

Prior proper planing , and parts selection and taking the time to do the math required well before buying and assembling components, goes a LONG LONG WAY in any engine build, at about 9.25:1 dynamic compression youll need about 105 octane race fuel , thus youll need an octane booster like toluene,UNLESS CHANGES ARE MADE TO THE COMBO, aluminum heads will make the engine less likely to detonate as they allow combustion heat to dissipate more rapidly, getting the quench distance between head and piston in the .040-.044 range tends to maximize the quench, reducing the tendency to get into detonation.
but I will point out that you have the option of retarding the cam timing a few degrees which will both reduce the dynamic compression by delaying the intake valve closing and causing the whole power band to move about 200rpm higher for each 4 degrees its retarded, you also have the option of using an alcohol/water injection system to control detonation as this significantly cools the combustion temps under load. efficient oil coolers, with electric fans and a large capacity oil pan with an effective windage tray and a baffled oil pan with 7-9 quart capacity, can significantly reduce oil temps this will also tend to reduce the engine operating temps as OIL does most of the initial parts cooling and heat transfer work in a properly set up engine.
selecting a cam with a tight LSA like 105-108 tends to result in some overlap and better exhaust scavenging, thus some of the intake charge follows the previous exhaust out the header, this much more effectively flushes out the old burnt exhaust gases and tends to increase power, and can at times cool the exhaust valve minimally, it can reduce detonation in some combos, but it can also waste a bit of fuel. the links below contain a great deal of useful related info

http://garage.grumpysperformance.com/index.php?threads/cooler-denser-air.8961/#post-54528

http://garage.grumpysperformance.co...e-required-octane-for-compression-ratio.2718/

http://garage.grumpysperformance.com/index.php?threads/no-computer-now-what.13973/#post-71209



http://www.wallaceracing.com/Calculators.htm

http://www.tciauto.com/tc/racing-calculators/

http://www.csgnetwork.com/automotiveconverters.html

 

[Indycars]

Sascha,

If you are building the 327, I'm having trouble seeing where you got a dynamic
CR of 9.25. What numbers did you use for your calculation???

Now if you are doing something different with a 383 that you mention in the quote
below then you may be just fine. I'm still wondering what numbers you used, can't hurt
to have another check if you don't mind.

viewtopic.php?t=9944

I called my own Camaro one year later. A basic version of 1968 with a 327cui SB and 210 GHP and no extras. My strategy is simple, do as Most as possible by my own ne stay as needed original to keep the status of my historical licensing plate for the reason of saving a hell of insurance and tax fees.
I modified meanwhile suspension, wheels, tyres, hood, additional gauges, RS lights, 2 line 2 1/2 inch exhaust and finally in 2011 the 383 stroker engine.

 

[Sascha]

Hello Grumpy, hello Indy,

thank's for your feedback.

First some Background Information to the situation i am in.

A german engine builder made an 383cui out of my original 327cui small block Camaro of 1968 only three years ago. The engine parts have been selected by the engine builder based on my non technical target description because of my missing technical knowledge at that time. The engine has now not more than 5'000 KM equivalent 3'000 miles. I used the Motul Classic oil 20W50 non-synthetic engine oil with increased ZDP value (approx. 6.000 Kg/cm²) for the first 1500 Kilometers. I changed to Motul 300 V Le Mans 20W60 synthetic oil as recommended by a Motul engineer. This oil contains no ZDP but therefore a increased Ester value which provides approx. 23.000 Kg/cm². (I believe that) The engine started to produce a quit rpm depending mechanic noise after the oil change. The noise gets even more quiet if the engine is hot. Two Independent mechanics stated recently to me, that my engine has either a faulty rod bearing or a flapping pisting. My original engine builder is not willing to provide a detailed list of the used components and facts like clearence, etc. to me. So I started to dig down in this subject with the information provided by this Forum. I am still in learning mode, and please be patient if I come with some more questions in the near future. But I am pretty sure at this time, that this damn engine builder used more or less cheap e.g. Elgin camshaf, quench of 53, no porting of intake to heads and so on or using original 40 year old material e.g. pushrods, etc. Please do not ask about the Money I (greenhorn) gave this ....

Ok but now let's looking forward. Based on no trust to local Shops, I am working on several options to gor for e.g. repair, repair + modification or new engine. This requires an re-engineering of my 383 small block and a design for a new engine to identify potential costs associated with. I will provide details if i am ready for the decision. AND GRUMPY IS RIGHT, WHEN HE WRITES THAT YOU SHOULD READ MORE IN ADVANCE BEFORE A PROJECT TO SAVE A HELL OF MONEY.

Grumpy, please apologize my stupid goal for DCR of 9.25:1. I verified my concept and discovered that i mixed up "ROZ (Research Octane Number)" and "AKI Anti-Knock Index" also known as average of RON and MON = (R+M)/2). But anyhow it was interesting to read something about octance Boosters ;-) So here is my corrected calcualtion for DCR and CR with European gas types and about 180°F.





Please feel free to comment, so that I can procees with selection of the gas type and afterwards the camshaft.

Kind regards

 

[Strictly Attitude]

solid cam will do that to tick then when heated it will quiet up take a video on the phone post on youtube provide link.

 

[grumpyvette]

perhaps I look at thing's far differently than many people simply because I don,t have any reluctance to pulling an engine down, dis-assembling it and carefully inspecting it, before careful re-assembly if I fail to find anything really wrong with it simply because at the worst case it will cost me only a complete set of gaskets, rings and bearings, and at most a weekends time!
that, time ,invested lets ME know whats really going on, vs being told something convenient by some guy late to see some gal at a local bar, just to get me off the phone, or something that potentially generates him more money that may or may not be true!
and in most cases only gaskets and bearings as rings generally if in good condition can be re-used. BUT if I had some UN-known tapping sound that I could not locate I'd be rather anxious to pull the engine down and inspect it closely rather than take a chance of running it and having something far more expensive to repair and potentially much more extensively destructive happening to the engine internally.
I guess I learned early on that many "machine shops" do SUB STANDARD SHODDY WORK that you really can,t trust thus your forced to verify the work and tolerances and measurements when you get parts back, so in the long run it pays to do as much of the work yourself as you can as your skills increase!

this book comes with a video that walks you thru the process, and yes I can easily understand your reluctance to do so if its the first time doing it but its not nearly as difficult or complicated as it may seem, and all the info you need is posted on the site! youll need a few basic tools for RE-assembly like a good piston ring compressor and torque wrench and having a dent engine stand will be VERY helpful, but its not something that has not been done hundreds of times on several sheets of thick plastic on a garage floor!
and it sure helps to find and join at least two local performance car clubs and get to know the serious members
theres always a compromise and on most engines the best oil temp range to reduce wear,emissions and get the best mileage is found when the oil temps kept in the 190F-215F range MOST OF THE TIME and it RARELY exceeds 220F[/color][/b]

http://www.zddplus.com/TechBrief13%20-% ... cosity.pdf

if your looking for a local machine shop,
in the west palm beach fla area
be damn sure you get all the details in writing
dates prices, details on what needs to be done
delivery dates and take pictures
these guys generally do decent work




first choice (use them fairly often to rebuild heads)

Engine Rebuilders-Palm Beach,
1722 Donna Rd, West Palm Beach, FL 33409

second choice (mostly for block line hone & decking)

Keener's Engine Machine Inc
2517 N Military Trl, West Palm Beach, FL 33409



third choice
these guys get decent reviews but Ive only been there once)

170 Commerce Rd, Suite 1A
Boynton Beach Florida 33426
https://www.mprracingengines.com/
http://www.themotorbookstore.com/resmchstvi.html

 

[87vette81big]

Cut the oil filter open Saccha.
Likely find bearing babbit material.
If not, look elsewhere .
Todays pump gas is terrible.
Detonation is enemy #1.