hi, does the club prefer one site for comp ratio calculators over another? any one calculator site that is preferred? i used one site for my .030 0ver, 225 , flat top pistons -.070 in the hole,4.125 stroke , .040 fel-pro gasket, 40 cc big valve head and came up with 10.5 -1. another site showed totally different #'s. i will be using sunoco 110 and was trying for 11-1. should i use a .020 gasket{i have 2 nos ones} trying to make a 225hyper-pak. should the block be decked more for quench and compression? thanks, ron

I use a pocket calculator, pencel and paper.
DD

hi, i used ford muscle.com and wiseco.com for some interesting numbers. i need more block decking. ron

Do a compresion test and see what the number is and I can tell you about what the compression ratio is about. Thanks Ron Parker

Here is a site with a lot of info.
The calculator section is half way down the page.

http://users.erols.com/srweiss/index.html#tmain

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Slant Cecil

Assuming a head gasket bore size of 3.60, you have 11.90 according to this calculator.

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Slant Cecil

ron, engine is apart and freshly machined and ready to be assembled. i can't check compression psi yet. i'm just measuring and ccing everything to see if i need more machining, like block deck for more quench. ronnie

Won't the cam influence the psi numbers? I know a high overlap cam can make starting easier and give good high rpm power in a high compression motor.

Given that the /6 is not a high rev motor, are you saying that given a stock cam and a healthy motor you know what ballpark the psi would be in based on /6 experience? (Im not a veteran slanter by any means)

I thought the compression test was just for deviations from cyl. to cyl. as long as all are close and in a healthy range.


just curious
radar

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madam im adam

Static compression is just the start but it is a good place to start.
Cranking compression is the next step and is more complex and harder to test.
In general, for a "street/strip" engine, you want your final combination of static compression, cam profile and cam position to get you 150 to 160 psi of cranking compression.
DD

d, is it better to get my quench lower {.040 to .060},even if it raises my compression ratio? ron

Get the clearance as close as possible for the best results.
FYI, a 12 to 1 quanch engine is not going to run well on pump gas.
See this link for more info:
http://www.kb-silvolite.com/article.php ... ad&A_id=35
DD

i did read the kb site. the search forum shows the hpak 225 was advertised with 11.5-1 . did the dealers install a piston kit like the 170's had, or was machining also involved ? what were the engine specs for the 225 hpak{quench height + head cc's} and how did the dealers prevent detonation and other associated problems with almost 12-1 ? ron

The Hyper-Pak kit cam with high compression pistons.

Back in the days of the Hyper-Pak, you could buy 108 octane leaded fuel right out of the gas pump.
DD

Just a note about piston material. If your combination including octane is right at the limit with forged pistons, it will have detonation with Hyperutectic pistons. The alloy does not transfer the heat away as much and the pistons stay hotter. It probably helps mileage on lower compression engines and they really wear well but this is something to consider aside from strength. It is not so much of a difference that it cannot be tuned out, but it will cost you a little power to do so. If it is a racer and you want all the power you can get it might be best to go with forgings. It is along the same line as getting more power with an aluminum head or reverse cooling because you can run more compression .

i forget that some of us live in states without access to leaded racing fuel at the corner station. our local sunoco stations here have leaded 110 octane fuel that's always available, which i run in my cars. if i decide to stop using sunoco 110 ,i can just install a stock 58-60cc head and drop compression to 9.25-1 and run pump gas. does anyone know what the piston specs for the hpak 225 were ? cast? dome? compression height? ron