C mod class

[form-e one]

can tell ya since modifying george luces boat i kick under 4.7 degg to keep on water....

[blueskyracer]

Chenney, post some pics of your props, your 100MPH ones too. hehehehehe.

My props are so ugly they break the camera when a pic is attempted....

Thats why I post pictures of new ones. They never look the same after being used

[blueskyracer]

Since you won't show your props here is a couple more

[pro350hydro]

Okay, okay just for you Dave M

Here is a picture of the prop Cheyney set the Kilo record with @ 104mph

Enjoy!

p.s. His name is Cheyney, and pronounced like shay knee. Not cheney, chancey, chenney, etc etc

[Kevin Martin]

ahhh come on......

we've all called him lots of different things over the years ,haha

great shot!!!!!!!

[pro350hydro]

we've all called him lots of different things over the years ,haha

great shot!!!!!!!

Oh I totally agree, and he answers to most of them. Was just trying to clarify if for those who don't know. I think his name is the only one that gets spelled differently all the time...LOL

[form-e one]

here ya go dave just for you,,,hehe,, deff getting use to the different altitude here so deff diff props,,, plus i dont run the good prop much as it very very hard on the bass gears,,,working on the 4 blade,,, that and gonna try the bounce pipes see if they even close to wanting to work,,, andthe r&d motor that i changed the intake ports on will be tested also at montana or this weekend,,, me always testing something when i race except for record races of course...

[blueskyracer]

here ya go dave just for you,,,hehe,, deff getting use to the different altitude here so deff diff props,,, plus i dont run the good prop much as it very very hard on the bass gears,,,working on the 4 blade,,, that and gonna try the bounce pipes see if they even close to wanting to work,,, andthe r&d motor that i changed the intake ports on will be tested also at montana or this weekend,,, me always testing something when i race except for record races of course...

Must of been terrible having to drink all the Crown Royal for prop bags.

[Dave M]

Nice !

Shay knee,

Looks like the props to have. Good luck on the new engine.

[blueskyracer]

Looks like C Mod is going to have a good showing in Oroville this year. Maybe I will get mine going this weekend.

[bh/]

I have been wondering about these 80mph Yamato Cmods, not that they do not exist, but I'm Irish and believe in a lot of odd things.
So I was thinking that maybe these [102s] were the ones I hear that show 130psi+, roping by hand.
If one put enough cc's of hypoid 90 in there maybe,
but with just an oily gas mix????

The stock, and legal CR is 8.6:1.
The max pressure would then be;
(8.6x14.7)-(14.7)= 112psi(gauge)
This is the theoretical max under ideal conditions.
So, is anything over 90psi not good?

[mercguy]

I have been wondering about these 80mph Yamato Cmods, not that they do not exist, but I'm Irish and believe in a lot of odd things.
So I was thinking that maybe these [102s] were the ones I hear that show 130psi+, roping by hand.
If one put enough cc's of hypoid 90 in there maybe,
but with just an oily gas mix????

The stock, and legal CR is 8.6:1.
The max pressure would then be;
(8.6x14.7)-(14.7)= 112psi(gauge)
This is the theoretical max under ideal conditions.
So, is anything over 90psi not good?

stock motors pull about 120..........mill the head, etc it WILL get close to 130

[ZUL8TR]

102 compression?

I have been wondering about these 80mph Yamato Cmods, not that they do not exist, but I'm Irish and believe in a lot of odd things.
So I was thinking that maybe these [102s] were the ones I hear that show 130psi+, roping by hand.
If one put enough cc's of hypoid 90 in there maybe,
but with just an oily gas mix????

The stock, and legal CR is 8.6:1.
The max pressure would then be;
(8.6x14.7)-(14.7)= 112psi(gauge)
This is the theoretical max under ideal conditions.
So, is anything over 90psi not good?

Your calculation assumes no temp change (isothermal) of the compressed gas which will not happen even being roped. From general gas law more accurate would be:

Compression pressure(gage psi) = CR x (T2/T1) x 14.7 - 14.7

CR = compression ratio
T2/T1 = temperature change ratio

For a reasonable 10% increase in roping temperature change the compression pressure would be

8.6 x 1.1 x 14.7 -14.7 = 124 psi gage

So 120 psi stock by rope is realistic for an engine in good shape.

[bill boyes]

Funny thing. I have owned several 102's and 302's and they all were around 120 psi never below. I would ask others what they should be and most would say 128 -130. There for a while I thought something was wrong with my motors. Until I asked Bob Goller and he said 120psi was good.

[pro350hydro]

The age old compression dispute. I've seen guys claim they got 200psi, and guys complaining about low compression (but their motors run up front). Usually these guys were using a 10$ gauge that gets beat around in their tool boxes, and/or doesn't seal properly when installed.

Do yourself a favor. Always use a screw in type gauge (that seals good), and a good quality one at that. Remember you get what you pay for.

I've had my Snap-On gauge for 15+ years, and it always produces accurate results.