147 replies to this topic

[N/A-PWR]

Just what I thought,

One way or another we can do it

[rodomo]

Maybe 2 starfire heads could bolt on to 253 to solve the low comp issue?
The valley might get a bit busy though?

[N/A-PWR]

After looking for more dome 3.685" pistons,

 

I noticed a lot of other pistons around 93.5mm or so to use,

 

so picked these ones:-

 

http://www.summitrac...p50mm/overview/

 

and for a bit more of a skim:-

 

http://www.summitrac...lp-h1103cp-75mm

 

 

apparently, if you have a revving motor, we should add another thousandth piston to bore clearance,

 

so the top one could be alright for a 208 bore ( 3.685" ),

 

or if a bit small, we can use the bottom one, and give the bore a bit more of a skim. 

[warrenm]

Without reading all 4 pages, what rods do you intend on using?

[hip6]

Should be working for nasa....when's this rocket ship gonna be ready for take off.
Hope to see it in this lifetime....it'd wanna be worth it.

[N/A-PWR]

Hello Warren, great pick-up,

 

I was looking for a Dome top piston, of the W73 Northstar Piston that Oldjohnno has in his Holden 6 bible, and here too.

 

http://www.summitrac...w/make/cadillac

 

and realize the pin diametre is smaller 0.866 in the W73, vs the 0.946, which is quiet a bit bigger, for the Eagle 5.710" rod.

 

Search is on.

 

what rods do you intend on using?

 

 

Great point DJ,

 

I was thinking of my 0.100" shaved, 186 chambered head:-

 

 IMG_6608.jpg   62.26K   1 downloads

 

Considering you wouldn't be able to use small chamber head with those slugs at zero deck havnt you gone backwards?

 

 

Had a bit of time to look around again.

 

Hope to see it in this lifetime....it'd wanna be worth it.

 

Gave you a like button, for the hurry-up.

[N/A-PWR]

 Chamber Piston Assembly.jpg   71.2K   1 downloads

[warrenm]

Small chambered head is what you need, not large.

[N/A-PWR]

No worries Warren thank's,
 
same as what DJ said too, backwards,
 
but I am happy with this heads performance for the moment,
 
so I was just seeing what pistons were available to help out. 
 

Small chambered head is what you need, not large.

 

 

Question:-

 

How much trouble is there to close chamber a head from an open one?

Edited by NA-PWR, 18 March 2015 - 02:51 AM.

[warrenm]

No problem at all, if you have the gear to weld cast iron, machine head surface etc. 

[SA EH]

Then wouldn't the open chamber head make Dave's hopes of achieving 14:1 seemingly impossible??
Surely he would have to use the closed chamber to get anywhere near his goal.

[N/A-PWR]

Thank's for the great info fellows, 

 

I need a piston like this:-

 

http://www.chevydiy....evy-big-blocks/

 

these type of pistons have off-set pins to counteract the balancing.

 

 

If I cannot achieve the 14:1 CR/DCR, so be it.

 

 

There may well be imaginary calculations in the 80's that caused me to think all this could be done,

 

but I appreciate everyone's efforts to sort something out,

 

whether it be 12:1/13:1. 

[N/A-PWR]

oops, they did the 14:1 in the 70's, and I was told by the horses mouth in 1981. 

[N/A-PWR]

Great Man Oldjohnno. 

 

 

 

 

Like button for you.

The first thing I'd do would be to work out exactly how much CR I could run with the available fuel and cam. 

[TerrA LX]

The first thing I'd do would be to work out exactly how much CR I could run with the available fuel and cam.

This would be the first port of call.
 

[N/A-PWR]

So far into the research for CR vs Fuel use, using a 274@50 cam, at 13:1,

 

looks like we can run low octane ( 91 ) fuel for the street ( lower rev range, non power band ), and high ( 112 ) octane for the track ( WOT ). 

 

 

but as E85 is readily available at the Petrol bowser, converting the fuel system to run E85, is the all round solution.

E85 is 112 octane, and keeps the engine cooler.

[LC-GTR-1969]

Thats a very long duration cam- is that the cam you are currently running or is this the cam you are planning on using?

 

What is your motivation for running such a large duration? You could run 12:1 with less duration and end up with a similar result (just less stuffing around). I am guessing to are into it for a challenge, but at the end of the day it may not quite give you what you expect...

 

Not trying to be a dampner- I love a challenge also, and can see why you are keen to see it through...

[N/A-PWR]

Appreciate your post Justin,

 

My challenge is the RAT theme as you know, using the wildest bits and pieces that can be put together.

 

 

My idea started by recreating past events that worked, package them all, to create my last Torana build:-

 

 

- curious to see such a duration/combination run.

 

- need idle low as possible, 750rpm will sound nice.

 

- higher the compression, the Cam's powerband cuts in earlier, and E85 is more efficient.

 

- aim is 128kp/h in first gear, hoping to use 3rd gear at 60km/h, without jumping all over the place.

 

- another short motor when needed.

 

Thats a very long duration cam- and can see why you are keen to see it through...