100LL Av gas ok @ 16lbs. W/head shim?????

[outlaw11j]

I am wanting to switch to av 100LL. I am running 16lbs with head shim. Will this be ok. I know several guys say it is. I just want to double check for some advice on this. Thanks

 

[powdermuncher]

So far no problem with 2 head-gaskets up to 12-16 pounds.

Cheers..........

 

[Mcx Nytro]

How thick is one headgasket compared to the shim mcx puts in the kit????

 

[outlaw11j]

Bought my sled already built. It has the Alpine front mount and have no idea how tick there shim is? Sorry

 

[Turbo Monster]

With my Alpine kit I run 15 psi on avgas.It sure seems to run alot better on avgas

 

[DARKO]

Check the thickness of your head shim before guessing is my advice.

With MCX head shim I've been running up to 18lbs for 3 years, over 9000 km's and all is well.

 

[outlaw11j]

Darko, thats the smart thing to do. I have found some other things going through the sled that needed addressing. I will also call Alpine once I make sure it has the shim installed. Thanks

 

[powdermuncher]

The MCX shim is a bit more than 3 gaskets stacked , not sure about Alpine, but it is definitely more than my 2 head gaskets , just make sure you do have a shim or find out what is done to it fore sure.

 

[DARKO]

Good man, a quick call = piece of mind, and many happy miles of saying to yourself "holy fugg this things fast". lol

Enjoy !!

 

[robertyoke]

The MCX shim is a bit more than 3 gaskets stacked , not sure about Alpine, but it is definitely more than my 2 head gaskets , just make sure you do have a shim or find out what is done to it fore sure.

the head shim is about 1 mm thick and it uses 1 head gask on each side of it.

 

[outlaw11j]

the head shim is about 1 mm thick and it uses 1 head gask on each side of it.

Looked at mine today and it is hard to tell but I think it looks like two gaskets with a metal shim the same as you have. The whole deal is about the thickness of a dime or 8-10mm total???

 

[rednytro]

you should try to find out youre final compression ratio its alot more definate than mesuring head shims and gaskets

 

[snowy1]

I measured my mcx head shim for my nytro befor instsall, the head shim is .075 plus the two stockers one on each side .095 total.

 

[outlaw11j]

Ok, I'll quit the guessing game. I take a compression on all four, factor the 16psi and come up with the final FCR. I guess thats what makes buying used without all the info makes it tough. I have been running C12 up to this point. But heading to Revy in Feb.and Cooke in March so would rather do the 100LL in my dock caddie. I have been hearing of guys having trouble getting to fill up the av gas so I am prepared with my new plastic pilots license I just had sent from the FAA to ease the tention, hopefully??
With my luck latley I'll probably just need a tank full to end up in the trees anyways.
The great thing about boost. You don't need a saw...

 

[Turbo Tim]

Avgas : I ran My Apex with the headshim at 17-19 psi no probs. over 1000 miles
My 04 trx1 with 2 headgaskets thickness at 15 psi over1800 miles
And my latest Trx1 has about 300 miles on it at 20 psi with avgas , but it has low comp pistons AND a thick headgasket .( I made 4 back to back half mile full throttle pulls at 20 psi) ......if there were gonna be any problems ,I would have found out then !

 

[Quicksilver]

boost calc

here is a link to a great boost calc on TY. If you make the changes in yellow with alt, shim thickness,low comp pistons, etc you can see your estimated octane req. and hp change too. Just click on boost calc in blue. If you make too many changes just close without saving and re-open.
http://www.ty4stroke.com/viewtopic.php?t=23214

 

[outlaw11j]

Cool calc., Thanks