Guys i don't understand the whole A/R thing with turbos so can someone tell me what i need for my 5K.

Hey dude try www.turbofast.com.au it has a calculator.

Hey dude try www.turbofast.com.au it has a calculator.

 

 

Cheers

garret GT25 0.63 A/R...... :dance:

garret GT25 0.63 A/R...... :dance:

 

 

Ok cool what does the 0.63A/R mean

A t25 off a silvia is pretty much the same as a gt25, they have .63 housing, and you would get one for about $100. The main difference with the gt series is ball bearing, so i guess it depends on your budget.

i got dibs on the twin carbs....HAHA

i got dibs on the twin carbs....HAHA

 

Geez youre on the ball.

 

LAst set sold for over $550 on ebay

PM me when you wanna sell em!!

haha, yeah us tassie boys are on the ball, buying parts off you before they even come out of your car!!! :dance:

 

to explain the A/R simply....its basically the compression ratio of the turbo. the higher that number the higher the boost will be for the same amount of rotations of then compressor wheel.

think of it like changing the pitch of a prop on a race boat> more water/(air) flow for the same rpm! :abuse:

haha, yeah us tassie boys are on the ball, buying parts off you before they even come out of your car!!! :dance:

 

to explain the A/R simply....its basically the compression ratio of the turbo. the higher that number the higher the boost will be for the same amount of rotations of then compressor wheel.

think of it like changing the pitch of a prop on a race boat> more water/(air) flow for the same rpm! ;)

 

 

Youre a good lad,my injection is here :abuse: ,so I'm gonna bang the thing back together with two head gaskets for now to lower the comp for the semi flat top pistons till i can get the 3K head.Just so i can setup the injection and wolf etc and move it so i can drive my GT. :lolcry:

 

Then when i get the head i will pull it again and set it up properly and then hang the turbo.

lowering the compression for the turbo can be done in more than 1 way rather than just lowering the compression ratio!!!

 

my 4k has a standard head and compression ratio, and rather than changing that I have locked the dizzy off on about 20 degrees befor. this way when you load her up/high rpm the delayed spark degreases the compression at the TIME OF FIRING with the standard C/R!!

 

so are you going to run the 3k head for the turbo set up!? isn't that just going to give you a higher C/R than that of the standard 5k!? :dance:

 

what dizzy are you currently using? electronic?

lowering the compression for the turbo can be done in more than 1 way rather than just lowering the compression ratio!!!

 

my 4k has a standard head and compression ratio, and rather than changing that I have locked the dizzy off on about 20 degrees befor. this way when you load her up/high rpm the delayed spark degreases the compression at the TIME OF FIRING with the standard C/R!!

 

so are you going to run the 3k head for the turbo set up!? isn't that just going to give you a higher C/R than that of the standard 5k!? :dance:

 

what dizzy are you currently using? electronic?

 

 

Yeah standard 5K eleccy dissy using just the mag pickup with ignitor removed amd crane HI-6 ignition controler etc.

 

If i use the 3K head with the bigger combustion chamber than the 5K it will drop the C/R not raise it right.

If i use the 3K head with the bigger combustion chamber than the 5K it will drop the C/R not raise it right.

 

Yep...but just watch how far it drops it. I think Xany used a 3K bigport head and shaved the living crap out of it and still ended up with quite a low compression ratio.

ok :hmm: ,....... so is there something I'm missing with a 5k block/3k head compared to a 4k block/3k head!???

 

I just thought it would be the same as putting a 3k head on a 4k to raise the compression!! do the 5k's have a very small combustion chamber or something?? and therfore run quiet high compression!??

 

I was under the impression that if I got a 5k head for my 4k that this would lower the C/R on my 4k, but if the above is true then this would actually raise the C/R correct??