Deck height?

calais1965

Member
Joined
Mar 10, 2009
Hello!

I have 109 block with je pistons, GN1 aluminium heads+ cometic MLS multilayer head gaskets.

What is minimium recommended piston deck height?
What is minimium recommended piston to head clearence?

>THANKS!
JP
 
What do you want for compression ratio? You need to measure the actual piston deck clearance using a depth mike, measure your combustion chambers and make your calculations with the pistons and gaskets you have now before you decide what to do with deck height..
 
I AGREE WITH TURBODAVE231........AS FAR AS PISTON TO DECK I WOULD SHOOT FOR ZERO -/+ CLEARANCE, THEN YOUR PISTON TO VALVE CLEARANCE WILL DETERMINE YOUR GASKET THICKNESS, HOWEVER I WOULD TRY TO KEEP YOUR QUENCH DOWN. I WOULD TRY TO STAY AWAY FROM ANYTHING MUCH BIGGER THAN A .045 HEAD GASKET. AGAIN THIS ALL CONSIDERING YOU WILL RUN A DISHED PISTON. ALSO DEPENDS YOUR DESIRED COMPRESSION RATIO.
 
What is minimium recommended piston to head clearence?

Most of the information I have found says .040 minimum piston to head clearance with steel rods.
 
With a zero deck, (meaning piston at top dead center is even with deck) and a standard thickness .043 head gasket your clearance will be good. Also most turbo Pistons will have a dish so the piston to valve clearance will be more than enough .
 
Thanks for answers i think my compression rating will be 8,5:1?

This is combo what i will use:

Engine are in machine shop, body are allmost ready.
I have no idea for hp rating? But i hope these parts will take me to high nines...
109 Block + steel mains
GN1 Aluminium heads + scorpion rockers
212/212 Comp roller cam kit
CAT steel crankshaft
K1 connecting rods
Je-pistons
70 mm throttle body
Holset turbocharger (1100 cfm)
stainless steel headers
sfi balancer+flexplate

1000 cc injectors for racing fuel/ 1600cc for e85
2xaeromotive A1000 pump+ an12 lines+ controller kit
Alky control
Maftranslator pro
Scanmaster
90mm maf
type 2 ignition

Meziere waterpump+aluminium radiator
no ac, manual steering box

th200 r4 with transbrake
3500 stall non lockup
transmission shield

aluminium drums, c-clip eliminators, ta-cover, steel shafts.
Wolfes sway bar, ssm lower control arms+ strange shocks

tubular a-arms+ wilwood brakes

fiberglas hood+bumpers, jazz tank, no interior, rollgage
 
looks like you have a nice Buick.......People have gone 9s with less so you should be running about that fast, considering you have a good tune and your car hooks.
 
You will be working it hard to make 9 sec power. Not impossible though.
 
The 109 stock block is the weakest link, but like anything else I would first make sure the motor keeps detonation at a minimum. Once the Engine starts to detonate then the weakest metal/link will start to suffer in this case could be the block...Now that being said Don Cruz along with a lot of other people have gone low 9s on a stock block on a more consistent basis. However, I don’t really recommend constantly pushing the motor to go anything faster than high 9s.
 
black owned said:
where is the weak link in that combo?thanks

If I was building it with a goal to make consistent high 9 power I'd be running a little higher CR, some bowl work on the heads, custom roller cam with more intensity, and I'd need to know more info about the converter and turbo. You will be working the turbo to it's flow limit at 1100cfm. 1100cfm is 75-80lbs/min on a typical turbocharged engine. That's about what you need to have consistent high 9 power at 3500lbs
 
If I was building it with a goal to make consistent high 9 power I'd be running a little higher CR, some bowl work on the heads, custom roller cam with more intensity, and I'd need to know more info about the converter and turbo. You will be working the turbo to it's flow limit at 1100cfm. 1100cfm is 75-80lbs/min on a typical turbocharged engine. That's about what you need to have consistent high 9 power at 3500lbs

good info
 
If I was building it with a goal to make consistent high 9 power I'd be running a little higher CR, some bowl work on the heads, custom roller cam with more intensity, and I'd need to know more info about the converter and turbo. You will be working the turbo to it's flow limit at 1100cfm. 1100cfm is 75-80lbs/min on a typical turbocharged engine. That's about what you need to have consistent high 9 power at 3500lbs
If I was building it with a goal to make consistent high 9 power I'd be running a little higher CR, some bowl work on the heads, custom roller cam with more intensity, and I'd need to know more info about the converter and turbo. You will be working the turbo to it's flow limit at 1100cfm. 1100cfm is 75-80lbs/min on a typical turbocharged engine. That's about what you need to have consistent high 9 power at 3500lbs

Thanks for good info, i will try to Find flow chart for my turbo its holset hx40 super. Torque converter i havent bought yet.
Transmission is lonnies stage2 with electric transbrake.
 
compressor map.
 

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Looks like you need to build the engine to use about 85lbs/min at 3.2:1 PR to run the turbo out. So you have plenty of turbo for a stock block. I'd rethink the camshaft, CR, and probably the heads. Even running a lower than 3:1 pressure ratio I'd use quite a bit more cam. You will need peak power in the high 5000's and the converter will need to flash up near there too.
 
You're going to get close to running out of fuel pump with E85 and dual A1000's. I am going E85 with a 6776 and forged stroker 252ci motor and I figured around 160-180gph@80psi fuel consumption. Those A1000s won't put that out.
 
Looks like you need to build the engine to use about 85lbs/min at 3.2:1 PR to run the turbo out. So you have plenty of turbo for a stock block. I'd rethink the camshaft, CR, and probably the heads. Even running a lower than 3:1 pressure ratio I'd use quite a bit more cam. You will need peak power in the high 5000's and the converter will need to flash up near there too.

Thanks for answers!
What converter do you recommend for my combo?
 
You're going to get close to running out of fuel pump with E85 and dual A1000's. I am going E85 with a 6776 and forged stroker 252ci motor and I figured around 160-180gph@80psi fuel consumption. Those A1000s won't put that out.

How big injectors are you using?
 
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