WHAT PISTON ??

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Re: WHAT PISTON ??

Post  gryphon68 on October 30th 2009, 2:07 pm

What kind of Piston Dish (cc's) are people running with 4.3 and 4.5 stroke and 6.700 rods?

Compression Height would be 1.345 on a 4.500 stroke, and 1.445 on the 4.300 stroke, correct?

Keeping the compression down is not the simplest thing on these big engines.

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Re: WHAT PISTON ??

Post  Northwest outlaw on October 30th 2009, 3:15 pm

what kind of hp are you looking at making?
street?
strip?
what heads are you running?
need a little more info on what you have and what you want to do?
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Re: WHAT PISTON ??

Post  gryphon68 on October 30th 2009, 3:31 pm

Just planning out a new combination for the Drag Radial car. Strictly a paper exercise right now.

The discussion is really about compression ratio and the piston dish required to achieve it. The power will come with the boost/airflow.

Most likely A460 18-Bolt Heads, 83cc chambers if I recall correctly.
Not many other head choices that help in this area, C-Heads and SCJ heads both have smaller chambers.

Was thinking 4.500 crank (no replacement for displacement, especially with 20 psi over the top), but I think its going to be simpler to go with 4.300 stroke and 6.700 rods

Talked to a guy at Diamond, they would only recommend a 50cc max dish in a 1.345 C.H. piston (4.600 bore), makes thinks pretty tight to get 9.0:1, let alone 8.5:1

Of course there is always the option of just running the damn thing on methanol and up the C.R to around 10.5 or 11:1

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Re: WHAT PISTON ??

Post  Northwest outlaw on October 30th 2009, 4:01 pm

well you dont have to meth wiyth 10.-11.cr a good c16 or q16 fuel will work with a intercooler just have to be good on the turn 2000hp is a walk in the park with turbos. my set up should be 1000-1200 on a stock block and D3 head in a 2200lbs car.
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Re: WHAT PISTON ??

Post  gryphon68 on October 30th 2009, 5:42 pm

I agree that it's not impossible to run boost with high-ish compression as long as there is good fuel in the tank.

But it does significantly shrink the safe tuning window, especially for the max effort required in D/R.

Even Lynch runs somewhere around 9.0:1 C/R. (or did . . . not sure about the new 670ci engine)

Your car sounds like it is going to be crazy if it's that light. Is it a door car or open wheel??

I guess the other question I should ask is how much meat are people able to carve out of the combustion chamber without compromising the function?

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Re: WHAT PISTON ??

Post  studly on October 30th 2009, 6:05 pm

how about the 18 bolt Thor Heads i have been hearing alot of good things about them, Northwest do you have a working turbo set up for a BBF is it Fuel Injection or blow threw. I have been looking at turbos but it seems to hard to get everthing to work right. What Ignition do you run?
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Re: WHAT PISTON ??

Post  96Mustang460cid on October 30th 2009, 9:01 pm

Here are the specs for my pistons:

4.5" bore
4.3" stroke
6.7" rod
83cc chambers (18 bolt A-460)
4.62" head gasket bore
0.030" head gasket thickness
1.34" compression height
23cc dish
0.130" below deck (w/ 10.32" deck height)

Compression Ratio = 8.57

A 4.15" stroke and 6.8" rod gets you 8.0:1 CR.



Increasing compression ratio > increasing boost w/ lower CR. Either way, you're getting cylinder pressure, but the increased CR makes for a more efficient engine.

Also, if you're going to kill the quench between the piston and cylinder head, drop it at least 0.100" down in the bore. I believe the 0.040" to 0.100" zone is 'bad news'.

Have a good day!
Michael
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Re: WHAT PISTON ??

Post  gryphon68 on October 31st 2009, 10:07 am

studly wrote:how about the 18 bolt Thor Heads i have been hearing alot of good things about them, Northwest do you have a working turbo set up for a BBF is it Fuel Injection or blow threw. I have been looking at turbos but it seems to hard to get everthing to work right. What Ignition do you run?

Definitely some bad ass heads, up to 580cfm in the Intake side. Truthfully, they are probably overkill on a turbo engine unless you building something over 650" and trying to make 3500+hp


96Mustang460cid wrote:Here are the specs for my pistons:

0.130" below deck (w/ 10.32" deck height)
Also, if you're going to kill the quench between the piston and cylinder head, drop it at least 0.100" down in the bore. I believe the 0.040" to 0.100" zone is 'bad news'.

Was hoping to keep the quench area. I agree with you though, if you are going to loose the quench you don't want to create dead/stagnate areas.

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Re: WHAT PISTON ??

Post  chappy89 on November 1st 2009, 6:03 pm

I am running Diamond pistons in my 598, twin GT47-88 engine. I can give you an idea of what to run, but really you would have to consider the whole combo. My motor makes around 9.8:1 compression with a 62cc copper gasket. I have a 6.700 BME rod, and the piston is .100" in the hole, with a 92cc chamber on the head. I have HUGE piston pins. My piston is a true flat top.

This car is designed to run Outlaw Drag Radial. Also we run VP Q16.

Chappy

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Re: WHAT PISTON ??

Post  gryphon68 on November 1st 2009, 8:47 pm

chappy89 wrote:with a 92cc chamber on the head. I have HUGE piston pins.

What heads are these?

Are the pins bigger than .990"? What size? Who recommended that?

My combo may end you being very similar to yours.
Thanks,

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Re: WHAT PISTON ??

Post  chappy89 on November 1st 2009, 9:25 pm

Talking about thickness. .300" thick H-13 tool steel. 1.032" diameter.

TFS A460 18bolt design. Custom port by TEA. If you want the baddest of the bad and want to build it yourself, talk to Don Bailey. Tell him Chappy sent you.

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Re: WHAT PISTON ??

Post  EVE on November 2nd 2009, 3:44 am

I run 10.8 to 1 on my E85 powered 502". Works great and keeps the engine more responsive when off boost. I have custom Diamond pistons that are a dish but is the whole top. The coatings are woth every penny. Hope that helps.

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Re: WHAT PISTON ??

Post  gryphon68 on November 2nd 2009, 8:48 am

EVE wrote:I run 10.8 to 1 on my E85 powered 502". Works great and keeps the engine more responsive when off boost. I have custom Diamond pistons that are a dish but is the whole top. The coatings are woth every penny. Hope that helps.

How much boost are your running? Are you using an intercooler?

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Re: WHAT PISTON ??

Post  Northwest outlaw on November 2nd 2009, 10:34 am

he is not running a intercooler and fuel he is running e85 last time i looked.
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Re: WHAT PISTON ??

Post  96Mustang460cid on November 9th 2009, 11:20 pm

I read this tonight and thought it might provide some insight to this thread:

http://www.theturboforums.com/smf/index.php?topic=133644.0

Have a good day!
Michael
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