Pistons

View previous topic View next topic Go down

Pistons

Post  4117kev on September 14th 2012, 11:23 pm

Hi Guys

I am a new 460 owner and am looking for a set of pistons that will give a compression ratio of 8:1 to 8.5:1

Bore 4.40
Stroke 4.5
Rod 6.8
heads 74cc Dove c
zero deck height

Is there a set of pistons off the shelve I can buy or will I need to order a custom set.

Thanks

Kev

4117kev

Posts: 15
Join date: 2012-06-19

View user profile

Back to top Go down

Re: Pistons

Post  dfree383 on September 14th 2012, 11:53 pm

To get that low your probably going to need a custom piston, most of the shelf stuff is only about -30cc and will have you in the 10:1 range.

Check Probe and Diamond and see what they have Listed.

Edit : Looking around a little.

Your going to need a 60cc dish, not very pratical and maybe impossible to maintain structural integrity with your 6.800 rods and stroke.

You need to look at using some D3 heads with substantialy larger chambers and use a 45cc custom dish. and maybe think about using a 6.700 rod to give the piston manufacture some room to work with.

Is this for a turbo application?

dfree383
BBF CONTRIBUTOR
BBF CONTRIBUTOR

Posts: 10912
Join date: 2009-07-09
Location: Everywhere

View user profile

Back to top Go down

Re: Pistons

Post  4117kev on September 15th 2012, 5:06 am

Yep, i am building a it with a gt55 turbo running on methanol, is it possible to run the 6.605 rod instead of the 6.8.
i figure this would give me more piston choice

4117kev

Posts: 15
Join date: 2012-06-19

View user profile

Back to top Go down

Re: Pistons

Post  dfree383 on September 15th 2012, 5:21 am

its a custom piston no matter what rod you try to use.

If your crank is a Ford Racing Ford Journal Crank, you can use a Ford 6.605 rod, typical most other aftermarket cranks a Big Block Chevy rod Journals. with a typical choice of 6.7 or 6.8 along with other others. but watch with the shorter stuff they will not clear the throws on the crank.

You need to watch wrist pin sizes too, BBC stuff is .990 and BBF stuff is 1.040.

You'd be best using some D3 heads and a 6.7 rod IMO, its a awful big dish to get the compression down with the DOVE heads.

You also need to do some more reasearch with running methanol, it will tolerate higher compression than 8.0-8.5 in forced induction applications.

dfree383
BBF CONTRIBUTOR
BBF CONTRIBUTOR

Posts: 10912
Join date: 2009-07-09
Location: Everywhere

View user profile

Back to top Go down

Re: Pistons

Post  res0rli9 on September 15th 2012, 5:38 am

You can also use a .0120 head gsk.

res0rli9
BBF CONTRIBUTOR
BBF CONTRIBUTOR

Posts: 2856
Join date: 2008-12-02
Age: 64
Location: sarasota FL.

View user profile

Back to top Go down

Re: Pistons

Post  4117kev on September 15th 2012, 8:21 am

What is the thickest head gasket you can get and would use on a turbo motor without going to copper or is copper my best choice.

4117kev

Posts: 15
Join date: 2012-06-19

View user profile

Back to top Go down

Re: Pistons

Post  quick 52 on September 15th 2012, 8:38 am

if your building new and dont have a crank,rods or pistons. maybe a smaller ci. engine will do the job you can get alot of hp when put pressure to it ive seen some small ci. make 1000hp easy how much power are u looking for

quick 52

Posts: 550
Join date: 2011-01-14
Age: 63
Location: leonard mi.

View user profile

Back to top Go down

Re: Pistons

Post  4117kev on September 15th 2012, 8:55 am

As much as I can pump out of a GT55 turbo on methanol.

If I use a 6.7 rod with a 1.245 pin height piston this would bring the piston down the bore 100thou, can this be done?

4117kev

Posts: 15
Join date: 2012-06-19

View user profile

Back to top Go down

Re: Pistons

Post  dfree383 on September 15th 2012, 9:21 am

4117kev wrote:As much as I can pump out of a GT55 turbo on methanol.

If I use a 6.7 rod with a 1.245 pin height piston this would bring the piston down the bore 100thou, can this be done?

Not the best way of going about it.

You have to look al the specific piston to make sure it will clear the crank counterweights, It be a hit and miss thing.

dfree383
BBF CONTRIBUTOR
BBF CONTRIBUTOR

Posts: 10912
Join date: 2009-07-09
Location: Everywhere

View user profile

Back to top Go down

Re: Pistons

Post  Paul Kane on September 15th 2012, 10:21 am

4117kev wrote:As much as I can pump out of a GT55 turbo on methanol.

If I use a 6.7 rod with a 1.245 pin height piston this would bring the piston down the bore 100thou, can this be done?
Yes, this is the most practical way to set up a low compression methanol burning engine. A lot of force-fed methanol drag racing engines (and nitro burning engnies) are built this way specifically and for the same reason you are asking (compession ratio). Quench is not critical in a methanol burning engine and much less so in a blown (turbulent A/F mixture) methanol burning engine.

That being said, MeOH can handle more compression ratio than 8.5:1 but there's not necessarily anything wrong with that compression ratio. Frankly, for structural integrity I'd step away from the 4.50 stroke crankshaft and go with a forged 4.30....but if you must stick with a forged 4.50 then turocharged on alcohol is your best bet.

Diamond makes 32cc-36cc dished pistons that would meet your compression ratio needs when run at .100" in the hole. 0.040" overbore is not a common bore size but rings are out there so if you can use that bore then you will be maintaining better cylinder wall thickness than gong to 0.060"overbore.

Paul

Paul Kane

Posts: 564
Join date: 2009-09-14
Location: San Francisco Bay Area

View user profile http://www.highflowdynamics.com

Back to top Go down

Re: Pistons

Post  rmcomprandy on September 15th 2012, 11:31 am

4117kev wrote:Yep, i am building a it with a gt55 turbo running on methanol, is it possible to run the 6.605 rod instead of the 6.8.
i figure this would give me more piston choice

X2

With forced induction and high octane fuel such as alcohol ... simply use a 6.700" rod instead of the 6.800" rod and run the piston .100" down the hole.

rmcomprandy

Posts: 3212
Join date: 2008-12-02
Location: Roseville, Michigan

View user profile http://www.rmcompetition.com

Back to top Go down

Re: Pistons

Post  4117kev on September 15th 2012, 6:52 pm

Thanks Guys

We already had the motor and have been running it in N/a form for the past few years and it was showing 800rwhp at the track, not bad for an old cast iron headed truck motor.

So the plan is we already have the new 4.5 crank sitting to replace the current cast item and now some new rods & pistons and we will see what it does with the turbo attached to the front of it.

Being new to 460's myself I am sure this won't be the last time I come here for advice.

Thanks

Kev

4117kev

Posts: 15
Join date: 2012-06-19

View user profile

Back to top Go down

Re: Pistons

Post  DanH on September 16th 2012, 1:55 pm

4117kev wrote:Thanks Guys

We already had the motor and have been running it in N/a form for the past few years and it was showing 800rwhp at the track, not bad for an old cast iron headed truck motor.

So the plan is we already have the new 4.5 crank sitting to replace the current cast item and now some new rods & pistons and we will see what it does with the turbo attached to the front of it.

Being new to 460's myself I am sure this won't be the last time I come here for advice.

Thanks

Kev

new and the past few years and 800 rwhp . OK

DanH

Posts: 963
Join date: 2009-08-06

View user profile

Back to top Go down

Re: Pistons

Post  IDT-572 on September 16th 2012, 2:21 pm

800 RWHP with Dove c's N/A..................... I'm impressed good job............. Shocked Cool

You may want to look at the cheap Pro Comp aluminum heads for what your doing. May fill the bill if your doing it on a tight budget.

IDT-572
BBF CONTRIBUTOR
BBF CONTRIBUTOR

Posts: 3919
Join date: 2008-12-02
Age: 53
Location: Shelbyville Tn.

View user profile

Back to top Go down

View previous topic View next topic Back to top


Permissions in this forum:
You cannot reply to topics in this forum