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The VIPER Garage  |  Generation-specific Viper Forums  |  RT/10 & GTS Viper Discussions  |  Project: Bullet-proof V-10
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Author Topic: Project: Bullet-proof V-10  (Read 6987 times)
RTTTTed
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Viper Nation - ezine
« Reply #45 on: October 31, 2010, 10:46:39 PM »

9-1 would be a better ratio for 10psi.  I was wondering about composition head gasket thickness.  I sent an enquirey to Dan @ Viper Specialty since he had some Multilayer Head Gaskets made.  I can't remember exactly the thickness but I think that he said there was a .060" gasket avail.?  Old MLS gaskets were about .044" and that would probably mean somewhere about .3-.4 reduction.  I'd give him a call and ask again Tim.

JonB had a stack of headgaskets about 12" high when I bought new ones for porting my heads last summer.

Ted
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1999 1200rwhp TT GTS - ART, 2001 Roe sc GTS- (4 sale), 440 Duster restomod (sold), 3x Stealth TTs, 92 Daytona IROC with T3, 580whp/1080wtq Cummins pickup.
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« Reply #46 on: November 01, 2010, 12:01:46 AM »

Yes, 9.1CR would be better. 
But a thicker head gasket is not the answer in my case.  The quench is already too much with .054.  I've been told by a few knowledgeable guys that a quench of .040 is ideal.  I'd rather my CR be a 9.4 and a reasonable quench, than have an ideal CR and a terrible quench.  With a bad quench, I might as well run 5# as my power will be hit hard with such a thick gasket in 10#.

My answer for the future will be to have the heads cc'd a little more.  Opening up the head cc to 80 will bring me down to 9.0CR.  85cc would put me at 8.6CR. 
The cc of the JM heads could use some more shaping in my opinion.  75cc doesn't seem to be a big change from stock.  Does anyone know the stock head cc?
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97GTS B&W: Roe S/C 6.5#, VEC3, custom W/M, Borla headers and catless exhaust, smooth tubes and K&Ns, JM stg3 heads, 1.7 Arrow RR, 3.55 gears, Fidanza, B&M sst, 661hp/683tq
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« Reply #47 on: November 01, 2010, 02:51:11 AM »

thats some great info
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AndyMac
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« Reply #48 on: November 01, 2010, 08:04:06 AM »


  I also believe that thicker headgaskets are not the answer for lowering compression in our cars. If we had hemispherical heads on the other hand, we'd be all set.

  Another option, which may not be possible with your pistons, and is pretty extreme, would be to have your piston dish worked. You would keep your quench, and gain some "room".

  Either way, 9.4 isn't bad at all IMO, especially with some water/meth.
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Andrew MacPherson
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« Reply #49 on: November 01, 2010, 08:31:48 AM »

Andy,  a deeper dish would have been the answer if I was having the pistons made-to-order.  But I bought them from a member who already had them and didn't know the specs.  I took a gamble, but I just had to trust what the seller told me about the build he bought them for.
I think it would be easier to cc the heads than the pistons.

On a side note, I just heard from a on another car forum that positive displacement superchargers, like the Roe, like HIGHER compression ratio. 
He is building a Focus with a Jackson(?) s/c and he went to 10.8CR.  I'm going to look into this to see where he got this idea.
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97GTS B&W: Roe S/C 6.5#, VEC3, custom W/M, Borla headers and catless exhaust, smooth tubes and K&Ns, JM stg3 heads, 1.7 Arrow RR, 3.55 gears, Fidanza, B&M sst, 661hp/683tq
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« Reply #50 on: November 01, 2010, 08:36:50 AM »

i dont know much about this but.... what is your quench ? maybe you do have some room for a thicker headgasket ?

a call into greg good might be worth it. hes always willing to help us out
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« Reply #51 on: November 01, 2010, 08:50:52 AM »

Phil,
the quench is the area/volume between the top of the piston and the deck of the cylinder head.  I still don't understand its importance fully, but some engine builders say it is the most critical aspect in regards to making power.
I've been talking to JD about my build for awhile.  He builds his engines and has really helped in choosing the parts and specs for my rebuild.  He is the first one to tell me .040 for quench is ideal.  But I heard this from others as well.

I would be interested to talk to GG about this.  I would also like to hear what he likes for head cc compared to the JM head cc.
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97GTS B&W: Roe S/C 6.5#, VEC3, custom W/M, Borla headers and catless exhaust, smooth tubes and K&Ns, JM stg3 heads, 1.7 Arrow RR, 3.55 gears, Fidanza, B&M sst, 661hp/683tq
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« Reply #52 on: November 01, 2010, 01:07:55 PM »

if you got JD on board, youre good to go. that guy helped me so much i cant even say... im pretty sure GG told me to use .040 as well.
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Viper Nation - ezine
« Reply #53 on: November 10, 2010, 08:42:27 PM »

Thought our headgaskets were about .046"?  Some thinner and some thicker?  Stock compression for the Gen 2s is 9.6 I think?

As far as quench making a really large difference, I don't think so.  Back in the "old" days we used 67HP heads on our newer 440s because they had a .5 compression increase not because of the quench area of the heads (68 & up all had combustion chambers that were nearly the entire cylinder area.  The theory then was that the gradual change from wedge area to entire cylindeer area was that the flame travel was inhibited by the drastic change in direction (90 degrees) for the flame coming out of the combustion chamber.  I think there may be a difference in cylinder filling and volumetric efficiency as well.  Since the difference between the smaller quench area and the larger quench area was considered to be nothing, I don't think that there's a whole lot of HP in that area.  I think that the difference is emissions (opinion).

I think that the difference in quench allows the compression increase.

My opinion is merely an educated one and I'm not an expert.


Ted
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1999 1200rwhp TT GTS - ART, 2001 Roe sc GTS- (4 sale), 440 Duster restomod (sold), 3x Stealth TTs, 92 Daytona IROC with T3, 580whp/1080wtq Cummins pickup.
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« Reply #54 on: November 18, 2010, 02:51:59 PM »

Yes, 9.1CR would be better.  
But a thicker head gasket is not the answer in my case.  The quench is already too much with .054.  I've been told by a few knowledgeable guys that a quench of .040 is ideal.  I'd rather my CR be a 9.4 and a reasonable quench, than have an ideal CR and a terrible quench.  With a bad quench, I might as well run 5# as my power will be hit hard with such a thick gasket in 10#.

My answer for the future will be to have the heads cc'd a little more.  Opening up the head cc to 80 will bring me down to 9.0CR.  85cc would put me at 8.6CR.  
The cc of the JM heads could use some more shaping in my opinion.  75cc doesn't seem to be a big change from stock.  Does anyone know the stock head cc?

You have got it right.  Quench is important, and you want to be around 040.  The hp difference is noticeable on a good design but the biggest reason to do it is not the power gained but the resistance to detonation!  You will get more timing into your motor on the same octane at 040 quench than you ever will at 054.  It is just safer.  A wide quench does not like low octane and high boost combined with high compression - it's a recipe for disaster.  

In your case I believe 9.4:1 at 040 quench plus water/meth will be fine.... BUT you must tune it to run the water/meth all the time when boost comes on, not just on a kill tune.  Otherwise you will have to take a lot of timing out.  On a Subaru we ran 18lb boost on 24 degrees timing on pump gas with water only (no meth added) at 9:1.

re the old 440 closed chamber heads - they were dogs and taught nothing about the advantages of quench.  There has been huge advances in head design to the point that a good wedge head today is the equal of and in most areas superior to the hemi head.  The advances are in smaller chambers but very well designed, with smaller ports for high cfm at high velocity, and pushing the flame under the exhaust side.  This is why you see engines like the LS7 get 30mpg, pass emissions, yet make over 500hp from 7 liters on a conservative tune and mild cam.

Fat gaskets are not cool, and I'd run pistons proud of the deck to get 040 if that is what it took with a 046 gasket.

Heffner did 2 sister SRT10 twin turbos back in the day when nobody had done an SRT with AEM as no-one else had figured out how yet except Jason.  They were identical setups except for the pistons and heads.  The black one (which first belonged to Krazy/Chris) had typical forged slugs used by Heffner at the time (I forget which brand he used).  That car made 840 or 860rwhp (I forget which) at 14lb boost on a C16 mix.

The silver one (belonged to a friend of mine) had pistons I provided very specific instructions to Jason to have made and engine machining/assembly instructions to match that design.  I chose CP and Jason sent my instructions off to them along with a set of heads.  That car made 950rwhp at 14lb boost on a C16 mix.  The mildly ported heads accounted for most of that gain, but comparing to later cars the best Heffner and I could come up with was that the pistons were worth around 30rwhp.  Most of that was due to the tight quench (0375") but also due to the better dish design and the coatings.  

The big difference between the tight quench car and non quench car was the off boost response.  The car with tight quench was crisper than stock even off boost, it was very responsive.

The piston design was not my invention, I'm not that smart, it came from Pro Stock technology that a good friend of mine passed on to me and we ran with it.  It worked.
« Last Edit: November 18, 2010, 02:58:29 PM by Torquemonster » Logged
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« Reply #55 on: November 20, 2010, 08:33:24 PM »

Had to close off the last post due to work. 

The piston design we used to maximize quench was to mirror the combustion chamber precisely into the piston dish so that the dish outline perfectly matched the chamber.  The depth simply determined valve clearances and final compression.  That was why we had to send the heads to CP.  The quench was .0375 and the compression was designed at 9:1.  This design offers the largest quench area possible on a wedge head, the dish ensures a useable compression ratio whereas pro stock no doubt ran a small dome into the chamber.  CP may have issued a part number for that set, I never bothered to find out.
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« Reply #56 on: November 20, 2010, 11:41:14 PM »

humbling thread

outstanding work

thanks for letting me be a fly on the wall
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