Re: Compression

From: Jamie Calder (jcalder3@cfl.rr.com)
Date: Sat Oct 10 2009 - 21:31:53 EDT


--------------------------------------------------
From: "Ray Block" <BPracing@wowway.com>
Sent: Saturday, October 10, 2009 12:26 AM
To: <dakota-truck@dakota-truck.net>
Subject: RE: DML: Compression

>
>
>> -----Original Message-----
>> From: Jamie Calder
>>
>> Well the good news is that it's just a short block on an engine stand. I
>> contacted Ross and they said if it's not on the top, then look on the
>> bottom
>> of the piston below the pin (just like you (Jon) suggested). I assume
> this will
>> be the inner wall and not outer wall (I hope)?
>
> I certainly would hope it would be inner wall as I don't think it would be
> smart to stamp something on the outer wall of a piston. ?
>
>> On a similar note, what are some recommendations for a advertised
>> compression ratio for a 408 with R/T heads? What would the suggested
>> true
>> ratio be? I know the cc's of the R/T heads will be a determining factor
>> (I'm just trying to sound like
>> I know what I'm talking about now)?
>
> While I've not looked at a Ross piston catalog, the others I have looked
> at
> usually indicate their piston's compression ratio in relation to the
> head's
> combustion chamber cc's (and they usually list the most common). If you
> don't already have the R/T heads, be advised there are better choices out
> there.
>
>> I have a cam in there now but I think I'll
>> be changing it out with one from Hughes Engines.
>>
>> Thanks for any info
>> James
>
> I personally would second the vote toward Hughes Engines cams. I use
> their
> HER1418ALn (which they describe as a "mild street" cam)...lol...in my '92
> 318 Dak and I couldn't be happier. It plays just fine with my OBD-I MP
> PCM
> and I run 12.90's through a full single exhaust. Hughes' 114 LSA on
> their
> cams is what makes it work well without a flashed or standalone PCM.
> Others (Marty at KRC, etc.) may tell you a smaller LSA is better for a
> naturally aspirated engine but they all have to use a modified PCM to make
> them work. Look at any new EFI performance engine and the OEM cam is at
> least 114 LSA....for a reason. I'd ask Dave at Hughes for a
> recommendation
> and then choose maybe one size smaller cam. It will help your cylinder
> pressure and make up for any compression you may be lacking from your
> piston
> and head choice....in case that ends up giving you less than 10:1. My
> ported stock heads have been milled .022 and I run fine on 92 octane pump
> gas.
>
> Ray
> http://www.dragtruk.com/ENTRIES/20KM1FD2KWBP.html
>
>

I already have the bare R/T heads. Actually got them a few years ago from a
DML'er.
I looked for these heads in the online Mopar Performance catalog to find the
chamber cc's. All I saw listed are the aluminum heads. Are the cast iron
R/T heads still made?
I found the cc's from another source and they list the standard valve heads
and the large valve heads as 60cc's. Do this sound correct?



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