Compression

[Edgefevah]

So I am curious as to how much the compression would be changed if a person had a 95tm block(deeper dish pistons) with 93(non-fast burning) heads?

 

[Edgefevah]

Well I just went out to the truck to see exactly what engine block I have and I now know 100% that it is a 95TM block with the 93TM heads. So given that the block does not have the "fast burn heads" would this not bump the compression up? given that there is an increase in space in the combustion chamber?

 

[Edgefevah]

ok, so Im going to do all the math too see where my real CR is.

Does anyone know the CC differences between the dished pistons?
The tech section says there are three different styles of dished pistons, I have the 95 style.

any help or a link or anything would be very helpful!

 

[SenorNoob]

I thought that combo had the opposite effect. Pretty sure I've read it was the newer heads on the older engine that was a problem due to higher compression.

 

[Sasquatch_Ryda]

It will lower the compression ratio.

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[Edgefevah]

The cam bearings are pretty cheap, fresh bearings for a fresh cam =)

90TM/93TM + 91-94 style pistons = 9:3:1

90TM/93TM + SOHC pistons = 10:1

95TM/98TM + 91-94 pistons = 10:1

95TM/98TM + SOHC pistons = 11:1

90TM/93TM heads + 95-98 pistons = 8:9:1 compression (need to check on that) this is your best bet if you plan on turbos or a supercharger.

All those numbers I confirmed with BIRD on RPS (Doug904's stage3 head builder)

The 410/422 cam love the 10:1 compression, although it would require 93 octane to be 'streetable,' and you couldnt run any forced induction... although nitrous loves the higher compression also

Not all head castings are the same! I recommend these guys for heads http://www.alabamacylinderhead.com/fordproduct.htm

The stock ford castings are weak around the valve seats and are more prone to cracking. The MAHLE castings are much more resistant to cracking, they are also what alabama cylinder head sells.

The MAHLE castings were what BIRD (again, doug904 ported head builder) used when he built and sold stage three heads.

if you plan on using the newer style heads, use the 98TM heads, they have a better flowing exhaust runners. Both the 95TM and 98TM have the smaller fast burn heart shaped chambers

haha, is it not a coincidence that I find this info posted by CREAGER that it would bring it down to 8.9:1??? lol. I guess in reality it ain't much lower then 9.0:1.

Now to decide whether or not I should increase the compression to 10:1 or keep it low and throw a M90 on it.

 

[AllanD]

the 1995-up 4.0 has larger piston dish to compensate for the smaller TM95 cylinder heads

This is just what you'd want if you want to put a low pressure blower on your engine
(Eaton running 4-5lbs)

The OPPOSITE combination of a 1993-94 block running 1993-94 heads would raise compression, which is what you'd be real happy with if you lived in Colorado or Wyoming

I have a set of parts for this just in case I ever move to Wyoming where my brother lives

 

[Edgefevah]

This confirms my decision on what my end goal will be with this truck, definitely going to supercharge it. port and polish then throw a 410 cam in there and ill be one happy ranger owner!!!

 

[UrbanRedneckKid]

Hey! Allan is alive! Sweet!

That's all, sorry for threadjacking.

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