PD/VE compression ratio dilemma

[oldskool rich]

i thort it was expensive to send a shirt to the states, i would doubt it wud be worth it. ill find out tomoz

[blkboostedtruck]

boys think big! Rich, load up up a shipping container and make it worth your while!
i see dollar signs! i can make us some money! i been doing it for a while!
Duane

[greg123]

What about squish?  It's not a petrol and there isn't a similar flame front, but if you reduce compression by  gap around the piston, you have less density and velocity in the swirl in the bowl.

Less in the bowl could mean the flame front isn't contained and touches the sides or plain doesn't mix well, either case result down on power, black smoke and soot.

Now, how much this matters, is anyone's guess.  It's all about what happens at TDC, when the piston is an inch down it won't have much effect.

But - there is a reason why pistons nearly touch the valves and cylinder heads and all the air is forced into a bowl.  The more you cut away from this, the more potential problems.

I'd stick with the stock gasket, recess the valves a little if you have to and grind out the combustion chamber a little if needed to reduce comp ration, then full ceramic coat.

IMHO, Greg.

[Tintin]

yes...please...please...this could change my project potential (for the 'rado) completely.

Joe

Humm...   Joe, the 16V PD already exist here,  in the passat.

[oldskool rich]

do you guys not have audi over there? 2.0 pd is very common in these and its the same

so hang on ur saying i should trim off the lip around the combustion chamber and then ceramic coat it?

i suppose that makes sence but how much should i take off?


my friend was telling me that ceramic coating doesnt increase strength it just helps the heat disapate

[greg123]

Correct

my friend was telling me that ceramic coating doesnt increase strength it just helps the heat disapate

[RabbitGTDguy]

yes...please...please...this could change my project potential (for the 'rado) completely.

Joe

Humm...   Joe, the 16V PD already exist here,  in the passat.

Martin,

Yes...I know. But they are SUPER expensive to buy and hard to find as there weren't that many over here.

Have a source for a nice PD at a nice price? I'd like to do PD or CR for my rado project ...

Joe

[snakemaster]

http://www.csgnetwork.com/compcalc.html have a look

[RabbitGTDguy]

Correct

my friend was telling me that ceramic coating doesnt increase strength it just helps the heat disapate

Thats exactly what it does. I never said it would increase strength...read my posting regarding why I ceramic coated and you'll find *and I believe I mentioned in here as well* that it was to prevent dissapation of heat through the piston...thus reduce lost potential energy in the form of heat. I REMOVED the bowl lip to reduce a failure prone area of the ALH pistons with high heat/boost/fuel *cracking at the bowl/lip* and effectively reduced CR WITHOUT effecting squish volume.
Doesn't strengthen...promotes efficiency through less heat energy loss *best bet would be valve faces, piston tops and pathways* and simply dissapates heat that could potentially damage your pistons.

Joe

[oldskool rich]

so i need to lose the entire lip of the combustion chamber, coat the pistons, valve faces and bores?

that sounds costly

ill see what i can do :roll:

[RabbitGTDguy]

NO

On PD pistons, there isn't much of a lip if I remember...I wouldn't worry about it there but its an EFFECTIVE way to lower compression on ALH style pistons, etc.

For the ceramic coating, you could get away with NONE, you could be fine with just the pistons...or you can do the lot..pistons, valve faces and the exhaust track. NOT the bores.

Coating its your perogative...some believe in it...some don't.

Joe

[jtanguay]

if you get the ceramic coating, make sure its done right... apparently if it doesn't adhere to the surface (from improper prep) it can flake off  :shock: but i'm sure any reputable shop thats been doing it for years and has good feedback, will take care of you.  

it's probably a really good idea to get it done, especially on a diesel.  you want all of that heat to be at the turbo!  :twisted:

[RabbitGTDguy]

Mine was done professionally and I wouldn't have it done any other way because of the prep needed.

SwainTech.... can't say enough good things and their reputation speaks for itself in MORE than one arena.

Joe

[Rub87]

I have the idea you guys are totally twisted up..

1. A 16v PD piston will not work with a 8v head.. why? Because the bowl is in the center, and with all 8v heads it has an offset towrds the injector.

2. increasing squish volume is bad, don't do it

3. 8v PD pistons have approx the same lip as 8v PD pistons, removing the lip is also not the optimal way to drop CR unlike the 16v PD pistons which are completely different

4. the pistons you can use to create a 2.0 8v tdi are: T4 2.5l pistons, 81mm without internal oil cooling passage or better 2.0 PD 8v pistons, from engine codes liks BMM etc, found in some passat, audi A4, skoda superb, altea freetrack etc

5. with the thinking you are doing now there's no way you'll get close to the fasted 8v tdi , the guys from profituning in slovakia are running high 10's with PD technoligy, 82mm forged pistons, some rods/girdle, and big gt25v + NOS

[jiggs]

wwooooowwww :shock:

pics pics pics!!! pleeaasssee :oops:

awesome... you guys rule...  2.0 16v tdi pd with alh engine... brutal

again, pics? :oops:  :oops: