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con rods

Posted: Mon Sep 04, 2006 11:14 am
by rz
as i am placing gregs supercharger(6 to 7 psi) on to my 3,0 12V engine i was wondering whether the gta rods are a better option.
i bought myself an extra sz engine, but the compression ratio is 10,5/1 standard.
maybe buy some lower compression pistons and ,when necessary,place the GTA rods.
the rods are 84 euro(109$) a piece
the extra engine is okay and has only done some 78.000km, so i don't want to waste money on mods that are not realy necessary!
i also want to use the 164 intake plenum with a chargecooler.
who can give me some advice that can make my engine reliable and powerfull without boosting the cost to astronomical figures!
THANK YOU

Posted: Tue Sep 05, 2006 5:57 am
by rz
no response??barry,jim......

Posted: Tue Sep 05, 2006 8:08 am
by Barry
Well,untill I see that SZ engine in my workshop with my name on it,I dont talk to you.. :wink: :D :D hehe..

Yes,Its a good idea to go for new gta or 164 type rods here..Are you opening your motor up?If so, replace the rods I reckon..
I also would not be shy to reprofile the exsisting piston for a lower cr..Just keep the deck thickness in mind..
New std headgaskets should be fine for 6/7 psi boost..Id use Victor Reinz though..
Let us know how it comes along,ok?
8)

Posted: Tue Sep 05, 2006 10:59 am
by Jim K
Marc, all manuals I have state SZ compression ratio as 10:1 same as the 164QV. All other 3liter engines have 9.5:1.
Jim K.

Posted: Tue Sep 05, 2006 11:25 am
by rz
he barry,
i am going to open up the engine!but the m62 is only big enough for about 7psi pressure, so taking much material off the piston will not be necessary.but i can send the pistons to you and maybe the heads....
what do you propose?

Posted: Tue Sep 05, 2006 5:50 pm
by Rookie ROX
rz wrote:he barry,
i!but the m62 is only big enough for about 7psi pressure
Where did you get that figure from? Site states it can go up to 12psi before it starts to run out of puff. However the 'normal' standard is to be running about 7-8psi through them.

I believe Greg says that the internals can take 7-8psi, but recommends putting in non-interference pistons for anything higher for lower compression, and to help prevent putting a large hole in the block.

ROCK ON
R~R

Posted: Wed Sep 06, 2006 9:59 am
by Greg Gordon
Allow me to clarify the maximum boost issue.

A long time ago I did list the maximum boost with the MP62 at around 10 and 7 psi for the 2.5 and 3.0 engines repectively. These figures were based on information I gained on the original functional prototype blowing through a large 3 inch diameter pipe.

HOWEVER, those figures have changed considerably. The new numbers are 14 and 11 psi maximums assuming near stock engine redlines. The increae in available boost is almost entirely due to a reduction in the size of the discharge pipe down to 2.5 inches. It could be even higher with a 2.25" inch pipe which is closer to idea. However
the throttle body is 3.25" and the discharge port's outlet is 3.00" so fabricating a 2.25" pipe to connect these two things would be kind of a pain.

Now the maximum that the engine can handle is another matter. I don't think I ever said what the engine is limited to. I certainly have not tested any engine to destruction. I feel safe with about 7 psi on either motor.

My daily driver GTV6 is running 10 psi on stock motor (original pistons, rods, etc.) However it has water injection which provides very very powerful anti detonation control. It provides detonation control about equal to a 25% increase in octane! The water injection system does not provide a meaningfull increase in air density. Air density NOT boost is what counts as far as making horsepower goes. For density you need an intercooler.

Anyone who want to see it or ride in this weekend at the Italian car fest in Dallas is welcome. My wife will also be driving it at Texas Motor Speedway on Sunday.

Posted: Thu Sep 07, 2006 4:35 am
by rz
the maximum of a stock engine is about 6psi,more is very dangerous and depends on coolingability of the head.
aluminiumheads are favourable.
i am surely not going to exceed the 6 psi and i am adding a chargecooler,which is not really necessary but for safety.
i have to go gotec,does anybody have some mapping for 3.0 supercharged?