19.5:1 in 1999? And Info on 1999 improvements

[AndyL]

I read here:

http://www.amghummer.com/Diesel/GM99Diesel/6_5LV8TurboDieselFeatures.htm

That the compression for 1999 was lowered to 19.5 to 1. Does this mean I could possibly safely run boost pressures to say 15 or 17 PSI?

[richard7]

As far as I know, the 19.5 CR, 215 HP engine was never produced (although it was supposed too, but GM changed his mind) for our road trucks. Like some UFOs, people are talking about it but never saw any...

20.2 CR and 195 HP/ 430 lb-ft is what should be your engine.

Increasing boost more than 12 psi is not worth much as the intake temperature goes too high and the engine computer is cutting back on fuel and boost to protect the engine from melting. If you use an intercooler, the lower CR will add some safety to the head gasket...

[More Power]

What Richard said, plus....

GM made plans to install the 6.5 in the 1999 Silverado body style trucks, but just a few months before introduction of the new models, GM changed their mind.

To prepare for the continued run of 6.5's, they cast new motor mount bosses on the driver's side of the block, uprated the cooling system with a 21" fan, installed 19.5:1 pistons, and reprogrammed the computer to produce 215 hp and 440 lb-ft of torque.

All this was very close to going into production, but the 6.5 was pulled from the engine option list just a few months before introduction of the 1999 model year Silverado's.
:(

So, all 6.5's produced and installed in new "classic style" platforms got the 1997-98 engine and programming.

I suspect the conflagration with Stanadyne played a part in that decision.

MP

[cruzer]

According to the "1999 Feature Articles" the 19.5:1 pistons were used in 1999. I think somewhere around 1999 or maybe 2000 the block was the new alloy used in the Hummer. Kennedy or Pennisular would know.

On my mechanical inj 92 I run max boost around
14 psi. If I set it at max 12psi, there is a diff. I loose speed/rpm pulling hills. At 14psi speed stays constant w/minimal loss. Maybe 1-2mph.
Stk pistons, Eng temp no more than 205* on a 90* day ,EGT after turbo 950*. It is intercooled. FYI

[cruzer]

I stand corrected. I guess you cant believe everything you read.

[richard7]

The GEP 6.5 grey iron/molybdenum block was produced starting november 2001. Even my 2001 van doesn't have the "Moly" block. :(

With an intercooler, there is naturally no problem going over 12 psi boost... ;)

[AndyL]

So, all 6.5's produced and installed in new "classic style" platforms got the 1997-98 engine and programming.
Does this mean I don't have the "509" Or is it "506" block?

[More Power]

Cruzer,

I wrote that update about the uprated "1999" 6.5, that appeared in the 1999 Feature Articles volume (written in early 1999). That story was published before GM changed their mind. In fact - at that time, I received a matching water pump, 21" fan, fuel injection pump, and other uprated components that were slated for the "new" power specs. These plus discussions with GM Powertrain engineers were where the info came from. GM even carried those specs on their web site for a time.

We used the 21" fan and water pump on the TDP Power Project 6.5.

AM General may have done something differently... But, I don't have confirmation of that.

GM used several different block casting numbers from 1992-2000.

If I were buying a replacment block for a power project, I'd seek out a "599" or the newest version made since November of 2001.

MP

[ 11-19-2003, 01:11 PM: Message edited by: More Power ]

[Ralph Fichtl]

More Power, where would I look on the block to tell if it is a 599 block? Also can you list the the blocks and the year(s) they where made?

Thanks, Ralph