So from the collective, what is a safe upper limit for boost?

When I got my truck ('93= no pmd etc..) the spring loaded boost controller was frozen closed and stayed that way for some time. It eventually broke loose and all I could get was about 8lbs on the Banks Dynafact. I decided that it had run a long time frozen closed, so I took it off and wired the wastegate shut, completely!

I regularly peg the boost gauge out (15psi) and at interstate speed, it stays above 10. More when towing, and untill I added some fuel via the IP screw (1/8 turn) never saw egt's above 700. I have not towed the big trailer since, but the car trailer with the TDI is about 7k+ and I got it up to 800. It does seem to rise a little quicker now though.

My question is this, as long as the egt's are in check will I be ok at over 15psi of boost for extended periods? I have pulled the 12k lb travel trailer about 70 miles down the interstate at 60mph (before ip fuel adjustment) and the boost stayed pegged except for the slight downhill runs.

20k miles ago, I replaced the head gaskets and installed NEW head bolts.

Pics of boost and egt before IP fuel adjustment:
http://www.dieselplace.com/forum/showpost.php?p=3795033&postcount=132

Insert valued opinions here:

Anyone?

I'm not real familiar with the non electronic 6.5s, but If its not blowing any smoke, you shouldn't need any more boost. I dont think id go over 15 psi tho, atleast not without an intercooler. If it was me, id make my own boost controller and tighten it down to 15psi and check for smoke. If there is none (and i doubt there will be) then id back it off until it smokes a bit and then increase it again by 1 to 2 psi.

I think 15psi sustained is too much. 15 for short periods of time and 10 constantly sounds about right to me.

I'd have to ask what advantage is there to all that additional boost like why push it that hard for what? It ain't gonna make any more power from air alone...

15 i think is too much for extended periods, these tty bolts have a hard enough time handling stock boost and i would expect you to go through head gaskets at that pressure

I would assume 18 psi would be a max for a well equipped 6.5L with all the bells and wistles. But in my truck I would probably make a 13 or 14 psi max. But if you wanna play with it go ahead. Just don't blow it up. That would be wery wery wery bad..

Well, I guess I found out how long you can run that much boost. got the fam and the rv all loaded for a two thousand mile vacation. made it nearly two hundred miles before blowing numbers two and three main caps off the bottom of the block. Not a pretty sight. I ordered a new motor from u.s. engine rebuilders(?) out of New York. I thought was a fair price at 3700 for all new internals and new head castings and a new block. We shall see. It was officially themes expensive vacation we have taken yet. I think I will dial the boost down a tad now.

how much boost were you running? I wouldnt go over 13 or so without an intercooler i dont think.

With an Intake air temp gauge, you will see very high IAT with boost levels above 8-10 pounds unless you have an intercooler or outside air temp is low. IAT will climb faster than EGT. High IAT and EGT are warnings. Your recent blown headgaskets were also a warning that you have too much boost.

what is recommended boost with an intercooler?

http://www.thirdgen.org/techboard/images/smilies/search.gif

It's your friend. You'll find all the information you'd ever need right here.

http://www.dieselplace.com/forum/showthread.php?t=53309

You should be able to run 14-15 lbs of boost with an intercooler. That is, if you can provide the fuel as well, otherwise you're wasting your time.

Jake

What pump are you running in your truck? The 6.5L in that era ran a DB2831-4911 pump that can delivery enough fuel for just about any well built 6.5L.

We run at 20psi, intercooled, water/meth injection, HE 351vgt turbo, Cometic multi layer head gaskets with ARP studs, custom main bearing girdle...... got just over 1200 miles now (hoping for 10,000).

We do our own work, so this build cost less than $4000.00 cdn.

Do you plan on doing a girdle or thicker head gaskets with your new motor?