I am presently entertaining buying a "core" engine to completely rebuild with 18:1 pistons. However, I see that there are more 18:1 users here with troubles than without. Is this a coincidence? I know that this forum is a magnet for "problems" but I would think that MOST 18:1 guys would come here and hang out just to talk shop.

I am wrong about this? Is there an inherent problem with running the 18:1 pistons in the 6.5? My engineering "spider sense" is tingling, as I cannot fathom that a lower compression ratio would cause problems. I should state that the "successful" ones that I have read about (DieselP_ge.com and Peninsular) had mech. pumps...:shake:

Also, does anyone lower the CR by cutting the "bowl" in the piston crown as opposed to lower the compression height? This is the way I want to go (larger piston bowl)...

Any thoughts?

I think that the troubles here revolve around WHO and HOW the engine was built as well as choice of components OTHER than the pistons.

My psitons have volume added to the crown rather than "sinking" them down the bore.

Well, I am not having any problems with mine except it am getting bad mpg (12-15 compared to 18-20) and my A/C compressor went out. I love the truck after the engine I got from Peninsular. Lots-o-power and big smiles when pullen my race car around. I was finally able to pull my buddies F-250 across a parking-lot when we hooked chains together:ro).

I have not been driving mine though due to diesel price increase and the A/C compressor being out. Rather get 42MPG with my diesel VW rabbit.

But that has given me a chance to install the 24X12X4 intercooler that I got which I need to post pics for, it is an awesome looking aluminum monster (notched the frame to clear it).

But all in all, the truck runs great. No oil burning, starts up quick, pulls nice, sounds AWESOME, lots of turbo wistle. I am just looking around now for a Holset HX35W turbo with an electronic waste gate. That is the last thing for now.

My input on my 18:1

I think that the troubles here revolve around WHO and HOW the engine was built as well as choice of components OTHER than the pistons.

My psitons have volume added to the crown rather than "sinking" them down the bore.

I wasn't the WHO or HOW that built mine. Just wanted to make that clear.

I wasn't the WHO or HOW that built mine. Just wanted to make that clear.

Not being a smarta$$, but do you know what went wrong in your engine?

I have been watching the thread about your trials and tribulations with your engine and can add that dyno'ing the engine early (in and of itself) should not have hurt it. I build high performance competition agricultural engines (that's right tractor pulling engines:rolleyes: ) and dyno these from run time 0.000 hours. You just have to know "how" to dyno a fresh engine...

Wishing you the best with your situation..:exactly:

Didn't take it as you being a smart*ss. Won't know what really went wrong until DAS gets it in a week or so. If i had to hazzard a guess it would be the oil cooler being cleaned rather then replaced, but thats just my opinion.

Luv watchin the tractor pulls too!

My 18:1 failure was due to a pinhole leak that developed in the head which filled the #1 intake runner full of coolant while parked. This hydro-locked the #1 and bent all kinds of stuff.

The truck ran extremely well for over a week before this happend, and I had to drive it a couple of days after, and it still ran very well. It'll still start and run, and in fact, its being driven to the shop on friday for its new engine.

I belive that no engine builder would have caught this. It was a casting problem, and it was undetectable using normal methods before it let go.

18:1 are a good thing, provided you use them as part of a package (air, boost, fuel, cooling, exhaust, etc) rather than simply a 'stand-alone' performance part.

Tim

Didn't take it as you being a smart*ss. Won't know what really went wrong until DAS gets it in a week or so. If i had to hazzard a guess it would be the oil cooler being cleaned rather then replaced, but thats just my opinion.

Luv watchin the tractor pulls too!

So do you think the cooler was not dumping enough heat or do you think it got plugged?

My 18:1 failure was due to a pinhole leak that developed in the head which filled the #1 intake runner full of coolant while parked. This hydro-locked the #1 and bent all kinds of stuff.

The truck ran extremely well for over a week before this happend, and I had to drive it a couple of days after, and it still ran very well. It'll still start and run, and in fact, its being driven to the shop on friday for its new engine.

I belive that no engine builder would have caught this. It was a casting problem, and it was undetectable using normal methods before it let go.

18:1 are a good thing, provided you use them as part of a package (air, boost, fuel, cooling, exhaust, etc) rather than simply a 'stand-alone' performance part.

Tim

CowR

So were these heads "new to you" or were they rebuilt heads from a previous engine of yours? I am trying to discern whether increased cylinder pressure (from more fuel and boost) caused the pinhole or if this was a casting flaw from the get-go. If it occurred under power (had this happen on tractor puller heads), maybe I should consider ultrasound testing prior to installation?

Your thoughts?

I'll have a 18:1 complete engine for sale soon......

CowR

So were these heads "new to you" or were they rebuilt heads from a previous engine of yours? I am trying to discern whether increased cylinder pressure (from more fuel and boost) caused the pinhole or if this was a casting flaw from the get-go. If it occurred under power (had this happen on tractor puller heads), maybe I should consider ultrasound testing prior to installation?

Your thoughts?


These heads were new to me. The hole was in the intake runner, above the valve, so cyl pressure would not affect that area at all. Boost might have, but I adjusted the turbomaster down to about 10 lbs for break-in, so high boost would not be a factor. My money is on casting flaw.

A pressurizing test was done, but it would have not shown the problem as the hole took a week to develop. Some sort of exotic testing (x-ray, ultrasound, barium enema, etc) might have caught it, but those are not normally done on stuff like this.

Its most likely that the hole developed while driving, but it leaked so little coolant as to not be noticable. The real fun started when I stopped the engine, and it filled the intake runner with coolant.

Tim

So do you think the cooler was not dumping enough heat or do you think it got plugged?

Not sure only guessing here. I've talked with shops about this issue the most recent being where the engine is being pulled. They did some testing at some point in cleaning the oil coolers and found that washing em out with solvents, water, compressed air, whatever the method would still show metalic filings if filled with water shook up and around and drained again. I have not done this myself of course, this is just what i've been told. A new cooler would be cheap insurance IMO. That said i've also read somewhere, possibly a GM site, that if the oil cooler isn't replaced on a blown engine scenario the warranty would be void on the new engine.

I heard the same thing from a buddy of mine that races porches, CR. I never really believed that crap could be left behind and that it couldn't be cleaned but if he loses an engine racing he throws away the cooler too. And they ain't cheap.

went to cummins school in mid 80's, they tested back flush, reverse, back and forth, ultrasonic, hitemp and yes still had junk, told us to replace everytime. we used to test compressor hubs supposed to do at 2500 hrs, kept dropping til finally 500hrs, would dypenetrate(zyglo) magflux, UT and xray put back in engine and in about 20 hrs 1 out of 10 would explode, so not foolproof always.

Stay away from new 6.5 cylinder heads cast in China...

My Peninsular 18:1 is running great. It has been consistantly getting about 19mpg plus or minus a little. Peninsular recommends changing the cooler when you change the engine. The cost is minimal (compared to the engine), like $150.00. I changed mine.

My .02! I would do it.

HH65, you like the power you get? How bout those marine injectors, worth the $$$?

To be honest, I pitched my cooler and actually took out the lines and have not put a cooler back on yet. I got a BIG tranny cooler (universal) and am gonna put that on in a few days seeing as the truck has been sitting it will be a good time. But I never got a recomendation to get rid of my cooler but I knew from doing transmission coolers when trannies go out that the metal never leaves the cooler, especially that honey-comb stock cooler.

The oil cooler that GM used is the same style as the B&M supercoler. You can get them for a lot less from summitracing. The main difference is the B&M cooler uses pipe threads and the GM cooler used the o-ring seal. You could get adaptors and build custom lines. They also have a cooler one size larger(stock is 8X11 they have an 11X11).
http://store.summitracing.com/default.asp?target=partdetail.asp&autofilter=1&part=BMM%2D70266&N=4294924500+4294839034+4294888847+4294906639&autoview=sku

Yes, Power is good. I have changed the boost setting so I am getting a little more now. I have not towed with it since doing that. I'll report back when I do. Not sure on the marine injectors but got them for about the same as stock GM. It does tow better than before. It also seems to be less noisy at highway speed.

The cooler I installed was a Hayden. Made one hose and had other made at the auto parts store.