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Harmonics

John Romann said:
Turbo is a s366 with 6+6 billet wheel with a t3 .82 open scroll housing. Exhaust is nothing special, diamond eye crossover, downpipe modified with a 90 and 3 8nch vband to bolt to the s366 and their 4 inch exhaust without a muffler
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And that is the stuff that needs to go into your signature.
 
John Romann said:
Yes I know I'm new here. But I do know the ford Idi guys run very low pop pressures because they think the fuel actually makes it out of the precup and doesn't burn entirely making more power. Hence why my idea came up of ditching a precup design all together, maybe running 2500psi pop pressure and adjusting injection timing to make it run.
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Precups: better research has been and is being done for the IDI Mercedes. It's almost a lost art. Regardless this engine had a 100HP Economizer engine put in bread delivery vans/trucks. These engines had very small precups to generate high swirl above the piston to burn as much of the fuel as possible. The entire prechamber is just to get the dammed thing to actually start with primitive low pressure mechanical injection for a design vintage of 40+ years ago for just this engine. The prechambers also even out the timing variances that happen with the primitive by today's standards cheap to mass produce mechanical pumps. The precups actually hold heat and like a glow plug help evaporate and light the fuel.

A engine without prechambers is a DI diesel. To quote @THEFERMANATOR 'this was already done and is called a Duramax.'

Moving up from the small 100 HP precups... The Precups have limits. Too much fuel and air for a small precup means the swirl speed become so fast it centrifugally separates the fuel and air. So it doesn't burn and exits the exhaust as black smoke. Anyway we go powerwise up from civilian NA 6.2 precups, military emissions exempt versions, NA 6.5 precups, 6.5HO turbo precups, and the last and best Diamond GEP precups. The hole size and angle are big factors as well and any other ramps etc. in the airflow (flamethrower) nozzle. Go too big and MPG can drop like a rock. With a large free flowing turbo you may not always be on boost like cruising in town unloaded. So yes, there is such a thing as too big. Emissions, what little there were for this era, do matter to the design, but, no one cares about that now.

A few have worked with custom precups and 'too big' was found by others.

I have experimented with them out of ignorance and lack of funds to see what I could get out of 6.2 NA precups. Anything bigger than a GMx turbo with the fuel cranked to support it and NA 6.2 military precups just smoke black. Good turbo precups as your engine may have already had... @Will L. said it best there are other proven places to spend money for power.

On the left is a head with Military precups on a 1986 6.2, 3 bars. The cups sitting on the head are 1995 turbo precups, round dot. The head on the left is 1995 NA 6.5 precups, square mark. This just scratches the surface of all the precups GM made and the 'opinionated best for turbo' latest Diamond marked ones are not shown.

precups.jpg

One last thing: That would be YOU that has shit power not WE. o_O Plenty of power examples on here like one 6.5 that can run with a 395HP Corvette engine equipped Trailblazer SS down a 14 second 1/4 mile track. (Plenty of other modern diesels that can't even put it to the ground in lower gears.) Take a ride on one of our rigs that live up to the word "Performance" of this Performance Section and we will help you spend money to overcome that feeling... :greedy:
 
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WarWagon said:
Precups: better research has been and is being done for the IDI Mercedes. It's almost a lost art. Regardless this engine had a 100HP Economizer engine put in bread delivery vans/trucks. These engines had very small precups to generate high swirl above the piston to burn as much of the fuel as possible. The entire prechamber is just to get the dammed thing to actually start with primitive low pressure mechanical injection for a design vintage of 40+ years ago for just this engine. The prechambers also even out the timing variances that happen with the primitive by today's standards cheap to mass produce mechanical pumps. The precups actually hold heat and like a glow plug help evaporate and light the fuel.

A engine without prechambers is a DI diesel. To quote @THEFERMANATOR 'this was already done and is called a Duramax.'

Moving up from the small 100 HP precups... The Precups have limits. Too much fuel and air for a small precup means the swirl speed become so fast it centrifugally separates the fuel and air. So it doesn't burn and exits the exhaust as black smoke. Anyway we go powerwise up from civilian NA 6.2 precups, military emissions exempt versions, NA 6.5 precups, 6.5HO turbo precups, and the last and best Diamond GEP precups. The hole size and angle are big factors as well and any other ramps etc. in the airflow (flamethrower) nozzle. Go too big and MPG can drop like a rock. With a large free flowing turbo you may not always be on boost like cruising in town unloaded. So yes, there is such a thing as too big. Emissions, what little there were for this era, do matter to the design, but, no one cares about that now.

A few have worked with custom precups and 'too big' was found by others.

I have experimented with them out of ignorance and lack of funds to see what I could get out of 6.2 NA precups. Anything bigger than a GMx turbo with the fuel cranked to support it and NA 6.2 military precups just smoke black. Good turbo precups as your engine may have already had... @Will L. said it best there are other proven places to spend money for power.

On the left is a head with Military precups on a 1986 6.2, 3 bars. The cups sitting on the head are 1995 turbo precups, round dot. The head on the left is 1995 NA 6.5 precups, square mark. This just scratches the surface of all the precups GM made and the 'opinionated best for turbo' latest Diamond marked ones are not shown.

View attachment 52012

One last thing: That would be YOU that has shit power not WE. o_O Plenty of power examples on here like one 6.5 that can run with a 395HP Corvette engine equipped Trailblazer SS down a 14 second 1/4 mile track. (Plenty of other modern diesels that can't even put it to the ground in lower gears.) Take a ride on one of our rigs that live up to the word "Performance" of this Performance Section and we will help you spend money to overcome that feeling... :greedy:
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Don' get me wrong. Yes we can have quick trucks, but quick is the key word. And I should not have said shit power but comparing it to a modern diesel like my buddies 6.7l with moderate work. Yea it's depressing .
Realistically how much power can one make with the ds4 pump. I know most people who go for power switch to mechanical injection.
 
If you are on a smart phone then you can turn your phone sideways and it will show everybody’s signature.
 
Wow, never tried portrait until now. Yeah, lot of stuff disappears.

Something to consider- the 6.5 platform isn’t the best for everyone. Thats why many get dmax. Sometimes it is cheaper to go buy an old $5,000 dmax beater and rebuild it. I have seen some really fast ds4 trucks. But there is no way to match a db2.
It’s like saying you are going to stick with a gm turbo. You can improve it’s performance way better than stock, and there are some advantages you can use. But it you wanna run with the big dogs...

So a HUGE advantage imo of ds4 is the tie in with wmi computer controlled systems. You can do monster fueling, no added lag from cac making up for egt with it and the power from higher methanol ratios. The fastest ds4 truck I ever saw dumped 75% meth, and I mean DUMPED!
You have to set a realistic goal of power and learn what it takes to achieve it in build and money.

If you want power levels of the newer diesel engines, don’t expect it cheap.
 
I know it' not cheap. Realistically I know the 6.5l will only tickle the surface of what a moderate dmax or Cummins can make. But to go to dyno events or the sled pulls. I do want it to be interesting and show that the old girl still has some power.
 
biggest power hurdle by far IMO is fuel. I was thinking about the possibility of a mechanical IP but after reading about Nate's and WW's issues that pretty much rules that out for me
 
ak diesel driver said:
biggest power hurdle by far IMO is fuel. I was thinking about the possibility of a mechanical IP but after reading about Nate's and WW's issues that pretty much rules that out for me
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That' exactly my problem. Yes I know there' a ton of power to be made by going mechanical. But there' also a lot of headaches that can occur and realistically the shop where I work on the truck is 70 miles from my place cause of the damn leasing center. So that leaves 70 miles of praying nothing fails cause highway tows in ny cost too much
 
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