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Turbos and Mechanical 6.2s and 6.5 Questions

63chevyll

63chevyll

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Hello all.

Anyone have any experience with adding to a turbo to a 6.2 or 6.5 with mechanical pump?

My questions are...

How much did you turn up the pump and Was the adjustment at the pump enough

Marine Injections? Worth it?

Did you advance the pump?

Was the throttle response right away or was there still some lag

Did it smoke excessive? Black?

And last...boost and temps. Anyone monitor exhaust temp VS boost and load?


Thanks in advance, I'm messing with a 6.5 mechanical pump now. And plan on adding a turbo but starting from scratch
 
I've got a Banks turbo on my mechanically injected 6.2l with a 700R4 transmission.

On the original pump I'm not sure how much I turned it up in the end - probably about 1/4-turn or so. I played with it a bit until there was very little or no black smoke and the EGT and boost numbers looked good: max EGT under extended uphill load over mountain pass 1100˚F, EGT at cruise around 600˚F, boost at level cruise 1-2PSI.

Without overdrive the cruise EGTs would be lower, and downshifting is sometimes necessary pulling a big hill to keep EGTs under control.

I have stock injectors - they work fine.

Pump timing is set at stock spec.

There is some lag with this setup, but keep in mind that the Banks is not a wastegated turbo, and it takes some pretty high drive pressures to get it up and moving.

My 6.5l Burb has very little lag and runs consistently lower EGTs, but it's wastegated and has electronic injection.

If the Banks unit ever fails, I'll probably adapt a wastegated turbo in.
 
Longbedder. Thanks thats what I was looking for.

Bryan.. yes. But adding some fun stuff. Its a mechanical pump. I have it running on my test stand already.
 
63chevyll said:
Longbedder, how much peak boost do you reach
Click to expand...
9-10 PSI in my mech 6.2l, 9 PSI in my elec 6.5l.

In the 6.2l, that's simply all the current setup will give. In the 6.5, I've got it set to max out there (I have a homemade wastegate controller based on an adjustable spring).

My current understanding is that 10 PSI is a limit which allows good engine longevity (head gaskets and bottom end). I just had the pan off my 6.2l to replace the rear main oil seal and there are no cracks at all in the bearing webs. I've been running the Banks for 8 years.

I think that the trick with these particular engines is high flow volume at relatively low pressure - that keeps EGTs down and gives the fuel plenty of oxygen to combust with, while taking it easy on mechanical parts. Keep in mind that the 6.2l/6.5l have really high static compression (even for a diesel) - too much boost will break things in a hurry. For reference, a 6.2l has a 22:1 compression ratio, while a 12V Cummins is 17:1.
 
Well . . .

longbedder said:
I've got a Banks turbo on my mechanically injected 6.2l with a 700R4 transmission.

On the original pump I'm not sure how much I turned it up in the end - probably about 1/4-turn or so. I played with it a bit until there was very little or no black smoke and the EGT and boost numbers looked good: max EGT under extended uphill load over mountain pass 1100˚F, EGT at cruise around 600˚F, boost at level cruise 1-2PSI.

Without overdrive the cruise EGTs would be lower, and downshifting is sometimes necessary pulling a big hill to keep EGTs under control.

I have stock injectors - they work fine.

Pump timing is set at stock spec.

There is some lag with this setup, but keep in mind that the Banks is not a wastegated turbo, and it takes some pretty high drive pressures to get it up and moving.

My 6.5l Burb has very little lag and runs consistently lower EGTs, but it's wastegated and has electronic injection.

If the Banks unit ever fails, I'll probably adapt a wastegated turbo in.
Click to expand...

I have the same setup, but even under heavy acceleration I can only get to about 5pds of boost, is your 10 figure with a heavy load (I have not done that yet, just got mine)?

Also, where your Banks system's air intake opens (mine is at the top right of the grill), do you have a deflector plate (to stop water from splashing in)? If not did you get rid of it? And how has that helped the boost if at all?

Per the OP good answers here so far, see more at this place, it's all about 6.2's and 6.5's:

http://www.thedieselpageforums.com/tdpforum/index.php
 
I can hit 10 PSI on flat ground with no extra load just by stomping on it and holding it. It will peak briefly at 10 just prior to upshifting into each gear in that case. I can get it to sustain around 10 pulling a steep grade or pulling a heavy load, but usually have to back off or downshift after a bit because the EGTs will eventually creep up. I'm talking mountain passes miles long that you won't find anywhere around Florida.

I have the Banks air cleaner box just open at the front - I never had it connected to anything so I can't really compare it to being hooked up to the baffle. I also have straight pipe with no muffler or cat from the turbo back (although the Banks muffler is pretty open and shouldn't really cause a problem).

I can only get to about 5pds of boost
Click to expand...
I'd first suspect either a leak somewhere between the turbo and the heads or a restricted exhaust.
 
Cool. I have a waste see for 10psi. And I was worried if that was too much. I know some people on different forum's say dont ever run over 20psi. And im going keep 10 or less.

But after today im looking at twins. I have the headers built and turbos on the bench.

They are small enough to have good low speed air flow and not have too much wasted boost. Meaning not having th waste gate open all eth time
 
longbedder said:
I think that the trick with these particular engines is high flow volume at relatively low pressure - that keeps EGTs down and gives the fuel plenty of oxygen to combust with, while taking it easy on mechanical parts. Keep in mind that the 6.2l/6.5l have really high static compression (even for a diesel) - too much boost will break things in a hurry. For reference, a 6.2l has a 22:1 compression ratio, while a 12V Cummins is 17:1.
Click to expand...


Those compression numbers are kind of a non starter issue. When you consider the number of people pushing 50-60psi on top of that 17:1.

My person best is 75psi from an 88mm HT4C into my first 24valve. Which might have been around 17.5:1 stock.
 
I would be curious to see how a fully built 6.5 would perform with 75 psi over the slugs.
But then again..why.
 
Oh no doubt. Who knows what they would take forged Oringed and studded.

I was just making reference to the compression ratios versus the psi boost.

17:1 22:1 it doesn't make a lick of difference.
 
17:1 means a 17 multiplier of compression - for a naturally aspirated engine that means 250 PSI. If you're running 50PSI of boost, the compression ratio doesn't add to the boost number, it mutiplies it to 1100 PSI (for a perfect engine).

You run that same 50 PSI of boost on a 22:1 engine, you're now talking 1423 PSI (30% increase).

These numbers translate to significant differences in mechanical stresses. There's also a reason engine manufacturers dish pistons and drop compression on diesels if they're going to add boost.
 
I don't follow your math there. But the versions I was referring to are 75 psi on 17:1. And 10 psi on 22:1.
 
DEMON44 said:
I don't follow your math there. But the versions I was referring to are 75 psi on 17:1. And 10 psi on 22:1.
Click to expand...
Atmospheric pressure is 14.7 PSI, boost pressure gets added to that. Then the piston squeezes it and multiplies the incoming charge pressure by the compression ratio.

For example, at 50PSI boost and a CR of 17:

(14.7PSI + 50PSI) * 17 = 1100PSI static cylinder pressure

It's not a perfect number due to valve timing, blowby, etc., but it's pretty close.
 
For some Reason my calculator wasn't working last night. Must have been the operator.

But it reinforces exactly what I said. Putting 10psi on top of 22:1 is hardly hurting it. When 75psi on 17:1 can eat all day.
 
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