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250hp and 500ft/lbs from a 6.2?

K

K5dreamer

1/2 ton status
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Hey all, im just curious, what do you think it would take to get 250hp and 500ft/lbs from a early design 6.2L? and preferably keep the 16/22 mpg that it gets now.

Ive looked over the engine and the specs on it, and for the life of me cant figure out why the power ratings on these engines suck so bad.

only thing i can figure is that either the heads, cam, fuel pump, or combination of the three are a cork in the system. has anyone heard about maybe swapping the 6.5L cam in if its different, maybe porting the heads, putting in high flow valves, or if there is a higher flow, or higher pressure pump available?

the engine has a 21.5:1 compression ratio, and large displacement, and should be able to post some decent numbers. Even a turbo'd 6.5L with smaller port heads and lower compression can put up 200hp and 450ft/lbs.

ive sent an email off to GEP, who make the optimizer 6500 for the hummer, but havent heard back from them.

diesel power magazine is doing a buildup on a turbo 6.5L that im looking forward to, but i was curious what feedback id get on here.

I was thinking a banks sidewinder turbo, and a set of high flow valves in the heads, but was curious as to cam options, and maybe some other tricks yall might know about for these engines like swapping parts from a 6.5L, or high performance injectors, to help me meet my goal.

course, these power levels might just not be possible from this engine, i realize its never gonna be a 800hp 1000ft/lbs monster, but it would be nice to have more power than my buddy with a stock jeep cherokee :doah:
 
i remember seeing a dyno sheet online of a 6.2 pushing 240hp/450tq at the wheels, which is more power than you mentioned, so it doable, you just need the right parts. it was definitely with the banks kit
 
Main thing is a turbo kit. That will wake it up more than anything and make it feel like a real diesel. Having 21.5:1 compression really hinders this engine. I thought I read that there are some aftermarket pistons that lower the compression around 18.1:1 or so. The much lower compression would really help out power and can remember of guys then being able to really put some fuel and air to this engine with different pistons.

Never heard much of a problem with the flow of the heads, swapping cams from a 6.5 should likely yield basically nothing. Cams don't effect diesels nearly as much as they do in a gas engine.

I think Joez had 6.5TD injectors in his 6.2, maybe he can post up and give you some info about bigger injectors.

You could always take the stock injectors in and have them extrude honed, run them through once and they will be able to dump a fair bit more fuel.
 
because you can put more boost in the cylinders to get more fuel & air in the motor. With 21.5:1 you can boost only about 6-8psi before you worry about blowing the head gaskets. A Cummins (stronger motor obviously with less compression) can boost up to 35-40psi before headgaskets are a problem.

More boost=more fuel & air
More fuel & air=more power

Harley
 
colbystephens said:
why does lower compression increase the power?
Click to expand...

Boost from a turbo really heats things up. Higher compression compounds this, if its slightly lower then you can pump more boost into it and add more fuel for more power.
 
the compression / boost situation has me confused as well. arent we talking about cylender pressure right? so regardless of boost and compression, if the ending pressure is the same, wouldnt the overall boost and performance be the same? i dont know alot about turbo's or diesel so im not trying to call anyone out or challenge, i really just dont understand.

as for the larger injectors and whatnot, wouldnt that wind up costing me fuel mileage? or becaues diesels are fuel throttled, would my mileage onily drop if i was heavy on the gas.
 
Adding boost adds cylinder pressure, so more boost = more pressure. So adding boost to a high compression motor can increase the cylinder pressure above what the motor can handle. If you reduce the compression ratio you can add more boost, but still be in the safe area for the motor. By adding boost you are adding more fuel & air to the cylinders so you can make more power.

More boost = more power

Harley
 
Cylinder pressure does not equal power. The amount of fuel & air you can pack in the cylinders equals more power. Packing air & fuel into the cylinders is done by adding boost.

Harley
 
K5dreamer said:
as for the larger injectors and whatnot, wouldnt that wind up costing me fuel mileage? or becaues diesels are fuel throttled, would my mileage onily drop if i was heavy on the gas.
Click to expand...

That is a tightrope. I am not familiar with the GM diesels as much but I do know some about the Cummins and from what I know here goes.

Small performance injectors for a CTD can actually add mileage as long as you drive normally. Once you start to get into the larger injectors then you will start causing yourself mileage.

Harley
 
Even driving a turbo'd 6.2 'normally' you'll still give up some fuel mileage due to the restriction of the turbo...

If you're hoping for outright economy I'd leave it NA.

Rene
 
I have a 325hp/500ft.lb.+or- 6.5TD.It runs 18:1 compression,a modified DB2 pump,Hi-pop injectors,a medium-duty Switzer non-wastegated turbo,intercooler,and hi-flow cooling system in a`92 K3500.Also,a custom elbow off the turbo and a mandrel-bent 3 1/2" exhaust(Banks).You can do all this to a 6.2,but with 19:1 pistons.If you have a 599 (last#s) block,you can bore to 6.5 and run the 18:1s.Check out www.peninsularmarine.com
 
super K, depending on tire size and gearing this may be a silly question, but what kinda mileage are you getting from that engine setup on the highway?

I did a little digging, and just for ****s and giggles ill throw it up here, check out this link for a story on modding a 6.5L TD. Theres no actual dyno info, but they claim to mod the 6.5L to run with the offerings from ford and dodge in the 1999 model year. In fact the 6.5L is claimed to be 2 seconds faster in 0-60, and get 17-20 mpg running unloaded on the highway with stock tires and 4.10 gears. heres the link...

http://www.thedieselpage.com/finale.htm

the power of the 1999 7.3L powerstroke was, according to the following link, 250hp/505ftlbs for the manual, and 275hp/520ftlbs for the automatic.

http://www.intellidog.com/dieselmann/power.htm

the power of a 1999 cummins, according to this link was, 230hp/450ftlbs for the manual, and 215hp/420ftlbs for the auto.

http://www.edmunds.com/insideline/do/Features/articleId=46028

In short, based on everyones comments, it does seem that the power levels of 200-300hp and 450-550 ftlbs are realistic, but you must....

1. lower compression to around 19:1 or 18:1
2. add a turbocharger with higher boost pressures
3. add an intercooler to cool the intake charge
4. high performance fuel pump
5. high performance injectors
6. and while not listed, probly adding a set of head studs to replace the weak torque to yield bolts would probly be a good idea to better withstand higher cylender pressure. especially seeing as blown head gaskets and cracked heads are a known problem for the 6.2L and 6.5L engines.

thanks for all your replys, its an interesting brain tease for me this weekend. and Rene, as always your input is appriciated, the turbo;s effect on mileage is something im concerned about, i just need to do some more research i suppose, ill have to wait to hear from GEP, and Penninsular marine, who i sent an email to today.
 
I get around 15 im a 8,000# truck with 285/75s,4.10s,and NV4500.Lee Swanger had a custom built N/A 6.2 bumped to 6.5 with other mods,mostly a huge filter housing w/dual cold air intakes,matched ports,and his own enlarged exhaust manifold couplers,that produces 200hp.His favorite saying is,"Don`t need no steenkin`turbo."
In`99 the mark to hit was 300hp and this is pre-Dmax.I like dropping Newbie diesel owners (most of them are) with my black smoke cloud in my low-tech soap-burner.I`ve got full arp hardware and lined water ports in my heads.The block is the post GM high-nickle/beefed main web GEP block.The Diesel Depot has a cam out.I think Lee Swanger runsone.They built his motor.For years the word was deck clearance was too tight for higher lift.Maybe with the low compression pistons play the match-maker in this.
Here`s another cool site: www.marinediesel.nu
This is the diesel work truck:
scan0017.jpg
 
Last edited:
Hossbaby50 said:
Cylinder pressure does not equal power. The amount of fuel & air you can pack in the cylinders equals more power. Packing air & fuel into the cylinders is done by adding boost.

Harley
Click to expand...
Basically in a nut shell, but since a diesel is fuel regulated and not air regulated like a gas engine (more boost equals more power under gas conditions), normally less compression, which allows for more overall room in the chamber, allows for more fuel, and boost that is then added later on top of the fuel.

As far as someone asking about fuel economy and injectors.

There are multiple ways of building an injector.

1. The best way is to build with a fresh nozzle and cut it EDM style with a lazer that burns a perfect hole(s) into the tip itself. This opens up for a lot of improvement, more holes than factory injectors helps add better atomization and along with changing spray angle and pattern can produce better combustion. All this works on making more power on the same amount of fuel with better mileage.

Now, more holes that are bigger can go towards dumping more fuel for more power.

2. Extrude hone, this is simple and can be done to nearly any injector. An abrasive fluid is passed through a factory nozzle and it simply wollows them out making them larger and smoother to simply spray more fuel. Since a diesel is fuel regulated and not gas regulated, your foot should control the amount of fuel injected and not allow much of a fuel economy change. BUT, when you want to use the power, lay into and roll the coal...:bow:
 
K5dreamer said:
In short, based on everyones comments, it does seem that the power levels of 200-300hp and 450-550 ftlbs are realistic, but you must....

1. lower compression to around 19:1 or 18:1
2. add a turbocharger with higher boost pressures
3. add an intercooler to cool the intake charge
4. high performance fuel pump
5. high performance injectors
6. and while not listed, probly adding a set of head studs to replace the weak torque to yield bolts would probly be a good idea to better withstand higher cylender pressure. especially seeing as blown head gaskets and cracked heads are a known problem for the 6.2L and 6.5L engines.
Click to expand...

You do realize that the 6.2 never came from the factory with a turbo, so it's really hard to compare it to anything that did come with a turbo including most 6.5 equipped trucks. I've driven Fords with a NA (naturally aspirated = no turbo) 6.9 and 7.3 and they are very doggy by today's standards also. I bet even a 5.9 Cummins with no turbo would feel like a complete slug (though I've never seen a 6BT application without a turbo....the engine was probably designed from the start to run one).
 
I don't know much about diesels but I've always heard that the 6.2 and 6.5 were horrible engines. This thread makes me think that a 6.5T might actually have potential to be a really stout engine. Heck if you can make 550 lb/ft at the wheels that's stout by any standard. Might make me rethink finding a truck with that engine.
 
there was a vid on here somewhere in a thread that a guy built a 6.5TD for his tractor for tractor pulls and it was badass. the 6.5's definitely have potential. ill try to dig up the video
 
tiger9297 said:
I don't know much about diesels but I've always heard that the 6.2 and 6.5 were horrible engines. This thread makes me think that a 6.5T might actually have potential to be a really stout engine. Heck if you can make 550 lb/ft at the wheels that's stout by any standard. Might make me rethink finding a truck with that engine.
Click to expand...

From what I have read(im no expert by any means) The 6.2 has been held with high regard as far reliability, but was lacking in power. The 6.5 had problems with the PMD but with the aftermarket this problem is easily fixed. I have a 6.2 in my blazer and a 6.5 in my crewcab. Both work great, though I would like to put a cummins in my CC :D
 
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