New heart for the Chevy

[Ozwynn]

Well I kinda see his point... but he could definately be less of a dick about it...

This actually looks like alot of fun (well to me because i don't get to wrench enough) Looks like you got yourself a good interesting project.

So the 6.2 will bolt up to your 6.5 tranny and everything? The 6.2L is a non turbo if I'm correct...? It is going to fair well with the turbo on it?

yep. the 6.2 will bolt right up to my 4L80e.... even going to use my 6.5 fuel system so I don't have to change the computer for 1 that just runs the transmission.... (although if I had the money and time to track down the parts I would run the military version of the pump used on mechanical 6.5T from the HMMWV, has bigger plungers)

this one is Naturally aspirated, I will be using 6.5T head gaskets (as the heads are the same.... infact the 6.2 has bigger valves)...... due to the crack I will be limiting the boost to a max of 10 psi and a sustained of about 6-7 psi..... but others have run 20 PSI on a 6.2 with 6.5 head gaskets with no problems. Will has a banks turbo'd 6.2 running 12 psi with no ill affects..... I have been following a build on a 6.2 running 40psi boost and his goal is 60 psi for a sled puller...... his engine is highly modified and is running 16:1 compression.... a stock 6.2 is in the 20.5:1 to 22:1 range (this is why a nastily aspirated 6.2 gets 22-26 mpg in a 3/4 ton 2wd).

truthfully I have no desire to put in a Duramax .... The IDI mechanical fuel system is more reliable and IDI will burn any old crap you can put in the tank......


now if I had a cherried pre '92 Crew Cab Fatback with no rust and a flawless interior I would be looking at maybe a GEP P400 optimizer (390 hp, 550 ft/lb torque)/ Allison 6spd or a first gen Duramax/ allison 1000.

 

[Original_Ranger84]

Hmm... thats what i was wondering cause since diesel ignites because of the compression i figure a turbo would put more pressure in the cylinder and cause it to prematurly combust.

 

[mn_smokeater]

what would happen if that crack let loose?

 

[Ozwynn]

it would make a big boom.

 

[mn_smokeater]

it would make a big boom.

ahh i see you simplyfied it for me

 

[Will]

Hmm... thats what i was wondering cause since diesel ignites because of the compression i figure a turbo would put more pressure in the cylinder and cause it to prematurly combust.

Diesel doesn't ignite because of compression. Compression Ignition is a misnomer. The compression heats the air to around 1,000F and the fuel is sprayed into the hot air, which causes the combustion.

It's not the same as a gasoline engine. With a gasoline engine, the fuel is unstabile and the compression can cause it to detonate because the fuel is being compressed with the air. In a diesel, the fuel is not being compressed with the air. The combustion temperature is the thing you want to watch in a diesel.

Keep in mind, too, that a 6.2 is an indirect-injected motor. it has a pre-chamber pressed into the cylinder head and the injecter sprays into that pre-chamber. The initial burn takes place in the pre-chamber and then forces the rest of the unburnt fuel out into the cylinder to complete the combustion. You need a little bit more compression to make sure the air is hot enough by the time it enters the pre-chamber, plus it needs glowplugs to aid in cold-starting. The indirect-injection motors are quieter because the combustion doesn't happen in one big sharp RAP as it does with a direct injection, mechanical motor without pilot injection.

The thing you watch on a diesel is the temperature of the exhaust--or turbine inlet. On a gas motor it's better to have all of the fuel and air molecules closer together when you spark them off. It's probably true on a diesel too. The maximum temperature is the thing you want to watch. Too much of it and parts melt. But it's the fuel on a diesel, not the air. You watch the temperature and turn down the fuel to reduce the temp. Having more boost reduces the temp, unless you use that air to burn more fuel.

So in my opinion, a high compression diesel with a little bit of boost is the most efficient use of an indirect-injection motor. It's 10% better than the no-boost version. Reducing the compression to reduce combustion temps and allow more boost and more fuel may mean hard starting and bad fuel economy. I'd almost bet on it. But if you are going to do 400hp with an indirect motor, you have no choice but to lower the compression.

Anything around 10psi is great with a 6.2/6.5 and a stock pump. It's enough turbo to burn all the fuel with the pump turned all the way up and doesn't smoke much. A little squirt here and there, but at full power it's pretty clean. I don't like smoke--it just means you have more fuel then you have engine to use. I can burn an old tire in my yard and get more smoe than you can dream of, but it's not cool. Past 10psi, the air needs to go through an after-cooler because it's too hot and the air molecules are too far dispersed to increase oxygen. The air going into the engine is at about 350F at 10psi. You won't have 10psi after the cooler, but you will have thicker, denser oxygen and more power.

 

[Sevensecondsuv]

BDAB, I'm just wondering what you need a 3/4 ton for that it's worth putting 2-3 grand to fix the engine and upgrade the tranny? I mean, 2-3 grand will buy you a pretty nice 4 banger Ranger that doesn't need any repairs and still has a useful bed and gets 20 to 30 mpg.

Not trying to crap on your project or thread, just wondering why you need a big truck?

 

[Ozwynn]

BDAB, I'm just wondering what you need a 3/4 ton for that it's worth putting 2-3 grand to fix the engine and upgrade the tranny? I mean, 2-3 grand will buy you a pretty nice 4 banger Ranger that doesn't need any repairs and still has a useful bed and gets 20 to 30 mpg.

Not trying to crap on your project or thread, just wondering why you need a big truck?

this is long an complicated....... I would rather have a Diesel Suburban....... but it comes down to, the Sidekick isn't really big enough for all of us. The extended cab Chevy is .... it will seat myself and my wife, all 3 kids and the dog.... and i need a 9000 pound towing capacity 4 or 5 times a year...... the Chevy when it runs gets 22 - 24 mpg, good enough to use as a daily driver and can handle 9000 pounds.

 

[Ozwynn]

this is an example of the valve train I want to set up. These are BBC 1.7:1 roller tipped stainless steel rockers with the trunnions drilled out so they fit on the rocker shaft. I think with mine I will just use the stock shaft with aluminum spacers instead of a custom machined shaft with clips ......

these were built by Max PF at CK5.com. the pics are courtesy of the current owner of the engine at TTS.

I'll try to get specs on the set up posted if anybody is interested ... mostly its technical stuff on the materials and dimensions.

 

[mn_smokeater]

ohh it makes much more sense to me now looking at it!

 

[Will]

What for?

That's a waste of money.

I've owned this truck for 6 years. Lots of power, good mileage and the only thing I've done is replace a waterpump. Same Optima batteries, even. I've pulled trailers from Colorado to Florida to Massachusetts. It's been my daily driver for 5 of those 6 years. 300 miles per week.

Roller rockers on an engine that never spins past 3,000rpm and spends most of it's time at 2,000?

 

[Ozwynn]

What for?

That's a waste of money.

I've owned this truck for 6 years. Lots of power, good mileage and the only thing I've done is replace a waterpump. Same Optima batteries, even. I've pulled trailers from Colorado to Florida to Massachusetts. It's been my daily driver for 5 of those 6 years. 300 miles per week.

Roller rockers on an engine that never spins past 3,000rpm and spends most of it's time at 2,000?

you have a point, I won't deny that. I took the rocker assemblies off my 200,000 mile engine and it showed no wear..... except on the plastic alignment caps..... ofcourse mine was overheated far enough to crack the heads..... and on the motor I am putting together to get this pig running will not get this head treatment.....

This will be for my Version of the P400 (minus the CAT electronics) .... my goal is 300 rwhp and 500ft/lb rwtq..... Looking at the stock rocker (eyeballing) they appear to be 1.3:1 ratio. I know it can be done with out drugs, I have seen them, and their dyno results.... and this engine won't be going into this truck ....... probably a 91 or Older Crew Cab dually......

 

[mentalbreakdown00]

Just wanted to make a comment that evey 6.2/ 6.5 that I have ever seen has 2 problems. One the wiring in the engine compartment I have seen break many, many times (as in the wires vibrate and the circuit becomes open). Second is that evey 6.2/ 6.5 I have ever seen cracks heads with just even a smidgen of over boost, so what youself on that one...

 

[Ozwynn]

I am going to case the wiring harness in heater hose. and I am only going to run 10psi boost max .... 6-7 sustained.

The problems with head cracking due to over boosting was fixed with the Optimizer 6500 and the Optimizer P400 ....... those are running 20-25 psi and 20:1 compression no problems...... head studs also help out..... not going to use them on this build.

The problems I am having is every block i look at is cracked in the main saddle......... on the thrust bearing main.

 

[TheTopher]

Lots of good info in this thread. Keep it up BDAB, my favorite threads are the ones I learn from.