305 vs 6.2L diesel

[jarheadk5]

...if you have a 300hp 350 and drop in a turbo, you'll have a 600hp 350 when the stall kicks in on the turbo...

That's like saying "if you put a cam with .700" lift in your stock 350, you'll double your power". Uhhh, NOT. The rest of the motor has to be built to accomodate that power-adder. And what the hell is this "stall" that kicks in on the turbo??

...if you put in a twin turbo setup, each with 15 lbs of boost, you have 30 lbs of boost total... run one for low/midrange rpm, and the other for midrange/high end rpm, or both for full range, and you will have a 350 pushing nearly 900 hp for about the cost of a _NEW_ 6.2L diesel... stock....

Go ahead and put twin turbos on a stock 350. Set them up for 30lbs of boost. Put that motor on a dyno, set up a webcam, and invite us all to watch. I'd love to see what 30lbs of boost would do to your stock 350...
And as far as cost goes, the last twin-turbo'd SBC I saw (in a magazine; never seen one in person) dyno'd at 1100hp and had a turn-key price of $50K.

... turboing a SBC is just as effective on gas mileage as turboing a diesel....

Really? So why, in a time when auto manufacturers are being pushed hard from every direction to improve fuel economy, are turbochargers not found on every gasoline engine?

 

[nascarjohn24]

6.2l

I would go with the 6.2 because It will last longer and I had some (alot) troubles with the 305.

 

[tRustyK5]

It costs me $17 to rebuild my Quadrajet.
I have $700 into my rebuilt 305 and the dynosheet started at 2250rpm and was already beating the diesel in horsepower and torque. I know below 2,000 the diesel kicks its ass but so does a 350. You can definitely tell it's a 305 at low rpm.

I got ~11mpg towing my project rig with my 305-powered pickup at 65-70mph. She was spinning around 3,000rpm the whole time. Unloaded I get around 16mpg (usually 31-32 gallons to go 505 miles half of which is expressway and half of which is regular roads) on the highway with an average speed of 63mph. Around town I get like 1mpg but I drive kind of hard.

The last time I priced 6.2L injectors and pump it was just under $700. Apparently they're cheaper now?

You have to shop around...I'm glad I did.

Do you get 16+ mpg on bias ply 40's with your 305? How about 15.5 mpg in town on 40's? How about 23 or more mpg possible just by lowering the cruise rpm to ~1900 rpm?

About the only time my 350 ever pulled harder than my 6.2 was above 3500 rpm. Cam was a conservative CC 260HE. The tq peak for a 6.2 is 2000 rpm and the last dyno sheet pic I posted showed 359 lbs of torque to the rear wheels for a NA 6.2. Once the Banks kit was installed it made 451 lbs of torque at the rear wheels. I'd really love to see the stock SBC that can match those numbers...hell, I'd love to see a modified sbc put down those numbers. It'd cost you a hell of a lot more than $700 and the tq peak would be at a pretty high rpm.

Oh yeah, the 6.2 will run at any angle...unlike a carb'd gas engine. That sure makes wheeling a lot more fun for me.

Rene

 

[tRustyK5]

I said that because thats the only gm diesel from 88-98 that came with a turbo which means that any other turbo diesel should be out of the question when it comes to the bbc vz diesel debate. whether it be a 6.2 or 6.5 is going to need a kit for a turbo(Unless it was the rare 6.5TD that was offered for 2 years) which means $$$$. You can do the same to a 350 or 454 for close to the same cost.

All I'm saying is that if you start with a stock 6.2 or 6.5 and pair em up with a 350 and a 454 then do the same mods to em the gas will make more power(6.2 turbo vs 350 supercharged and 6.5 turbo vs 454 supercharged). Once again im not knocking deisels but whenever the gas and diesels are compared everybody wants to bring up that if you turbo the diesel it will make more power...no sh$t. turbo or supercharge the gas and then compare em...

If your going to say that the supercharge is an advantage over a turbo its not... turbo is free hp, supercharger takes hp to make hp, but then you have turbo lag. damn this is getting to be a can of worms

So, what kind of longevity and fuel mileage would you expect from a supercharged small block?

 

[smalltruckbigcid]

I have friends who are running hotshot diesel pickups around the country and they are knocking down 400,000 miles to the first overhaul. One guy did that number in 32 months driving it by himself. Don't get me wrong, gas engines have their place, but it ain't doing a long haul pull the guts out of it boogie down the highway for weeks on end.
George

 

[mcinfantry]

granted its no 6.2 but my 105hp cummins 4bt is a good motor vs a 350.

i have almost 200 foot pounds of tq at 1000rpm. i can wheel all weekend and burn 5 gallons of diesel vs 30~60 gallons for the gassers.

anyone have a turbo's 350 or 454 dyno sheet at 1000rpm? im curious what the specs are. ill post my dyno sheet if anyone wants to see it

 

[rugger03]

I said that because thats the only gm diesel from 88-98 that came with a turbo which means that any other turbo diesel should be out of the question when it comes to the bbc vz diesel debate. whether it be a 6.2 or 6.5 is going to need a kit for a turbo(Unless it was the rare 6.5TD that was offered for 2 years) which means $$$$. You can do the same to a 350 or 454 for close to the same cost.

All I'm saying is that if you start with a stock 6.2 or 6.5 and pair em up with a 350 and a 454 then do the same mods to em the gas will make more power(6.2 turbo vs 350 supercharged and 6.5 turbo vs 454 supercharged). Once again im not knocking deisels but whenever the gas and diesels are compared everybody wants to bring up that if you turbo the diesel it will make more power...no sh$t. turbo or supercharge the gas and then compare em...

If your going to say that the supercharge is an advantage over a turbo its not... turbo is free hp, supercharger takes hp to make hp, but then you have turbo lag. damn this is getting to be a can of worms

Actually all of the GM light duty pickup trucks, blazers and suburbans that came with a 6.5 were turbo'd from the factory after 1993. If i recall correctly Gm also offered the banks turbo as an option from 89-92 6.2's.

 

[joez]

Actually, id love to see your dyno sheet, because i am planning on replacing my 6.2 with a 4bt. I had a 105 hp 4bt dyno sheet here somewhere, but lost it when my computer crashed.

 

[mcinfantry]

no problem, its posted here http://homepage.mac.com/ltalessi/PhotoAlbum89.html

josh (bowtieblazer) and i are putting a 4bt in his 86 blazer. the tub is off, and we are making some headway

 

[dyeager535]

I think it's pretty uncommon to see dynos that start under 2000RPM. Even Desktop Dyno starts there, but engine analyzer does show lower, and those are just calculations...why they both can't be 1000RPM+ or whatever, no idea. According to DD2K, my 355 puts down 400+ ft lbs at 2000RPM and starts dropping. I don't buy into that necessarily, but pretty hard to compare REAL low end (which is very important for wheeling) when even the "fake" dyno won't show under 2000RPM.

As to a turbo being free power, restricting the exhaust is not free. Any restriction costs power. Varying amounts, but it's still a restriction. Turn a pulley or put an impeller in the exhaust stream.

 

[Aquaman]

RPO-LF3 305/V8(CA) 155HP 240/TORQUE K10 ENG. 81 TO 86

RPO-LH4 379/V8(DIESEL) 135HP 240/TORQUE K10,20,30 ENG. 1982

IT's coming from a pretty reliable source too, but my question is: dont a 6.2 diesel outrun a 305 for torque?

I know the 6.2 will get that torque around 1500-2000 rpm but still same max. torque output!!! lol

one word: POWERBAND!!!!

 

[grape]

with as clueless as most of you sound about turbo's and gas engines, I'll race you with my homebuilt 6.5 turbo junk any day.......verses your gas junk

 

[grape]

Funny thing about turbo diesels is that they require so much more boost for the same power increase as a turboed gas v8... at 15 lbs of boost on a single turbo, a v8 will double it's total horsies... if you have a 300hp 350 and drop in a turbo, you'll have a 600hp 350 when the stall kicks in on the turbo... if you put in a twin turbo setup, each with 15 lbs of boost, you have 30 lbs of boost total... run one for low/midrange rpm, and the other for midrange/high end rpm, or both for full range, and you will have a 350 pushing nearly 900 hp for about the cost of a _NEW_ 6.2L diesel... stock...

You'd need something like 90psi of boost on a 6.2 diesel to get to 900 hp, and mind you, the boost affects torque too, but I don't know how much...

Plus... turboing a SBC is just as effective on gas mileage as turboing a diesel... you'll pick up some good mpg with either one...

this one takes the cake, I need to let my buddys on www.turbomustangs.com take all that info in. For the safety of your vehicle I'm gonna have to ask you to kindly step away from your tool box, lock it, and throw away the key.

 

[mcinfantry]

with 38's, 4.56 gears, 2 to 1 transfer and an nv4500 in second, at IDLE i can let off the clutch and climb almost anything and my foot off the clutch and off the gas. i use the brakes to control ascent.

until you wheel with the control of a diesel at idle, its hard to understand.

 

[CyberSniper]

You have to shop around...I'm glad I did.

Do you get 16+ mpg on bias ply 40's with your 305? How about 15.5 mpg in town on 40's? How about 23 or more mpg possible just by lowering the cruise rpm to ~1900 rpm?

About the only time my 350 ever pulled harder than my 6.2 was above 3500 rpm. Cam was a conservative CC 260HE. The tq peak for a 6.2 is 2000 rpm and the last dyno sheet pic I posted showed 359 lbs of torque to the rear wheels for a NA 6.2. Once the Banks kit was installed it made 451 lbs of torque at the rear wheels. I'd really love to see the stock SBC that can match those numbers...hell, I'd love to see a modified sbc put down those numbers. It'd cost you a hell of a lot more than $700 and the tq peak would be at a pretty high rpm.

Oh yeah, the 6.2 will run at any angle...unlike a carb'd gas engine. That sure makes wheeling a lot more fun for me.

Rene

235s or 33s and 3.42 gears. The best I ever got was 19mpg and that was with wiring the secondaries shut. I'll let you know when I get my fool-injected 305 going on its 40s and 3.73s. I bet the diesel won't come out that far ahead in mileage.

Can you start your diesel at 10°F and leave within 30 seconds without plugging it in overnight?

You do know that a TPI350 makes more torque EVERYWHERE than a 6.2L, right? Same goes for a LS1. An LS2 makes what that Banks 6.2L makes... stock.

My $700 305 will eventually end up getting pulled out of my truck, swap the XE262H cam that's in it now for something computer friendly, and put into my wheeling rig. I'm willing to bet it'll do as good if not better than a stock J-code 6.2L... without the stench.

A turbocharged diesel has its uses... but a 6.2L is not a turbocharged diesel. Your generic run-of-the-mill 70s LS9 350 made just as much power in all the same places as your run-of-the-mill 6.2L.



As far as other people and forced induction with a gasser... GM has been using them for 20 years now. So has Ford. Depending on the computer, you might not even have to do anything to go forced induction. It can be cheap as well... everyone knows about the twin turbo 302 setup that costs $3500. But that's a gofast setup. You need a whipple or a roots to get low-end.

 

[tRustyK5]

with 38's, 4.56 gears, 2 to 1 transfer and an nv4500 in second, at IDLE i can let off the clutch and climb almost anything and my foot off the clutch and off the gas. i use the brakes to control ascent.

until you wheel with the control of a diesel at idle, its hard to understand.

I wheeled almost everything in Moab with both feet flat on the floor, the only time I used the throttle I pretzeled the driveshaft (dented the tube on a rock first)

Crawling with a diesel and a manual tranny makes it all look elegant and in control...there is nothing like it. In comparison my 350 was a PITA to wheel with.

Rene

 

[joez]

Can you start your diesel at 10°F and leave within 30 seconds without plugging it in overnight?

You do know that a TPI350 makes more torque EVERYWHERE than a 6.2L, right? Same goes for a LS1. An LS2 makes what that Banks 6.2L makes... stock.

Yes, i can. As soon as the glow plugs stop cycling i put her in gear and drive away. Normally takes less than 30 seconds, a lot less.

I love your LS2 comment, lets compare something made over 20 years later with an IDI diesel.

As for fuel economy, at 230K miles, with bias ply 36's and 3.73's i still see over 20mpg.


I cant type anymore, im stopping while im ahead. I dont know what to adress next without my head exploding, some of you really are clueless, no offense.

 

[Pookster]

huh? Rene and others get better than 15mpg with their 6.2s and low gearing. I don't know about you, but I've never done better than 10 mpg with any of my gas motor K series trucks.

You misunderstood. I was referring to thetons of other posts about people with 305's and 350's who try to gain 1mpg, but spend hundreds to do it.

 

[tRustyK5]

Yes, i can. As soon as the glow plugs stop cycling i put her in gear and drive away. Normally takes less than 30 seconds, a lot less.

I love your LS2 comment, lets compare something made over 20 years later with an IDI diesel.

As for fuel economy, at 230K miles, with bias ply 36's and 3.73's i still see over 20mpg.


I cant type anymore, im stopping while im ahead. I dont know what to adress next without my head exploding, some of you really are clueless, no offense.

I'm done too...it's getting as stupid as the auto versus manual threads we all love to hate.

Rene

 

[Pookster]

I dunno rene- After have started off with a TBI 350, and offroaded with it....

I would GLADLY trade it for a 6.2. My 6.2 pickup, with the NV4500 makes me acutally consider having a stick shift for an offroad vehicle. (Prior to this, I have always felt that I did not want a manual, so I could be in better control. Just too many pedals for me.

With my pickup, I've got 6.31 first gear, with a 241 (2.72 ratio) 4.10 rear, and 30in tire. I have a final effective crawl ratio of 70.37:1, and some pretty good darn torque just at idle!

And while a diesel may be "smelly" , it really isnt any smellier than some badly tuned SBC and BBC's with really loud strait pipes as they rev up, without catalitic converters.