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Straight sixes and fuel economy

I saw a 250 in a nova several years ago with a side-mounted roots-type blower running 9s in the 1/4-mile. I think he had weber side-draft carbs on it. My old '65 longbed got 15-16mpg highway w/ a 3-speed stick and a 292, but I was revving the piss out of it going back and forth to work. There used to be an aluminum crossflow head avail. I met the guy who made them in the early 90's, but he wasn't exactly young then. He had a few drag cars with 292s. One was a rail with 2 292' connected end to end. It was crazy fast.
 
throttleissues said:
There used to be an aluminum crossflow head avail. I met the guy who made them in the early 90's, but he wasn't exactly young then. He had a few drag cars with 292s. One was a rail with 2 292' connected end to end. It was crazy fast.
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Sounds like you met Mike Kirby or Kay Sissell. I'm not sure when Kay passed away. Sissell Automotive is still in business with Kirby at the helm.

Sissell makes a pretty sweet aluminum head for the sixes, but it's not crossflow (intake and exhaust are on the same side). It's pricey, (over $3k) but damn nice, and Weber DCOE's (side draughts) will work on it.

throttleissues said:
My old '65 longbed got 15-16mpg highway w/ a 3-speed stick and a 292, but I was revving the piss out of it going back and forth to work.
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I'm still wondering what a 292 willl do, fuel economy-wise, with an OD tranny. Especially if it were re-cammed to rev a little higher.
 
Ok so a few have talked about the 4.3 but has anyone actually tried putting one into one of these heavy trucks? I have a two year old 4.3 rebuild, that is making 200 horses with TBI (according to the engine builder), and in the Astro it would get up and go no doubt about it. But let's face it, the Astro weighs 1200 lbs less than my 80 K5. I would love to drop that thing into my K5 just for fuel economy, and because the trans is toast in the Astro, but where am I going to get motor mounts?
 
A 4.3 has the same mounts as a 350. I would do it with a manual to get the most out of the v6. In the past some have said you'll wear it out faster in a heavy k5, But I'm sure it will last awhile if you don't dog it. The 200hp version, I think, has about 260lb of torque in stock form.
 
Ok so a few have talked about the 4.3 but has anyone actually tried putting one into one of these heavy trucks?
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sort of. my c1500 xcab is very close in weight to my k5 and the v6 pulls it around very competently. every day, i cruise at about 85mph on the way to work, and it can do much more...just not sure how much, since the speedo tops out at 85. i was pulled over for 107 in a 70, one time. when i'm hauling stuff, the truck doesn't seem to care, and i've towed more than 8000lbs at 70mph before. it's a pretty big v6, but it thinks it's a medium-sized v8 :wink1:.

i almost forgot to mention that my pickup has a little better aerodynamics than the blazer. that helps, some.
 
bear76 said:
A 4.3 has the same mounts as a 350. I would do it with a manual to get the most out of the v6. In the past some have said you'll wear it out faster in a heavy k5, But I'm sure it will last awhile if you don't dog it. The 200hp version, I think, has about 260lb of torque in stock form.
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Well yes and no, we were comparing them at the Napa store today. They are close to the same mounts, but the 4.3 mounts are a little further back than the 350 mounts so there may be some custom engine side mounts to be fabbed. I am thinking power wise there shouldn't be much difference between my 4.3 and a stock 350, maybe a bit more power from the 4.3, but a lot more room under the hood.
 
I have a friend with a "trazer" and he has had a 292 in it since the original blazer was a few months old. Something about his dad blew up the 305 and had gm dealer put the 292 in blah blah blah. Anyway he has done all kinds of stuff to that old six. About 3 years ago he built a intake that sorta looked like a header and arched over the valve cover, topped by a 650 holly. That didt work so well and he tried some sort of tri-power set up rebuilt the engine with some sort of heavy truck cam and it worked but sucked gas. Last year he rebuilt it again and went with LPG and a matching cam, but left the pistons at stock ratio.

Last I talked to him he was going BACK to the heavy truck cam, higher compression, and modifying a FI system off a 3 cyl car of some sort with another home made intake. Lighten the truck as much as he could and go to d44 axles front and rear replacing the d60 14b he had and going to a np208 over the heavier 205. I think hes going to stay with the sm465. He even thought about useing my chevy luv step-side fenders on light bedsides but they where too small.

He wrenches more than he wheels it seams and hes always trying to modify that 292. I rode in the truck when it was still a blazer and rollin 35's and the header-intake/holly650 thing. It did very well in low range other than he had alot of slosh/flood and vibration(cracked his intake) problems.

I dont get to talk to him much because he lives on a cattle ranch out in the sticks. Not to mention he has a very wierd personality. He isnt very educated but I used to take him all sorts of automotive books, and hes a self taught(maybe his dad helped) mechanic.

As far as feul economy I couldnt tell you, but he seamed to realy like the heavy truck cam. Maybe higher compression the truck cam and LPG would do well. You kinda got me thinking and I may have to make a trip to visit him and see how its coming along.

Sorry this post isnt very info based I just thought Id share.

Balzer
 
lectric80 said:
Well yes and no, we were comparing them at the Napa store today. They are close to the same mounts, but the 4.3 mounts are a little further back than the 350 mounts so there may be some custom engine side mounts to be fabbed. I am thinking power wise there shouldn't be much difference between my 4.3 and a stock 350, maybe a bit more power from the 4.3, but a lot more room under the hood.
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A V6 swap into a K5 would be interesting. I suppose it success (or perception thereof) would be determined by what you were using it for. I see guys in the mags all the time running 44's being driven by a 4cyl, so with enough gearing you *should* be able to pull anything. I wonder how it'd be out on the street though...
 
original balzer said:
I have a friend with a "trazer" and he has had a 292 in it since the original blazer was a few months old. Something about his dad blew up the 305 and had gm dealer put the 292 in blah blah blah. Anyway he has done all kinds of stuff to that old six. About 3 years ago he built a intake that sorta looked like a header and arched over the valve cover, topped by a 650 holly. That didt work so well and he tried some sort of tri-power set up rebuilt the engine with some sort of heavy truck cam and it worked but sucked gas. Last year he rebuilt it again and went with LPG and a matching cam, but left the pistons at stock ratio.

Last I talked to him he was going BACK to the heavy truck cam, higher compression, and modifying a FI system off a 3 cyl car of some sort with another home made intake. Lighten the truck as much as he could and go to d44 axles front and rear replacing the d60 14b he had and going to a np208 over the heavier 205. I think hes going to stay with the sm465. He even thought about useing my chevy luv step-side fenders on light bedsides but they where too small.

He wrenches more than he wheels it seams and hes always trying to modify that 292. I rode in the truck when it was still a blazer and rollin 35's and the header-intake/holly650 thing. It did very well in low range other than he had alot of slosh/flood and vibration(cracked his intake) problems.

I dont get to talk to him much because he lives on a cattle ranch out in the sticks. Not to mention he has a very wierd personality. He isnt very educated but I used to take him all sorts of automotive books, and hes a self taught(maybe his dad helped) mechanic.

As far as feul economy I couldnt tell you, but he seamed to realy like the heavy truck cam. Maybe higher compression the truck cam and LPG would do well. You kinda got me thinking and I may have to make a trip to visit him and see how its coming along.

Sorry this post isnt very info based I just thought Id share.

Balzer
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I had to laugh at parts of this. Especially the manifold that came over the head. That was good.
 
jonrpick said:
I had to laugh at parts of this. Especially the manifold that came over the head. That was good.
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I can only assume he was trying to keep the heat of the exhaust away from the carb. Or maybe improve the intake runners? :confused: :dunno:

Balzer
 
original balzer said:
I can only assume he was trying to keep the heat of the exhaust away from the carb. Or maybe improve the intake runners? :confused: :dunno:

Balzer
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I actually found yet another aftermarket 12-port 292 head today. It's real limited in production, apparently the folks that originally sold it stopped making them and sold the molds to someone else who does make them to order. No website unfortunately :crazy:

But here's a pic of the thing:

detail


1152937731_9e37b78115.jpg



The company, Duggan, also made the block. It's an all-aluminum 292!!!!

The guy who owns it is selling a 292 turbo-ready exhaust manifold on eBay, seen here:

http://cgi.ebay.com/ebaymotors/ws/e...STRK:MEWA:IT&viewitem=&item=280142817518&rd=1

That motor has a stock head with the "lump ports" added and a turbo installed. He says he still has his low-end torque and that it pulls all the way to 5000rpm and makes around 500hp.

Long live the 6!

detail
 
jonrpick said:
I actually found yet another aftermarket 12-port 292 head today. It's real limited in production, apparently the folks that originally sold it stopped making them and sold the molds to someone else who does make them to order. No website unfortunately :crazy:

But here's a pic of the thing:

The company, Duggan, also made the block. It's an all-aluminum 292!!!!

The guy who owns it is selling a 292 turbo-ready exhaust manifold on eBay, seen here:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=018&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=280142817518&rd=1

That motor has a stock head with the "lump ports" added and a turbo installed. He says he still has his low-end torque and that it pulls all the way to 5000rpm and makes around 500hp.

Long live the 6!

detail
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Also... you can see his motor in the eBay auction. He machined the manifold for MPFI. He's using 2 injectors per port--or one per cylinder. He did this instead of futzing with a 3 injector setup. Even though they share the same port, he says it works great.
 
Spending that much money on a six just seems silly to me. The extra money you save by building a V8 could easily pay for 20k-30k of fuel.

If you just did a stockish rebuild with a ported head and a cam I could see that. But to each his own.
 
ryan22re said:
Spending that much money on a six just seems silly to me. The extra money you save by building a V8 could easily pay for 20k-30k of fuel.

If you just did a stockish rebuild with a ported head and a cam I could see that. But to each his own.
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Spending what kind of money? I'm certainly not dropping $3-5k on a head! But I'm not opposed to buying a reworked stock head (seen 'em for a few hundred on eBay) and the turbo stuff though.

The whole point of going with a six is that they are unique, and they can be built to put out some serious power. Regardless of whether you're building a six or V8, you can spend as much as you want and never outperform someone who's carefully selected their parts. As you say, a ported head, cam, and also intake/carb setup will go a long way to improve a six.

Dropping the big bucks like that is for the guy that's trying to shave that extra 1/2 a second off their 1/4 mile track times.
 
jonrpick said:
Spending what kind of money? I'm certainly not dropping $3-5k on a head! But I'm not opposed to buying a reworked stock head (seen 'em for a few hundred on eBay) and the turbo stuff though.

The whole point of going with a six is that they are unique, and they can be built to put out some serious power. Regardless of whether you're building a six or V8, you can spend as much as you want and never outperform someone who's carefully selected their parts. As you say, a ported head, cam, and also intake/carb setup will go a long way to improve a six.

Dropping the big bucks like that is for the guy that's trying to shave that extra 1/2 a second off their 1/4 mile track times.
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I would like to mention, the Vortec 4200 inline 6 that GM is using in the Trailblazer and similar looks to be a pretty great engine. I've seen low-mileage examples going for reasonable prices when they've been pulled from a wreck.

It doesn't have quite the displacement of the 292, but the stroke is right at 4 inches and for the size of the engine, the dyno chart looks fairly good.
 
The one in my wife's trailblazer does just fine. They are rated for 270-290 hp depending on year, but it's at 6000 rpm. Mine never goes above 4500-5000 even in a 30-70 traffic merge. The only problem with them is that no one makes a tuner for the ecu. I'd imagine that it would be a pain to get the thing to run with the anti theft and emissions and whatnot. The makers of LS1/LT1 edit claim ( I sent them an email asking if they could support the 4200's ECU) that in 08 or 09 their software will be able to tune the computer, which would then make it a viable option.

They are very lightweight, and have a superior engine design. Just stay away from the early production engines (99 models). They had a problem with machining and the #5 cylinder liner would become dislodged and destroy the engine.

I wasn't sure if you were going for the aluminium head or not. But I definately see the build that you proposed working just fine.
 
I have built a number of inline six bangers. I have done performance builds on Chevy 250s and Ford 300. I could never get one to get much better gas mileage than a good running chevy 350
The last six i built was in my 85 ford Bronco The more performance stuff I added the MPG went down. It went from 17MPG stock to 15 MPG after 390 CFM 4 barrel carb, mild cam,4 bbl intake manifold, headers,mild porting on the heads, ignition, ECt. It ran great with plenty of power. But not too good in the MPG department.
Even the new 4.2 L I6s in the TrailBlazers dont do better than 18 MPG highway. Average MPG for them is around 14 MPG. The 5.3 V8 models get around 16 MPG very slightly less MPG than the 4.2 6
IMHO good gas milage and inline sixes dont mix. If you are looking for better gas milage build a V6 or better yet build a 350 with fuel economy in mind.
I get 18 MPG highway 14- 15 average in my old 89 TBI K5 with a 350 V8
 
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