Boosted 350 vortec, or stock 8.1?

[skylark]

6.0 LS or a 5.9 Cummins. There is a huge aftermarket for both platforms so you can get parts just about anywhere. Definitely not the case with a 8.1. The boosted 5.7 wouldn't be a bad option but for all of the money that you'd be paying out to get the supercharger and the intake/injectors up to par, you could be money and fuel efficiency ahead with the 6.0 or 5.9.

 

[Christian Steffen]

Back when I was 1st out of highschool, I was a carney. The vehicle that I drove from fair to fair was a square body 3+3 dually with a 454, pulling a 5th wheel camper. We changed cam and did a few mods. The 454 did ok, but always felt sluggish, and usually got 4-6 mpg. I have driven a couple vortec 454's and while better, the 8'1's that I have driven seem to be in a different league. May be just how they feel though.

The low compression ratio that thing had did it no favors. Stock vs stock the 8.1 is always going to beat the 7.4, if price and availability are similar i'd probably pick the 8.1 unless you think you're going to do more than maybe a cam swap.

A cummins swap would probably be the ultimate pulling setup, but that is going to be more work than an 8.1 swap.

I realize the aftermarket is huge for the 6.0, and they're good engines, but I really don't think it's going to compare to the 8.1 for towing. All other driving duties I'm sure it would work well though.

 

[BNielsen]

Why not build a 496 out of a 454?

Or you could go the extreme route and swap in a Duramax? 6.6/ZF6 in and ECSB K2500, anyone else think that rings a bell?

 

[Supercharged111]

Supposedly a gen VI cam fits and 8.1, so that and headers with tune and you're pretty much done with towing mods. I tow with an 8500ish pound trailer boosted 350 and it's enthusiastic. My dually seems less enthusiastic, but then I add the 5000# slide in camper and the truck tolerates that too so I will say that the big block reacts differently than the boosted 350 does to weight. It's weird. 350 will blow the doors off my 454 as they sit right now empty.

 

[John Cunningham]

The 8.1 will probably last longer doing a lot of towing, might get better mileage while pulling hard too. 8.1 will probably be more reliable? Not sure which would make more torque at low rpm? 350 would probably get better mileage unloaded.

I am building a 496 that will be blueprinted to the max. I will even be using low drag rings and roller rockers and things that I can get some free horsepower without missing the point. I am using the new style Vortec head with a 3 angle competition valve job concentrating on low lift flow, a cam well chosen with the right LSA. This will be a negative overlap cam and compression around 9:1
It will be a simple 496 cubic engine and will still use the stock Vortec manifold with LS1 control. I dynoed my 454 and it was horrible with the stock black box. I know from what I saw I can double my torque and reduce the rpms at towing speeds of 2500 rpm.. I am going from a 4:10 back to a 3:73 and tow using all the torque I can get. I will dyno it first and the gear would be the last thing I would change. A gear vendors would be the ultimate with the right rear gear. I feel I can make 550 ft pounds of torque around 2500 to 2800 rpm. That is almost early year (2004-06) duramax torque but a little higher rpm. No small block will ever tough this and the nice thing you dont need headers at this low rpm...they would maybe get you a couple of HP but thats it......not worth the hassle.

 

[L31MaxExpress]

Properly sized headers actually make a nice difference on the bottem end as well. The Thorley Tri-Ys I put on my Express van made a noticeable difference even way down at 1,500-2,500 rpm. So much of a torque difference that running 60-70 mph (1,800-2,200 rpn in 4th gear) it would hold overdrive on the same hills that previously caused it to kick down to 3rd. My stock 4L85E converter stalled 200 rpm higher after the headers. Brake stall increased from 2,200 to 2,400 rpm.

I also put Thorley Tri-Ys and TPI on the 305 in my old G20 van years ago. It had 3.08 gears and a 700r4 in it. It would climb decent sized grades at 70 mph @ 1,700 rpm in overdrive. With the dual plane intake, QJet and stock manifolds forget about it, it would downshift to 3rd and hang in 3rd the whole way up even the slightest grade!

I have had a hand in setting up some low speed engines for things like generators and water pumping. The manifolds can cost you 30-50 ft/lbs of torque compared to a decent header even down at 2,500 rpm.

 

[L31MaxExpress]

Time and time again headers have been proven to add a substantial boost to low-midrange torque on even stock engines. On a Goodwrench GM 350 70s smog engine a set of 1 5/8" long tubes added 53 ft/lbs @ 3,400 rpm and with both the headers and an edelbrock performer intake 59 ft/lbs gain at 3,400 rpm.

 

[Supercharged111]

I am building a 496 that will be blueprinted to the max. I will even be using low drag rings and roller rockers and things that I can get some free horsepower without missing the point. I am using the new style Vortec head with a 3 angle competition valve job concentrating on low lift flow, a cam well chosen with the right LSA. This will be a negative overlap cam and compression around 9:1
It will be a simple 496 cubic engine and will still use the stock Vortec manifold with LS1 control. I dynoed my 454 and it was horrible with the stock black box. I know from what I saw I can double my torque and reduce the rpms at towing speeds of 2500 rpm.. I am going from a 4:10 back to a 3:73 and tow using all the torque I can get. I will dyno it first and the gear would be the last thing I would change. A gear vendors would be the ultimate with the right rear gear. I feel I can make 550 ft pounds of torque around 2500 to 2800 rpm. That is almost early year (2004-06) duramax torque but a little higher rpm. No small block will ever tough this and the nice thing you dont need headers at this low rpm...they would maybe get you a couple of HP but thats it......not worth the hassle.

Gonna disagree strongly with you on the header comment. I typically observe gains from an idle to redline. Who in their right mind would drop the money to blueprint a motor and choke it down with stock manifolds? You'd be better off with headers and a non-blueprinted motor. Probably be dollars ahead too.

 

[John Cunningham]

Gonna disagree strongly with you on the header comment. I typically observe gains from an idle to redline. Who in their right mind would drop the money to blueprint a motor and choke it down with stock manifolds? You'd be better off with headers and a non-blueprinted motor. Probably be dollars ahead too.

Thats whats so great about America you have the right to disagree. I have spent hundreds of hours on engine dynos all the way back to the early 80's Have several NHRA records and was on the cover of Hot Rod Magazine in 2005. I know for a fact a header does not do hardly anything at 2500rpm to 3000 rpm. I only mention these things because I have been around awhile. Even if headers would work they need primary tubes to be extreme in length 36"38" which you cannot buy and very small in diameter 1 3/4 with a very small collector 2 1/2 in dia and bout 18 inches or longer in length. That's a custom hand built header at a cost of around $3000.00 dollars or more and I doubt you could find anybody to even want to build them for that. Any knowledgeable header guru would agree with this. Headers By Ed, Jack Davis Headers/Belanger headers.......These are the leaders in header tech. I own at least 5 NHRA records and in our day we ran 2 & 3 step headers before anybody even heard of them. I doubt you would even be familiar with any of this.........Mass produced shorty or store bought headers are worthless below 3000 RPM period. Now add to that fact that anything you can buy in a box are all junk. The flanges crack .pipes at welds crack and the bolts come loose, ignition wires are an issue and they wont last to long besides the ring and ting your going to hear as the torque of the engine is hummig. Pulling a trailer all day long will be a maintenance nightmare with the cooling and heating that happens. Your going to have issues and who wants to chase the problems. You wont see a 1/3 mpg increase.
Too finish this rebuttal to a guy who knows not to much.. every drag racer in the 70"s tried cams/headers/carbs/intake manifolds etc. Some of the best minds in engine building like Rehr Morrison etc tried everything. We pulled 40ft gooseneck trailers with 454 chevy duallys.....stock they got 6MPG and with thousands of dollars poured into research we all still got 6 MPG no matter what we did.
Most who had headers went back to Cast Iron manifolds and took the PIA headers off and got some peace and quiet as we got white line fever. It takes years of experience to learn these things and when we were all young the first thing we would say is lets put some headers on our trucks and after some experience with the headaches and non performance....they all came off. I have been building engines for 50 years and that has taught me some valuable lessons.

 

[L31MaxExpress]

Thats whats so great about America you have the right to disagree. I have spent hundreds of hours on engine dynos all the way back to the early 80's Have several NHRA records and was on the cover of Hot Rod Magazine in 2005. I know for a fact a header does not do hardly anything at 2500rpm to 3000 rpm. I only mention these things because I have been around awhile. Even if headers would work they need primary tubes to be extreme in length 36"38" which you cannot buy and very small in diameter 1 3/4 with a very small collector 2 1/2 in dia and bout 18 inches or longer in length. That's a custom hand built header at a cost of around $3000.00 dollars or more and I doubt you could find anybody to even want to build them for that. Any knowledgeable header guru would agree with this. Headers By Ed, Jack Davis Headers/Belanger headers.......These are the leaders in header tech. I own at least 5 NHRA records and in our day we ran 2 & 3 step headers before anybody even heard of them. I doubt you would even be familiar with any of this.........Mass produced shorty or store bought headers are worthless below 3000 RPM period. Now add to that fact that anything you can buy in a box are all junk. The flanges crack .pipes at welds crack and the bolts come loose, ignition wires are an issue and they wont last to long besides the ring and ting your going to hear as the torque of the engine is hummig. Pulling a trailer all day long will be a maintenance nightmare with the cooling and heating that happens. Your going to have issues and who wants to chase the problems. You wont see a 1/3 mpg increase.
Too finish this rebuttal to a guy who knows not to much.. every drag racer in the 70"s tried cams/headers/carbs/intake manifolds etc. Some of the best minds in engine building like Rehr Morrison etc tried everything. We pulled 40ft gooseneck trailers with 454 chevy duallys.....stock they got 6MPG and with thousands of dollars poured into research we all still got 6 MPG no matter what we did.
Most who had headers went back to Cast Iron manifolds and took the PIA headers off and got some peace and quiet as we got white line fever. It takes years of experience to learn these things and when we were all young the first thing we would say is lets put some headers on our trucks and after some experience with the headaches and non performance....they all came off. I have been building engines for 50 years and that has taught me some valuable lessons.

I have had 2 sets of out of the box tri-ys and have had NONE of the issues you mentioned minus one plug wire boot getting torched. I installed the 90* aluminum heat shields GM makes for the LT1s and never had another issue. They do get hot but so did the manifolds and both manifolds on my 5.7 Express van cracked in under 70K miles. I have also never noticed the ticking you mention from them. Heavy gauge pipes that are coated and the Thorleys have 1/2" flanges. With the proper length of bolt I never have had an issue with them loosening either. To each their own. The Tri-Ys made a very noticeable difference dragging around my Express van and travel trailer. The XFI roller cam was far more noticeable sound wise than the headers.