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L29 Vortec 454 on a budget

General engine tech -- Drag Racing to Circle Track

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travis
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L29 Vortec 454 on a budget

Post by travis »

What can you do with one of these things for under, say, $2000?

My '99 Suburban C2500 just isn't cutting it. It has a stock L31 350 vortec, 4L80, and 3.73's. At 5700 pounds empty there just isn't enough motor there for towing much of anything. I'm seriously considering purchasing a L29 equipped pickup and swapping engines, as I have found a few decently priced without a million miles on them. Do these things respond to basic things like a cam and headers while retaining the stock FI setup? Or is it the same situation as the L31, where the FI is pretty close to maxed out on a stock motor?

I'm in the midst of moving to another county that does not do smog checks, so going to a carb isn't out of the question, but that really feels like going the wrong direction for trying to keep some semblance of highway fuel economy and max low end grunt
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Re: L29 Vortec 454 on a budget

Post by prairiehotrodder »

sounds like a ton of work for little reward. I'd tweek your 350 a little and live with it OR sell the suburban and get something different. The vortec 350 can be a great motor but if its wore out it will be weak. This is what i would do with it if i wanted to wake it up:

rebuild it with flat top pistons .020 over
the right cam
deck the block
new timing chain
shorty headers with nice mufflers and exhaust system
then look into what you can do with the computer (maybe do this first before you touch the motor)
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Re: L29 Vortec 454 on a budget

Post by Dragsinger »

Travis, up front I apologize for being off topic. Yet, if you ever tow with a diesel, the difference is simply fantastic.

Otherwise, I agree with the above post, way too much work and expense for a small gain.
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Re: L29 Vortec 454 on a budget

Post by pdq67 »

Hi Travis,

I always figured that to do a 350 this way, I would use an old 4-barrel, SP-2P intake and matching Q-Jet carb., along with small tube, 4-tube, long tube headers AND then pick a, "grunt" cam like one of the Crower Beast's.

But get your CR up into the 9's and use thin head gaskets. Sure, it will be dead above say 4,000 rpm, but it should be a grunt monster up to it's short top-end!

I really don't think that you will be happy using your EFI only because it isn't, " really", designed to make good power is all, but try it if you want to. Might look into the, "Compu-Cams", to try to find one compatible here? Heck, there may be a chance the old, "Performer", 204/214 cam might work?? And don't forget that no more than the great old, stock, -929 cam is great if you get your engine's CR up there. I figure that the -929 cam is the most versatile cam ever made!

Now, the L-29 engine. It's heads are true small intake port large ovals at right around 230 cc's or so! This said, the chambers are 100 cc's and a modern, "heart-shape".

Get one's CR again up into the 9's and go. Now see if you want to run a carb. or an EFI? Add small tube, (1.75" dia.), headers and such too. Cam should also be a grunt cam but picked for either EFI or a carb. system like you already know about...

Heck, buy an old farm truck 454 engine and add a pair of old -206, 96.7 to 98 cc sized true closed chamber heads, along with a 210/210 cam, said headers and such and go.

Hope this helps?

pdq67
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Re: L29 Vortec 454 on a budget

Post by F-BIRD'88 »

One of the resons why your lil 350L31 does not seem to have enough oats
to tow well is the truck does not have enough rear gear in it.
especially X if it now has non stock tires that are taller than stock.
This cuts down he gear even more. You need gears (torque multiplication) to pull a heavy load with a heavy truck and and (relative) small motor
Change the gears from 3.73 to 4.30 ...4.56.

The OD trans 4th gear ratio really tames down the 4.56 gears ( for when not towing) to make it all livable.

2. I would build another motor as a 383 SBC. These motors make a LOT MORE Torque. Use the roller cam from the GMPP 350 RAMJET motor.
It is short duration yet high lift and increase power.
That whole ram style RAMJET induction system is a winner too.
Another EFI induction system you can consider is the 80's GM TPI EFI
The EFI allows you to use a NON vortec head for your HAULING 383
if you want.

You could get a whole complete 350L98 TPI motor and rebuid it and hot rod it
as a 383. Full port the "083" heads, higher lift hyd roller cam, headers ex
etc. This hot rodded 383 TPI motor will also make a TON of low mid torque
and more HP than the L31 vortec 350.
Lots of options on that high torque 383. Can use the vortec heads. can use a non vortec head. Some people have used the Marine 350 "Black Scorpion" Vortec (tunnel Ram style EFI system on their hot rodded 350-383 truck motor.
this is the EFI induction from the Mercruiser Black Scorpion 5.7 350 vortec ski boat motor.
It makes a ton of torque right where you need it and even more on a 383CID motor. It all fits under the truck hood too.

AGAIN swap the gears in the truck for higher ratio rear gears for more TOWing
grunt. X2 if tires are now taller than stock.
You can exceed the power of the BBC motor with a hot rodded 383.
If you raise the compression ratio you will need good 92 octane gas when towing.
Just don't get carried away with that or the HYD roller camshaft. Keep the duration short but tweek the lift and LSA to work with the new induction and exhaust headers. it will still have good fuel mileage.

The vortec Holley "Stealth RAM" EFI induction is another option.
Again way more torque and power than the OEM L31 induction system
ESpecially on a 383 version with ported vortec heads....or other.
Keep the cam small and it will work great for towing.
The tuned runners are longer and straighter and just the right size
to make big mid range torque and power.

This is the Black Scorpion EFI (vortec)
http://i1202.photobucket.com/albums/bb3 ... rupper.jpg

Edelbrock should have jumped on this when they were making the intakes for Mercruiser.
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Re: L29 Vortec 454 on a budget

Post by F-BIRD'88 »

If when you change the rear axle gears in your truck you will now be able to tow
in OD (on flat level road at steady even speed) DO NOT try to accelerate while in OD
gear. It is a "cruising gear" Drop down to "D" for passing, acceleration and hills while towing a lead.
You will have much more Grunt TORQUE and the OD gear will be much more useful
when towing. (On level ground only)
If you were to look at a dyno graph printout of event the stock L31 motor
you'd see where the engine makes all its TORQUE and what engine rpm range you want to be at.

Are your truck tires taller than stock?

By changing the gears, from 3.73 to a 4.30:1 gear even the stock L31 motor will feel and pull like it is a 400CID motor. A 383 will feel and pull like it is a 440CID motor.
A 15% Increase in towing pulling TORQUE in all gears.
This assumes the tires are Stock OEM height. If they are now taller than OEM use a taller gear as required EG: 4.56 ish)
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Re: L29 Vortec 454 on a budget

Post by F-BIRD'88 »

Re: Towing and fuel consumption.
If when you make the motor more powerful to pull the load QUICKER and or FASTER either or both Quicker towing acceleration or faster towing Speed
You will BURN MORE Fuel to get that.
If you want to tow quicker and or faster expect to BURN MORE Total FUEL on that trip. If you make extra power and use it, while towing, you will BURN MORE FUEL.
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Re: L29 Vortec 454 on a budget

Post by Keith Morganstein »

A stock l29 will wake that burb up.

They respond to a cam change
PCM swap and tune, aftermarket inj, or manifold and carb.

Go for it.


travis wrote:What can you do with one of these things for under, say, $2000?

My '99 Suburban C2500 just isn't cutting it. It has a stock L31 350 vortec, 4L80, and 3.73's. At 5700 pounds empty there just isn't enough motor there for towing much of anything. I'm seriously considering purchasing a L29 equipped pickup and swapping engines, as I have found a few decently priced without a million miles on them. Do these things respond to basic things like a cam and headers while retaining the stock FI setup? Or is it the same situation as the L31, where the FI is pretty close to maxed out on a stock motor?
Automotive Machining, cylinder head rebuilding, engine building. Can't seem to quit #-o
travis
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Re: L29 Vortec 454 on a budget

Post by travis »

A diesel would be awesome, but my only real option there is an Excursion...I have 5 kids so seating is an issue. Besides, I've driven a couple of Excursions...I don't think I want one. I've also driven a few of the 6.5TD suburbans...they feel only slightly less gutless than the 6.2 non-turbo burb I owned a few years ago. The 21mpg highway mileage was nice, but a 4000 pound camper behind it netted a top speed of 58mph...

I have been thinking hard on the 4.56 gears. My tires are only slightly taller than stock (like 1") but with all my money going into this new house, my "upgrade" budget is really small right now. Gears, and maybe one of them Hypertech tuner thingamajigs (they claim like +45 torque and +20 hp) may make it liveable for under $1000. Maybe even a set of roller rockers too.

Mechanically the engine is sound, it would just work better in something about 2000 pounds lighter
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Re: L29 Vortec 454 on a budget

Post by F-BIRD'88 »

You also have the option of changing the effective gear ratio by changing the tires
diameter. Changing the tires from say 33" diameter to a set of 28" diameter tires
on the truck is the same as if changing the gears from 3.73:1 to 4.30:1.
The 15% change in gearing torque multiplication is the same same.

If your current tall tires have a aggressive off road 4x4 style tread
and you change that to a more hi-way friendly running tread you may well even pick up some mileage . The off road tread 4x4 truck tires that look beastly really suck up vehicle power and fuel. This off road style of tire tread works against you for street and hiway driving and towing.

Tires make a big difference. What size are the tires (sidewall size) P275-70R-15 ??
What is the measured effective (loaded) rolling diameter (radius x 2) as measured from the ground to the center of the axle.

You'd want a new tire that is 15% shorter diameter yet can still have the required load rating, including the tongue weight of the trailer, when towing.
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Re: L29 Vortec 454 on a budget

Post by F-BIRD'88 »

On gasoline engines those aftermarket tuning chips or controllers
only really show such power and torque gains if when combined with engine induction/exhaust AIRFLOW improvements.
If when the "chip" makes the EFI spark timing more aggressive plan on needing to use a higher octane fuel, (especially for towing).
You will lunch that engine quick if it is knocking under load because the fuel octane is not now enough with modified aggressive EFI system spark timing. it ain't going happen on cheap 87 octane gas.
Remember making and using more engine power and torque will burn more fuel.
That makes towing more expensive.
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Re: L29 Vortec 454 on a budget

Post by Carnut1 »

https://www.speed-talk.com/forum/viewtopic.p ... ck#p564816 Take a look at this old thread of mine. 2009 buick enclave. Quick mods to intake plastics, airbox, throttlebody. Added K+n filter. Woke it up enough that I haven't needed to do any more and it is livable. Never blew a code from these mods. Mpg went up a tad. Cost of filter only. Did the same mods to my 2001 astro van and made a good difference as well. Thanks, Charlie
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Re: L29 Vortec 454 on a budget

Post by rfoll »

You could stroke the L31 to 383. With a little more tuning it might be enough. If you go away from the efi, a 400 small block with your Vortec heads could be done. My neighbor has a 99 3500 with the 454, and he thinks it's a gutless fuel hog.
So much to do, so little time...
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Re: L29 Vortec 454 on a budget

Post by 77cruiser »

Wonder what would be involved swapping in a DMax? How much for a good runner used?
Jim
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Re: L29 Vortec 454 on a budget

Post by travis »

Duramaxs are gold around here...way more work and expense than I want to deal with.

Stock tire size was 245/75-16...I have 265/75-16 Yokohama Geolanders...kind of a mild all terrain type tire. A 26" tire would be needed to make it equivalent to a 4.56 gear. This would be like the guy that has huge pecs and arms...and chicken legs :D It would look completely wrong...besides, I seriously doubt you would find a E1 load range tire in that size.

A gear swap would be cheaper than changing all the tires anyway

It would be really easy to duplicate the HT383E for much less $$$ than what GM charges for one...
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