350 TBI tows 5000/6000lbs

[gmc406]

Guys he does not need new heads. simply bolting vortec heads on will do nothing. The swirlport heads are not as bad as people think. they flow enough air and have a generous amount of cross section. These heads work well in leancruise because you dont need to add 40 degrees of timing.

here are a few different builds i have done over the years for myself and customers.

208/216@.050 .460 lift 112 lsa made 240hp @4900rpm 360lbft@3500rpm stock intake. custom tune and headers. Then we swapped to performer intake with adapter. engine made 270hp@5100 340lbft@4000. this was just our shop truck.

218/218@.050 .465 lift 112lsa made 295@5200 350lb ft 4000 9.5:1 .030 basic valve job bowl blend. edelbrock performer headers and tune.

224/234@.050 .465/.485 112 made 310@5400 360lb ft 4000 9.5:1 .030 similar as above

all these engine were for guys that wanted nothing but improved power for towing. the best thing you can do is change your rear gears put a 2500 stall lock up in in and a big trans cooler. it will drive completely different.

As far as throwing a carb on it. DO NOT! I have tuned probably 50 of these engines using tunerpro and eblflash, also burning my own chips.

My advice is just stick a cam and springs in it, put in an external adjustable fuel pressure regulator and a different fuel pump. i used a bosche replacement for a grand national. Next would be torque converter. dont worry about people saying 2500 is too much on the street. thats bs you have lock up.

Bingo

[gmc406]

There are options out there. This setup is run off the TBI computer. It was worth some nice gains at the track when directly swapping out the stock intake. It even accepts EGR if emissions are an issue.

[donforeman]

Thanks for the advise. I have found two of those manifolds missing the rails and injectors for dirt cheap in the past few months. I asked on other forums and no one could provide much feedback so I passed.

[midnightbluS10]

Tbichips gained something like 50 hp from a vortec head and cam swap on their tbi truck. 140 to around 190.
190 isn't much buts it's a lot more than the 140 it had.

[donforeman]

Tbichips gained something like 50 hp from a vortec head and cam swap on their tbi truck. 140 to around 190.
190 isn't much buts it's a lot more than the 140 it had.

Yes, I am not expecting to double the rwhp but a little better while staying within a budget might work. I have been able to make small changes to the chip with help from the nice people at gearhead-efi forum. If you do a search of that forum "tbi chips" has a VERY bad reputation there, for doing shady things to his customers chips, but its a forum so who knows. They say though if you can learn to burn your own chips its much better so that's the plan. I have been doing it without much trouble, but changes are so much slower than working with a modern efi system like Holleys.

[Tuner]

Using the analog output from an Innovate MTX-L gauge or LC-2 or LM-2 (LM-2 is also a data recorder) to trick the stock ECU to run lean at cruise will give a substantial improvement in MPG.

This post is from 4 years ago.

Do not think of the swirl-port heads and “sensitive to timing” as if were a bad thing.

A Hudson Hornet combustion chamber is so efficient it only needs 17° total, some Flathead Ford cylinder heads only need 15° total.

The key word is “need”, as in, “that is all they need for best power and any more than that is bad because it makes less power, whether it knocks or not.”

The swirl-port head combination of intake port and combustion chamber is so efficient that ‘only’ 24° total is required to complete combustion at the desired crank angle for best power.

This is a good thing because less pressure before TDC is less negative work. Less combustion force is pushing the crankshaft backwards and more of the combustion force is applied to pushing the crank forward. The result is dramatically improved efficiency.

I recently installed an Innovate MTX-L to improve the mileage on a ’90 TBI 350. The MTX-L analog voltage output was set up to feedback the ECU O2 input with normal NB O2 voltage oscillation, which is .1V ~ 1V, but programmed to provide that voltage oscillation at 16.5 AFR.

So far, it is getting 17 MPG in mixed city street and freeway driving, and that is up from the 12 MPG it was getting with the stock O2 sensor. The plan is to try it a little richer and leaner than 16.5/1 to see if it can improve from there.

This ’90 TBI 350 has the swirl-port heads and stock hyd-roller cam. It is a used stock engine and TBI electronics package and the 700R4 and transfer case out of a ’90 Suburban in a 4WD Toyota Tacoma with 34” tires and (I think) 4.11 gears.

I like the swirl-port heads.

[gmc406]

Using the analog output from an Innovate MTX-L gauge or LC-2 or LM-2 (LM-2 is also a data recorder) to trick the stock ECU to run lean at cruise will give a substantial improvement in MPG.

This post is from 4 years ago.

Do not think of the swirl-port heads and “sensitive to timing” as if were a bad thing.

A Hudson Hornet combustion chamber is so efficient it only needs 17° total, some Flathead Ford cylinder heads only need 15° total.

The key word is “need”, as in, “that is all they need for best power and any more than that is bad because it makes less power, whether it knocks or not.”

The swirl-port head combination of intake port and combustion chamber is so efficient that ‘only’ 24° total is required to complete combustion at the desired crank angle for best power.

This is a good thing because less pressure before TDC is less negative work. Less combustion force is pushing the crankshaft backwards and more of the combustion force is applied to pushing the crank forward. The result is dramatically improved efficiency.

I recently installed an Innovate MTX-L to improve the mileage on a ’90 TBI 350. The MTX-L analog voltage output was set up to feedback the ECU O2 input with normal NB O2 voltage oscillation, which is .1V ~ 1V, but programmed to provide that voltage oscillation at 16.5 AFR.

So far, it is getting 17 MPG in mixed city street and freeway driving, and that is up from the 12 MPG it was getting with the stock O2 sensor. The plan is to try it a little richer and leaner than 16.5/1 to see if it can improve from there.

This ’90 TBI 350 has the swirl-port heads and stock hyd-roller cam. It is a used stock engine and TBI electronics package and the 700R4 and transfer case out of a ’90 Suburban in a 4WD Toyota Tacoma with 34” tires and (I think) 4.11 gears.

I like the swirl-port heads.

Maybe I’m wrong but a 90 TBI 350 never had a hydraulic roller. My 91 certainly didn’t.

[dfarr67]

Some came roller ready sans hardware.

[dfarr67]

There are options out there. This setup is run off the TBI computer. It was worth some nice gains at the track when directly swapping out the stock intake. It even accepts EGR if emissions are an issue.

I had this with vortec heads- great system, needs tuning- not the pos chip it came with. Saw NOS for cheap. If I had the EBL back then, I would still be running it.

[cardo0]

Not trying to flame anyone but from my experience towing a 3&1/2 ton trailer with a half ton you need a stronger platform. Towing my trailer cross country using my '90 SPORT 350 half ton cracked the 5sp trans case and destroyed the half ton rear end. Yes the half ton is not made for heavy towing and you do have a better rear end in your van. I considered upgrading rear end to 12 bolt along with air bags and stroker 383 but the trans would need some type of upgrade also making it all an experiment. Traded in for a new 12v Cummins dually and never looked back.

Yes I know buying new is not your option. But I've meet others towing with the 8.2l vortec and those should be available in trucks on the used market for reasonable prices since they are gas hogs. Just my suggestion.

[donforeman]

Thanks for the advice. This is my upgrade, ha ha. I had a super clean 96 f150 and that would not pull much of anything. The van chassis wise is much heavier than my 1/2 ton ford and it reminds me of that every time I hit a bump. I do see the point you are making and struggled with the idea of selling the van and trying again. So far though I am sticking with the van. The 4l60e was upgraded for towing already with Sonax Sunshell, additional clutches and the new Sonax heavy 3-4 plate kit and other parts. I did the work, I figured since it was me that's stuck on the road if the trans explodes, I may take a little more care in its assembly. Its still a weak link, but so far the fluid is still bright and no awful stuff in the pan. The rear diff has new bearings and the 4.11 gear. I dropped the tank and put in a big block TBI fuel pump so if I did work on the engine, the pressure can be raised with out pegging the pump. Like you said its all an experiment and something could fail at any time. If I sold it now though, I would probably see it driving trouble free for years while I repaired my new project, I have been there a few times! I am still open to the possibility of stronger vehicle, and check the ads a few times a week.

[Truckedup]

Not trying to flame anyone but from my experience towing a 3&1/2 ton trailer with a half ton you need a stronger platform. Towing my trailer cross country using my '90 SPORT 350 half ton cracked the 5sp trans case and destroyed the half ton rear end. Yes the half ton is not made for heavy towing and you do have a better rear end in your van. I considered upgrading rear end to 12 bolt along with air bags and stroker 383 but the trans would need some type of upgrade also making it all an experiment. Traded in for a new 12v Cummins dually and never looked back.

Yes I know buying new is not your option. But I've meet others towing with the 8.2l vortec and those should be available in trucks on the used market for reasonable prices since they are gas hogs. Just my suggestion.

What is the towing weight limit for the truck you mentioned? Would it be about 2000 pounds less than you were towing?

[cjperformance]

I did a budget job for a mate a couple years ago, he had a toyota hilux ex-diesel 5spd 4wd with a 307 chev in it. It towed his boat and did some light off road work. Not a racer but was not great towing at 100kph He got hold of a $1500 (australian) 383 short on ebay. I had a set of heads and a cam from a 290hp gm crate engine i had cam and head swapped for another project. We used the heads and cam on the 383 short, his 307 had a stock spreadbore intake and a 465 holley. He bought a performer intake and we reused the 465. It was a fantastic tow engine , all grunt from idle on and about 4500 was the most rpm it ever saw. Areas of road where it would need 3rd to pull the boat it did easily in 5th still. Pretty cheap basic smooth and it worked.
I dont know about the tbi unit/ecu but others would know if it would work on a 383

[Schurkey]

For the record:
The Caprice 5.7L TBI had flat-top pistons instead of the Pickup/Van dish pistons. Advertised as good for a slight compression bump from ~9.2 (truck) to about 9.5 (Caprice). The Caprice pistons are available in the aftermarket, and they're VERY inexpensive. 2.0, 1.5 4.0 metric ring pack. They're a little short on compression height at 1.550.
https://www.summitracing.com/parts/slp-h597dcp

Summit sells aluminum swirl-port replacement heads that retain the heat riser passage, (and therefore EGR), and the goofy intake bolt pattern where the two middle bolts go in at an angle other than 90 degrees to the gasket surface. Don't get caught using self-aligning TBI rocker arms with pushrod guideplates--and the OEM TBI pushrods are not hardened.
https://www.summitracing.com/parts/sum-162108

I've heard that the TBI stock intake manifold is very poor, with uneven fuel distribution. I have not confirmed that.

[gmc406]

Reread your original post. If you’re down to 40 mph while towing, I’m not so sure a 350 with bolt ons will get you to where you need to be. I’m thinking you may be in 383 territory, or better yet.... big block. Sounds like you need a good 100+ ft/lbs of torque.

JMHO.