Suggestions for 150k refresh for more power? - S-10 Forum
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post #1 of 16 Old 06-22-2019, 05:54 PM Thread Starter
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Suggestions for 150k refresh for more power?

Would anyone be kind enough to make a few suggestions regarding pulling some more power out of a V-6 with 150k miles on it? I'm looking to pull maybe 2500 - 3500 pounds of small teardrop-style travel trailer after spending ten days running around Michigan with a motorcycle tent camper (GVW about 700 pounds - 350 empty plus camping stuff) and finding out we don't like setting up and breaking camp in the rain every day so much. That said, I was pretty unimpressed with the truck's ability to go - and stop (that's another thread in the wheels and brakes forum). For this purpose, the 262 V-6 seems to be the worst of all worlds - it has the power of a 4 cylinder with the gas mileage of a V8.


Curious if anyone has thought this way - I see lots of high hp build and engine swap threads but not so much about generating some additional horsepower and significantly more torque for pulling. I'm thinking 250 hp and 300 - 350 lb-ft torque at the rear wheels? Any ideas? I was wondering about going .020 over, porting and polishing the heads, new pistons, new main and rod bearings, and maybe a custom cam grind for the torque? Or should I just put a bigger throttle body and a different tune on it? At the very least, I'm going to upgrade to a full aluminum radiator - two or three rows if such can be found, plus a second transmission oil cooler. At 150k miles, it's not using oil other than a timing cover leak - I only replaced 1/2 of a quart of oil during the 3500 mile trip.



Thoughts? Thanks in advance for your wisdom.


Bob


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post #2 of 16 Old 06-22-2019, 06:49 PM
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Re: Suggestions for 150k refresh for more power?

You didn't say what year you're working with, but that said, I think you're going to spend a lot of money on a non starter looking for 250hp at the wheels. You'd be better off with a sbc swap. Your plan to "upgrade" to a full aluminum radiator probably isn't necessary unless you plan on tackling a lot of hills. A properly recessed, and sealed stock radiator should do the trick. A set of Intrepid fans will handle airflow. You didn't say what kind of trans cooler you have, but if you check the Derale site, or call them, they can recommend the proper trans cooler.


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post #3 of 16 Old 06-22-2019, 08:24 PM
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Re: Suggestions for 150k refresh for more power?

You should definitely tell us what year you have. That makes a huge difference.

1996 and later Vortec V6 is pretty torquey and has decent power. I've seen SUVs with that engine pull 4800-5000 pounds of trailer and boat without issues. If you have that engine, and it's not getting the job done with a 700 pound gross weight trailer, either there's something wrong with your engine/drive train (including intake and exhaust), or you're just expecting too much.

An external transmission cooler is a really good idea℠ if you're pulling a trailer of any significance. Honestly, with 700 pounds behind the thing, the stock cooler in the radiator is probably adequate. Make sure your fan clutch is good, and make sure your radiator isn't clogged. If the coolant has been neglected, especially if yours has the heater core bypassed, a fresh new radiator might also be a really good idea℠.
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post #4 of 16 Old 06-22-2019, 10:47 PM
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Re: Suggestions for 150k refresh for more power?

Those are all good ideas. Try the factory CPI camshaft used in the early 90's as it will work well with the stock PCM. Free up the exhaust system and maybe consider changing the rear axle ratio to a higher one for the torque.

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post #5 of 16 Old 06-22-2019, 11:15 PM
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Re: Suggestions for 150k refresh for more power?

I see in your other thread that this is a 2000 ZR2.

You shouldn't be "underpowered" with that truck. That's got the 4.3L Vortec V6. Check for any exhaust restrictions which might be limiting power. Put a new fuel filter in it if you haven't replaced it within the past few years. That's a 30,000 mile maintenance item that's always neglected. Check your plugs and wires. If they are the original plugs, replace them with AC Delco 41993 Iridium plugs and high quality plug wires. The best are the AC Delco 746KK "Original Equipment" wires. I've had decent luck with Denso or NGK wires, although they don't last quite as long as the AC Delcos (or as long as the AC Delco iridium plugs). The Denso's start getting crunchy and putting on a light show on a wet night at 50,000 to 60,000 miles. But you can buy 3 sets of the Denso wires for the price of the Original Equipment AC Delco wires. Do not use the AC Delco "Professional" universal wire kit. You have to terminate those yourself. If you're really talented at terminating wires, you can make a decent set from that kit, but it's nowhere near as good as the Denso wires, or the AC Delco original equipment wires.

Dizzy cap and rotor might need new AC Delco parts as well. Inspect. If in doubt, those parts aren't very expensive.

Someone has already mentioned the 1994-1995 CPI camshaft. If you're tearing down the engine for other reasons, that camshaft will give you a little more power and torque, even with the stock tune. It's not going to be a huge difference, but you don't need a tune for it either. It's probably not worth doing just for the camshaft change, though.

Check your gearing (you can check the RPO codes on the SPIDS in the glove box, or use this as a good reason to change the lube in the rear gears and read the numbers stamped in the edge of the ring gear. For towing any trailer, I'd want 3.73:1 (RPO code GT4) gears at a minimum, and with the larger tires on a ZR2, 4.10:1 (RPO Code GT5) would be even better.

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post #6 of 16 Old 06-23-2019, 12:31 AM
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Re: Suggestions for 150k refresh for more power?

Pretty sure the 98 up ZR2's all come with 3.73 gears. I am sure they also have the HD 8.6 rear differential. As Racer-X says you shouldn't have trouble pulling a trailer with that truck unless it's in real need of a tune up. It's about as torquey as an S-10 can get. 200HP and 260#ft from 262 cubes is a decent amount for a stock engine. A cam and head work won't add that much. The one thing that may be a decent return on investment is a good free flowing exhaust. Maybe 20 hp and torque.

If you really need more pulling power consider a 2001-2006 Silverado 2500HD with the 6 liter. Your truck and $5K should get you into a decent one. Not a low miles show truck, but a decent running not too rusty truck. To get the HD's 300HP and 360#ft from your 4.3 would cost a lot more than $5K.
I have a 98 ZR2 with the same motor and an 04 2500hd. There is no comparison. The ZR2, although a powerhouse for an S10, is wimpy compared to the LQ4 in the Silverado. Plus the heaver truck has the 4L80E trans which is way stronger and the Tow/Haul mode switch for towing, so you can tow in OD. The PCM only lets it go into OD when it won't hurt the truck. Like flat land towing. Also 4.10 gears are standard.

Bottom line is I see 3/4 ton trucks hauling 6000 trailers at 70 mph many times every day. Can't remember the last time I saw a trailer behind an S10 on the highway.
Just my opinion. I'm sure many folks will disagree.
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post #7 of 16 Old 06-23-2019, 09:26 AM Thread Starter
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Re: Suggestions for 150k refresh for more power?

Okay, many, many thanks for all that. Good to hear, actually, as my expenses just went down a whole bunch. The truck is in good shape and I did a major tune-up just before the trip at 145k - new Delco platinums, new Delco wires and distributor cap, fuel filter, air filter, etc. Top shelf all the way. It ran much better after the tune-up - pretty sure it was the first time the plugs, wires, and cap had been changed. A transmission fluid flush/filter change revealed no issues but it also appeared to be the first time that had been done (that's a 50k item for me - I was religious about it with the '96 Tahoe and it payed dividends in long life). Did not flush the radiator as the fluid is clean and tests well in the anti-freezing department and temps aren't an issues in normal driving. It runs fine on its own and pulled the trailer on flat ground as if it wasn't there, sticking to mostly 55 - 65 mph speed limits on the back roads. I can confirm the 3.73 gearing. Radiator is the original with the internal oil cooler. Hills and East Tennessee mountains (of which there are plenty), were what caused me to wonder about the power issue. It didn't really respond too well to long, steep grades. Had to really feather the throttle and pull the tranny into lower gears to keep it from hunting every 5 seconds and temperatures rose quickly from 180-ish to 210-ish on the gauge, which made me a little nervous.

That said, I don't have any particularly good reason to tear down the engine - just repair the leaking timing gear cover. I'll probably replace the water pump while we're in there just because it will be open anyway and I prefer paying only once for that labor. Sounds like a second external transmission oil cooler is in order and the bigger radiator may still be on the table. I'll ponder that one a bit. But let me ask the next question about free-flow exhausts. Coming from the Miata/Mustang world, free-flow also meant free extra decibels. That's great fun and all but I'd prefer to keep it quiet this time. Headers, duals and stock mufflers? Headers and freer-flowing but still quiet aftermarket options for the single exhaust? Other? Are there intake options - bigger throttle body, etc?

Again, so many thanks. It's been years since I've been involved with a V-anything old enough that it responds to changes without messing (too much) with a computer.


Bob


Edit: just now thought that if there's a way to check the cat at the 150k oil change next week, I'll do that...

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post #8 of 16 Old 06-23-2019, 11:52 AM
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Re: Suggestions for 150k refresh for more power?

I just put a Magnaflow Y pipe and high flow cats on mine and it made a pretty good difference in performance. The original cats were getting plugged and causing power loss. Also, the factory Y pipe is pretty restrictive and the Magnaflow is 2inch with mandrel bends. You don't need a bigger radiator as the 4.3 radiator cools 5.3 conversions with no problem. mine runs 190 to 200 in the high altitude (thin air) and lots of steep grades with no problems. When I got my truck the cooling system had been neglected so I gave it a good flush and a new stock style HD radiator from Ebay for less than $50. I also have a mandrel bent exhaust system from cat back that is 2.5 inch to a Flowmaster muffler that has dual 2.25 out tailpipes. It has a nice low rumble without being too loud. If all I wanted was the same as you, I would be happy with it, but as you see in my signature a V8 is in my future. As for the trans cooler, the plate and fin style that is built like a radiator are much more efficient than the cheaper ones that put fins on round tubing, another case of you get what you pay for. I don't know about a 4X4 as I have never driven one with a 4.3, but I would have no problem with pulling your trailer with my 2wd.
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post #9 of 16 Old 06-23-2019, 12:50 PM
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Re: Suggestions for 150k refresh for more power?

A few things.

When you replace the water pump, replace the fan clutch as well. Those two parts should be replaced as a unit (although you have to take them apart to get the fan blade assembly moved from the old parts to the new parts.

The front cover is replaced as a unit if you have leaks from either the seal or cracks in the front cover. If I have it that far apart, I'd put a good timing set in there as well. Cheap insurance if you're planning to keep the truck longer term.

About the anti-freeze. Test the pH, or just replace it and flush the system when you do the water pump. The issue isn't losing the "anti-freeze" capabilities, the ethylene glycol lasts basically forever, so an "antifreeze tester" will show it good even if it's very old. DexcoolŽ gets very acidic when the corrosion inhibitor package degrades over time. It will eat heater cores, radiators and intake manifold gaskets when it gets acidic. That's why most 1990's and early 2000's Chevrolets (not just S series) have bypassed (or leaky) heater cores. "Long life" or "extended life" antifreeze (including DexCoolŽ) last for 5 years (or 150,000 miles if you can rack that up in 5 years). It's whichever comes first.

You mentioned throttle body options in the opening post, and asked about that. Leave it alone. It's significantly oversized for the engine. There's even a lip piece on the thing to block one side at tip-in (off throttle, to about 5° to 10° opening) so it's not overly touchy off idle. There's maybe 2hp in grinding off that lip, but the down side is that it becomes a very tempremental and touchy beast just off idle.

On the exhaust side, some "shorty headers" are good, and there's a Magnaflow crossover pipe/catalytic converter assembly availble for most of them (not legal in CA, but I'd move if that was your only issue ). The Y pipe (AKA crossover pipe) is the big restriction on these engines. You can also get someone to fab up a bigger one (2.25" or 2.5" diameter is good), but that'll be a custom piece.

Using a 3 inch pipe and 3 inch universal cat on the mid pipe assembly gains a bit, although I think for your year ZR2, that bigger cat is included in the $400ish Magnaflow assembly. You'll get better performance without a lot more noise with that Magnaflow crossover pipe/cat. If you want more noise and a bit more power still, combine that with a cat-back system you like the sound of. A 3" in dual 2.5" out FlowMaster (or knockoff) with dual outlets can have a nice sound. Just make sure you have the spare tire mounted when you get it installed, or your exhaust shop might route the pipes through the space for the spare tire. Don't ask me how I know this (that wasn't me, it was actually done by the previous owner of mine).
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post #10 of 16 Old 06-23-2019, 05:24 PM
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Re: Suggestions for 150k refresh for more power?

Mine isn't noticeably louder with the Magnaflow Y and cats, and I got mine for $320 shipped from Rock Auto. It is 2 inch to the Y 2.5 to first cat then 3 inch second cat and exit. I don't think headers will gain enough to be worth the investment plus shorties sacrifice low-end power for top end, so not so good for towing or fuel economy. I don't think anyone makes affordable long tubes for the 4.3. My cat back exhaust was very affordable from Ebay for about $213 shipped.

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post #11 of 16 Old 06-24-2019, 03:52 PM
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Re: Suggestions for 150k refresh for more power?

4.3L = 262.13 ci. = Bore 3.92in. Stroke 3.62in. x 6 cylinders.
Increase bore by 0.020" = 264.82 ci.
Net increase ~ 2.69ci... = ~1% increase.

In order for the PCM to maintain desired air/fuel ratio, it'll inject 1% more fuel and 1% more air into the engine. (Or rather the suction of the piston in a larger bore will suck 1% more air molecules in).

The stock 4.3L = 180-190hp depending on year. So yeah, maybe 2hp?

Anyway, the point is boring over is predominately an R&R technique for old worn blocks that have damaged cylinder walls. Since most blocks rarely live long enough to go through two refresh cycles, its common to simply go to the max overbore on the first rebuild since it'll be a few hundred thousand miles (or should be) before that engine bites it again. Ergo 0.030" being common. Though 0.020 and even 0.005" aren't uncommon in the LS family due to cylinder liner thickness limitations on some blocks.

I bored my LS3 0.020" over during my build to freshen it up, but frankly in my hp calcs the 0.020" is like a rounding error, I simply always get to round up a hp or two instead of rounding down haha.

In terms of your engine, I am pretty sure mild performance cams are still readily available or can be ordered from Comp Cams and the like. A cam swap and re-tune would give you a nice little jolt without a huge expense.
If you have to refresh the actual motor (is it knocking, burning oil, low compression, what problems, why?), doing just a standard rebuild + cam swap at that time would be fine. Don't do no exotic headwork, multi angle valve jobs etc. It isn't worth it on the 4.3

Yeah, you can do all kinds of crazy hopped up stuff and make 350hp with a 4.3L (not on regular 87 tho), but for way less cost, a junkyard LS 5.3 would beat you in the numbers department fairly easily. Its part of why most people don't bother rebuilding or building performance 4.3's anymore.

Anyway, yeah, short of a full on V8 swap, just do a cam swap, and maybe a rear gear ratio swap (numerically higher = more in the butt torquey feel, e.g. 3.73's, but worse mpg and higher cruise RPM), have it tuned (by an actual shop, not the mail order bs), and you should be good to go!
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post #12 of 16 Old 06-28-2019, 03:16 PM
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Re: Suggestions for 150k refresh for more power?

When I used my 03 with the 4.3 to pull my 16ft fishing boat in outside temperatures above 90-95 degrees the transmission fluid must have gotten hot as it sprayed tranny fluid out what I assume was a breather/vent. Under side of pickup/front of boat had an oily film on it. I never used the truck again to pull anything remotely heavy. Id be curious how an external transmission cooler would perform.

Truck is still running great with the stock transmission and engine at 228k miles.
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post #13 of 16 Old 06-29-2019, 12:36 AM
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Re: Suggestions for 150k refresh for more power?

You are lucky.
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post #14 of 16 Old 06-29-2019, 11:38 AM
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Re: Suggestions for 150k refresh for more power?

ok- easy way to check cat(if exhaust is UNmolested) unbolt cat- and blow air back thru from tail pipe- should not build a lot of pressure if freeflowing. food for thought- you did most if not all PM on driveline- did not see any thing mentioned on the output end.... tires-correct size/pressure, rear end -correct lube level/condition - brake condition- worn or sticking pads/caliper- hub bearing condition/lub- easy check for those- flat level parking lot- cold brakes- neutral- push short distance- then go drive around and get the brakes good and hot- hard fast braking at speed- thenm check/push in netral again and compare the effort needed to more the truck- and as an after though- check out the rolling resistance on what you are TOWING- tires/lube/surge or elc brake etc.....

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post #15 of 16 Old 07-01-2019, 01:07 PM Thread Starter
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Re: Suggestions for 150k refresh for more power?

Quote:
Originally Posted by Jayhawke View Post
ok- easy way to check cat(if exhaust is UNmolested) unbolt cat- and blow air back thru from tail pipe- should not build a lot of pressure if freeflowing. food for thought- you did most if not all PM on driveline- did not see any thing mentioned on the output end.... tires-correct size/pressure, rear end -correct lube level/condition - brake condition- worn or sticking pads/caliper- hub bearing condition/lub- easy check for those- flat level parking lot- cold brakes- neutral- push short distance- then go drive around and get the brakes good and hot- hard fast braking at speed- thenm check/push in netral again and compare the effort needed to more the truck- and as an after though- check out the rolling resistance on what you are TOWING- tires/lube/surge or elc brake etc.....

Thanks for those tips, Jayhawke. Tires were new and at 30 psi. I'm getting ready to change out fluids in the differentials and transfer cases (final 150k service is happening this week or next) but I topped everything off when I first bought the truck in December. Nothing is leaking. I'll make a point of checking everything else. The folks who installed a brake controller system on the Mustang for our trailer screwed up the wiring but we caught it quickly before the trailer brakes destroyed themselves from being on constantly, so I was especially careful to ensure correct wiring this time from that service shop. And I ran most of the trip with the trailer brakes turned off as a) only one was working and 2) it was overheating and squealing from use pretty quickly. It's not like it's a heavy trailer or anything - about 600 - 650 lbs loaded. So yes, I know I've got to get the trailer brakes up to snuff and I'll likely put new pads/shoes on the truck pretty soon, as well. Ceramic at both ends if possible.

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post #16 of 16 Old 07-01-2019, 04:36 PM
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Re: Suggestions for 150k refresh for more power?

I believe the tires should be run at 35 psi for normal load and mileage. Too soft and they will increase rolling resistance and build heat in the sidewalls.

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