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Mike 10-21-2011 01:24 PM

Power to weight ratios?
I posted this under Vans/Motors. I'm moving it to General for increased exposure (and ridicule?). 8)
I've got the '02 Chev 3500 Express van with the 350CID V8 (5.7L?). No idea how much HP or torque it has, but the fuel economy is pretty good. No matter what the rated power output is, it is a heavy vehicle with the extra equipment Roadtrek added when they converted it. I think it weighs in at around 8500 lbs. tanks empty.
I was wondering how to get more power from it, or as a second option, was there a larger factory engine/transmission available in that year, that would fit under the hood, with minimum additional mods to the engine compartment, and drivetrain (I'd expect possibly a shorter driveshaft) if I decided to change out the existing engine for a larger one? I'm prepared to sacrifice fuel economy for increased power.
Who or where could I go to follow up on this idea? GM dealer? Custom engine shop?
I think I'd like more power, or a more powerful engine, for driving up hills in the mountains.
Thoughts, suggestions, recommendations?

Dieps 10-22-2011 04:07 AM

Re: Power to weight ratios?
Mike - I'm not sure about engine options for '02 RT's. If you check, you can download your 2002 owners manual. If I am reading it right, the 170 and 190 models were on a Dodge chassis and the 200 was on a Chev. chassis. It says Chev. is 255 HP/330 ft.lbs. Please check it to make sure I'm right.

This is kind of comparing apples and oranges but my '08 190P has the 6.0L engine. It is a few hundred pounds heavier than yours so the power to weight ratio might be close to the same. Like you, I was concerned about maintaining speed on mountain roads but I've found it's never been an issue even with full tanks. I've not been in the Rocky's but traveling the eastern mountains has been easy going.

I have a friend with a '94 RT with a 318 engine. He says it is underpowered but he has managed to put 220,000 miles on it so I guess it can't be all that bad. Good luck and happy trails.

Mike 10-22-2011 04:58 AM

Re: Power to weight ratios?
There were 2 190 models my year, 4 models in total. There was a 170 and a 190 on a Dodge chassis, and a 190 and a 200 on a Chev chassis. I have since looked at the brochure for 2002 which has more technical specs than the owner's manual. The 200 had an optional 8.1L SFI V8 but my 190 didn't. I'm wondering if that engine might be able to be fitted into the 190 3500 extended van chassis. I'll probably run this by my GM dealership and see if it's possible, and it's feasible money wise. I'm sure it would solve my power issue.
Anyone on here have any experience with the Chevy 8.1L V8? Powerful? Fuel economy?
I agree about eastern mountains. Generally speaking I've not had too much trouble in them, once in a while it lugs up a grade greater than 6-7% rate of climb.
The western mountains are a different animal. You learn defensive hill climbing very quickly, how to flip the 4 ways on and move right, how not to get trapped behind an even slower moving truck, also struggling up hill, or at least to keep an eye on your water temperature gauge if you do get trapped. How to spot those grades in advance that will cause you grief. It's fun, really (not!). The down hills can be just as exciting, particularly if your brakes weren't serviced before you head out. :shock:
At least that's been my experience. Others might have different experiences or opinions.
We still enjoy traveling, but we tend to gravitate west, so it's something I'd like to resolve, if possible. We like our van, it's a great way to see the continent, except for this one little bugaboo. If we were Florida bound every trip it wouldn't be an issue. If it can't be resolved, we've discussed selling up to someone who doesn't like mountains, and look for another means of travel to our preferred vacation spots. :think: Perhaps another van with a better PtoW ratio, or maybe something other than a B?
Anyway, sorry for the monologue. Thanks for the thoughts. :D

Dieps 10-22-2011 01:40 PM

Re: Power to weight ratios?

I'm anxious to get to the western mountains and when we were looking for a van, we looked for larger engines for the reasons you mention. While looking, we drove an RT 200 with the 454 4ngine (I think that's the 8.1L you mention) and it certanly has lots of get-e-up. It's a huge engine block but might fit. Seems like it would be an expensive switch especially if the trans and/or differential has to be switched out to match to new engine. Good luck.

I'm anxious to experience the western mountains. The 6 - 8 degree grades in VA or western NC have not been a problem. I'll down-shift every once in a while for both uphill and down but as you say, it's a whole new ballgame when you go west. Maybe we'll get there next summer.

Mike 10-22-2011 02:03 PM

Re: Power to weight ratios?
Thanks for the anecdotal opinion. Very useful. I'm hoping the motor mounts and driveshaft length will be the only issues, although the Roadtrek brochure mentioned the 8.1L came with a locking differential so that might mean a complete drivetrain replacement, possibly including the rear axle.
Probably not worth it, but there's no harm in asking.
Might be cheaper than a new van. I'll have to "weigh" my options. :wink:
You won't be disappointed with the western mountains. The drive through the Glenwood Canyon portion of I-70 is incredible. You'll be impressed by the roadway engineering, even if you know nothing about it.
Out there, there are plenty of grades greater than 7% (although you usually only get warned about the downhills) so it can be a challenging drive. We think it's worth it, even with our current vehicle, and visit the west often.

booster 10-22-2011 02:56 PM

Re: Power to weight ratios?
IIRC the Express van was changed in 2003 and the 7.4 litre was dropped as an option. I have heard that when they did the change they made the engine compartment and doghouse smaller, so an 7.4 into a 2003 and up probably is a no go.

It could be done into your 2002, however. The best thing to do is to find a donor van at the junkyard or repairables dealer and swap out the entire drivetrain. You might run into some issues with the Roadtrek parts being in the way, but I don't think it would be major.

Mike 10-22-2011 09:44 PM

Re: Power to weight ratios?
Thanks Booster. I had hoped since the chassis for the 200 had the 8.1 as an optional engine, it might also
fit in the Express van chassis' engine compartment. The doghouse (cowl?) in the cockpit under our dash is large and reminiscent of the rear access cowl in my '79 E150. It's roomy.
I'll run it all by my GM guys next week. It can't hurt to inquire.
They're nuts, like me, so it might be a go even if it won't be cheap or easy (please hold the comments about my personal levels of integrity, thanks :roll: )

Photog 10-24-2011 07:02 PM

Re: Power to weight ratios?
Keep us posted on the progress and idea options.

The standard 350 has many power improvements that can be applied to it. If you go this route, you will want to modify it for increased torque, not necessarily horsepower. Longer crank can get you more torque and more C.I.D.. Ask for the friction-reducing coatings on the new parts, to reduce heat of operation. There are other things too, if you go that route.

Mike 10-24-2011 07:11 PM

Re: Power to weight ratios?
I'd love to find a crated 496 or 454, as either would do the trick. If I went the rebuild/re-engineer route, I'd try to get the most wear resistant parts, as longevity is as important as performance long term, when spending money on this sort of thing. I would treat it like any other investment. It would also be a bonus to find that it's not as expensive as I already expect it to be. :idea:
TY, for the suggestions. It's all good as far as I'm concerned. :)

Mike 11-01-2011 08:55 PM

Re: Power to weight ratios?
UPDATE: Got a reply back from GM Canada and they basically passed the buck to the local dealer.
He finally got back to me and suggested upping the size of the motor brings with it a host of other
issues, none of which are minor. According to him, almost every related system and control either
mechanical or electronic would have to be changed too. So he suggested trying a performance engine place that simply reprograms the OBD or control module to squeeze 30 more HP out of the engines,
which probably isn't worth the trouble. I doubt 30 HP will make any noticeable difference in hill climbing ability.
So I'm searching for a real tearer down, and rebuilder of engines. Someone who knows what things might actually help this little V8 do more.
Any one ever taken their car to a performance shop nearby?
That '65 Coronet 440 must need an occasional visit to the torque clinic?
I used to know a guy who bought a slightly later model GTX with the Super Commando 440.
Probably one of the fastest cars I've ever been in.

booster 11-01-2011 09:07 PM

Re: Power to weight ratios?
These guys are local in the Minneapolis area.

They do lots of marine and truck engines, as well as race and high performance stuff. They are pretty reasonable compared to the high end race shops and seem to get pretty good results. They also are big into GM stuff.

Mike 11-02-2011 01:35 AM

Re: Power to weight ratios?
Thanks booster. That's exactly the type of place I'm looking for, I guess.
I googled performance engine mods and came up with a handful of shops nearer my neck of the planet, so we'll see if anyone gets back to me locally, but if not, maybe a road trip will be in order.
Wonder if they'd let me sleep in the van while they did the engine up? 8)

booster 11-02-2011 02:19 AM

Re: Power to weight ratios?

Originally Posted by Mike
Thanks booster. That's exactly the type of place I'm looking for, I guess.
I googled performance engine mods and came up with a handful of shops nearer my neck of the planet,
so we'll see if anyone gets back to me locally, but if not, maybe a road trip will be in order.
Wonder if they'd let me sleep in the van while they did the engine up? 8)

With some of the shops, and almost certainly Wagamons, you can get them to build you an engine from one of their "core" engines, just the way you want it, and then they keep your engine when the swap happens. That often makes the changout a one day affair, rather than closer to a week, if they did your engine.

Mike 11-02-2011 01:53 PM

Re: Power to weight ratios?
Just got a reply back from one place nearby, and I quote,"there's no replacement for displacement".
They say it could be stroked to a 383/360HP with relative ease.
I'm trying to get more info from them about it all. I will be calling shortly.
It looks like it would have to be a tear down rebuild the lower half of the engine, but there might
also be an opportunity to do the cam, valves, springs, and to blueprint the engine at the same time.
Based on a 20 minute conversation I had with the proprietor of the Active Engines Performance
Machine Shop, I expect the cost to be between $4000 and $7000 depending on what I decide to do.
That's around 22 hours to remove and replace the physical engine, as it has to be pulled out of the
front of the van, and all parts, and any polishing and millwork, and any other odds and ends. He
has suggested I may gain as much as 40% in torque and power over the stock numbers.
So it's possible. The question is, is it worth it to me?
Here's their website. Lots of juicy stuff for us automotive-techno-geeks.

Photog 11-10-2011 05:55 PM

Re: Power to weight ratios?
An engine that produces 40% more torque would be a huge improvement for mountain driving.

If they can build a reliable, cool running stroker (383), that would be the easiest engine solution. If they use a longer (5.7") connecting rod, 3.75" crank, the 062 casting (or equivalent E-Force) heads, and the proper roller cam, you should have the foundation for a strong, cool running engine.

At the same time, you will want to know what RPM range the new engine will be pulling strong torque. You will then want to have the correct gears installed in the rear axle, so that this RPM and desired speed, line up with either 3rd or 4th gear in the tranny. (e.g. 50MPH, @ 2200 RPM, in 3rd gear). I hope all that made sense.

This same approach may help with your current vehicle/engine (gears are less expensive than engines). Flat-land gearing is set up different than mountain gearing. My 2009 190V has 4.11:1 gears in the rear axle, and a 6.0 Vortec under the hood. I have no trouble in the mountains. A flat lander may come with 3.73:1 gears, and this would have a hard time in the mountains. A trip to a dyno would help understand what your torque/hp curves look like (today). Then you can calculate the rest of the numbers to determine the optimum axle gear ratio.

On another note: When a shop reprograms your OBD2 controlled computer, it is only Wide Open Throttle (WOT) that is programmed. I think the EPA made the manufacturers lock out the "normal" portion of the OBD2 control system.

Just more food for thought.

Mike 11-16-2011 10:26 PM

Re: Power to weight ratios?
I'm putting this on the back burner for now, with winter closing in. I was thinking I might get a slightly better deal on labor, if they're starving for jobs in the cold weather months, but for now it can wait.
If/when I proceed, I'll add updates.

Barman 12-29-2011 02:14 PM

Re: Power to weight ratios?
Our 3500 Chevy 190 is a 2006, and I can tell you that the 6.0 engine with the 4:11 rear end is a real power house. We have done plenty of mountain driving, and trailered also. Our RT has never wanted for additional power. I am amazed at the terain it will climb without even having to downshift. When it comes to MPG we average 15, but have achieved 19 in ideal conditions. I feel that this engine delivers a great combination of fuel economy and power for your needs. If you were able to find one in a bone yard it might be what you are looking for.

Mike 12-30-2011 01:58 AM

Re: Power to weight ratios?
It might be. So, you have a 366 cubic inch engine? 6L? Unfortunately, I'm not familiar with that engine size or configuration. It's only 16 cubic inches bigger than what I've got now. Maybe newer technology makes a difference, too.
According to the RT brochure for my year I have 255 HP/330 ft.lbs. and a 4.10 rear axle ratio, however
these numbers are from the Roadtrek Brochure, not from GM, and I am not always certain they get it right. Looking at your year, your engine has 300HP and 360ft/lbs of torque so it's 20% more HP and about 9% more torque than mine. Your rear end ratio is 4.10 according to the 2006 RT brochure, so we're even there. Our empty vehicle weights are comparable. So, I guess the extra HP and torque make the difference.
Could be mine is just older and maybe more tired. I've taken very good care of it, but like us, they age. It's got just over 210,000kms on it.
I've already found out from GM that swapping a different sized/configured engine isn't economically or technically as easy as rebuilding the one I already have. That's from GM/Chevrolet.

Just curious, when you say mountain driving, it would be useful to compare frames of reference.
As examples of stretches of road where mine has some difficulty with grades higher than 6-7%, have you driven the stretch of I-70 from Denver, CO to Grand Junction, CO? That's one of my nemesis freeways for climbing. I have also have some lesser issues on unknown back roads in the PAC northwest near Mt. Rainier and Mt. Hood, US89 south of Page, AZ, and have had issues trying to climb some hills on I-79/I-77 and US19 in WV, and also at the access road to the ski hills in Lake Placid, and sections of the Cabot Trail in Cape Breton.

Barman 12-30-2011 08:17 PM

Re: Power to weight ratios?
We have not been out west as of yet with our RT. We have driven thru W. Virginia and been on 19, 79 and 77 all with no issue. We have also traveled all thru the smokies and to tell you the truth I remember seeing the percent of grade signs, but really don't recall what the grade was. Our RT handles the grades so well I really don't concern myself with it. It is actually more concerning coming down than going up. I have never had an issue coming down, but I am religious about down shifting and letting the transmission handle the load and not using the brakes unless it is necessary. We have also traveled thru Pa. in some pretty good grade areas without any problems. I read on different forums, of handeling issues, power issues and braking issues that some of the folks are having with the Roadtreks and Pleasureways, but praise the Lord, we have been blessed in our travels with no problems and great times.

Mike 12-30-2011 09:26 PM

Re: Power to weight ratios?
Glad to hear you haven't had any issues in the eastern hills. It may just be 4 years newer technology and the extra HP and torque ratings on your newer chassis. If you ever get out west, and remember this thread, If you can, would you post up your hill climb findings?

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