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Old 02-13-2014, 06:31 PM
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Gm 3800 vs 4.3

Looking for ideas on which engine I should use for my car.

I have a Volvo stationwagon with a 4.3 chevy in it already. Has a nice performance 700R4 behind it. Id like more power, but the options are limited with this engine especially with it being a late model 4.3 with the balance shaft in it.

Also the 4.3 is a truck engine. Its built for lugging around weight, and not so much for acceleration.


However, the 3800 V6 is available in RWD form from a camaro and there are lots of performance options available - including superchargers and turbos that are eiither wildly expensive for a 4.3, or hard to find/not available.

The 3800 is also built for a car. Its got a better balance of HP and TQ and at a better power range for acceleration rather than hauling.

The problem is that I already have a 4.3 in the car, and a nice transmission. I believe a 3800 V6, even RWD, uses a 60 degree V6 "metric" bolt pattern, even tho it is a 90 degree V6, so i'd need a new transmission along with the new engine.

Also temping to put in a SBC, but there goes any hopes of fuel mileage. Atleast with a V6 and a supercharger or turbo, you can make some decent mileage if you keep your foot out of it..

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Old 02-13-2014, 06:58 PM
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I don't think you understand how an engine works. That said, a tpi 350 or 305 or a lt1 with a well tuned ecu running it will have much better power and mileage. If you "build" a tpi 350 for mileage you could probably come close to 30mpg's and 350+hp.

A well built turbo 3800 could also do that. The 4.3l can too but it'll be more expensive.
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Old 02-13-2014, 07:00 PM
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what is your rear gear ratio? I wonder if a lower rear gear ratio would help? Maybe higher stall convertor!
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Old 02-13-2014, 07:36 PM
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It is what it is, anything more you invest in a Volvo is just throwing money away once its no longer stock. Dreams are fine and so is bench builds etc but face it, what you want is a V8 car in the first place or at least one that will be worth building up.

A decent 1 5/8" header and larger single exhaust plus some vortec heads with some pocket porting and a Performer manifold is all I would bother doing to the V6, should get you close to 30-40 hp...you need a custom cam ground if you want more.
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Old 02-13-2014, 09:04 PM
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Quote:
Originally Posted by ap72 View Post
I don't think you understand how an engine works. That said, a tpi 350 or 305 or a lt1 with a well tuned ecu running it will have much better power and mileage. If you "build" a tpi 350 for mileage you could probably come close to 30mpg's and 350+hp.

A well built turbo 3800 could also do that. The 4.3l can too but it'll be more expensive.

Um, I know VERY well how an engine works. And IMO the 3800 is a better engine (than a 4.3), especially for a car. I'm just trying to decide which route to go. A V8 has been considered but I think it would be alot more work and I really dont believe that it is going to make the mileage that a V6 will. Best I could get from a stock 302 ford was 15mpg in my truck and that was it overdrive and it is a small engine. But as far as choices go, I've even considered a ford 2.3 turbo, but there are not really any good automatic transmissions to go behind it.

Now I should mention that I am not trying to go all out drag racing with this car.... its just intended to be a peppy little car to zoom around town in and maybe take on trips. It does that good as it is, but i want more. Its about 185hp/250ft lb right now with 22mpg avg hwy and I think I can get into the 30+ mpg range and 250-300 hp and still be with a V6. If I could do it reasonably with the 4.3 I would and will, but I'm thinking i'm gonna have to go to a 3800. Gearing also comes into play also. I am looking into putting in a 8.8" ford with 3.08 gears to get the RPM down on the highway. Having a 700R4 right now, that provides a low-low first gear that would help compensate for the high gearing. Some transmission governor tuning may be required also tho.
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Old 02-13-2014, 09:06 PM
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Originally Posted by dwwl View Post
what is your rear gear ratio? I wonder if a lower rear gear ratio would help? Maybe higher stall convertor!
Gear ratio is 3.54 in a Dana 30 27 spline axle. As mentioned in the post before this one, I am considering an 8.8" ford with 3.08 gears to get the RPMs down and keep it in the power range of this V6 (considering the small tires).
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Old 02-13-2014, 09:20 PM
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Originally Posted by 4 Jaw Chuck View Post
It is what it is, anything more you invest in a Volvo is just throwing money away once its no longer stock. Dreams are fine and so is bench builds etc but face it, what you want is a V8 car in the first place or at least one that will be worth building up.

A decent 1 5/8" header and larger single exhaust plus some vortec heads with some pocket porting and a Performer manifold is all I would bother doing to the V6, should get you close to 30-40 hp...you need a custom cam ground if you want more.
I do not know what to say here. I want to build this Volvo up because I like it and it is a nice car. I want what I want, and that is to give some people a nice surprise when they try and pick on me because I drive an old Volvo, and a stationwagon on top of that! I dont have to pick on corvettes or anything like that, but todays cars are high powered, and I want to keep up with them and maybe be a little bit ahead. I do not want to give up a whole lot of mileage to gain this either. I want to have what the car makers cant build due to regulations, but I can.
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Old 02-13-2014, 09:21 PM
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tpi 350 would be a good choice.
Iyo,what makes the 3800 a better engine? I use numbers to say an engine is better,ie SFC numbers
or strength issues like 2 bolt Vs 4 bolt, or steel Vs cast,,,,
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Old 02-13-2014, 11:31 PM
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How about a Ferrari drivetrain, only slight mods required to adapt. Maybe a big turbo or supercharger, those modern cars wouldn't mess with ya then.

You could cut apart one of those supercharged Bonnevilles and slide the chassis under the Volvo body and after a little welding your rockin.

I know you dont want to mess up the factory Volvo superior handling but maybe a Chevy truck chassis wheelbase is similar, then you got a lifted Volvo 4X4 with a v8.

Have you considered nitrous? Cheapest HP upgrade you can get and your mileage stays the same.

What about a Porche Cayenne drivetrain?

Wait...two seconds of Goggling finds me a Supercharged LS powered 1975 Volvo 242! Wooooo baby! Think of the resale value!

http://www.hotrod.com/featuredvehicl...975_volvo_242/
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Old 02-14-2014, 12:15 AM
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the 3800 is much better than the 4.3 now if they ever make a 4.0 v8ls.. that be something..
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Old 02-14-2014, 07:50 AM
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The 3800 isn't a bad engine, but you're going to need some work and money to get it to be a great engine. You never mentioned a budget, 5K, 10K? Usually people want mileage to save money, but I'm sure you know this is a loosing money proposition from the starting line. I like mileage just so I don't have to stop at the gas station as often- I also like larger fuel tanks for the same reason.
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Old 02-14-2014, 07:59 AM
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now the 3.6 turbo in catty's is nice..
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Old 02-14-2014, 09:51 AM
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Odd my friends V6 half ton truck gets worse gas mileage than his dads V8 one. Identical trucks except for the powerplants

Lowering your rear axle ratio to a 3.08 is a seriously misguided idea in the hopes of some kind of "performance" You want more spirited performance, and you're going away from torque for an interest in economy. A 3.08 will cause you to be more heavy footed from stoplights and on freeway entrance ramps. Unless you spend literally ALL your time on the freeway, theres no way tooling down the interstate at 1400rpms and probably lugging the engine every time you go up a modest hill, is going to overshadow pushing the engine harder to accelerate the same as it does now. I wouldn't go any lower than a 3.23:1, even with your tiny rear tires. A well maintained factory roller cam 350 TPI corvette, camaro or Firebird with a 700r4 and 3.23 or 3.42 rear gear got great mileage, and the performance from 0-4500rpms makes for great performance from light to light. These cars in stock trim can do in excess of 130mph. Another option would be an LT1 engine matched to your 700r4. Id also imagine if you have a "prepped" 700r4, your converter is wrong for your goals.

If it was me; Id get a 1991 corvette TPI 350 and 700r4 and OEM harness. You get aluminum heads, roller cam, a seriously cool looking intake system, that fits under a low hoodline, and is engineered to do what you want. I imagine it weighs very little over your balanceshaft equipped 4.3 and will make 340ft pds of torque at 4000rpms, 250+hp and sip 87 octane junk gas and be happy tooling down the road at 1800rpms.

Or turbocharge your 4.3 and probably make 250 honest HP for 5 grand in cost and a ton of fabrication. Don't go to a smaller engine for better performance.
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Old 02-14-2014, 10:23 AM
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if you turbo a 4.3 and only hit 250hp- you need to close your wastegate. a turbo 4.3l with 5k in it should be closer to 500hp+.

That being said a used LT1 or TPI engine is a lot easier and cheaper. and they do work well. I would NOT advise cruising at 1800rpm though, 2000 at a minimum if you care at all about bearing wear.
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Old 02-14-2014, 12:13 PM
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if you turbo a 4.3 and only hit 250hp- you need to close your wastegate. a turbo 4.3l with 5k in it should be closer to 500hp+.

That being said a used LT1 or TPI engine is a lot easier and cheaper. and they do work well. I would NOT advise cruising at 1800rpm though, 2000 at a minimum if you care at all about bearing wear.
now I've heard it all
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