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3.4L DOHC Downgrade?


jeffcanada

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Hello All,

As you know I put my car up in the For Sale section.

Now I am starting to think maybe I should keep it as everything aside from the intake and head gaskets is mint on the car. I was on car-part.com looking at engines for sale in Ontario. I can get a 3.1L for anywhere between $800-$1500CA. I know this is probably sacrilege to put a smaller motor in the car, but as far as I am concerned the 3.1L is a thousand times more reliable than the DOHC and has much better low end torque. I know there is also the possibility of a 3100 or 3800 swap, but I want to stick with what would be the most simple.

How expensive/difficult would it be to pull the DOHC and drop in a 3.1L? How much ($) is motor installation labour, typically? Would it mate up to the tranny no problem? What else would I need besides a wiring harness, and probably motor mount relocation?

Or should I save up the $2K needed to repair my DOHC and take my chances that nothing else will go wrong with it (cough cough, that really isn't likely on a DOHC is it?)

Cheers,

Jeff

http://1992pontiacgrandprix.tripod.com

p.s. If I do this it may mean a DOHC engine for sale that is in great shape except for the gaskets that need changing!

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What years should I look at for the 3.8L? And what are repairs like? I have heard that they are pretty much bulletproof, but are repairs expensive if something does go wrong? I know on the 3.1L most repairs are quite simple and not terribly expensive, and I have had good experiences with them as I drove one to 330000, and my dad's cutty is well over 200000, neither car ever having had an engine repair in its lifetime; just tuneups and a water pump on the one I had . That is probably my single biggest beef with the DOHC. When shit goes wrong it, it is twice as expensive as any pushrod motor to fix.

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well.....I happen to have a 3800 series 1 s/c with 13K on it I'm selling.

it's from a 94 bonneville. rated at 225hp

transmission included.

I was about to put it on ebay.

let me know if your interested.

 

 

marcus

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I'm looking at doing the same thing, almost. 3.4 DOHC to 2.8. I was also going to post a topic on here the same as this one, to see if anyone had done it before. I would think the 3.4-2.8 would be way easier than the 3.4-3.8. The 3.4 and 2.8 engines might actually use the same basic harnesses, I can't think of anything that would be different, a person might get away with dropping the engine in, plugging in the memcal and let her buck. One problem with mine is I'm going from a 4T60E to regular 4T60.

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Whats so bad about the 3.1l? You can get plenty of power from them, either turbo or n/a

 

Nothings bad about them, just the whole downgradeing thing which i don't like. and yeah you can get power from them, but to get it back up to the DOHC power, or close would take a good bit of work and $$.

So why not just drop in a more reliable motor than the 3.4 (3.8) that allready has more power than a 3.1. Thats my logic.

Although 3.1s are definately more abundant.

 

Where to find them? bonnavilles (as already stated) and regals, off the top of my head. Maybe some bigger buicks too.

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All I know is a kid from school has a 3.1 92' GP I've ridden in and it is slower than my mothers 4 cylinder galant, which is already too slow to be on the road safely in my opinion. Your gonna miss those ponies, trust me.

However a 3100 GP is not that bad. My aunt has a 94' GP B4U just like mine and around town it feels faster than my car.

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Whats so bad about the 3.1l? You can get plenty of power from them, either turbo or n/a

 

Nothings bad about them, just the whole downgradeing thing which i don't like. and yeah you can get power from them, but to get it back up to the DOHC power, or close would take a good bit of work and $$.

So why not just drop in a more reliable motor than the 3.4 (3.8) that allready has more power than a 3.1. Thats my logic.

Although 3.1s are definately more abundant.

 

Where to find them? bonnavilles (as already stated) and regals, off the top of my head. Maybe some bigger buicks too.

 

Who says the 3.1 is a downgrade? Yes, the 3800 is a stronger motor, but having owned both the gen II 3.1 and the Series I 3800, the gearing advantage of the 3.1 makes for an almost as fast car. Not to mentioned its lighter weight and the fact that 3.1s sound far better than 3800s.

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Jesus,

 

Just FIX The 3.4 thats in it...

 

if its just head and intake gaskets...crap its 10 usd to have them shaved if they are uneven. the gaskets are easy enough..timming isnt that hard takes an hour for the timming and 2 hours for taking everything apart and another 2 to put it back.....

so a day, day in a half depending on how lazy you are...

 

 

it will cost you about 150 in parts usd and then do it yourself....the tool for timming is easy to make.

 

so why spend 800 to put a smaller motor in when you can just fix the one you have....

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Who says the 3.1 is a downgrade? Yes, the 3800 is a stronger motor, but having owned both the gen II 3.1 and the Series I 3800, the gearing advantage of the 3.1 makes for an almost as fast car. Not to mentioned its lighter weight and the fact that 3.1s sound far better than 3800s.

 

3.4=200hp, 3.1=140hp. 200 to 140 = 60hp DOWNGRADE. I'm not a pushrod hater in any way, two other cars in my family have 3.1s and I drive them on a reg basis.

 

It is also quite possible you will spend more money swapping and working out bugs, than you would fixing the motor thats in there.

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If you know how to do it, you can get a 3.1L over 200HP, without a turbo, for around $1000

 

im so interested in this....! :D

please enlighten me

 

Im not gonna give away my secrets :D

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200 hp for less than 1000 bucks. Crane 260 cam, 3400 heads, 3400 lower intake, 3400 plenum, 62mm TB. Labor yourself, and with gaskets you can do all that for less than 1000 bucks. Getting headers any modifying them to fit the W body (they are made for the N body) would be well worth the gains it will give.

 

btw, thats to get a 3.1 TO 200, not add 200.

 

oops, forgot, you will need a custom tuned chip as well.

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If you know how to do it, you can get a 3.1L over 200HP, without a turbo, for around $1000

 

im so interested in this....! :D

please enlighten me

 

Im not gonna give away my secrets :D

 

now im gonna cry... :cry:

 

how about....

 

say i dont want the 3400 heads, and intake,

is there another way to acheive that w/ pushrods

new roller rockers, maybe...

shall i find better fuel system componants, (injectors, rail, pump)...

and light weight pulleys, a chip, hell, how bout a whole new ECU

drop the ac compressor....

port and polish...

the cam

high compression pistons,

bore out the cylinders...

am i on teh right track, or am i over by 3000$...?

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If you know how to do it, you can get a 3.1L over 200HP, without a turbo, for around $1000

 

im so interested in this....! :D

please enlighten me

 

Im not gonna give away my secrets :D

 

 

high compression pistons,

 

Thats on the right track, definitely. The key now is, do know where to get them for really cheap? I do................

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