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Convertible Performance


peeeot

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I bought some new tires for my 'vert today, and though I've been wanting to get a different car for a while, I've decided to stick with it indefinitely. I don't think I can find a better car for the money.

 

My one complaint with it has been and still is its lethargic performance. Handling is fine, stopping is fine, but it really doesn't enjoy accelerating.

 

In all probability, I'll stick it out with the 3.1 and not doing anything because it still has under 91k miles and doesn't have any problems.

 

But I've been thinking about options to get the car's 3600 pounds moving a bit better, and the most obvious ones to me are swapping in a 3.4 DOHC, swapping in a 3.8 series I (if that's even possible), or turbocharging my 3.1 (my least desired option).

 

Were there any changes made to the convertible structure in 1993 to accomodate the increased power supplied by the 3.4, or should my '91 be able to handle it as-is?

 

 

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i dont think there was anything 3.4 specific at all. I've done a few mods here and there, and although I do have the 3.4, it seems to get out of it's own way fairly decently (at least with stock wheels, i need to figure out the weight differences). Unless you do a swap though, you're not going to get any huge performance boosts, but there are all the little things you can do, like FFP stuff, CAI, etc. I have the dogbone, a K&N (opened the airbox a bit), and an underdrive pulley on the way, and each are slightly noticeable, but probably only to me. Hopefully sometime in the next few years I hope to turbo her, but that's not exactly a bolt on job :lol:

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Okay, thanks for the info. I doubted they would have made any major changes, but I figured it was worth checking into.

 

I think that the real issue is the 3.1's torque output. Both the 3.8 and the 3.4 DOHC offer at least 30 lb-ft more torque. Would that be enough to notice? I think so. The 3.8 makes more torque at lower rpms, too, which is what I really want. I think I prefer lazier engines that don't have to work as hard to get the job done.

 

The 3.8 L27 was only availabe in the Regals from 1990-95 according to this site. I can get hold of one with similar mileage to my current drivetrain for very cheap.

 

I assume a 3.4 would be an easier swap, but that the 3.8 shouldn't be hard if I have a donor Regal.

 

I get the impression that the 3.4 is a bit more finnicky about service too, with the timing belt to deal with and its tight fit under the hood.

 

Would either of these swaps be worth my while? Which would make more sense (cheapest, easiest, least customization, most low-midrange performance improvement, most reliable)?

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what about a 3400 swap? I would run it as an OBD 1 on the existing 3.1 harness

 

 

seriously, I thinkg a 3800 vs 3.4 would be equally difficult. althgouh I think they both were standard with the elctronic tranny.

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Is the electronic tranny something to be avoided?

 

If a 3400 can use the 3.1 harness, that could be good. What would I have to do to calibrate the computer for the different dynamics of the larger engine? Surely it wouldn't run very well under the 3.1 parameters. Would it produce enough extra low end-midrange torque to be worth the effort?

 

Haha, I'm probably trying to get this thing to drive like a normal 3.1l coupe would. I dunno, I've never driven one.

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I think the EASIEST swap if you could find all the parts would be a 3.1 Turbo and HD trans. All would bolt right in and all you would need to do is change the harnes, and swap out the MEMCAL. IMO would be the easiest and coolest.

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You know, I figured that would be really hard to find the parts for, but there are 3 turbo 3.1 engines within a reasonable drive. One of which only has 83k miles.

 

What would I need? Memcal, engine, trans, exhaust piping?

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I'd grab EVERYTHING in the engine bay, rad, intercooler, turbo, transmission, wiring harness, memcal absolutely everything. It'd be pretty much a direct swap into your car and would be easier than going with any other engines. The memcal, you'd want either a Topgun chip or KAZ motorsports chip if not for performance, but for driveability factors. If you have any questions, there are a few guys around who have done the swap and are very knowledgable when it comes to this stuff.

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I'm not sure yet. It has 182k miles. The guy says it needs plugs and wires, and if he has been servicing those pieces, that must mean the upper intake manifold is removed. Said it was running before he took those bits apart, and that he has all of the car's parts. Needs paint. He said there wasn't any rust or dents or anything. I didn't bother asking a whole lot of questions because it would be easier just to go see it in person.

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Oh. Whenever I look at the pics of a 3.4 DOHC it looks like the intake covers up the rear bank or cylinders.

 

Anyhow, he said "it was running fine until I took things apart" and "all you need is tune up. plugs and wires"

 

I figured if all he was doing was pulling plugs out and swapping wires, he would have finished the task and kept driving. So maybe he couldn't figure out how to get to some of the plugs or something. Who knows. I'll find out if I go look at it.

 

I wonder if the interior is all torn up.

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For the rear plugs, all you need to do is pull the weatherstripping at the rear of the engine bay by the cowl, then cut 3 1"x2" slots in the metal lip to allow access of the 1 billion extensions it takes to get to spark plug socket down to the rear plugs.

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Sounds like a piece of cake!

 

Not.

 

I can't help but think critically of a design that requires cutting holes in sheetmetal for the servicing of so basic a tuneup item. I suppose the other option is removing the upper intake manifold, but even that seems excessive for something so simple.

 

An inevitable downside of the transversly mounted v-type engine, I suppose.

 

Okay, not inevitable, there are plenty of cars with big hoods and easier access to both sides.

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It doesn't harm strutural integerity at all. Many people do it will no nil effects. Once your done, pop the weatherstripping back on, and go along your way.

 

Hell... I know GM techs that even do it.

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I did my plugs the first time without cutting anything, i just had a flexi extension, and aside from one plug being really tight, and aside from having to have patience, it wasnt bad at all. not nearly as easy as my old 2.8 in which i changed the plugs like twice a year :lol:, but not bad.

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Even if I had a 91-95, I'd pull the plenum to change the plugs. Forget fucking with cutting notches in the metal. I can get my Cutlass' plenum off in five minutes. As Jeremy said, I wouldn't even bother with the L27. I'd look into the LG5, LQ1, or hell, even the L67. Those verts are heavy.

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The cutlass has been feeling a bit peppier lately. Maybe it's the cold weather, maybe I've just been getting on the gas more, who knows. Maybe it's just happy to be getting some attention, what with the new tires and some cleaning and stuff.

 

Still doing exactly a steady 18 inches of vacuum at idle in park at the transmission modulator port. I've asked before, but I never got a direct answer... is that normal for a 3.1?

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  • 2 weeks later...

I've had a lot of highway cruising on my past two tanks of gas. Most of the time I was between 55 and 70, but a lot of it was on hilly two lane roads and I had to pass people a few times. Anyhow, my best tank average was 24.24 mpg. The best I've EVER had was just over 25. Sound normal for the 3.1 in a vert? The EPA suggests otherwise....

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not horrible.... but could be better.

 

I am going to remove and inspect all my injectors on my 93 vert next week. I know something is wrong there and it results in poor mileage for me. maybe you should remove the plenum and ohm your injectors? is there anything elose you have not done?

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