PontiacBonnevilleClub.com

Hey everyone, I was surfing GMForum.com and came across an interesting thread:

http://www.gmforum.com/performance-brai ... le-296156/

The general idea is making an LS4 powered Pontiac Bonneville. I know that it's been discussed on this forum a bit, but I'd like to open the can of worms again. The above thread brings up two interesting topics--AWD and using a manual transmission.

I'd like to stay away from the "too much money--just buy an Imp SS" arguments. The truth is that the Bonne GXP is, in my opinion, one of the most beautiful cars ever made and mine never stops taking my breath away when I walk out to it. The longer that I hold onto it, the more that I realize that parting with it is becoming less of an option.

Please understand that my mechanical background is limited at best.

So, what would it take to put an LS4 into the Bonneville (and preferably not use the trashy transmission that comes with it). AWD would be excellent too, and that thread talks about using the transfer case from a Pontiac Aztek. I'm not so caught up on the manual transmission idea, but there were some musings of the F40 from a G6 GXP.

I understand that there would be extensive tuning and fabrication involved, but does anyone think that this could be feasible? I was thinking that in the next year or two I might trade in my Bonnie and buy an Imp SS instead of a G8, save myself a few thousand dollars and then use that money to buy a 4th gen Formula Firebird. If the AWD could work, I might keep the Bonneville and buy something that's good on gas instead of having two V8 powered gas guzzlers.

Please forgive me if I sound stupid, but this sounds like it would be a cool idea.

Please ignore this post. I did a bit more research and found that this whole idea is romantic and stupid involving a mechanical comprehension surpassing my own.

Well, Ive put a bit of thought into AWD, but never an LS4. One big issue I would see with AWD would be getting the driveshaft and steering rack to play nice. Exhaust would be a custom fab job. Last and certainly not least would be grafting in an AWD rear subframe. Not sure which vehicle would be best suited as a donor, but im guessing a minivan would have the lowest profile, allowing the least intrusion into the trunk and back seat.

The transaxle issue seems like a simple matter of beefing up a Volvo unit, but I could be wrong.

I dont know much about how one would integrate the electronics but Im pretty sure youd have to loose traction control and stabilitrak.

After playing with an XC90 with bald tires in the snow, the AWD fantacy got pretty strong in my head, but like you said, its pretty far fetched.

Yeah, I think that it would take a significant amount of engineering. A custom fab job for the exhaust would likely be the easiest part of the project. I like the idea of an LS4 because of the mod market, but the garbage transmission is certainly an issue. I wouldn't mind losing traction control too much--it would wind up being a weekend cruiser/Mustang killer, and my Stabilitrak doesn't work anyway...

I did see a Monte Carlo (I believe pre-2000 vintage) that had an LS4 swapped in, and the owner was also able to swap in the interior from an 06 Monte (not a bad idea considering how much I love the interior of the 06 Imp SS).

How much would it cost to have a rear subframe put in?

How dirty would an AWD LS4 GXP Bonneville be?

If you're not able to do 99.999% of the work yourself, don't even consider it. It's still going to cost a LOT, and the car will be worth nothing to anyone but you when you're done.

Hmmm, I see. I certainly wouldn't be able to do any of the work myself.

But you don't think that out of all of the folks that I've seen bemoan GM for not offering RWD options on the Bonneville, Imp or MC, none of them would be interested in a moddable, professionally executed alternative drive example?

No, and you'd take a HUGE loss. You'd be way further ahead buying a G8. Labor is $75+ an hour, and there are going to be a LOT of hours in there, PLUS all the parts you'd need.

I'd like to stay away from the "too much money--just buy an Imp SS" arguments. The truth is that the Bonne GXP is, in my opinion, one of the most beautiful cars ever made and mine never stops taking my breath away when I walk out to it. The longer that I hold onto it, the more that I realize that parting with it is becoming less of an option.

You don't need to take me to school about the impracticality of such a venture, I included the term 'Just For Fun' in the title for a reason. I'm mostly concerned with the hypothetical, and I don't appreciate the implicatios that you typing certain words in caps makes... Cost is more of a point of interest than a thread closer.

I do, however, promise you that you're dead wrong about not being able to find a single person who would find the car worth buying. The fact that there have been multiple threads about RWD conversions on some of these cars is strong evidence against your argument.

I won't contest that you'd never get your money back (interestingly enough, though, that argument doesn't stop folks from building 12 second Bonnevilles or 10 second f-bodies that they'll never get their money out of).

Not that it matters--if I or anyone else would be to do this, I would hope that it would be obvious that resale value isn't a primary concern.

I understand that the amount of money that it would take to get a Bonneville to basically the same point, performance wise, of an LS4 powered car would be several thousand dollars in parts and labor. Taking into account the additional costs of powering the rear wheels puts the cost of conversion probably in the range of $15-20k. That's without changing the power output of the LS4.

Correct me if I'm wrong.

I apologize if you feel my post was being rude. I was just trying to emphasize the point.

Here's the thing: There's been a lot of discussion. Lots of us would have loved it if GM did it. But if someone was truly willing to pay for it, don't you think they'd have already paid for it? Talk is cheap, especially on internet forums, and that no one has put money where their mouth is proves my point.

Just buy a Grand Prix GXP or Impala SS if you want an LS4. Granted it will still be FWD. But the engineering needed to package a FWD biased AWD setup, steering, suspension, exhaust, and rear diff, is something that requires a lot. Both in time and $$$... This isn't something you'll start on Friday afternoon and be done by dinner on Sunday.

With all due respect...

I'd like to stay away from the "too much money--just buy an Imp SS" arguments.

I understand that this is an engineering issue--I do have a bit of a background in engineering and was hoping to have a conversation on that level. I'm not a parking lot king looking to put a fart can on the back of my Honda. I never expected this to be a weekend project (I even admitted that it's probably more of a romantic dream than something that could ever be done). I just wanted to have some fun and shoot the hay with some folks who might have, once upon a time, had a similar idea or who were at least passionate enough about their cars to venture down the 'well, what if...' road with me.

I see this was the wrong place to do that, either for lack of imagination or lack of care to discuss it with me in particular. I'm sorry for that. I guess that we can all go back to complaining about foglights and how much money we sink into our cars for routine repairs.

It's kind of annoying that this thread went down the way it did, so I will go ahead and play in to your hand. I am mechanically minded, yet lack the patience to even consider a project like this myself (a LIM was too much for me FWIW). I will also put your lack of mechanical abilities aside, because you really should be doing this build yourself, instead of paying someone.

First concern: AWD. I believe this to be fairly unrealistic based on the route you are pitching. Aside from the engineering concerns already discussed, I find myself looking at the intended application of the system you plan to use. I believe the furthest that GM ever took the VersaTrak system was in the Rendezvous. A snippet from Wikipedia may help put this in perspective:

In lieu of four-wheel drive, the Rendezvous offered Versatrak, a full-time, fully automatic all-wheel drive system which provided sure-footed traction in the snow and wet, could handle moderate off-road surfaces, but was not meant for boulder-climbing Rubicon Trail-type activities

This system is designed to bolt on to a 4T65 (not HD), behind, at most, the LX9 3500 (Max 201HP/221lb-ft) which is out performed on all counts by the L36 (205HP/230lb-ft), and designed for use in low to moderate traction conditions in its native environments. Assuming you can get it in to the car (hefty achievement points here) and on the back of a 4T80 (is it even possible?), you may begin to discover the limitations of the system are frustratingly low (I may be wrong, I haven't heard of anyone challenging the limitations of the system)

Second concern: LS4. On paper, without addressing the execution, doesn't sound too bad. If you can overcome the transmission issues (4T80 sounds nice), it sounds like it could be a bit of fun, but you would still be left with FWD, which can seem pretty limiting on the fun factor, and somewhat sketchy when it comes to putting stupid power down.

Overall, I have only seen 1 Bonneville putting power anywhere other than the front wheels, and that was a long time ago. I believe it was a 92-95, that was built on a caprice chassis, with a Bonneville Body dropped on it. I tried finding pics of it briefly, but came up short. I will try and find more details on it.

Thought, a body swap may be more feasible for what you want to do, but I wouldn't even know where to begin with that.

04BlackGXP wrote:With all due respect...

I'd like to stay away from the "too much money--just buy an Imp SS" arguments.

I understand that this is an engineering issue--I do have a bit of a background in engineering and was hoping to have a conversation on that level. I'm not a parking lot king looking to put a fart can on the back of my Honda. I never expected this to be a weekend project (I even admitted that it's probably more of a romantic dream than something that could ever be done). I just wanted to have some fun and shoot the hay with some folks who might have, once upon a time, had a similar idea or who were at least passionate enough about their cars to venture down the 'well, what if...' road with me.

I see this was the wrong place to do that, either for lack of imagination or lack of care to discuss it with me in particular. I'm sorry for that. I guess that we can all go back to complaining about foglights and how much money we sink into our cars for routine repairs.

It's not a lack of imagination. See my thread in the other rides section about me doing either an L67 or an LS4 swap into a Montana minivan. When I posted that, I was hoping one member in particular would post. That member also posted in this thread! It's a lack of available parts to convert it with, cost, and time. All when a LS4 powered vehicle, if you really want one, is only a loan away from being in your driveway, factory engineered, and possibly still under an extended warranty, from GM.

Truth be told, having an LS4 vehicle, in it's native environment as designed and engineered by GM, it's nearly as tough to work on as a Northstar powered GXP. As such, adding in the complication of converting a transaxle to an AWD setup, which would probably require significant front suspension and steering modification, probably some level of exhaust re-routing/modification, and then additional drivetrain hardware that would require more exhaust modification, definitely rear cradle modification to install a diff, etc, it just doesn't seem feasible.

I don't see that the conversation turned negative, just several of us non-engineer types who are the mechnical types (myself who was stuck working on these things for a living at one point in a GM dealership), telling you save your time, money, and hassle trying to actually execute it. That's all.

CMN, I actually stumbled across your thread about the Montana when I was having mental diarrhea about this idea. You were actually one of the folks that I would hope would chime in this time, I was just hoping that your first response would look more like the one you just gave. I really appreciate how much work it would be, and I'm not even saying that it's something that I would do. I just wanted to spark a lively and fun thread. I know that a lot of you are engineers or mechanics and I want to learn more, I thought that a thread like this would be a great way to do that.

I actually owned an 06 Impala SS for about a week before it came to my attention that the treatment the dealership used to cover up the smell of cigarette smoke was temporary and I needed to have my Bonneville back (in light of my smoke allergy). I LOVED the Impala--the sound, the interior, the heated seats, the steering wheel, the increased power over my Bonneville. It almost killed me to give it up. Now I think about getting rid of my Bonneville (which has been a huge pain) for a G8 or another Imp SS and I just don't want to do it. What I do want is the best of all three worlds, a Bonneville GXP with an LSx engine and the interior of G8 (though I would settle for the interior of an 06+ Impala).

Thank you for the advice on just buying an LS4 powered car, I'm completely on board that it would be a much better idea than anything that I'm discussing. I really would just go ahead and trade in the Bonneville for one if the Bonne wasn't so sexy to look at after a hard day of work.

Nice garage, by the way. An LS1 and an LS4... *jealous*

RJolly, thank you for the response. I should say that it wouldn't be so much of a lack of mechanical ability that would prevent me from doing this myself but rather the lack of tools and space. What work I have done, I did with the assistance of a friend who was fortunate enough to have access to any number of lifts and a professional garage full of tools. None of those luxuries are accessible to me anymore.

I thought that I had read, and I couldn't find the link so it's possible that I am mistaken, that the VersaTrak system used a series of clutches to become active when the rear wheels started to lose traction and provided a 60% rear power bias when active. That's what made it seem fun. I agree that if it could be jammed into a car with an LS4 swap, it would likely prove to be the weak link in an otherwise relatively unstable situation. A case study that I find quite noteworthy is that of the 3000GT VR4. AWD and All-Wheel Steering in the later models. It's clear that this particular platform was planned to be utilized in an AWD application, but I'd love to get underneath one and see how it all works. I think, however, that I should give the AWD thing a rest.

On another interesting note, I've read (and seen pictures proving) that the LS4 can be, without a great deal of modification, mated to an F40 6-speed manual transmission from a G6 since the LS4 uses the same bolt pattern as a 60* V6. There's a very detailed thread in which a Fiero owner does just this (Link: http://www.fiero.nl/forum/Forum2/HTML/113207.html). If an LS4 could be put into the Bonneville and things could be adapted within the vehicle to accommodate the 6-speed manual, that could be a lot of fun.

I know that it's not favorable to put a lot of power to the front wheels, but would you do it if you could do it with a third pedal and a slushbox? I'd be willing to give it a go.

Really? Did I just delete a whole page of text? Yep...

I think I speak for the OP as well when I say I realize how impractical the idea is, but its fun to brainstorm about. I guess bench racing isnt a big thing with bonneville peeps.

Im looking into the torque split with the awd transaxles. This would likely determine whether a rear end from a FWD based AWD model could be used. Im guessing they arent very strong. I would imagine something stronger yet still compact could be had from something like an Evo or even a RWD car with IRS.

As for the trans, isnt it pretty easy to beef up a 4t65e to HD specs? Im not fully read on what can be done. Ideally to save the trans itself(anything ahead of the dif housing) one would want as low of gearing as possible. Pretty much all the GM family awd crossovers and minivans had 3.69:1 gearing, but in non-HD trans's.

I shouldve swapped to 3.29s...

Haha, now you got me wondering what setup the new SHO has. I remember a commercial with Carl Edwards that had that car pretty sideways for quite some time.

I think it is the same family as the XC90 mentioned?

I noticed you mentioning having a manual would be fun too. While doing an AWD swap or LS4 swap would be awesome. From a realistic standpoint (I've done major fabrication work on vehicles), your best bet would be to build a Series 3, drop the Northstar. And manual swap. While you wouldn't have AWD or V8, you'd have a fun car that's completely in the realm of possibility.

Here's an idea. All money aside.... and I stress that point...

Find a wrecked high dollar import with AWD and a big engine such as Lamborghini, Audi, BMW, Ferrari, etc. Modify, modify, modify... again stressing THAT point, Until you can fit the GXP body onto it and boom! You would probably be saving money over modifying the GXP itself haha. Hows that for imagination???

I realize this is a major old thread and I'm knocking dust for no more reason than to comment! LOL

BUT...I have to sympathize with anyone (me included) who has fallen under the spell of the LS4. I have driven both a Grand Prix GXP and a Monte SS and the sound plus the power is intoxicating. Sadly, neither car packs the sexy looks, inside or out, of the Bonneville. Every time I look under the hood I know full well the potential of the L36. I have seen them built and turbo'ed, and I've seen modded L67s and both engines can easily become tire-frying monster killers. However I recall reading where one of the chief engineers at Audi said that there is nothing more compelling than the sound of a naturally aspirated V-8, and I agree with him completely.

The roomy engine bay of the Bonneville almost seems to beg for the LS4 that has been shoe-horned into the Grand Prix, and the sound, torque and power would transform the car from sexy highway cruiser to some American version of a Jaguar XJ...the ever-potent iron fist inside the velvet glove (or nice tan leather! LOL)

Either way, had I the money and the means, value be cast to the wind, the end result would be one of those car GM should have built and didn't for whatever bean-counting reason.

They did build it, the right way. See my sig. They just didn't name it Bonneville, although they should have.