Build overview, critique, and ideas LQ4/4L80E into a RWD Conversion
02-12-2010, 06:45 PM
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Build overview, critique, and ideas LQ4/4L80E into a RWD Conversion Alright, so here is the story. This thread is mostly to have you guys go over my research, and see if my build plan is airtight.
The Car:
1998 Pontiac Grand Prix GTP. It currently has a mild 3.4 S/C pulley setup on it. It's a fun car, but it's just not what I want to have. I like the idea of a big V8, RWD sedan. And I don't like the options that are out there. The G8 is a lovely machine, but I don't care for the styling all that much. So, the obvious answer is to make my car (which I love the styling) into the car I want.
The Conversion:
Using a 4th gen Camaro K-member in the front, it'll only take some minor fab to get it mounted up right, and the only custom piece in the front suspension will be the control arms and tie rods. In the middle, the floor pan only needs some basic modification to accommodate the driveshaft and trans hump. I already have some custom subframe connectors in the rocker panels (since they were already cut open to take care of some rust) that I want to tie a roll cage into. In the rear, The whole G8 rear subframe looks like it'll be a near perfect fit for the rear subframe already there, with just some minor fab to make some mounting points and some spring perches for the G8's strut/springs. At that point I might also do some mini-tubs. As a note, this part I'm confident in and don't really need much advice here.
The Drivetrain:
My plan is to drop in an LQ4 with a 4L80e behind it. It will need a car intake and acc. drive to fit under my hood. But I want to go with a supercharger down the road, with a goal of about 500 RWHP. So that's why I thought the low compression LQ4 would be a good bet. The rear end would be the IRS G8 GT or GXP rear end. Hoping to make enough room to run 315 rubber in the back.
The Goals:
When finished I want to have a summer Daily Driver that can go to the track and run low 12's or high 11's in street trim, full weight. Target weight is 3999lbs or less. I also want it to handle the best possible. I want a good, well rounded car, that can still seat four people in reasonable comfort. My project theme is "The baddest Sedan GM could have made from the factory." Essentially I'm making a CTS-V ten years early.
My Concerns:
1. What do I do about running a driveshaft? The rear diff. will be stationary, and I'm planning on solid mounting the motor. So I think from what I've read, I should slightly offset the motor so that the u-joints in the driveline have full range of motion.
2. What are the "best"choices for a starting point with an LS motor? I know I want a 6 liter motor. But other than that, I'm open to suggestion. I know I want it to be supercharged later on.
3. I'm sure I have others, but I can't think of them at the moment.
Thanks for looking this over guys. I'll probably be starting the tear down and parts buying summer or fall of this year, if things go well. Any and all input (other than "you're stupid, just buy a GTO/camaro/G8/etc.") is fully welcome.
The Car:
1998 Pontiac Grand Prix GTP. It currently has a mild 3.4 S/C pulley setup on it. It's a fun car, but it's just not what I want to have. I like the idea of a big V8, RWD sedan. And I don't like the options that are out there. The G8 is a lovely machine, but I don't care for the styling all that much. So, the obvious answer is to make my car (which I love the styling) into the car I want.
The Conversion:
Using a 4th gen Camaro K-member in the front, it'll only take some minor fab to get it mounted up right, and the only custom piece in the front suspension will be the control arms and tie rods. In the middle, the floor pan only needs some basic modification to accommodate the driveshaft and trans hump. I already have some custom subframe connectors in the rocker panels (since they were already cut open to take care of some rust) that I want to tie a roll cage into. In the rear, The whole G8 rear subframe looks like it'll be a near perfect fit for the rear subframe already there, with just some minor fab to make some mounting points and some spring perches for the G8's strut/springs. At that point I might also do some mini-tubs. As a note, this part I'm confident in and don't really need much advice here.
The Drivetrain:
My plan is to drop in an LQ4 with a 4L80e behind it. It will need a car intake and acc. drive to fit under my hood. But I want to go with a supercharger down the road, with a goal of about 500 RWHP. So that's why I thought the low compression LQ4 would be a good bet. The rear end would be the IRS G8 GT or GXP rear end. Hoping to make enough room to run 315 rubber in the back.
The Goals:
When finished I want to have a summer Daily Driver that can go to the track and run low 12's or high 11's in street trim, full weight. Target weight is 3999lbs or less. I also want it to handle the best possible. I want a good, well rounded car, that can still seat four people in reasonable comfort. My project theme is "The baddest Sedan GM could have made from the factory." Essentially I'm making a CTS-V ten years early.
My Concerns:
1. What do I do about running a driveshaft? The rear diff. will be stationary, and I'm planning on solid mounting the motor. So I think from what I've read, I should slightly offset the motor so that the u-joints in the driveline have full range of motion.
2. What are the "best"choices for a starting point with an LS motor? I know I want a 6 liter motor. But other than that, I'm open to suggestion. I know I want it to be supercharged later on.
3. I'm sure I have others, but I can't think of them at the moment.
Thanks for looking this over guys. I'll probably be starting the tear down and parts buying summer or fall of this year, if things go well. Any and all input (other than "you're stupid, just buy a GTO/camaro/G8/etc.") is fully welcome.
02-12-2010, 07:20 PM
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lq4 if you want to go boost, lower compression ratio, or the LQ9 if your looking for high compression and a tad bit more power. This is if your just going stock for stock that is.
02-13-2010, 01:45 AM
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To stick to my theme for the project, I would like to stay as much with GM factory parts as possible. So no tricked out heads, or forged motor, or wild cams. I'm willing to divert a little for the necessities, such as fuel parts, and the blower setup, and parts that need to be custom obviously. But in the main, I want you to think it rolled out of GM just like it is. I would be willing to swap heads if one set would apply better to my app than the (317's I think?) ones that come on the LQ4.
One question I should already know the answer to, what's the weight savings going with an alum block over an iron one? It runs in my mind it's only like 70lbs, confirm? Whats an LQ4 and 4l80e going to weigh in at, approx?
Also, would you say the Iron block has more longevity than an alum one? I.E. it could be bored over more times.
Another question I have is about alternators. I belive you have to run car accs. to have a car intake on the motor, right? Including moving the alt? Because I really like the idea of Summit's 260 amp(I think thats right) alt for the truck, since I have a lot of electronics in my car. Would I be able to mount that alt in the car location? Or would I be making custom brackets?
Another question, will a stock 4l80e handle a blown lq4??
Does anyone here use a stand-alone controller for their trans? I'm pretty interested in TCI's product with the paddle shifters.
That's all for now. Thanks guys!
One question I should already know the answer to, what's the weight savings going with an alum block over an iron one? It runs in my mind it's only like 70lbs, confirm? Whats an LQ4 and 4l80e going to weigh in at, approx?
Also, would you say the Iron block has more longevity than an alum one? I.E. it could be bored over more times.
Another question I have is about alternators. I belive you have to run car accs. to have a car intake on the motor, right? Including moving the alt? Because I really like the idea of Summit's 260 amp(I think thats right) alt for the truck, since I have a lot of electronics in my car. Would I be able to mount that alt in the car location? Or would I be making custom brackets?
Another question, will a stock 4l80e handle a blown lq4??
Does anyone here use a stand-alone controller for their trans? I'm pretty interested in TCI's product with the paddle shifters.
That's all for now. Thanks guys!
02-13-2010, 02:54 AM
#4
Not to be a downer but I guarantee by the questions you have raised this is going to be a larger project than you believe it will be. I have to commend you for heading in the right direction by creating a plan. My suggestion is to find a Grand Prix with a dead engine or transmission and cut that one up. This gives you something to drive and you don't kill your favorite car.
None of your interior (seats, console, etc.) are going to work without modification. A transmission tunnel will have to be fabricated along with an engine cradle, engine mounts, transmission mount, rear axle, front and rear suspension, etc. Another thought is if you haven't done something like this you are going to spend a LOT of time measuring, remeasuring, cutting, welding, fabricating and fitting.
As far as a non moving differential with IRS, MN12 chassis (90's) Thunderbird / Cougars, Lincoln Mark VIII's, GTO's, G8's, Subaru's, IRS Explorers and escapes, etc. are all examples of this. Having a differential that does not move with the wheels isn't a problem but it makes getting your drive line angles right a bit more critical. The best example I have found about setting drive line angles is located here.
5.3 engines are much more common than 6 liters and thus are cheaper. If you aren't pulling it apart, who cares what the displacement is? Honestly, mod for mod the final output power will be within a few HP of each other.
Hood and oil pan / steering clearance will be an issue with this setup. Grand Prix / Monte Carlo ? Lumina chassis cars are rear steer which puts the sump on the pan where the steering rack is. A GTO pan MAY work in this situation. Check the stickies for information on oil pan sizes and shapes. A car intake is necessary for this to work, this means the front accessory drive will have to be modified for hood and intake manifold clearance.
Something to think about is buying a wrecked V8 Camaro or something and cutting the body off, then using the chassis as the chassis for the Grand Prix. Look for a guy called Civette on here. He made a Corvette powered Civic by using the full chassis from the Corvette and trimming the Civic to fit it. He basically "skinned" it as a Civic.
Again, not trying to be a downer but unless you have mad fab skills and a large supply of fabrication tools and time handy this will be a BIG undertaking. I've thought about it for a long time but been too busy and have far too many projects to acquire the additional cars and parts for it to happen.
I do wish you lots of luck. Somewhere else to look for info about chassis building and such is Pro-Touring.com. There are many of us afflicted (infected?) with the car disease and the forum is more about the type of fabrication necessary for this type of thing.
Good luck and keep us posted. I would love to see it.
None of your interior (seats, console, etc.) are going to work without modification. A transmission tunnel will have to be fabricated along with an engine cradle, engine mounts, transmission mount, rear axle, front and rear suspension, etc. Another thought is if you haven't done something like this you are going to spend a LOT of time measuring, remeasuring, cutting, welding, fabricating and fitting.
As far as a non moving differential with IRS, MN12 chassis (90's) Thunderbird / Cougars, Lincoln Mark VIII's, GTO's, G8's, Subaru's, IRS Explorers and escapes, etc. are all examples of this. Having a differential that does not move with the wheels isn't a problem but it makes getting your drive line angles right a bit more critical. The best example I have found about setting drive line angles is located here.
5.3 engines are much more common than 6 liters and thus are cheaper. If you aren't pulling it apart, who cares what the displacement is? Honestly, mod for mod the final output power will be within a few HP of each other.
Hood and oil pan / steering clearance will be an issue with this setup. Grand Prix / Monte Carlo ? Lumina chassis cars are rear steer which puts the sump on the pan where the steering rack is. A GTO pan MAY work in this situation. Check the stickies for information on oil pan sizes and shapes. A car intake is necessary for this to work, this means the front accessory drive will have to be modified for hood and intake manifold clearance.
Something to think about is buying a wrecked V8 Camaro or something and cutting the body off, then using the chassis as the chassis for the Grand Prix. Look for a guy called Civette on here. He made a Corvette powered Civic by using the full chassis from the Corvette and trimming the Civic to fit it. He basically "skinned" it as a Civic.
Again, not trying to be a downer but unless you have mad fab skills and a large supply of fabrication tools and time handy this will be a BIG undertaking. I've thought about it for a long time but been too busy and have far too many projects to acquire the additional cars and parts for it to happen.
I do wish you lots of luck. Somewhere else to look for info about chassis building and such is Pro-Touring.com. There are many of us afflicted (infected?) with the car disease and the forum is more about the type of fabrication necessary for this type of thing.
Good luck and keep us posted. I would love to see it.
02-13-2010, 03:25 AM
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Okay, to start out, thank you for your reply. It shows me people are interested in my project. But, to get into it, I am not asking for help on how to pull off my conversion. I already have two Grand Prix donor cars and my DD, so I'm set there. You answered my driveshaft question about how to set it up. I did know it wouldn't be a problem to run it, I just knew some special consideration on the angles involved would be required. As for the front suspension, I outlined what I'll be doing for that in my first post. I'm following in the footsteps of a friend of mine who has already completed this exact swap, I'm just improving on his design in some areas. Simply switching sides on the spindles puts the steering in the front. I know (and have pictures of) what exactly needs done to the interior of the car. The factory seat munting locations will be just fine.
On the 6.0 issue, I just have my heart set on sticking a GTO 6.0 badge on my trunk (it will be the only hint that it's not a factory car on the outside) and I don't want to deviate. I'm pretty picky about some things.
I guess that's all I have to say. I'll just end this post by stating again that I know precisely what I'm getting into, and what I'm going to do for the conversion itself. I just wanted a few questions answered about the drivetrain I plan on using. I can remove the rest of the details if they become confusing, I just wanted to provide full background info.
I'm not trying to be snappy, just wanted to clear up that I know what I'm about, and what I can and can't handle.
On the 6.0 issue, I just have my heart set on sticking a GTO 6.0 badge on my trunk (it will be the only hint that it's not a factory car on the outside) and I don't want to deviate. I'm pretty picky about some things.
I guess that's all I have to say. I'll just end this post by stating again that I know precisely what I'm getting into, and what I'm going to do for the conversion itself. I just wanted a few questions answered about the drivetrain I plan on using. I can remove the rest of the details if they become confusing, I just wanted to provide full background info.
I'm not trying to be snappy, just wanted to clear up that I know what I'm about, and what I can and can't handle.
02-13-2010, 11:34 PM
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02-14-2010, 03:23 PM
#8
Been here and done that.
Do yourself a favor and try not to re-engineer stuff that already works. I kept the stock front subframe and used a gto pan/pickup. You will need to drop the rack and use a bumpsteer kit.
The tunnel will need to be modified up to the rear seat as eaton_rice has done. Using an 8.8 IRS and subframe from one of vehicles listed above is your best bet. one of the options listed has the right width to start with and will net a comparable bolt pattern/offset. This is the route I chose.
The tank will need to be relocated behind the axle using either a raised tank or fuel cell.
The camaro front clip is more work than is necessary to make this work. I was able to keep all the front end stock GTP which keeps your parts list in the glove compartment just a little shorter.
Be sure to do the C5/C6/F-Body brake upgrade.
Do yourself a favor and try not to re-engineer stuff that already works. I kept the stock front subframe and used a gto pan/pickup. You will need to drop the rack and use a bumpsteer kit.
The tunnel will need to be modified up to the rear seat as eaton_rice has done. Using an 8.8 IRS and subframe from one of vehicles listed above is your best bet. one of the options listed has the right width to start with and will net a comparable bolt pattern/offset. This is the route I chose.
The tank will need to be relocated behind the axle using either a raised tank or fuel cell.
The camaro front clip is more work than is necessary to make this work. I was able to keep all the front end stock GTP which keeps your parts list in the glove compartment just a little shorter.
Be sure to do the C5/C6/F-Body brake upgrade.
02-14-2010, 06:53 PM
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I already have F-body brakes, all hand polished to a mirror finish. I guess I need to post my engine questions in another section, as I don't need any advice for the conversion itself. One of the reason I am going with the camaro front end is because I am going to relocate the mount points and make a long-arm setup for the front suspension. I've got the CAR completely figured out. I wanted DRIVETRAIN advice.
02-14-2010, 08:15 PM
#10
yup. Post elsewhere I suppose.
You have already been given good advice:
I'm sorry that you have everything all figured out and everyone else, even those who have done your swap or similar ones like it can't offer useful information because they just don't know like you do!
Cheers and good luck.
You have already been given good advice:
5.3 engines are much more common than 6 liters and thus are cheaper. If you aren't pulling it apart, who cares what the displacement is? Honestly, mod for mod the final output power will be within a few HP of each other.
Cheers and good luck.
02-17-2010, 06:01 AM
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Well, I've been thinking on it a lot, and it seems to me that the smartest idea is to go with an LM7 engine.... I really wanted to have that 6.0 badge, but saving almost a thousand dollars just makes sense to me. That's all my steering gear, for example. I apologize for being hard-headed. If anyone else would like to offer any comments, I'd love to hear them. On ANY aspect. Never know, maybe I'll get a good idea I haven't thought of yet.
On a side note, I've been toying with some drawings on paper and it seems like for what I want, maybe a custom K-member is the way to go.
On a side note, I've been toying with some drawings on paper and it seems like for what I want, maybe a custom K-member is the way to go.
02-17-2010, 06:34 AM
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How much are you spending on this swap? I mean if it comes down to it... just get a G8 GT..... there not that expensive... Im looking one to replace my GTP..
02-17-2010, 07:10 AM
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I don't like the styling of the G8. Too boxy. I'm looking to come in under $10k all told, my budget is about 50/50 drivetrain and other upgrades at the same time (like some frame stiffening, some interior stuff). I'd be willing to do it for anything under 20k though really. I do love this car, in many ways. And yes, I know there's no resale value in any of this. When I get it completely done to my liking, I'll put it through a complete nuts and bolts restoration and retire it to "Sundays Only". I plan to leave this car to my children one day.
02-17-2010, 04:01 PM
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Actually, here's how mine looks. And I'm not done with the appearance department yet.
But yes, I would. I don't like the sharp corners of the G8, and the interior just feels... off to me. I've been in several, and I just don't care for them. Plus, I'd detest a car I didn't have to work on. I remind you, this isn't my DD. It's my hobby car.
So anyways, I was thinking, that the Corvette supercharger kits with the angled down TB opening would help me out with hood clearance.
But yes, I would. I don't like the sharp corners of the G8, and the interior just feels... off to me. I've been in several, and I just don't care for them. Plus, I'd detest a car I didn't have to work on. I remind you, this isn't my DD. It's my hobby car.
So anyways, I was thinking, that the Corvette supercharger kits with the angled down TB opening would help me out with hood clearance.
