I'm Building a 1991 GSX

[Freerevving]

I pretty sure this has been covered before... I'm building a 1991 GSX
AND I would like some help from the members here. I don't think I absolutelyneed the help, as I'm an experienced shade-tree mechanic and tuner, but I'd like things to go smoother, quicker, and be more reliable-- especially since I'm new to building DSM's

I'm, so far, well-educated on what I need to get it together as I've been studying the car and the internet now, for about a month, before posting here. I should have a Haynes or the like by Sunday... but suprisingly the internet (and the Autozone website tech-book) has provided an amazing amount of information. So here's what I've got:

Base car: 1991 GS (clean title, no transmission)

Donor Car: 1992 GSX (no title, no engine, no ecu, no engine harness)

Extra parts: two non-turbo 4g63's. two GSX trannies. Ig turbo manifold, intake manifold, throttle body, side mount intercooler, stock internal wastegate turbo (no shaft play), bov, turbo coolant lines, boost controller and extra downpipe. I also have 1g turbo pistons and rings for the rebuild. I'm sure I'm forgetting something

ALL THE ABOVE CARS/PARTS were accquired for a total of $580

Things I need and don't have: 450cc injectors, Turbo MAF, Fed ECU, gasket set, bearing set, balance shaft elimination kit, oil lines (i think?)... no, I will not be running oil squirters until the 2nd engine's rebuild.

I have no idea where the turbo oil lines go, or weather I need to tap the oil pan. I would also like to run 8.5:1 compression... can this be accomplished by shaving the head? by how much (if there is clearance)?

I would love to get suggestions, opinions, and advice.

I also have the option of running the 92 front end... Need opinions on this also, because I'm split...

Thanks in advance, Mac

 

[mygsx2120]

Unfortunately, I don't think it's possible to swap an AWD transmission into a fwd 1g without tons of fabrication. It's not like on 2g cars.

As far as oil lines, you can take your feed line from your head. The return line needs to be tapped into the pan. Some people actually prefer to do this

I would look into using a 2g maf since you need to buy one anyways. It will save you trouble later.

If you want 8.5:1 compression, I would just buy some 2g pistons.

 

[SBR Joe]

Unfortunately, I don't think it's possible to swap an AWD transmission into a fwd 1g without tons of fabrication. It's not like on 2g cars.

Not unless you weld the center diff and run with no t case in FWD form...but who wants to do that.


Joe

 

[mygsx2120]

You will also need a headgasket for the rebuild, and might as well buy some ARP studs. Plus at least a new oil pump, if not water pump also.

I also have the option of running the 92 front end... Need opinions on this also, because I'm split..

Keep the pop ups.

 

[Freerevving]

If you want 8.5:1 compression, I would just buy some 2g pistons.

I'm triying to buy as little as possible... can the head be shaved?

Unfortunately, I don't think it's possible to swap an AWD transmission into a fwd 1g without tons of fabrication. ...

Not unless you weld the center diff and run with no t case in FWD form...but who wants to do that.

WHat kind of fabrication? I've been told everything will bolt up as long as I have the AWD tranny mounts

 

[Freerevving]

WHat kind of fabrication? I've been told everything will bolt up as long as I have the AWD tranny mounts

anyone?

 

[redyute1]

shaving the head will increase compression u might not want to do that,got a 93 not turbo ,slapped a turbo on it with 8 psi of boost and blew it thaught about all wheel drive conversion but it is a little fabrication that i am not willing to take on right now,i am a mechanic but not a welder

 

[Freerevving]

thanks I'm want to increase compression to 8.5:1-- the N/T block will have turbo pistons in it.. the only thing that will be different from the F/I 4g63 will be the lack of oil squirters.

I didn't mention: the GSX parts car will be delivered Sunday, so I don't have a reference to look at.

Can someone tell me what needs to be fabricated? Is it minor cutting/welding? what is required?

 

[Mikael SS]

thanks I'm want to increase compression to 8.5:1-- the N/T block will have turbo pistons in it.. the only thing that will be different from the F/I 4g63 will be the lack of oil squirters.

I didn't mention: the GSX parts car will be delivered Sunday, so I don't have a reference to look at.

Can someone tell me what needs to be fabricated? Is it minor cutting/welding? what is required?

that compression increase will do very little for helping spool, and not really worth it. You'll be able to put more boost on the stock compression pistons.

There are threads on the swap, search for it. It is not minor, and not worth the work. Lots of fabrication

Why not just use the AWD shell?

 

[Freerevving]

that compression increase will do very little for helping spool, and not really worth it. You'll be able to put more boost on the stock compression pistons.

There are threads on the swap, search for it. It is not minor, and not worth the work. Lots of fabrication

Why not just use the AWD shell?

supposedly problems with the title

 

[Freerevving]

Thanks to everyone who helped me realize this is more involved and what to search for in this forum and in the rest of the internet.

Being that fabrication is not a problem for me... southeast houston is completely industrial, almost everyone of my friends owns welding equipment, and I'm a machinist-apprentice by trade. This project is "go"

Being that no one on here has swapped a 1G rear end, I'm sure it's far less involved than people have exaggerated (and far more involved than I want to admit). Hopefully it's only cutting and welding, but if it requires more, then, OH WELL

Looks like I'll be the first one to document it on this Forum (if someone else has done this to a 1G, please send me the link... but I searched pretty well)

My main goal is keeping the cost below purchase price of a running GSX, and have enough parts left over to sell (and possibly pay for itself). Naysayers prepare to be amazed WTFWTFWTFWTF

I can't get enough of the beating a dead horse smily


I don't have a digital camera yet, but I'll be getting one/borrowing one for this project (and to sell my extra DSM/VW parts... need my garage back)

Thanks again everyone... Feel free to reply as I plan on posting progress and pictures very soon

P.S. there is still a chance that, in the future, I'll find an EXTREMELY cheap AWD shell that has a title

 

[CompuBob_TSi]

you should be able to swap in a AWD transmission.. but as what was previously stated, you will need to weld the center differential and/or get a Vicious Coupler Eliminator (VCE).. you will obviously not install the transfer case and you can just leave the output shaft spinning in the wind.

 

[VETTE_50_TH]

Search 1g awd into fwd. It can not be done without HEAVY modification to the rear. There is no cutout in the car for a driveshaft. Get on teh ground and look down to the rear of the car of both of them. There is a lot that is different. The exhaust, driveshaft, rear end, subframe, gas tank. It would not be feasible. Just letting you know. I read a thread about someone who swore up and down he was going to do it. It never happened.

James

 

[mygsx2120]

Naysayers prepare to be amazed

We are not saying it is impossible, just a waste of time and money. The only shop that I know of that has completed this was RRE, and they said they would never do it again, period! And they have all the resources of a full on shop.

Not to sound rude, but what is the point of asking for advice and when we give it, you just ignore us and do what you planned on anyway?

I'm pullin' for ya though, good luck.

 

[Mikael SS]

supposedly problems with the title

use the FWD title.

Instead of taking 99% of the parts off the GS, just move the 1% from the GS to the GSX. Its not like you stole the cars, right?

 

[My1GLaser]

I have done 2 FULL ground up rebuilds in the past year. 90 Laser and 92 GSX. Before I get started, why dont you just swap the VIN off the dash from the 91 to the 92? That's what I would do. They are both 1gb right? No popup headlights. Most of the parts that could have VINs are engine & tranny, maybe ECU...only about half of us are running the original ones if we have done any kind of major rebuild, and broken a lot of sh_t.

Moving on. I had the Laser stripped down to the body. No interior, harness, no front subframe and no rear end AT ALL, completely stripped engine bay. I painted everything but the exterior body panels and sprayed the interior with rubberized undercoating. I am doing a more conservative rebuild on the GSX, but the entire front end was stripped out and I have spent many hours under the car. The rear end is totally different. Rear diff support, different trailing arm connections, an actual subframe with body mounts, totally different gas tank, different shocks & springs (not sure about the towers but I can look later) different exhaust from the DP back, there is no "channel" for the drive shaft. I am sure the actual tranny will bolt up painlessly though. If you have a frame shop then it would be more feasible to get the rear aligned properly after the fabrication. There is a lot of room for error in getting the alignment correct so it doesn't pull like a bi*** and chew thru tires like a wildabeast.

I have welded and fabricated for 12 years on railcars. Unless you have 6 months and a lot of patience I would not tackle it. (unless you don't have a job or go to school or something) Except for a lift, I have every tool imaginable for fabwork and I wouldn't want the project. Don't get me wrong, it can be done. I could do it and if you are determined enough then I am sure you could too. But what is the point if you have other chassis sitting there.

If thats the project you are looking for then have at it. But if you want to drive your car soon and save yourself a huge headache, then why not just build a dunebuggy and throw a 4G63 in it or something? That would get the fabrication bug out of your system. I hope the best for your project!

 

[My1GLaser]

As for the compression, I went with 9:1. I am about to go out and crank the car for the first time today so I don't have any feedback on how it acts compared to the 7.8:1. I am confident that I made the right choice. I like the idea of making the same power with less boost. I plan to road race and autocross, with the occasional 1/4 mile run. I have an EVO 16g that will be great for the first 2 and I can probably run 11s with my mods. So going with the higher CR was perfect for me, but it depends on your goals. If you get into large turbos running high boost then tuning around knock can be a bi*** without running racegas all the time, which I didn't want to do.

No you can't shave the head to raise your CR. Well, it will raise marginally, .1 or .2 or something. But you want there to be a proper quench area when building the motor. Ideally .045 (+ or - .005) b/w the top of the piston and the bottom of the head. If the pistons sit in the cyl then you might want a stock HG. If they are .010 out of the hole (like mine) then you will want a thicker HG. I went with a .054 Mitsu MLS HG. I have a spreadsheet for calculating CR if you want me to email it to you. I can't upload it for some reason.

Oh, and depending on the mileage on the block you will probably have to go .020 over. Mine looked fine, but had a taper that I wasn't comfortable with. You really have to measure to be certain. Or you could find out like me. I was setting ring end gaps and they were .018, 2" down in the block, but at the top right under the ridge it was like .032.

Josh

 

[Freerevving]

We are not saying it is impossible, just a waste of time and money. The only shop that I know of that has completed this was RRE, and they said they would never do it again, period! And they have all the resources of a full on shop.

Not to sound rude, but what is the point of asking for advice and when we give it, you just ignore us and do what you planned on anyway?

I'm pullin' for ya though, good luck.

you're right... that part sounds rude, but no offense taken. Maybe I wasn't specific as to what kind of advice I wanted... but I was hoping for advice on how to do it and what it would require. I definitely wasn't looking for (what I hear 2 million other people say in other threads, who by the way, have never attempted it) "just don't do it it's too hard and to expensive". TOO HARD? maybe TOO EXPENSIVE? $580 is not too expensive.

Please, if you don't have any input "you just ignore us" doesn't help me, especially since it's not true. It's up to the individual to decide which advice he takes and which he ignores. Am I ignoring anyone? I already said if I find a cheap enough AWD shell I'm buying it... But so far I can't find one for under $1000 (shooting for $500)

thanks for pulling for me

I have done 2 FULL ground up rebuilds in the past year. 90 Laser and 92 GSX. Before I get started, why dont you just swap the VIN off the dash from the 91 to the 92?

Funny you mention this. I Really considered it yesterday, so I asked around. One person said is it's not safe to do. For one, (sounds corny) I'm not sure I could live with myself... two, the colors don't match and there in a VIN with the color on the inside of the door.. and I'm told in other mystery spots... please if you have any more ideas on this I can definitely use them ... you might save me from the "fun" part of my project

Moving on. I had the Laser stripped down to the body. No interior, harness, no front subframe and no rear end AT ALL, completely stripped engine bay. I painted everything but the exterior body panels and sprayed the interior with rubberized undercoating. I am doing a more conservative rebuild on the GSX, but the entire front end was stripped out and I have spent many hours under the car. The rear end is totally different. Rear diff support, different trailing arm connections, an actual subframe with body mounts, totally different gas tank, different shocks & springs (not sure about the towers but I can look later) different exhaust from the DP back, there is no "channel" for the drive shaft. I am sure the actual tranny will bolt up painlessly though. If you have a frame shop then it would be more feasible to get the rear aligned properly after the fabrication. There is a lot of room for error in getting the alignment correct so it doesn't pull like a bi*** and chew thru tires like a wildabeast.

I'm really glad you posted... everyone has been helpful but you have been the most.

I have all the different parts that I need (exhaust and rear end, tank, etc, etc). On my 1991 I do see a channel Exhaust sits down the middle of it... Problem is (I mentioned before) that the GSX arrives Sunday (tomorrow) and I don't have the reference. This explains (possibly the only explanation?) why this project woul not be worthwhile AND EVEN THOUGH I still want to compare for myself, I believe what you have told me. You obviously have had the experience with it, and thanks again for telling me a reasonable explanation of the difficulty.

No you can't shave the head to raise your CR. Well, it will raise marginally, .1 or .2 or something. But you want there to be a proper quench area when building the motor. Ideally .045 (+ or - .005) b/w the top of the piston and the bottom of the head. If the pistons sit in the cyl then you might want a stock HG. If they are .010 out of the hole (like mine) then you will want a thicker HG. I went with a .054 Mitsu MLS HG. I have a spreadsheet for calculating CR if you want me to email it to you. I can't upload it for some reason.
Josh

This answers my question... Shaving the head on this engine would create a risk of the valves hitting. BTW we raised the compression on our 9A's (2.0L 16V) from 10.6:1 to 12:1 by shaving the head and using one adjustable cam gear. Head chambers were 45cc's and cylinder bore was 82.5mm. I figured that with the angle of the valves (on the 4g63) and the small chambers I might have problems shaving the head. thanks for the insight

REALLY glad you all posted You have all bveen A Great Help

I'll get back to this tomorrow after I get the other car over here.

 

[mavisky]

Look, I was one of the first people to ever attempt to swap a fwd turbo engine and drivetrain into a non-turbo chassis and the first to document it on the internet as far as I could find.

I would want nothing to do with this project and trust me I've researched everything needed to make this happen as my car is still a fwd. The front subframe is completely different, the rear subframe is even more different, and the entire floorboard from the firewall back is different.

I'm sure it could be done by someone with either severely impressive skills and a full shop or by some unexperienced kid, but the results are going to be totally different. You'd actually be better off trying to use a solid rear end out of another vehicle and matching the gear ratios than trying to hook fabricate all the IRS's rear mounting points.

I implore you to simply go out and look underneath the vehicle and tell me what differences you see in the rear area alone. There are many as you'll come to find out. On a 2g they used independent rear suspension on both the awd's and the fwds with near identical mounting points so all you have to do is bolt up the awd parts and you're ready to go for the most part. That is not the case at all with the 1g's. When RRE did a few of these back in the day, it was for rally drivers and they were having trouble tracking down 1g awd's to go racing in so for something like $5000 RRE was converting fwd's over. It didn't make financial sense then and it doesn't now either.

Buy a turbo engine and wiring harness for about $1000 of somebody, go to the DMV and apply for a title for the awd and get it up and running. Save the fwd nt to drive while you're working on getting the awd ready.

 

[mavisky]

Also for quick reference go to Autozone and open up the 90-94 dsm Haynes manual they have and look at the pictures in the first chapter to see the very different rear suspension setups on the two cars.

 

[Freerevving]

Look, I was one of the first people to ever attempt to swap a fwd turbo engine and drivetrain into a non-turbo chassis and the first to document it on the internet as far as I could find.

I would want nothing to do with this project and trust me I've researched everything needed to make this happen as my car is still a fwd. The front subframe is completely different, the rear subframe is even more different, and the entire floorboard from the firewall back is different.

I'm sure it could be done by someone with either severely impressive skills and a full shop or by some unexperienced kid, but the results are going to be totally different. You'd actually be better off trying to use a solid rear end out of another vehicle and matching the gear ratios than trying to hook fabricate all the IRS's rear mounting points.

I implore you to simply go out and look underneath the vehicle and tell me what differences you see in the rear area alone. There are many as you'll come to find out. On a 2g they used independent rear suspension on both the awd's and the fwds with near identical mounting points so all you have to do is bolt up the awd parts and you're ready to go for the most part. That is not the case at all with the 1g's. When RRE did a few of these back in the day, it was for rally drivers and they were having trouble tracking down 1g awd's to go racing in so for something like $5000 RRE was converting fwd's over. It didn't make financial sense then and it doesn't now either.

Buy a turbo engine and wiring harness for about $1000 of somebody, go to the DMV and apply for a title for the awd and get it up and running. Save the fwd nt to drive while you're working on getting the awd ready.

I hope this sounds somewhat humble: I don't need to buy any of that... And there is a bank lien against the title for $2000... they don't want to settle for any less than that... No Title will be aquired for that shell

I am fully aware that the suspension Is totally different... The main difference is the upper mounting point. You talk about Spending $1000 like it were a pack of cigarettes.... NOT THE CASE. This whole project will cost me under $1000 ($580) PLEASE read that the car will be delivered tomorrow, so I cannot directly compare until then

I just got off the phone with an 1G AWD enthusiast, who has built close to 7 AWD's (not from a FWD) He claim that the upper suspenion mounting point will need to be ground off the old chassis and re-welded on the new chassis. And the center diff will need the same operation... AND all the unbolt-able parts (INCLUDING TANK) will need to be swapped over. EASY! (well for me)... He further stated that, other than that, the FWD and AWD bare shells are identical

ALL PARTS NEEDED ARE ON THE DONOR "SHELL" which is just missing the engine and I have one... again ALL THE PARTS I HAVE ARE INCLUDED IN MY SPENDING PRICE OF $580 cool huh?

please be optimistic about this

 

[VETTE_50_TH]

Its hard to be optimistic when the best shops in the world dont want to do it, and the only one to prove it was done RRE, will never do it again. You have fun with that, you provide pictures and documentation, then the naysayers will take back what they said, esp for the amount of money you want to put into it.

James

 

[My1GLaser]

Oh sh_t, Mavisky is totally right about the front end. I was so focused on the difference in the rear end of the car that I forgot the front is way different too. The steering rack subframe is basically the same from what I can tell, but that is it.

Instead of the one support that runs under the motor and bolts to the radiator support there are two on either side of center, and they do not bolt to the radiator support. There is another crossbrace that goes from one side of the unibody "frame" to the other side right behind the rad support. I will look in the morning to see if all the body mounting points are there on my FWD engine bay so you could swap over the AWD parts you have. But I guess you will have the car tomorrow for reference. Either way, it looks like its gonna be a bi***. Good luck with whatever you choose. If you got the time to kill then what the hell. Plus with enough ambition and fabrication skills, maybe you will swap a 4G63 into a car that hasn't been done before. You might be a little crazy, but you got guts (or stupidity. They have very similar characteristics...haha, jk)

BTW, thats a hell of a CR change by shaving the head. I just know that you can't get away with much on these cars. The FSM actually only allows .008 to be removed from the block & head combined. You can get around that limit with a MLS gasket of course, but the CR goes right back down. The stock head is 47cc, but mine is 44.8 after OS valves and resurfacing. Strangely, my Wiseco pistons were dished 11cc instead of 10cc, so that helped lower my CR back down some. I was trying to shoot for exactly 9:1.

 

[mygsx2120]

please be optimistic about this

Over 50,000 members and no one has did it yet. Please take pics and do a writeup so others can follow your path. People sell 1g nt like they are the plague, if you pull it off, this will probably be my next project.

ALL PARTS NEEDED ARE ON THE DONOR "SHELL" which is just missing the engine and I have one... again ALL THE PARTS I HAVE ARE INCLUDED IN MY SPENDING PRICE OF $580 cool huh?

Aren't you building a motor? That will cost at least $1,000 right there. Even if you assemble it, it will still cost at least $500. Maybe ohio shops are more expensive than ones in Texas.

 

[slowgsr]

Funny you mention this. I Really considered it yesterday, so I asked around. One person said is it's not safe to do. For one, (sounds corny) I'm not sure I could live with myself... two, the colors don't match and there in a VIN with the color on the inside of the door.. and I'm told in other mystery spots... please if you have any more ideas on this I can definitely use them ... you might save me from the "fun" part of my project

:

Common dude be a free thinker!

All you need to do is swap the vin's, the one on the door jam, is it a rivited tag, if so just removed and re-rivit, or if its a sticker peel her off.

As far the the colors not matching.. thats easy too, just go to the ministry tell them you painted it, easy as pie, they will change the color on the ownership.

You wont get caught.. Its next to impossible, i plan to find another red 1g as a winter car, and when winter comes, just pull the plates from my reg 1g DD and put them on the winter car, same year, same color.. when you get pulled over they dont ever cross reference vins! This way.. no insurance transfer or plate transfer or anything, plus if my DD breaks i can just drive the beater till shes fixed.

Its not like the car is stolen and your doing anything really wrong.