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Opeler
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Discussion Starter #1
I've seen lots of references to swapping nissan SR20DET into the GT but there never seems to be any pictures or documentation to go with it. I tried doing a search but all I came up with was a lot of conversations referring to the SR20. BuildinGT4Race said that he was installing the SR20DET in his post dated 3-24-2003 and DanOmyte said he was installing another turbocharged nissan engine (the CA18ET) in his post dated 5-30-2005. So I would image by now some one has tackled the obstacles of the wide SR20 manifolds and long transmission. If you've done it, please share your knowledge. I'm sure that I'm not the only one that is interested. I'll be starting the swap within the next month or so. I already have the engine, tranny, ecu, etc. I just can't start it till I finish building the VW bug for my wife. (luckily that is almost done.
 

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You might want to have a read of what it takes to actually transplant another motor into a GT. Seems that somebody in the San Diego area has kinda been all over this for a few days. A search tip would be for "willit?" or you could probably just go over and have a chat about your ideas in person. I hope that helps
 

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Living in the past
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motor swaps

With all the folks that want to rip out the drive train of a GT and replace it with what ever from a 3 cyl. Geo Metro to a Allison Aircraft engine, it looks like some enterprising young man (or lady) would have made up some molds and came up with a kit car for the folks that want the Opel GT "look" and not the rest of the "antique" trappings that go with it. I,and more than likely several hundred other GT owners, have fielded the statement, "that would sure be neat with a small block in it", well it is neat with a well prepared "big block" Opel engine in it. If a kit car was available then the rest of us would not have to search far and wide for a GT sitting in some dusty corner abandon after the owner finds out how much work it will take to make the "project" into a reality. Serveral people have done very well with Cobra's356's etc. so why not an Opel GT kit car. It would free up and put back into use a lot of GT parts and get rid of a lot of rusty sheet metal. JMTCW
 

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It is also pretty easy to bore and stroke what you got. Only about $800 to to make the bottom end, and you can decide how far you want to go with the top end. Guaranteed to fit too. Add a 5 Speed and pour in some fun. Electronic fuel injection is also available just use the Megasquirt brain box. Move the radiator forward and you can install a supercharger ore turbo, you'll need forged pistons though.

So it's quite easy to get a smoking fat GT by just using whats inside her. It's up to you to let it out.:)
 

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Opeler
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369 Posts
Discussion Starter #5
It's true that you can get quite a bit of power out of building an opel 1.9 and I've always liked the design of the opel engine but I started adding up what I wanted to do and decided that I'd go with an engine already built for the power. Last I checked a set of opel pistons were around $400 I can only imagine what forged would cost. The Getrag opel 5spd is up around $1k used, used opel fuel injection is what about another $500 - $1k and then throw on a turbocharger which you could probably do for $400-$500 if you use a used turbo from a nissan or subaru. So now you'd be close to $3k into it plus all the odds and ends. Or I could squeeze an SR20 that is already putting out plenty of power into it and is made to last a couple hundred thousand miles. I think going for a ride in my cousin's sickenly fast WRX powered 56' Bug was what finally got me to go for the swap. I picked up a SR20DET from a kid who had it in a 240sx. For $700 he let me take whatever I wanted so I got the engine, trans, ecu, wiring harness, intercooler and piping, radiator, drive shaft, clutch master & slave cylinders, and the electronic gage cluster. Now I know it will cost more than I think to do the swap but I'm sure it will still be less than building a comparable opel engine and trans set up.
 

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I remember looking at a SR20DET engine and tranny at a shop early on after getting my GT and thinking it would be a great swap. Lots of unstressed power, light weight, aftermarket support. However, if memory serves me correctly, it was a very tall engine and you would have to build a new front cross member to try to get it low enough to clear a hood...even a modified hood. Now that you have it, take some time with a tape measure and figure it all out. Lets face it, you can do anything with enough time and $$$ and if done CORRECTLY, it would make a killer swap.

Good luck!
Jc
 

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I don't know of anyone who has made this swap yet...or at least has admitted to having attempted it. I agree, the SR20 is a great engine other than having a propensity to spin bearings and throw rods out the side of the block!

We spoke a bit about the height issues here.

But that was just a normal SR20DE, with the DET the turbo and manifolding will be protruding into the footwell area and the area near the steering column.
A custom hood or scoop will likely be necessary to clear the front of the engine.
You'll need a different rear axle, since it is not only weak, but the length of the Silvia transmission is such that the torque tube can't be used...you need a straight driveshaft and a different axle arrangement with associated suspension link changes. All custom fabricated of course. If you decide to use the 240SX IRS, keep in mind it is much larger than the Opel axle so it will either require massive surgery to fit or you'll need to widen the body with fender flares.
The engine crossmember will have to be reworked of course, in order to mount the new engine.
You'll need a better front suspension to handle the power...the stock suspension is barely adequate for 90 hp, so making it handle 250 hp is asking a lot!
Don't forget brakes too, you'd cook the stockers with 2-3 stops from 100 mph. I'm talking complete fade...no brakes.
The biggest fitment issue is probably going to be cooling. SR20DE's make a lot of heat, and are prone to overheating and damage when revved hard (not good with an aluminum block!). The SR20DET makes even more heat, so consider an oil cooler mandatory and a large radiator as part of the equation. Trouble is, there's not much room to fit the bigger radiator without some surgery to the car, so add in a bunch of time and the cost of a good radiator and a high-mounted surge tank (to avoid air pockets which will damage the head). Add to this the fact that you'll need to make room for an intercooler up front, which will restrict the already limited airflow to the radiator and to the engine itself for cooling.

So, it's definitely a do-able proposition, but it must be approached with a definitive plan in your head rather than a 'cut this, cut that' attitude in order for it to succeed. Good luck with the endeavor if you decide to install the engine, it's one of the few engines I'd consider swapping into an Opel myself.

Bob
 

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Opeler
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Discussion Starter #8
Thanks for all of the suggestions Bob.

The SR20 isn't really that much taller than the opel 1.9. What makes it tricky is that the Opel is tall in the back and the nissan is tall in the front. So far without the opel engine pulled, just going off my eye and a tape measure, it looks like if I set the SR20 with the oil pan right up to the front suspension cross member then the nissan tranny mount will line up with the bolt holes for the opel automatic tranny and leave enough room for about a 10" driveshaft to the torque tube. I'm trying to find the rear axle from a isuzu impulse to put in it which is basically the same setup as the opel but it has a limited slip differential and disc brakes.
 

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Ben, when you're ready to get your driveshaft made up, take to Drive Line on Moreno Blvd. Tim, the owner, is the one that made up the itty bitty shaft on Willit? and he guaranteed it would not break. I would suggest new u-joints on each end, one for the yoke on the tranny you're gonna use and one for the rear-end you're gonna use. He can match them on the new shaft tube. HTH.
 

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Old Opeler
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Nope!

Thanks for all of the suggestions Bob.
I'm trying to find the rear axle from a isuzu impulse to put in it which is basically the same setup as the opel but it has a limited slip differential and disc brakes.
The Impulse diff is no stronger than the original Opel one - 140/150 hp will see it die too. None of the US Impulses came with LSDs - the only Piazza routinely fitted with a LSD unit from the factory was the twin-cam 5-speed manual XE Piazza. They have a "G80" factory code on their build plate when fitted with an LSD. The Impulse diff will not be of any use to you with a 200hp motor ...... even Isuzu had to replace the torque tube diff with a five-link unit in their Turbo models (180ps) as they shredded the gears.
 

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I picked up a SR20DET from a kid who had it in a 240sx. For $700 he let me take whatever I wanted so I got the engine, trans, ecu, wiring harness, intercooler and piping, radiator, drive shaft, clutch master & slave cylinders, and the electronic gage cluster.
you have no idea how lucky you are to get that deal, assuming the motor is good... normally all those parts would cost at least $2500.

i'm doing an SR20DET swap into a 240sx right now, just got it running yesterday. if you need to know anything and think i may be able to help even though mine's not an opel project, feel free to send me a PM.

the SR20DET is a completely different motor than the SR20DE, they have a similar block, but the internals and the most of the head don't share much in common. DET has COP (coil over plug) ignition whereas the DE uses a distributor, etc.

with the addition of a boost controller 250whp is not a problem at all. if it wasn't for the cost (usually $2000+ for just the motor, tranny and wiring) i'd have one in my 240sx right now.

i'm considering using a 240sx rear end in my manta project whenever i get back to work on that. if you get a '91+ they have LSD, every year has rear disks and i have never heard of anyone blowing the diff even with some 500whp cars. if you want longer gearing an early 90's 300zx diff bolts in, its a bit stronger too. i don't think it would be too hard to put in since there is 4 main mounting points for the subframe then everything bolts to the subframe including the rear sway bar. the only other mounts are for the shocks.

good luck with the project.
 

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Opeler
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369 Posts
Discussion Starter #12
Yeah, I know I got a steal on the SR20 parts; I'd been watching ebay and conversing with some companies that import them and then I was fortunate enough to find this deal locally on Craigslist. I had to pull the motor myself and the kid pretty much let me have whatever I wanted. He had decided that he was done with messing with his project but didn't want the liability of selling the whole 240sx. He was just going to sell the parts he put on it and junk the rest. Maybe I should see if he still has the body and try to get the rear axle and suspension from him. I think his was a 93'.

Jim, I guess I'll need to check my sources on the impulse axle. A guy here in the local opel club has got a GT with the impulse rear axle in it. If I remember correctly he said it was out of an 84' non-turbo impulse and he said it was a limited slip. I guess I'll have to get a hold of him and see what the story is.
 

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Old Opeler
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LSD Impulse

Jim, I guess I'll need to check my sources on the impulse axle. A guy here in the local opel club has got a GT with the impulse rear axle in it. If I remember correctly he said it was out of an 84' non-turbo impulse and he said it was a limited slip. I guess I'll have to get a hold of him and see what the story is.
There was a site over there "IsuzuPerformance" that used to import Quaife LSD units for around $1,200. The Impulse diff is exactly the same internal sizes as an Opel one so Opel Factory; ZF and Quaife units will all fit into both housings. Never say never - an Isuzu LSD or two may have crept in!
BTW: Early Vega and Astre of the 1971/72 era also had units made by Auburn available aftermarket as they had the same diff casing - till GM realised that even 2.3L Vegas could destroy them!

See This Thread: http://www.opelgt.com/forums/clutch-transmission-drive-train-upgrades/11687-positraction.html

I saw the NOS Auburn unit on eBay and later some parts of one so it may be worthwhile doing a bit of a search around Old vega/Astre owners or diff shops in your area.
 

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Opeler
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Discussion Starter #15
Thanks for the tip Ron. I'll check with Rodney to see what he has done.
 

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Opeler
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Discussion Starter #16
- the only Piazza routinely fitted with a LSD unit from the factory was the twin-cam 5-speed manual XE Piazza. They have a "G80" factory code on their build plate when fitted with an LSD. .
Jim,
Is the "G80" factory code the only way to identify an isuzu LSD without pulling the cover? and what is the weak link in the torque tube differentials? Is it just the gears?
 

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A wee bit of info on this topic, The piazza was never imported to the US and it's brake package was only imported on a mazda. All the impulses in the US didn't have the diff from a Piazza they have a different brake package and mounting system so that code is not going to be found. Rodneys car has been widened by about 4 inches to accept the isuzu rear diff so add that into your plans. but have fun
 

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Opeler
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369 Posts
Discussion Starter #18
I did some research online and as it turns out the "G80" is a universal GM option code for LSD. So, at least when I find a donor car I'll be able to check easily.
 

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Opeler
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Discussion Starter #19
Well here it goes . . . Tomorrow the engine comes out of Vette Jr. :yup:
 

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Opeler
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Discussion Starter #20
We're now under way!

My cousin came down and helped get the engine out today, but first I had to do a quick comparison check to see how many hp the turbo was adding to the old opel 1.9L. I used his Gtech Pro gadget which calculates the hp based on acceleration and weight. Since it doesn't take into account any type of drag it will naturally show lower numbers than a dyno, but that is okay since I was only concerned with the relative numbers. There was a very noticible drop in acceleration without the turbo; I had forgotten how slow it was. Based on the Gtech numbers the blow through turbo setup was adding 25hp. I also weighed the GT yesterday at the local scales so I can compare the weight before and after the swap. Vette Jr. weighed in at 2040 lbs with no driver and a little less than a half tank of fuel. It was lighter than I thought considering all the extra exhaust piping and turbo stuff.

The 1.9 is now out of the car and sitting beside it. With the engine out of the car we were able to start taking measurments, visualizing, and brainstorming. It looks like the SR20 motor mounts are in a good location but they will need to be narrowed and turned down instead of out at an angle. I think will be able to use the 1.9 crossmember without too many modifications and my cousin is thinking we should go ahead and use the opel mounts and just make up new brackets for attaching the mounts to the sides of the SR20. Even with new brackets it looks like I'm going to have to shorten the posts on the 1.9 crossmember to keep the engine low enough. The thing I am trying to decide is whether to have the engine tight against the firewall and squeeze it under the stock hood or move it forward and up and use an old camaro or corvette style shroud. Here are some pictures of the day's activites.
 

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