Boxster LS1 swap: Ideas needed plz
03-30-2010, 05:04 PM
#41
keep the torque and fix the problem by getting something that will hold the power. I researched trannys a while back for a ultima GTR and they sue the porsche trannys that can hold oodles of power. you may try their website and look at the vendors for those trannys that are already built. i remember seeing some that could hold over 700hp for bout 3k plus core
03-30-2010, 06:33 PM
#42
Hey, it's still going? That's great, I just emailed you last night. Any fitment issues? Eric mentioned he has an adapter plate, so I know that the starter issue has been solved. I think I can handle any mounting issues will a bit of steel and some welding, but what about the pulleys? Do they hit the firewall?
I found out yesterday that the G86.20 tranny (from the Boxster S) is rated for just 280 ft-lb input torque (Getrag spec). That is not good. I had read that this is the same gearbox as the 996TT (with swapped ring gear orientation), but that is definitely not true. The TT uses a Getrag with a much higher torque rating.
So I was thinking about destroking the LS1 to reduce the torque on the G86 input shaft. Then upgrade the valve springs to get to 7200 rpm redline (which is the same as Boxster S) to recoup some of the lost hp caused by the shorter stroke. But then the project price goes up and you miss out on some of that monster torque. I'd like to keep it around $3-4k overall because that's what I'd expect to get for my 3.2 L after pulling it.
I found out yesterday that the G86.20 tranny (from the Boxster S) is rated for just 280 ft-lb input torque (Getrag spec). That is not good. I had read that this is the same gearbox as the 996TT (with swapped ring gear orientation), but that is definitely not true. The TT uses a Getrag with a much higher torque rating.
So I was thinking about destroking the LS1 to reduce the torque on the G86 input shaft. Then upgrade the valve springs to get to 7200 rpm redline (which is the same as Boxster S) to recoup some of the lost hp caused by the shorter stroke. But then the project price goes up and you miss out on some of that monster torque. I'd like to keep it around $3-4k overall because that's what I'd expect to get for my 3.2 L after pulling it.
03-31-2010, 03:39 AM
#43
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Hey, it's still going? That's great, I just emailed you last night. Any fitment issues? Eric mentioned he has an adapter plate, so I know that the starter issue has been solved. I think I can handle any mounting issues will a bit of steel and some welding, but what about the pulleys? Do they hit the firewall?
I found out yesterday that the G86.20 tranny (from the Boxster S) is rated for just 280 ft-lb input torque (Getrag spec). That is not good. I had read that this is the same gearbox as the 996TT (with swapped ring gear orientation), but that is definitely not true. The TT uses a Getrag with a much higher torque rating.
So I was thinking about destroking the LS1 to reduce the torque on the G86 input shaft. Then upgrade the valve springs to get to 7200 rpm redline (which is the same as Boxster S) to recoup some of the lost hp caused by the shorter stroke. But then the project price goes up and you miss out on some of that monster torque. I'd like to keep it around $3-4k overall because that's what I'd expect to get for my 3.2 L after pulling it.
I found out yesterday that the G86.20 tranny (from the Boxster S) is rated for just 280 ft-lb input torque (Getrag spec). That is not good. I had read that this is the same gearbox as the 996TT (with swapped ring gear orientation), but that is definitely not true. The TT uses a Getrag with a much higher torque rating.
So I was thinking about destroking the LS1 to reduce the torque on the G86 input shaft. Then upgrade the valve springs to get to 7200 rpm redline (which is the same as Boxster S) to recoup some of the lost hp caused by the shorter stroke. But then the project price goes up and you miss out on some of that monster torque. I'd like to keep it around $3-4k overall because that's what I'd expect to get for my 3.2 L after pulling it.
04-01-2010, 08:38 PM
#44
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Not sure how this would work. I just went out and took some measurements. The LS1 fits easily in height and width, but it seems to be at least 5" longer than the Porsche M96, which is just 20" long. The pulleys on the M96 are already very close to the firewall. Thus, there are four possible solutions:
1. Move the firewall forward (not good, since a 6' driver is already pretty close to the steering wheel).
2. Move the engine back (not good since this would put the output flanges on the tranny 5" further back, which means new, longer axles would be at a less-than-ideal angle).
3. Get a shorter tranny? No idea if that's possible.
4. Maybe use the LS1 from a FWD application?
1. Move the firewall forward (not good, since a 6' driver is already pretty close to the steering wheel).
2. Move the engine back (not good since this would put the output flanges on the tranny 5" further back, which means new, longer axles would be at a less-than-ideal angle).
3. Get a shorter tranny? No idea if that's possible.
4. Maybe use the LS1 from a FWD application?
04-01-2010, 11:06 PM
#45
Not sure how this would work. I just went out and took some measurements. The LS1 fits easily in height and width, but it seems to be at least 5" longer than the Porsche M96, which is just 20" long. The pulleys on the M96 are already very close to the firewall. Thus, there are four possible solutions:
1. Move the firewall forward (not good, since a 6' driver is already pretty close to the steering wheel).
2. Move the engine back (not good since this would put the output flanges on the tranny 5" further back, which means new, longer axles would be at a less-than-ideal angle).
3. Get a shorter tranny? No idea if that's possible.
4. Maybe use the LS1 from a FWD application?
1. Move the firewall forward (not good, since a 6' driver is already pretty close to the steering wheel).
2. Move the engine back (not good since this would put the output flanges on the tranny 5" further back, which means new, longer axles would be at a less-than-ideal angle).
3. Get a shorter tranny? No idea if that's possible.
4. Maybe use the LS1 from a FWD application?
4.) The front parts from the LS4 can be installed on the other LS engines if necessary. This will shorten the engine about 2 inches. The other option would be to run an electric water pump.
04-02-2010, 02:47 PM
#46
The LS4 has a shorter snout on the crank. In fact, the crank is shorter on both ends. That's why the LS4 can be 2" shorter than any other LS. And the LS4 block can be bored to 5.7L, so you can have an LS6 in a smaller package. If you're doing a transverse install, you should get on some other forums. The best info is probably going to be on www.fiero.nl Mostly from Rickady88GT and blckcfy, If I'm remembering correctly the spelling of their user names.
You should do this swap. When I had my '95 Z28 conv, w/ A4 and econo gearing, I beat a Boxster, despite me having a heavy passenger.
You should do this swap. When I had my '95 Z28 conv, w/ A4 and econo gearing, I beat a Boxster, despite me having a heavy passenger.
04-02-2010, 10:52 PM
#48
So I was thinking about destroking the LS1 to reduce the torque on the G86 input shaft. Then upgrade the valve springs to get to 7200 rpm redline (which is the same as Boxster S) to recoup some of the lost hp caused by the shorter stroke. But then the project price goes up and you miss out on some of that monster torque. I'd like to keep it around $3-4k overall because that's what I'd expect to get for my 3.2 L after pulling it.
Though I can't quite get an exact measurement with the motor in the car, my LS1 with LS6 dampener and LS2 water pump measures about 25". If the LS4 stuff takes off another 2", that gets you down to 23" but I suspect there'd still be no room for the accessoriy drive.
I'm considering a BMW or a Boxster for my next LSx project, so I look to this one with keen interest. Maybe I'll pay a visit one of these days to the guy (BR) that's doing this one, since he's only an hour from me.
Andy1
04-03-2010, 01:49 AM
#49
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a wise man once said " fear not the hacksaw blade " 
seriously , can't you cut out a recess (sp?) where the accesory drive will go and then fab up a cover? it might bulge out a few inches but i bet you it won't be noticable once you get it covered up . ( unless there is something important in thea area and you can't cut it )
seriously , can't you cut out a recess (sp?) where the accesory drive will go and then fab up a cover? it might bulge out a few inches but i bet you it won't be noticable once you get it covered up . ( unless there is something important in thea area and you can't cut it )
04-03-2010, 11:59 AM
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a wise man once said " fear not the hacksaw blade "
seriously , can't you cut out a recess (sp?) where the accesory drive will go and then fab up a cover? it might bulge out a few inches but i bet you it won't be noticable once you get it covered up . ( unless there is something important in thea area and you can't cut it )
seriously , can't you cut out a recess (sp?) where the accesory drive will go and then fab up a cover? it might bulge out a few inches but i bet you it won't be noticable once you get it covered up . ( unless there is something important in thea area and you can't cut it )
...and then there's an adapter plate that is going to add another inch or so.
I've been looking around, and it seems like the LS1 could be made to be 24-25" long, but that's still 4" too long!
@Isolde: this is an S. Your Z28 would have a harder time beating it in a straight line, but then again, this will be a commuter/track car. I do not intend to take it to the strip, ever. Instead, it needs to sustain high revs and high-g cornering for 20 minute sessions without overheating or getting oil starved.
@zerosoul914: From the pics I have seen, the 996 should be able to fit an LS1. There seems to be a several inches back there where the airbox sits that could be used.
Looks like the VH45 is a bit shorter than the LS1 (the extra width of the DOHC isn't a problem since the M96 is 28" wide), but that's another forum...
04-03-2010, 05:46 PM
#52
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How about moving the tranny a bit back ?
i might go that route on my 996 if need be
i don't know about your case , but if there is some space behind the tranny to move it back you can mount the engine as close as you can to the front bulkhead , slap on the adapter and the tranny , then fab a new trans mount to work with the new location .
i'm sure the change would not affect the shifting cables or the cv joints much .
can you get us some pics of what space you have to work with ?
i might go that route on my 996 if need be
i don't know about your case , but if there is some space behind the tranny to move it back you can mount the engine as close as you can to the front bulkhead , slap on the adapter and the tranny , then fab a new trans mount to work with the new location .
i'm sure the change would not affect the shifting cables or the cv joints much .
can you get us some pics of what space you have to work with ?
04-03-2010, 08:21 PM
#53
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How about moving the tranny a bit back ?
i might go that route on my 996 if need be
i don't know about your case , but if there is some space behind the tranny to move it back you can mount the engine as close as you can to the front bulkhead , slap on the adapter and the tranny , then fab a new trans mount to work with the new location .
i'm sure the change would not affect the shifting cables or the cv joints much .
can you get us some pics of what space you have to work with ?
i might go that route on my 996 if need be
i don't know about your case , but if there is some space behind the tranny to move it back you can mount the engine as close as you can to the front bulkhead , slap on the adapter and the tranny , then fab a new trans mount to work with the new location .
i'm sure the change would not affect the shifting cables or the cv joints much .
can you get us some pics of what space you have to work with ?
04-03-2010, 08:22 PM
#54
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How about moving the tranny a bit back ?
i might go that route on my 996 if need be
i don't know about your case , but if there is some space behind the tranny to move it back you can mount the engine as close as you can to the front bulkhead , slap on the adapter and the tranny , then fab a new trans mount to work with the new location .
i'm sure the change would not affect the shifting cables or the cv joints much .
can you get us some pics of what space you have to work with ?
i might go that route on my 996 if need be
i don't know about your case , but if there is some space behind the tranny to move it back you can mount the engine as close as you can to the front bulkhead , slap on the adapter and the tranny , then fab a new trans mount to work with the new location .
i'm sure the change would not affect the shifting cables or the cv joints much .
can you get us some pics of what space you have to work with ?
I don't have pics of my car at the moment, but here are some from google. First, a bottom view of the gearbox here.
And the top view of the engine here. The front is on the left, gearbox on the right. You can see an accessory pulley off to the left... it really is a short engine! The red metal on the left side of the pic is the top of the firewall. The tan colored leather/carpet is the interior of the car.
04-04-2010, 01:26 AM
#55
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ok , i might be going off on a limb here , but after seeing this pic i beleive it is easy to do!
look at how the transmission has a three hole bracket on each side ( look on the pass. side , the rearmost control arm points to it) , well attatched to that bracket is another bracket (black one ) that goes to the transmission mount ( wich looks alot like 996 engine mounts) . the key ( according to my limited number of grey cells
) is in making a new set of these (black) brackets where they curve backwards in a way that mounts the tranny further back. now i know from looking at these pictures that there is a ton of room behind the tranny where the muffler is, but like you mentioned above the cv axles might be an issue . can you get a pic just like the second one ( side shot of the rear axle) but without the rotor being in the way ?
thanks for the pics by the way !
look at how the transmission has a three hole bracket on each side ( look on the pass. side , the rearmost control arm points to it) , well attatched to that bracket is another bracket (black one ) that goes to the transmission mount ( wich looks alot like 996 engine mounts) . the key ( according to my limited number of grey cells
) is in making a new set of these (black) brackets where they curve backwards in a way that mounts the tranny further back. now i know from looking at these pictures that there is a ton of room behind the tranny where the muffler is, but like you mentioned above the cv axles might be an issue . can you get a pic just like the second one ( side shot of the rear axle) but without the rotor being in the way ?thanks for the pics by the way !
04-04-2010, 01:48 AM
#56
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here's a better pic of the brackets :
and i know this might get the project out or its intended budget , but have you looked into the audi transmissions?
the axle flanges are much closer to the engine than in a porsche .
could be a solution to the CV placement issue ?
here is one example :
and i know this might get the project out or its intended budget , but have you looked into the audi transmissions?
the axle flanges are much closer to the engine than in a porsche .
could be a solution to the CV placement issue ?
here is one example :
Last edited by 1dirtyZ; 04-04-2010 at 01:59 AM.
04-04-2010, 10:38 AM
#57
ok how about this idea...
instead of moving the firewall forward what about moving everything back and mounting some of the thigns into the rear trunk area...?or hell what about even turning the motor sideways like in a FWD application and using a FWD tranny of some kind?
instead of moving the firewall forward what about moving everything back and mounting some of the thigns into the rear trunk area...?or hell what about even turning the motor sideways like in a FWD application and using a FWD tranny of some kind?
04-08-2010, 10:18 AM
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how to loose the 5 inches Hi Ethan,
What is the horizontal distance between the front of the boxster tranny where it mounts to the engine) and the center of the output shaft flange? I used a 'short' 930 tranny on my LS6 swap into a 911. The 930 is a large four speed capable of about 600 ft-lbs of touque. In 1976/77 they made a short version that was 2 inches shorter than the later 930's. It is also shorter than the G50 that came even later.
If you will post that measurement, I'll measure my tranny. This combo may buy you a few inches without having to shift your axels.
Good luck and please keep this project going. There is a lot of interest in this type of conversion! I used to own a 2002 Boxster S. I loved the car, but the 252 hp was a bit anemic.
Mike
What is the horizontal distance between the front of the boxster tranny where it mounts to the engine) and the center of the output shaft flange? I used a 'short' 930 tranny on my LS6 swap into a 911. The 930 is a large four speed capable of about 600 ft-lbs of touque. In 1976/77 they made a short version that was 2 inches shorter than the later 930's. It is also shorter than the G50 that came even later.
If you will post that measurement, I'll measure my tranny. This combo may buy you a few inches without having to shift your axels.
Good luck and please keep this project going. There is a lot of interest in this type of conversion! I used to own a 2002 Boxster S. I loved the car, but the 252 hp was a bit anemic.
Mike
04-09-2010, 02:40 AM
#60
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Hi Ethan,
What is the horizontal distance between the front of the boxster tranny where it mounts to the engine) and the center of the output shaft flange? I used a 'short' 930 tranny on my LS6 swap into a 911. The 930 is a large four speed capable of about 600 ft-lbs of touque. In 1976/77 they made a short version that was 2 inches shorter than the later 930's. It is also shorter than the G50 that came even later.
If you will post that measurement, I'll measure my tranny. This combo may buy you a few inches without having to shift your axels.
Good luck and please keep this project going. There is a lot of interest in this type of conversion! I used to own a 2002 Boxster S. I loved the car, but the 252 hp was a bit anemic.
Mike
What is the horizontal distance between the front of the boxster tranny where it mounts to the engine) and the center of the output shaft flange? I used a 'short' 930 tranny on my LS6 swap into a 911. The 930 is a large four speed capable of about 600 ft-lbs of touque. In 1976/77 they made a short version that was 2 inches shorter than the later 930's. It is also shorter than the G50 that came even later.
If you will post that measurement, I'll measure my tranny. This combo may buy you a few inches without having to shift your axels.
Good luck and please keep this project going. There is a lot of interest in this type of conversion! I used to own a 2002 Boxster S. I loved the car, but the 252 hp was a bit anemic.
Mike
The car's themselves have phenomenal chassis and suspension development already into them. There's a well known boxster owner in the forums who goes by "grantsfo" that has shown what these cars are capable off. His stripped out self-made "spyder" received the top time of the day at a GGR autoX event and tore up the previously dominant 914s
