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Turbo C3 76 Corvette Project, LSx, 4l80E, 4 link, real street driver and strip car

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Turbo C3 76 Corvette Project, LSx, 4l80E, 4 link, real street driver and strip car

 
Old 08-18-2016, 11:42 AM
  #21  
DblTrbl
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Transmission

I chose a 4L80E because of the overdrive and high hp capabilities. It weighs more than other transmissions, but I'm not trying to set records.

I bought a 2006 trans that was supposed to be good, but it definitely had issues. I bought a few more cores (2002 and 2004) dirt cheap, $100 and $150, so I can build the trans up myself.

Built myself an adapter that lets me use the engine stand.



Built a jig to decompress the Direct and forward clutches



modified a welding clamp help manage the final drive assembly



made a lip seal tool out of brake tubing and a feeler gauge.




After searching through a number of boards, I found that there was a ton of information about modifying these transmissions. I found that some guys who are in the business, provide some info, but most of the time they are vague, incomplete or meant to scare people into not working the the trans themselves. Then there were a few guys who were knowledgeable and straightforward that gave what I felt was clear guidance, ideas and photos. Based on exhaustive search through their posts, I'm doing the following mods to get my trans to handle about 750hp. It seems 750 is the magic number where you can get by with a few inexpensive parts. Over 750, you need to swap many parts for billet.

The two most important mods appear to be to dual feed the direct clutch and the Large Ratio Boost valve sonnax 4L80E-LB1. Dual feed provides more fluid to clamp the clutches used for 3rd gear. The large ratio boost valve provides higher maximum line pressure to clamp the clutches and bands tighter while still maintaining a reasonably low line pressure when cruising.

In addition, I'm doing these:
Actuator Feed Limit repair kit transgo 48-ACT-TL
Line to Lube Pressure Regulator Valve Sonnax 34200-14K
Torlon Check ***** (you need 8) sonnax 10000-08
No Walk Case Busing sonnax 34006-SP
replace rear case bushing with torrington bearing.
More clutches in the direct drum.
increasing the size of the feed holes for 1st, 2nd and 3rd.
remove and block the 3rd gear accumulator.
drill larger pump seal drain hole.
of course I'm replacing any worn bushings, seals and gaskets.
I'm sure i'm forgetting some stuff.

I'm not going the transgo HD2 route for now. put together a notebook with photos charts, torque specs from the web and got the ATSG manual.




Transmissions are the best jigsaw puzzle ever.
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Old 08-19-2016, 04:51 PM
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One of the issues fitting a 4L80E in a c3 are the cooler lines. Stock fittings stick straight out and would not fit in the tunnel. I cut the ends off the stock fittings and welded on right angle Swagelock (just cause I happened to already have then in my junk pile) fittings.



I hope that will be enough to clear.
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Old 08-19-2016, 05:18 PM
  #23  
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Roll Bar

For mid 10s, a 5 or 6 point roll bar will do. Because I'm doing lots of fab work, and want to keep the ability to raise and lower the body, I don't want to weld the bars to the frame. Instead I'm bolting the bars to the frame. I added additional plates, with nuts welded to reinforce the frame and provide bolt-in location. The bars have an equivalent plate welded to them so it's plate to plate bolt in.







I bought a mild steel cage kit for the C3, but I wanted to get a better fit, so I rebent some of the tubes to get the cage to contour into the back of the car and tighter up against the roof and walls. Keep in mind, this car will also be a cruiser, so I want the cage as aout of the way as possible.





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Old 08-21-2016, 10:45 AM
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[QUOTE=DblTrbl;1592883041]Roll Bar

For mid 10s, a 5 or 6 point roll bar will do. Because I'm doing lots of fab work, and want to keep the ability to raise and lower the body, I don't want to weld the bars to the frame. Instead I'm bolting the bars to the frame. I added additional plates, with nuts welded to reinforce the frame and provide bolt-in location. The bars have an equivalent plate welded to them so it's plate to plate bolt in.







I bought a mild steel cage kit for the C3, but I wanted to get a better fit, so I rebent some of the tubes to get the cage to contour into the back of the car and tighter up against the roof and walls. Keep in mind, this car will also be a cruiser, so I want the cage as aout of the way as possible.




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Old 08-21-2016, 01:56 PM
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I just saw a deal in Car Craft or Hot Rod where they were swapping a trans with the same issue. They showed some close fitting 90* fittings made for -6 lines. I'd much prefer that to the hose clamp hose deal if you can.

JIM
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Old 08-21-2016, 04:13 PM
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Originally Posted by 427Hotrod View Post
I just saw a deal in Car Craft or Hot Rod where they were swapping a trans with the same issue. They showed some close fitting 90* fittings made for -6 lines. I'd much prefer that to the hose clamp hose deal if you can.

JIM
Thanks, I'll look into those. With the swagelock, the tube part is removable and can be replaced by a more secure hose setup. Right this moment, there is no cooler and the hose is looped back. Gotta start thinking about where to place a cooler.
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Old 08-21-2016, 07:12 PM
  #27  
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The 90 deg fitting on the right looks like a standard SAE -6 that any Hydraulic supply shop should be able to provide. However I wouldn't be surprised if the Threads on the modern Transmissions are not Metric. If so, a Hydraulic supply store should still be able to convert to -6 pretty easy. Then from the -6 Jic male You can go to Tubing or Hose.
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Old 08-22-2016, 09:35 AM
  #28  
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Originally Posted by DblTrbl View Post
It's time for a build thread.

I've built lots of fast turbo cars before (Dodge), but with only half the cylinders. The goal for my first 8 cyl american muscle car is car that can really cruise the streets comfortably as well as race at the strip, somewhere in the 10s.

It's going to look stock, not with some huge hood bulge, or open headers poking out of the nose. I'm keeping the heater and the retractable headlamps. As most of you who have worked with C3s before know, it's tight for turbo and stock appearance.

I like to do things a little different from most, so I'm not just dropping in some bolt ons. It's also a platform for me to test out some of my crazy ideas.

In my opinion, 4l80E fits the bill for a street/strip car since it has overdrive and huge power capabilities.

After I get most everything mocked up and tested, I'm going to tear it all down and send the chassis out for powder coating.

For mid 10s, gotta have the roll bar. I think I can get by with 5 point with hinged drivers side arm bar, so I can comfortably street the car.

Picked up a 2002 5.3 and 4l60e from a 12,000 mile wreck for $400 from JY. But water got into the engine while it sat in the Tahoe for 13 years and needed a rebuild. Sold the 4l60E for $350 which paid for the re-bore and new pistons and rings. I'm keeping this engine's internals stock for starters, but expect at some point to replace it with a forged 6.0.
I had two T76 setups on my Firebird. Different engine bay than my C3's, but I'm fairly confident both setups would have fit fine based on the turbo location. If you are interested in pictures I can send a bunch your way, just PM me your email.

The two setups I did, one I did the crossover under the oil pan. That worked out great but plug access to #6 was close.

The second one I did the crossover in the front. I wasn't as happy with that routing, so I'd avoid it especially on a C3.


I'm running a blower on the Firebird now, but I designed the mounting brackets based on the C3 engine bay so if I want to transfer it to one of my C3's I can. (Passenger side mount). Giving up A/C and smog pump is a must of course.

-- Joe
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Old 08-22-2016, 11:28 AM
  #29  
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Joe, why'd you change to a blower? did you get the performance you expected from the turbo setup?

I was juggling whether to do a twin setup or a side turbo or in front. I couldn't figure out how to to keep the AC on any of them. Already did a twin turbo on a very different car, so I went with the single turbo in front. Time will tell if I like the layout.

Is that an LS engine in the firebird?
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Old 08-22-2016, 02:19 PM
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Originally Posted by DblTrbl View Post
Joe, why'd you change to a blower? did you get the performance you expected from the turbo setup?

I was juggling whether to do a twin setup or a side turbo or in front. I couldn't figure out how to to keep the AC on any of them. Already did a twin turbo on a very different car, so I went with the single turbo in front. Time will tell if I like the layout.

Is that an LS engine in the firebird?
Hello,

I went back to a blower (procharger, then turbo, then vortech) because I wasn't digging the heat that all of the piping was putting into the engine bay. Also the T76 was a little too small on my 412" SBC, and I couldn't fit a larger turbo under the hood.

I have a SBC in the formula now, but an LS on the stand. The location is essentially the same and I'd route everything the same. The video shows a singleplane intake with a cable-driven LS2 throttle body. Eventually the SBC will go in my '75 vette and I'll put the LS in the firebird.



-- Joe
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Old 08-22-2016, 07:25 PM
  #31  
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Ok, next I went a little overboard. I had some time between work contracts, so I designed and built a 4l80E transmission controller.


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Old 08-22-2016, 09:23 PM
  #32  
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The controller processor is an Arduino board. Started off with plans of making a simple controller and then, like the rest of this corvette project, I had a major case of scope creep and kept adding features.

First I added the required set of peripheral components like VR sensor for MPH, drivers for the solenoids, map sensor etc.

Then I added a display panel and some buttons and an Xbox Controller Joystick. The control panel doubles as a dashboard and a way of changing shift, boost and other parameters. Then I added more sensors. The trans controller also serves as a boost controller.

So I went a little crazy and created a bunch of driving modes. Each driving mode has it's own shifting and boost characteristics.

For cruising around, there is Cruise mode. Cruise mode shifts based on MPH and load (vacuum/boost). Cruise mode can use all 4 gears and lockup. Shift tables for each gear/load can be changed from the control panel. Rules are in place to protect against downshifts that will overrev the engine and also shift up a gear in case the engine exceeds the maximum rev limit. Each gear also has a target boost. Line pressure is controlled by load and mode.

Some other modes, Burnout mode. Only shifts based on engine RPM and only goes up to a preset gear. When the burnout is done, the controller automatically changes to Drag mode. Drag mode also shifts by RPM and only shifts up to 3rd gear. No 4th, no lockup. Drag mode also has a target boosts for each gear.

There is also a Dyno mode and a joystick (similar to paddle shift) mode.

The controller also logs maximum/minimum values and alarms.

Display shows gear, mph, rpm, oil pressure, fuel pressure, boost/vacuum, boost target for current gear, oil temp and engine temp on the primary display. There is a switch to toggle in 2 additional displays for things like line pressure, trans temp, and max/minimum readings reached.

I built a simulator using another Arduino board to test as much as possible before it goes in the car.

I have no intentions of making a product of this. It's a hobby and I've ruined some of my other hobbies by turning them into business before.
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Old 08-23-2016, 02:23 AM
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Serious skills here.....txs for sharing
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Old 08-23-2016, 09:49 AM
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Originally Posted by DblTrbl View Post
The controller processor is an Arduino board. Started off with plans of making a simple controller and then, like the rest of this corvette project, I had a major case of scope creep and kept adding features.

First I added the required set of peripheral components like VR sensor for MPH, drivers for the solenoids, map sensor etc.

Then I added a display panel and some buttons and an Xbox Controller Joystick. The control panel doubles as a dashboard and a way of changing shift, boost and other parameters. Then I added more sensors. The trans controller also serves as a boost controller.

So I went a little crazy and created a bunch of driving modes. Each driving mode has it's own shifting and boost characteristics.

For cruising around, there is Cruise mode. Cruise mode shifts based on MPH and load (vacuum/boost). Cruise mode can use all 4 gears and lockup. Shift tables for each gear/load can be changed from the control panel. Rules are in place to protect against downshifts that will overrev the engine and also shift up a gear in case the engine exceeds the maximum rev limit. Each gear also has a target boost. Line pressure is controlled by load and mode.

Some other modes, Burnout mode. Only shifts based on engine RPM and only goes up to a preset gear. When the burnout is done, the controller automatically changes to Drag mode. Drag mode also shifts by RPM and only shifts up to 3rd gear. No 4th, no lockup. Drag mode also has a target boosts for each gear.

There is also a Dyno mode and a joystick (similar to paddle shift) mode.

The controller also logs maximum/minimum values and alarms.

Display shows gear, mph, rpm, oil pressure, fuel pressure, boost/vacuum, boost target for current gear, oil temp and engine temp on the primary display. There is a switch to toggle in 2 additional displays for things like line pressure, trans temp, and max/minimum readings reached.

I built a simulator using another Arduino board to test as much as possible before it goes in the car.

I have no intentions of making a product of this. It's a hobby and I've ruined some of my other hobbies by turning them into business before.
I almost started getting a little dizzy reading all that

Sounds like you are having fun! That's what it's all about. Keep up the good work. I'm enjoying reading up on your progress
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Old 08-23-2016, 11:15 AM
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Originally Posted by bmans vette View Post
Serious skills here.....txs for sharing
Thanks.



Originally Posted by 76Rat View Post
I almost started getting a little dizzy reading all that

Sounds like you are having fun! That's what it's all about. Keep up the good work. I'm enjoying reading up on your progress
I felt a little dizzy when I was writing the code. I'm still dizzy.


Here is the controller now:




And the control panel/dashbord:

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Old 08-24-2016, 12:02 AM
  #36  
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Shifting through the gears in paddle mode using the Xbox controller Joystick.

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Old 08-24-2016, 10:31 AM
  #37  
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Nice build. Some serious fab skills.
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Old 08-24-2016, 06:30 PM
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You're like a fearless wizard! Looks like there's nothing you won't tackle.

I'm running a 4l80 using 90 - 6AN on center hub and 22.5 - 6AN on the front, braided stainless lines. Still clearance in the tunnel for insulation too. Tightest spot was the u-joint/yolk on tailshaft.
Nice work! , good luck.
jim
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Old 08-24-2016, 06:39 PM
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check this old thread out... this guy stuffed twins in and also ran 4l80e.. he was/is quite a fabricator too

http://www.corvettefaq.com/c3/427sbc.htm
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Old 08-24-2016, 08:09 PM
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Originally Posted by jimvette999 View Post
check this old thread out... this guy stuffed twins in and also ran 4l80e.. he was/is quite a fabricator too

http://www.corvettefaq.com/c3/427sbc.htm
I believe Monty's C3 ran in the nines with stock wheels and tires.

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