SC400 Lightweight Roll Cage material??

[spf_lexus]

Your LS must ride like rails w/ the cage and the weight savings. Fab work is top notch too. With the door glass taken out I think you might be able to hit 3000 even. My sc400 has a lot of reduction but supercharger + dash + glass still and im down to 3100lb.

Its too bad the LS doesnt haver a arbon or fiberglass hood option. I removed mine and took it in to get painted and its an easy 80-90lb steel hood. I wonder if you could cut the top layer of steel off and keep the undersid stamped skeleton... then maybe lay a small layer of fiberglass? Could mean another 30lb or so?

 

[spf_lexus]

Oops forgot to ask, have you redone the stock exhaust? If you delete the front cats + center resonator and rear 4 mufflers... replace the system with a single 3" single exit. Another 75lb can be taken out.

 

[Spinnetti]

Your LS must ride like rails w/ the cage and the weight savings. Fab work is top notch too. With the door glass taken out I think you might be able to hit 3000 even. My sc400 has a lot of reduction but supercharger + dash + glass still and im down to 3100lb.

Its too bad the LS doesnt haver a arbon or fiberglass hood option. I removed mine and took it in to get painted and its an easy 80-90lb steel hood. I wonder if you could cut the top layer of steel off and keep the undersid stamped skeleton... then maybe lay a small layer of fiberglass? Could mean another 30lb or so?

Thanks.. I don't have a tube bender, so partnered with a guy and we did together. Eventually I may buy a bender so I don't have to mess around. I already have a nice TiG welder.

Not shown in the pics, I gutted the doors even further, removing the strikers and latches in the back and welding the door skins to the body. Even lighter and stiffer than it was before... Its solid as rock now!

Exhaust is stock except: cut out all 3 cats and both rear mufflers... Cut of the exhaust right at the diff, and only have the resonators.. Sounds great, and not too loud.

Next question: How do I make more power out of this beast? I'm not talking big stuff, but little stuff. Is ignition timing adjustable? make any more power with a bit more advance? any cheap ecu mods to get any more out of it? I've put in iridiums at .044 gap, done the exhaust as mentioned, got rid of the AC and clutch fan, removed the emissions stuff (its a race car), put a great big oil filter and 0 weight oil, but nothing else to the engine. ideas?

 

[spf_lexus]

The stock toyota ecu is very very cryptic and trying to crack it is virtually impossible. You can grab Unichip or any piggyback that can modify both timing and afr. Just 1 of the 2 wont be produce enough gain for the price so keep that in mind. I have seen some solid NA gains on the UZ. The UZ really opens up when you lean the ratio a solid point with a few degrees of timing. I have seen a few dyno plots netting 10-12% gains.

Another easy mod would be a high stall torque convertor. David sells them with a 2800 stall but he can get them set with any stall rate you like with 1/8th the price of the trendy dragon tc's. Since its on the track, a higher, 3500 stall would really wake the LS up off the line and lower gears. It can shave off a solid second 0-60. Its like launching at peak tq every time.

Another option is to run the stock ECU and install Lextreme's stage I or II cams for another 10-15% NA power. stock ecu works great with cams.

Also, i forgot the brand name but there is a new company out selling headers for the 3uzfe ls400 and this will also fit the 4.0 ls400. Another easy 10-15whp gains.


Also, the stock auto can be modified to deliver neck snapping shifts as long as you dont turbo/supercharge it (perfect for your application). Check the supra forums, they have an in depth how to for the a342e auto. Basically they add 15mm height shims inside each shift accumulator, effectively deleting the built in shift delay that gives lexus trans their inperceivable shifts.

 

[Spinnetti]

The stock toyota ecu is very very cryptic and trying to crack it is virtually impossible. You can grab Unichip or any piggyback that can modify both timing and afr. Just 1 of the 2 wont be produce enough gain for the price so keep that in mind. I have seen some solid NA gains on the UZ. The UZ really opens up when you lean the ratio a solid point with a few degrees of timing. I have seen a few dyno plots netting 10-12% gains.

Another easy mod would be a high stall torque convertor. David sells them with a 2800 stall but he can get them set with any stall rate you like with 1/8th the price of the trendy dragon tc's. Since its on the track, a higher, 3500 stall would really wake the LS up off the line and lower gears. It can shave off a solid second 0-60. Its like launching at peak tq every time.

Another option is to run the stock ECU and install Lextreme's stage I or II cams for another 10-15% NA power. stock ecu works great with cams.

Also, i forgot the brand name but there is a new company out selling headers for the 3uzfe ls400 and this will also fit the 4.0 ls400. Another easy 10-15whp gains.


Also, the stock auto can be modified to deliver neck snapping shifts as long as you dont turbo/supercharge it (perfect for your application). Check the supra forums, they have an in depth how to for the a342e auto. Basically they add 15mm height shims inside each shift accumulator, effectively deleting the built in shift delay that gives lexus trans their inperceivable shifts.

Thanks... So, pardon my ignorance, but as a self confessed auto tranny hater, how would the higher stall TQ make me faster? What exactly does that do different?

thanks.

 

[spf_lexus]

the "stall" speed is the rpm that will lock the torque convertor and allow the engine to feed the trans. the torque convertor will allow a pre set amount of fluid through it and as the engine rpms rises and reaches the stall speed, the convertor will lock together. Stock is 2000rpm or so. Pretty sure davids are set to 2800rpm. By raising this up, the engine will be higher into the torque curve when the unit locks together. very similar to a manual where you drop the clutch a bit higher for that extra kick off the line. it wont be a night and day change if your only concerned with sustained high speeds. The biggest changes occur from 1st and 2nd gear. I suppose hairpin turns that requires a lot of downshifting might exploit a higher stall. I have run 3 of them over the last few years and no problems.

 

[Spinnetti]

IC, thanks... on a road course, its only by horrible accident that I'd ever see first, and now that I've gone to the 4.27 I'd pull my hair out if I got that slow! Real issue is the ultra wide gear ratios. There needs to be more happening between 2-3 as they are both too long (one reason I went to the 4.27 and also run shorter tires to get even more, but its still too slow).... Are there later boxes that will bolt up with more gears? I'd rarely see top end on a race track, so want to pull down top speed to 120 or so such that below that its a lot quicker.

Cheers,

 

[spf_lexus]

the 5 and 6 speed auto swap has been discussed but I have never seen one swapped myself. However, I do know that the stock a341 from the sc400 has slightly shorter ratios than the LS. Dsvid and myself "frankensteined" a 91 LS with a 91 SC trans and there was a noticable gain in tq. Bolts right up, plugs are the exact same but you will need to swap the LS speed sensor or else the speedo wont work which might not be an issue for you?

basically the 4.27 + sc400 auto.. you have a complete SC400 drivetrain!

As fore the torque convertor, it seems like it would be a waste for your application. Shimming the solenoids WILL help you tho. I get frustrated when im trying to lay down 400+hp and then the trans counts 1... 2... 3... SHIFT. Its so slow sometimes it feels like the car slows down before engaing the next gear. I know if your not throwing a lot of power at it, the auto will last a long time w/ this mod. If I shimmed mine w/ my output I would destroy the sprag/cage in no time. For an NA apllication, its an awesome mod. You can DIY for like $20 versus a $500+ valve body upgrade.

Here's the DIY for the trans mod if your interested:

http://www.supraforums.com/forum/showthread.php?267655-How-to-make-a-a340-last(56kers-take-a-nap)

 

[Spinnetti]

the 5 and 6 speed auto swap has been discussed but I have never seen one swapped myself. However, I do know that the stock a341 from the sc400 has slightly shorter ratios than the LS. Dsvid and myself "frankensteined" a 91 LS with a 91 SC trans and there was a noticable gain in tq. Bolts right up, plugs are the exact same but you will need to swap the LS speed sensor or else the speedo wont work which might not be an issue for you?

basically the 4.27 + sc400 auto.. you have a complete SC400 drivetrain!

As fore the torque convertor, it seems like it would be a waste for your application. Shimming the solenoids WILL help you tho. I get frustrated when im trying to lay down 400+hp and then the trans counts 1... 2... 3... SHIFT. Its so slow sometimes it feels like the car slows down before engaing the next gear. I know if your not throwing a lot of power at it, the auto will last a long time w/ this mod. If I shimmed mine w/ my output I would destroy the sprag/cage in no time. For an NA apllication, its an awesome mod. You can DIY for like $20 versus a $500+ valve body upgrade.

Here's the DIY for the trans mod if your interested:

http://www.supraforums.com/forum/showthread.php?267655-How-to-make-a-a340-last(56kers-take-a-nap)

Cool thanks. somebody said adjusting the trans cable off the throttle is supposed to do something?

Looks like when/if the trans blows, I'll replace with the SC400 one - you are right, I don't care about the speed sensor... You don't happen to know what the specific gear differences are do you?


I'll look up the shimming thing. I had read up before on that, and seem to be mixed opinions?

thnx

 

[spf_lexus]

[QUOTECool thanks. somebody said adjusting the trans cable off the throttle is supposed to do something?

][/QUOTE]

The trans cable can be maxed out for a faster shift. Totally forgot about the line pressure! Max the adjustment nut all the way to the tip and go test drive. It will slam into drive but its not a bad thing, as it actually saves the clutch packs from wearing. It wont cut the shifts in half or anything but a noticable improvement.

No problemo.

I personally do not have the actual ratios between the LS and SC but at 75mph, the sc auto will be about 200rpm higher than the LS.

The mixed opinions about shimming the accumulators is mostly about the durability when boosted on top of the mod. without a big turbo or supercarger it will work great. I know a couple supra guys had stronger sprag/cage combos to range the 350whp limit into the 500whp range.

I have not tried this yet but have rode in an SC with the mod and it was neck snapping. The shift from 1-2 and 2-3 has the longest shift time and these 2 accumulators are the ones recieving the shims.

 

[Spinnetti]

[QUOTECool thanks. somebody said adjusting the trans cable off the throttle is supposed to do something?

]

The trans cable can be maxed out for a faster shift. Totally forgot about the line pressure! Max the adjustment nut all the way to the tip and go test drive. It will slam into drive but its not a bad thing, as it actually saves the clutch packs from wearing. It wont cut the shifts in half or anything but a noticable improvement.

No problemo.

I personally do not have the actual ratios between the LS and SC but at 75mph, the sc auto will be about 200rpm higher than the LS.

The mixed opinions about shimming the accumulators is mostly about the durability when boosted on top of the mod. without a big turbo or supercarger it will work great. I know a couple supra guys had stronger sprag/cage combos to range the 350whp limit into the 500whp range.

I have not tried this yet but have rode in an SC with the mod and it was neck snapping. The shift from 1-2 and 2-3 has the longest shift time and these 2 accumulators are the ones recieving the shims.[/QUOTE]

ok, I looked into this stuff a bit.... 'Shimming' is just the poor mans way to up the spring rate. Better would be just to put in a spring with the rate you want, but same effect.

Reason SC400 turns a couple hundred rpm more than the LS at 75 is because the LS has a 3.62 and the SC400 a 3.92 (the 4.27 is only on the sc300).... so that's just diff, not trans... worth a look further though...

If the car lasts through this race, I'll see about maybe pulling the trans and doing the shim thing.. not sure yet... we spend most of the time in 2nd and 3rd, so might be worth doing the one anyway. If the latest round of mods are good enough, I may just leave as is... We had the 3rd fastest time on the first outing totally green, so maybe not much need to be any faster (focus on fuel endurance and pitstops will yield more).

so on the cable, I assume you meant to adjust it so that it is as TIGHT as it will go, trying to fool the trans that you are putting in more throttle than you actually are?

Thanks...

 

[spf_lexus]

Reason SC400 turns a couple hundred rpm more than the LS at 75 is because the LS has a 3.62 and the SC400 a 3.92 (the 4.27 is only on the sc300).... so that's just diff, not trans... worth a look further though...
]

When we swapped the SC auto, the LS still had the OEM final drive and even w/o the 4.27 it was STILL 200rpm higher. David helped me w/ the swap and rode in the car w/ the SC auto and both of us went "woah this doesnt feel like a stock ls anymore" haha. Not night and day change but off the line it felt like it lost 400lb, per say. I found the car to be a lot more fun w/ the mod.

Hope this helps some.

so on the cable, I assume you meant to adjust it so that it is as TIGHT as it will go, trying to fool the trans that you are putting in more throttle than you actually are?

The line pressure cable is used to vary ATF pressure thats used to engage the next gear. If you left it unhooked completely (very low line pressure), the clutches will spend a LOT of time slipping and this is bad news. After some abuse the clutches burn out from the friction. The article on the shims also addresses the line pressure and some buys just delete the cable altogether and "lock" the cable inside the valve body at full so every gear has as much pressure as possible

 

[stevechumo]

If you want a better shift off the line and keep the trans lasting longer, send the valvebody to have it modified and put the shift kit on. I sent mine to http://www.importperformancetrans.com/ and it made a big difference. It gets more jerky, but it's good for hi-performance driving, and it feels like a stick shift.

 

[spf_lexus]

steve, I have been doing a lot of reading on beefing up the a340 and the big problem I keep seeing is the stock sprag/cage setup. I know you had your v-body redone but are you having any issues w/ yours considering your high output?

The census on the supra forum was that the accumulators do the job well but its a guarantee the sprag or cage to fail when boosted on top.

 

[stevechumo]

Even though I didn't boost the car past 400 rwhp, I think the stock sprag gear will hold up fine for that kind of power and it should take a lot more power than that. I don't have any issue with the built tranny yet. Kind of hard to know unless I pass its limit. And no one knew of its limit yet.

The tranny accumulator mod is a good economy mod, but it's not a complete mod. It's just not increasing more pressure, it must allow the fluid to travel fast enough to where it should be. If the holes in the valvebody are small, increasing the pressure won't help much because the fluid is still stuck to where it currently is. I believe Khris is the one who modified the accumulators, but he eventually sent in his valvebody to IPT to be rebuilt properly.

 

[spf_lexus]

Thanks for the clarification Steve.


Im about to break in my 4.7L and realized it might be pushing thr trans once tuned. Im aiming for 400whp and maybe 500whp later if I get bored

At this point my SC is no longer legally streetable so I am saving for a daily driver so I will have time to play around with the auto rebuild.

 

[stevechumo]

Street or track is just in your mind. Slow driving = street. Fast driving = track. LOL.

 

[spf_lexus]

Slow driving = street. Fast driving = track. LOL.
__________________

LOL, i'm with ya on that one but right now this thing is LOUD and very obvious! I live in murrieta and the cops out there are all too bored and im used to being pulled over for no reason.


Its basically a stripped out racer. the dash is the only piece of interior left. I rhino lined all the metal. Single seat + 4 point harness. No cats, no mufflers... just 2 straight thru canisters. Loud procharger. prochargers are notoriously loud from the straight cut gears. Tial 50mm vented to atmosphere. And the list goes on lol.

To be honest I wouldnt mind taking it out on weekends for a quick romp but i do not know how I will get it to pass smog inspection. It would have to be an "under the table deal". Do you swap bak to OEM in order to pass smog steve?

 

[stevechumo]

If this car is for track racing, then you don't need to smog it. Just file with the DMV for an off-road car. If your car is in that condition, passing smog will still get you in trouble if you get pulled over. It's too obvious. Call me to discuss about smog.