skirkland1980 Posted April 22, 2012 Share Posted April 22, 2012 Hello. I just finished installing a 700r4 in my 1983 280zx turbo. I went with a 2000rpm stall converter. It feels sluggish now. I know the 700r4 is about twice the weight as the jatco L3n71b that was in there. My question is, would more stall help. Anyone running a similar setup? I'm estimating about 300hp at the flywheel(s)(it has 2 flywheels now lol) The engine has a custom intake with a t3t4 turbo and .82 hot side. Quote Link to comment Share on other sites More sharing options...
rejracer Posted April 26, 2012 Share Posted April 26, 2012 define "It has 2 flywheels now lol" You didn't bolt the converter to the flywheel did you? What diameter converter are you running? A good 9" or smaller will really wake it up. What are you using the car for? What cam are you running and where does the power come on with your setup? What RPM's are you running, and what do you want your top speed to be? All of the above are factors in converter selection. With the above it's possible to suggest possible diameter, stall and STR for a converter. -Robert Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted April 28, 2012 Author Share Posted April 28, 2012 The converter is a b&m part # 70420 http://www.summitracing.com/parts/BMM-70420/. It has the stock flywheel/flexplate for the L28 then and adapter to bolt a SBC flexplate to that. I drive the car often on the street and drag race occasionally. The engine internals are all stock. The only things I've changed that should effect powerband are the intake and turbo. Boost peaks around 3500rpm. Thanks for the help. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted April 28, 2012 Author Share Posted April 28, 2012 Here is the adapter for the flywheel Quote Link to comment Share on other sites More sharing options...
rejracer Posted April 29, 2012 Share Posted April 29, 2012 I'm going to say the stall is too low for your application. V8 converters measured stall based on an engine that is approx 300hp street build, in other words a torquey 300hp. From the converter guys I have talked to this is a very subjective measurement. I don't know your level of converter knowledge, so I'll explain, forgive me if this is basics for you. If you have a 2000 rpm stall converter and put it behind a 150 hp engine and a 400 hp engine then the engine will stall out at different rpm's The purpose of the stall on a converter is to allow the engine to rev so it can get in it's powerband. 2000 stall is considered a low stall for V8's Your 6cyl turbo sounds like it could use a higher stall. If you can put the car in drive and floor it where do the rpm's level off at? If you are below 2000 stall then you have less torque at low rpm's than that converter was tested with. Use this offset when ordering your next converter. For example if your engine stalls out at 1600 rpm you now have a 400 rpm offset. If your turbo spools at 2500 rpm then I would go with a 2500+400=2900 rpm stall converter. If you end up buying a new converter, you might check out edge converters. Fill out one of their forms with your vehicles info and they will make suggestions. I am currently running one of their converters in a 94 impala, and I love the responsiveness, but don't really care for how loose it is on the low end. The folks at edge can help you through the decision making process. Hope that helps. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted April 29, 2012 Author Share Posted April 29, 2012 Yes. It's helpful. I figured I needed more stall than stock I just didn't want to over do it. Thanks _ Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted May 3, 2012 Author Share Posted May 3, 2012 Well I've been trying to decide between 3000 or 4000 stall. Would 4k be too much? It'd be nice to be able to build some boost before launching. With the old trans I was able to build 1psi. Now 0psi. At least with TC lockup I can maintain my fuel economy on the highway. Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted May 3, 2012 Share Posted May 3, 2012 (edited) DO a 4K. You won't regret it. It will be an absolute animal,and if you have lockup, whats the big deal? Don't go cheap though. Go with a precision industries or yank converter. Expensive yes, but they each give you a free re-stall, and they won't come apart and damage your trans. Even one with a documented fresh re-stall would be good. The PI vigilantes run a bit loose, as do the yank PT's. The yank SS's are about spot on. For reference my vig 4000 would actually flash to 4400. MAN would that thing get you moving. HOWEVER 4K might be a bit much on a turbo car. SO, you might be happier in the 3K range. IDK, that's just LS1 fbody knowledge dripping out. Edited May 3, 2012 by SUNNY Z Quote Link to comment Share on other sites More sharing options...
rejracer Posted May 4, 2012 Share Posted May 4, 2012 If you care about street manners go with the 3k. Also just as important is to specify the STR (Stall Torque Ratio). Basically Stall is the low end efficiency. Stall Torque Ratio is the ratio of input torque to output torque, and is mostly noticeable in higher rpms as efficiency is reduced up there. An all out drag car with a high stall high STR converter is not drivable or safe on the street. My analogy above is not perfect, so take it with a grain of salt. My suggestion is to read up and of course call Edge, PI, and or Yank and ask them so you can know what to expect and order the right converter the first time. Just bear in mind when getting into the world of slush box racing, it's even more important to match engine power band, to the converter, to the trans gearing, to the rear end gearing. PI and Yank converters are very good, but only necessary if you are running in excess of 400 or higher HP. The Edge converters are cheaper because they run a lighter housing, so if you don't have monster hp/torque it may be a better choice. Quote Link to comment Share on other sites More sharing options...
Bernardd Posted May 4, 2012 Share Posted May 4, 2012 The converter is a b&m part # 70420 http://www.summitracing.com/parts/BMM-70420/. It has the stock flywheel/flexplate for the L28 then and adapter to bolt a SBC flexplate to that. I drive the car often on the street and drag race occasionally. The engine internals are all stock. The only things I've changed that should effect powerband are the intake and turbo. Boost peaks around 3500rpm. Thanks for the help. Where does your boost start to come on? IE: positive pressure rpm I run a stalled Jatco and I had mine stalled to where positive pressure starts then with a transbrake it builds all the boost I need get a boosted launch. What kind of times are you running? Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted May 4, 2012 Share Posted May 4, 2012 I agree with the above statements. Again, this is just my experience with LS engines talking. Its a whole different game with you L series boys Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted May 5, 2012 Share Posted May 5, 2012 Does a TH700r4 default to 2nd or 3rd gear when a sensor or switch input is missing? Many transmissions do. Definately count your gearshifts. What is the rear end ratio? Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted May 12, 2012 Author Share Posted May 12, 2012 Well I'm upgrading the stall sooner than I thought. My flexplate is broken. I got a 10" converter from summit and I'm returning it because the craftsmanship on this converter is very poor. I'm going to try the hughes. Here is a video of the broken flexplate. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted May 14, 2012 Author Share Posted May 14, 2012 I figured out why my flexplate broke. It's because the transmission is slightly off-center. I'll be picking up some offset dowel pins from Summit tomorrow. I also found that there are some differences in flexplate offset so I also returned the summit flexplate for a pioneer flexplate which is a much better fit. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted May 30, 2012 Share Posted May 30, 2012 There was an article in "hot rod"/"car craft"/"Popular Hotrodding" around 1981 titled "off center casualty" that dealt with this exact issue. Wish I could find it. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted June 5, 2012 Author Share Posted June 5, 2012 Well the offset dowel pins didn't move the transmission up enough so I'll have to get a new adapter plate fabricated. That might take a while since it's kind of expensive to do and I'm low on funds. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted August 7, 2012 Share Posted August 7, 2012 If your adapter plate is 1/2" then you might want to contact Warren. He can provide a whole kit for mounting a Chevy/Buick/Pontiac auto behind the L28 - CNC'd adapter plate. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted August 24, 2012 Author Share Posted August 24, 2012 Mine needs to 3/4 because of the thickness of the center hub. I ordered a new piece of aluminum in early july and took it to my cnc guy and finally got tired of waiting. I picked up my stuff and bought a giant band saw and borrowed a drill press and built a new one. Here it is. The car should be done very soon now. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted October 30, 2012 Author Share Posted October 30, 2012 I almost forgot to update this. I got the car back together with the hughes 3000 stall converter and it's wonderful! The car is very quick now with no slipping 2nd gear. Thanks for everyone's input. Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted November 2, 2012 Share Posted November 2, 2012 Glad to hear. What brand TC did you go with? What STR? Quote Link to comment Share on other sites More sharing options...
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