Jump to content

86 RX7 with Turbo LM7 and Megasquirt


Recommended Posts

I took the car for a drive last night, but it was a real short one. The driveshaft is binding so I have to re-check the angles again. I thought they were OK, but I guess not.


I'll check it out tonight and start tuning.


The thing is a beast for sure, I barely touched the gas in reverse and left two trenches in the dirt about 6 feet long. Yeah traction, I have none.




OK, next update:


I got the driveshaft problem fixed good enough for now. I shimmed the tranny up a little bit. I drove the car a little bit with no tuning, didn't get after it at all until I tune. I installed the bung for the wideband sensor. My cooling fan is working well, controlled by megasquirt. My dash tach is working, also controlled by megasquirt. Water temp gauge is working in the dash. The oil temp in the dash does not work, so I have a cheapo summit oil gauge installed for now. I got my heat shield on to protect the fuel lines under the car. Also got a quicky heat shield to help protect the megasquirt while it is in the engine compartment.


I made a list of things to keep an eye on. One being the .040" clearance between the oil pan and steering rack. I have various things going on, mostly small stuff. I don't have any leaks and so far the car doesn't act like it has any steam/coolant heating issues.


I orderd the knock sensor interface module for megasquirt today to help with tuning. I talked with the guy that makes the module and he says it will work with the two LSx knock sensors. He also sets it up based on the cylinder bore which is 3.779 for the 5.3


Tonight I plan to work a bit on tuning the fuel and spark. I am also working to get insurance and plates on the car. Mainly so I can tune on the street, I live wayyyyy out in the sticks with plenty of unused roads to tune on.


Then the last thing I have to sort out is what tire to run at the dragstrip. I see that the 26x8.5 slicks work on the stock rims, but $300 for them and $100 for tubes?


Also, I have the pinion snubber, but have not installed it yet.


Otherwise I think I am just in the tune/troubleshoot phase now. Still targeting August 10th to hit the track, but I may not have tires sorted out by then, so it may be a traction limited track night.

Link to comment
Share on other sites

  • Replies 87
  • Created
  • Last Reply

Top Posters In This Topic

I got plates and insurance on the car. I also got the pinion snubber installed.


Started tuning on the road and found out that I am not getting a clean trigger signal to the Megasquirt from the LSx crank sensor.


I tried a couple quick tests from my past experience with megasquirt, but still the same behaviour. I am going to put a scope on the signal tonight and see what is happening. It is very likely that I am getting noise coupled into the crank sensor wire. I don't have it shielded right now and I placed megasquirt right next to the pssgr side coils.




I think I found my problem with the trigger input to megasquirt not being steady, but I have to test the fix tonight.


I was powering my LSx crank and cam sensors with 5 volts, they are suppose to be powered with 12 volts. I have been emailing dieselgeek to try to figure this out and it came up that I was using the wrong voltage due to an assumption on my part. Typical megasquirt stuff.


Well, it drives pretty nice, I had to fix a couple places where my exhasut was hitting the body. The power steering rack is capped off, but it didn't seem too bad using armstrong :)


The problem is that I still didn't get that crank sensor trigger cleaned up to the megasquirt, so it is like running on 7 cylinders. Still enough to dig trenches all the way up my driveway. But I can't finish the tuning until I fix this. I am still a bit perplexed. I got a good scope on the system and everything checks out OK so far. Maybe a bug yet with the code since the LS1 mode is new and AFAIK no one is running the new code version on an LS1 to confirm. Maybe coupling noise on the crank sensor wire, but I doubt that because I see problems just during cranking with the coil and injectors disconnected.


I'll keep plugging away at it, bound to fix it sooner or later. If I don't get to the track in August there is a US performance series race on October 14th and a real street race on October 13th, so I'll shoot for those.


I have had some problems in the past with megasquirt installs that took a while to iron out, but for the most part I have had really good luck with it. Might just be my turn in the barrel :dunno:


I have been through a ton of experiments and I think I got it figured out. The newest addition to the megasquirt code for the cam sensor input is not working as advertised for me. No one else has confirmed it works yet, so I am just going to build a small pulse generator circuit to bypass this problem. The pulse circuit has been confirmed by other people. So with any luck tonight or tomorrow I will have it running 100% and finish tuning.


Definitely going to be updates to the megasquirt notes once I confirm this works.

Link to comment
Share on other sites

Fixed 3 things and now I get steady rpm and the car is running pretty good. I am working on tuning now. I updated the settings in this thread to reflect what I found.


1. I had a bad opto transistor, it finally quit all together.

2. I had some settings wrong in megatune.

3. I had a bunch of higher frequency noise all over my MS setup. I added bypassing caps to the following wires on the relay board (.01uF and .22uF): battery 12volt, switched 12v, crank sensor input, cam sensor input, injector bank 1 control, injector bank 2 control.


Now I am going to install the knocksense module to monitor while tuning.


Also, I get a little bit of popping out the pipe at about 80kpa and 2000rpm. Could that happen if I'm too rich, it is definitely rich right now as I am just starting tuning. I've got the wideband on it. That popping concerns me a little, but it only does it in that one spot at about half throttle. If I go WOT it doesn't do it, but I haven't looked over the log files yet.


I am going to continue tuning and cleaning up little things this week and take the car to the track in Pueble this Friday. It might not be much to see at this point unless I get a lot of time to tune on it, but its starting to run and this is the last test and tune.


Two pretty funny things from my wife, she was riding with me helping watch some things on the laptop. I am telling her that it just doesn't feel like its running that good, then I take off in 1st up to about 4K and ratchet up to 2nd. The car throws us back violently and burns the tires a bit. She looks over and says: "And you don't think its running good?"


Then I try a little launch, stock converter so I stall it at about 1100-1200 and let off the brake while mashing the throttle. From the passenger seat I hear "Woh". I asked her if she wanted to tune while I drive or if she wanted to drive. She said she would drive

Link to comment
Share on other sites

There is only one smiley that fits for last night: :owned:


Yeah, I decided to see how the engine runs now on 8 cylinders. Thats right, the last two weeks it has been running on 7. Now that I got all the computer signals cleaned up I noticed #2 was not firing(it would fire about 10% of the time). Changed the plug and the engine runs perfect now. That was also causing the popping out the pipe. Now it runs 100%, and the transmission isn't liking it. Feels like it is slipping. I'm going to get a pressure gauge on it and make sure the TV cable is adjusted correctly and go from there. The wife was with me again and now she knows what it really runs like :D I told her it wasn't running right, but I hadn't done any tuning yet so I kept dismissing the engine miss. Track this friday if I don't break it and if I can get the tranny to work.

Link to comment
Share on other sites

I got the TV cable setup adjusted better. For one thing I was only getting about 75% throttle. I fixed that and then re-adjusted the throttle body cam for the TV cable, then adjusted the TV cable itself. Now it switches gears from 1st to 2nd around 4800rpm and the car just fishtales. I haven't done any fuel tunng yet, it is 10-11 across the board at WOT. Also I have the timing set 2 degrees below a stock high octane map. So there will be plenty of room for improvement in fuel and spark tuning, but I can't get very good traction already.


My back tires were bald so I went this morning and got two new cheapo street tires for the back. I will get some slicks going in the next couple weeks, but after all the work I just want to get out and play a little.


I going to try to get the fuel map more around high 12's uner WOT tongiht and tomorrow then load it on the trailer and see what I learn at the track.


Next on the list will be a camshaft and valve spring change, torque converter and slicks.


Its starting to get fun now!!


You guys probably saw my trip to the track post. The 700r4 and the street tires were a dissapointment. I am getting a powerglide built locally for the car and putting slicks on it, then head back to the track. I am also swapping in the Z06 cam and springs. I got those ordered last week to raise my rev limit from the stock LM7 cam. I picked that cam because it will work well with the turbo for now. I am still not planning to start any of the turbo install until the car gets down the track good with glide/slicks/new cam.


At least this way I'll pick up a converter/trans brake and good transmission. Then I think I will only have to worry about how long the stock NA rear end lasts.

Link to comment
Share on other sites

I am officially finished with the 700R4. I tried adjusting the pressure with a gauge and made sure the TV system was set up properly, but it still won't shift. I knew the 700R4 would not carry me to my final goals, so its finished.


I dug out my powerglide core and I'm taking it to the builder tomorrow.


I also picked up the ford 8.8 rear axle this weekend. 3:55 posi from t-bird.


For my goals I decided I will go ahead and install the glide, granny's 8.8 kit and 10 point cage this winter. I will also put driveshaft loop and tranny shield in. I can't remember if the granny 8.8 kit has the loop built in?


If I can sell a couple more parts I should have the money to also complete the turbo isntall this winter since it looks like my original goal of running the car a few times non-turbo is going out the door because I'm running out of track time this year.


EDIT: as you can see this car is pretty much becoming a purpose built drag car. I will keep it street legal as long as possible, but I don't see it as being a daily driver car in the end

Link to comment
Share on other sites

The shop tore down my powerflide core and said it looked good, so now they will build it up.


I only need injectors, new fuel rail and an external wastegate to complete my turbo parts.


I also picked up the FB lower links and watts linkage for the 8.8 install. Now I just need to save the money to order the granny's kit and new axles.


I am going to start with 7psi boost and no intercooler. Once that is set up and running good I will decide my next move.


I know I always get lost reading other peoples build threads so here is a quick re-cap.


What I am working towards: (in case anyone lost track)


LM7 engine with LS1 intake/LS6 550 lift cam/LS6 springs (stock internals)

76mm turbo (start with 7psi and no IC)

Built powerglide with brake and high stall converter(haven't picked stall yet)

Megasquirt EFI, LC-1 wideband, Knocksense module

New injectors, New fuel rail

8.8 granny's solid axle



I ran the car at the track with:


Stock LM7 with stock cam (LS1 intake, stock injectors, stock rail)

Megasquirt EFI, LC-1 wideband

No turbo

Stock FC rear end

700R4 tranny (wouldn't shift to 3rd)

Street tires (big mistake)

Link to comment
Share on other sites

Once it runs with 7psi then I will at least crank up to 14psi with intercooler. After that it is just who knows.


I have 150# injectors setting around from a different project. I am thinking of running them if I can get it to idle. I will have to add a second fuel pump when I go above 7psi, that will be at the one pumps limit.


I run 18psi on my Talon. I would love to see that on the LM7 engine.



Ok, got an update. I picked up my built powerglide with transbrake and 4000 stall converter last night from the shop. I got a great deal on the converter because another guy had it built for his drag car and the stall wasn't as high as he wanted. I will have to check it for sure but it is suppose to be between 4000 and 4200. That should be a great starting point for my turbine housing size and camshaft. The shop put the stainless TH350 input shaft in my glide and that is how this converter was set up, so lucky timing. Otherwise I was going to get a converter built locally, but the price of that was much much more.


I am saving money for the granny's 8.8 rear end kit now. Once I have that I will be pretty much set up.

Link to comment
Share on other sites

I've been away for a while gathering parts. Some of these I already had but I thought it might be neat to get a pic with everything together.


76mm turbo

T6 weld flange for the turbo

60mm external wastegate (SS cheapo)

High flow fuel rails

150lb injectors (there is a story behind these because we all know I don't need injectors that big)

550 lift Z06 405hp camshaft

Valve springs, locks and retainers for the Z06 camshaft

truck exhaust manifolds to point forward for hot side turbo piping


Also tossed in a pic of the built powerglide with transbrake and 4200rpm stall converter





Link to comment
Share on other sites

  • 1 month later...

Ok, finally saved up enough money for the ford 8.8 torque arm solid axle kit from Grannies. Just got off the phone with Grant and the conversion kit with caliper brackets is on order. I have the t-bird 8.8 diff already. The only thing left to order is new axles.


Here is the pic from their site:



Link to comment
Share on other sites

  • 3 weeks later...

Got some work done on the car over the holiday break. Got the powerglide and 4k converter installed. Got the z06 550 lift cam installed, new springs, new timing chain. Installed turbo oil drain fittings on both sides of the oil pan for flexibility. I will only use one of course, but wasn't sure which side I would be mounting the turbo when I installed them.


I am waiting on the 8.8 granny kit to arrive and I will be installing that next.


In the meantime I spent about 4 hours working out the trubo install plan and here is what I came up with(I am really happy with the way it is going to work out):


Put the turbo on the drivers side where the battery use to be(move battery inside passenger compartment). The turbine inlet flange is then out where the alternator use to be(move alternator to passenger side). There is a lot of room in this area to merge the hot pipes and mount the wastegate. The charge outlet points straight down and goes through the sheet metal below where the battery use to be. The charge pipe runs in front of the radiator and comes back through by the passenger headlight(great for adding FMIC). This keeps the charge pipe out of the engine compartment to help congestion. Passenger hot pipe goes below the water pump inlet and across below/between the lower pulley and electric fan. Driver hot pipe leaves enough room for the 3-3.5" down pipe from the turbo to exit the drivers side of the engine compartment. Heat shielding for wiring harness and brake booster/MC. New fuel line down passenger side of car to stay away from exhaust. Remove driver headlight and cut sheet metal for cone filter on inlet of turbo. Turbo oil feed from tapped spot above oil filter(OEM oil cooler location). Turbo drain to ½†fitting installed in oil pan 1 3/8†below top of oil pan. Flex coupling between hot pipes. Mount for turbo. This leaves room for radiator hoses, electric fan, alternator mount on pssgr side, downpipe on driver side, etc. Start by using 2.25†dia hot pipe for each side (this is still as large as the truck manifolds).


Losing the driver headlight is not a big deal for me since I don't need it at the drag strip, only need one headlight.

Link to comment
Share on other sites

Pics from the weekend.


First, the 8.8 install so far:


Got the 8.8 prepped by cutting off all those factory brackets and grinding the welds




Then welded the granny's mounts for the lower links/shocks and watts link.




Stock rear removed.




That was the hard parts as far as I'm concerned with the 8.8 install. I did remove the seats and carpet for the next step which is isntalling the hockey pucks and front lower link mounts. I'll get more pics when the torque arm and caliper brackets are installed.


Second, the turbo install so far:


Driver side front with wiring removed.




Driver front after cutting the sheet metal to allow for the charge pipe and inlet air filter. I know some people won't be willing to do this for a turbo install.




Top view, the radiator will move towards the pssgr side a inch for clearance of the upper radiator hose. I will rewire the front of the car so the harness no longer goes below the turbine along the driver frame rail.




This picture is weird with the angle. The turbo really sets down even with the radiator support. There is plenty of room for the air filter.




One last view through the front.



Link to comment
Share on other sites

  • 1 month later...

A couple new pics for you guys. Got the turbo mounted on the drivers side. Got my new fuel rails and injectors installed. Switched to truck round coils becuase they mount higher on the valve covers for clearance with manifolds flipped upside down. Also used two driver side valve covers, easier crank vent that way. Still have to finish putting the wire harness in loom, but its getting there. Notice that I moved the relay box back behind the strut tower.


4 inch downpipe is in there. Started the FMIC piping. I removed the stock fuel lines and vent line. I'll run new ones now on the pssgr side of the car now.


woo hoo, starting to get excited. All of the sudden I feel like I'm on the downhill slope. :yay:





Link to comment
Share on other sites

Passenger side mounting of the alternator. I used a timing belt idler pulley from my bucket of parts. I think it cam off my Camry. It is wider than I needed, but it works good as the proof of concept.



Another view of the alt mounting.



Upper IC pipe.



FMIC, I have some concerns with this, but I'll see how it works.


Link to comment
Share on other sites

  • 2 weeks later...

The 8.8 install is completed.



More pics from the weekend:


Went back through the wiring and combined the harnesses



Interior, still stock



Transmission cooler electric fan, since I have the trans brake



8.8 installed, watts link, rear is hanging all the way down in these pictures



245/50R16 Drag Radials for testing purposes



300zx NA wheels


Link to comment
Share on other sites

  • 2 months later...

cut a hole in the airdam to fix cooling with the big FMIC blocking the original flow.





Mocking up location for the odyssey battery.



Couple pics of the 8.8 sitting on the ground.





I got my oil drain line installed on the turbo. I finished all the hot pipes last week and went to install them last night but realized didn't have a T6 turbine inlet gasket. I put that on order.


Last things to fire up:


1. Install plug wires

2. Connect fuel lines to rail/FPR

3. Install battery tray

4. wire dropping resistors for injectors

5. connect wideband to megasquirt


I have not installed the wastegate on my hot piping yet, but I am going to fire it up and test a few things first. Then I'll get the WG installed. There is no danger of accidentally building too much boost with this setup during testing.


Here you can see how the flex joints are installed for each side of the engine. The pssgr pipe goes low under the pulley, the driver side goes up and then down the front of the engine. Both sides use the same type of stock stainless manifold, I bought two sets to get two matching pieces. I don't remember mandrel pipe loosing much flow at all on a 180 bend like you see in the pictures. I am waiting on the T6 gasket and then I'll snap a couple pictures of how the pipes route inside the engine bay.





Link to comment
Share on other sites

  • 1 month later...

I started and drove the car on June 7th, then went on vacation for a week.


Got back and drove the car again on June 14th. Then basically let the car sit for a couple weeks while I caught up on other house projects. Went out to start it for my dad so he could check it out, rev'd it twice and it just died. I am not getting a crank signal to MS. I borrowed a scope from my friend today and will try to get it running again this weekend. I have not installed the wastegate yet. It is building boost around 3500-3800 rpm. The car sounds awesome with the Z06 cam. It surges at idle like a blown monster truck engine because the injectors are too big. So a little more work, but it is darn close now. I need a BOV. I alsoneed a second fuel pump so I can move to E85. Hoping to see it make around 700hp at 14psi on E85.

Link to comment
Share on other sites

  • 2 months later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...