LS4 Into an MGB

Scott Costanzo · December 17, 2014, 06:09:19 PM

Jim,
From what I'm reading, when you get to around 10 volts you start having difficulty firing the coils. The injectors seem to "fire" with a 9 volt battery so they may be more forgiving. A crank sensor signal is required for a start so I had a couple of issues going on. I'm anxious to see what it does once it gets into closed loop which won't happen until the cooling system is in place. Lots of details which is part of the fun.

74ls1tr6 · December 17, 2014, 08:56:13 PM

Scott, At minimum get your exhaust leaks taken care of between heads and 02 sensors. Its not as bad behind the 02 sensors to get it on the road, and get all the other stuff dialed in with the swap. That way your computer can do its job to keep it running smooth and idle right. Are you running a vss (vehicle speed sensor) sensor on your transmission? That can change idle once the cars starts to roll. Just some thoughts I went through.

Scott Costanzo · December 18, 2014, 07:42:35 AM

More good advice, thanks Calvin! Yes, I wouldn't even think about not using a VSS. I'm doing a home brewed one off the differential flange. Mounting it is one of those many small tasks that need to be done yet. I'll post some details about it when I get to it.

mgb260 · December 18, 2014, 08:24:41 AM

Scott, Your swap is quite an achievement! As far as I know, the first LS4 RWD with block mounted starter! Others will soon follow.

BlownMGB-V8 · December 18, 2014, 10:17:46 AM

Seems to me you'd be better with a VSS mounted to the driveshaft near the transmission as it would not be moving around all over the place like the diff will. But then I suppose it will be moving forward and back. And a cable speedo would mean you can't use the electronic plug-in at the tailshaft. I think there was a combo cable drive VSS pickup but have no further info.

Jim

Scott Costanzo · December 18, 2014, 12:40:45 PM

Jim N., Thank you, I really appreciate it!

Jim B., As always, I appreciate your input! The approach to mounting the VSS on the differential isn't my idea at all. A vendor, I think it was Jag's That Run, was offering a kit that used a GM sensor. I took their idea and did the same thing for my V6 swap. Ran that for almost 10 yrs. with no issues. I don't see any reason for changing the approach at this point. I've got it all wired up, just need to build the mounts. You bring up some interesting points though.

74ls1tr6 · December 20, 2014, 09:52:35 AM

Just a thought, I believe your VSS pulse is what an electronic speedometer uses. The Autometer speedo is what I have used, needs that pulse. I guess that is how your setup works too? Are you using electronic or mechanical speedo?

Scott Costanzo · December 20, 2014, 05:10:49 PM

Calvin,
I'm using the stock gauges so a mechanical speedo. The main reason I'm including the VSS is because the PCM needs to know if the car is moving or not. Another reason is I'll be installing factory cruise at some point so it will be needed there as well. I'll be using a 4 tooth "reluctor" and Sinister configured code to work with it. Actually, I believe the PCM needs the number of pulses that will be generated per mile with your rear end and tire size. Sinister Performance sends a fairly long questionnaire you fill out before he does your PCM. Both the sensor and "reluctor" wheel will be mounted to the rear end so the gap will be static if I do my job correctly and make the mount ridged enough.

Scott Costanzo · December 21, 2014, 10:30:04 AM

Kelly was exactly right. The header flange is warped. It bows out in the middle so the middle two cylinders are leaking like a sieve. Need to address that soon. Made good progress on the throttle pedal yesterday. I'll share it when it is complete. Here's a shot of how the starter fits. Been meaning to get one of it for a while and finally had the chance yesterday.

BlownMGB-V8 · December 21, 2014, 11:36:06 AM

On the BOPR it is possible to separate the port flanges once the header is made, which goes a long way to eliminate the warpage problem. MLSS gaskets are a great option if they are available.

Jim

kstevusa · December 21, 2014, 01:51:55 PM

Scott, The machine we used was a giant Belt sander (rather than a circular stone on a table). Course medium and laid the flange flat on the belt and removed material until the pattern was even accross the entire surface. Size- 2'W X 4'L- pretty large belt sander :-)

Scott Costanzo · December 21, 2014, 04:40:55 PM

QuoteOn the BOPR it is possible to separate the port flanges once the header is made, which goes a long way to eliminate the warpage problem. MLSS gaskets are a great option if they are available.

Jim, that's an interesting idea. I could split it in half but not into fourths because of the way the bolt pattern is laid out. I'm going to think on that one.

Kelly, I'll figure something out. I don't have access to a belt sander like that though. Thank you for pointing me in the right direction! How's that Jag doing? Can't wait to see it!

mgb260 · December 21, 2014, 06:35:53 PM

Scott, Maybe a hydraulic press to straighten?

Scott Costanzo · December 21, 2014, 07:23:35 PM

QuoteScott, Maybe a hydraulic press to straighten?

Thanks Jim! That's exactly what I was going to try next time I get out in the garage. Won't cost anything and won't take long do, worth a shot!

MGBV8 · December 21, 2014, 11:02:00 PM

Cut the middle two tubes, straighten flange, bolt flange to two full length pieces of angle iron, & reweld center tubes.

Scott Costanzo · December 22, 2014, 01:20:21 PM

QuoteCut the middle two tubes, straighten flange, bolt flange to two full length pieces of angle iron, & reweld center tubes.

Option #3. Thanks Carl!

We're talking about less that a 1/16" so I'm hoping the press will get it close enough.

Scott Costanzo · January 10, 2015, 10:26:22 AM

Have made some progress over the last couple of weeks but the holiday season and a very busy time at work did slow things down a little. I did get the throttle pedal/cable about 90% there and started modifying the transmission tunnel to accommodate the new position of the shifter. The transmission had to move rearward about 1.5" for the LS4 compared to the v6 position I had it in originally. I actually have to work today but hope to get something done on the car tomorrow.

My wife and I visited Artie and his wife during New Year's week and had a fantastic time! Many of you here know Artie. Anyway, a friend of Artie's, Dave, stopped by New Year's Eve afternoon with this:

Pontiac G8. Dave's a real cool guy. His car has an LS2 that he put headers, a CAI and a tune on. It puts out about 375 HP to the rear wheels. I realized after thinking about it that I had never been in an LS car before so it was a real treat. He took us out on some back roads and I actually got to drive it too! It really moves that big car quite well and sounds great! It was interesting to get a little perspective on what to expect. He's putting out at least a 100 HP more than I will be but my car weighs almost 2000 lbs. less than his. Should be interesting.

MGBV8 · January 10, 2015, 10:35:54 AM

Donor car!

Scott Costanzo · January 19, 2015, 08:58:11 PM

I thought I would do a quick update. Lots of little things are getting there. No pictures unfortunately but will do several next time I get out to the garage. I mentioned last time that the throttle pedal is just about there. I also have the transmission tunnel mods done except I'm waiting on a rivet nut to arrive to finish it. Today I got the VSS reluctor done and am very happy with the way it turned out. The sensor mount is underway and it should be completed next time.

Almost forgot to mention I managed to get the passenger side header straightened out. Used my press and slowly inched my way there. I also took Jim Stabe's advice and got a set of the manifold gaskets he recommended. They're pretty thick, looking forward to installing them. Need to check the drivers side as well.

As everyone who has done this before knows, all these little things are very time consuming. I spent about 3 hours on the reluctor alone. It's stuff that has to be done. Inch by inch!

mgb260 · January 20, 2015, 12:09:09 AM

Hey, You're getting there Scott!

Scott Costanzo · January 30, 2015, 02:54:15 PM

Thought I would give another small update. Things are still proceeding and progress is being made but the project is at the point where it's hard to notice much change from week to week. There are lots of little details to take care of with each task.The challenge is to keep pushing forward and not let the lack of visible progress make you feel like the project is in the doldrums. I've been doing fairly big projects on the car (nothing like this) during most of the last 10 winters and this is always a challenge for me. Once I start getting some of these small details out of the way more visible things can be completed. Further complicating things is it looks like I won't get my garage time for the next couple of weeks. Too much going on outside of the garage at the moment.Typing it out helps give it some perspective.

So, here is some visible progress that has been made. As you'll see, there are still quite a few little details to take care of with this task as well.

LS4ThrottlePedal (1).JPG

This is what I'm doing with my throttle pedal. The angle is kind of bad in this picture but heel and toe should be much easier when this is complete. There is actually quite a bit of adjustment available. I want to make sure the throttle pedal is lower than the brake pedal and as far away from it as possible. The pedal is from a mid-90's Toyota Corolla. The cable is from a 2000+ Cadillac w/Northstar motor. The following pictures show additional details at the throttle body and through the firewall.

I'm currently working under the car on mounting the VSS to the differential and running my battery kill switch and ground cable. I'm trying to get that completely done before moving on to other tasks. One of the things I can do over the next couple of weeks is some additional detailed planning/thinking about the remaining tasks so I can try to be more efficient and also to avoid forgetting too many things.

BWA · January 30, 2015, 05:28:13 PM

Keep pressing forward Scott, progress is progress whether it is incremental or in great surges!!
I am looking at the steep angle the throttle cable makes as it transitions from the end of the sheath over to the throttle cam. I think you should try and make the angle a little less as you will get the cable wearing out from friction.

Cheers
Byron

Scott Costanzo · January 30, 2015, 06:56:44 PM

QuoteKeep pressing forward Scott, progress is progress whether it is incremental or in great surges!!
I am looking at the steep angle the throttle cable makes as it transitions from the end of the sheath over to the throttle cam. I think you should try and make the angle a little less as you will get the cable wearing out from friction.

Thanks for the feedback Byron. Yes, I plan on heating the cable end with a heat gun and angling the cable housing to lessen the angle a bit. It's too sharp an angle now but not quite as bad as it might appear in the photo,

You're right, every minute spent doing something is one minute closer to finishing.

BWA · January 30, 2015, 08:30:20 PM

Scott I know you are a busy man with other priorities, when you get time could you please give your audience some instruction the following things:

I am sure that the LS4 engine had a drive by wire throttle body, what throttle body did you go with?

If the original throttle body was drive by wire could not a person stay with drive by wire and use a generic drive by wire gas pedal that you can buy from a hotrod shop? If this is possible could a person reuse the ECU that came with the LS4 and get it to work?

If you using the original ECU with another throttle body that runs off a cable how does one deal with the programming issues related to the drive by wire code in the ECU? Does the programmer just disable this code?

Take your time and give us answers on these issues when you get time. For us your conversion project is the beta version!!

Cheers
Byron

Scott Costanzo · January 31, 2015, 11:44:43 AM

QuoteI am sure that the LS4 engine had a drive by wire throttle body, what throttle body did you go with?

If the original throttle body was drive by wire could not a person stay with drive by wire and use a generic drive by wire gas pedal that you can buy from a hotrod shop? If this is possible could a person reuse the ECU that came with the LS4 and get it to work?

If you using the original ECU with another throttle body that runs off a cable how does one deal with the programming issues related to the drive by wire code in the ECU? Does the programmer just disable this code?

Byron,
Thanks for the interest in the project. I seriously looked into using the original PCM when I was planning this project but decided it wasn't the way to go for a variety of reasons. From what I'm reading, it isn't as simple as getting an off the shelf DBW pedal as you are suggesting. There are several different OEM pedals and in many cases they do not interchange. I'm not sure how an aftermarket pedal would fit into this equation. The usual recommendation is to get the PCM, pedal and TAC box, if needed, with the engine from the same car.

In most cases, it isn't possible to use a DBW PCM in a DBC application. The components used to drive the IAC are usually not included on the circuit boards in DBW PCMs. Hope this answers your questions.

You seem to have a fixation on the original LS4 PCM, what's up with that?