1987 IROC Camaro Pro-Touring Build

[garage_engineer]

Alright finally back with another update.

Installing my torque arm turned into a bit more of a project than I thought it would... as most things do!

First, the failure analysis. My old torque arm was a 2-piece design with one end attaching to the rear axle and the other end bolted the transmission crossmember. The 2 pieces slid into eachother so the arm could shorten and lengthen as the suspension cycled. My torque arm broke right at this joint between the 2 parts of the torque arm when a collar broke off. This torque arm was old, so my guess is it was on it's last legs anyway, and the stress of autocrossing and high RPM shifting was the straw that broke its back. I'm just happy it happened on a closed course and not on the highway where I would have been stranded.





I ordered my new torque arm from UMI. They have 2 options, a longer one that attaches near the transmission and a shorter one that attaches to a dedicated crossmember you can weld in. I chose to go with the longer one that attaches to the transmission crossmember. The issue for me, however, was that my old crossmember used a bolted joint where my new torque arm uses a bushing. So, I started the search for a new crossmember!

There were only 2 options I came across that would accommodate my T56 transmission and a bushing mounted torque arm: One from BMR and the new Hooker LS-swap crossmember made by Holley. I ordered both to give them a try.

I tried the BMR crossmember first since it showed up first. Everything bolted up pretty well, but man does it hang low! It was by far the lowest thing hanging below the car, including the exhaust and subframe connectors. This might be ok for a car with stock springs, but for my car that's lowered 2+ inches I could just see this thing scraping on every driveway and speedbump:





The Hooker crossmember showed up a week later and I noticed right away that it would be far from a bolt on job. This crossmember is made for LS-swapped cars using Hooker's matching engine mounts that move the engine out of the stock position for better space under the hood. My car still has a small block, so the engine is in the stock location. It was clear this thing was going to require some "tweaking" to fit. The good news was that it sat WAY higher up in the chassis and if I could get it to fit the ground clearance would be awesome.

So, I had a decision to make. Keep the BMR crossmember which is an easy installation but hangs down low, or dive into modifying the Hooker one and have great ground clearance if I could get it to work. I chose the hard path!

There were 3 big modification I had to make to fit the Hooker crossmember in my car. The frame holes all lined up great, but I had to modify the mounting holes for the transmission bushing:


Next, the mounting bracket for the torque arm bushing sits really close to the transmission tunnel, so I had to trim back my heat shielding to make space:


Finally, that same bracket for the bushing was hitting against a threaded boss on the tailshaft of the transmission, so I had to trim that back a bit:


After all that, I was able to get it all bolted up in place and am really happy with it. Super sturdy piece and tons of ground clearance:


Torque arm bolted up and pinion angle set:


Big difference from the old piece!


While I was at it, I also ordered some lower control arms from UMI and their relocation brackets. I had been running some old, non-adjustable Hotchkis ones that came with the car. Without the relocation kit, they were at the incorrect angle with my car sitting at ride height (angling up towards the rear) so I was looking forward to making this upgrade to help with some forward bite. I ordered the control arms with UMI's roto-joints, which are Delrin bushings that provide a super tight feel (zero deflection) without the squeaking you'd just with a rod end. Super easy install compared to the transmission crossmember!






Finally, I got around the installing my racing seat as well. I had bought this seat before the UMI autocross in July but just ran out of time before I could get it installed. The seat is a Cobra Imola and it's FIA certified, which was important to me for safety reasons. I'm using brackets from a company called Planted combined with the side mount brackets from Cobra. The seat is sitting super high right now, so I'll need to do some tweaking in the future. It feels AWESOME though once you're out driving... huge upgrade in driving confidence!






That's all for tonight!

[SSLance]

Nice upgrade on the TA, that piece should work and last a lot better than the old design.

[mikels]

Having worked on PowerHop for the 2nd gen CTSV and and creating a couple patents for the solution, this is the only torque arm I have seen that correctly addresses the reaction loads for both acceleration and braking for torque arm rear suspensions.

https://www.unbalancedengineering.com/Camaro/TA/

It did not make it into production, but also developed a torque arm for independent rear suspension vehicles as well - combined with asymmetric 1/2 shafts eliminated all PowerHop under all conditions (high / low mu).

https://pdfpiw.uspto.gov/.piw?PageNu...%3DIN%2Fmikels

https://pdfpiw.uspto.gov/.piw?PageNu...%3DIN%2Fmikels

Dave

[garage_engineer]

Originally Posted by mikels

Having worked on PowerHop for the 2nd gen CTSV and and creating a couple patents for the solution, this is the only torque arm I have seen that correctly addresses the reaction loads for both acceleration and braking for torque arm rear suspensions.

https://www.unbalancedengineering.com/Camaro/TA/

It did not make it into production, but also developed a torque arm for independent rear suspension vehicles as well - combined with asymmetric 1/2 shafts eliminated all PowerHop under all conditions (high / low mu).

https://pdfpiw.uspto.gov/.piw?PageNu...%3DIN%2Fmikels

https://pdfpiw.uspto.gov/.piw?PageNu...%3DIN%2Fmikels

Dave

Interesting stuff Dave, thanks for the info!

[garage_engineer]

Been putting some miles on the car since I last posted about a month ago. My goal has been to see what's working and what's not and the things I need to address over the winter.

A couple of big things that have been standing out to me are that the car has a pretty big oil leak, and I need some new seat mounts! I have narrowed down the oil leak to either the back of the intake or the rear main seal. I'm planning on taking the intake manifold off this winter anyway (more on that below) so I will check that first before I pull the transmission. I put a new rear main seal in while I had the engine and transmission out, but it's definitely possible I damaged it while trying to stab the input shaft into the back for the crank. I'm tired of having a puddle on my garage floor every time I park it!

For the seat, I need to find a way to lower it and to get it on adjustable rails. It's just too hard to get out of the car right now which really hinders the car's every day useability. Once I'm in, the seat feels great and fits me well but I just dread the circus act it takes to get out of the car so I'll definitely have to address that.

The big decision I'm working on right now is what to do with the engine computer. The car right now runs well, but there are big "holes" in the rev range where the car will fall on it's face and then pick back up and take off. Again, not a big deal on the track where most of the time the engine is at 4000 rpm+, but it affects how the car feels around town. I really like crisp throttle response and I want the car to take off when I punch it at 2500 rpm. I've gone from a huge 58mm throttle body down to a stock one which helped throttle response a bit but still nowhere near where I'd like it. Right now, I have a stock ECU with a stock chip in the car. The small block in the car has a ton of upgrades including big aluminum heads, a cam, intake, headers... you name it. I don't think the stock ECU can keep up. My 2 options are to dig into burning a new chip for my current ECU or to completely upgrade the engine electronics to something I can tune on the fly. I think I am leaning towards upgrading the whole ECU to something like a Terminator X from Holley. I'm sure I could get the stock ECU to work with a new chip and some tuning, but at the end of the day I will still have an ECU with 30+ year old technology. Yes I will need to re-wire the whole engine bay again with the Holley system, but I think it will be worth it to have a modern ECU I can tune with a laptop.

Back to my intake... if I decide to go with the Holley Terminator X system I think I am also going to swap out my Super Ram intake for a Holley Stealth Ram. Couple of reasons for this, but the main ones are the simplicity of the Stealth Ram over the Super Ram and the other is budget. With the value of Super Rams right now, I am hoping to be able to sell and then pick up a second hand Stealth Ram and a new Terminator X ECU and be about even. That seems like a good trade to me! I think it will also be easier to troubleshoot any tuning issues I have with Holley if I am using both their ECU and their intake.

If anyone has any inputs I'm all ears before I pull the trigger soon!

[WSSix]

If your ECU isn't tuned now for the engine, you should start there before ripping it all out. Sure, it's old but that doesn't mean it doesn't work just fine. There's no inherent reason it wouldn't provide great performance for your combination.

You need to verify your combination will work the way you want. Do not chase a peak power number. No amount of changing ECU's will change the way a combination works. You should do this before you change intakes as well to ensure you're moving in the correct direction.

I'm not a fan of the old school TPI intakes including the Super Ram. They are not bad but there is definitely better and easier to deal with options. I think the dealing with it part is what would make me swap it out. Don't limit yourself to the Stealth Ram. Look at your combination and decide what you want out of the car and build towards that. You may need to go with a "simple" dual plane intake to achieve your performance goals. You may find you have the wrong cam.

Good luck.

[PTAddict]

I wouldn't be so fast to ditch the Super Ram. All intakes are compromises of some kind. The Super Ram is quite good at what it was designed to do, which was to move the torque curve higher in the RPM range than the standard TPI, but still in the more usable range. It was John Lingefelter's favorite intake back when he was making packages for the EFI small blocks, because it had a major advantage in torque in the 3000-5000 RPM range compared to the LT1 intake of the day (which made a little more power at peak).

Unfortunately nobody makes a comparable intake in the aftermarket these days. The Stealth Ram is a shorter runner intake, with a power curve more like a 4 barrel single plane. For autocross and road course work, the extra mid range torque is the better tradeoff, IMO. To say nothing of street driving.

I would not run a dual plane in a port injected application. Dual planes have more runner to runner variation through the RPM range, which translates directly to cylinder/cylinder air/fuel variation in a PFI application (it's not really a problem with a carb since the air and fuel are already mixed). It's hard to get optimal injector angle in those runners as well.

If it were my car, I wouldn't give a moment's thought to keeping the stock ECU. You can get it to work, although it usually takes a couple iterations of burning chips, logging on a chassis dyno with wideband, then re-burning to get something close to optimal. These days, a wide band closed loop system like the Holley is so much better in so many ways - if you can swing the price, it's the way to go. Either way, I wouldn't run it too much more on a stock tune, there are likely massive lean spots in the fuel curve.

[garage_engineer]

Originally Posted by WSSix

If your ECU isn't tuned now for the engine, you should start there before ripping it all out. Sure, it's old but that doesn't mean it doesn't work just fine. There's no inherent reason it wouldn't provide great performance for your combination.

You need to verify your combination will work the way you want. Do not chase a peak power number. No amount of changing ECU's will change the way a combination works. You should do this before you change intakes as well to ensure you're moving in the correct direction.

I'm not a fan of the old school TPI intakes including the Super Ram. They are not bad but there is definitely better and easier to deal with options. I think the dealing with it part is what would make me swap it out. Don't limit yourself to the Stealth Ram. Look at your combination and decide what you want out of the car and build towards that. You may need to go with a "simple" dual plane intake to achieve your performance goals. You may find you have the wrong cam.

Good luck.

Thanks for the input. Chasing peak power numbers is certainly not what I am after and I hope my post didn't come across that way. What is important to me is driveability, and having the car be reliable and easy to drive. That means starting easily, running cool and able to tell me if something is wrong. I want to trust that my fans are coming on (and going off) when they should, my oil pressure and temps are good and all of that. If I give up a few peak HP to accomplish that then that's an OK trade off for me.

Regarding the intakes, I agree there are a lot of options. See below for why I am leaning towards the Stealth Ram (easy to work on, similar power curve to a Super Ram). I also do not know what cam I have... which definitely could be hampering driveability.

Originally Posted by PTAddict

I wouldn't be so fast to ditch the Super Ram. All intakes are compromises of some kind. The Super Ram is quite good at what it was designed to do, which was to move the torque curve higher in the RPM range than the standard TPI, but still in the more usable range. It was John Lingefelter's favorite intake back when he was making packages for the EFI small blocks, because it had a major advantage in torque in the 3000-5000 RPM range compared to the LT1 intake of the day (which made a little more power at peak).

Unfortunately nobody makes a comparable intake in the aftermarket these days. The Stealth Ram is a shorter runner intake, with a power curve more like a 4 barrel single plane. For autocross and road course work, the extra mid range torque is the better tradeoff, IMO. To say nothing of street driving.

I would not run a dual plane in a port injected application. Dual planes have more runner to runner variation through the RPM range, which translates directly to cylinder/cylinder air/fuel variation in a PFI application (it's not really a problem with a carb since the air and fuel are already mixed). It's hard to get optimal injector angle in those runners as well.

If it were my car, I wouldn't give a moment's thought to keeping the stock ECU. You can get it to work, although it usually takes a couple iterations of burning chips, logging on a chassis dyno with wideband, then re-burning to get something close to optimal. These days, a wide band closed loop system like the Holley is so much better in so many ways - if you can swing the price, it's the way to go. Either way, I wouldn't run it too much more on a stock tune, there are likely massive lean spots in the fuel curve.

Great input and thanks for the comments. I agree the Super Ram has a great power curve... I've read John Lingenfelter's book on making power with small blocks and he definitely raves about it. I recently watched a YouTube video comparing a bunch of small block TPI intakes and below are a couple of screen grabs.

For full credit, the youtube video is by Richer Holdener and the link is here: https://www.youtube.com/watch?v=B3Je1MLTphs&t=731s

The baseline is a 383 with a stock TPI intake (the BLUE line).

The first chart is the Super Ram:


And the second chart is the Stealth Ram:


To me, not a HUGE difference between the 2 but definitely a bit of mid-range torque loss in the 3000 - 4500rpm range. The big question is... is that 20-30 lb-ft loss worth it for the aggravation of installing the Super Ram, and am I a good enough driver to tell the difference? (My guess is not right now )

[PTAddict]

Nice find, real data! I didn't even bother to do a search on Holdener, figured that he wouldn't have bothered with some of the more obscure old school stuff like the Super Ram. Should have known better, he's a testing maniac. Pretty soon he'll be testing ported Model T cylinder heads

Yeah, that torque loss isn't too bad, in fact on a road course shifting at 6000 with a T56 the Stealth would actually be better. So I retract my advice above, you know what you're doing. Still wouldn't mess around with that old ECU, though

[SSLance]

Talking with real world experience here...someone that has raced with and street driven a CCC carb setup, then a manual carb setup, and finally a Holley EFI setup all on a similar SBC setup in a similar vehicle as yours...

Once someone with your ability does the install correctly and begins to learn the Holley EFI software, you'll wonder why you didn't make the change years ago. The amount of real time data you can collect and use to fine tune the software is mind blowing and the results from collecting and using said data to make the engine run better are worth the pain of install.

The main question I would be working on is how best to design the fuel delivery system...retro fitting a fuel module to not only feed the beast but to do it without regular pump failures or fuel starvation issues means going a step above most regular installs.

Being able to salvage your old intake to finance the new parts makes it an even easier question to answer at least in my humble opinion. Good luck with your call.