AC for SR20DE swap

[GoldHawg]

I haven't been able to post much on my build thread, but I finally have achieved an important objective for the build--, after MANY hours I have completed the design and prototype for an AC bracket setup. I started with Shannon's design but knew from the beginning I needed a different bracket to tie to the rear of the compressor (I didn't like the look). Last year's efforts had me close (documented on my build thread), but I didn't have the angle quite right for the belt. In the mean time, I have purchased a small CNC Plasma to help build things like this for myself and others in a small business. I was able to get very precise measurements and finally nail the angle for the serpentine belt. But it was still possible to slightly twist the compressor by hand (albeit with a lot of force), so I had to design a bracket for the rear. I had an ugly piece of steel that I made work and that got me there--but too ugly for me or anybody else. So...the solution is here. While this bracket won't get much force at all, it provided the final piece to give an awesomely rigid compressor; I'm pretty happy. I plan to have up to 10 kits available initially for others to purchase if they desire (no pricing yet--sorry).

So what's needed next? I still have to take the prototype main bracket (which requires welding a tube in the middle of it) and make a jig to be able to duplicate perfect copies. The rest is ready to go, since every bracket is CAD designed and CNC Plasma cut. I also want to put the tub back on my car to double check no interference with the steering shaft. But I want to get the custom header done first to check its fit with the tub at the same time. So I'm probably one month away from having kits ready to ship and pricing available. One question for those potentially interested. The main brackets will be from Hot Rolled Pickled and Oiled steel; would anybody that wants a bracket potentially want it sent without coating, or would black powder coating or anodizing be preferred?

[silvertiger]

GoldHawg,

I would be totally interested in one for me SR20DET project

Looks great

[GoldHawg]

GoldHawg,

I would be totally interested in one for me SR20DET project

Looks great

I don't know if if there is room for a DET swap, but I would be very happy to send you the prototype in a few days to verify fitment. PM your # and we can discuss. EDIT: Just looking at some DET pictures online; looks like there is room. But we can still talk about fitment check if you like.

[dynaguy]

I'd be interested in the for my s13sr20de car. Black coating preferred. Pat

[GoldHawg]

I should have made a few other observations.
First, this will work with those that are using Spriso mounting locations. Don't see why it wouldn't work with others, but placement is good for Michael's locations. Second, this is only going to be good for Sanden 7B10 compressors. Finally, the bolt that I tie into on the new bracket is where the oil dipstick normally is tied into. I suspect it can still be used (maybe even just go in between the bracket and the water outlet, but there may need to be some modification on the user's part. Since I'm going to have a custom header, I won't likely be able to use the stock dipstick, so I haven't thought about this for others.

[family_2k]

Looks awesome! I would be in for a set as well.

Will be running an SR20DE S14 with standard FWD exhaust manifold.

Black anodized would be nice, but powered coated is also a great option.

[GoldHawg]

Done with one laborious part of the kits; all the spacers are fabricated. Since the size needed to keep belt alignment is not an "off-the-shelf" item, I had a few hours on the lathe for the spacers after cutting them to exact length on the cold-saw, but both the aluminum ones as well as the steel ones that go in between the compressor arms are now complete. Jig is made, and I hope to nest the design onto the plasma this weekend for the most efficient cut possible.

[Vinnyz]

Is the Sanden 7B10 off of the SR20 cars? I ask due to my compressor sitting in a storage. I would certainly consider this bracket for mine as I had originally written off the idea for time constraints.

[sfdaugherty]

No. The Sanden 7B10 is a very small aftermarket compressor. It is a very tight fit to clear the steering column in our cars.

Shannon

[GoldHawg]

Labor Day weekend meant much labor, I worked a lot of Saturday and almost all day yesterday. I'm well on the way to getting some kits ready for sale. While the CNC Plasma is very accurate on larger holes, smaller bolt holes are not that good, especially if they need to be precise (as in the case of the diameter that the small cross tube goes thru on my inner bracket. And the outer bracket must be drilled after a plasma "peck" center punch so three of the holes can be tapped for a 10mm bolt (I stayed with metric bolts, just because!) which I will supply. So, all the inner brackets are done, and about half the outer brackets, and I'd previously finished the aluminum spacers. When I finish the outers I'll take all the brackets down to my powdercoater for finish in semi-gloss black.

The pic with the complete setup on was with the first fully finished weld and final configuration. I wanted to make sure that any distortion/warping that would happen from the weld (and to a small degree the plasma cut) would not affect anything, and the good news is that everything still is great. The jig I built will tend to hold everything in place while the welds cool (only a bit of the finish welding is done outside the jig). However, when I first put it on, the setup did want to flex a bit! Oh no! But I had forgot to re-tighten the front cross bar. As soon as I did that, it was firm as a rock. The key for this setup is all the brackets working together, and for firmness, both the front tie in bar and the aluminum rear bar are critical for no possibility of flex.

One new wrinkle, I was not happy with the 3-rib belt on the 6-rib compressor. Taking a closer look at Shannon's I see a larger belt. I've found out that at least the earlier S13 DET's had a 4-rib outer pulley on the harmonic balancer. I've bought one from a member of another forum ($40 used) and will swap that on with a 4-rib belt. I'm not sure if the 3-rib belt would ever slip, but the 4-rib has got to be better. If you're going this route, I'd be on the lookout for a used harmonic balancer if you have the 3rib one like my S15.
Edit: Got mine in and the guy had nicely rattle canned some black spray paint on it to cover the rust. In hindsight I should have just bought a new one from FRsport @ $137 given where I am with everything else in this build. If anyone that wants a kit needs one and wants to buy a used S13 harmonic balancer, I'll have the one I just bought available for $40 more!

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[sfdaugherty]

Now that you mention it Jeff, I think I did replace my S15 pulley with my S14 pulley.

Shannon

[GoldHawg]

Brackets back from the powdercoaters and I've got all the parts. A couple of wrinkles for those that want one (beyond price; I'll crank out the #s soon and post it on the classifieds). When I swapped over to the 4 rib S13 serpentine, my eyeball says that some of the tilt upward on it was gone relative to where it was before. Don't know how, but there appears to be some variability in that. I think it will be just fine but I did have the brackets optimized for the previous 3-rib S15 pulley. Also, now that I have the 4-rib pulley on, where the belt rides in the AC serpentine groove makes a difference as to where it will ride on the tensioner. I chose to put the 4 ribs in the center 4 ribs of the 6 rib pulley on the AC. With that, I needed the aluminum spacers I fabricated to go in between the tensioner and the bracket to be a bit thicker. I'm likely to just send thicker ones like I used; you could aways put on a belt sander to take them down somewhat. Alternatively, I could send one a bit narrower, and you could add a washer in between to increase the thickness based on where you wanted it to sit. Anyhow, here is how the finished product looks.

[Bigtaku]

You already know I am in for the first batch! You have done something very special!

[GoldHawg]

One is out for customer install now to verify fitment in another car. Pending that successful conclusion, I'll be ready to set prices and take orders. Hopefully get installed in the next week. If someone wants one that is ready to install and run the engine at rpm, that would be great to know--pm me. My only concern at selling these at this point is that I haven't personally been able to run it, and I'm still at least a year away from having my car done. So if someone could run one up at higher rpm, that would give me more comfort, even w/o engaging the compressor on (which would be the best). In any case, I'll be offering money back guarantee for some decent time period to make this work.

[sfdaugherty]

Jeff asked me to install his AC kit to test the fit. I replaced my "one-off" brackets with his and must say that I'm impressed. This is a high quality kit and the compressor is SOLID! I'm confident that it will handle the 7600rpm redline of my Autech engine.

It is a much more elegant solution than mine especially the rear support (now there's room for a header). For my compressor (a Tuff Stuff "Peanut" style equivalent of the Sanden SD7), the all-important clearance to the steering shaft is about 5mm.

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Fortunately for me, Jeff used the same GM tensioner for the belt that I was using (a Gates 38159) so I didn't have to buy another.

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One word of caution, DO NOT tighten the bolts until you have all of them started. The tolerances are that tight.

If you are considering installing AC in your SR20de roadster, this solves one of the greatest challenges . . . mounting the compressor to the engine.

Now all you have to do is stuff the evaporator under the dash!

Shannon