Other Engine Conversions - non V-8 Discussion of non-rotary engines, exc V-8's, in a car originally powered by a Rotary Engine.

Retaining ps and ac on the diy? custom driveshafts?

Old 09-21-10, 02:54 AM
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Retaining ps and ac on the diy? custom driveshafts?

Ac is something i'm not too hashed about NOT having but it's something i'd like to retain. Bending custom lines and getting the fittings seems pretty standard but how would one go about this?




Also, power steering lines. Many ways to do this. Weld fittings on the rack, Have a hydro shop make you lines, make your own ss lines and use an to metric/npt adapters. What did YOU do? What makes welded fittings a more viable option than using adapters?

Driveshafts. You can go through dss and get what you want made. You can ALSO simply extend/cut your oe shaft down and weld whatever yolk you have on your swap to the shaft but it wont be balanced proper. You'd have to send it off or take it somewhere that CAN balance it. Atleast that's my take. Other options available from bottom dollar up?


If you used an off the shelf kit part for this, dont bother posting "heres a link to prefab stuff". This is for the true budget minded diy engineer only.

Got a custom sump? Show that off too!


Yes, i'm mad at my rotary. That's the only time i post in here. I've done homework on many engines i would find to be a good alternative to the rotary if i ever get/got tired of them but this thread WILL help others with their swap. Not just me. We have alot of people who come in here asking if their swap is possible. If you have baller monies, good for you but there's more than one way to skin a cat.

Price, source and explain as well as you can (pictures speak volumes) and lets see where this thread goes. Hopefully somewhere.
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Old 09-23-10, 08:01 PM
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For the rack, I just looped the lines and use it as manual.

These cars weigh nothing, and are easy enough without assist.

Shouldn't be hard to run the PS pump and rubber lines to the nipples on the rack.
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Old 09-24-10, 07:30 AM
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Your Mystery Project

Pretty hard to give advice when I don't know what kind of car you are working on or what engine you are installing. But I have a few handy hints that might be useful to you or to others.

A good, well equipped AC shop should be able to fabricate any lines you need. I got lucky putting the rotary into a Porsche recently. We used the Mazda AC compressor because we had several spare compressors and the brackets for it. The pressure line to the condenser just hooked up directly, about the right length, just got lucky. The low pressure side, the line coming from the evaporator, through the firewall and into the suction side of the compressor has relatively low pressure. We just cut the sleeve off the fitting and installed it with TWO hose clamps. I don't expect any leakage problem with that, but if a shop charges your system they would likely have the sleeve and a swaging tool, might be able to swage it on the car.

Do not weld any AC or oil pressure fittings unless you have a really expert welder. I do have an expert welder who helps me with my projects. He did weld up an adapter for my oil pressure sensor, and he welds cooling system fittings all the time. He also fabricates and welds oil pans, suspension and steering parts, even welded the steering rod connections to my steering rack on one project. He will NOT weld power steering hydraulic fittings.

We made a custom steel bracket and mounted the Porsche clutch slave cylinder to the Mazda transmission, works perfectly, the line just had to be recontoured to fit.

We mounted the power steering pump on a custom made bracket, shown here, which puts the pump in the same location in the engine compartment as the original Porsche installation. You can see that the short supply line from the reservoir just hooks right up. We rebent all the tubes, which required some patience and no doubt some skill, but we managed it without cracking any of the tubes. I am still amazed we made it all work. One photo shows how the pressure line from the back of the pump goes behind the water pump housing and across the top of the engine. I routes down between the front and rear spark plugs and into the rack - a half inch shorter and it would not have fit.

Last but not least important, we are using the high pressure Porsche fuel pump (for fuel injection) and running it into an RX-4 carb at about 4 psi. The Holley regulator we used can actually handle the 40-50 psi pump output, but we thought it would be more stable with a less radical pressure drop. We used one of the Mazda carb banjo fittings with the return line to the fuel tank, but we thought the stock orifice would be too large. I soldered up the return tube and drilled it out, starting with a 1/16 inch drill. We then deadheaded this into a pressure gage and got 12 psi. So we just mounted this banjo to the bottom of the regulator and adjusted the output to 4 psi for the carb.

For anyone here who does not understand this, we are taking a 40-50 psi pump output and bleeding part of it back to the tank. The more you flow back to the tank, the less pressure you have going to the carb, regulator or whatever. By starting with a small orifice and drilling it out larger and larger, you can flow more fuel back to the tank until you get the pressure you want. In theory you could bleed enough fuel back to return until you get the 4 or 5 psi for you carb without using a regulator, but I don't recommend this. Better to have 10-15 pounds into a regulator and you have a more stable pressure, not dependent on the voltage going to the pump, for example. I did this years ago when I built a rotary GLC, and I used one of those cheap chrome plated regulators, worked perfectly for over 100,000 miles.

More details and photos of the Porsche installation are shown on page 7 of my Cardomain site. If you peruse my various projects you will see several custom made oil pans.

The custom airbox fabrication is shown here:
https://www.rx7club.com/nw-rx-7-forum-33/custom-airbox-fabrication-921044/
Attached Thumbnails Retaining ps and ac on the diy? custom driveshafts?-ac-hoses.jpg   Retaining ps and ac on the diy? custom driveshafts?-clutch-slave-bracket.jpg   Retaining ps and ac on the diy? custom driveshafts?-power-steer-pump.jpg   Retaining ps and ac on the diy? custom driveshafts?-powersteer-press-line.jpg   Retaining ps and ac on the diy? custom driveshafts?-fuel-reg-return.jpg  

Retaining ps and ac on the diy? custom driveshafts?-custom-air-box.jpg  
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Old 09-24-10, 03:07 PM
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Very nice contribution!


And for the record, what i'm considering doing doesn't matter until the engine is on a pallet on my property. I've got a general idea what to do and what needs to be done so really, i dont feel the need to spill the beans or jinx my plans by posting them here until it's underway. Nothing personal.
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Old 09-28-10, 03:08 PM
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Sounds like you should change your screen name unless you are putting a turbine engine in your car

If you stay N/A just about any swap can retain a/c. A turbo setup with proper configuration can retain p/s too. You just need to find a quality hose shop that can adapt them.

Your post is soooooo vague with what engine you plan to use it is pretty useless giving any info to help you.
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Old 09-30-10, 02:57 AM
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I probably should have put a question mark after the exclamation point in my screen name. I'm not anti piston, that's for sure.

Trust it doesn't matter. The two engines i'm considering aren't terribly hard to do and one has been done several times over and has an off the shelf kit available. The other engine is similar but with the intake/exhausts reversed, less output, less displacement but cheaper initial cost.

Things like driveshafts, shifter extentions, motor mount brackets...stuff that can be skinned multiple ways. I'd like to see that stuff in this thread. Img coded pics and whatnot. I wont hold my breath though. Threads like this go to crap rather fast due to assumptions.
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Old 09-30-10, 01:29 PM
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So what are the possible motor choices? I hate guessing games.
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Old 10-08-10, 04:37 AM
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rb20det
rb25det
1jzgte

And i dont know **** about inline six bimmer motors but they seem like another viable option. I'll be reading up on them as i continue saving money for this little project as i feel the rotary and it's affixed parts are really going to but a damper on this project. I want my car to be something i can do trackdays with, drive to work daily, go pick up groceries and take long trips all over the country with. Not some thrown together **** or a gas eating rotary pig that burns through a 1/4 tank of gas shifting at 3k and cruising at 2k in less than 30-40 miles. Really.

I just want some straight six power. As long as it's not a toyota m series or g series engine or an older nissan L series or some bs like that, i'm game for it. Something there's parts for and websites that sell affordable parts with rush shipping if i need it, ya know?


Inline six....pretty much but as cheap as freaking possible, meaning all diy work with very little if any outsourcing.


I've got power steering covered by going without a pulley. MR2 or MRS electric pump. Rear sump is cheaper and easier especially if the pan is steel with a steel pickup so i'm looking into that. I can weld steel. I dont WANT to outsource aluminum welding because i have this whole "pride" thing going on where i like doing my own **** if doing it myself is possible. For instance, i can make my own mounts. That's not a problem. Anything that needs cutting and welding that is steel, i can do. I'm very handy with a mig and tig.

Balancing and machine work is another story.

The driveshaft bit when doing these swaps is the biggest thing for me, even if you're using frankenshafts (combining oem parts to make your hybrid car work) they can be big money and not something you can do yourself and toss on but where there is a will, there's a way and i'm looking for answers. One question in particular:

Has anyone welded up their own drive shaft and THEN taken it somewhere for balancing? How did that turn out? What about you crazy folk that didn't have it balanced at all? Did it grenade on you or did you put countless miles on it without issue?
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Old 10-11-10, 06:33 PM
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Looks like rb20 it is. They're cheap and o-plenty.

Silvertop, not the shitty weaksauce redtop.

1/4" plate steel should be strong enough for mounts.

I'll be using aftermarket rx7 engine and trans mounts and building the rb mounts on top of those.

Thread pitch on rack for ps lines on an fc are? SS -an lines should work. My machine shop ALSO said they wont weld fittings on my rack. Ho hum. The plus side is welding ac lines aint no thing.

Bah, i'll come back to this thread when i get my motor. I got a hit on one and if nobody gets it by the end of the month, it's mine, otherwise i'll continue to sit on my cash and buy one from an importer. We finally have one in charlotte now.

So about that driveshaft, i'll have to take measurements use a z32 front slip yolk and TII rear bolt yolk and have whoever use a dom tubing steel shaft to couple em. Should only cost about $300-350. I'm bummed b/c i did want to make it myself but they spin so fast and are under shearing forces. Better safe than sorry.
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