vw diesel into a mazda rx7

BEN721364

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lews930 said:
First time poster long time diesel lover. I am in the planning stages of trying to install a vw diesel into my 88 Mazda rx7 convertible. The rotary which I love is not known for it's fuel economy (18-19mpg). I love the car and commute with it 55 miles one way to work. Thought I would give the vw diesel a look after hearing stories of 40-50 mpg in the jetta. <snip>
.
Such a conversion would seriously compromise the RX-7's handling, I would think. I suspect that the VW engine is considerably heavier and taller.
 

Rub87

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rez311 said:
Hey! You done yet? Still waiting to see this thing run! :)

1 FD
2 FCs, one with a 20B. FC 4 life! :p
How do you get 400hp from (stock) twins? or do you have something like the BNR kit or..?

Considering a gt35r single turbo on the fd, also have an fc convertible with a knightsports big compressor hybrid and some 20b's
 

12MPGHWY

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Stock twins will do just over 400 WHP (dynojet) on stock ports at about 17-18 PSI, on race gas or other exotic fuel with very short expected turbo life, tuned to the bleeding edge.

An "all bolt ons" FD with stock twins and street legal slicks did a 10.9 1/4 mile.

I have a 13B-re/rew FC with stock twins, run sequential of a haltech

Rub87 said:
How do you get 400hp from (stock) twins? or do you have something like the BNR kit or..?

Considering a gt35r single turbo on the fd, also have an fc convertible with a knightsports big compressor hybrid and some 20b's
BEN721364 said:
Such a conversion would seriously compromise the RX-7's handling, I would think. I suspect that the VW engine is considerably heavier and taller.
Its both not that much heavier, and will have no measured effect on handling.

Hell even an iron block V8 some of which might be 300 pounds heavier, have very little effect on handling.
 
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lews930

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NO it is not finished. Completed that is. I almost threw in the towel a few months back. My Ford cummins swap had me going in circles but I finally prevailed. Runs great and being a 12 valve motor I have NO electronics to give me fits. Except for the starter that went out today. Had it fixed within an hour though.

Started tearing the Mazda down to install the VW last Friday night. I got the radiator and shroud out and diconnected some of the wiring. I figure that if this VW thing doesnt work I'll be ok because the rotary is using 2-3 qts of oil per 3000 miles! not good.

While building the motor mounts I discovered that I hadnt rotated the motor over far enough to clear the hood so a hole will have to be cut to clear the injector pump. I've got a junk steel hood so cutting a hole wont bother me. Once she's in and running I'll do some driving and see if I'm an idiot like some people think. If it turns out all right I'll have the machine shop make a new adapter plate with the correct angle to clear` the hood.

I'll update my album when the rotary is out.

thanks all
 

Logdog

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None at this time, but I'm putting a TDI and Toyota 5 speed into my 122 Volvo Wagon.
lews930, don't sweat it! Anyone that reads these posts is borderline pshychotic anyway. Who cares what others think. Life is the journey and not the destination. Just look at what you're going to learn here. My dad thought that all of my interest in drag racing was a waste, but what I taught myself in the process has been invaluable and I've got great memories to share with my own son. Don't give up. It's just getting good!
 

rez311

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Damn. Some haters in this thread. I'm using methanol injection running 15-17 PSI on a streetport, ceramic seals, PowerFC, etc...

I'm considering the TDI in my 914. Was going to do a rotary, but I'm stuck in the middle. I'd do a 6 cylinder tdi turbo if I had 10K to dump.
 

lews930

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I want to finish it because of a few early comments but I must admit that I'm a little burnt from doing the cummins swap. I think it would be neat and thrifty as well. Given the current condition on the stock rotary I dont think the performance will be that far off.

I think I'll just go with what I have. It it works out I'll do another plate. The machinist told me that building another plate would be cheaper that the first.
 

neljoshua

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CO
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lews930, Interesting idea! I guess this post has been up for awhile, but I am new to the forum.
Gotta hand it to you. I used to have two RX-7's (1982 & 1985)--my favorite cars. This will be neat when you get it done. Do not worry about what others say--it is your car. If they don't sell what you want--make it!
Not sure if this helps any, but I saw a 1st gen (1978-1985) RX-7 on ebay that was converted to diesel a few months back. Very interesting. I'm not sure about the quality of the work, but it was neat!
 

lews930

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Damn. I knew some one would be me to it. Any idea what motor it had? I saw a 2nd gen on Ebay that had a isuzu diesel in it. I'm sure it was a rocket!

I finally pulled the rotary out today. Oil puking out everywhere. Hope to get the oil pan done Wednesday
 

12MPGHWY

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There was also an FC with a twinturbo V8 diesel about 10 years ago, I don't remember what engine it was on an austrailan website.
 

alphaseinor

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rez311 said:
I bet the diesel burns less oil that the rotary. ;) ha ha
x2

Don't worry what other people say here... I'm lurking in the background watching your amazing project!

Have you thought about putting on a turbo 2 hood? wonder if the scoop will clear on that one?
 

lews930

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I thought about the turbo hood but the scoop is offset more to the drivers side. I found a damaged hood and gave thought to having the sccop removed and transplanted over to my aluminum hood. First things first though.

I notice that finding the time to work on it gets more scarce as my kids grow older.
 

gnx7

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I would be curious how this conversion pans out. I'm new to diesels and now own (2) TDI Jettas. If you have the time this conversion would be cool for sure.... strictly for the gas mileage of course.

I'm in the beginning phases of doing an auto to 5speed conversion on an '02 VW Jetta TDI wagon. Collecting parts.... have the car already. Auto trans took a dump within first 300 miles of ownership!

I favour LSx conversions on RX-7's. Latest project is a widebody FD with dry sump LS7/T56/Cobra rear diff to go road racing. 2800lbs/575rwhp low 10's@140mph n/a on 91 octane should be achieveable. In the home stretch with the project... just need to find the time to complete it.
 

lews930

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Time is the part I dont have much of. I have made some progress but it could be years before it's finished. I have the oil pump pick up and the oil pan modified. I will post some pics in my album when time permits.

Complicating things further is my NEW 96 Passat tdi. I found this jewel about 5 miles from my house by accident. $1,700 and she was all mine. Has the typical 96 passat problems but has ice cold a/c so most of the stuff doesnt bother me:) 47 mpg sure does save $$
 

Rub87

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nice, it already has a single mass flywheel so it asked for a nice vnt turbo etc, you know it :D
 

lews930

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Not sure how to approach this. Should I use the windage tray/baffle that came in the oil pan? With the motor tilted over I would think that getting the oil to the bottom of the pan as quickly as possible would be best but I dont know with this VW. I suppose I could cut some holes in the tray on the uphill side to speed oil return

any thoughts?
 

lews930

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I just uploaded some photos of the oil pan and pick up tube to my album in the pic section. Feel free to check em out
 

lews930

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It;s been a while but here's the latest.

After all this time and work to do this swap, the motor sucked a shop towel down the intake:(

You know, one of those blue paper type roll towels.

I had worked all day on it and the day before getting water hoses hooked up and wires ran and is comes down to this. Boy do I feel stupid

I couldnt get it to start and had put the shop towel in the intake horn to keep bad things out. I was calling it a day. Then I thought, let me crack the injector lines one more time. I did and then tried to start it and start it did. I came out of the car to check things over and looked and noticed the other shop towels in the trbo inlet and outlet

I know, you're thinking, why didnt you have it hooked up. I was saving the intercooler for last figuring it was lowest on the priority list for a running car. I should have made it further up the list I guess

Any ideas as to what a ingested shop towel does to a motor other than bending valves and stuff?

I'll pull the intake in a few days to see where it went but I'm guessing it's in one of the cylinders

so how was your day?
 

Rub87

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isit cloth or paper? if it's paper it doesn't hurt, my previous engine consumed a whole part of such blue paper towel, it came out of the exhaust nicely shopped by the turbine wheel.. when it was idling you could hear now and then some cilinder had no compression, but it survived and kicked ass again afterwards ;)
 

lews930

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it was a paper towel and yes it sounds like it has a miss or two. I didnt see it come out of the down pipe as I havent been to the exhaust shop yet,I'm thinking it's still in the cylinder. I'll pull the intake and exhaust tomorrow

lewis
 
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BEN721364

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I haven't followed this thread extensively but am curious as to what the TDi powertrain [weight wise] will do to the RX7's great handling?
 

Ski in NC

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Lewis- Most of it should still be stuck in the intake port. Get the intake manifold off and most should still be there. Probably no need to take exhaust manifold off. Whatever bits got into the cylinder will burn up/chew up/spit out likely with no harm done.
 

lews930

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I looked into the intake and saw no paper. I'll pull it(intake) tomorrow and look in the ports. hopefully didnt bend a valve but with my luck

The diesel only weighs a touch more than the rotary so I dont expect any difference. They put V8 motors in and supposedly have no problems but I've never driven one so couldnt say for sure

Any way, the swap is almost done. a few wires to supply power to a trip to the muffler shop to connect the down pipe with the mazda exhaust and it's drive time.
 

lews930

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SKI in NC, you were right. the whole towel was in a ball up against the valve. i'll post a pic to my album for the curious. it runs well and I'm finishing up soem small details. should be youtube ready in a few days

anybody have a schematic of the alternator? I'm curious if I can just wire the hot from the mazda harness directly to the hot pole on the alternator.

anyone know what those 2 little black wires coming off the alternator do?

thanks
 

Rub87

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one is for the light and one is for rpm output, I think it was called W terminal or so.. you should connect the one for the light to the mazda one for the light and the other fatter mazda wire is just coming from the ign switch as a feedback signal, so you don't need that one anymore..
 

myke_w

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lews930 said:
SKI in NC, you were right. the whole towel was in a ball up against the valve. i'll post a pic to my album for the curious. it runs well and I'm finishing up soem small details. should be youtube ready in a few days

anybody have a schematic of the alternator? I'm curious if I can just wire the hot from the mazda harness directly to the hot pole on the alternator.

anyone know what those 2 little black wires coming off the alternator do?

thanks

Glad to heard you didn't wad the motor Lewis :)

Link us to your pic section if youy wouldnt mind?
 
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