JUN S14

Few quick questions. Is the Petit 20B subframe a direct swap? Does the stock subframe have to be cut out or is it bolted into place? How about the petit subframe... bolted or welded into place? Thanks.

JUN S14

Anyone??? BTW for a FD chasis.

Silex

I take it you wanna do a 20B swap? Best of luck to you and have fun! That's all that matters.

black99

I am positive that it is a bolt in unit(because Pettit said so) it comes along with spindles and I think to get the stock one out, you simply unbolt it also.



Here are two emails I sent to Pettit and my answers... Hope they help, I was thinking of doing this conversion before too, but I kinda deemed it to expensive, although now you got me thinking of it again.




Q.Will you guys sell me one of your custom subframes you use for a three rotor
conversion seperate??? Thanks,
Kevin

A. from Pettit. We do sell the subframes and spindles seperate. The cost is $2,199 exchange



And in another email I asked them about moving any components to fit the 3 rotor in there and they said....

"No you do not have to move the tranny or change anything else. Just bolt the
subframe in. The only thing you have to modify is the steering rack in order
for the oil pan not to hit it. Very easy to do though. "

Hope this helps.

technonovice

Am I missing something? Why do I always hear that it cost $20,000 for this conversion?

black99

Because most people over here have shops do the work for them instead of tackling the job themselves for one. Bermuda20b actually had I KDRotary do his 20b conversion which I hear turned out very nice, he thought it was going to cost I think around 25k but he ended up going over that I think. Another reason is there is alot of other stuff you need besides just a subframe, the motor, which sometimes you can find for around 3k if you are lucky, and then most people have the motors rebuilt, then you need an ecu, intercooler, fuel system, radiator, etc, etc. And a single turbo or have the stock turbos set up to run paralell. Personally I think for a budget minded person not skipping anything they could get it done for 10-15k but that's just my opinion.

rxman720b

Yes it costs more than $10-15K. If you are even thinking of spending that much why take short cuts? Rebuild the motor so you only have to put it in once. So now you have spent $6-10K, $2k for an ECU set up, $2200 for the subframe, $600 - custom radiator, $1500-2K for the frt mt IC, relocate the battery, $6-700 - relocate the A/C stuff, $200 modify the throttle cable setup, $2200 custom single turbo manifold, $1500 single big turbo (ie:T-66), $500 wastegate, $600 add/mount 2 oil cooler, $500 turbo plumbing, And don't forget about a month of labor $6-7K to put it all together. That's a minimum of $25K on the lesser side. Oh yeah there is a lot of stuff not listed that jacks the price up more... 3x850 cc secondary injectors, upgraded fuel lines, fuel pressure regulator, upgraded fuel pump, brake upgrade, polishing all of the aluminum under the hood! But telling someone you've done it to your car for less than $43K.....Priceless!!! ($13K less)
BTW that $43K doesn't include a single turbo upgrade!
Trust me I know!
http://www.3rotorrx7.com

silvr94r2

iTrader: (3)

I don't understand why you would have to rebuild the motor.....they come with around 30k miles right? I have never understood these prices that everyone comes up with. Seems a little on the overdone side to me....guess I'll find out. My 20b should be here anyday....I'll find out first hand how much this is going to cost. Good thing I have 2 xtra cars to work with

cafe

Few months ago a guy was selling his second gen with 3 rotors motor. It was done by PFS anyway he wanted 40k for it. I figure it's very costly to swap 3 rotors unless you can do it yourself and save labor cost.

silvr94r2

iTrader: (3)

Well I got my motor for $1500 with everything......subframe $2200 unless I decide to do it myself.......ECU $1000.....$900 FMIC......$400 alum. radiator.......all the misc. piping and other mods done by me $2000= $8000+/- some change. I can't imagine what else would cost so much. Guess now comes the fun part of finding out how to make it all work. I'll let everyone know when this project gets done (at least 4-5mos. cause of the race season). I guess the biggest charge comes from the polishing and chrome plating and the big single turbo upgrade that the 20B has to have to run

black99

Where did you get a 3 rotor with everything for 1500.00?? Or did you have a hook up to get one at that price??

JUN S14

See a lot of those things you list are going to be done anyways regaurdless of which motor is in there.... upgraded radiator, big fuel system, big turbo, big FMIC, polishing/chroming/powdercoating, big brakes, etc. In the end it comes down to those parts that have to be swapped out or altered to fit in the 20B motor... subframe, throttle cable, a/c, etc. I've done several SR20DET motor swaps into 240SX's so I've kinda been there doing grunt work and working out bugs in motor swaps before. Doing a 20B motor would be much different, but in the end it comes to original thinking, smashing fingers with tools, swearing a lot, patience, and some money. This is just an idea that I am throwing around to doing later this year. Thanks for the advise guys.

silvr94r2

iTrader: (3)

Black99: yes we got it from our engine supplier that we get all our Honda and Nissan motors from....so he gives us great deals.

JunS14: Putting the SR20DET motor in is real fun huh? I love those! NOT! There not so bad anymore....it was just the R&D that wasn't fun. Boy is it a rush getting it going though! I'm doing the 20B over the next 4-5mos. as well. Maybe we can compare notes

jimlab

You're going to take someone's word that the motor only has about 30k miles and everything's perfect internally? Most people want the peace of mind that comes with a fresh rebuild, especially with this much money on the line. Most people are adverse to having to pull out a motor they just installed.

The prices are not "overdone". You'll quickly find out once you start trying to track down fasteners and fabricate intake piping and many other custom parts that there's a reason why the conversion is so expensive.

jimlab

BTW, the 20B cradle from Pettit is $2,100 and requires relocating the steering rack. The PFS solution to the problem is to move the engine back, modify the firewall, and relocate the shifter. Neither is perfect.

If you want to at least save some money on the cradle, you should contact Grant Robbins at Granny's Speed Shop (www.grannysspeedshop.com). He's been interested in buliding a 20B derivative of the V8 cradle that we developed, but may have already done something along those lines as far as I know. He may also have solved the steering rack issues, since we discussed those briefly as well. In any event, he won't charge you nearly as much as Pettit will.

silvr94r2

iTrader: (3)

Jimlab: thanks for the advice...I'll take it and give him a call. At least that would save about a month of R&D. As far as the other issues......we have done many many engine swaps. We did one of the first GSR swaps into a 87 CRX back in 95 complete with GSR wiring and dash and everything. It is really slick! I do understand what your saying though and respect your opinion. On the engine deal....doesn't the Japanese have to change their motors at a certain Kilometer (30k or 40k)? That's why I was saying that a rebuild wasn't really a must....a should do but not a must. Even if the motor needed rebuild I don't think it would be another $10-15k. Your doing a motor swap right....how much is yours gonna cost? I hope you don't say $25-30k. I would guess yours to be about the same as what I came up with on the 20B....$8-10k. Don't count all the xtras your adding on like the Hogan SM intake and polishing and chroming. Just the base cost....thanx

silvr94r2

iTrader: (3)

Also to whoever is listening.....am I wrong or did I read quite a few places that it's not hard to make around 500hp with the stock twins on a 20B. The reason that I'm even going to do it is because for the amount of HP and reliability that you get out of a 20B it's cheaper in the end. I've got about $20k in my car and it's not even done....that's also at mostly hooked up pricing and me doing alot myself. My car will have about 550hp when it's done for about $25k. On my girls car I think I'll have less than that ($25k) and as much power (550hp) with more reliability. Plus her car will be a show car....so how can you beat that?

JUN S14

The reason why I like the 20B is that it will have a much better broad power ban, and a lot more torque than a 13B pushing the same RWHP...

jimlab

While the Japanese may follow (as rumored) an emissions program which makes it simpler to pull the old engine and install a new engine at 30k miles than to take the steps to pass emissions, those engines are subject to all the same calamities that engines in our own junk yards face... for ~30k miles, some of the 20B engines I've seen look like they were found at the bottom of swamps.

The rebuild doesn't cost a huge amount of money, but I for one would not be comfortable going through a highly expensive engine swap and taking for granted that the engine internals are fine. If they aren't, you'll spend a lot of time pulling the engine back out, fixing the problem and re-installing it. FAR better to take the time to have it rebuilt properly while it's out of the car, unless you're just trying to cut every corner you can. If you are, all I'm saying is don't complain if your strategy backfires.

You can probably do a 20B swap on your own for $10-15k if you can fabricate the many parts that you'll need which aren't available off the shelf, and you can find good prices on the parts that are. Stand-alone engine management is almost a necessity, unless you're content with stock boost or can track down someone who can *reliably* reprogram a Cosmo ECU. Not that many people have experience with tuning or reprogramming for the 20B in the US, so that's a liability. You'll almost certainly want to eliminate the stock turbos as well, so that means a single turbo setup, or at the very least, having the stock turbos gone through. You'll need a front mount intercooler, which isn't exceptionally cheap, and you'll have a lot of intake and intercooler piping, exhaust, and other parts which need to be fabricated to make the swap complete. Costs can add up very quickly, obviously.

You could probably do the V8 swap (fuel injected late model LT1 350 cid and Borg Warner T56 6-speed) for $5-6k fairly easily, if time were not a huge concern and you can do a lot of the work yourself.

j9fd3s

iTrader: (3)

i just got my 20b and it has 37,000kilometers on it. i got everything with the it, even the air box. the original air filter that is in there has about one inch of crap on it. all of the hoses are baked, the belts are shot, and it smells like fuel. remember the fd's at 30k miles? the 20b's are the same except they have the automatic to heat things even more

mike

jimlab

My "30,000 mile" 20B had a wiring harness that broke in several places during disassembly of the engine accessories. It looked as if several mice had lived in it over the years, and the hoses and solenoids for the turbo control system were what you'd expect to find on a 30,000+ mile heat baked rotary that then sat someplace for an indeterminate period of time. Cracked, brittle, broken.

The apex seals were pitted, although it had good compression indicating a good core for a rebuild. The intake elbow was damaged, two exhaust manifold studs had been broken at some point, and the injectors were of dubious quality. The alternator was shot, and at some point, the engine had been hit hard enough that the water pump flange the alternator bolted to had cracked and broken off. It was an old break, and the engine was shipped properly to me inside an enclosed crate.

Even if I had been able to use the core as-is, I would still have had to spend a considerable amount to replace the wiring harness or fabricate a new one and have the injectors at least cleaned and blueprinted, if not replaced, not to mention all the other problems. I got mine for a relative bargain at $2,900.

And don't forget that you'll probably want to change the front cover to get rid of the distributor shaft, and change the rear plate to bolt up to an OEM 5-speed instead of an automatic bellhousing. One way or another, the motor really does need to come apart before it goes into an RX-7.

Unless you have the chance to inspect your engine before buying, it's basically a crap shoot. Until you have your engine in hand and can assess how much you'll have to replace, don't make any plans on being able to save some coin on the engine by skipping a rebuild.

silvr94r2

iTrader: (3)

I'm gonna take pics of it within the next couple of days....I think it is one of the best looking engines that we've gotten from these guys. It is in perfect condition!

Jimlab: you seem to know alot about this swap....do you have any reference points that I could look at to make my job easier? I've tried doing searches on here and asking questions but it seems that there have been so many 20B posts....noone even bothers to post anymore. I'm gonna use the AEM ecu to get the ball rolling quicker. I have a friend who will help out with that. The rest will be trial and error except for the cradle. I'm gonna give GrannySpeed a call for that puppy.

jimlab

I had to do the same legwork in my own research when I was also considering a 20B swap. Unfortunately, there's not a well documented body of knowledge on the web anywhere that covers this.

silvr94r2

iTrader: (3)

Looks like I'm on my way then....wish me luck I'm gonna try and document my work so that when I'm done maybe someone else can benefit from it. I'm kinda excited now!

Boostn7

Also have a 20B-FD in the works....

I'm also interested in that craddle from Grannyspeed shop and may also give them a call.

Jimlab: why change the rear plate to fit the oem 5 speed ? doesn't it bolt right up...seems like it does.

At the moment I have the engine in the engine bay bolted to a FD tranny with Turbo II bell housing & input shaft which moves engine back another 3/4' inch and offers bigger selection of clutches.

John D