Rebuilding my first Rotary, Is a Bridgeport too Optimistic?
 

The time has come for our lemons car to get a spare motor.

We have gotten 12A, which was "not running due to compression on rear rotor", which I am assuming is an apex, but who knows what else we could find while in there.

I've watched some videos online, and also read lots of forum posts here... and it seems pretty straight forward. I would like to do a bridgeport.... technically in the lemons rule book, its not actually adding cost to the car- I am just removing material ;) .

As a note, I've done my fair share of 3am piston engine rebuilds due to thrown rods, and spun bearings at races so I'm not a noob to being mechanically inclined.


Any reason I shouldn't consider doing a bridge-port while I am in there?

Theres many reason to, and many reasons not to. Will it actually be for strictly race events? Or do you want to daily it? If the word daily even come across, don't bridge it, its not worth it, if the engine will probably never see below 3K RPMs, than you could to get some more out've it

The term daily really doesn't cross this car. Strictly a race car, full cage and totally gutted and themed for lemons... :)

Since I live in Michigan and the car is plated, I am sure I will end up driving it to work (2 miles) or random Cars and Coffee shows for the pure fun of it - but I daily an e92 and an e30.

Ahhh, another michigander, our #'s grow lol

If its like that, you can bridge it. But, keep in mind 12a parts are getting scarce. So if ya blow it parts will be difficult to find

If you want the most bang for your buck you'd PP it, that really wakes up a n/a motor, and you don't have to mess with ports.

But, its all about budget, especially since its for lemon racing

welcome to the board. :)

if adding to the cost of the car will be an issue, then i have to ask does it already have a decent exhaust system (with a header)? if you know your way around a carburetor, you can do some stuff to the Nikki and get it up to the task. however, you will need exhaust for the bridge to work well.

that's my only input.

Just keep in mind that a Bridgeport will start a whole host of other upgrades. Your stock port headers have runners which are too long. The stock carb is a major choke point.

NA bridgeports make power high up in the RPM range so to get the most out of that power, you'll need to replace the stock flywheel with a lighter unit. And a scatter shield will be required.

The noise will be...significant.

Thanks for the feedback so far guys,

@diabolical

- The Car came to me with what looks to be an RB header.. Its straight-piped with a "muffler" on the end, but its quite free-flowing.

As for the carburetor, its a stock Nikki with a busted accelerator pump on it (which will be repaired). From what I have read about hogging and soldering venturis on the Nikki, I would rather find some way to move to a carb that has support.

We have been checking for deals on the forum for an RB/Holly setup but the cost isn't too nice..

I will post photo's of the progress. We recently received two used 12A's from a good friend for a total of 100 bucks! We plan to take apart and make 1 bridgeported engine from..

@ Aaron Cake,

The term "scatter shield" makes me feel sketchy, but thanks for the reminder. I suppose I value my ankles enough that we should consider it a worthwhile investment.

Is there a requirement to upgrade the fuel pump / FPR in the case of bridgeporting?

well, i guess that's a start. provided you have the resources (skills, friends with skills) to modify the header and re-do your exhaust system, you can probably get away with a decent exhaust in the end.

with regards to the support out there, you have things VERY backwards! ;) there is far more support for Nikki modifications than there is to even get the Holley to work in the first place. start poking around the Gen I section and you will find a lot of material.

going with a bridge, it is my humble (and somewhat unsolicited) opinion (1) you're jumping in the deep end of the pool, and (2) that a properly sized Holley would be better in the long run, but between the possible (and likely) cost and support issues, you may want to stay clear until you have some with rotaries and what they like and dislike.

first ... what are you actually allowed to buy/spend? it's a little difficult to offer advice if you're not allowed to buy certain things. at any rate, any decent fuel pump (Mallory, Carter, Holley, etc) that can give you good, consistent volume will be more than enough. you will need an FPR to suit the carbie. if you stick with the Nikki, get the 1-4 PSI Holley FPR. if you go Holley, then get the 4-9 PSI Holley FPR. i know it might sound like advertising, but the bigger regulator simply flows too much for a Nikki.

Thanks for the feedback Diabolical.. You have me reading the Nikki-mod posts religiously now, but it will take time until I understand all of it.

For cost, we can attribute "sales" of parts from the car towards purchases of mods. So we are selling interior, HVAC, dash parts and some other misc items towards the engine build.

We can afford to buy a RBHolly or RB down draft if its going to help with tune-ability, hot starts or reliability for the bridgeported engine. Reading some of the posts, I am not sure if its really going to help all that much.

Long story short- If we are bridge-ing this engine, Then we should plan to mod the Nikki, or have some other carb solution to make use of all that work.

well, your biggest advantages of staying with the Nikki are (1) it was designed for the engine and (2) the support you will get with it. as i alluded to earlier, i believe a nice Holley (550???) would probably be better than a Nikki to get you close to maximizing your engine in the long run, but it probably won't be a smooth road to get there.

that said, don't snub your nose at the Nikki either. :) your best on-board resources are probably going to be the following guys: Jeff20B, Wankel=awesome, J9fd3s and Peejay. modding the Nikki will probably be pretty intense, but if you read the volumes of work Jeff has laid out there, it should give you a solid blueprint. if you ever find the same for a Holley, then let me know. ;)

There certainly is more information out there on the Nikki when it comes to the 12A.

I am going to try my hand at all the changes to the Nikki prior to going in deep with running a holley setup. I will keep the thread updated on our progress!