howracer

hello 3 rotorites,



this is my first post to the 20b forum. a friend, Dick Lambert, recently acquired a nicely built 1995 fd 3 rotor and i am in the initial stages of taking a good look at it from an engineering perspective.



my background is 22 seasons of SCCA Nat roadracing, the last 6 in a tube frame mazda rx3. i am a suspension guy, i own a shock dyno and a high tech spring rater as well as a bunch of cool laser based alignment tools... (after having plotted the entire fd geometry i can tell you why the fd drives like a racecar... it is because it has a true racecar suspension complete w negative camber gain etc etc.)



i was concerned, firstly, w how much front weight the 20b added... so onto my scales it went. i was positively impressed.



dick's '95 3 rotor weighed 2694 with no gasoline on board. dick has another 95 fd w an rx6 single turbo w very light wheels, exhaust etc. i weighed it at the same time and it weighed in at 2517 with no gasoline.



the 3 rotor frontweight was 1395 versus the 2 rotor at 1285. both cars unfortunately still retain the stupid power steering and a/c so you could remove at least another 60 pounds of nose weight. (the 3 rotor did benefit from the battery relocated to the right place whereas the 2 rotor had a smaller battery in the stock location.)



considering the major improvement in torque and hp w the 3 rotor i was very impressed w the modest increase in front weight. if it was my car the power steering and a/c would be gone leaving just 1335 (51%) on the front tires.



i drove the car briefly and being in Door County (just north of Green Bay Wis) and dealing w 35 degrees ambient w a poorly tuned temperature-corrected Haltech E11 and not having time to do some tuning... boost cut etc... i was initially impressed w my reading of the handling and front end geometry. the car has either a Pettit subframe or something similar w a relocated steering rack and lengthened steering arms. in the next few weeks i am going to do a bump steer evaluation to see what the real story is re the steering relocation and will report back.



one item that blew me away was the SOUND of the motor while driving. it immediately made me think of a Ferrari 12 cylinder which i consider to be one of the greatest sounds made by man. (along w an unmuffled rotary of course). what a sound.



Dick's car has a T66 on it and we will be shipping it off to my favorite turbo guy, Kevin Draper, at Majestic Turbo to be checked over. everything on the car is new but Kevin is the Dr. either we take his advice and go to something bigger as the T66 makes 68 lbs/min (around 512 rwhp) or he will machine his customary 4 ounces off the turbine wheel and replace the compressor nut w a bullet which will increase the compressor flow by 14-18%.



we will do some tuning and eventually get steve kan to do some real tuning after the snow melts.



i look forward to sharing whatever we learn.



howard coleman

Mazderati

As I understand it, mounting of a 20B can either be done so that more of the engine is moved forward or more of the engine is moved backwards. I would be interested to know how the handling/weight distribution of the Pettit subframe assembly, or the like, would compare with the other method of mounting a 20B engine.



I look forward to seeing your results.

howracer

yes, there are 2 general methods of locating the engine. one envolves moving the steering rack forward and down... along w relocating the steering arms. the other method envolves hacking, er cutting, the firewall and trans tunnel both of which contribute to the torsional rigidity of the body which is necessary to maintain the suspension geometry. moving the engine back is a great idea if you have unlimited resources and know what you are doing. it has one unavoidable result which is it moves the shifter back. yikes. i would rather just remove the 100 pounds off the front by taking off the power steering, a/c, flip up headlights etc.

howard coleman

j9fd3s

thats cool stuff. my 88 t2 with 20b weighs, 2860lbs, i removed the ac and ps, but everything else is there. i even have the stock (heavy!) turbos.



if you want some help with the e11, lemme know i'm running one too.



how does the t66 drive? i'm considering going single and i want to keep the stock 3000-6500rpm power band.



oh yeah, and the noise is sweet

ccarlisi

From what I understand the shifter problem can be solved by using a different trans case, from a rotary pickup I believe. This does nothing for the resource problem mind you



Autotech claims their conversion moves the motor 6-7in back and 3-4in lower. I believe this is relative to the stock motor but the site isn't clear on that. They also provide a picture of the shifter location. It looks very reasonable.

j9fd3s

ive seen the autotech cars and the motors are very low, and further back. the only rear tranny housing that will work is like a 87+ b2600 one the shifter is further forward, but it does not have a power plant frame so you'd have to fab a mount