V8 RX 7?

[andytk]

I know it can and has been done.

Common in the states cos there are plenty donor engines and plenty abused rex's.

My question is, are they common here?

On paper it sounds like a good thing.

V8 power + torque, with lightweight chassis and excellent handling.

Apparently there isn't much difference in weight either, a chevy V8 Rx 7 (no aircon) weighing within a few Kg of a rotary car (with aircon).

Just an outside bet on my soon to be list of cars to consider.

The only thing that really puts me off a standard Rx 7 is the attrocious fuel consumption. That and the age/milage of the engines on the rex's in the price bracket I'm looking at.

Anyone know anything or have any good links?

Andy

[flat_steve]

Here you go:

www.mazdarotaryclub.com/forums/search.php?s=&action=showresults&searchid=240625&sortby=lastpost&sortorder=descending

[shadowninja]

I like the idea!

[iaint]

Disgusting!!!



I know it's been done a few times with the FC but not seen any details of an FD conversion.

While the overall weight might be close (and no way would I lose the air con from my FD!) I suspect the balance would be messed with. The bulk of the FD's engine weight is behind the front axle and low down and the V8 conversion would overhang the axle and be higher.

[robdickinson]

As said been done but I dont see the point.

Weight disrtibution will be all wrong, one of the big benifits of rotary is the small unit and its placement.

As to common or not here, neither V8's (chevvy) nor RX7's are common, so I doubt theres many.

[Neil_H]

I agree it would totally screw the cars handling up. Leave it to the Yanks who don't understand such things.

[dinkus]

If you've got a big wadge of cash to throw at it then you could easily get an RST-V8 in there

[Pierscoe1]

along these lines.. there's a brief mention in J-Tuner about an FD with an SR20DET engine..

as said above, the appalling fuel consumption, and engine life worries are the only thing stopping me buying an FD.. so one of these conversions would be great!

what about the 2.5l scooby engine? do you think you could get that far back enough in the chassis?

[iaint]

Pierscoe1 said:

along these lines.. there's a brief mention in J-Tuner about an FD with an SR20DET engine.. as said above, the appalling fuel consumption, and engine life worries are the only thing stopping me buying an FD.. so one of these conversions would be great! what about the 2.5l scooby engine? do you think you could get that far back enough in the chassis?

I'd doubt it - the 13b is reall very tiny, it's the ancillaries (like waterpump, alternator, airpump and turbo pack) that make a huge difference.

When you look into the FD's engine bay you can see the top of the inlet manifold, the top of the engine is about 10" below this (theres' a big gap under there filled with turbo controll 'stuff').

Getting a scoob engine to sit low enough would be tricky I think and also - isn't the scoob engine transverse? that'd be a complicated bit to fit in there.

RX-7's aren't unreliable when you take into account the performance and age of most of them - mine's a '92. Even if you bought a dog (engine-wise) you could have it rebuilt 3 times for what you're looking at to do a good conversion. Even if you rag it and don't look after well it you're talking minimum 20k from an engine. Realistically 60k per engine is reasonable so about 4 years of motoring.

I've just done 12k on my rebuilt engine - 3 oil/filter changes and about 5 litres of oil on top of that. Maybe £120 in total as I use 'expensive' oil. Not used a drop of coolant and nothing else to note.

In that time though I have dropped about 3k into upgrades

[robdickinson]

Also how does the crank/clutch line up with a piston engine?

Rotary its in the center, meaning driveshaft is 6-8" higher than a similaly heighted piston engine?

But the rotary realy is small, think 3 average boxes of cornflakes or so.

[Pierscoe1]

for me, it's less about the engine worries, and more about the REALLY bad mpg...

I just think I'd dread using it.. let alone, for example, driving down to the south of france for our holiday... the fuel bills would end up more than the accomodation and channel crossing put together!!?!?!?

just chucking ideas about obviously.. as I'm not in a position to do any of it just yet!

edited to ad: anybody know who did that RB20DET>RX7 swap in J-Tuner?? it's page 58, bottom left, gold car with gullwing doors(boo)..

>> Edited by Pierscoe1 on Tuesday 17th May 13:27

[iaint]

Pierscoe1 said:

for me, it's less about the engine worries, and more about the REALLY bad mpg...

Going fast burns fuel

~17mpg pressing on
~22mpg motorway cruising
~7mpg blatting round silverstone

If you're actually that bothered about the mpg get a Prius.

[Pierscoe1]

easy to say when you can afford it...

try comparing it's mpg to other performance cars....

the nearest bad mpg I found in Evo was a maserati 3200GT !!!! and that's a BIG car with a tuned V8.. and it still had better mpg than the FD!

[andytk]

Hate to break it to you guys but I've read about the conversion on the web.

The V8 does indeed fit in BEHIND the front axle so it doesn't truely mess with the weight distribution. Although a rotary is quite small its associated pipework isn't.

Also from what I hear the FD conversions regularly beat normal FD's at track days and the like so handling isn't wrecked.

Just wondering if there were any in the UK.

Andy

[Pulsatingstar]

Yeah there are are.

Cant say im a big fan of the idea though.

[DanBoy]

The FD is a beautiful car, but surely the very essence of what makes it so good is its engine!

[Robdickinson]

Also rotaries are thirsty, but when flat out there probably less thirsty than piston engines, it sjust when not at WOT are thel less efficient.

bizzare, the 787b actualy won lemans 24hr partialy because it was more fuel efficient.

[Pierscoe1]

it is weird.. now you mention it, I remember that thing about the 787b..

are rotaries actually as/more efficient than say a 2l turbo boinger giving out the same power at full chat on a track for example?? anything to substantiate this? would certainly be interesting to find out!

also, please provide links/pics/details of the V8 conversion... would LOVE to have a look at that! :yesyes:

as for the argument about it spoiling "what is the rx7", yes, you could say that the rotary is a core part of the cars character.. but at the same time, I think it is also it's achilles heel... ignoring possible weight-distribution probs for a moment, I for one know that I would buy an FD tomorrow, scratch that, I'd buy one right now, if I knew I could depend on it's engine as you could a 4-pot, and not spend £500/week on fuel.... there are without doubt many others that feel the same..

not bashing the rotary, it is great at what it does, but there's no doubt that it's hampering an FD's ability to be used every day.. when the rest of the car would surely make simply the ultimate coupe this side of an NSX !?!??

just my 2c obviously...

and I'll probably buy one anyway despite all that, just because the shape is so

[Pierscoe1]

Really!?!? <10mpg on a blast?

blimey.. that is interesting..

anbody have any mpg figures for RB20DET or Mitsu Evo engines putting out 250-300bhp??

maybe I am expecting too much, but I thought a 300bhp S15 would be much more economical than an FD.... wrong?

[Pierscoe1]

and the V8......



you can even buy all the bits from this place, subframe etc, for the chevvy V8 conversion.. looks pretty tidy!!

also.. anybody know what motor this is?:


ediyed to ad:

Found it!! RB20DET in an FD.. now that sounds appealing.. can't find any figures for weight or weight-balalnce change though.. and the gullwings are bound to screw that up anyway!!



>> Edited by Pierscoe1 on Tuesday 17th May 21:35