V8RX7com

After installing the V8 in my 91 convertible RX-7 I have wondered how much weight that I have actually added to my car. A stock rotary powered RX-7 convertible weighs about 300 pounds heavier then a hard top version due to added structural bracing and weighs 3,140 pounds. I had my car weighed today at a local performance shop and here was my results:

No driver, quater tank of gas, convertible top was down
Left Front = 943 lbs. Right Front = 739 lbs. Front total = 1,682 lbs.
Left Rear = 708 lbs. Right Rear = 873 lbs. Rear total = 1,581 lbs.
Total weight 3,263 lbs. Front 51.6% Rear 48.4%

Driver inside car, quater tank of gas, convertible top was down
Left Front = 1,008 lbs. Right Front = 760 lbs. Front total = 1,768 lbs.
Left Rear = 807 lbs. Right Rear = 908 lbs. Rear total = 1,715 lbs.
Total weight 3,483 lbs. Front 50.8% Rear 49.2%

To sum things up, I've only added 123 lbs. of weight with the V8 conversion and with me driving the car with a full tank of gas, the car would almost be exactly 50/50. Now that the car been weighed, these are facts, not my opinion. Keep in mind that my car is a convertible (heavier) and during the conversion I did a lot of things to help balance the car (moved the battery to the trunk, used aluminum heads, etc.) Needless to say I was both happy and surprised with the computer scale results and this should take away the argument that the V8 conversion destroys the 50/50 weight distribution of a stock RX-7, at least with the convertible RX-7 anyway.

Felix Wankel

Nice TPI setup.

TonyTurboII

Hm, thats a pretty good job. That is what a V8 Rx7 should look like.

tmak26b

No RX-7 should have a V8

BlackSport0187

I think you doctored up those results a little, come on you can admit it.

Can someone tell me how adding more weight to the front of a car doesn't affect the handling and weight distribution?

Anyway, the bottom line is V8 RX-7s are stupid. I don't care if they are faster, more reliable, ect. RX-7s are a work of art, and a great technological achievment. Adding good old "detroit muscle" destroys them, there should be laws against such things.

Nice paint job though,
Ike

Evil Aviator

I suppose that you missed the fact that he relocated the battery, used aluminum heads, etc.

I also have a lot of people asking me about the weight distribution on my 20B conversion. It's interesting how nobody ever thinks about the added front weight of an FMIC, larger radiator, big turbo, etc. It's all in how you build the car, people. Besides, you don't see too many Porsche drivers complaining about their weight distribution when they are interviewed after winning a race.

Snrub

iTrader: (1)

Just curious, do you have any real-world performance numbers for your car? eg. 1/4 or 0-60.

V8RX7com

I figured someone might accuse me of doctoring the results so here is a scan of the actual print out. I'm not saying any of you should rip out your Rotary and install a V8. I was just showing that you can install a V8 in a RX-7 without destroying it's 50/50

Felix Wankel

When are you people going to learn ITS NOT YOUR GOD DAMN CAR??

He can do what he wants with it.

How come people drool over a 20B swap, but **** on a V-8 swap?

tesla042

What's the stock right/left distribution? 250 lbs toward FL seems a bit high... Of course, 100 is countered by the RR..

-Tesla

Redwood

I think that your car looks damn damn good. While I love the rotary and wouldn't change it for the world, a V8 swap is still cool and unique. And if the outcome is a car that looks that good, that straight, and that tough, it's a good choice.

Great work. If every V8 swap was done so clean and the balance was maintained, perhaps the hostility toward them would decrease. As it stands, you'll have to put up with a lot of ****, but will have a damn tight car to show for it. My hat is off to you.

Turbo Timmy

shoulda weighed it with the driver in the right seat just for kicks...

Taranis

Looks good! I like what you've done. It's obvious you've taken a lot of care to make the v8 swap work for you. Good Job!:

A couple questions:

1. How do you like the car with the V8 (power and handling), vs the stock rotary?

2. What brand v8 did you go with, who did it, and how long did it take?

I like the power and sound of the rotary as much as anybody, but I also love the sound of a finely tuned v8. I read a post (really a flame-war) on another forum about reliability and streetability - My personal opinion is that both can be that way, as long as their owners are knowledgeable, they tune the car right and they keep it that way. It appears this owner has done that.

WTG!

Felix Wankel

Looks like a Tuned Port Injection SBC to me.

Mykl

Very sweet ride. I've always wondered what my car would sound like with the top down and a V-8 growling under the hood.

V8RX7com

The convertible RX-7 is the heaviest car the 13B was ever used in. The US market was the only market in the world where the convertible did not come stock with a turbo (meaning Mazda knew it was underpowered, but the US has too many tree huggers, so Mazda had to drop the turbo for the US market) I was growing tired of my RX-7 with the stock high mileage rotary with loud annoying exhaust (Racing Beat no cat setup) getting beat up by guys in stock lowered Honda civics with coffee can exhaust. I wanted something quick, quiet, and cheap to maintain. I used to get laughed at by the riceboys as they blew by me, now I give the guys in Porsches a run for the money. I see a guy in this forum putting in a 13B into a Spitfire, which I think is cool as hell (powerful motor in a light car) all I have done is take a heavy car (convertible RX-7) and put in a more powerful motor in it (Chevy 5.7 Tune Port Injection), and this is called stupid? It's been a lot of work to get this motor in there and have it work right (so it's not for everyone) and I agree that the Rotary engine is part of what made the RX-7 unique, but my car gets a lot more attention now then it ever did with the Rotor motor and if I could afford to put in a 20B in instead of the V8, I would have.

SonicRaT

iTrader: (6)

I agree, nice work on the conversion. I'm tired of everyones quick to hate dumbass remarks against v8 conversions, if the rx7 is 'such a work of art' then I guess half the people on the forum ruined that with their bumpers/sideskirts and custom exhaust, thats like saying stealing is ok if nobody loses from it, but stealing is stealing, or is this just some lame excuse to make yourself feel better? Nice job on the conversion, if I didn't want to experience work with rotors, I'd do the job regardless of what pissants think should be done to my own car. Nice job, and drive hard! My rusty old chevy can do quarters in 13.6, I'd die to see what it could do in a car weighing 1,300lbs less!

rx7passion

whats causing you to have 200+ lbs more on one side of the car and in the back the oppisite but 100lbs? curious but nice job.

Scott 89t2

get some coil overs and corner balance that thing!

1918 vs 1567 diagonal.

car looks good though!

RETed

Now, before anything, I'd like to complement you on a job well done.&nbsp I don't care for V8 conversions myself, by the pics show a pretty nice car.

So far you've presented corner weights.&nbsp Sure, you've hit the magical 50/50 static weight set-up.&nbsp It goes a lot more than that.

The stock set-up had a very low polar moment of inertia.&nbsp Due to the engine being actually mounted BEHIND the centerline of the front tires, this makes for a chassis the reacts very quickly to direction changes.&nbsp There is also dynamic weight number which are not very easy to measure with typical weight equipment.&nbsp The car might've hit the 50/50 mark, but how does it HANDLE versus a stock FC???




-Ted

Turbo Timmy

I don't really know why everyone always brings up how a v8 destroys the handling of the 7 without bringing up this point.

90% (or more) drivers of RX-7's never even push their car to the limits of handling. I've driven my car very aggressively on the street many years but never really pushed the limits until I was lapping Homestead Intl Speedway. I don't care what anybody says, you cannot drive your car as hard on the street as you will on a track. It's totally different. So... bottom line is most drivers aren't going to probably even notice much of a difference unless they take it to the track and end up pushing into the weeds.

Also I thought that the 2nd gen handled great then I rode in a 3rd gen around Sebring... wow!

I still want to drop a v8 into my GXL auto. though...

Snrub

iTrader: (1)

I still want to see some numbers, on an RX-7 with atleast a similar V8. (I'm not trying to be pro or con, I'm just curious)

Icemark

I agree here, this is an alarming amount of weight on the drivers front side, and would very much wonder about the balance.

with the driver that is a radical difference. If I can notice a difference between a 100 lb passenger or not, 250lbs should almost require a new spring, to retain balance

Thanks for posting those numbers, it without doubt now confirms to me that this sort of modification is not for me, and a rotary is a much better choice for me.

BlackSport0187

No I didn't miss anything thank you very much. I was directing that more at some other V8 RX-7 owners, the few I've read about that just drop in a beat up old V8 and don't bother moving the battery and so forth. Then they claim that there is no adverse effect on the handling. Yeah, whatever you say dudes.....

BlackSport0187

By a "work of art" I mean the body styling. The people who do add body kits and all that are just personalizing an already beautiful car design. What the hell does custom exhaust have to do with anything? How does that ruin the "work of art"? Was that even a coherent statement?

For some one so quickly to refer to others remarks as "dumbass", I thought you would have thought more before you talked. What's that about stealing? Did anyone catch that simile? I didn't think so. Oh, and I don't need to make myself feel better, my non-V8 engine already does that. lol.

Don't get so worked up, it was only my opinion dude.
Ike