Let's talk weight - Page 2 - RX7Club.com - Mazda RX7 Forum

Let's talk weight

Old 06-03-18, 10:29 AM
  #26  
Junior Member
 
Join Date: Feb 2016
Location: Fort Campbell KY
Posts: 10
Thanks: 0
Thanked 0 Times in 0 Posts
Its funny that that there is no easily accessible definitive answer, I've seen a couple claim the same and or marginal weight gains with the ls when staying in race trim (no ps or abs on an all aluminum setup).
I've even got 1 thread I've seen that full ac and ps setups tipped the scales 27 pounds over rotary weight, with about 50-60 pounds more on the read axle and the front actually being lighter (due to a majority of weight being low in the transmissions area).
Jefftopgun is offline  
Old 09-18-18, 08:14 AM
  #27  
Junior Member
 
Join Date: Sep 2018
Location: ON
Posts: 14
Thanks: 0
Thanked 0 Times in 0 Posts
I have a full belt 87 FC race car with a SBF and T56. Dry weight is 2590 and weight balance is 53F/ 47R. I could probably take maybe 60 to 70 pounds more out of it. With fuel and driver weight its 2845 LBs. If I had used an aluminum LS I'm sure I could have the car at around 2300 and change dry and better balance of course.
patrickm is offline  
Old 09-18-18, 04:25 PM
  #28  
Lives on the Forum
iTrader: (9)
 
BLUE TII's Avatar
 
Join Date: Mar 2001
Location: CA
Posts: 7,005
Thanked 131 Times in 115 Posts
Jefftopgun

Its funny that that there is no easily accessible definitive answer, I've seen a couple claim the same and or marginal weight gains with the ls when staying in race trim (no ps or abs on an all aluminum setup).
To get the definitive answer one would have to buy a scale, buy the parts and document the weights.

However, most all the people doing LS V8 swaps into RX-7s aren't obsessed with weight, so they don't bother to document weight that precisely. They just want an RX-7 with plenty of reliable power and smog legality is a big bonus to some.

I was more curious about weights than V8s (heyyyyyyyyyy), so I purchased a high capacity digital draw scale (they are cheap now).
So far I have learned my full accessory, stock 13B-REW with oil/coolant drained and no downpipe weighted 407lbs ( I was expecting 420lbs). Results will vary.

Here are links to an FD owned by a someone obsessed with weight and rotaries if you are interested-
2385lb "full interior" (modded interior) single turbo street FD

https://www.hoonigan.com/blogs/daily-transmission/super-light-1994-mazda-rx-7-r2


https://www.rx7club.com/build-threads-292/fd3rs-recap-thread-1130035/



BLUE TII is offline  
Old 09-18-18, 04:59 PM
  #29  
Penis Healthy
iTrader: (5)
 
FührerTüner's Avatar
 
Join Date: Jul 2013
Location: █▬█ █▄█ █▬█ █▄██▬█ █▄█ █▬█ █▄█
Posts: 1,978
Thanked 42 Times in 38 Posts
Originally Posted by BLUE TII View Post
So far I have learned my full accessory, stock 13B-REW with oil/coolant drained and no downpipe weighted 407lbs ( I was expecting 420lbs). Results will vary.
Holy shmolies! They were right!

Originally Posted by FührerTüner View Post
Ive heard in a FC, LS1 weighs 100lbs more than a 13bt, aftermarket turbo with a FMIC setup.

FührerTüner is offline  
Old 09-18-18, 08:37 PM
  #30  
Lives on the Forum
iTrader: (9)
 
BLUE TII's Avatar
 
Join Date: Mar 2001
Location: CA
Posts: 7,005
Thanked 131 Times in 115 Posts
Yup!
Fully dressed LS V8 engine (497lbs) is right around 90lbs more than a stock fully dressed 13B-REW engine (407lbs).

Now, it is a LOT easier to take 150lbs off the 13B-REW rotary engine than the LS engine if we are talking modified engines...
BLUE TII is offline  
Old 09-19-18, 12:23 PM
  #31  
Rare for a Reason
iTrader: (13)
 
Narfle's Avatar
 
Join Date: Nov 2002
Location: Dagobah
Posts: 5,387
Thanked 78 Times in 57 Posts
The 13b is also shorter (farther back in the bay) and the CG is lower. But, I doubt 95% of people could care or tell about the weight difference.
Narfle is offline  
Old 09-22-18, 08:22 AM
  #32  
Penis Healthy
iTrader: (5)
 
FührerTüner's Avatar
 
Join Date: Jul 2013
Location: █▬█ █▄█ █▬█ █▄██▬█ █▄█ █▬█ █▄█
Posts: 1,978
Thanked 42 Times in 38 Posts
I heard about the weight ratio, is the LS1 takes it from 50:50 to 51:49, which really should be hardly noticeable. Not sure how to calculate it.
FührerTüner is offline  
Old 09-29-18, 12:34 PM
  #33  
Lives on the Forum
iTrader: (9)
 
BLUE TII's Avatar
 
Join Date: Mar 2001
Location: CA
Posts: 7,005
Thanked 131 Times in 115 Posts
BLUE TII quote-
my full accessory, stock 13B-REW with oil/coolant drained and no downpipe weighted 407lbs ( I was expecting 420lbs). Results will vary.
I weighed my modified 13B-REW again before putting it in.

360Lbs
Power steering and simplified stock sequential turbos.
Weight reduction- emissions delete, AC pump delete, lightweight pulleys, manifold porting, dirt/grime removal.
Weight additions, enfini Y-pipe, Greddy TB elbow, Winchester oil Pan, updated iron LH motor mount, 8 cans of satin black paint

The takeaway is an emissions strip and AC delete takes 50Lbs off a stock 13B-REW.
BLUE TII is offline  
Old 10-14-18, 08:32 PM
  #34  
Senior Member
 
Join Date: Oct 2013
Location: Clemmons, NC
Posts: 614
Thanked 18 Times in 15 Posts
FB with Iron Block

My FB with a LT1 and heavy 17x9 weighs 2477lbs
Freeskier7791 is offline  
Old 12-03-18, 07:09 PM
  #35  
Can Post Only in New Member Section
 
Join Date: Dec 2018
Location: IDAHO
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
1st post for me mine is a bit heavier
my 84 Rx7 weighs 2920lb with me in it and about 1/2 a tank of fuel.

455 Pontiac . 200-4R trans
headers, dual exhaust, aluminum intake
manual steering
stock 13" tires wheels
full interior
Jegs aluminum radiator

Last edited by 455dan; 12-03-18 at 08:03 PM.
455dan is offline  
Old 12-03-18, 10:56 PM
  #36  
Rotary Freak
iTrader: (10)
 
Join Date: Mar 2001
Location: San Francisco, CA
Posts: 2,055
Thanks: 0
Thanked 3 Times in 3 Posts
Originally Posted by FührerTüner View Post
Holy shmolies! They were right!



That username is awesome! The engine weight with a manual transmission can easily be lowered with aluminum flywheel... Back in 2005 I had a heads/cam LS1 making 440rwhp and it was pretty much 50/50 with 285/30/18's at all corners and 2800lbs with a heavy dual 3" mild steel exhaust and stock body panels. On the skidpad it did 1.13g's and handled great with fast turn in.

I used to own a full race wide body FD on 320mm Hoosiers at all corners/CCW C10

18x12's, 438ci LS7 with G-Force 4spd dog box (80lbs) running a 14lbs clutch/flywheel.... fully gutted, fiberglass doors, fulll cage, tubed front clip, CF hatch, lexan front/rear windows, no side windows, no a/c, basic aluminum dash with display.. and it was 2470lbs with 8 gallons of fuel. That car ripped on the track. This picture is when the new owner had it and repainted the car plus added some front aero work.... did a MAST Motorsports $20K 416ci engine, Quaiffe sequential trans, and other goodies! The car had about $100K into before he bought it... then he put easily another $40K into it after I sold it to him.

Last edited by gnx7; 12-03-18 at 10:58 PM.
gnx7 is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
MILOS7
3rd Generation Specific (1993-2002)
6
05-09-16 07:39 AM


Thread Tools
Search this Thread
Quick Reply: Let's talk weight


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: