Hello again. I'm not joking about running 9's. I'm going the LS1/T-56 route. So like I said, motor and tranny are taken care of. My current car, an 01' WS6 is making 750hp on pump gas so I know how to build a motor that makes power. I'm new to RX7's however and was wondering what it's going to take drivetrain wise on these cars to run a 9. What are the week points? Thanks to the few of you that actually responded with out doubting me or making a stupid comment. And why did my other thread get closed? Thanks again.

 

boostat4500,

There are hardly any people running 9's here on the forum (at least in full street trim). Frankly, most people here don't care about drag racing that much. I gave you a link to a company who has done it in full street trim. They are the best people to talk to as they can speak with experience from having actually done it as to what needs to be done.

 

Ok, thanks. I'm just trying to get a feel for what the week points of these cars are.

 

Damn dude, what did you do to that LS1 to get it to put out 750hp? Thats way more than just heads and cam...Possibly a blower, or twin turbo set up? Please dont say nos...

 

It's a 408 stroker with a Procharger D-1SC at about 9lbs of boost. In the RX7 I'm either gonna do a Turbo or NOS to keep it a little more stealth.

 

I think your questions were answered pretty well in the first thread. I wondered if the thread was closed because of my last comment there, which was unnecessary, but could have been insightful to your quest for knowledge, but also could have started a shitfest. Again, I think your questions were answered, and I apologize because I did have some doubt about your technical abilities. It appears you're much further along than I gave you credit for.

 

Actually, I think you could use some more insights about setting up the suspension, but my knowledge here is pretty limited. When I bought my car, all the work was done by the previous owner, so that's one area I haven't had to research myself. Maybe someone will chime in here to help you on this.

 

The suspension specs for high 9second street trim rx7 are listed here on page 4 and further discussed on page 8:
http://rx7.com/images/street_heat.pdf

 

https://www.rx7club.com/group-buy-center-69/gb-proposal-cobra-cradle-rearends-jimlab-471127/
https://www.rx7club.com/showthread.p...ight=live+axel
and last is to upgrade the to a kazz and some 300m axels. You need some good diff bracing and upgraded bushings for the diff and trailing arms.

 

someone in the previous thread stated "Kaaz=****", well I disagree. I don't know if it's any better or worse than the Ford diff he uses, but it ain't "****". Mine has held up after extended abuse, and it's the same one they use on the car featured in the Rotary Performance article. Many a Formula D champ uses them, too.

THis is from RX7.com:
The 3rd generation RX-7 comes from the factory with a high-tech Torsen Limited Slip Differential. This unit is superior to the earlier viscous and mechanical limited slip differentials in many ways. Quieter operation, better torque transfer, and no additives to install in the gear oil. The only problem with the units are that they are not rebuildable, and not extremely durable. For your standard street car, this isn’t much of a concern but for cars that see regular track duty, whether drag race, autocross or road racing, a reliable differential is worth the investment in a high quality mechanical differential.

We carry the extremely high quality and durable KAAZ Racing Limited Slip Differentials. KAAZ is the leading manufacture of differentials in Japan building them for Japanese manufacture work teams such as TRD, Nismo, STi, etc. This is the same differential we've been using on our own race cars and we're happy to report NO failures in countless runs. If you’re looking for something to handle the abuse you give it on the drag strip, road course or the street, this is the one we choose.

 

found here: http://rx7.com/store/rx7/fdsuspension.html

 

I think the entire car is weak when it comes to drag racing. The RX-7 is a purpose-built car, and that purpose is without a doubt for superior handling on the roadcourse. Dragging - especially w/ significant power to the wheels - is gonna destroy pretty much every driveline component the FD has, one after the other. There's no way around it. The hardcore dragsters we have on the forums have managed to break every component imaginable...

 

I believe you get around it by upgrading with aftermarket parts. Seriously, what can't be gotten around by using aftermarket purpose built parts? The hardcore roadcourse guys aren't still on their stock components. In stock form, yes, it's a better roadcourse car, but with purpose built aftermarket parts you could make it anything you desire.

ps- ever seen that video of a yellow school bus pullin' wheelies down the drag strip?

 

If you really wanna run 9s, youre going to have to get more displacement (v8, or 20b, the latter being megabucks) or if you stick with the 13b... get a HUGE turbo, with alky or water injection, and race gas. IMO cheapest way is just get a v8. I know Im going to ruffle feathers, but hey, what do you want more? The single digit or how you get there? Even if you have a 400+cid engine drop in your lap (which is like 6.6 liters) its still going to be a little pricey to get the power generated and keep it reliable with that displacement. With a smaller one, hey, hope you got money!

As far as suspension, Ive seen the T-II rear take a 383FC into the 9s (and humiliate a supra..) so Im fairly sure if the FD rear was set up properly it could do it. Oh, and you cant go get lowering or or track springs on the rear of the car and expect to launch. Weight transfer to the rear is one of the facts of life tuning for drag launches - what you want with rear drive.

Ive heard of guys going with solid axles, and when you get into MEGAPOWER that might be a good idea if this is going to be exclusively a dragracing car. Double wishbones arent really a necessity when dragging and can start to work against you later on down the road - oh, and torsens are good LSDs, but if you get wheelhop the wheels load and unload... not fun. Go ahead and get a clutch type - which are also REBUILDABLE and can be preloaded so it stays locked if your car raises a hind leg. Solid axles are also lower in weight OVERALL than the double wishbone assembly, but the unsprung weight is higher.

Oh, and getting one of those beefy built up automatics probably wouldnt hurt either, same for weight reduction. The FD is light and aerodynamic to begin with, which will work with you. Just expect to step on a lot of peoples toes with this project and realize the technical limitations of using a doublewishbone sprung car thats really meant for twisties with a 2.6 liter turbo engine and a frame thats made as light as possible - have you seen whats happened to some people's floorpans using Hinsons v8? They pulled the floorpan out! The FD isnt a flexible or weak car, but its built just enough for what it was intended for - oh, and use a damned crossmember to mount **** when youre trying to drag... lol

Oh, and of course you need a cage, helmet, fire extinguisher, cutoff switch, drag slicks and wheels, yadda yadda yadda.

 

Well since you had a 750Hp ws6 i expect that you realize the suspension will need some major work. Some kind of fully adjustable coilover or something along those lines i would imagine. If i was you i would wait for jimlab's solution for an engine cradle but that is just me. You may be making your own cradle for all i know. You will need to upgrade your rear diff. there are a few routes for this KAAZ, a TII setup or jimlab's cobra setup all have there positives and negatives. Other than that i really dont know much about running 9's as i am hoping for high 10's at best with my v8 and the car will mostly be used for auto-x and road course

 

Thanks for the help everyone. From building the 408 in my car now I am familiar with what it takes parts and cost wise to keep it reliable. I've put 18k on my motor in 13 months ( it's my daily driver ) with no issues. The part thats new to me is the independant rear suspension. I know how to make a solid axle live but not independant. The fact that these cars were designed more for handling is what draws me to them, and the fact they're so light. ( my TA weighs 3700 w/o me in it ). I want to kick *** in the corners and the straights. So it basically sounds like plan on replacing everything in the rear end, correct?
III GEN X : Thanks for all the links and no hard feelings.
By the way, my TA is for sale if anyones interested.

 

Great! Here's one last link with several relevant pages of discussion:
https://www.rx7club.com/showthread.p...1173&highlight

 

boostat4500...here is a link that you will need to get all your info for your convertion.There is not alot on love on this site for the LS1-FD convertion.
99.9% of the guys here are rotary lovers.
I'm suprised you havent got bumbarded with hate mail because of your post.It is possable to get 9's from your FD and is a sweet car for the drag.Brian Hinson gets high 8's from his twin turbo LS1.I think I have the video.It's better on a road course for sure but I'm sure you know that.I got 10'9's from my FD with only heads and a mild cam.I wont let the cat out of the bag because there is some poeple I dont want to know but I will be 9's soon enough

http://www.torquecentral.com/index.php

 

Haha, im liking the flash animation. ps. good work with your ls1 swap. Runnin 10.9's and still lookin close to stock on the outside is quite a feat!

 

Thanks for the props bro.Not alot of love for the LS1 swap on the site.So much easier to got so much faster with a LS1.
25 MPG with 421WRHP and hell of reliable.

 

Go for a build thats flexible (not too peaky) and use NAWZZ to go for the drag times.

9 second quartermile time power might be a *LITTLE* overkill on an autocross. and on a road course would basically necessitate some aero **** for safety reasons, a cage, and some mongo brakes... and big *** tires. In other words... time to get a race liscense and training and life insurance.

 

Hrmmm

 

As a matter of fact...I believe Hinson is running high 8's last time I heard.
I think it's more likely to get 9's from a LS1 then rotary.I'm not knocken the rotary but the reason you probaly see more rotarys running those times......if you do, is because 99.9% of RX7's are rotary.If there is a 9 second rotary....you think your going to see it on the street.....NO.

 

LS1240z - its a fact of life that a 13b isn't a large displacement engine. Its the equivilant of a high rev-intended 2.6 liter 4banger if you tried to compare to a piston engine.

A 9 second street car that does not easily make!

It would be much easier and streetable with a v8, esp in such a light car, but if you got the money and the rotary fanatacism a 20B could work. Equivilant of 4 liters isnt exactly unable to spool a turbo

 

And why wouldn't you see a 9sec RX7 WITH A ROTARY on the street??? Take a look at one. lol...In all seriousness a LS1 has no better chance of running sub 10 sec. passes than a rotary. Plenty of rotary's running 6's and 7's. So NEXT question!