Hi, I have not yet gotten an FD but I will for sure in the middle of 2009, so I'm trying to prepare and study ahead about the car.
As I mentioned somewhere before, I had some experience with 240SX wich was only limited with single turbo setup. I am wondering what turbo setup (sequential or single) has better torque distribution in mid-high RPM range of FD. I searched a bit but I can't seem to find torque related discussion. There are a lot of horsepower discussions but I am not very interested in HP.

 

This is an old page where you can compare some known setups:

http://www.catenet.net/dyno.php

 

Rotary motors dont produce alot of torque...they produce HP but no torque....

 

That applies to most Japanese engines. Honda for instance produce quite nice HP range but their torque is like on the way bottom. I'm guessing higher RPM gives more HP and less torque. I'd like as much torque as possible that Rotary engine can produce. AND since FD engines are FI engines, I'd wanna know what kinda turbo setup has the highest torque.
I believe that stock FD has 255HP with 215ft-lb of torque. I'd like to get my FD set up to have about 300ft-lb of torque but I'm not sure if it is even possible. I'm just not familiar with rotary engines at all.

 

https://www.rx7club.com/time-slips-dyno-121/dyno-graphs-229717/

 

you can get 300 torque for sure, but not without at least 400hp

 

I got 300 torque with just bolt ons on a stock port motor.. on stock turbos..
but I don't know if the torque comes early enough in the powerband for your liking tho
as mine is non-seq. if you leave it sequential you'll have about 200 ft-lbs to the wheels by 3,000 rpm

 

In case anyone doesn't know HP is a calculation of torque...

(TORQUE x RPM) / 5252 = HP

Torque is what gives you horsepower, not the other way around.

thewird

 

^^ Nice Do you have the dyno run files for those plots? Would you mind sharing with me? I am trying to collect as many of the run files as I can for comparison purposes. Thanks :-D

^^ Yep. I think a lot of people forget that torque is what accelerates the car in the first place. HP tells you how much that torque is put to good use however

 

Ottoman, that's exactly the data I want! I'm actually leaning toward the secuential setup, but non-seq doesn't sound bad at all looking at your graph. Thanks!

Yes, I also understand the importance of HP, but what I want to know is how the torque band differs depending on the different turbo setups. Then I'll have a decent idead of what setup is right for me.

 

Wow I didnt know something like that existed! As usual YOU ARE ZE MAN!!

 

Why are you interested in the torque numbers? Especially if looking into an rx7 which really don't make much torque. If you want an rx7 with torque you should be looking at v8 rx7's. If you want torque for a good street car with good response and are set on the rotary engine you can't beat the low end response of the sequential twins. More important then peak torque numbers is at what rpm the car makes its torque. A very high torque rotary will most likely be sluggish in the lower rpms as it would take a bigger turbo to make the numbers which means more lag. You should tell us what you want from the car to pick the best combination for you. Torque basically is telling us work is being done, hp is telling us how long it takes to do that work. If i were to say i can move 50 lbs of brick that may not seem like a big deal, but if i add the amount of time it takes to move it that makes a big difference.

 

at the time I didn't actually realize I could take the dyno files..

I didn't think they would be of any use since u can see the data on the final Graph

next time i'm in the area I'll have to ask for them..


what do u use them for btw?

 

True.

But what about cars that have more torque than hp? Like higher displacement engines like the v10 in the viper? Their TT kits give them like 1100ft lbs and like 950rwhp.

 

RPM is the other factor. Those big blocks don't rev as high to make power.

thewird

 

To make a long answer short: thewird is 100% right.
So that tells you, that the force you are feeling and what you are looking for in the end, is Power. Not torque. But Power is the result of the before told equation. so youre question has to be.
Do I search for a special power @ a specific rpm??
So there the short answer has to become complicated.
BUT to shorten that again. I´ll give you an explanation which is not 100% but one way to go.
If you want to find torque, add timing! Thats an easy rule...
BUT your whole engine has to have the right environment to add timing.
What means:
All what gives you "the need" to add timing is what helps to get torque = power.
Easiest way = increasing boost.

So if you want to look for best power in high rpms --> large single turbo... that easy.

I hope that helped, mate...

Kind RE gards
Marc

 

http://www.dynojet.com/downloads/software.aspx to view the dyno run files. It's a pretty simple program, you'll figure it out in 15 minutes.

 

i see very many good responses here, but if i understand his question correctly... i think he's using the correspondense *spelling* of torque = engine reponse in the fullest range possible of the engine.

if i'm wrong forget this rant, if i'm right i'll try to help ya.

personally this is how i felt with my rx-7 when i built it. i was said "torque" instaed of a high horsepower number, and as mentioned above, loads of lag due to a big single turbo. i opted to keep the twins, stock or BNR's. but i found i was simplicity. twin are truly great designs! but i hated the rats nest, even the simplified, and ididnt' like 20lbs of iron bolted just radiating heat everywhere, and 3k for a new set... screw that. so i chose the ladder, a single.

since i wanted said "torque" and response i had a-spec help me build a kit. most fella's here when using a gt-35r choose a .94 or 1.04 hot side. good hp, a bit of lag, but the numbers are there. i personally loved the feeling of hte twins, where at any given time i could pass in traffic or have fun, not wait for the lag. with their help i chose actually a gt35r with a .74 hot side, though a few here have called me a fool for such a small hot side, i love the torqy <-- spelling again, of the quick spooling. i run a 10psi spring, but recieve 12.5 psi at the manifold. I'm an odd ball, so i go against normal theory. really study the maps, and research how the maps work vs hp vs spool time etc. took me about 2 months to decide which turbo i finally wanted. good luck buddy.


BTW, i love takign off or 80% of my cars from a light or the highway... problem i run into..... is when that supra finally does spool his big *** turbo... that 4 car lead fades really fast... LOL

 

did he just compare our 7's to hondas?

 

They both have engines, tires, brakes, seats, etc..


Tyburn, when picking a turbo there is more to consider rather than just torque or usable power. Think about efficiency. What I mean is that if you pick a turbo which you need to run at a higher efficiency to get the numbers you are looking for, then you are removing reliability from your setup. The harder you run a turbo, the more heat you generate. The more heat you generate, the more you risk situations like pre-ignition. The ideal situation would be to pick a turbo that you can run a lower boost to achieve your goals.

i.e. if you pick a turbo than can generate 19 PSI. However you run it at 12 PSI which still achieves your goals, then you'll have a much more reliable setup. Your charge temps will be cooler and your cooling system will not need to work as hard to keep the overall engine temperature low.

I would suggest checking out Corky Bell's book on turbos:

http://search.barnesandnoble.com/Max.../9780837601601

A lot of good information there on how different aspects of turbo components can effect your performance. Also, take a look through the thread I listed above. You'll see various setups and the power they make.

 

Thanks a lot for great responses guys!

You read my mind Nat6c, I want as much engine response as possible. I'm kinda sick of the lag of single turbo and not being able to get the full response when I want it.

Thanks Mahjik, you help a lot with tons of data, I can at least see where to start now. There is A LOT to study... sequential is quite foreigh to me as well as rotary engine. RX-7 seems VERY unique and strange, but it's already getting fun haha.

 

In it's time the Cosmo 20b was the torqiest engine from japan.

Any medium single turbo should give you a combination of response, torque delivery, and decent peak power. +1 on the turbo dyno comparo page. (lol assonance)

 

But higher displacement engines will always have more torque regardless no? Regardless of rpm.

It only makes sense.

I.E. A 6.0 liter v8 @ 4500rpm vs a 2.0 liter 4 cyl @ 4500rpm. (comparing these 2 because they are out of peak range anyway)

I know rpm is a factor but also displacement correct? And then what about gear ratios?

This is confusing lol

 

it's not neccesarily Displacement that makes the torque..
it's the Long Stroke of the V8's that give it the Torque..



for example.. an E39 M5 like mine.. actually has better low end grunt and torque.. then the newer V10 E60 M5.. both are ~ 5.0 liters

but the long stroke motors lose RPM due to higher piston velocities (E39 M5 has higher piston speed with a lower rev limiter.. then the E60 even tho the E60 revs to 8,000+ Rpm)


so simply being a large displacement isn't always the answer..

there are alot of tricks too.. such as the RX8 with it's intake manifold design...


come to think of it.. a S/C or turbo RX8 might actually meet your needs better than an FD would..

 

lol...what is that old saying, that a Timex watch has more torque at 1 rpm than a 454 Chevy.....