rxtuner79

iTrader: (1)

Judging by the "Highest NA Power" thread, I am making no torque compared to the other 13b guys that have less power than me. Here is the link to my info/mods: https://www.rx7club.com/time-slips-dyno-128/my-1989-na-dyno-quarter-mile-info-702674/ Can anyone explain this?

Roen

iTrader: (2)

do you have a higher redline? What's your average power over the range?

Latin270

Could be the port work. Are the exhaust sleeves still on? Aluminum flywheel?

BlastinSideways12A

Do you have any info regarding ignition timing and fuel tuning? Are the auxiliary port sleeves functional or did you tie them open or leave them out?

Looking at the torque curve:

1) you are using the VDI (GOOD)

2) you seem to be making near stock numbers for peak torque

3) you are making about 25 horsepower more than a stock car, 30 more if you redline at 8,000

4) while your torque curve looks almost stock until approximately 6,500 RPM, it slightly tapers off rather than diving

What it means to me:

Your horsepower is coming from your engine's ability to CONTINUE to make almost peak torque until 7,500 RPM. It may even continue until 8,000 RPM.

With data regarding your ignition timing and your air-fuel ratio at various RPM levels I could tell you more about where more torque may be hiding. If you are running a stock ECU you are probably running really rich at high RPM which will drop your torque quite a bit. The reason you would still continue to make power is that you're simply flowing more air.

Your BIGGEST factor by FAR in power is the fact that you have a stock exhaust. A better setup (header, no cats) will yield CONSIDERABLE gains from 5,500 up. I would estimate peak torque in excess of 130 ft*lbs peaking around 6,500. Your power should reach upwards of 170whp with the exhaust and fuel tuning.



That dyno graph is very good. It shows that NAs CAN have linear torque curves and it also shows the great potential that your setup does have with a few minor mods.

GtoRx7

iTrader: (5)

The mustange dyno is also making the torque/power lower. figure a near 8-9% gain on a dynojet.

rxtuner79

iTrader: (1)

Thanks for the responses everyone.

The timing and a/f are stock, the exhaust diffusers are still in, and I have a Fidanza 8 lb. flywheel. The flywheel is supposed to make it harder to start off, but once you get going it actually is supposed to free up hp/tp.

My ports are wired open, but they open normally at 3800 anyway, and the dyno starts at 4000 so that shouldn't be affecting anything.

My next upgrades are going to be TII brakes w/ ss lines, sway bars, bushings, and a depowered steering rack. After that, I will be buying an SDJ header, Bonez high flow cat, and probably a Corksport catback. I will get it dyno'ed to see what I gained, but it may take a while to save up enough.

I was thinking of getting an SAFC, but I would like to go standalone/ITBs to eventually to get rid of the AFM. After I can get another daily driver, I will be stripping and turning it into a designated track car. I also want to go standalone in case i ever need more power and decide to go bridgeport or small turbo. The reason I don't want an SAFC is because I don't know if the standalone will get me a lot more power than it, and I don't want to spend a lot of money on a little gain. Let me know what you guys think.

Roen

iTrader: (2)

the flywheel will free up hp in the sense that you'll have slightly more to the wheels in the curve, but since it's not actually affecting air, fuel or spark, it doesn't change the peak power that the motor will produce.

You can use an Rtek as a good stopgap, eventually, the 2.1 will have AFM removal, and it's about $100 more than an SAFC. It allows tuning of both fuel and timing, as well as accommodating some larger injectors.

If the car sees any street duty, I would think going with the RB road race would be the best, unless you need to pass smog.

I haven't heard of the SDJ's durability, I've heard some negative stuff on the Speedsource and ISC Racing headers for their durability. They make great power though. SDJ, upon hearsay, does make more power than the RB collected header though.

rxtuner79

iTrader: (1)

I know that the flywheel doesn't affect power made by the engine, it's just less weight to spin so more power can be sent to the wheels. Wouldn't that still affect my power all over? They say that a lightweight flywheel frees up 10-12 hp, which makes sense because if you factor a 15% drivetrain loss from a new 160hp motor, you get 135 rwhp. Plus 10-12 from the flywheel and maybe a little from the ports = my 149 rwhp.

I don't really know anything about the Rteks, I never looked into them. I always thought it was an S4 thing for some reason. What are the differences between an RTek and a standalone?

Passing smog isn't a problem because someone I know works at a garage and can get me through emissions and inspections.

I have a thread going in the 2nd gen section, and the info there has made me decide on the SDJ header. Once I have it for a while, I can update everyone on durability.

GtoRx7

iTrader: (5)

I would doubt that the less rotational mass from a lightweight flywheel is 10-12 hp. I would say closer to 1hp or less on the dyno. Flywheels do not change hp, or torque. It simply the same effect as removing weight from a car. Less mass to accelerate, gives the "effect" of extra hp. This will not show up on a dyno, at least, barely show up.

Roen

iTrader: (2)

It won't show up at all. Flywheels give 0 hp more than the engine is already capable of producing. Ask yourself, if you take off your rear seats, do you gain any hp?

If it does not alter air, fuel or spark directly, it will not impact peak hp. it's basic thermodynamics.

Rtek is a reprogrammed ECU, so it's plug and play, but it's really really good. www.pocketlogger.com

rxtuner79

iTrader: (1)

I actually just looked into the Rtek a little bit, and that will most likely go on after my exhaust.

I see where you're coming from with the back seats example, but the engine is not turning them directly. If your car loses 15% of its hp from the motor to the wheels, then wouldn't you gain some of that back by removing weight from the drivetrain? Basically, the engine will still make the same amount of power, it can just get more of it to the wheels because some of the power used to spin a 20+ lb flywheel can now go directly to the rear wheels, thus freeing up hp to the wheels. And since dynos measure your hp going to the wheels, wouldn't the flywheel have an effect on the rwhp numbers? Or am I seeing this completely wrong?

GtoRx7

iTrader: (5)

Well, when measuring hp to the wheels, it is taking into account for any loses. Loses are friction, and also rotational mass spinning among other things. This why sometimes in certain transmissions, more power will be realized when being dyno'd in 4th gear. 4th gear in a Rx-7 isnt putting pressure on the gearsets, giving less friction. More rotational mass, requires more power to keep it spinning, therefore will lose more power/torque to the wheels. So on a chassis dyno, I think it could produce a minor effect on power/torque going with a lighter flywheel. But it has to be very small.

Roen

iTrader: (2)

That's talking about gear ratios, which multiply wheel torque, which is a totally different matter. You should always dyno in a gear closest to a 1:1 gear ratio. You can multiply your power by dynoing in 1st.

To be honest, I'm not 100% sure, but from what I've seen, gains from a lightweight flywheel converge to 0 as hp goes to peak hp along the curve.

diabolical1

iTrader: (3)

bingo! it is small, but it also seems to be proportionate to the engine's (setup's) peak. if i recall correctly, i think i saw a dyno that showed as much as +8 HP - i want to say it was an MR2 Turbo making ridiculous power several years ago.

Roen

iTrader: (2)

I would believe the effect to be more noticeable as your accelerating from lower rpm, but that, since your top speed does not change, I would not think your peak hp changes, since hp and aero govern top speed.

GtoRx7

iTrader: (5)

You are right about gear ratios changing rear wheel torque. However on the dyno, you are incorrect. Dynos all use a reference to engine rpms vs wheel rpms. So that they can display a fly-wheel-torque with drivetrain loses. If you were to watch the crude numbers (which alot of dynos can do, such as dyna-pack) Then 1st gear would display 1000's of ft-lbs, but then once you divide it by the rear end, and transmission ratio, you will have flywheel torque with drivetrain looses. That is why the figures everyone is used to seeing is in fact a mis-leading number, but the generally accepted value.

Roen

iTrader: (2)

the important thing is dividing by the transmission ratio. If you can alter that ratio in the dyno's computer, you can artificially inflate numbers.

dj55b

iTrader: (2)

your stock ignition timing could be throwing things off. When i was on the dyno last, playing around with my distributor advancing it and stuff, I saw a difference of 10hp just playing with timing. You have to advance it properly to match your intake timing. This is all trial and error to get it right on for maximum power. I'm curious why you didn't port your Exhaust while you were at it too? It only makes sense if you make one bigger to make the other match it also.

Btw i'm making more torque with my 12a than your 13b. almost 10ft=lb, and thats which the engine not tuned properly neither.

As for SDJ headers as I have them myself, and can say they're been reliable for me all this time.

rotormind

In the intake manifold, there is a rotating cylinder that opens and closes the runners. I dont know exactly what its called, but it is activated by air and has a lever on the outside of it. I think it control the runners for the 5th and 6th port. If its not working properly, it will stay up and close the runners and you will loose alot of power.

Dont know if this is your problem, but i noticed a big difference in power when I disconnected the rod and pulled the lever down.

Roen

iTrader: (2)

the 5/6 port activation is aptly named, 6 port induction. That helps boost low end torque. When I was messing around with my Rtek, I found that by keeping the 5/6 ports closed as long as possible, I made the most low end power on the dyno. I think I have them opening 4200-4400 rpms. However, judging by the graph, I think your 6PI working.

There's also another system that's critical to power, called VDI. I believe it uses the harmonic resonance of the intake manifold to boost airflow at high rpms. If this system is not working, it will seriously impact your peak hp.

rxtuner79

iTrader: (1)

I'm actually pretty impressed with my hp... just not so much with the torque.

The 5th and 6th ports have been wired open, and I'm assuming the VDI is also working. As you can see, it pulls pretty well to the redline.

The exhaust ports were also ported, but the diffusers were left in.

dj55b: If the stock ignition timing is holding me back (which I'm not arguing), how come everyone else with less power is making more torque? I doubt that they all have their timing advanced. Also, you probably make more tq than me because you have more work into your 12a than I have in my 13b, which I actually love to see. I also have an SA, but I can't modify it because it's a show car and I want to leave it stock. It sucks because it's amazing how fast those cars can go with such a little amount of work.

dj55b

iTrader: (2)

i'm pretty sure that anyone that does porting will mess with their timing. You could also look into getting a megasquirt for a cheap standalone to get the max out of your engine tune control. My car isn't moded that much as you might think.

A good header will result in good torque. The SDJ header that I have is partially due to my high torque in my engine. Some people used to call the SDJ the torque monster lol. Its a very well designed header and shame they went don't produce them anymore. Once I'm done my welding course, I might actually try to contact Robert from Rotary shack about rights of reproduction of the header see if he can direct me in the right direction. I would like to have them reproduced, or even send them out to a company that does them in Inconel.

rotormind

I know that keeping his 5th and 6th port open wont help with low end torque. But if the cylinder in the intake mainfold is blocking the runners for the 5th and 6th port, then the ports are not being used. If his air pump is off, then the runners are definetly closed because the spring holds the lever to the cylinder until enough air can open it. If I had pictures, youll see exactly what im talking about.

Im saying this because i had almost the same setup as you but my streetport was very small. Your car should be faster than mind but by the looks of your 1/4 mile mph, you are slower. If you can pull on an 06 rsx type-s on the highway, than you are very close to where you should be at.


This is all from my experience. Besides, a stock rx7 should make that kind of power with an intake and exhaust if everything is working properly. Your only making about 15 more hp from stock.

Its easy to do and it wont mess up anything. On the right side of the intake, you'll see a tiny E-clip holding a rod to the lever. Pull off the clip, release the rod and you will be able to pull the lever down. I garantee you if this lever was up the whole time, your gonna notice a difference in power and you will get more torque, but not at the bottom end.

dj55b

iTrader: (2)

won't even hurt if you wish to go with the pineapple racing inserts neither to give you a few more ponies. and probably torque

Roen

iTrader: (2)

do we even know if those sleeves actually give ponies? From what I've seen, they don't really do much and they risk trashing an engine if they fail.