The Power Curve
 

I like shifting at 7000 in a sprint. Have been told the power curve drops around that. Anyone have any dyno results on a 12A or 13B SP to document the curve? Sure, I’ve taken it off the tach, but stats seem to say thats not where the max power is.

well what I've heard is that the sp engines have a different curve, more power towards the high end. I forget where I read that. But I have observed my tach goes faster from 7k to 8k than from 6 to 7k.

I noticed in my SP 12a that the motor really doesn't wind all that fast until 3500 or so, then the tach shoots up QUICK until around 7000 or so, then I shift at around 7200.

with mech secondaries that 4k-7k shot is even more dramatic. It's like a small shot of NOS.

Stock 13b RE-EGI as found in an 84/85 SE:

http://tinypic.com/1eqvb9

HTH,

What you really need to be looking at is the max torque your car can be making at any given vehicle speed. You need to factor in the gearing from the engine to the wheels for all engine speeds.

What you'll find is that even if engine torque drops off at the upper RPM ranges, you're still making more torque at the road by staying on it until redline than if you were to shift to the next gear up. This is the case for almost any street engine, there are exceptions, of course, but not many and certainly not the rotary.

With a stock port 12a I had best 1/4 mile times shifting at 8k and my freinds 12a use to be shifted at 9.5-10.5k at the track I just was not that brave. I shifted at 9k with a pretty big jump into 2nd scared the guy I was racing to. Oh I have the commom mods RB header, efan, ported intake, specaily tuned carb, holley blue fuel pump oh and the all inportant weight stripping. Oh and cdrad51 I know what you mean it is like a small shot of nitrous just don't take it to high into the revs before opening the secondarys as you don't want the engine to go to lean.

Is this at the flywheel?

I believe this is a chassis dyno reading, so you're seeing rwhp, but I could be wrong. I wish the owner of this slip would show up and claim it - I have some questions for him.

Provided here for analysis and to help show where torque 'occurs' on an SE. HTH,

That can't be stock at the wheels. It should only about 105hp on a chassis dyno. This is what I'd expect an S5 to look like stock.

That dyno is off of Tim Schuh's RX-7. Although it is an SE, he is running headers, Megasquirt ECU, and an 86-88 style intake among other mods. Here is a bit about his car:

http://www.wankel.net/registry/1st/tschuh.html

I believe that this dyno was before the MS and second gen intake as I have spoken to him before via email about his MS setup and he said with the MS and 2nd gen intake, his power at the rear wheels went from about 130 to 150 hp. A nice part of the MS ECU is that it eliminates the AFM, which we all know is a major restriction. I have seen the pics around of his engine and MS setup, but I can't remember the link.

Kent

Wow, so without even porting the engine, he's showing about 160 bhp with a dead flat torque curve. Although it looks like he's got every bolt on possible, that's impressive.

Thanks for the link and details, Addict - I've been looking for that information for awhile,

No problem guys. When I saw that curve, I knew that I recongnized it from Tim's car. I remembered that he had his dynoed at rotary performance. I found some of his newer dyno runs to show the difference of the MS vs. stock ECU. I am sure that most of that 11.5 hp that he picked up over stock was because of the removal of the AFM.

http://megasquirt.wankel.net/MS_Imag...vs-Factory.png

http://megasquirt.wankel.net/MS_Images/MS-HP&Torque.png


I also managed to find the pics that I was talking about if anyone is interested.

http://www.wankel.net/~krwright/cars...egasquirt.html

http://www.wankel.net/~krwright/cars/tims_manifold.html

Kent

-quote-Wow, so without even porting the engine, he's showing about 160 bhp with a dead flat torque curve. Although it looks like he's got every bolt on possible, that's impressive.-quote-

Yea,thats a nice flat torque delivery.
N/A injected 13Bs are famous for having an extensive,usable torque curve.Its all about the intake manifold tuning.The stock SE made peak torque (133lbs) at only 2750 RPMS! Who said rotaries have no low end grunt!
Later S4 and S5 N/A motors had a small amount more torque but it peaked at slightly higher RPMS.This was the tradeoff for higher peak HP and higher RPM limits due to lighter components.The Renesis takes this even furthur.The peak HP is WAY up from the older 13Bs,but the torque is still down there around a buck and a half.

cant wait for the next buttonwillow dyno day. My RX-3 and the FB are equipped with 13-B streetport (ported to the max) with a 48 IDA. Since the RX-3 is very light, I can feel the power from 2500 RPM and up. However, with the heavy FB, the powerband doesnt start til 4K RPM and goes up above 9K RPM.

[QUOTE=steve84GS TII]-quote-Wow, so without even porting the engine, he's showing about 160 bhp with a dead flat torque curve. Although it looks like he's got every bolt on possible, that's impressive.-quote-

Yea,thats a nice flat torque delivery.
N/A injected 13Bs are famous for having an extensive,usable torque curve.Its all about the intake manifold tuning.The stock SE made peak torque (133lbs) at only 2750 RPMS! Who said rotaries have no low end grunt!
Later S4 and S5 N/A motors had a small amount more torque but it peaked at slightly higher RPMS.This was the tradeoff for higher peak HP and higher RPM limits due to lighter components.The Renesis takes this even furthur.The peak HP is WAY up from the older 13Bs,but the torque is still down there around a buck and a half.[/QUOTE

Here's rx7.com's dyno of an S5 and an Rx-8.

Cool!
Kinda jagged there,I wonder what ECU flash that RX-8 was tested with?
That sucker holds on for quite a while, huh?Pretty decent torque still,all the way up at 8K.

A real dyno pull is very jagged. When you see a smooth line on a dyno pull, you're looking at filtering that's done on the raw data.

Ok,

So I race all the time (I beat a Ion Redline last night w00t w00t, we both chirped second but I got him in third gear).

I'm going to drop the big poncho...what's the best point to shift at in a GSL-SE (85) in a drag race?

Thanks,
Tech

Look at my first post in this thread.

This is from my 84 SE. The only mods are Rotary Engineering Header, Magnaflow exhaust and K&N Filter

139.6hp and 121.9ft-lbs at the wheels.

Steve

It looks like it's pretty easy to get more power out of an SE.

This is from Yaw's website. Purple lines are comparison of a stock ported and street ported 12A engines with a modded nikki in them. Notice the peak hp of the sp engine is at 7800 rpm. Interestingly enough, at low rpms the stockported engine makes more power.

The blue line is torque, and the red line is air fuel ratio.


http://www.yawpower.com/strtprt12.gif

I don't know how interesting that is. Improve flow volume and reduce flow velocity and you gain top end at the expense of low end. It's basically what happens with most porting.

What is interesting is that that shows the stock port engine at 150hp. Even on an engine dyno (which is what Yaw's got), that doesn't seem right.