Some of you may remember my previous attempt at a higher horsepower 13b, which was in 1976 Rx-4. 206rwhp was a bit of a journey, and I was pleased when we finally did it. Later, I decided to sell the Rx-4. We pulled that good ol' engine out, and dropped it into my GSL-SE daily driver. It was installed with a turbo II transmission at the same time. Before I installed it, I wanted to tear it down, and re-port the intake ports. We were trying a experimental version. After break-in, the engine made 180rwhp and 128rwtq! NOOO!! What happened? Was it the ports, or was it the chassis with more drag from the tranny? I still dont know. But it set me on a path to re-gain and beat the old 206rwhp from the Rx-4. After doing lots of exhaust tuning, and trying out all types of things, the goal was within reach. Then I pulled out the distributer and old-school haltech, installed a electromotive setup. After more tweaking, it finally hit the mark I was shooting for 216rwhp. Yes! Finally! A total of 36hp and 20ft-lbs gained over the begining. So thats the story. Here is the chart.


Almost forgot here are the specs-
13b-re 2 rotor cosmo engine
Our circuit port intake and exhaust
9.7:1 n/a rotors, dynamically balanced
4x 550cc injectors
Stock 13b-re intake
Electromotive Tec3R ecu
Electromotive inductive coils
Custom ignition wires
4x NGK trailing plugs
Our own custom header, merging to a 2.5" exhaust
Racing beat main pulley
S4 waterpump
Green 3" air filter

Tuning notes-
Air fuel ratio 13.0-13.5 through out
zero split from 2000-8600
Total advance with 89 octane 21 degrees
Total advance with 93 octane 29 degrees

 

Thats it eh...just like that haha

Com'on details man!!

Is this using stock S5 N/A rotors?

 

There you go added it to the first post, sorry about that! hah. The exhaust work was so extensive that I cant give all the details yet. But will sometime soon. I will say the primary runners are 2.0" o.d, stainless .065 wall. Merges into a series of 3 mufflers, and is 2.5". Its actually pretty quiet and a great daily driver.

 

Here is a overlay of a good running GLS-SE with a test pipe vs. my 13bre. Just to compare bottom end torque.

 

good stuff!

any pics?

 

Nicely done. Looking forward to reading those exhaust details.

 

long or short primary on your exhaust?

 

Do you plan on keeping the stock RE manifold?

 

Yes, I dont see any need to change it out to a ITB setup. I have been evaluating the current setup, and I think with a bit more tuning/changes to the exhaust, and taking a section out of the lower intake, that 223-230rwhp might be within reach.

 

How much timing (leading and split) did you end up with? Rx-8's are using about 30 degrees leading with 15 split from the factory.

 

Light weight flywheel?

 

flywheels have nothing to do with making horsepower.

 

I posted it below the dyno chart, under specs. Back in the day I usually ran about 27-30 degrees advance. But I've found as the VE gets higher, and further into the rpm band, dynamic compression gets really high. So with 89 octane now, I could not go past 21 degrees without pre-ignition. With the 93 octane total advance went up to 29 degrees. This was always with zero split. Zero split always made more torque than any other split.

 

Engine bay shots. I didnt clean it up at all, so its not much to look at. But it does do the job!

 

Technically, yes, but a flywheel absorbs energy to be accelerated up to speed along with the engine. The heavier the flywheel, the more energy is absorbed getting it up to speed, therefore if you lighten the wheel (or make it smaller in diameter), less energy is absorbed, and more gets through and makes its way to the wheels. Presto, more wheel horsepower with a lighter flywheel (works with lighter and also smaller diameter wheels, tires and brake rotors too).

 

I am running racing beat 13lb steel flywheel. Sorry I missed that earlier

 

I hate when people say lightweight flywheels don't make more HP. Ture they don't, but they free up hp that was being used to spin it and put it to the wheels. Like that RB exhaust you just put on your car didn't make any more new HP it just freed up the horse power that was being used to push the exhaust out of the stock exhaust, and now it's going to the wheels... Nothing makes more HP it's jsut re alocated somewhere or moved in the revreange. Every engine can only make so much torque and it is based soley on it's dispalcement, and volumetric efficiancy. How much power you make depends on where the engine makes it's peak tq and when it's VE is most efficiant.

Nice header! Nice and straight off the block before it turns!

 

That's not exactly true, while a bad exhaust won't let the car produce the maximum possible power, it doesn't work in the way as you describe. In that case the engine is actually making less horsepower.

 

FAIL!

Show me two dyno sheets where the only variable changed is the flywheel from stock to a lightened one with the same engine. They will not show an increase in horsepower. If you were to do the same dyno with the only variable changed was exhaust, from stock to an open free flowing exhaust you will see a horseopower increase on the dyno. So you are wrong in your statement above.


FLYWHEELS: The actual horsepower of the engine does not change related to the weight of the flywheel. However, to increase the engine RPM, and accelerate the car, all rotating weight (as well as the entire car) must be speeded up. This requires power, and the heavier the part, the more power needed to speed it up. The less power needed to speed up the flywheel (and rotors, clutch, driveshaft, wheels, tires, car, etc.) the more power available to speed up everything else. The question we are asked frequently - "How much more horsepower will my engine have with a light flywheel" - is not the right question, because the answer is NONE. What you will have is more available horsepower to accelerate the car and yourself down the road.
This is straight from Mazdatrix=-

 

No the engine won't make more hosepower, but in the real world, you'll see more hosepower getting to the wheels on acceleration. It's fairly simple physics, it takes energy to accelerate a rotating mass up to speed, how fast you do this is power. If you reduce the weight, thereby reducing the inertia, it will take less energy to accelerate the mass, so therefore it'll take less power to accelerate the mass up to speed. This means that you have to exert less power to accelerate the flywheel and more power getting through to the wheels, where it can be put to good use accelerating the car.

This only holds true for acceleration, so if the dyno measures power at set, static rpm points, then there's no acceleration and it won't show a difference, but if you were on something like a dynojet, you'd definetely see a difference, and the lower the gear, the faster the acceleration, the more you'll feel it. So it'll help you accelerate faster, but it won't help you acheive a higher top speed.

A good explanation here: http://www.uucmotorwerks.com/CTSV/LFWCTSV.htm

Dyno results: http://www.g35driver.com/forums/revi...lywheel-2.html

 

Ah, but was GtoRx7 doing his dyno pulls accelerating or in steady state mode?

A flywheel may show a gain in acceleration mode, but never in steady state mode.


Anyway, I want one of your headers. Or maybe not - I'm really more concerned with getting some power up in the 3k-5k range, flatten the powerband a bit. High HP is useless if it takes you most of the straight to get to that point... by then the competition has passed you already. In the racing series I will be in next year, midrange torque will be essential, because 1st gear will be useless but 2nd gear ain't enough.

If nothing else, I'll have to go with a turbo... attached to a Ford 4-cylinder... funny how our priorities change when there's money on the line!

 

Good article comparing dynos from Sport Compact Car Magazine: http://s-cars.org/postnuke/downloads...sdynoAug04.pdf

 

The header actually gained a decent amount of bottom end and top end. It seems that a good exhaust gains more power everywhere, and a poor one will take it all away. The dyna pack is a steady state. If you type in a 14 sec pull, it will take 14 sec regardless if its 200hp or 900hp.

 

If it does a XX second pull from low revs to redline, then it's not steady state. Steady state is it holding the engine at a set rpm point.

 

Total power output of the engine doesn't change, but driveline loss decreases, so there is a net gain in power.