Yeah, I checked out the boost flow website, it's good to hear a reputable place branching out.

And yeah, I'll keep waiting on him then, I'm not in a huge rush anyway.

 

First update, first batch of parts came in:

 

i wouldn't be too sure the "stock" intake he's using is holding him back, and he's using the 9.7's.

 

Yeah, the modified 13B-RE intake is pretty nice, and if he's on 9.7's... whew. Um. Not quite sure what more I could get. I guess then my new goal would be 230whp. That'd still be good. I'll have to research more.

 

250rwhp can happen from a non turbo 13B but you are not going to do it. See the car below. That is a full blown race 13B using 10:1 RX-8 rotors and a bull blown race bridge port and a full blown race exhaust system that is likely 110+dB and uses megaphones where you use mufflers

Keep on dreamin'

 

Just remember the Mazda R26B only made 687BHP @ 9000RPM with a tuned length intake, tuned length exhaust and no mufflers. The R26B also had slide throttles so that on WOT there is literally NO OBSTRUCTION whatsoever in the intake path.

Halve that (to get it into the ballpark of a 13B) and then put it through a 83% efficient driveline. 285rwhp from the best non turbo peripheral port rotary motor anyone has ever made PERIOD.

FYI specific fuel consumption of R26B

.473lb/bhp.hr @6000rpm / 487bhp
.513lb/bhp.hr @9000rpm / 687bhp

 

Uh huh. 230whp can be done on a streetport, low money build. 250whp isn't that hard if you get any kind of bridge. I've done enough research to know what I'm doing, go frighten some noobs.

 

In Australia 200rwhp is into the 12s in a gen1. Watched my mate do it last year Another guy I met did 10.9 in a gen1 on slicks with only 290rwhp.

 

Uh huh. My last turbo Miata was well into the 12's with 250whp.

My only experience with the first gen is autocrossing a GSL-SE, honestly.

Owned an FC for a while, last time I was planning to do this swap, before life got in the way.

I know how fast is fast.

 

Have a read and start comparing your kit to something like this with 5 years development behind it. http://61.68.253.185:8080/about.html

 

Read it. I quote:

"IPRA compliant bridge porting"

Without knowing the template on that, it's hard to say. Many classes use restrictor plates or restricted sized openings to limit maximum horsepower. May cars will make 1.5x their restricted HP if they're 'uncorked', if they're very highly developed.

If you could give me more information on what that porting consists of, I could get some real meaning from that link.

 

No restrictor plate. There is a limit on the how far into the rotor housing the housing part of the bridge port can go. Ie you can't hog it out until its basically a side fed peripheral port.

 

Yeah, I was comparing the port restrictions to a restrictor plate, more than I was saying there was one there. You know, pretty much the same concept?

What's the limit to how far it can be 'hogged out?' I went to the IPRA site and couldn't find a rulebook on it.

 

Jobro,

You got to remember most US guys talk in dynojet numbers which are roughly 15% higher then standard dyno dynamics numbers..

 

I've made up to 240whp SAE corrected on a dyno jet, and my ports are small (primaries, secondaries, & bridge). I'm guessing more porting would net 20-30whp, without going J or D bridge.

I'm guessing 230-235whp is close to best case scenario with a monster street port. I was just skeptical on 250whp.

 

I fully admit I might not make that number. If I don't, I don't. It'll still be a very fun car no matter if I make 230 or 250. It's just a goal, and I do aim high. I like to optimize things.

 

I agree aim high and be proud of achieving your goal.

On the dynos I use it would land around 160-180rwhp. You guys would all call that 230. The problem is when you take another test into it like the quarter mile into it. Then the figures I use match up with Hale and his derived terminal speed equation.

I never dynoed by gen1 in its trim that it was in for about 15 months. Regardless I have a hand full of slips. Once it was sorted it was reliably going 109mph in full street weight (even weighing it down with unnecessary fuel). Stripped and less fuel it was doing 112mph. I weighed it loaded and it was 2552lb's. I decided to call the stripped trim 2475lb's now. All my numbers line up. A mate with an s2 (similar setup to my 15month one) has a mainline sheet for 200rwhp (from a credible dyno) and has ran 12.80@106 with highway gearing and normal road tyres. I've since done a shitload of work and its in no way ready to race. Regardless my new sheet shows 1400lb tractive effort 331rwhp. I've since changed the gearing and tractive effort should now read about 1145lb with the same power. I've geared it for 128mph in 4th gear because I'm going to make it happen (with no new equipment)

Anyway start using the most accurate and repeatable methods for determining things like this and it will come to you that nearly no testing is needed if you design accordingly.

Repeatable figures by factoring:

Max Duty Cycle:= 85%
Specific Fuel Consumption:= .55lb/hp.hour
Power at Crank:= 220BHP (never tested)
Power at Wheels:=180rwhp
VE:=115 to 130 (expect low side)
RPM Ceiling:= You know that around 8000RPM for S5NA rotors but you REALLY need to port accordingly. Factory port close is 80ATDC so it is basically proven you need a VERY TALL port to make power at those sort of RPM's.

Now you will size your injectors correctly.

 

For what it is worth, I had my car on Logan's dyno (forgot the name, electric device that bolts to the hubs) when it was a street port, and it made something like 150 whp. A few months later it was on a Dynojet and put down 170whp. Injector duty cycle/size calculations and weight/trap speed calcuations both pegged the engine at 200 crank horsepower.

I can't see that as "reading high", seems right around correct if you ask me.

 

How on earth can a dyno that reads power through an 2 additional lossy interfaces read more wheel horsepower. By obvious logic more power will be reaching the hub than the wheels.

They are reading wheel horse power and doing something to the reading. That is no longer a raw reading and has been adulterated.

Your numbers do not scientifically make any sense.

 

I don't have answers, just a few points of data.

It should be noted that Dynojets don't measure power, they measure acceleration of a known mass and thus infer power.

The hub-mount takes a direct measurement. I am unfamiliar with the devices, so I can't say for certain whether it calculates power based on the current required to hold the engine at a set RPM, or if it has an internal load cell to measure torque directly. Certainly I'd hope it uses a load cell as this is far more consistent and reliable.

Both dynos can be "cheated". I had a 9 pound flywheel in my car, and the Dynojet runs were made in 3rd gear because of driveline angle issues that weren't fully sorted at the time. I didn't want to know what the driveshaft would do to the transmission and rear if it was spun up over 6000rpm. So, did this hurt power because of transmission losses, or did it help power because the engine can spin up faster?

As for the brake dyno, all I will say is that you should always look at the test method on the chart. Playing on an engine dyno (Land & Sea), I could make a 550 ft-lb V8 make over 600ft-lb by changing whether I allowed the engine RPM to go up, or if I loaded the RPM down from a higher speed...

Heh, that reminds me. Our Land & Sea is set up to mimic the installation of a standard GM transmission. I really must get my *** in gear and finish my rotary to GM transmission adapter so I can load an engine on the dyno and play around with certain things before we sell it. Engine dynos are nice to have for some things, but chassis dynos are more versatile when the big picture is taken into account.

 

My understanding was there was a set acceleration allowed by the rollers (measured in KPH per second) and power in addition to this would be dumped into a load cell. I would love to know the maths involved with how they actually work and then in turn the calibration procedure.

170rwhp comes back to 205 engine horsepower and is about right. Like I said The Mazda Lemans team are did 343 engine horsepower from pair of 13B rotors Competitive Bridgeport 13B's are doing approx 300 engine horsepower (honest chassi dyno reading 250rwhp) The 2 above examples are race bred motors with no exhaust systems.

Street 13B's should be looking at around (UNDER 220 engine horsepower) and displaying 180rwhp on an honest chassi dyno.

I went to the 1/4 mile strip a few weeks back. I watched a non turbo inline6 4L stage and run (think 3600+lb's sub 6000rpm NA 4L). Saw it do 12.?? @ 1??mph. To be honest I was taken back. I watched this guy drive that car into the facility. Not obscenely loud. Street legal drag racing tyres. I was very impressed. Talked about this to 2 guys in that make of cars scene. Well that car uses nitrous. That explained for where this performance I could not logically justify came from.

 

Yeah, I keep getting asked "So when you going to put a piston engine in it?" Something about making more power without all the noise, and you can fix a lot of malfunctions short of engine overhaul without having to pull the engine.

Only problem is finding a piston engine that makes no more than about 170-180 ft-lb of torque while still being able to meet my power goals and inexpensive. Until then, I just have to live with driving my a car one weekend, then waiting three months to drive it again because I never have time to put it back together Too many people want their 3800lb street luxobarges running 10s or better for me to have time to work on my own stuff.

 

we've done back to back runs with different cars in different gears, and its car dependent.
on NA cars it basically makes no difference (1-2hp)

on turbo cars though, you're balancing more load in 4th, with a longer run time. so in 4th it might spool up quicker, but it also can heat soak.

we've done a bunch of NA cars, the funniest one was my 1971 Mercedes 300SEL 3.5, 3rd vs 4th (automatic) made less difference than pulling the air cleaner lid. pulling the air cleaner lid off actually lost 4hp!

the turbo car was a 13B cosmo FC, with a hybrid turbo. 3rd vs 4th didn't make much difference on that car, but the shape of the hp curve does change slightly.

so its a factor, and you can't say its going to be the same for every car, but its really only important when you're trying to compare different cars anyways

 

Why are you limiting yourself to 170-180ft lbs of torque? Is that the limit for the road surface?

 

He races on dirt. It's a very poor road surface.