Lemming

Today was dyno day, using a Mustang dyno.

Numbers. 268 rwhp and 257 ft lbs of torque. Boost ran nicely up to 4.5 lbs. Here's the interesting part, we had to abort the runs at around 5500 rpms because the car was starting to do lean. I've got to find more fuel, I want to see where the HP numbers go as the hp increase is very linear from 3300 to 5500 rpms.

I should mention that I ran on this dyno back in March or April on the same engine. I can't find my sheet, but IIRC, my numbers were 210 rwhp and 186 tq.

I'll try to scan the dyno and post asap. Below is a video of one of the pulls (4th gear).

http://www.vimeo.com/15469482

Note: I corrected the rwhp and Tq numbers from my original post of 200 and 190 for my last NA dyno pull.

RajDatta

Wow, those are impressive gains. I wonder how much of that can be attributed to the intercooler.
Raj

Miles968

I love watching these projects come to life! Congrats!

Lemming

Crappy photo of the dyno sheet

edz968s

Good figures. Did you try adjusting the FMU to add more fuel?
Perhaps the lager injector would be a way to go, though mine have never worked, but then I have only been able to achieve 230 rwhp, so I don`t know if the fuel will strart leaning out higher up the rev range, though with the turn buckle fitted and a tighter belt, at the red line my a/f gauge shows rich

Lemming

I had the FMU closed completely and the raising rate as high as possible. On the final run we clamped the return line at the tank and still could not get enough fuel. I'm thinking of getting an 044 Bosch pump. A am running the new Bosch injectors, not the stock 968 ones.

Just to check a few things, I will determine the voltage drop to the pump today, just in case I did a bad job with my wiring, but I doubt that is the case. I also have a friend coming over on Sunday with a fuel pressure gauge to test the system.

We did monitor boost pressure and got to 4.6 at 5500 rpms. If it remains linear up to 6500, we should be easily over 5 lbs of boost. (green line on dyno above). Boost was being measured from the base of the intake manifold using the same line that goes to the FMU.

odurandina

at that point would you be able to increase pressure at the blower by couple of pounds after getting more fuel ?

Lemming

The pressure should continue to increase with increasing RPM (notice the linearity of the green line). Unfortunately, the printout that I have does not have a pressure scale, otherwise I could interpolate.

Carl Fausett

Dont confuse boost psi with supercharger output. A common mistake.

Boost pressure is a function of engine restriction, not supercharger output. The higher the restriction in the engine, the higher the back-pressure, which is measured at the boost gauge as psi.

What this means is his engine and induction system is breathing very well, and air flow is good.
Conversely, I get calls from guys with Hondas bragging they are running "20 pounds of boost" and proud of it. That just shows how choked off their engines are, and if they knew what they were talking about, they would be embarrassed to mention it.

Good job, Tim. Very well done. You now have more air than fuel - a nice place to be Easilly corrected.

As we discussed, get some larger injectors in there first, and then a tuneable Engine Management System. I favor the Electromotive TecGT system ( I also am a dealer for them). Then you will have absolute control over your injector phasing and all ignition and fuel events.

Jfrahm

Yes, boost is in many ways a measure of how much air your engine *isn't* flowing. You need to think in terms of the amount of air molecules that are actually in the chamber, not the psi of air in the plenum that can't go anywhere. And likewise psi is not as meaningful without taking the temperature into consideration. That's why you can make more power with a bigger turbo at lower psi than some people can with a smaller one just pushing a mass of hotter, less dense air at higher psi.

Lemming

Working on the fix, will have more fuel soon and will put it on the dyno again and report back, likely next week.

In the meantime, I'm still heading to the track on Wed. This is really just a shakedown of the car so I'll be short shifting and making sure that nothing falls off!

Lemming

Carl, we briefly discussed exhaust systems on the phone and you suggested as open as possible. They dyno was done with an open 2.5" exhaust. Do you think there is anything to gain by going larger diameter on the pipe?

Carl Fausett

There is such a thing as "too large" where exhaust is concerned. As the pipe gets larger, the velocity of the air going through it gets less. We like a certain velocity in the exhaust system to provide some cylinder scavanging action....

Because of this, generally speaking, as exhausts get bigger the bottom-end and mid-range suffer losses and the top end sees the gain. As a road racer myself, I value mid-range more than top-end, so I would say "no" and leave it alone.

There may be some improvement to be had from a single 2.5" to a single 2.75", but my guess would be that at about 3.0" the returns would diminish and you would do more harm than good.

odurandina

that diameter pipe is obviously, perfect.





the guys running the biggest turbo systems run 3" pipe. on paper this is even too big.


they should be running 2.75" pipe. but that's on paper.



my car hauls freaking *** and i haven't even added boost yet.

edz968s

I`m still down on power compared to Tim.
I have an a/c compressor coming in the pipe line to sort thr tension issue.
My fuel/air is ok at the red-line without an i/c and on stock injectors, it just that it won`t run even at idle with the larger injectors fitted, to rich.
I have another track day on 26 October which is a faster, longer track than the previous outing, so maybe I will run into heat or lean fuel issues, we`ll see.