txs Juan
tis strange isnt it--have you retighen your manifold--no air leaks --right?
you must have a differant tune than I---i never see 14 degrees of timing at 78% tps--i see 20.
you know you can speadsheet the ob2 data now? kinda cool.
I am looking for the blue injectors now--know anyone that has some for sale? Is there a compatable 480cc RC injector out there?
i dont like being at 100% duty cycle--especially on extended track runs.
DOnt need to retune just because of installing the blues--
I do wonder about your fuel pressure---hell i wonder about MY fuel pressure.
OD

 

Would someone mind posting a DIY for the fuel injector swap??

 

This was done this morning:

 

^^^Nice A/F ratio.

 

I'd like to see the TPS on that one, as the MAF looks kinda weird in the bottom end.

Cheers,
Hymee.

 

Is it consistent with letting off the throttle completely after I peaked? I did this on the way to work. I plugged the logger in right before that pull, which was done right as I turned onto the road leading to the parking lot at my job (I had to let off because I didn't want to drive past the lot).

I'll post it when I get home.

 

Yeah, that bit looks normal, I'm talking about the bottom end, in the first third/half of the run.

Cheers,
Hymee.

 

Here it is with the TPS:

 

cant do screen shot---dont ask --- but at 130mph , 7581 rpm and tps 78%---a/f was 11.7---curves are smooth
OD

 

The MAF and the TPS match up perfectly, thats what Hymee was asking about.

 

isnt there a slight delay between tps/maf and the a/f's also--thats normal --right?

Ok for all yall fuel starvation/cut problems folks. I have a low cost plan to fix this. With those of us concerned also about track a/f's--before you jump to the blues--address your fuel pressure.
Unfortunatly i am not aware of anyone that has monitored fuel pressure on an oem system while on the track--so we are in a way flying blind.
I am convinced it is not a fuel supply problem as this is occuring with a full tank!
The location of the fuel pump is not good for track and the insides of our tanks is baby butt smooth. We also have a dual speed/returnless/venturi balanced system and the pcm helps to regulate our fuel pressure by turning the fp off and on approx 18k times a sec! When you start messing with a system like this --be careful you dont make things worse.
1st---DO NOT convert to a return type system unless you want to spend both time and money getting it balanced out. Not an easy job.
2- external filter is mandatory for symtomatic cars (why some have this and some dont is still a mystery--maybe they aint fast enough--lol)--advise this to be a cannister type set up(so you dont have to clean it every week!) and a 10micron size filter. The filter IS impeding flow once it has been in use awhile---some areas obviously has cleaner gas than others. Pre mix DOES affect this--more sediment in your gas the more effect it will have on the filter. by the way--if you aint running at least 1/2oz a gal you aint doing nothing a symtomatic pump assembley is down on output approx 30% during its high speed mode.
2- the venturi line dumping spot in the fuel can has an exit both to outside the can and inside the can--stop the one going to the outside up with a good epoxy. this site is shared with the fuel pressure regulator bypass flow. DO NOT mess with the baffles inside the can--leave them alone. You can enlarge the inside diameter of the venturi line just a little if you like--but it doesnt make much difference --if you do be sure you do not go to far up. You can see were the diameter gets really small--dont mess with that.
3- the fuel lines in the fuel pump assembly itself can be improved to a slightly bigger size and a shorter lenght--eliminating as many bends as possible. Use the right type of fuel line to do this.
4- install 2 trapdoors one toward the front of the car and one toward the back of the car. There is not much room between the can and the pump assembly so keep that in mind. install approx 1/2 the way up the can NOT at the bottom--we aint racing and we dont care about using that last gallon of gas.
5- trim the little tabs off the inside of the fuel sock --the tabs that will snap like a button at the fuel pump pickup spot--when i took mine out it was snapped closed--this relieves a very small restriction--make sure the sock(small to start with) is fully expanded --thickness wise--on reinstall.
6- at this time it has not been identified that the pump itself need replacement.
6- you can install a jumper switch to run the pump in a constant "high" mode" FOR TRACK USE ONLY. Install the switch so as you are getting out of grid you can turn it on and as you are pitting you can turn it off. do not run the pump in high mode while the car is idling or in a low speed operation. Mine is on the console with a guard on it.
This is a little work but money wise it is around $100. I am using the aeromotive 10 micron cannister type fuel filter and you have to buy a couple adaptors/a little bit of stainless hose- so your oem fuel line will hook up to it
This will fix the fuel starvation issues that are being experieince at over 1/2 tank full. 1/4 tank and below---I dont know. I suspect more work will need to be done for that.
yukons--on over the holiday---thanks Juan and all for the info on that.
By the way I got that ignitor box man R8--appreciate that and i will be analizing that system to see what is what--i owe ya one.
Olddragger

 

Ouch that sounds painful.....

 

Ouch - Especially if it involves the discharge of the coil packs.

Cheers,
Hymee.

 

na no probs--just started having misfires --both rotors--had the mazsport ignition system--think igniter box is the problem but am not certain.--meanwhile the yukons go on.
i analyzed a little more on the fuel delivery system.
seems that at wot and with injectors at 100% duty cycle the car with the high power injector set up has roughly a 37cc per sec
fuel demand--if you add the blues then you have a little over 44 c/sec demand.
now our pump is rated at 255L/hr at 45psi---BUT we are at 58-60 PSI so the pumping is down--maybe to around 230L/hr? This is only in the high pumping mode. That means the pump is supplying (with no restrictions) approx 63 cc/sec.
So with engine use/demand as stated that means the fuel can is being supplied by the fuel pressure regulator bypass of only 26cc/sec--not a whole lot.
now in the low speed mode the pump is putting out maybe 150l/hr (with no restrictions). thats a total output of approx 41cc/sec from the pump. so to the can is whatever is being left over. and depending on the tps etc whatever is left over.
The can does not fill well or fast from the little supply valve at the bottom.
so at wot and 100% duty cycle there is not much margin in fuel supply IF the tank is not full enough to go over the cup lip--i have no way of factoring the venturi tube.
this is further suggestion we may really need a constant high speed pumping mode while on track.
I dont want to think about this anymore for a while
OD

 

Two bad we can't just connect both stock tanks with an AN12 line on the bottom and some AN 6 line on top.
Then put a "T" in the top and bottom line with a nice Aeroquip pump on the bottom line, and a return in the top T fitting.
Run a new half inch supply line and use the old factory line as the return.
Tap both fuel injector rails and T those to a pressure regulator.
/Did I miss anything?
//It would never work....

 

Well, im contemplating going air to air with the IC setup. Any thoughts?? I can go either way, air to air or water to air.

 

What are your goals with this new SC setup? Are you aware that if you simply spin the blower we have now an additional 1500 rpm it would make @14lbs of boost and still be @500 rpm shy of the manufacturers recommended redline??

I would much rather see Pettit package a new pulley setup, with the proper fuel injectors and flash, for the blower we currently have.

-Yambo

 

HAPPY THANKSGIVING to all the Pettit SC owners....

 

Happy TG, almost forgot.


As for the over spinning of the blower I think you measured the wrong spot on the pully. Get the inside groves of the pully. The reason im going with the 2.1 blower is I want to test it out. See, when we had the 1.4s we had to over spin it 9,000 RPM to make the 8 psi we had but in doing that it was so parasitic and the flow rate was so down that we only made 220, maybe 240HP to the ground. With the 1.7 your about 700 RPM short of redline. So if you take the 2.1 and run it at or around the same amount of boost and maybe make more power, we wont know till its done. If my thinking is correct from the R&D weve done. With the 2.1 tacked it just might make 400 HP with a properly built rennissis that can handle that amount of power and boost. Im starting with a 1 to 1 ratio, That leaves me 9,000 RPM till redline on the blower to play with. Gotta go step buy step. Im thinking im going to need a new fuel system.

 

These measurements were taken with a micrometer. Let me know if they're wrong.
4.7585 for the "crank" pulley and 3.2542 for the blower pulley. That brings the drive ratio to 1.46. That means we are spinning the blower 13140 rpm at redline, making @8-9lbs of boost(my boost guage reading).

Now I have personally spun the blower an additional 7-800 rpm using a "crank" pulley I "acquired". This produced an additional 3lbs of boost across the entire rev range, to include 9lbs at 3000 rpm all the way up to 11-12lbs @8000rpm. I couldn't go any higher as my fuel injectors could not keep up and I was experiencing some detonation due to not running any alky(That is no excuse, I know I should have installed the alky and larger fuel injectors first, but thats just me).

The point is that our blower size(1.7L) is more than capable of producing enough boost make all of us power-mongers happy. How hard would it be for you guys to test some different pulley combos along with different fuel injector packages for those of us that want more power and are willing to pay for it?? A lot easier than redesigning a system around not only a different size, but a different type of blower.

-Yambo

 

mork--no belt slippage?
i am interested in the 8K and BELOW curve.
no change in idle?

Moon on the a/a versus a/w--i prefer the a/w with the w/M injection. reason is the a/a takes up all the front of the grill--air dam area and it increases the work on the engines coolant system.
many reasons for one or the other--
OD

 

Of course there is belt slippage. The same way there is slippage now with the stock setup. If you're interested in the curve, take a look at our fellow owner who is producing MAF readings of 379g/s(although that is not optimal due to his stock ignition setup/lack of midpipe).

-Yambo

PS. Most of the things i've recently posted have been common knowledge(for some of us) for the past several months, if not longer. I'm just tired of trying to be diplomatic in the way I patiently wait for all of the "experts" around here to give me a product that I have been willing to pay for.

 

Well, the water air has kinda grown on me also, guess its time to relocate my battery again to make room for the hardware. Any thoughts on wether or not I should use 2 I/C cores.

 

Moon, with that monster S/C you may need three I/C cores.
I think we have the right idea for the short run, larger injectors and more spark.

What do you think is the best for sparking this baby off?

 

What size injectors would you guys recommend for the 350-400whp range??