Ok,
I hope I haven't p@#$ed off too many people who have crossfires by my earlier post about converting to carb. After deliberation, flaming, and research this is the current plan for my engine (these are the components I already have):

383, forged crank, hyper-pistons
Ported 624 heads, 2.02/1.60 stainless valves, screw-in studs, guides, and all the goodies.
Cam - Adv. Duration 290/300 Int/Exh, Duration @ .050 224/234 Int/Exh, Lift .465/.488 Int/Exh, 112 Deg. LSA
Offy crossram w/ custom top plate, modded wiper motor originally on JoBy's car.
2.xx" TBs, 90lb Injectors, front TB flipped, custom air box, also from JoBy.
7747 ECM

I got a great deal on JoBy's old stuff from member Cherry84. Now, I have a number of questions yet unanswered. I am curious some crossfire owners' thoughts on the setup, and the possible hp and tq figures. I also have a lot of questions about tuning. The 7747 I got supposedly has a HAM in it. There is a circuit board that has been soldered into it and there is a serial plug with I believe 7 wires. What exactly does a HAM do? Also, what is the EBL I've been hearing about? I am planning to use Ostrich and TunerProRT to do the tune, and apparently I can use the HAM with WinALDL for readings on things. What will WinALDL through HAM give me? Any comments on those components? And finally, I have been hearing about a variable fuel pressure regulator. I've done some searching on it. Are the FPRs with a "boost" fitting the same as the ones with a "vacuum" fitting? Anyone know of one that is adjustable for the range of 15-25 psi? Many of the ones I found were 0-10 or 20+. Thanks in advance guys.

 

Regards to the FPR- Mallory makes one 4-25 psi, thats what I have. You will need to bypass your current regulator. You can get it through summit or jegs. About $90

 

Is that one of the FPRs that changes based on manifold vacuum? I have heard from other people tuning with large intake crossfire systems that the fuel pressure required for WOT will run too rich at idle with the 90lb injectors no matter how short the ECM tries to make the pulse. What is the P/N for that Mallory FPR?

Also, how do I bypass the original FPR since it is in one of the TBs?

 

So, I've been reading posts on crossfire forum, and it seems that most forum members can't get a VAFPR to work because it changes the fuel pressure too erratically during sudden accel or decel. I understand that with EBL it is possible to compensate for that, but it seems very complicated. I think that for this first build-up I may be best off going with a constant fuel pressure and tuning the engine as best I can with that.

BTW, I measured my bored TBs and they come in at 2.13". Coupled with the 90lb injectors I hope this isn't going to overfuel my 383.

Dominic- I understand that you are having success with a VAFPR and EBL. Mind giving your thoughts on my build? The EBL is pretty expensive and it sounds a little hard to operate for a new tuner.

 

for the price of those 624 heads,DART 180cc heads would out flow them and have a better combustion chamber design. I'd ditch them if you haven't ported them already. TFS heads are only 1000.00 and a good port job,studs,valves etc is probobly around $800 minimum. If its any cheaper than that for the head work,I'd question the porters work and reputation if its cheap.

Thats a big cam for a crossfire and even the 7747

 

 

To get around the stability with the large injectors, and improve airflow, use four throttle bodies! ?

 

MAA-4307M FPR that I have. Pat at X-ram sent me a filler piece for the regulator that was on the TB, I removed that and put this in place of it. I also use a A/F gauge. Put the FPR on the return line.

 

qws
Are you using the "vacuum reference" port or are you just setting it at one fuel pressure and tuning the injector pulses a lot?

 

J,

I use the Aeromotive 13301 VAFPR. My vacuum port is hooked to the manifold. In order to achieve a reasonable DC% for the injectors at WOT, I need to run 20psi FP for my 350 motor. With A LOT of tuning, I was able to have the motor idle well and perform well overall. However, decel and trailing throttle would cause a stutter in the motor because the PW was just too short. Using a Variable Fuel Pressure eliminates that problem because the FP is adjusted up or down depending on engine load. The PW is in an optimum range regardless of rpm/kPa.
This can't be done using just a 7747, because the software must accomodate a variable BPC (Base Pulse Constant) depending on Engine Vacuum. EBL has that functionality. So depending on engine vacuum, the ECM sees a different size injector and properly controls fuel. The result is a much crisper throttle response. Last weekend I went to the track to compare the EBL calibration to the previous 7747 I used.
I actually ran a slower time with EBL, but my trap speed went up by almost 3mph. No question the motor was making more power at the top
because this time I needed to shift into 4th well before the traps. Didn't need 4th with the 7747. I ran slower because of the extra shift and because my 60' was slower due to traction. As for the cost of EBL, any time I can spend 225 bucks and pick up 30hp at the rear wheels, that's a pretty good investment in my book.

 

So, in order to get the Offy to run properly I'm going to need an EBL? How hard is this going to be for me to tune? This car is going to be a summertime DD, so I want it to idle well as well as open up. Realistically, should I just use a fixed FP for now and upgrade later, or will I be able to tune in this motor relatively quickly with an EBL? Also, when you were using a fixed FP, did you experience any idle problems with 20 psi, or was it just the stutter during decel? Also, both the Aeromotive and Mallory FPRs you guys suggested say "Return" style regulators. I thought I need a "Bypass" style regulator.

BTW, Dominic, are you using parallel plumbed TBs? If so, do you have a pic or diagram of how they are plumbed?

 

I have not ventured to far into the tuning of my xfire. I however have asked many questions and learned a lot from CF and xfire forum. When i rebuilt my motor, i swayed inbetween cams that would compliment my current setup. A stock ecm was where i planned to stay for a while. I ended up getting the Comp Cam 268h Energy Cam. Specs were as follows

CAM SPECIFICATIONS:

Basic Operating RPM Range: 1,600-5,800 RPM
Intake Duration at 050 inch Lift: 224
Exhaust Duration at 050 inch Lift: 230
Duration at 050 inch Lift: 224 int./230 exh.
Advertised Intake Duration: 268
Advertised Exhaust Duration: 280
Advertised Duration: 268 int./280 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.477
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.480
Valve Lift with Factory Rocker Arm Ratio: 0.477 int./0.480 exh. lift
Lobe Separation (degrees): 114
Intake Valve Lash (in): 0.000
Exhaust Valve Lash (in): 0.000
Grind Number: CS XE268H-14
Computer Controlled: No
Lifter Style: Hydraulic flat tappet

I gathered my info and decided on this because it seemed manageable for my car to run effiecently. The biggest thing I have read and seen with local friends is that the stock cam has a 115lsa. I did not want to deviate from that number to much knowing the issues they all have had with tuning their car.

My end result has yet to be tested at the track, but im guessing a mid to high 13 in the 1/4.

I have no had much luck with 110lsa and 7747 ecms. Such bad luck that the project was scrapped and sold as parts. I still own a 7747 for further testing on my vette.

 

What are you doing for your intake?

 

J = You should not have any problems idling at 20psi. It really depends on how much vacuum you will be pulling and what the map sensor sees. I am running 21lbs static pressure with 90# injectors with no issues. Your cam is much bigger than mine but I dont think it will be a problem. My recommendation would be to get the basic tune setup and then start tweaking from there.

Dom is right you cant go wrong with the EBL. I wish I could spend more time with mine to get the tune completed.

 

I still have a stock manifold on car. Stock TB's. I know someone with a ported manifold and tb's for sale. I might purchase those to play with - but only if I know for certain I can maintain the driveability i have now.

 

Elkabong,
Would your BIN be a good starting place for my motor? I'm just not sure what to start out with that will atleast run. Also, I'm debating between Ostrich and Prominator. I think I'm leaning towards Prominator at the moment, but what do others have to say about either?