Which inj.-55's or 72's?
- Thread starter turbosam6
- Start date
Welcome!
By registering with us, you'll be able to discuss, share and private message with other members of our community.
Richard Inglett
Member
- Joined
- Jan 22, 2002
- Messages
- 83
There is a less expensive alternative to an intake double pump setup. Now don't laugh but before intank double pump setups were available, external pumps did OK. A Bosch GFP 204 pump in series with your 340 pump might be the answer for safely running 10.90's. Estimated cost is less than $200 but then you still need different injectors (72/75's sounds like a good choice) and updated programming. Might as well save a go for the double pump setup.
What you may find is that you can get by with a single 340 and 72's where you may need a double pumper for 55's to go the same speed. Here's why.
If you look at the flow charts for a 340 it really drops flow at about 70 PSI. With everything else constant and say 25 PSI boost to keep from leaning out with 50's or 55's you may need to start with a static pressure of 50 PSI or more. When you add 25 PSI boost to that, you need to maintain flow at 75+ PSI which a single 340 can't handle depending on how fast you are going and how much fuel you are using.
Now with 72's you will need less pressure to supply same amount of fuel. SO you can start with a pressure of 40 PSI and add 25 to that and you may be able to maintain flow @ 65 PSI. You will need to monitor this closely as you will still be close to the limit.
A double pumper will be in the future if you plan on running any faster than a very high ten .
HTH
Sully
If you look at the flow charts for a 340 it really drops flow at about 70 PSI. With everything else constant and say 25 PSI boost to keep from leaning out with 50's or 55's you may need to start with a static pressure of 50 PSI or more. When you add 25 PSI boost to that, you need to maintain flow at 75+ PSI which a single 340 can't handle depending on how fast you are going and how much fuel you are using.
Now with 72's you will need less pressure to supply same amount of fuel. SO you can start with a pressure of 40 PSI and add 25 to that and you may be able to maintain flow @ 65 PSI. You will need to monitor this closely as you will still be close to the limit.
A double pumper will be in the future if you plan on running any faster than a very high ten .
HTH
Sully
I am running stock ECM right now. I want to go to speedpro(fast) when I save up 2 grand. I use Red's chips although I do tweak them for my car. I also have a Bin from Jay Carter I am gonna give a try soon. Once again I will tweak it for my car.
Sully
Sully
I just upgraded from the MSD 50s to the 72s with a 3.5 MAF, Trans + and Extender Extreme, my blms at idle are a bit rich, 95-105 most of the time with 45 PSI FP.
bob mentioned that the open loop performance is better, but I haven't tried it yet. only difference I saw is that the mileage seemed to get a bit worse but performance and streetability are quite good.
but unless you have a big turbo/heads/good flowing exh ext.... injectors this big probably just aren't needed.
you need to match the CFM ratings of all the above to see if you can flow enough air to need that much fuel.
my car was leaning out with the MSD 50s and I wanted to provide some "safety margin".
I think the 72s work just fine on the street and may work even better with open loop. I'll keep you posted.
another thing to consider is that by the time you get the big MAF trans + and chip, the Maxeffort is a better deal. I haven't tried one yet but am considering it. both seem to work very well but I believe the ME might be better with the big injectors due to the additional tuning options.
any thoughts???
bob mentioned that the open loop performance is better, but I haven't tried it yet. only difference I saw is that the mileage seemed to get a bit worse but performance and streetability are quite good.
but unless you have a big turbo/heads/good flowing exh ext.... injectors this big probably just aren't needed.
you need to match the CFM ratings of all the above to see if you can flow enough air to need that much fuel.
my car was leaning out with the MSD 50s and I wanted to provide some "safety margin".
I think the 72s work just fine on the street and may work even better with open loop. I'll keep you posted.
another thing to consider is that by the time you get the big MAF trans + and chip, the Maxeffort is a better deal. I haven't tried one yet but am considering it. both seem to work very well but I believe the ME might be better with the big injectors due to the additional tuning options.
any thoughts???
I thought so too, I will try 40, I guess the recommended 45 pressure is for racing. bob b. really is great to work with and has been patient with my questions.
leaning out the idle should help a bit. I was very pleasantly surprised at the street manners of the 72s.
mid range torque is awesome and the top end charge feels great.
the combination is finally coming together. I do get LOTS of compressor surge shifting into 4th under boost or when I let off the throttle. air is backing up through the MAF and the car "shudders" pretty bad. guess it's time for a blow off valve.
didn't seem to be as bad before the 3.5 MAF. guess the car is flowing lots more air now which makes the problem surface.
thanks!!!
leaning out the idle should help a bit. I was very pleasantly surprised at the street manners of the 72s.
mid range torque is awesome and the top end charge feels great.
the combination is finally coming together. I do get LOTS of compressor surge shifting into 4th under boost or when I let off the throttle. air is backing up through the MAF and the car "shudders" pretty bad. guess it's time for a blow off valve.
didn't seem to be as bad before the 3.5 MAF. guess the car is flowing lots more air now which makes the problem surface.
thanks!!!
I am still waiting on the DS feedback on that 72 lb Extreme. Leaning
the idle out is not a problem and will smooth out any tip in hesitation you might have as well.
Feel free to play with fuel pressure to center the BLM's.
The 3.5" MAF flows a lot of air.
Bob
the idle out is not a problem and will smooth out any tip in hesitation you might have as well.
Feel free to play with fuel pressure to center the BLM's.
The 3.5" MAF flows a lot of air.
Bob
Hey bob!!! good to hear from you. I haven't gotten Direct Scan yet and it may be a while. car runs great with the extreme!!!
sorry but my $$$ are pretty low and I'm buying a car for my wife before any more toys.
it will probably be spring time before I get the Direct Scan going.
thanks for all the help, the Extreme is just that, makes the 72s run really well.
sorry but my $$$ are pretty low and I'm buying a car for my wife before any more toys.
it will probably be spring time before I get the Direct Scan going.
thanks for all the help, the Extreme is just that, makes the 72s run really well.
INPUT
I had to jump back in on this because. Have had practical experience. and was given a ride in one situation.
First an external pump though it pulls rather than pushes is fine
I think using a 340 pump. Not trying to create a war. But ran one
with stock pump, and a 49. Problem Injecters,where too small.
Which brings me to part 2.
I was in a car with a felpro. And unless you either have some one with you who knows. 72's can stall you out in traffic. It does take tuning. However just 4 weeks ago I was in a car with 72's and a Max effort 16 position chip. Smooth I actually drove it.
Point is sounds like you do need to go bigger with injecters. Choice will ultimately be yours. Just trying like everyone else to help the best
we know. This was not intended to sway or choose for you.
You got very lucky with the guys who gave you input.....Great stuff guys! Good luck would like to know what you go with...Sorry for long note.
HTH'ED
I had to jump back in on this because. Have had practical experience. and was given a ride in one situation.
First an external pump though it pulls rather than pushes is fine
I think using a 340 pump. Not trying to create a war. But ran one
with stock pump, and a 49. Problem Injecters,where too small.
Which brings me to part 2.
I was in a car with a felpro. And unless you either have some one with you who knows. 72's can stall you out in traffic. It does take tuning. However just 4 weeks ago I was in a car with 72's and a Max effort 16 position chip. Smooth I actually drove it.
Point is sounds like you do need to go bigger with injecters. Choice will ultimately be yours. Just trying like everyone else to help the best
we know. This was not intended to sway or choose for you.
You got very lucky with the guys who gave you input.....Great stuff guys! Good luck would like to know what you go with...Sorry for long note.
HTH'ED
Well, now its gonna be awhile, my car had a confrontation with a fence and a tree. Not good. I didn't do it, but the person who did is being very cool and paying for it. I'm planning on getting the 65's, once Scott (zam70) gets done making my car pretty again. BTW, thanks Scott, for getting on this so quick, I know it will look even better than before! Man, they weren't kidding about those fiberglass bumpers not taking an impact! Oh well, it will be cool soon. Thanks for all the advice, who all is running 65's? I think thats a good all around size for the car.
Intercooler
New Member
- Joined
- May 24, 2001
- Messages
- 3,534
I don't know many that are probably because they are "newer" so you can give us the details. I think you will be very happy!
