i was just wasting time reading up on some fastest supercars list and noticed the saleen s7TT only uses 52lb injectors for 750hp. why do you guys need 60's??? even if you figure that youve got a 4 instead of an 8, 1/2 the hp from it would give you 375 from 52lb injectors so why do you guys need 60lb's when you are under 300hp??? or is there more to it since youde also have a 3.5l i-4 if you cut the saleen v8 in half?

 

Just beacause they are 60Lb... does not mean that the duty cycle goes to 100%

 

we have 1/2 the injectors (like you stated) and we have room to grow. You don't really want to run your injectors to the max too often.

 

The half horsepower thing doesn't really work. 4 cylinders turning one crank 2 cams etc...or 8 cylinders turning the same number.

Also remember, the blower isn't exactly the most efficient "compressor" in the world either. Lots of parastic loss and VE of both the blower and the engine takes a dive at high boost levels mainly because of heat.

 

ahhh!! i remember another thing. We have to fight manifold pressure, they don't flow as well at higher pressures. Gratned we run higher than rated fuel pressures, but if you have anything other than a stock pulley, your putting more pressure in the manifold, than our fuel system has over normal systems.

 

First off, the S7TT injectors are 42 lb/hr, not 52....http://saleen.com/saleen_s7_specs.htm

S7TT:
------------------------------------------
42 lb/hr x 8 injectors = 336 lb/hr

7.0L of air + (7.0L x 5 psi/ 14.7 psi) = 9.381L of chamber air (@ atm pressure)

336 / 9.381 = 35.817 lb/hr*L



Cobalt stage 2:
------------------------------------------
42 lb/hr x 4 injectors = 168 lb/hr

2.0L of air + (2.0L x 15 psi / 14.7 psi) = 4.041L of chamber air (@ atm pressure)

168 / 4.041 = 41.574 lb/hr*L



----------------------------------------------------------
Assuming linear increases from total chamber air and compression ratio...

Chamber air diff: (9.381 / 4.041) * 245 hp = 568.76 hp
Compression ratio diff: (11.0 / 9.5) * 568.76 hp = 658.56 hp

The rest likely comes from low intake temps, free-flowing intakes/exhausts, and strong engine internals. Notice that the Saleen dumps more fuel with the 42lb/hr injectors (i.e. with less boost) while ours are supposed to be maxed out. I think this has to do with manifold pressure and the fact that injector ratings are measured at atmospheric pressure, while ours fight the manifold pressure.

 

Anytime you want to help me with my Calc Home Work you let me know!

 

You completely through out the BCSF, which is basically the efficiency of the engine

 

man, NR your roaming 2 forums, what a PW...

...post post post, post the day away...

...supposedly, we can use the RX-7 turbo JDM (J engine?) type injectors, they have the same impedence and are 55#/hr. we'd just need a custom harness.

 

RLF, CSS, ECOforums, SaturnFans.. the 1st 2 I refresh about every 5 min the later about every 30 min. I get around!

It's easy to make a harness if you have a harness from each.

 

^yea...but why go through all the trouble when you can buy bigger inj's fo rthe same price...

 

lol, you're the one that brought it up! fool!

 

i dont think i would want a 60 pound injector, i mean the ones in my car only weigh like a few ounces. wouldnt want them to be as light as possible.. hehe .. now let me clibmb back into my time machine and i will right the wrongs once done..


just playin..

 

nuh uh!...Jason Smith brought it up...not me...WTF are you talking about?

 

i mean, you brought it up here.

 

Impressive young apprentice!

 

now we are comparing a saleen s7 to a cobalt and wondering why the injector size needs to be 60lbs/hr on the cobalt a smaller pulley.
i dont even want to try with this one. ppl make my brain hurt

 

Then don' try, we already explained

 

i was just kidding man

 

dont they normally try to keep duty cycles under 80%. i read about it somewhere but id rather pay someone else to worry about that isht. dont have to worry about that on my 65. i got the 52lb from supercars.net. suppose i couldve checked out saleens site instead. so if you switched to a turbo you could get more power out of the smaller injectors before having to bump them up id imagine?