83# 0r 96?

[Larry]

I currently have 83# injectors. I was running 650 Hp stk block- 68% duty cycle. I will be running 273 motor, 850 Hp. I will be driving on the road 100 miles a year or less. I had a 72 P trim turbo- I will be putting in a 76 GTQ with Reds Double XP pump (yep- I've seen the post, Iwill run with a full tank). Would you move up to 96 # injectors? Thanks Larry

 

[86brick]

When you turn the wick up with that combo 83lb injectors will be marginal at best (you'll definitely be over 80% duty cycle especially if your car is full weight) so 96lb injectors would be a good idea...... I'm sure guys with a similar combo and making about the same power (in the 850hp range) would agree with me that it's better to have a little more injector

 

[Intercooler]

Your thread has been edited

 

[BigChinooks]

I think you will be fine with those injectors,i run the same turbo on a 231ci motor with 72lb inj's at 30 psi and a double pumper with dfi and have had no problems.

Mike.

 

[86brick]

Larry, if I were you I'd call PTE and ask Pat or Joe how much injector you need for a 76 GTQ turbo w/ a 273ci motor trying to make 850hp (I'd bet when you turn the wick up all the way you should be closer to 900hp or more with your motor and that turbo)........

 

[Larry]

Mike = thanks for the thoughts. How fast you running?
Bodhi- the body of my car is not set up for that much torque at this time. Even 9.5 is gonna be interesting- if I get there. Larry

 

[BigChinooks]

My car runs 130mph in the 1/4 so far and am looking for 1-3 more mph with some changes and more tuning.

 

[Larry]

Thanks Mike

 

[Chuck Leeper]

Simple math

Here's the math needed to figure the injector size vs the HP..

Estimated HP X BSFC
________________ = Inj size in #/hr

# of inj's X duty cycle

Bsfc = Brake specific fuel consumption. [#'s of fuel per HP, per hour]
A general value is .45 to .50 for N/A engines.. Depending on efficiency of the engine...
A value of .60 to .62 is used for forced induction engines.
A duty cycle can be from 80 to 100%... 85% is pretty common, so the injectors don't get hot and go whacko...

Here it is done w/ your info:

850 X .6 510
----------- ----- = 100 PPH injectors.
6 X .85 5.1

Turn them on 90%, and the required size is 94.4 PPH.

Given the short duration of WFO operation, I'd go w/ 95's...
BTW, I have about the same engine combo you are talking about. I use the 95's....

 

[strikeeagle]

I like it when other people have to buy stuff...

 

[Chuck Leeper]

Originally posted by strikeeagle
I like it when other people have to buy stuff...

Me too! Like the Christmas present you bought for me!!

BTW, why hasn't it shown up by now???

Happy Holidayz

 

[9SECVSIX]

Facts on 83,s

Larry i,ll shoot my experience with the 83,s at you. My car made 750-800 RWHP( do the math) with the A/F ratio at 11.2 the inj,s running in the low 90% range, I run a fuel cell, 2 fuels lines and 4 fuel pumps, (70psi@WOT) The car tips the scales with driver at 3400 lbs and runs 145mph, IMHO am to the limit on the 83,s even with my potent staged fuel system.
Hope this helps.

9sec.

 

[strikeeagle]

Chuck,

Your 40 under crank is on the way!!!

 

[Larry]

Thanks for all the input guys- Larry