Fuel injector/base map questions
 

Ok, when I ordered my base map for my ltx8, I was planning on running a stock ser4 turbo engine with stock ser 4 turbo so I told John at Rx engineering that I would be running 550cc primaries and 720cc secondaries. so that is what the base map is for.

I have since decided to use a hybrid ser5 turbo (bnr stage 2). I was told this turbo would put down about 320 rwhp from bryan at bnr. I probably want enough injectors to handle 400 flywheel horsepower just incase I upgrade later. Anyways, here are my questions.

1. If I change injector size now, will the base map still get me up and running? I'm planning on putting around on the base map for 1000 miles while I break in the motor without boosting.

2. I am debating what size injectors to use. Should I stick with the stock primaries and go with larger secondaries like 1200cc or something? Is this too much fuel? Maybe 890 secondaries? Is it a bad thing when there is a big difference between primary and secondary injector sizes? Or will the microtech make a smooth transition?

I do have 2 gsl-se injectors that were tested at 720cc (not 680 as often said to be). I was thinking maybe 4 720's? This brings me back to the question of if I change injector sizes, will this make the motor not run right on the base map?

I was kinda thinking it would and for that reason, I was gonna keep the primaries stock 550cc and just go with much larger secondaries since I should only be in the primaries during breakin right? If I keep the rpm low, the secondaries will not kick on?

Then after break in I am gonna get the ltx8 professionally tuned. I only want to put in injectors once if you know what I mean.

thanks for the input.

The base map should get you up and running, however it might be pig rich. Might be smart to put the mixtrim down a couple of percentages.

I dont know exactly what size injectors you should run, but the ltx8 can make a smooth transition, it only takes some time to figgle the injector staging out.
You can stage the point where the secondaries come in, it depens on a lot of factors.

I think when you do a search over the boards you can find a fuel calculator. Im runing 850 primaries and 1680 secondaries. Goal is to get 500HP. when using the rx-7.com fuel calculator I would say 720-720 is somewhat lean, go for 720 primaries and 1000 secondaries.?? Maybe some others can chime in here.

Regards
Rogier

Thanks for the info, seems not many people frequent the Microtech section of this forum. Hopefully some more ideas will come in
.

Yes, its somewhat dead here, a year back there was the forum on microtechefiusa.com but thats gone also i believe.

^^^^

had any luck yet? Otherwise PM some members

Stick with 550 primaries. Go with 1600 secondaries (they are cheap, and leave room to "grow"). If you went with 4x720cc of fuel, you would barely have enough fuel for 400bhp... besides, you would run rich in vacuum with your current map.

PM me if you need some tuning done. I'm in Pasadena :)

hmmm, before reading your reply I had decided to go with 550 primaires and 890 secondaries (same overall cc as 4x720). Now you got me thinking. I will be on my current set up for quite some time I hope. It's going to be in a first gen so it will be a rocket, even at 300hp. I think my turbo is capable of approx. 320-330 bhp at 14psi per Brian at BNR. I plan to run 12psi most of the time. I'm not sure if that power figure is on a ported motor or not. Mine will not be ported for awhile. It is a brand new motor so I'm not takin it apart until it needs a rebuild which hopefully isn't for awhile. The turbo was just rebuilt by bnr also so it won't be getting upgraded any time soon. I do see your point on injector size though as they would probably cost only a little more right? It wouldn't be a problem running alot less fuel than they are capable of?

I once read that you don't wan't that huge of a difference between primaries and secondaries on a street car. Any truth to this? I think the thread was saying it's ok on drag cars but not on a track car or street car because the transition might not be smooth? But if it's tuned properly I don't see the problem.

I just might call you up when it's time to tune, or maybe even for the install :) I will be starting the engine swap this week if all goes well.