I'm getting ready to put a Garrett tp38 on my 305TPI. My friend says I can get a fuel management unit instead of getting bigger fuel injectors-anyone know anything about this?

 

Well, the FMU will take care of adding fuel when it senses boost so the car dosnt lean out on boost. Still very possible the stock injectors can't handle the added flow and the motor leans out anyway. Dont necessarily have to do both in all situations, but you should do the FMU and then calculate where your injectors will be and if its above 80% duty cycle then you'll want to upgrade the injectors too. LB9's have 19# injectors, which are somewhat small, not sure what their maximum power rating is.

 

Have you considered the timing control when in boost?

 

no,what do I have to do there?

 

You have to do something, wheather it be a boost retard box or a diff ecm. If you don't have an FMU or boost retard box, which I don't like either one, look into a 749 ecm swap. No FMU or boost retard box required. You also need to think about a fuel pump upgrade, the stock one isn't all that good for boosted apps.

 

if i get 36lbs injectors and a 255 fuel pump will it be good?

 

That should be plenty for a 305ci with 6-7psi

 

I agree, you should do something about detonation control. So either a way to retard timing or maybe inject something (water/meth, etc), maybe even just really high octane gas. I'm still using the stock ECM so I use the MSD 6BTM to help control detonation by retarding timing per psi of boost. IMO this is not the most accurate way to do this but it does work. Someday I'll change up the ECM so everything is integrated.

 

Yes, for mild boost as stated above. You will need to reprogram the ECM to work with the larger injectors, and you will need an MAP based injection system that can read positive manifold pressure.

FWIW, I am running the FMU/BTM combo for my TT IROC running 6psi of boost from two T3/T4 turbochargers. It works well, but as stated above custom ECM tuning is going to be the best route. The FMU is best suited to a beginner because it is easier to work with IMO. My 350TPI runs Ford SVO 24# injectors, a Vortech Super FMU (its more adjustable) and an inline booster pump. I still have the stock in-tank pump feeding the booster, and the ECM/chip are stock. The 24# injectors work nicely and set no codes if you turn the base fuel pressure a little lower than stock. My combo works and is easy to install and tune, but I plan to do larger injectors and custom ECM tuning before I turn the boost up.

I would suggest the Cartech/Begi FMU for their excellent adjustabilty and ease of use. They are more expensive than some cheap units sold on eBay, but well worth the extra price IMO. You should be able to find them for far below the $259 list price.