Im gonna be buying the GT 35/40 soon but I dont want to upgrade my fuel system right away because I just did not more 2k miles ago last winter, Im using an aftermarket FPR, supra fuel pump, stock primaries and 1300 secondaries, What kind of boost do you guys think I will be able to run using this set-up. I just dont want to bolt it all up and then be foeced to upgrade the fuel system again, if thats the case I will just buy the GT 35/40 and wait until next winter to install it when I fell like upgrading the fuel syst again...
Thanks for any advice.

 

When your car is down for the single turbo install the intake manifold will have to be off any way, so why not just drop the stock 850's in the primary slots? That should help alot. The supra fuel pump I don't know anything about though so can't help there.

But to answer your question. I wouldn't feel safe running over 10psi on that setup.

M-P

 

10psi?!? You can run more on stock injectors!

I was running 15 on the stock twins with stock injectors at about 96% duty.

You should be able to run 15 psi easy. I'm going a 35/40 conversion myself and dumping in 1600cc secondaries. Have a Walbro pump and stock primaries. I'll be tuning for about 17.

 

How you pulled off 15 psi on the stock twins and fuel at 96% injector duty is amazing. My car ran at 12.5 psi on the same setup hit 98% injector duty on the dyno and was running AFR's around 13.8. I got scared and put 1600's in the secondaries, upgraded the fuel pump and fpr, and went Non-sequential. I was running 15 psi at about 70% injector duty.

You got to remember that the GT35/40 is going to flow ALOT more are than the stock twins in sequential. I just got a single and am scared my setup may not be enough (may need the 850's back in the primaries and a bigger fuel pump) Correct me if I'm wrong, but his setup shouldn't be trusted with alot of boost.

M-P

 

Yea thats what I was thinking also, 10-12psi with my 1300's and stock primaries, Lets say I kept the 1300's and went with like 900-1000cc's in the primary spot ? I only want to eventually run the GT 35/40 at 17-18psi...
What kind of fuel setups are you GT 35/40 guys running ?

 

Correct me if I'm wrong, but aren't the primaries only used by themselves for a short period of time (like when the motor isn't seeing boost)?

At any rate, that's what I was running. Tuned by A-spec tuning (plug ). Car ran beautifully! I'm trying to remember what I was tuned to (AFR) but can't for the life of me remember. I thought the datalogit held duty cycle #'s, but it doesn't seem that they're there.

I was hitting 12-13 on a modded stock ECU, but retuned to 15 on the PFC. I was actually peaking at 1.08 bar on occasion. Usually on a colder night and when running really hard. I've tracked with that setup with no issues. Kept pace with an '03 Z06 with only an exhaust.

At any rate, yeah, my duty cycles were high, but I don't care. 96% was peak through all kinds of driving conditions. Don't have to worry about that now. Of course, all cars are different. Maybe mine was just able to handle that. Reman with about 20-25k on it now. Idles at about 18 mmHg.

 

ok guys, i just got my car back from getting tuned, finally. we still have some tuning to do, but i'm pushing .8bar absolute. (10psi) with 550's and 1600's and my duties are still way low. with the 1300, you should be able to run 15psi. you can use the fuel calculator on rp's website to figure out how much hp those injectors will support. with 550's and 1300's at only 80% duty, they will support about 447hp. (850pri=519hp)
back with my twins i ran 14psi manifold and had high 80's duty cycle. running higher than 1bar is the question on the 1300's.
twintri- dont put that big of primaries in. stick with 850's in the primary.
there are lots of arguments about 1300 vs. 1600's. but i opted for the 1600's. yes, you have to buy a new rail, but you get stock 1600's not 'modified to' 1300's. i would think, and dont flame me, that the 1300's would have a higher failure rate, since they are modified 850's. i just like the idea that my sec. came strait from the factory and in my car just a little piece of mind. i also had my 550's cleaned and flowed by rc eng. i might have to upgrade my primaries cause i'm making tons of power at only 10psi. but we'll see.
just my .02

 

So you think 550's & 1300's with my fuel pump would be safe to run lower boost like 10-12psi or so? Im obviously going to find out when I go get tuned what is possible and what is not but I want to know before even putting on the GT35/40 kit that 550 & 1300 will be safe at all... I thought the 550's were on and then the 1300's come later but the primaries still stayed on...? Maybe im wrong... So 447hp with my setup at 80%... I would feel safe running up to like 93-95% duty cycle anyway so its starting to sound like I'll be pretty safe with my setup...
Thanks guys !

 

Oh also my mods ar as follows if that will help...
Pettit large streetport (9k miles)
3mm apex seals
silicon coolant seals
DP, MP, CB
K&N Intake w/hard pipes
Koyo Radiator
Greddy FMIC
Greddy elbow
HKS SS BOV
1300cc secondaries
FPR
Power FC
AVC-R
Supra fuel pump
Pulley kit
Vac. hose job and all the block offs
Also I cant think exactly what the duty cycle is I run now but I run the stock twin w/clipped turbine blades and I run 14psi and i think my duty cycle is like low-mid 70% I think...

 

I talked to rx7store today and they feel I would be good to go with this setup at around 14psi or so and I should definitly go with the 850cc primaries if I want to go with anything more than 14psi on the 35/40