Qbuilt

Hi everyone,
I just was wondering about anyones input on my current plans.
I have an s4 manifold and turbo that im sticking to the side of my stock 12a and am planning on boosting the nikki carb. I have a machinist friend who is making me a 1" thick adapter plate to avoid any clearance issues. I have also modified the stock intake as well.
I have a dismantled nikki right now and i am going through it to determine all the orifices and whatnot i have to block up.

I am planning on running 5psi to start to a max of maybe 8. I am not running an intercooler for now but probally will once i have all the kinks worked out and it is running right.

I just have a few questions. I do know of a few fuel pumps that would be good for this but what am i really looking for as far as specs?? 255lph, 80gph,...??I know that with a rising rate regulator i need to have a pump capable of base pressure plus boost pressure. So at least 25 psi to be safe.
Also what exactly should i do about a blow off valve, boost control, wastegate acuation??

Thanks for any input guys and gals.

FB II

that's not where the issue is when boost prepping a nikki...


not gonna happen unless you have a stock exhaust... or PORT the wastegate massively. look more for a minimum of 10 - 12psi after creep with higher flowing exhaust.

also,

just get an EFI pump and you'll be set.

do not worry about boost control unless you actually port the wastegate.. because unless you do that... you won't have any control as is. so run the line from compressor to the gate.

keep it simple... don't run a bov!!! but if you must.. get a DSM, Supra, TII, etc... stock one to keep it on the cheap.

oh and you're going to need more than a 1" thick adaptor plate i believe. epsecially if you are doing it where the turbo meets the manifold.. i think you need about 3" there. this is... if you are using the stock nikki manifold, you say you modified yours... but i dunno if that means you prepped it to not bleed boost or if you chopped it down a **** load

have fun man, it's worth every bit of energy invested!

autopaul

quote "just get an EFI pump and you'll be set."
ok well i dont know much about boosting a stock nikki, but i really for some reason think that getting just some efi pump would work, im pretty sure these nikkis like to be run at lower psi, and just get a pump that flows allot,

i know allot of people use 255lph pumps for fuel injection turbo applications, so i think that would be plenty for a carb turbo,
i would do it properly and get a rising rate fpr, and having a freshly cleaned carb sounds like a great idea, if your planning to go turbo,

on the boost creep subject i would be careful im not sure on a stock port 12a how they would react, but since its high compression i would be inclined to take the turbo apart and port the wastegate allot like was said, or again i would do it properly to begin with, and get a custom manifold made, and maybe use an external wastegate,

again this is just my opinion, i dont claim that it is the perfect way to do it, just the way i would do it,

-Paul

FB II

alot of people with CARB turbo setups just rock a stock gsl-se pump. the flow will be there no problem. now if this motor he was speaking of was massively ported or capable of more than 250rwhp then you gotta start worrying about higher flow aftermarket pumps. but for such a mild setup... any good efi pump will seriously do. what he doesn't want to get is a carb pump. the flow may be there but the pressure wont. yes the nikki doesnt want but 3 - 6psi at idle... this is where your fuel pressure regulator comes in and a massive return fuel line. problem solved.

i'm rocking an msd high flow EFI pump. pushes well over 40psi but i regulate that down to 4psi to my nikki with my aeromotive 1:1 fpr.


and the boost WILL creep. there is no doubt, probably not as bad with that stock s4 manifold and especially if he has a restrictive exhaust.... but if the number 3 and inch are in the same sentence when it comes to his Turbo back setup, then control is out the window until wg is ported.

the external wastegate idea is the best.. but then for the money you would be putting in to the manifold and wastegate and boost control.... you might as well buy a T4 turbo that will make more power.

it really all depends on budget.

Qbuilt

FB II,
I was looking at how exactly the stock setup controls the wastegate and it appears that pressure is applied to the wastegate diaphram via the positive pressure side of the turbo, soo therefore i think a preset pressure is designed into the spring or rubber inside the diaphram opening the wastegate when it sees this amount of psi. Right?????
So now my question is if i were to install a boost conroller which installs inline with the positive pressure outlet and the wastgate diaphram inlet, there would be no way to turn down the boost unless i was adding pressure to the wastegate to open it. But that can only happen at this preset level determined by the spring or what not. So i could only control it at a higher level above 9,10 psi providing the wastegate is ported????
In order to run low boost im am going to need an external wastegate therefore it is totally controllabe, correct?

Do FC's have inline pumps similiar in design and flow to se pumps? I have access to a few of these

Thank you for all the info guys

FB II

lol... yes. a "boost controller" goes inline from the compressor to the wastegate diaphram. easy as that. you boost can only go as low as the wastegate allows. a boost controller can only raise pressure. you can get under 10psi if you port the **** out of the wastegate like i did. i'm able to get a steady 6psi if need be... but wheres the fun in that ?

an FC pump is an in-tank pump. not inline. if you modify your gas tank you can use it.

Qbuilt

Fb II thank you.

trochoid

iTrader: (6)

Before one buys an efi fuel pump, for a carb application, make sure that you find an fpr that will take the higher pressure. Many of them will not. Personally, I would go for a decent high flow, low pressure fuel pump. Many can be had for less money than the SE efi pump.

FB II

i think you missed the point... a low pressure pump is what he needs to stay away from. it's safety here that is the issue at hand. a low pressure may JUST BARELY get by with enough for the set amount of boost... but that isn't really a good idea. an efi pump will be NO ISSUE... i can GARUNTEE this. it's been done countless times even on n/a setups. guys who carb their gsl-se's keeping the stock pump and just using the right fpr.

the BEST choice FPR (in my opinion) is the AEROMOTIVE 13302; 3 - 12 psi base pressure and has a 1:1 ratio under boost. amazing quality!

the mallory 4309 works, but the one i had took a **** real quick and mallory tech support is the worst.

ofcourse the key to all this is your Return line coming off of "said" regulator. make it atleast the same size as the feed line. i ended up going one size bigger. i'm able to get my 40+psi pump down to 3psi as needed. not a problem at all. this way... you know fuel won't be an issue.......... atleast the fuel going to the carb. now tuning the carb is another story

trochoid

iTrader: (6)

My bad.

I keep forgetting to add the 1:1 rise over base pressure for boost, which puts most low pressure fuel pumps on the short side. Even my Mallory Comp 140 pump has an internal bypass at 12 psi, which would limit boost to 5 psi, with one to spare on a Holley.

I'm not suprised the 4309 failed, iirc it is not designed for fi pressures. I need to find my paper work for it to confirm that. The Comp 140 flows so much fuel, it requires a 3/8" return line, when the internal bypass is removed and used in a return style system.

If I manage to go fi and Megasquirt with the 12a-bp this winter, I will probably add a surge tank and fi pump in the engine bay. To me, that is a much safer way to do the fuel system, for boost, even with the SE tank. Seems to be the preferred setup of those crazy Aussie guys, who are 2nd only to the PR's. We, unfortunately come in a distant 3rd when it comes to hanging off the edge of rotary performance.

FB II

surge tanks are such a great addition. alot of people don't realize this. and running low pressure high flow pumps to high pressure efi pumps is also another good thing to do for that secured flow as you stated

REVHED

Yeah, it's a very rare over here to see a fuel system that doesn't include a surge tank.