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Am i thinking right>>>Fuel Pump advice?


Jersey

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Jersey, do you have another intake manifold you could play with? If not, I have one that you could have. I think it's better to have a custom fuel rail and mod the manifold to accept o-ring injectors. This way you have a huge supply of cheaper injectors to choose from. (look on GN boards) I think I had the machine work and custom rail made for about $100. Then you can change to any number of different size injectors when you upgrade the engine management, turbo, or intercooler.

 

Joe

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Jersey, do you have another intake manifold you could play with? If not, I have one that you could have. I think it's better to have a custom fuel rail and mod the manifold to accept o-ring injectors. This way you have a huge supply of cheaper injectors to choose from. (look on GN boards) I think I had the machine work and custom rail made for about $100. Then you can change to any number of different size injectors when you upgrade the engine management, turbo, or intercooler.

 

Joe

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No, just the one that's on the Z now. I'd really appreciate the manifold if you're willing to part with it. That would be great. As soon as i get this I.C. in, hopefully by tomorrow night it'll be done, one of the next things i was thinking of doing was to build a custom fuel rail and upgrade the injectors. I was going to order the rail from Arizona Speed and Marine, tap it for the upgraded injectors and do the welding it myself. I like to save $ when i can and i learn new stuff as i go. As long as i have the time and resources to do the job, i enjoy spending some time in the garage figuring it all out. Time is the toughest part of it all as i'm sure you're well aware. I'd love to play around with porting/re-threading an intake. Appreciate it. I think i'm going to take a run to Island Wednesday night if all goes well this weekend. Any plans? Be great to put some names to faces and see some nice Z's, like yours. Hey, I'd even like to see that GN tear up the track a bit and teach us all a lesson!!! ha. I'll make a new post on Monday to let anyone that may be interested in showing. Maybe we can show some Z speed there. Possibly see ya Wednesday night?

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Hi

 

We have similar cars! Mine is a 1973 240Z, L28ET, 240SX TB, fuel rail, stk injectors (ECU, fuel pump & lines, FPR, turbo), 1975 gas tank, 1981 5speed, R200 3.9 , 3" Exhaust - no muffler, Eclipse BOV, 225/50/14, lower springs. CV's SOMEDAY.

 

I run the car in 30 min. track races. Last summer at 10 psi w/o IC the head gasket blew out. All piston holes were egg shape and the edges were raw from detonation. I replaced the stk gasket with HKS 2mm to lower CR and ARP head studs. Now it will outlast the rings. Before we can hear pinging, it is happening! Luckly Nissan built a strong block!

 

I have now added a Porsche IC and intake temperature dropped from over 165 to 85F, usually 5F over ambient. It depends on how long boost is on. I upped the boost from 10 to 14 at the turbo. I had 2 boost gages so I hooked one up at the turbo and one at the manifold. The results were surprising. The turbo always put out 14, but the manifold showed 7, 10, 12 inconsistently. To get to 12, it seemed I had to poke it twice. This might be caused by the cooling of very hot air in the IC.

 

At the dyno we got 225 rwhp but it was very lean above 4500 so the Hp could be more. The injector scope showed almost no recovery period. Fuel pressure only reached 43.

Conclusions:

- time for a new pump.

- at over 12psi the ECU is firing the injectors too much. (The AFM spring has been adjusted. )

Suspicions:

- stk turbo produces a lot hotter air above 12 psi.

 

I backed the boost down to 12 and the manifold shows a consistent 11. There now seems to be a linear relationship between turbo psi and manifold.

 

I highly recommend a FP gage. I mounted one on the wiper cowl with the braided line under the access door. If I don't need to watch it, I remove 2 screws and fasten it to the strut tower.

 

Have you gotten the Walbro GSL-392 yet? How's it going?

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Guest Zcarsmakemyheadhurt

Yea that's what happens when you load up on Nitro on a dragster then light it up. Good idea with the fuel rail Len and yes you guest it I have the raw rail in stock now! Its easy and cheap give me a call.

 

Alex C

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