Ehughes

I have relocated the coolant reservoir (plastic) to the firewall on the passenger side near the overflow tank. It is still at about the same level (vertically) as before.

I also capped the water supply and drain lines at the motor for the stock turbos when I installed the single.

Any problems with these mods?

FormerPorscheGuy

Sounds fine to me.

Tom93R1

iTrader: (2)

??? The coolant reservoir is the same thing as the overflow tank. Do you mean you relocated the AST?

Ehughes

Too much terminology. Yes. Factory plastic AST is on the firewall now. Before it was mounted on my PFS IC.

rynberg

The only problem is you should have replaced the plastic AST with a metal one.

Ehughes

That is on my list of things to buy......the never ending list. Let's just hope I get it started today after 18 months of work!!

Thanks.

cewrx7r1

iTrader: (2)

Do not replace the AST, remove the useless piece of junk as most serious owners of modded engines have done. Do a search on how to do it. It is also posted on some RX-7 sites.

JaNusSolSumnus

I prefere to keep it only because it helps collect the air in the system much better than without one... this way you are much less likely to suffer from air bubbles in the motor.

Cewrx7r1, what are the negative effects of keeping an AST compared to removing it other than the possible 1lb weight gain to your car? I dont see any ill effects other than to better assist your cooling system. I'm still learning though so dont take my post as one from an 'expert'.

~Kris

Ehughes

I have read many threads on the pros and cons of keeping vs. eliminating the AST. However, none have dealt with relocating it.

I chose to keep it for the same reason that "JaNusSolSumnus" stated. I realize that the plastic AST is a weak link. But when it breaks, I'll bypass it an have the new cap on hand.

cewrx7r1

iTrader: (2)

The AST does make it easier to get rid of air bubbles after changing radiator fluid. Without it, it takes about two three driving cycles(drive car, let it cool down, and refill fluid) for all air to get out. It would eventually get rid of it all by itself through the overflow valve and tank.
I just speed up the process. Most I ever had to add back was about 1 cup of fluid.

Thus the disadvantage is very small and only occurs immediately after a cooling system refill. It all depends on your cooling system refill procedures.

Even with the AST, it takes a while to get the cooling system topped up.

The advantages last for ever: less weight, less engine compartement clutter, less cost, and more reliability.

All my friends with modded engines have done this and never had any problems.

Along the same line of resoning (to get rid of useless parts) is the FPR solenoid. It serves no real purpose even though the manual says it is to help prevent fuel
vapor lock. DOH, we have a high pressure pusher fuel pump system! All it can do is give a slightly higher cranking fuel pressure. We have never had vapor lock problems even down here in Houston summers. It is just another piece of equipment not only needed but failure of can blow your engine.

DamonB

I like to keep the AST because my cooling system holds that much more coolant with the AST in place than it would without it.

It makes a difference in hot start conditions on my car (stock motor and ecu). My car came back from the shop once with the FPR solenoid bypassed. I noticed right away during hot starts the idle was always lumpier and took a few minutes to clear up. I noticed the solenoid being bypassed so I hooked it back up correctly. With the FPR solenoid in place the lumpy idle problem during hot start doesn't exist and idle is always perfect once again. FWIW this was also with brand new injectors, FPR and FPD. The idle issue was due to the FPR solenoid being bypassed.

IIRC correctly from investigating the manual the FPR solenoid is only used during hot start, otherwise the system behaves as if the solenoid doesn't exist. If you don't daily drive your FD you'd probably never notice the difference.

Ehughes

Would the effect be the same with an aftermarket FPR. I have installed the SX FPR with the Comp FP. Although, I have not started it yet.

I would love to eliminate another part if possible though. It seems the FPR would give you a layer of protection between the FP and injectors to keep flow consistent. But...I am far from an expert.