Is a fuel pressure regulator required?

[gslender]

I'm not saying the install is good. Just saying that having a battery 12v unswitched with no relay etc is normal. If it's wired wrong but looks neat using the stock loom or it looks a mess but works is irrelevant other than if it works or not. ECU won't flatten the battery quickly but all cars unused will eventually end up with flat batteries.

[The American]

Back to original topic remember that an NB8B/NB8C has a 60psi static FPR (it doesn't reference manifold pressure) in the fuel tank. So you will be losing fuel pressure relative to boost. It's a returnless system so a pain to change as you need to add a return line and modify/replace the rail fuel . I've got a NB8A factory return line and rail in my car. Then a fuel rail adapter on the rail and the SARD FPR. It can be tuned around but the injectors will behave smaller at high boost/load as the pressure drops (e.g 60psi - 14psi manifold pressure = 46psi of actual injector pressure). Most people aren't running huge boost so I'd leave it as-is for a street car. If your going drag racing later running 30psi on a big turbo I'd worry about it though That 416 should also be a nicer street pump than the 255 walbro, they got much quieter in recent generations of the submerged pumps.

Thanks Hellmun, that's useful information.

[The American]

I've ended up with an early NB fuel sender unit and return line. The fuel rail has been modified to accept the return line. A HKS fuel pressure regulator is mounted where the factory damper was located.

[chrons_rotary]

No turbo mx5 I've ever tuned needed an upgraded fuel pump. Ever.

You forgot mine, but that was because it was dying.

[The American]

The pump and reg are a waste of money. ID1000 are almost certainly overkill also.

Dann

It's probably difficult to compare the old tune, and *alleged* power out put and tune with the new one. However, IF the old tune was appropriately close to the limits of the system and (IF) the new tune is too, the fuel system adjustments (injectors, AFPR, return system) produced a very small (if any) return in KW.

If it was previously producing 185kw on 98, I thought it would produce more than 191kw on E85. There really is no valid before and after done on the same dyno, and this was not possible because the boost control via the old ECU was not functioning properly. It's altogether possible that the Allstar Tuning dyno was very optimistic, or the tune was much more aggressive, or...etc

So Dann, although not beyond reasonable doubt, on the balance of probabilities, you were right!

[The American]

The tuner mentioned that there was more power there with an additional 2psi, but only 4 or 5 Kw, and intake air temps were starting to rise. He suggested that the turbo was at the limits of its range. I don't quite understand this as yet - if the turbo is still able to make additional boost, how does a higher IAT indicate that the turbo is running out of puff?

[gslender]

Because it would be spinning harder to make more pressure. Harder = hotter


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