The Definitive "VVT swap into 90-97 chassis" Megathread.
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From: Sunnyvale, CA
There should be no ambiguity or questions about the fuel system. It is not dependent on chassis or wiring or what intake manifold you use or anything else. For any NB motor in any NA chassis, you use a 99-00 rail and a USDM 90-93 -OR- EUDM 99-00 FPR.
Fuel system:
Use a 1999-2000 fuel rail and a 1990-1993 USDM fuel pressure regulator installed upside down with the fuel outlet bent straight to clear the intake manifold. No other combination of USDM parts will work. The 90-93 fuel rails are too short, the 94-97 rails have incorrect mounting tabs, and the 01-05 rail places the fuel pressure regulator in a spot which interferes with the cylinder head. The 94-97 FPR places the pressure reference in a spot which interferes with the cylinder head and the 99-05 regulators do not have a return line.
Use a 1999-2000 fuel rail and a 1990-1993 USDM fuel pressure regulator installed upside down with the fuel outlet bent straight to clear the intake manifold. No other combination of USDM parts will work. The 90-93 fuel rails are too short, the 94-97 rails have incorrect mounting tabs, and the 01-05 rail places the fuel pressure regulator in a spot which interferes with the cylinder head. The 94-97 FPR places the pressure reference in a spot which interferes with the cylinder head and the 99-05 regulators do not have a return line.
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From: Boston Mass
Perfect, Thank you SAV.
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Have a question on fitment of injector harness with squaretop and aftermarket fuel rail from Radium. The 97 injector harness appears much bulkier than NB injector harness that was designed to lay under the IM as opposed to above the fuel rail as the case in NA.
I have to take the squaretop apart to get to connect the injectors anyway..is there a recommended NB injector harness swap into NA?
Thanks
I have to take the squaretop apart to get to connect the injectors anyway..is there a recommended NB injector harness swap into NA?
Thanks
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Thread Starter
Joined: Nov 2006
Posts: 15,442
Total Cats: 2,106
From: Sunnyvale, CA
Have a question on fitment of injector harness with squaretop and aftermarket fuel rail from Radium. The 97 injector harness appears much bulkier than NB injector harness that was designed to lay under the IM as opposed to above the fuel rail as the case in NA.
I have to take the squaretop apart to get to connect the injectors anyway..is there a recommended NB injector harness swap into NA?
Thanks
I have to take the squaretop apart to get to connect the injectors anyway..is there a recommended NB injector harness swap into NA?
Thanks
It may depend on which version of the 99-00 fuel rail you have, but the 94-97 FPR doesn't work in all cases. The 90-93 FPR does. If you want to avoid bending parts, use the EUDM 99-00 FPR which is designed for the application.
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From: Chicago
fuel rail
My injector can’t be turned 90 degrees due to clearance with the head. I guess will need to run it at 180 degrees and sneak the plug in the tight opening. Can someone confirm that they have also this much clearance with the squaretop.
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Thread Starter
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From: Sunnyvale, CA
The injectors were never oriented up like that, even from the factory.
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From: Chicago
I may have confused 97 with 99. On the NA8 they were straight by the head as there was more room between rail and head. Please correct me if I am wrong as i am a noob and being a bit OCD.
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https://www.miataturbo.net/useful-sa...04/#post152397
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Got a question, running a BP6D in a 96 chassis. Confirmed it has fuel/spark/compression. Loaded the 99-00 startup map from MSPNP.com MegaSquirtPNP by DIYAutoTune.com The vvt actuator is wired but not hooked up as we would like to get it started first. Using a stock oem 99-05 trigger wheel, that is installed correctly. Stock injectors, 99 fuel rail, 1.6 regulator, skunk2 intake. We were able to get the original motor running on the same ecu before pulling it.
Included data log and composite log.
Let me know what you think it is.
Included data log and composite log.
Let me know what you think it is.
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Thread Starter
Joined: Nov 2006
Posts: 15,442
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From: Sunnyvale, CA
Yes, it fires down. You're basically using the EUDM parts in their original EUDM configuration.
On the S1 car I'm building (VVT motor into a '94), I used the VVT rail with an adapter and an external FPR. It is a tight fit, but it works. The adapter lets the outlet fire at a ~45deg aimed forward, which is the only space a fuel line would fit into. For folks who were going to use an aftermarket FPR anyway, it's a good option. I'll post some pics here and in my current S1/ST4 customer build thread later today.
On the S1 car I'm building (VVT motor into a '94), I used the VVT rail with an adapter and an external FPR. It is a tight fit, but it works. The adapter lets the outlet fire at a ~45deg aimed forward, which is the only space a fuel line would fit into. For folks who were going to use an aftermarket FPR anyway, it's a good option. I'll post some pics here and in my current S1/ST4 customer build thread later today.
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Thread Starter
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From: Sunnyvale, CA
This is our regulator adapter on a VVT fuel rail with an Earl's Vaporguard 1/8" NPT to 5/16" 90deg fitting. The green goo is Gasoila E85 sealant. There's no way to get a standard FPR in this spot with clearance for vac/fuel hookups, but you can get the NPT fitting oriented correctly so it just barely sneaks out of there. This is a good option for people who are going to run an aftermarket FPR (something like a Fuelab 545 would go inline between this and the return line) since you can use the OEM VVT rail that comes on the motor instead of sourcing a combination of US parts or a hard-to-find EUDM 99-00 setup.
Adapter: Trackspeed FPR Adapter
Fuelab 545-series: Fuelab Fuel Pressure Regulator
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Can we add to the Alternator section of the first post that you need a different lug for the 94-97? It's easier to "relug/crimp new lug" it when you have the engine out.
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From: Chicago
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