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Discussion Starter #1 (Edited)
As many of you are probably aware, the stock diverter valve (DV) is a bit of weak point on these engines. While many have had success using the GFB DV, it still relies on Fiat's solenoid, and plenty of 500 Abarth owners running tunes have still found them to be lacking in terms of their ability to hold boost. I decided to get the full monty, skip the GFB, and pick up Forge's atmospheric BOV. This ain't no plate, this is a full blow off valve. I picked it up from EuroCompulsion, found here:
https://shopeurocompulsion.net/collections/fiat-124-engine/products/forge-motorsports-blow-off-valves

I went atmospheric because I didn't want hot turbo gases being recirculated into my nice sealed intake system. Also, it sounds delicious. I can work on some recordings this week if you guys are curious.

While I don't have a full DIY for you all, I do have a link to some great instructions for the 500 Abarth, as well as some notes that are specific to the 124. Sincere thanks to SuperTony, who's over on a 500 forum I'll refrain from naming for now. Here's the link to his instructions:
http://500madness.com/500madness/pdf/ForgeBOV.pdf

Now, for the 124 specific parts:

The brake booster port that he's showing is at the very back of the engine. If you're like me, you might think that removing the wiper cowl would allow easier access. Don't be like me, the cowl is a siren. There's nothing under there except for more covering and lies. If you have an Abarth, take off the center strut bar piece, and be grateful that taking that center piece off is as easy as it is. You'll be able to reach the port with the hose easier than you think. I believe in you.

Here's where it is:


It's the red clip that is at the very back, directly in line with the oil cap. Here's a close up.


Use a long, skinny flat-head to pop that red cap, just like the ones that go to your intake.


One 6mm hose gets attached to the port. Put your zip-tie loosely around the hose before you attach it for easier tightening once it's all the way on. The metal piece that ships with the Forge BOV is going in to the red-clip hose. It fits perfectly. Here's how it looks once it's secured:


The instructions above are really good at explaining the routing with the T-pieces, but let me know if you need clarification. Here's how the 6mm T-piece goes in the back. The tube pointing towards the camera is the 6mm to 4mm reducer piece.


I was extremely nervous to cut the line running out from the bottom of my turbo. It looked way too big for the 4mm T-piece to fit in, but it's got a very thick wall, and the T-piece fits securely. I tried to cut as far from the turbo as I could, just to keep it away from the heat.


The solenoid plugged in to the factory DV is taken off by pulling the yellow part straight down, then pushing in at the bottom of the black clip. Here's the clip with it unsecured.


I mounted the solenoid with the Forge bracket serving as a washer to where the evap hose going into your intake mounts on the front of the engine. I flipped it upside down after this picture, and the stock engine cover is able to go back on normally. It also pulls one of the hoses out of the way of the oil filter for easier removal during oil changes.


Past that, the instructions from Super Tony are spot on. Please let me know if anyone needs any clarification. This was far more daunting looking at the Forge instructions than it actually turned out to be.

I'm super happy with this mod. It's a huge improvement to smoothness and driveability, and I'm confident it will hold all the boost I'll be throwing at it as long as I'm on a GT1446 turbo.

Edit: I also forgot to mention, and the instructions don't say anything about it, but I'd recommend very lightly oiling the o-rings that go on the back of the valve.
 

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Switching to VTA BOV has no effect on the tune, and does not require a tune?

I come from the Subaru world which is very unforgiving to mods (without a tune)
VTA especially is a bad idea on them.

This engine is more forgiving for that?
 

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Discussion Starter #5
Switching to VTA BOV has no effect on the tune, and does not require a tune?

I come from the Subaru world which is very unforgiving to mods (without a tune)
VTA especially is a bad idea on them.

This engine is more forgiving for that?
The 1.4 multi-air doesn't use a MAF, it has wide-band/speed density sensors. Whether recirculating or VTA, the ECU can operate perfectly without a tune.

I'm trying to borrow a friend's GoPro for some decent sound recording. Barring that, y'all are getting some cell phone videos shortly.
 

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Other than the Fiat solenoid, what is the advantage to this over the GFB? Is this just a reliability and consistency modification or does this increase performance as well? Turbos are new to me, so I need edumacated.

Thanks and have a great weekend!

Regards,

Jeff
 

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Jeff, the advantage of the Forge vs. the GFB is that the Forge unit doesn't leak boost period. The Stock valve leaks, the GFB leaks less, the Forge doesn't leak at all. The downside of the Forge as compared to the GFB is cost and complexity of installation. Put another way, the GFB is about 90% as good and at just over 1/2 the price. I can't really make a strong recommendation for one over the other, they are both great. There just isn't a wrong choice here.

Greg
 

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I got a boost leak after installing the forge BOV.
Any idea why? cruise control is disabled and car makes a louder turbo sound when turbo trying to spook up.

I got a shop install it for me. He never got the 124 instruction but the Fiat 500 instruction.


Any ideas?
 

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Sounds like the dreaded loose connection at the diverter valve. I remember reading on the forum that it is usually coupled by inoperative cruise control. Any CEL? Make sure your guy double checks that connection. A very common issue after it has been disconnected or otherwise disturbed.
 

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Did you get the kit for the 124 or for the Abarth?

I got a boost leak after installing the forge BOV.
Any idea why? cruise control is disabled and car makes a louder turbo sound when turbo trying to spook up.

I got a shop install it for me. He never got the 124 instruction but the Fiat 500 instruction.


Any ideas?
 

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I responded in the other section also but
pretty sure the Abarth on the menu means the 500 Abarth, which has a different engine than the other 500s. For the 124, it's the same engine either version so I think you need the 124 version. I'm sure Greg can verify



I got a boost leak after installing the forge BOV.
Any idea why? cruise control is disabled and car makes a louder turbo sound when turbo trying to spook up.

I got a shop install it for me. He never got the 124 instruction but the Fiat 500 instruction.


Any ideas?
 

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Sounds like the dreaded loose connection at the diverter valve. I remember reading on the forum that it is usually coupled by inoperative cruise control. Any CEL? Make sure your guy double checks that connection. A very common issue after it has been disconnected or otherwise disturbed.
Yes I checked everything was connect and secured properly, no CEL as well

I also read that thread, but unfortunately it does not seems like it is my problem
 

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Just installed the Forge today and these notes were really helpful. Thanks @Jon. Took about 90 minutes with an oil change going on at the same time. It would have been much longer figuring things out without these notes.

I had a minor panic trying to remember where I put the OEM BOV bolts when I'd installed the DV+ and cutting the line from the turbo felt very final...

Car felt much happier with the EC phase 2 tune. Very pleased.

One question for @Greg and @[email protected].net - blue spring or yellow spring? I used the blue and the car felt pretty happy.
 

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Just installed the Forge today and these notes were really helpful. Thanks @Jon. Took about 90 minutes with an oil change going on at the same time. It would have been much longer figuring things out without these notes.

I had a minor panic trying to remember where I put the OEM BOV bolts when I'd installed the DV+ and cutting the line from the turbo felt very final...

Car felt much happier with the EC phase 2 tune. Very pleased.

One question for @Greg and @[email protected].net - blue spring or yellow spring? I used the blue and the car felt pretty happy.
Blue spring for either Phase 1 or Phase 2.
 

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Hmmm, I've been running yellow since I installed mine, as that was the consensus reached over on FT. I could've totally had this wrong for a long time. Paging @Greg and @[email protected] as well . . .
Blue spring for the Forge BOV. Yellow spring for the forge waste-gate actuator. :)
 

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I noticed some boost leak even with the Forge BOV equipped with the blue spring (the BOV was making psss psss psss sounds during hard acceleration while the engine hesitated).

I fixed it by stacking the yellow and blue springs on top of each other and cramming them both into the BOV. This is probably a bad way to do it. A better way would be to get the red spring from Forge, it's stiffer than the blue spring. Mine is on its way so my sketchy spring stacking method would have to do for now (at least I'm not hearing any turbo flutter.) Another way would be to stick some spacers into the BOV cap to give the spring some preload, but you have to find the right size. Just putting this here in case anyone else experiences this problem.
 
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