[RAIV-Z]

Before purchasing parts, check with the mfg to make sure they are not end of life. I don't believe the Godzilla BOV is still being produced. This statement is based on it not being available from turbonetics according to their web site.

[TransAm 474]

Thanks Tom.... So if you have a Supercharged engine, where you have a certain supercharger that is producing say 15 lbs of boost on a 400 Pontiac, and you build a 455 Pontiac with the exact parts, you would have to drive the supercharger faster with either a bigger crank pulley or a smaller supercharger pulley to produce the same 15 lbs of boost, do to the bigger Cu. In.

A turbo setup with say a 15 psi spring in the gate, would produce the same 15 psi, be it on the 400 or the 455 without changing anything, correct? In other words, Engine size doesn't matter with a turbo setup that is using a wastegate that is calibrated with a preset spring pressure, it will always produce the same amount of boost as the spring in the gate is good for, no matter the engine size, correct?

[Tom Vaught]

Originally Posted by RAIV-Z

Before purchasing parts, check with the mfg to make sure they are not end of life. I don't believe the Godzilla BOV is still being produced. This statement is based on it not being available from turbonetics according to their web site.

Interesting.
I went to this link that says 2016 to 2018 hardware and the Godzilla BOV is listed.
http://www.turboneticsinc.com/perfor...cts/wastegates
They list the BOV in the Wastegate section of the catalog.

Tom V.

[Tom Vaught]

Originally Posted by TransAm 474

Thanks Tom.... So if you have a Supercharged engine, where you have a certain supercharger that is producing say 15 lbs of boost on a 400 Pontiac, and you build a 455 Pontiac with the exact parts, you would have to drive the supercharger faster with either a bigger crank pulley or a smaller supercharger pulley to produce the same 15 lbs of boost, do to the bigger Cu. In.

CORRECT

A turbo setup with say a 15 psi spring in the gate, would produce the same 15 psi, be it on the 400 or the 455 without changing anything, correct? In other words, Engine size doesn't matter with a turbo setup that is using a wastegate that is calibrated with a preset spring pressure, it will always produce the same amount of boost as the spring in the gate is good for, no matter the engine size, correct?

A Boost gage just gives you a reading.
A wastegate attached to the Intake manifold CONTROLS the pressure in the intake and will raise to a given amount before it starts to release exhaust volume and maintain the given requested boost pressure. The boost pressure can be further controlled with a PWM (Pulse Width Modulated) control that allows the computer to have multiple Boost Pressure values based on a performance curve that you want.

You can use a given spring and by tricking the signal have the valve open at a higher pressure vs the spring pressure without the control system.

Tom V.

[RAIV-Z]

Originally Posted by Tom Vaught

Interesting.
I went to this link that says 2016 to 2018 hardware and the Godzilla BOV is listed.
http://www.turboneticsinc.com/perfor...cts/wastegates
They list the BOV in the Wastegate section of the catalog.

Tom V.

Maybe it's just a problem with their website.
It shows up here, but you can't add it to your cart to purchase.
http://www.turboneticsinc.com/perfor...f/godzilla-bov

A part number search for Model: Godzilla Part Number: 10765
doesn't return results. This specific BOV is still available from other sources.

I was considering adding a 3rd BOV on the intercooler.

[Tom Vaught]

Originally Posted by RAIV-Z

I was considering adding a 3rd BOV on the intercooler.

That 3rd BOV might be a good idea, I have some pictures from the Turbo Forums of a Water to Air Intercooler (passenger side installation) that it blew out the side of the inter-cooler panel. I believe that you have a Burst Panel in your Raven Intake from Mark, correct?

The third BOV might save the inter-cooler.

Tom V.

[RAIV-Z]

Originally Posted by Tom Vaught

That 3rd BOV might be a good idea, I have some pictures from the Turbo Forums of a Water to Air Intercooler (passenger side installation) that it blew out the side of the inter-cooler panel. I believe that you have a Burst Panel in your Raven Intake from Mark, correct?

The third BOV might save the inter-cooler.

Tom V.

Yes, the intake does have a Switzer Dynamics burst panel.
https://switzerdynamics.com/products/burst-panel

[TransAm 474]

Do you think 2.25" crossover pipe off of each bank, merged into the divided T6 flange would work good for me? I haven't decided 100% if I will use factory cast log manifolds that exit in the stock location and just run the pipe forward under where the A-arm and subframe meet(like 70bird did), or use a set of turbo headers. Tribal Tubes said he would build me a set for $810 Shipped with VBands, uncoated($730+$80 shipping). They are 1.75" primary and my choice of 2 1/2 or 3" collector. 16g Mild Steel with 3/8" flanges. Obviously, using the manifolds would save quite a bit of money, as where the turbo headers would probably provide more clearance for routing the Downpipe back under the car, so I am undecided at this point on that decision. For the downpipe, I'm thinking of trying to do 5" out of the turbine as far as I can, reduce it down to 4", and then split it back into my dual 3" exhaust with Dr Gas xpipe, Ultra Flow mufflers and 3" tailpipes.

[73 TRANSAM]

Do a 2.5" collector and 2.5" crossover. This way u don't need to upgrade in the future. Make sure u have a good wastegate placement. Good luck.

[Tom Vaught]

Originally Posted by TransAm 474

For the downpipe, I'm thinking of trying to do 5" out of the turbine as far as I can, reduce it down to 4", and then split it back into my dual 3" exhaust with Dr Gas xpipe, Ultra Flow mufflers and 3" tailpipes.

If you have issues with pipe clearance the pipe out of the turbine only needs to be the size of the discharge opening plus 1/2 inch on each side (top to bottom). Example" 4" opening, use a 5" pipe. 3.5" opening use a 4.5" pipe, 3.0" opening...............you get the idea.

The pipe only needs to be 3 times the turbo discharge opening for the length. Then you can reduce the pipe in sections to get to your split to the 3" pipes.

If the pipes are too large you get a slow gas speed thru the exhaust system. Make the system just big enough to handle the exhaust gas flow.

Tom V.

[TransAm 474]

Originally Posted by Tom Vaught

If you have issues with pipe clearance the pipe out of the turbine only needs to be the size of the discharge opening plus 1/2 inch on each side (top to bottom). Example" 4" opening, use a 5" pipe. 3.5" opening use a 4.5" pipe, 3.0" opening...............you get the idea.

The pipe only needs to be 3 times the turbo discharge opening for the length. Then you can reduce the pipe in sections to get to your split to the 3" pipes.

If the pipes are too large you get a slow gas speed thru the exhaust system. Make the system just big enough to handle the exhaust gas flow.

Tom V.

Ok Tom, when you say it only needs to be the size of the "Discharge Opening+ 1/2" , are you referring to the turbine wheel exducer size? If so, my turbo has an 88mm exducer turbine wheel which is 3.47", so does this mean I can get away with just doing a 4.5" downpipe right off the turbine, and for only 10.5" in length before being reduced?

[TransAm 474]

I found this nice looking flange for the T6 turbine inlet.... Its available in either 2.25" or 2.50", and you can buy them in "butt weld" or "slip fit" versions.

[Tom Vaught]

Originally Posted by TransAm 474

Ok Tom, when you say it only needs to be the size of the "Discharge Opening+ 1/2" , are you referring to the turbine wheel exducer size? If so, my turbo has an 88mm exducer turbine wheel which is 3.47", so does this mean I can get away with just doing a 4.5" downpipe right off the turbine, and for only 10.5" in length before being reduced?

Correct. 4.5" diameter right off the turbine Housing.
And the length can be 10.5 to 12" long for the 4.5" diameter piece.
Then you can neck it down to a 4" pipe and another 10" or so you can go to the 3.5" pipe.
The exhaust gasses will have cooled over that length and be more dense and will still flow properly thru the 3.5" pipe at that point. So you really do not need 4.5" pipe all the way to the firewall area. Just makes things harder to work on. Just after the 3.5" pipe transition is a good place to put your EGO Sensor to read the Air/Fuel Ratio on a "Street Car".

Tom V.

[TransAm 474]

Originally Posted by Tom Vaught

Correct. 4.5" diameter right off the turbine Housing.
And the length can be 10.5 to 12" long for the 4.5" diameter piece.
Then you can neck it down to a 4" pipe and another 10" or so you can go to the 3.5" pipe.
The exhaust gasses will have cooled over that length and be more dense and will still flow properly thru the 3.5" pipe at that point. So you really do not need 4.5" pipe all the way to the firewall area. Just makes things harder to work on. Just after the 3.5" pipe transition is a good place to put your EGO Sensor to read the Air/Fuel Ratio on a "Street Car".

Tom V.

Cool, thanks Tom.... I like that flange I posted above, but there is nowhere to mount the wastegate on it, so I may have to look into a different style. Its probably the best to mount the wastegate right at the flange to huh? It can't be mounted in just one of the pipes that go into it, be best in the flange so it can control both pipes I suppose?

[70 bird]

Here is a link to a build thread I did 12 years ago .... http://www.pontiaczone.com/forum/sho...ght=s400+build

On a side note, I just finished installing my s488 today I started it with no leaks. I could not test drive it because the weather still sucks here.

[TransAm 474]

Originally Posted by 70 bird

Here is a link to a build thread I did 12 years ago .... http://www.pontiaczone.com/forum/sho...ght=s400+build

On a side note, I just finished installing my s488 today I started it with no leaks. I could not test drive it because the weather still sucks here.

Awesome, nice setup 70Bird, I have read a bunch about yours... Which S488 did you go with? Is it the SX or SXE?

[70 bird]

I went with the sx https://www.ebay.com/itm/Borgwarner-...0AAOSwDNdViwhh

[TransAm 474]

Originally Posted by 70 bird

I went with the sx https://www.ebay.com/itm/Borgwarner-...0AAOSwDNdViwhh

Nice! Thanks for the link to your build, it's a great read with lots of good pictures

[TransAm 474]

Ok, if I want to do the crossover in 2 1/4", and keep it a true divided system all the way into the turbo, then I will likely have to run 2 wastegates, one in each pipe, correct?

[Tom Vaught]

If you have a smaller dual turbocharger set-up then you can run a small wastegate for each bank because the mass flow thru the engine is divided in half.

In your case you have a large turbocharger and probably a 455 cid sized engine so the exhaust mass flow for the engine is going to one turbocharger. With the divided inlet for the Turbine and two waste-gates the engine thinks it is two 4 cylinder engines.

If you can find a Large Waste-Gate for the installation (Precision Turbo Wastegate)

https://www.maperformance.com/produc...waAjZDEALw_wcB

You MIGHT be able to bleed off enough exhaust volume on the engine to keep the Turbo in the 10 psi boost range. A lot of variables here. 10 psi says you are not working the turbo very hard and the leakage across the turbine wheel and the compressor wheel might get you a lower boost level than you think.

But as I have said in the past, if you get a bit boost greedy then you want to flat line the pressure ratio across the compressor map and that means the waste gates have to have the ability to keep the boost line flat at that point. Otherwise you have boost creep.
The Waste gate works fine, at lower engine speeds, and then IT/They lose control of the boost at higher speeds. Two properly sized waste gates give you a lot of insurance on that not happening. CHEAP INSURANCE vs a Wounded Engine

I personally do not think the 10 psi Boost number is going to last long.
The higher the boost level the less the wastegate size needs to be because more of the exhaust volume is going to drive the Turbine Wheel.

You can even add a PWM controller to "TRICK' the wastegate into delaying the amount of exhaust volume bled off from driving the Turbine Wheel. A 1.32 A/R turbine housing is going to delay the early boost point too, vs a smaller housing. Smaller = earlier boost.

Tom V.