262's 85 Fiero SE LX9 F23 swap thread lots of pics

[TGP37]

I was almost thinking about mounting it under the turbo, but I would prefer easier access than that...

I had mine angled down a while back. When servicing I found residue build up from oil or gas (or water condensation) and caked from the heat on the diaphragm. Which seemed to break down the diaphragm (though I thought the diaphragm material should hold up to hydrocarbons, voc's etc)

Now I am mounting it upright. Once I get a better quality replacement.


On that note, I believe a good quality WG could hold up being upside down. But I wouldn't unless it was absolutely necessary.

You could get two mini WG's and attach each one at the end of each manifold. Dual WG might help reduce boost creep. If space is hard to find, there is always room near the manifolds on the sides. It is the center line of the block where room is limited, right where you want a single wastegate to be.

I want mine just ahead of the turbo but that isn't happening. Intake and throttle are in the way.

Tial mini compared

[ericjon262]

it wouldn't be upside down, it would be level with the ground, not that that would change anything though. thanks for the pic of the Tial products, I didn't realize they made a gate with that low of a profile.

[TGP37]

Only thing about the minis is valve lift. Don't want to out flow the wg or it will lead to boost spikes.

Always make sure the wg can flow what your pushing.

[ericjon262]

I was thinking about a 44mm Tial MVR, think that would suffice?

[TGP37]

I can not say for sure. I know I had used a 38mm external with no issues up to 12 psi. But I am also running 3100 @ 12psi and your 3500 at ?psi.

I believe it is better to have a slightly larger WG then one that is too small. If you are out flowing the WG, turning the boost down would be an option.

38mm CS is 119.4 mm2
44mm CS is 138.2 mm2



I remember you mentioning you want a twin scroll turbo eventually. If this is the case you really might want to consider/look into a dual WG setup to take advantage of waste gating both sides evenly.

In that case, if it is feasible, you will have excellent flow and I see no reason for any boost creep.

If you decide upon an electronic boost controller, the boost control would be strong and accurate.


Some say dumping the wg to the atmosphere is better, some say it causes boost spikes at onset. I really never got a straight answer to that yet. But to be a DD I decided to dump into the DP before the catalytic.



After reading this, I am considering dual WG. LINK

A wastegate wants to stay shut because there is a spring pushing on the valve. When the turbo builds boost, it also builds backpressure on the other side of the gate valve. The greater the surface area of the valve, the more total pressure the PSI can create to push against the spring. This is why a wastegate will eventually open even without a control hose attached to actuate the diaphragm.

Now, you need a minimum surface area of wastegate valve to flow enough gas to actually control the speed of the turbocharger. If you split that surface area between multiple gates, you can make each smaller so there is less pressure pushing on each spring per PSI of backpressure. You can then install lighter springs that will actuate with less boost (lower minimum boost) and stay shut to a higher backpressure (higher max boost).

[robertisaar]

If you are out flowing the WG, turning the boost down would be an option.

perhaps i'm thinking about this wrong, but if the wastegate is too small, won't turning down the desired boost cause more boost spike/creep issues since now it needs to bypass even more exhaust gasses?

[ericjon262]

I would like to do twin gates, but I don' think I'll be able to package them in the space allotted.

[ericjon262]

perhaps i'm thinking about this wrong, but if the wastegate is too small, won't turning down the desired boost cause more boost spike/creep issues since now it needs to bypass even more exhaust gasses?

there should be less gas flow at lower boost levels, so if you limit the boost before it outflows the gate, it might work.

[TGP37]

perhaps i'm thinking about this wrong, but if the wastegate is too small, won't turning down the desired boost cause more boost spike/creep issues since now it needs to bypass even more exhaust gasses?

Lets see if I got this right....haha

As the hotside pressure reaches 14.7 psig, peak velocity of gas traveling by the valve is reached, sonic speed limit.

I believe, IIRC, a pressure gradient of 2/1 between two atmospheres of gas, etc, sonic velocity speeds occur.

Once boost in the hotside reaches 14.7 psig the size of the wastegate dictates how much will flow (aside from dp back pressure and all the minor variables) by cross section.

Pulling the boost back reduces the back pressure across the wg valve. Preventing less diversion to the turbine. Which, the diversion, makes more boost increasing the problem.

I believe the flow between the turbine and the wg is volumetrically proportional to the exhaust flow overall, considering the CS of the turbine and the WG.

I would like to do twin gates, but I don' think I'll be able to package them in the space allotted.

Yeah, Fiero....an honorable challenge to pack all that in there.

One big fat one should work well enough. Any boost controllers in mind?

Turbonetics lists how much hp theirs will support.




Ah, engineering. much fun, much fun.

[ericjon262]

A little more progress one the hotside today.

[3400-95-Modified]

There is a huge hole in your intake if you didn't notice... it might cause a boost leak... Almost perfect to bolt a SC to... LOL

[pocket-rocket]

Twin charging time, like that crazy Lotus

[ericjon262]

the hole is for a 2.8L Kenne Bell on craigslist that I'm picking up on sunday.

[TGP37]

the hole is for a 2.8L Kenne Bell on craigslist that I'm picking up on sunday.

For real?!

Hmmm, a dual throttle body or you gonna plug up the stock neck?

In series, 8 psi turbo + 8 psi SC doesn't = 16 psi. It is more like 20 psi....but parallel SC and Turbo is really interesting. You going to use the SC to spool low and the turbo spool high?

[ericjon262]

For real?!

Hmmm, a dual throttle body or you gonna plug up the stock neck?

In series, 8 psi turbo + 8 psi SC doesn't = 16 psi. It is more like 20 psi....but parallel SC and Turbo is really interesting. You going to use the SC to spool low and the turbo spool high?

LOL, I wish! I was wondering how long a reaction would take!