Patrick's Twin Turbo 350 Build Thread

This will be a twin setup. Thanks, I'll see if I can look into the GN routing!

This is very helpful, thanks! It's damn tight in there

 

Yep it's Frickn tight alright......

 

Good news and bad news!

Good news:

I did a proper mock up and the turbo manifold and wastegate fit the driver's side! You may remember if you've been following since the very beginning that I could not get this to fit when I tried to mock it up with the original engine in the car. I'm pretty sure this was due to worn, sagging motor mounts, which was causing interference between the manifold and steering shaft. It's still very tight down there, but it does fit. Also note that since my transmission crossmember is not installed yet, the engine will hopefully move laterally to increase this clearance once centered.







Now the bad news:

The turbo is about 1.5" away from fitting on the manifold because it runs into the master cylinder! The 4 options I've come up with are:

-Modify the brake system
-Modify the turbo manifold
-Make a new turbo manifold
-Modify the turbo mount location by fabbing an adapter







It seems that I need about 4" of space minimum behind the booster for the downpipe (3.5" for the tightest 2.125" CLR 90 degree 2.5" OD exhaust bend I could find, plus 1/2" for a flange). And right now I have -1.5, so for option #1 I need to somehow shift the brakes back by 5.5". My booster is 5.25" long, and the shortest 7" single diaphragm booster is 3.5" long. That would only shorten the assembly by 1.75" (not enough). If I got rid of the booster and went manual brakes (subtracting 5.25", I would still have 1/4" of clearance issue. I bet the Wilwood master cylinder is a bit longer than a GM one.

Option #2 is something I want to avoid for now since Mark Burton doesn't appear to be making these manifolds anymore and they seem to be almost impossible to find.

Option #3, while probably the best solution will probably take the most time, money, and effort so I'm going to move along to:

Option #4, I don't know how badly creating the adapter I'm envisioning will affect turbo performance, but here's a rough idea of what I'm thinking for turbo placement:

 

too much thinking for me

 

Seems turbo manifold needs revamping to fit with power brakes, Does #455 have different manifolds on his than yours?
They seem to fit with power booster in pics. Different turbos maybe?

 

After studying the pictures for a bit, it seem that the manifold he's using are the earlier(?) versions due to the square tubing going to the turbine as opposed to the round for mine, however I bet the positioning is pretty similar. I think the difference is not only the length of his master/booster combo but also the angle of his mounting brackets. I was having problems a few pages ago with my master being angled up too much and running into the hood, again due to my long combo of parts. If I shortened my combo up I imagine I could put the angled brackets back on and fit, so maybe I'll try this first!

 

Looking at your pics of the 4 bolt flange for the turbo, can you move the turbo forward an inch or two? Of course you’ll have to move your mounting flange forward also.
Actually this is the fun part of Hot Rodding, figuring stuff out.
If you were a Chevy guy, I’m sure Dollar General would have what you need
Us Buick guys gotta figure stuff out

 

Do you mean cut and reweld the flange on the manifold forward? I'm trying to avoid modifying the manifolds unless I need to as a last resort!

 

OOOOR, just get rid of the braking system, downshift, when you get slow enough slam ‘er into park

 

The turbo system will have to be moved somehow the brakes are important and they look too nice

 

Well I ordered a 7" single booster and angled brackets and will test the fit and report back!

 

I'm gonna play the bad cop here,...man those manifolds are just a bad idea

 

No worries, I appreciate all feedback (even if I choose to ignore it sometimes )

You think I should build tubular ones instead?

 

There is PLENTY of room in that engine bay to bring the turbo to the front,...the wastegate orientation is terrible as is,..

Do this right,..not right now,...

First power brakes on a turbo car are a pain in the dick,...go manual brakes be done with that issue,.. ESPECIALLY with those small diaphragm boosters,...not gonna be happy with that period

Cut that flange off,..weld a Vband on then run a new 90° pipe with the flange to the front and go from there,..but honestly I know you're this far and everything but that manifold with those welds.... Isn't gonna hold up

 

To be even more honest,....I would use stock manifolds and run the turbos down low ,...use a pump to push the oil back,...they work just fine,..STS been doing it for YEARS,...I had one on twin turbo Camaro

Doesn't have the look I guess,..but it solves 46 other problems and will work a **** ton better

 

Those plug wires are gonna cook,..there is NO SERVICEABILITY TO setup what so ever,....hell you can get plugs,..pull the valve cover,...can you even get to damn dipstick

 

Interesting ideas and notes, we'll see where this takes me. I at least want to give these manifolds a shot since I already have them, but long term I'd love to buy one of the overpriced ICE header building kits and go to town designing a perfect 350 Buick turbo manifold . . .

All of this is a bit premature though as my plan it still to get the car on the road with a carb, then go EFI, THEN go turbo. So maybe in that space I'll have time to come up with a better system.

 

With the way the Buick head is angled and how low the engine sits in stock configuration the turbo manifolds Burton done were a mistake from the get go,...the engine needs to be raised and the cross member modified to do a front mount turbo setup correctly on these cars,..I've done looked at it years ago,..goin up isn't a viable option,..and the reasons what are many

 

The best way to turbo one of these things with the 350 is to simply copy the 3.8 setup,..stock manifold on driver side,.. crossover,..log manifold on pass side with turbo mounted over towards the battery area

No heat issues,...no clearance issues,... single turbo will actually outperform twins especially those ebay units,...will be more professional looking,...seal better with less places to leak,... exponentially easier to service,....the list goes on,...I'm just trying to save you a mountain of headaches,...

 

That’s what I keep saying, just mimick what Buick did on the 3.8 Turbo.
Go single turbo, you’ll have all eight cylinders spooling the turbo instead of four
Twin turbos in my mind are for looks