justaguy

Just bought a supercharged car but Vacuum line to brake booster in not connected. Is it possible to get vacuum off a boosted engine? Or do I need an electric Vacuum pump.
Thanks
Sean

DR

NO, we all add 100-300hp to our 928s and reduce the braking...it's more fun that way!!



J/K

Something's fracked, NO excuse for what you describe. Post details and pics of your SC install and we can help you better.

jcorenman

Sean,

There is a check-valve on the vacuum line to the booster, so it gets "filled up" with vacuum on decel, when the throttle is closed and there is engine vacuum. The check-valve holds the vacuum in the booster during acceleration.

I assume it works the same with boosted engines, but DR is the man.

justaguy

Test for pics

justaguy

Heres a couple more

IcemanG17

Wicked ride!!!!! But it might make Petty jealous.... :>)

The brake booster clearly isn't right......that would make for a CRAZY heavy pedal!!!

justaguy

Ok so got the pictures posted. I have two problems 1) is no vacuum the other more pressing problem is that the car is overheating. The car has a custom water bridge that appears to be restricting the flow from the drivers side head. I measured a temp differintial of 50 DegF between the drivers side head and the fabded water bridge right at the connection between the two. Head was 220 and bridge was 170 measured on either side of the connection between the two. So obviously flow between the head and the bridge is restricted.

Dave you got a cure for this? If you have a water bridge that works with a super charged 4.7 I'll take one

Sean

justaguy

There should be Vacuum in the air box or some where on the intake side of the SC but I am preoccupied with the Overheat issue at the moment.
Please help

IcemanG17

Hmmm

Option #1: Pull all the SC stuff......get a Euro S LH intake-TB assembly + stock waterbridge from Anderson and install it....then reflash the motec to work......
Option #2: measure the angles and interior dimensions of the stock water bridge....then fabricate a better one to hopefully make the temps better? This will take a bunch of work AND may not work???
Option #3: By far the hardest......pull the good running engine out of widow + all the wiring and install that..... I don't think there is enough time for this

Given the SHORT time frame....I am liking #1 more an more.....Anderson could ship out 1st thing tomorrow overnight (pricey)....which gives you a couple days at best to get it sorted.... It should make good power even without boost.....

options are dwindling quickly.....

One last ??? did you drive it with its current tune, BEFORE it overheats? Does it run well briefly? It should be a WICKED ride....

jcorenman

Sean,

Wicked looking engine! What's the history? I've got to assume that it ran properly, without overheating, and some point in the past??

If that's the case then I would not be too quick to assume the bridge design is at fault... It must have worked at some point.

Is the thermostat OK? Rear t-stat seal OK?
Is the water pump OK? (Impeller hasn't come loose, etc).
Is there possibly a big air bubble somewhere? The stock system is (mostly) self-bleeding, but a different bridge might mess that up.
Or something plugging a passage somewhere?

BPG_Austin

Sean, sorry I don't have any technical help for you. But, this is really an interesting car! Please post some more pictures of the interior/exterior! That is some crazy Fabrication work for the SC.

Imo000

Wow, someone put some serious effort and planning in that. Looks like a one off homebrew. I like it.

DOes it overhard under load, at iddle or both?

Rob Edwards

What happened to the Widow?

DR

Hi Sean,

Thanks for the pics, that helps a lot, and as others said, a very interesting project!

The easy part first.. look on the backside of the system for the throttle body, you should be able to install a port in the "air guide" between the Throttle body and the SC Inlet for the Brake Booster.

Concerning the Coolant Crossover (bridge)...I have not seen a "custom" version of those yet that works right.. not saying there aren't any, just haven't seen or hear of one.

FYI, I do have some Coolant Crossovers that will work with a Supercharged 16V engine...and so does every one with a 16V engine (meaning a stock one :-). BUT, it obviously will not work with that system as it is now (that can be fixed).

You can modify that system pretty easily to make it work with a stock coolant bridge. Feel free to call me and I can put you on the right path for that.

In the meantime and due to so many variables in that system, if it were me I would remove the SC drive system completely. Be sure to cover the drive extension mounting surface of the SC with a cover plate (so the oil doesn't pump out).

Then I would install a stock 16V crossover and verify the coolant system integrity to see if it is caused by the modified Crossover or not. You can run the system without a drive at least enough to warm up the engine and test/verify the rest of the cooling system.

Once you know for sure the cooling issue is related to the custom crossover (or not) .. you could proceed with the best way to work around the crossover issue, again feel free to give me a call as I have 2-3 different approaches you can choose from.

As others said, it is an interesting system and it would be great if you can fill us in on some of the history.

Cheers,

Randy V

No help on the problem at hand, but I can recommend you buy some new hood shocks from DR or one of the other 928 vendors here so you can remove that broom stick.

They're relatively inexpensive.