Let me add my HOLY S**T to the pile! I took it for a ride tonight with the supercharger installed for the first time and HOLY S**T it's amazing what 4-5 pounds of boost does for a 4.7L 2 valve motor!

We finished the install and started it up. It fired right up and idled nice. Let it warm a bit, then reved it a few times, and noticed the rubber boot from the throttle body to the SC piping swelling up like a frog's throat each time I revved it. Some duct tape with an outer layer of metal tape solved that temporarily, we'll have to come up with something a lot stiffer for that piece though.

Took it out on the road and it was well mannered when driving slow and took off like it's tail was on fire when I stepped on it. Stephen said he saw just under 5 lbs of boost at one point, I was much too busy looking at the road :-) . Wow

Bill
'84 s 5 sp/Vortech (FrankenPorsche)

 

Well, well, well. Congratulations.

You guys are having way too much fun. Stop it, before I have to join in, damnit!

As much as I though it would be cool to replace the spider with a twin screw, it looks like that was a very easy intallation.

Would you be willing to divulge what it cost you? And what you did to the fuel system? I should know better, but I've not been paying much attention to the details in the sc posts.

Gregg

 

BShaw,
Conrgatulations on getting it on the road quickly and successfully. It truly is amazing what even a few PSI of pressure can do for these cars. About the pipe swelling up, I don't see a blow off valve in your picture. Maybe a blow off valve would help relieve some of the pressure? Seems to me that you would definately need one or else durring rapid closing of the throttle you chance popping a hose off.



Gregg,
My system for the 16V cars retains the intake runners for the spider.

Andy K

 

Congrats Bill - looks great! Is the plenum backwards? Why?

 

No doubt, you absolutely need one.

While under boost, what was your air/fuel ratio? What are you using to measure it?

 

Well under $2K so far. The fuel system is stock, but I'll need to do something with it before I add much more boost.

 

Blow off valve is still on the bench. One more thing I need to see to before I increase the boost.

BTW, I love the twin screw setup you're working on. Maybe on my next SC 928....

 

The plenum is backwards to let me mount the LT1 throttle body. I didn't have room for it to stick out the front.
http://mywebpages.comcast.net/p-928/749.html

 

Yep, the blowoff valve is going in soon. Probably before the intercooler. Under boost I was seeing 2 yellow bars above green - about 7 bars out of 10 on the AFR guage. I'm using a 10 LED afr guage hooked to the switching O2 sensor. I have a wide band that's going in soon (one MORE project!) that reports the AFR in the 749's ALDL data stream.

 

Blow off valve is still on the bench. One more thing I need to see to before I increase the boost.

BTW, I love the twin screw setup you're working on. Maybe on my next SC 928....

 

16V twin screw with the "spider" intact ??!!
That, i cant wait to see. Very interesting.

 

bshaw..........you gonna hurt that engine without a blowoff valve........finish the job before you go beatin on it any more.......

congrats, the install looks nice with the original spyder. "May the boost be with you"



BTW, show us your bracket.......................

 

That is too lean under boost! That's approx a 13+ air/fuel ratio. I would keep my foot out of it until you're able to richen it up. You want solid green with maybe a flicker of one yellow every now and then.

I would install the WBO2 sensor first and the blow-off valve at the same time, and take it from there.

 

Why would it be too lean? It's well on the rich side of stoich.

I'm not too worried about the blow off valve at the low boost levels I'm running, Corkey Bell in 'Supercharged' says it'll help cut down on noise but isn't as necessary with low boost levels in a supercharged system as it is in a turbocharged system. It's definately going on, but I don't think it's a critical item at this point in the game. If I was at 8 to 12 lbs of boost maybe, but not at 4 to 5 lbs.

Now blowing off a pipe when I slam the throttle shut is a possibility, but that wouldn't be a fatal problem either, just an annoyance.

Or am I totally off base here?

 

Anna one , anna two ...now for the Jingle ......One or two YEARS for a stroker ...... 12 hours for a blower ! waiting and waiting you just get broker ........ in the end you may still be slower ! (chorus ) Normally aspirated sucks ...give me boost , give me boost , give me boost . The experts said "you're gonna blow her " But you say " the car just seems slower ". They say " it just won't last " but you say " Yea , but sure is fast " ............( chorus) Normally aspirated sucks .... give me boost ...give me boost ... give me boost ... Well done Bill but you were slightly off key