928 bolt on question

Hoang928 · 12-24-2008, 02:56 PM

my 1981 928 five speed is stock and im thinking about doing bolt on , where should i start at?

Danglerb · 12-24-2008, 03:08 PM

First thing to do is get it running stock at 100%. Anything done away from stock will make sorting out problems more difficult. Once it is running great, easy step is to upgrade the exhaust with 85/86 manifolds a Y pipe and high flow cats and mufflers.

More power and next step would be a Euro S motor, or Euro hybrid, unless you want to give a turbo or blower a try, but I see those as more work and less reliable.

Other way to go is to start taking out weight, 300 to 400 lbs removes most of the niceties, but its like adding 40 hp.

Hoang928 · 03-09-2009, 04:33 AM

what do you mean by euro bybrid

Normy · 03-09-2009, 05:24 AM

"Euro hybrid" means taking a US block and mounting pistons, heads, cams, and complete intake manifold from one of the ROW or "rest of world" 2-valve 928 engines.

US model: 234 hp

ROW model: 310 hp

Which means adding 32% more power just by changing stock Porsche parts for....stock Porsche parts. That is, if you can find them.

Easiest way to identify an ROW engine? Twin distributors. The '84-'86 ROW cars used the ignition system designed by Bosch for the '85-'86 32 valve cars. NO vacuum or centrifugal advance at the distributor- it was done electronically. Since the 32 valve cars had two distributors, so did the '84-'86 ROW cars. Two 944 distributors linked together with a tiny toothed belt.

-It's a BIG expensive job to convert to a "Euro hybrid"; either remove weight, add a blower, or simply sell your car and buy a faster 928.

N!

Normy · 03-09-2009, 05:27 AM

M28-21 engine in my own '85 928S2..

N!

Roy928tt · 03-09-2009, 04:20 PM

I thought the question was "bolt on", a hybrid is hardly a "bolt on". I'm thinking the only real "bolt on" solution is a centrifugal supercharger insallation they seem quite popular and easy. Some sort of forced induction is the way to go, you can change cams and induction, exhaust and compression but nothing matches the power of forced induction.

MPDano · MPDano's Garage

Yeah! Sc it!

Normy · 03-09-2009, 04:53 PM

You can spend $7000 buying an S2 head, cams, and pistons and intake, or even a kit with the whole mentioned before along with the electronics...

-Or you can just buy a whole 928S2 for the same price!

Sure, it won't run well, but that's your problem. If you spend several thousand hours online researching your car you can build something pretty good from a trashed S2. And it will happily show an S4 or a GT or a GTS its' recessed tail-lights up to about 125 mph.

S2's...also known as "Euro '84-'86 cars" are the wild-child of the 928 world. If it runs right, it will leave anything up to a C5 corvette. If it doesn't, it will act like it has 100 hp less and will eat gas like a Ford Excursion. Ask me how I know this...

The S2 cars are for people like me who are committed to this car, and dont mind spending the time under the hood making the thing work. If you aren't this way, then I would tell you to ditch your car and buy a GT, or if you have a bunch of extra money for an inch of metal...then a GTS.

N!

lizard928s · 03-09-2009, 04:57 PM

the only people who do SC kits for your year is 928motorsports.

do the exhaust first (stock manifolds), either an x pipe and dual pipes, or a y and signle pipe.

Then boost.

Those are the only bolt ons.

rhjames · rhjames's Garage

as he was not specific as to whether his is a Euro/ROW or a US spec '81, it will make a difference as to what you recommend, particularly when it comes to injection.

a hybrid is not quite just using a US block and going from there.

you would use a 85/86 5.0 block, cut the piston tops for 16V valve reliefs, and use the 16V Euro/ROW top end parts ( heads, cams, intake, lower intake, throttle body). 85/86 exhaust manifolds would be an added bonus.

it is not necessary to change the ignition or injection parts for this conversion.

Otherwise, just add a blower of some sort.

--Russ

m21sniper · 10:11 PM

Quote:

Originally Posted by Hoang928

my 1981 928 five speed is stock and im thinking about doing bolt on , where should i start at?

Exhaust makes the biggest immediate difference- 30+ HP easily, and can also totally transform your cars sound into that of a wild beast.

Click the link in my sig and turn your volume up.

The next easiest way, and by far the cheapest, is to put your car on a diet. You can shave as much as 600lbs from a 928 if you work hard at it. That's the equivelant of adding about 75-80 horsepower, plus you also get better handling and braking as a result as well.