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Porsche 931 with 15 to 20 lbs boost - how much HP?
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Rick MacLaren  
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PostPosted: Tue Aug 14, 2001 5:34 am    Post subject: Reply with quote

Actually yes, it's excellent.
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numbers  
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PostPosted: Wed Aug 15, 2001 6:21 am    Post subject: Reply with quote

Guys, I have been running 17 PSI for the last three years in my '80 with stock ignition, stock CIS, and no intercooler in 100+ degree temperature using 91 RON pump gas. I have had no detonation, and no head gasket problems. The only real negative I have to pass on, is it runs hot. To help with this I have installed an overflow bottle to catch the coolant that it pukes out after a hot run on a 100 degree day. I think a lot of people underate this little engine, and tend to pass on limits that some mechanic has told them with no real basis behind them.
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Rick MacLaren  
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PostPosted: Wed Aug 15, 2001 6:46 am    Post subject: Reply with quote

Hey it's good to see your message here.

I don't want to add an intercooler under the false belief that the engine isn't strong enough to take the pressure. But I'm still doing the alcohol and water thing just to ensure I've covered all the bases. Remember, the cost of a new head and the difficulty in finding one makes guys like me really conservative where heat is concerned.

Wanna race? Heh.
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data  
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PostPosted: Wed Aug 15, 2001 10:37 am    Post subject: Reply with quote

Hey numbers sorry to inform you, that little coolant your are pushing out, is because you are pressurizing the coolant system DUH!
SO WHEN THE GASKET FAILS COMPLETELY YOU WILL NOTICE IT MIXING WITH THE OIL. My intentions are not to tell you that 17 psi with 91 ron gasoline cannot be done , just that it is STUPID! Every increase in intake temperature is also added to the exhaust temp. and will increase your EGT. So 17 psi without an intercooler is a disaster for making power and will only fry your engine.


[ This Message was edited by: data on 2001-08-15 10:43 ]
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cs  
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PostPosted: Wed Aug 15, 2001 10:55 am    Post subject: Reply with quote

how difficult would it be to install a fuel distributor off of a 928. how would you run two lines to one injector and would the injectors have to be swapped out for higher flowing ones.
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John H  
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PostPosted: Wed Aug 15, 2001 11:56 am    Post subject: Reply with quote

Guys,
I run a Carrera Gt replica and run up to 1.1 bar boost. recently a friend and I have made and intercooler for his 931 base don my GT unit - see attached link for the cooler
http://communities.msn.co.nz/924CarreraGTInfoSite/intercoolers.msnw
If you want one let me know - it fits the original turbo mounting points and the cost is US $500 (ex New Zealand and with charge tube requried in exchange)delivery approximately 2 weeks after order on or receipt of charge tube.
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924 turbo  
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PostPosted: Wed Aug 15, 2001 2:55 pm    Post subject: Reply with quote

Quote:

On 2001-08-15 11:56, John H wrote:
Guys,
I run a Carrera Gt replica and run up to 1.1 bar boost. recently a friend and I have made and intercooler for his 931 base don my GT unit


The intercooler looks great! Any dyno tests or lap times before and after? Seat-of-the-pants dyno, perhaps? How much boost his he running?
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John H  
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PostPosted: Wed Aug 15, 2001 3:42 pm    Post subject: Reply with quote

When the GT cooler went on (prior to the custom unit) and boost went from 0.7 to 0.8 bar, the lap times dropped on the circuit we use here from about 1.24 to low 1.21's. The new I/c went on but first time on the track on of the brackets broke so I/C wasn't sitting properly allowing boost to flow past throttle body - we're back to the track on the 26th so we'll see how it goes. For those of you who race or drive a 931 hard the performance drops off after the engine gets hot, current feed back (from my friend) on the custom I/C is that it acts the same as my GT unit the power is still there even though the motor's gettign hot.
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Mark CSC  
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PostPosted: Wed Aug 15, 2001 10:27 pm    Post subject: Reply with quote

Hello Richard

Long time no argue with.
Standing start against a WRX? Not a hope in hell!
Oh and they have a bit more power than you quote have a look at http://dyno.scoobynet.co.uk/ under the MY01 section.
0-60 time range from 6 - 5.5 seconds.
A few cheap mods will add loads more power.
I know one guy who got 4.5 with only 250bhp

The way to beat him? Try a rolling start at about 50 mph. If you have more power at the wheel you should pull awy from him.
Cross country a WRX should leave most cars for dead unless the other driver is rubbish.

Good luck and let us know how you get on.

Mark
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numbers  
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PostPosted: Thu Aug 16, 2001 8:42 am    Post subject: Reply with quote

No offense data, but all cooling systems are pressurized. With a blown head gasket, you will overheat and puke anti-freeze at all tempertures, not just on 100 degree days. However, as I stated, with more boost, you will run hotter. And, as we all know, the cooling system on these cars are barely adequate for stock boost. Also, any increase in boost is going to put more strain on your engine internals, so the life span of your engine will be shortened. However, so will any modifications that will increase horsepower. So, if you want to put another 100K on your engine, you had better leave it stock. But, if you want more performance, then you will have to put up with negative effects. The purpose of my post was to give the other board members an example of what has been done, and what the effects were, so that they can decide how much risk they want to take. It seems like the purpose of your post was to call me stupid.
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larso  
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PostPosted: Thu Aug 16, 2001 2:21 pm    Post subject: Reply with quote

sometimes head gaskets can be blown partially.
I once talked to a guy that drove a car for months with a blow head gasket. It was just very minor. Then a few months later it did end up getting worse. So you may have a slightly blown head gasket, or u may just have steam bubbles or something, either way, u are going over boiling temperatures, maybe a copper head gasket and some studs would work well for u?
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Rick MacLaren  
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PostPosted: Thu Aug 30, 2001 4:32 am    Post subject: Reply with quote

Hey Mark,

The times I gave are from Turbo magazine - I trust a magazine's objectivity over a bunch of Scooby fanatics (0 to 60 in 5.5? Gimme a break). They turn 180 hp ATRW for crying out loud! I think the cars in the USA are differently rated (i.e., they are different cars due to smog controls, etc.) from the ones in the UK.

The site you gave lists dynos for the Japanese and UK model of the WRX. I was interested in these...but they are $50,000 USD, compared with $25,000 USD for the model they ship to the USA. What's the difference? The Jap model has an intercooler mounted frontwise, and the US model has the intercooler mounted on the top. Different suspensions, even pistons. No comparison.

The power at the wheel ratings of these cars totally sucks. But some impressive figures come out with mods, it's true.

It's still an ugly car regardless of how fast it rates on the dyno.

Rick

_________________
1980 Porsche 931 C2H5OH/H2O injected 15 PSI
1979 Porsche 924



[ This Message was edited by: Rick MacLaren on 2001-08-30 04:52 ]
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