924Board.org

[rockhound72]

Money is a little tight these days, so I try to be cost conscious. I was wondering if anyone has ever had their stock 2.0 4cyl bored out to get more horses. I had an old '65 mustang I rebuilt, and it wasn't much of an issue boring out the old straight six and giving it the power of a 300. If I go with the turbo, there is a TON of things to change out, and can get pretty expensive.

[fiat22turbo]

This --> http://www.924board.org/viewtopic.php?t=25795

might help.

Overbore won't gain you much. Higher compression (at least to the Euro levels) will help get it to 125hp from a little under a hundred.

You can add stroke to bring the capacity up a bit.

Either way, head needs some attention to fill the cylinders more efficiently. Spend your money on the head and a good ignition curve first, then build a stroked/bored bottom end (forged pistons and rods are available to help with that) when you get some more money saved up.

Another option is to swap in an Audi 20-valve 5-cylinder (base for the Audi Killer B motors, heh). There is one or two running around Europe with 170hp out of the box. Requires a modified oil pan, custom header, EFI swap and a few other bits and pieces.
_________________
Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[Raceboy]

It is cheaper to put a turbo+efi to stock 924 motor than to buy forged pistons, h-beam rods, headwork etc. Staying NA but doing all the mods will hardly get you ~140-150 hp at best (CIS is also major restrictor here), with turbo, you can easily get 230-240+ and you have a stock engine, when something blows, just buy a good used part and you're good to go.
There is a difference in goals: one is to build and fabricate per see, other is to drive the hell out of it and have fun. Your choice.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[rockhound72]

I have looked at the turbo option, but if I am correct, there are a lot of things engine wise that need to be changed out as well. Am I wrong?

[Raceboy]

You don't have to change anything in the engine. But you need to get rid of the CIS injection and convert it to EFI.

Engine needs to be just in good working order.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[ideola]

[Raceboy]

Dan, what do you mean by reliable??

My turbocharged euro 924 is bone stock and it has run constantly since March 2007 starting with ~210 rwhp and now nearly 240 rwhp. NO ENGINE FAILURES!

It ran two years without opening the engine (engine was original, from 1983 car) and I only refreshed it when I put it onto my red car and that was purely "while you're in there" manner, not a necessity.

I have always stressed it out that it is the tune that matters as with any engine. US engines are even easier as they have less CR compared to euro engine 9.3:1 which I have.

EFI without turbocharging yields driveability, better fuel mileage and better starting + some hp.

The turbo kit together with full EFI conversion is soon available from my car as I will most likely be parting it out.

The cheapest option to get big hp out of 924 engine is like the factory did it: turbocharging it. But time has passed and there are MUCH better approaches to it than using original expensive and unreliable parts.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[fiat22turbo]

Well, as someone who sells new parts and a bit of a perfectionist, he's a bit biased to one extreme when it comes to building and tuning these cars. Not that his approach is wrong, it just may not be correct for all of us. Many of us bought our 924's because they were cheap and fun, so spending $1500 to double the HP on a $5-600 car is only something a true believer would do.

On my car, aside from a lot of maintenance items, my EFI system was about $1000 and most of that was the ITB's at $600. The DCOE intake was $130. The MegaSquirt ECU was $120, the EDIS trigger wheel was $60, the rest was wiring, used injectors (taken from a working car), regulator, hoses and fittings.

If I were to do it again using the stock intake and TB, it would be at least $600 cheaper and much easier to start out the build on and begin tuning with. Using more OEM components will keep the cost down without a negative impact to reliability.

The learning curve on MegaSquirt is quite high for the first timer, especially one dealing with dyslexia and ADHD (me, unfortunately). Thank goodness for the help here and on the MegaSquirt forums, or I'd still be fighting with the tuning.
_________________
Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[Raceboy]

My point was to show that there are ways to do it and NOT spend a small fortune on it.
It is weird that people buy 1000+usd GT intercoolers but consider 1500usd turbo setup expensive.
I have yet to see a street-legal 931 other than Joakims car that is faster than my nearly 300hp 924 but still people don't consider it a proven thing, both in performance and reliability?
I'm beginning to think that this board really doesn't need my input on how to make these cars faster as everyone seems to know it perfectly well themselves: just spend a bunch of money and not focus on things that truly matters.

These statements do not apply to you Stefan, you have done a great job on your car and not hesitate to learn new things.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[Rasta Monsta]

[ideola]

[rockhound72]

Well, I can honestly say that I have had more input than I was expecting. It appears to me that for true performance, it will take $$ and no slacking on parts for reliability. A fast car means nothing if it doesn't run. I hope to get a picture of my little '79 up here soon. I have it propped up replacing a cv axle and working on getting to that @#$$ shifter bushing on that snailshell. I have access to a ford 302. I wish I could drop that in there. haha. I appreciate all the input very much. Expense- wise, I want to start off easy to keep the wife from having a heart attack. $500-$1000. The car is a blast to drive, I just want a little more umph when that jack @#$ pulls up in his kit car wannabe, and leave him behind. For now, I'll just wave as they pass.

[Khal]

Mate, no. Just no.

You picked the wrong car. No big deal, offload it and be done.

Everyone that's replied to you here has serious in-depth knowledge. Trust them.

And Raceboy is on to a good thing, I reckon. I've mentioned it before.

But check out his list of cars, rockhound72. It's not an insult but I'd be willing to bet that to him, US$500 (What? €390?) is not a huge amount of money to drop on upgrades. I doubt it'd pay for one decent part, in fact.

I paid US$300 for, quite literally, the cheapest set of tyres I could find. And that's in Oregon, with no sales tax! Just a set of cheap rubber, mate... a third of the top end of your budget...

Nah, wrong choice. The toofah has the badge and can be had next to free. But decent performance mod's cost no less than any other car. Sorry
_________________
'80 924 Turbo

[CorsePerVita]

Yeah I can imagine with high compression pistons, or a stroker build of some sort, head work and a nice ITB setup you could pull 150+ but pulling tons on an N/A would be an expensive feat.

Turbo or Supercharged would likely yield more power but no matter how you slice the pie, you aren't going to get around any way to make that kind of power without spending money.

I've put a good bit of money into my engine rebuild, my parts, my megasquirt, tuning software and everything I've needed to do things the way I want it and at first I imagined it as a "cheap build" and it didn't turn out that way.

To be honest, I'm fine with that, and I'm happy with things and I'm happy it's turning out the way I want it. I can't wait to get it tuned enough to really get an idea of what it'll feel like before and after but I'm STILL not there, but I'm close. Either way, I plan on eventually supercharging it once I get my N/A working properly since the euro setup should be "low enough" to do a low psi supercharger setup.

If you do enough weight reduction though, your horsepower to weight ratio can help. But then you get into that slippery slope between "practical" and "race car" - If you want, you can make it light, strip things out, use different materials and shave tons of weight off. Or... you can try and get lots of horsepower on a car with full interior and parts.

I can tell you though that the weight reduction I got from going from CIS to ITB megasquirt was awesome. With carbon fiber intake runners, my ITBs and even my rail, under the engine bay it was a total of 7lbs. Compared to the 40+ whatever it was with CIS. Every bit counts.

On top of that, the money into building my brakes, refinishing things, fixing things the way I want them, and fixing little things as I go, and changing things to the way I want them from things I saw I didn't like prior... that takes time and money also.
_________________
- 1977 Porsche 924 2.0 N/A (Trackday Project)
- 1979 Porsche 924 2.0 N/A (The other daily)
- 1980 Porsche 931 (Daily)
- 1987 Lamborghini Jalpa
- 1999 Ducati 900SS

[Raceboy]

Turbocharging (turbo, modded 951 cooler etc, piping)+ efi (including VEMS unit, injectors etc) were ~2500 euros. I did the work myself.

Next thing was the clutch as brand new NA unit could not cope long with the power without slipping and I bought Spec Stage 3. But cheaper option would be to use BMW E30 215mm pressure plate (Sachs Race Engineering version) and sintered disc. I just got the Spec clutch locally for a reasonable money (~300 euros).

Reliability came from tuning and as I have experience both with (perfectly working) CIS and EFI, to be honest, there is no contest.