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chris79
Joined: 29 Jan 2014
Posts: 551
Location: milan
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 Posted: Tue Jul 21, 2015 4:35 am Post subject: performance improvements |
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I read in a post that with carbs, big valves, cam it's possible to make about 145hp.
But in a recent post I read that a user think to reach maximum 150 hp with complete tuning of Engine, pistons, piston ros, cam, valves, etc
The opinion of expert users?
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Porsche 924 2.0 na 125hp (1979) euro
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Alfa Romeo Spider "Duetto" 1.6 104hp (1986) euro |
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morghen
Joined: 21 Jan 2005
Posts: 8880
Location: Romania
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| Posted: Tue Jul 21, 2015 7:20 am Post subject: |
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dont put carbs !!
Buy a spare engine with good pistons and crank, calculate how much you have to mill from the block to get 13:1 compression ratio, take it to a machine shop, let them mill the block.
Install that engine in your car. Use only Shell 100 fuel, easy 150hp.
While you have the engine off, also take the flywheel to the machine shop to have it lightened...install in new 150hp engine for nice rev up.
Get more money, buy a hot street cam...get another 7-8hp at top end and more mid range torque.
get more money for a free flow exhaust, get another 2-3 hp from there.
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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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| Posted: Tue Jul 21, 2015 8:29 am Post subject: |
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http://www.924board.org/viewtopic.php?t=25795
Avoid carbs. Read the article "Bolt-on Bonanza" and realize that the carbs did nothing to the power delivery and only really made noise and cleaned up the engine bay slightly. The only power gain was in cylinder head work.
Rebuild the motor with pistons that provide slightly more compression than stock. These are usually custom forgings from companies like J&E Pistons.
and/or have the crankshaft welded and offset ground to increase the stroke. This would require a machine shop skilled in this type of work.
Then, properly port the intake and exhaust ports in the cylinder head with attention paid to the areas behind the valve faces and seats. Larger valves may or may not help, but aftermarket valve might be lighterweight and can help with operations at higher RPMs.
A slightly more aggressive camshaft can help improve power in certain areas of the rev range, but almost always at the expense of another area.
You've been led to the water yet again. We'd like you to take a drink and remember that you've had a drink. Eventually we'll stop showing you the way to the water and let you die of thirst or find the water on your own. Your choice.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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SlayerSST
Joined: 21 Sep 2010
Posts: 212
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| Posted: Tue Jul 21, 2015 11:16 am Post subject: |
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I think it would better serve the OP if he posted his budget on this car. Its frivolous if you guys are offering solutions that the OP cant afford or not willing to pay for.
Just saying.  |
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chris79
Joined: 29 Jan 2014
Posts: 551
Location: milan
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| Posted: Wed Jul 22, 2015 2:12 am Post subject: |
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Yes there are some false informations, 10hp only with carbs and similar, if I make some changes on my 924 I would like do all by myself, because mechanics are only thief, a tuning of engine can require easy double of cost of car.
If possible when I have necessary location, I would like buy pistons, rod and valves and start work, but budget must be maximum 1000 euro for engine and 1000 euro for asset.
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Porsche 924 2.0 na 125hp (1979) euro
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Alfa Romeo Spider "Duetto" 1.6 104hp (1986) euro |
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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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chris79
Joined: 29 Jan 2014
Posts: 551
Location: milan
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| Posted: Wed Jul 22, 2015 3:48 am Post subject: |
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1000 euro only for head work? Too much, I would like tune 924 for road and 1000 euro is maximum budget, over 1000 euro for engine I buy more performance car.
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Porsche 924 2.0 na 125hp (1979) euro
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Alfa Romeo Spider "Duetto" 1.6 104hp (1986) euro |
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Wed Jul 22, 2015 3:54 am Post subject: |
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| chris79 wrote: | | 1000 euro only for head work? |
Yep, and even that is low. Big valve upgrade is easily USD$2K by the time you buy the parts and get all of the work done. $1K will get you a valve job, porting, skimming, and not much more.
The head is the main restriction to more power on this platform. There is no point spending any money on any other modifications unless you intend to address the shortcomings in the head.
| chris79 wrote: | | over 1000 euro for engine I buy more performance car |
This attitude is exactly why you don't see very many high performance NA cars. It just doesn't make financial sense. If you're trying to make the decision based on logic, then you have already arrived at the right decision: buy another car.
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erstwhile owner of just about every 924 variant ever made |
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chris79
Joined: 29 Jan 2014
Posts: 551
Location: milan
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| Posted: Wed Jul 22, 2015 4:47 am Post subject: |
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If I have not money problem, 924 na tuned and without turbo is a dream and I would like do this project, but with my low budget there is not logic to expend 5k $ on this tuning when a 944 standard have more performance.
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Porsche 924 2.0 na 125hp (1979) euro
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Alfa Romeo Spider "Duetto" 1.6 104hp (1986) euro |
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Wed Jul 22, 2015 5:13 am Post subject: |
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I understand and agree completely. You should just enjoy your car for what it is, or accept that you can't afford to make it the dream car you want, and trade up for a 944 or 924S.
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erstwhile owner of just about every 924 variant ever made |
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chris79
Joined: 29 Jan 2014
Posts: 551
Location: milan
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| Posted: Wed Jul 22, 2015 5:41 am Post subject: |
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Yes, sometimes I find some 944S on internet for about 6k euro but 924 lines are better and I won't sell my car 
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Porsche 924 2.0 na 125hp (1979) euro
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Alfa Romeo Spider "Duetto" 1.6 104hp (1986) euro |
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gegge
Joined: 27 Jul 2007
Posts: 1124
Location: Sweden
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| Posted: Wed Jul 22, 2015 6:51 am Post subject: |
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This is a molding of the 924 inlet duct. Adress the areas in the green ovals with a DREMEL or similar device. Just make them smooth, especially the short radius down to the valveseat. It is a DIY job. The best hp/cost ratio you can get! An easy 10-15% increase in flow and output.
A 3-angle valveseat job is recomended as well. A larger exhaust from a 944 is an improvement at this level. Next step is a 268 cam. Increasing CR has diminishing returns at 9,3:1 but the dynamic compresion does fall with higher duration so skimming the deck is also a good idea at this point.
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Carl Fredrik Torkildsen
924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs |
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nickthompson
Joined: 26 Mar 2013
Posts: 873
Location: Central Georgia
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| Posted: Wed Jul 22, 2015 9:15 am Post subject: |
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| The 2.0 really isn't a good platform for a performance engine. It's has a long list of flaws including a poor flowing head. Although I've never weighed them myself but I'm sure the pistons weigh a ton. They are huge. Just all adds up to an engine that's not really good for performance. |
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leadfoot
Joined: 11 Dec 2002
Posts: 2222
Location: gOLD cOAST Australia
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| Posted: Wed Jul 22, 2015 11:31 am Post subject: |
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budget turbo conversion
$250 on welder/short course migging
$300 on turbo/internal wastegate,
$250 make your own manifold/downpipe
$200 5th injector controller/injectors and flexible line
$50 intercooler
$350 left over for smeg
taps / bolts
silicon joins / tube
gauges
hoses
run 6psi
make extra 40/50 hp... done
stock driveline
stock clutch
stock intake and head
stock tranny
stock throttle body
stock pistons
force feed the engine air and it will make power
look for used parts in serviceable condition
learn to mig weld steel
keep it simple!! and follow the path already made by other people
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress... |
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morghen
Joined: 21 Jan 2005
Posts: 8880
Location: Romania
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| Posted: Wed Jul 22, 2015 5:05 pm Post subject: |
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| nickthompson wrote: | | The 2.0 really isn't a good platform for a performance engine. It's has a long list of flaws including a poor flowing head. Although I've never weighed them myself but I'm sure the pistons weigh a ton. They are huge. Just all adds up to an engine that's not really good for performance. |
Could you post up that long list please? I'm curious what is it that makes this engine so bad.
I mean, my red 2L is surely pushing over 250hp and i have just intercooled it and strapped a K27 to it, members here have pushed 300HP out of the NA engine and they have not touched anything.
The NA pistons are quite good actually.
I think the bad flowing head story has been farted over and over and proven wrong enough times now. For what we call power and enjoyment even the NA head will flow just fine. Internals will hold and last enough for our fast street applications. Nobody here wants a 10 second 1/4 mile car. I think most of us would be happy with 200-250hp in these cars as its enough to have propper fun.
I say, either keep it a NA, but dont waste your time on head flow as its pointless for your goals. Cut that block and increase the CR if you want more power, get a hot cam and lighten the flywheel and you will love the engine.
or, a very good option has been given by leadfoot...low boost will feel great on a 125hp NA.
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