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Rebirth of a Legend
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Raceboy  



Joined: 01 Mar 2004
Posts: 2322
Location: Estonia, Europe

PostPosted: Wed May 13, 2009 5:11 pm    Post subject: Reply with quote

There's no point in building 3liter turbo for racing because difference in powerband and max power between two is marginal and on the track you won't let the rpm drop out of range anyway.
But 2.5liter engines are readily available (cranks and blocks) and so are 16v S heads.

But for 2liter, custom head would be a viable option because water+oil galleries aren't needed to go thru headgasket, on proper racecars water and oil are provided from separate pipes/hoses from block to head.

Port shape and size should be copied from Porsche 16v heads as they flow BETTER (not by muvh though) than Cosworth 16v head (like Mercedes 2.3 16v). Figures are 301 cfm (Cosworth) and 310 cfm (944 S/S2 head) @ 28inches.
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
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CÚdric  



Joined: 27 Aug 2004
Posts: 2043
Location: Sweden

PostPosted: Wed May 13, 2009 5:45 pm    Post subject: Reply with quote

there are already alot of fast 3ltr turbo cars, it seems to be a better base than the 2.5 for a really fast car, better cylinder linings (are they called so?) better head design and so on.

So theoretically theres no point of building on the 2ltr plant. But "everybody else" has already gone the 2.5 or 3ltr road, there are monster track 944 turbos every where. From my pov theres much more fun to build a fast car out of the 2ltr, but its your pennys you have to spend so you choose
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bass gt  



Joined: 02 Dec 2004
Posts: 971
Location: Johannesburg for now!!

PostPosted: Wed May 13, 2009 6:05 pm    Post subject: Reply with quote

Raceboy,

I must admit, the thought of the 2 litre is really interesting. Depending on what comes from the upcoming flow bench tests, we'll see where this goes.
I've already been doing some preliminary work, and i think we could do something VERY similar to the Audi 5 cylinder 20V head. As you know, that head used a single cam wheel, with an internal drive mechanism. It might even be that the head bolt layout is similar. So i think this might be a good place to start to lay out a feasible design. Just need to see a 20V head to understand the differences.

Steve
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Raceboy  



Joined: 01 Mar 2004
Posts: 2322
Location: Estonia, Europe

PostPosted: Wed May 13, 2009 7:26 pm    Post subject: Reply with quote

CÚdric wrote:
there are already alot of fast 3ltr turbo cars, it seems to be a better base than the 2.5 for a really fast car, better cylinder linings (are they called so?) better head design and so on.

So theoretically theres no point of building on the 2ltr plant. But "everybody else" has already gone the 2.5 or 3ltr road, there are monster track 944 turbos every where. From my pov theres much more fun to build a fast car out of the 2ltr, but its your pennys you have to spend so you choose


There's always a point in building a 2litre engine because it has stronger crank and bullet-proof block.

But comparing 2.5l vs 3l. I'm not even considering 8v engines as they are waste of money and time on both because there's a ecellent 16v heads available. And 2.5liter S and S2 heads are IDENTICAL except for the bore size and one water passage. With a bit of modifying, both are usable on both blocks.
Regarding blocks. If you want tryly powerful car, both blocks are crap. You have to close the deck and with that kind of mods, it really doesn't matter what to use.
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
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ic932  



Joined: 11 Feb 2005
Posts: 1104
Location: UK

PostPosted: Wed May 13, 2009 8:43 pm    Post subject: Reply with quote

Raceboy wrote:


But comparing 2.5l vs 3l. I'm not even considering 8v engines as they are waste of money and time on both because there's a ecellent 16v heads available. And 2.5liter S and S2 heads are IDENTICAL except for the bore size and one water passage. With a bit of modifying, both are usable on both blocks.


S2 heads were also reinforced by 20mm where the cylinder head nuts sit. Might be relevant in a boosted application over a period of time?

S2 engines are probably more common and easier to get hold of. Price is about the same too. M44/40 can use 951 pistons, 944/41 will need a more expensive but easily available piston solution.
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Raceboy  



Joined: 01 Mar 2004
Posts: 2322
Location: Estonia, Europe

PostPosted: Wed May 13, 2009 9:04 pm    Post subject: Reply with quote

On a race engine it has little significance and on 944 engine, it's the block and crank that is weak (block because of the open-deck design and crank because of the dreaded oiling problem).

3.0l blocks and cranks are MUCH more expensive than entire 2.5liter engine. Not to talk about expensive custom pistons. 2.5liter engines are available all the time and it's a valid point on race-car that may need engine and can't wait another few weeks or even months.

The added (questionable) benefit on a race car is not worth IMO the added tremendous expense. On the street it's good to have very good low-end (1500rpm and up) torque but on the race-track driver has to hold the rpm in correct range anyway, otherwise the gearbox is not suitable for the application.
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
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bass gt  



Joined: 02 Dec 2004
Posts: 971
Location: Johannesburg for now!!

PostPosted: Wed May 13, 2009 9:28 pm    Post subject: Reply with quote

Raceboy,

So if you have an open choice, would you go for a custom head on the 2ltr, or build a bespoke 2.5 with existing parts where possible, and using custom rods & pistons. I know about the 944 series bearing no 2 issue, but dry sump will resolve this.
And forgive my ignorance, but what exactly is a "closed deck" Am i right in thinking it's where the block & head are seperated in terms of oil & water flow? ie no water from the block goes into the head and vice versa, & same for oil?

Steve
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morghen  



Joined: 21 Jan 2005
Posts: 8242
Location: Romania

PostPosted: Wed May 13, 2009 11:03 pm    Post subject: Reply with quote

the 944 open deck problem could be fixed with something like this:

http://www.honda-performance.com/info-lv2.asp?id=346

does this work?
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Raceboy  



Joined: 01 Mar 2004
Posts: 2322
Location: Estonia, Europe

PostPosted: Thu May 14, 2009 4:22 pm    Post subject: Reply with quote

Steve, I think on a race-car I'd go for 2liter engine because of the strength of it. But on the street car, I'd go for nice 2.5 or 3.0 16v turbo.

And btw, you can get whatever power/torque out of the 8v, it ALL depends on boost. Key is compund turbocharging. It's been done, it's not easy but nothing is easy if you want to push the limits. For example developing custom 16v head or going compund turbocharging.

I've seen a Moskvich (remember Top Gear episode? that particular car was bought from Estonia ) that uses compund turbocharging.
It has two turbochargers mounted at the back (where back seat used to be), modified original engine, 3bar+ boost and around 800hp. On concrete track (old Soviet airfield) it made 9.5s passes @ 240+ kph traps. Car is mostly hand-made, no bling:) Uses Hestec engine management, second hand pistons, rods etc. Gearbox is the most expensive part, it's sequential dog-box of some kind.
It may be hard to believe but he doesn't have to take a wrench in his hand during race weekend, the setup is working flawlessly.











And here a Youtube video of this car: http://www.youtube.com/watch?v=maf7pMc2lAY

My point is, ANYTHING can be made and 931 head flows eccellent compared to Moskvich head
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
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ic932  



Joined: 11 Feb 2005
Posts: 1104
Location: UK

PostPosted: Thu May 14, 2009 7:27 pm    Post subject: Reply with quote

Was'nt compound turbocharging pionneered by the tractor-pulling brigade for its excellent low down torque ability.

I must say, I've never been a fan of drag racing at all, but i like that Moskavich project

Anyway Steve, whats to stop you developing both 931 and M44/? engines. Afterall, same bodyshell/running gear needed. A quick ECU change, engine out, engine in...pure plug-in & play

IMO, the higher usable HP for the lowest amount of boost will always win the day.
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Raceboy  



Joined: 01 Mar 2004
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Location: Estonia, Europe

PostPosted: Fri May 15, 2009 3:22 am    Post subject: Reply with quote

No it's not, it's the durability and power that wins the day (or race). 924 block is MUCH stronger than 944 block will ever be.
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
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Shurick  



Joined: 15 May 2005
Posts: 508
Location: Russia, Moscow.

PostPosted: Fri May 15, 2009 3:53 am    Post subject: Reply with quote

Raceboy the Moskvich head (and the whole engine) isn't as horrible as all other parts of the car. It's a copy of some old BMW engine, AFAIK.=)
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'79 931 -- intercooled K26-3060-6.10 turbo @ 1.2 bar, EFI+EDIS, 951S brakes, stripped interior, 951 look.
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Raceboy  



Joined: 01 Mar 2004
Posts: 2322
Location: Estonia, Europe

PostPosted: Fri May 15, 2009 4:32 am    Post subject: Reply with quote

Ahh, that's a legend only that engine is M10 replica. No parts are interchangeable and Moskvich head flows only a mere 130 cfm in stock form.

I've dealt with these engines since when I was a child (Lada and Moskvich)
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
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ic932  



Joined: 11 Feb 2005
Posts: 1104
Location: UK

PostPosted: Fri May 15, 2009 7:04 am    Post subject: Reply with quote

Raceboy wrote:
No it's not, it's the durability and power that wins the day (or race). 924 block is MUCH stronger than 944 block will ever be.


So what block are you going to use on your 924GTP replica? Will it be making the fully tuned (but unreliable) 600bhp or will the de-tuned 410bhp be enough?

944 blocks are strong enough...thats all that matters.
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Raceboy  



Joined: 01 Mar 2004
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Location: Estonia, Europe

PostPosted: Fri May 15, 2009 7:30 am    Post subject: Reply with quote

Since my 924 GTP is a street-car, it really doesn't matter how much to push it. Street car hardly sees more than few tens of seconds of full boost at a time but most likely I'll settle wiht around 400-450 rwhp.

Quote:
944 blocks are strong enough...thats all that matters.


That's the problem, they aren't! Again, for a street car it's ok and even on those the block starts to fail at around 600 hp. Guess what, even Honda 1.6liter (iron) block withstands 600hp without a hitch as do 924. It's originally designed for diesel, that says it all.

When it comes to race engine that has to last, 924 block is much better choice, hands down. Head is another story but I'd rather have half a bar more boost to compensate less flow than failed engine on race season that already had cost me very big money.

Imagine having 4-6 races on the season and cost per race is around 1000-2000EUR and you have engine failure that's going to cost additionally plus the waste of valuable points, or title.
No go.
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche
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