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75evo
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Re: 24v headwork - power gains

Post by 75evo »

Makes the new brera engine look very attractive now, 90mm stroke. But the Direct injection nature makes it a mystery for me.
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Re: 24v headwork - power gains

Post by Duk »

JimGreek wrote:Hold on there!!!! How does aknowledging superior engineering make me ignorant?? :mrgreen: :wall:
Jim K.
JimGreek wrote: I'm referring to the M3 3liter (286hp). As far as ricer power, I can't believe anyone will consider the 3.8 GT-R too shabby, as well as the NA 350Z. Simply better than ours; truth is ours is ~30 years old and that's our only excuse; or is it? Jim K.
You seem to be forgetting some of the great engines that came from Japan.

Honda's C32B engine that powered the NSX.

Toyota's 2JZGTE twin turbo engine, an engine that has proved itself both in terms of pure physical strength and power potential. While its peek power was about the same as the M3's, it was well and truly against the Japanese limit of 280hp, but they made 450Nm of torque at 3600rpm. The M3 engine wouldn't ever produce that at any engine speed.
The legendary 4AGE series of engines.

Nissan RB26DETT engines that powered the R32, R33 and R34 GTR's.
Nissan FJ20 4 cylinder engines that apparently started life as the FJ15 engine during the turbo era of F1.

Mitsubishi's 4G63 engines that have been around for absolute ages powering the Evo series of Lancers amongst other cars.

Yeah, the M3 3liter 286hp was an excellent achievement but BMW weren't the only car manufacturer that could make grunt back in the days of the E36.
And I'd put money on most of the Japanese engines (especially the 2JZGTE) being physically more durable, much better priced to buy and cheaper to rebuild and modify.
Last edited by Duk on Sat Oct 20, 2012 5:15 pm, edited 1 time in total.
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Re: 24v headwork - power gains

Post by Duk »

75evo wrote:Makes the new brera engine look very attractive now, 90mm stroke. But the Direct injection nature makes it a mystery for me.
Yeah, but the Australian Holden Commodore engine on which the Brera engine based (apparent;y the Alfa heads are even built in same factory as the Commodore in Adelaide, South Australia) is much more readily available and starts life as a 3.6 litre engine that powers our fat taxi's. Read: Plenty of low RPM torque, but still go on to produce, depending on what model of the engine, 190Kw.
Most of them used the more realistic to run with a programmable computer, port fuel injection.
Note they these engines also use continuously variable valve timing on all 4 camshafts. There aren't a whole lot of programmable computers that can run that kind of show.
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Re: 24v headwork - power gains

Post by storm_rider_ »

Have to wonder what bell housing pattern the later motor has and at least in holden form they are rear wheel drive and have the manual 6 speed gearboxs fitted from factory and cheap enough that would solve the transaxle problems strength to especially if turboing.

I was talking to a guy i know that races a mazda mx5 turbo around taupo track. He got his arse handed to him by a r33 skyline which wasn't uncommon but thought the noise of the car was all wrong. Latter he caught up with him in the pits and it turned out he had a 4 ltr ba falcon turbo motor producing 750hp in the skyline lol. Now that to me is an awesome motor.
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75evo
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Re: 24v headwork - power gains

Post by 75evo »

I just checked, the NSX has a 78mm stroke, both for the 3.0 and 3.2. So 78mm isn't too bad, but the car must be relatively light and have effective gearing.

Ok for a daily driver, 86mm stroke is good. But in a car like the 75 which is very light by todays standards, the extra stroke doesnt seem to be necessary.
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Re: 24v headwork - power gains

Post by Jim K »

86mm stroke is not necessary but very desirable!
I'm sure there are many good engines out there and the moral (to me) is we have no special reason to be proud of our V6; we just happened to be stuck with it for many different reasons. I cite the BMW, as we see many of those here and very few GT-R's, even fewer SX-300... Now Porsche... a whole bunch of them, in a country leading the world in corruption and tax evasion. But we're digressing...
Anyway, the goal here is to sensibly increase overall 24v performance in spite of the short stroke. I have to ask Greg, how complicated it would be to develop a variant of his 12v kit for the 24v? I mentioned sometime ago, that had I known about his kits, I wouldn't have messed so deep with the V6. Maybe some careful blueprinting, balancing, a good exhaust system and that's it. In financial terms it could be beneficial too, having to offset cost of special rods (~$600), pistons (~$1200), cams (~$500 regrind), valves (~$500) and headwork (~$800), totalling ~$3600!
I personally definitely prefer SC vs turbo for many reasons. Other than this I'm afraid the only recourse is smaller ports but I'l let someone else pave the way here, unless I can find a set of 2.5liter heads for almost nothing (difficult). I'll try finding/borrowing a head and take it to the flowbench first, but I have no timeframe for this.
Probably THE most important aspect is gearing! Doing the math with gta gears, I found its almost identical to having a 75 1.6 box!!!! Case closed!! My low speed complaints arise from the fact I have the 1.8T box (4.56:1 vs 3.91:)1. In a couple of weeks I'll put in the TS box (4.1:1) enhanced with 3rd/4th gears from the Alfetta and THEN I'll report on it. :wink:
Jim K.
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Re: 24v headwork - power gains

Post by kevin »

From my side what I have found incredible about the standard 24v head is that in standard form It suits the 3.7 conversion perfectly . I was the only person here who never modified the ports , or put big valves or even change the throttle body my engine power is not far off :wink: the best engines with itb etc . ( probably the main reason I did not do this is because I would not have known what I was doing any way :D ) but the cams I have which I bought glen wood made huge difference . It was same cam I also used in the 3.0 24v .
Having said that I am 30kw down on the best 3.7 here but I am more than happy with 192 kw on wheels with standard pump fuel .
Last edited by kevin on Sun Oct 21, 2012 4:46 am, edited 1 time in total.
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Re: 24v headwork - power gains

Post by Giuliettaevo2 »

Mats wrote:
The problem isn't the short stroke, it's the short rod... :lol:
But bottoming out due to a longer rod isn't to pleasant... :oops:
Drive it like you stole it...
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Re: 24v headwork - power gains

Post by kevin »

Ha ha , you need harder springs then :D
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Re: 24v headwork - power gains

Post by Mats »

or a new block... 8)

In some cases it can be fixed with a thicker head gasket. :lol:
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Re: 24v headwork - power gains

Post by Giuliettaevo2 »

Some Powerflex bumpstops would work well i guess... :lol:
Image

We'd better get back on topic now.
Drive it like you stole it...
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Re: 24v headwork - power gains

Post by Jim K »

Rats...I can't dig up the 24v 2.5liter valve sizes anywhere! Anyone know what they are??
Kevin, there's huge potential in the 3liter 24v heads. I would say they're capable of more than 160cfm and theoretically, that is good for ~69hp/cylinder, or ...414hp, when coupled with the right cams and exhaust!!But this would occur at ~8800rpm in a 3.7liter engine.... :roll: The 3liter would do the same at ...~10500rpm!! :shock: So, I would say you were right in not porting! The std head has 138cfm and with a light cleanup gets 146cfm, good for up to 365hp at 9k for the 3liter and at 7.6k for the 3.7liter. Too bad there isn't a destroyed head around here. I'd port one cylinder just to verify the numbers.
Jim K.
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Re: 24v headwork - power gains

Post by 75evo »

Evo2

Don't forget good lubrication. Sometimes they like synthetic. But I heard the Greekster specializes in fixing the pump to make sure lube is good at high rpms :lol:
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Re: 24v headwork - power gains

Post by 75evo »

Btw Larry of Alfa Parts Exchange has titanium valve retainers for the 24v to ring down the weight if anyone is interested. He is the guy who did the 24 conversion on his gtv6 back in 2000 and has stainless header for 24v conversions
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Re: 24v headwork - power gains

Post by Jim K »

Good oil(a) + reworked pump(b) + proper clearances(c) = reliability
Unfortunately, most people neglect b and c and then blame whatever mishaps on oil and high revs... :roll:
Properly measured and set 24v std parts are good for more than 7800rpm, so no need for Ti retainers. Spaghetti-type headers though are good, with primaries ~550mm.
Jim K.
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