3.0 24V - your suggestions

Saabretooth
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Re: 3.0 24V - your suggestions

Post by Saabretooth » Thu Jul 31, 2014 5:17 pm

Hey Jim,

I'm not sure how high a CR I can safely go with the existing parts.
Heads are already skimmed down by 1.3mm although you said I have safety margin for 1.4mm. Not sure how much compression that would make but I think the CR should be 11.1:1

If that's the case, what piston heads are needed to bring up the static compression to 11.5:1?



75evo, I've already got cheap CF2 Manifolds off the 2.5 V6 156 with locally customized equal length front pipes, they help me get my 300hp at the 7000 rpm limit.



As with most things better to ask a dumb question now or suffer in the long term...
Jim, what does CC mean?
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Re: 3.0 24V - your suggestions

Post by Jim K » Thu Jul 31, 2014 7:00 pm

CC = Cubic Centimeters, but in automotive technical dialect means measuring the volume of something, in our case the combustion chamber to calculate CR (compression ratio). When determining how much to mill from heads, don't forget to make sure of valve/piston clearance. A simple test with very soft springs will verify if you have enough clearance at/around TDC for intake/exhaust valves. 1.2-1.5mm should be ok. Test is of course performed with the cams in place and timed properly -don't laugh, some people forget the cams! :roll: Even better, you can assemble the timing belt, heads, cams and slowly perform the rotation test for v/p clearance without head gaskets. If you can manage two complete revolutions without binding, you know you're 100% safe.
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yetyGTA
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Re: 3.0 24V - your suggestions

Post by yetyGTA » Thu Apr 26, 2018 6:16 pm

Been a long time I have started preparing the 3.0 24V for 116 chasis I did not have yet. Although I put it on hold due to workshop construction project. Always thought I will return back to it and I still might.

However things have turned different and I'm finally a proud owner of the GTV6. Will need some body work and maintenance. However as it is already a 3.5l modification of the 2.5 12V. I will not replace it with 24V. After driving it back home 1200km I felt in love with it. It has such a strong character and seems to be built well by SaVaLi. Might check the cams, ports and the ussual recommendations of Jim K. But otherwise it's a sweat one. Recommend as a period upgrade to underpowered 2.5 12V.

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75evo
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Re: 3.0 24V - your suggestions

Post by 75evo » Fri Apr 27, 2018 8:20 am

Looks good. I too would not bother with a 24V if I already had a 3.5 12V. Pretty sure with 11:1 pistons and good street cams I would be making close to 280 bhp. Plenty for a street/track car with great drivability on the street. Best part is, only a 1 hour timing belt job and period correct look in the engine bay.

Alfa SZ 3.5 with ITBs:
https://youtu.be/gxVwe6BEv4o

What I would do first is change the EFI, and look at improving the inlet and modifying the plenum a little. That alone should give you upwards of 10 bhp and improved drivability. All other upgrades can come later. After all it's built by Sam Van Lingen so I would assume all the usual guide/seals issues have been addressed and the ports should be at least smooth if not ported.
May as well concentrate on suspension and brakes.

BTW did you see the guy on AlfaBB who has a mod to improve timing belt wrap on the 12V pulleys? He can sell the kit for $400 I think. A worthy upgrade! Say good bye to skipped timing belts if the engine turns the wrong way.
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yetyGTA
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Re: 3.0 24V - your suggestions

Post by yetyGTA » Sat Apr 28, 2018 1:01 pm

Thanks Verde. Did you mean this one? - http://www.alfabb.com/bb/forums/milano- ... valve.html

Just by watching the video I can say mine sounds very similar. By looking at the bottom. Seems it has the CSC exhaust with all except the rear muffler removed. Yet still not being too loud.

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To be honest I'm not planning to modify the engine too much. Want to keep it more as a period upgrade. Except some "hidden" modifications such as porting, larger valves, changing of the MAF etc. I'm sure I will get another GTV/75 one day to play with it. One burned GTV6 (only visible in the engine bay) got away from me recently. It was without papers. So a great base ofr racing project all in all.

By the way. What do you mean by removing EFI?

Actually will need to start with body and suspension restoration first.

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75evo
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Re: 3.0 24V - your suggestions

Post by 75evo » Sun Apr 29, 2018 9:48 am

That's sort of right, change the MAF, but not just the MAF, change the whole system, EFI = electronic fuel injection

Change it out to something like Megasquirt 3. Problem with the L-Jet is it's old and the parts are expensive. Especially the air flow meter, if someone has messed around with it, hard to get it back to factory settings.
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