ALFAGTV6.COM

[Mats]

Maybe they factor in emissions?

But as you say, difficult to say without the curves. Off the seat or 5 thou?

[Tim0172]

Interesting!

Its 5 thou/1.25mm Mats.

I have a set of C&B road medium (9.9 mm intake lift and little more duration at 268 seat to seat) so a little more duration then the road max profile according to C&B.
Wonder how much duration they have at 1.25mm?
One thing thats strange is this;

AR24.SM2 Road medium int 9.9 exh 9.4 int 268° exh 272°

AR24.ST1 Road max int 10.4 exh 9.2 int 260° exh 274°

These are the C&B cam data from there website.
If you see these numbers there is a difference in seat to seat duration between intake and exhaust.
How come if you measure them the intake and exhaust duration numbers are the same?
Surely comparing duration at 1.25mm to seat duration would give less duration but still the difference between int and exh would be still there?

Am I missing something?

[Jim K]

Here is a direct comparison of 4 profiles, from the inside out: std 3liter, gta, 10mm, 10.3mm. The differences are clear -although difficult to see in this print. Idle quality is greatly influenced by overlap area, so adjustments must be made to lobe centers. Sorry about the pic quality, that's how it came out of the pic-post site.
Jim K.

[yetyGTA]

Jim, Alain. May I have a question on bob weights? Together with t a friend here we are planning to build a set for different 24V engines we have. Following Jims book there are few things unclear.

1. do you weight the big end with the bearing?
2. What is the typical big end and small end weight on an OEM 3.2?
3. Is it possible that 3,2 pistons are much lighter than 3,0? I measured 400g piston with rings and 128g the pin+lockrings. It is aproximately 100g less than 3,0 pistons by Jims book.

[75evo]

yety where did you get your piston ring set? I bought mine from Autolusso for USD400! Ouch.... Even the forged rods were only USD450 or so.

[kevin]

I remember the gta pistons having much shorter skirts than the 3.0 pistons . Might explain the 100 g

[yetyGTA]

Hello Evo. The rings are from another 3.2 engine a friend of mine bought just because of the crankshaft. It was cheaper to by the whole engine. He has actually done the measurements. My 3.0 is still not opened.

Thanks Kevin.

[Saabretooth]

Just wanted to update.

I downsized my throttle body to 78mm from 84 mm and went fit the dyno after the car adapted for about 4 to 5 months.


Other than the first run of 275 hp where the carpet was stuck under the pedal. ...

I got 297 hp and 301hp respectively at just under 7000 rpm for the next 2 runs. Both on 98 Ron fuel.

Torque was at 326 and 330 nm.


Spoke to my mech and he asked whether I could get
1.forged and lightened pistons.
2. Piston heads that could increase capacity (at least that's what i think he said)
3. Lightened rods and shafts
4. Stiffer springs for the lifters (or the solid lifters a la jim K. )
And he'll do the job for me.

Lol that will be when my car crosses 100k km. It's at 78 k now. Should be a June 15 job.

[Jim K]

I believe you don't need any forged stuff if you keep under 8krpm. Same goes for valve springs. As they are, my springs/hyd. followers went to 7800, where the dyno operator detected pump-up (noise -monitored with headphones- changes at those rpm and engine doesn't rev higher). That's NOT v/p contact, just lifter pump-up. Then again, why go solid if your cams are best under 7800?
Your piston speed is <4000fpm at ~7700rpm, so you don't have to worry. Std parts are of good quality and my doing >100 hard laps over a track weekend with ~7600rpm shifts proves this. If you're not going to live at the track, I wouldn't go forged, however balancing of the std parts is a must. But if you want to gradually upgrade to the max, you will obviously spend the bucks/rubles/euros/gold/clams for forged parts. And if you like cornering a lot, you must definitely invest in a scraper/baffle set from Ishihara-Johnson.
Jim K.

[Saabretooth]

Thanks Jim, I'm liking you even more now.


Currently I've limited the 3.2 to 7300rpm.

If I were to raise it to 7600, I should not have much else to do other than the balancing,widening the oil supply to the followers and the recommended baffles, as I take the corners aggressively.



It's probably just an itch that I want to scratch in maximizing the engine potential with all the lifters, rods and pistons stuff.

[Jim K]

It all boils down to spare $$$ -as usual!
Jim K.

[Saabretooth]

It all boils down to spare $$$ -as usual!
Jim K.

Haha, my itch doesn't cost that much to scratch .... ..... ..... ... yet.

Lets see if I can raise some extra funds by next year and see where it goes.

Saw that you wanted to do a group buy for some stuff.

If we can can get it going here, let me know how much and I'll see if I can participate. Let see how much I can set aside by then.

For me, its a Road/Track car as opposed to the Track/Road car as you have clearly highlighted.

[Jim K]

I don't think the group buy is going to fly. It concerns the rods. My JK/THS rods have the proper offset, the Chink ones I got for the 3.2 don't. I would like to have the proper ones but I can't. We put Chink rods in another 2liter V6 turbo here and no problems -its been a year now. There is another ebay seller from Oz selling sets with offset (I wrote and asked) but they are a bit expensive at £530 (shpg included). I thought about it -still am- but I've already set my bobweights for the Ching rods and it took me a few days to balance/equalize them. Don't know. I'll wait until I return from vacation and maybe there will be some spare coins jingling in the pocket! So far, this engine has passed the 6500€ mark in parts -all documented. I have never thought of what a similar complete engine should reasonably cost, but that can be a no-end discussion. Then again, labor is my case is zero.
Jim K.

[75evo]

Saber

Might as well go for the super sprint copy headers sold on ebay. That could give you an extra 10-15 bhp.

Forged pistons aren't going to make a huge difference unless the static compression goes to 11.5:1 or something substantially higher. Besides I thought the your cyl were already skimmed?

[Jim K]

Make up your mind what cr you want first, before ordering peestones. CPS at least, ask what cr you want but of course they assume an uncut head. So if you don't mill at all and order 11.5:1, you should be able to measure 11.5:1. I don't remember what cr I ordered mine for but When they go in the block, I will cc with the std heads. CCíng a V6 is a bitch, unless you have the flywheel type engine mount which you can rotate to bring the gasket in a horizontal position. Me...I'll just have to raise one side of the engine stand high enough to do this; hell of a clumsy job!
Jim K.