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Tuning & Upgrades Discuss performance enhancements for your Alfa Romeo

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(Post Link) post #1 of 16 Old 15-10-15 Thread Starter
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Busso cylinderhead upgrades

What can I do to get more power from my 3.2 V6 Busso? Currently the figure at the flywheel is 194kW after semi-decat, quad exhaust and mapping. What are suggested mods for:

1. Intake gasflowing and porting?
2. Intake valve modifications?
3. Exhaust valve modifications?
4. Exhaust port matching?

While the heads are off I will also be looking for tuned length downpipes and decat headers.

What could expected power output be after all these mods? Any help will be appreciated.
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Possibly totally useless info for you since it's non-Busso, but similar work on the Peugeot 306 2.0 16v engine takes the power up from 130 to 175bhp (official Peugeot figures) for lightened inlet valves, larger exhaust valves, tuned inlet / exhaust manifolds, flat-top pistons (slight compression increase), oil cooler, double-valve springs and remap (it also pushes max rpm up from 6000 to 7500).

Presumably you'll get a similar increase of around 30% over standard, assuming all other things are equal...
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30% is a bit optimistic in this case. In the peugeot engine the rev limit increase and better breathing would allow for more air flowing through the engine per second. In my case my rev limit will remain similar so the gains will be smaller as I am trying to improving breathing efficiency in the same rev range as stock (My rev limit is 7500rpm as apposed to 7000rpm stock).
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Fit 3.8l conversion? (Or is it 3.6l or 3.7l)
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best value for money mods next is cams without a doubt.. biggest gain v outlay..

larger valves are expensive for modest improvements maybe £500.00 for valves springs £300.00 retainers £100.00 new seats £300.00 etc.. so £1200.00 for a maybe 10% gain if you then have seats blended into ports etc..
and not really needed on standard capacity engine..

if fitting higher lift cams and heads need to be removed for grinding to allow cams to turn modest flow bench work and valve seats can show a good gain for a lot less.
Only tuned length headers are the supersprint items also expensive but I think worth the money as they seem to be very well designed but at £2500.00 im having a set made up..

Jim K has a great thread here with loads of useful info but will need to join another forum.. ALFAGTV6.COM ? View topic - Jim K. 3.2 engine hence my up to date info on latest cams and head works from the man that wrote the only busso tuning book so far..
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Thanks for that Maxiboy. I will deffinitely read through that thread tomorrow.

Does anyone have experience in modding the 3.2 engine? What were your outcomes on head modding? What can I expect?

Is 300bhp at 7500rpm too much to expect?

Last edited by Ian Lusso; 30-10-15 at 08:39.
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I think 300bhp is just about obtainable from 3.2 but i wouldnt be worried about peak figures more about how its drives through the gears and the area under the graph..

I would remove heads skim to increase compression add cams ( re-profiled ) and some mild porting work and revised seats for gains at lower lifts.. that with decent headers and exhaust and maybe some slightly revised inlet manifold work and 70mm throttle body and good remap and you should have some decent gains..

thing is 3.2 ports are large valve sizes are good so wont see massive gains unless you hold them open longer...

I think Barry Henning and dawie de villiers are in your part of the world...
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Maxi and I are both building 3.2 24v engines using some parts and advice from Jim K.

Saabretooth got 301 bhp for a daily driven car. If you want something like 350 bhp, then you would need ported heads, big runners, long tube headers, big exhaust like 2.75", at least 11.5:1 compression, and > 10mm cams which would need some head work to clear the cam lobes from the casting.

I think you will be sacrificing drivability a little. If we had VANOS or iVTEC, it could be a daily driver and pass MoT. With our old school engines, cam lobes meant for 7000 rpm are used at 2000 rpm, so there will be some drawback there.

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Quote:
Originally Posted by 75evo View Post
Maxi and I are both building 3.2 24v engines using some parts and advice from Jim K.
I,m after a 3.7 if i can get it sorted correctly .. lol
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I'm at 280 with CF2 manifolds, custom downpipes, upgraded Cat Back, BMC CDA intake and re-map. I wouldn't want anymore power tbh. It's feels right at its limit as it stands. Thought about stripping out the AC parts(as I don't use anyway) and lose a decent amount of front end weight.
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The problem is that if you start messing with cams you will be really ruining the torque curve shape at low speed and could loose some of the tractability of the engine.
If I was in your position I would do a light turbocharging to give me 350-360 ps with a wide torque band.
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Maxi,

Oh ok, good luck mate. Lots of 3.7 seem to suffer from less than good builds. Make sure all your parts, welding and boring work are top notch and not done by some prat. I know AHM built a 3.7 for a customer in Japan and it seems to be doing real well.

GJR68,

The 3.2s are undercammed. You should look into adjustable pulleys and Jim K's clio cams. I think that's probably the max I would go for a road car.
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Yep, ditto on what Maxi and 75evo said.

I've raised my limiter to 7500 rpm, but I'm doing some more reading and testing to see if I could go higher without having the balance the engine and crank.

The cams with the capacity of the engine, even if there is any loss in the low end, I don't feel it.
Did a few track days on really hot days, car runs reliable and fine.
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my 3.0 had around 270bhp after all the work an without mapping. I think 3.2 should get around 300 without a problem with right work done.
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I am toying with idea of cams and mild work on mines when i eventually do headgaskets. My engine is 130k miles and in a few years when i need another cambelt change i want to strip the engine, repalce everything and do some work to lighten and balance.
At which point i would like to trust a good friend of mine to do some head work and revised cams. I just want to make it a little better, not looking for big power figures, just something a bit more.
At a guess that will probably mean 300hp for all those guys out there looking for numbers, but for me it is more about driveability as it will be staying a road car.
I would probably replace CF2's at same point and fit a set of Wizard manifolds. But i don't expect that will do all too much to anything.
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AHM can regrind your stock cams (mine are regrinded)
head has big enough ports so doesnt need much work, maybe some polishing of exhaust ports and good port matching on the flanges.
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