Alfa Romeo Forums banner

1 - 16 of 16 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter #1
Hi,
I had an alfa years ago and have begun to look for a new one.
I love the car as it was, but always wanted more HP. (who doesn't)

How much can I get out of a 2.0 4, without hurting reliability or stressing the gear box or rear end?

Any suggestions on mods to get the extra power?

Thanks.
 

·
Premium Member
Joined
·
2,177 Posts
Hi,
I had an alfa years ago and have begun to look for a new one.
I love the car as it was, but always wanted more HP. (who doesn't)

How much can I get out of a 2.0 4, without hurting reliability or stressing the gear box or rear end?

Any suggestions on mods to get the extra power?

Thanks.
Try searching, it's been discussed here many times.

Short answer, most gains can be found in the head, clean up the ports, bigger valves, cames, intake, and exhaust. And don't forget to get rid of the mechanical fan, that's 5 hp right there!

A lot depends on which model year you're talking about - Spica? Bosch? The Bosch cars have ECU restrictions, and any mechanical modifications you might do will be limited by the ECU. You'll need to go aftermarket to get the most out of the system.

bs
 

·
Registered
Joined
·
186 Posts
Just buy Jim Kartalamakis' book "The alfa romeo DOHC high-performance manual" all your answers are in there...

ISBN 13: 978-1-84584-019-8
ISBN 1845840194
don't know why there are two numbers on the back of the book, but you should be able to find it by now...
 

·
Richard Jemison
Joined
·
7,925 Posts
Making power

It is very easy to get the head to breath. Clean up the bowl area, open the ports enough on the intakes, that it is a strait run past the guides to the bowl area. Do not do any cutting on the bottom. Taper cut the seats so that the stock valves seat on the last .050 on the valve (and on the seats, from that point in should be cut away to the bowl edge of the seat. With a standard size valve this method will flow better than a larger valve on the stock seat which is big as can be fitted OD wise, and putting in larger thinner seats is a waste of $ for any but all out race motors.
Large valves are not a great performance inhancer, unless the rest of the intake system is modified. They are just a larger surface for the intake charge to have to flow around.
Cut the exhaust seat similarly and clean up the bowl area. Use at least .060 for seat.

The best modification for the $$ is to cut the head to get compression up. With a 9.0 compression motor .050 off will give 10.5 which is good with pump gas.

On a Motronic 10.0 motor .030 will get you there.

Cams & cam timing can do the rest.

I`ve posted a pic of the valve seats cut as I do them. No 3 angle mess! This is head ready for cutting surface & lapping in valves.
Rj
 

Attachments

·
Registered
Joined
·
1,085 Posts
Good Sugestions RJ.

One thing I read in Jim Ks book when it first came out was the formula on CR increase per amount milled off the head. Subsquent testing on a lot of heads have verified his caculations. My rule of thumb is that on all 4 cylinder engines: milling .020" raises the CR .4 of a ratio, So .050" off raises one point.
 

·
Richard Jemison
Joined
·
7,925 Posts
CR calculations

If removing a fixed amount of material, lets say .020 from the combustion chamber increases a motor as you say, .4 then the next subsequent cut reduces the volumn in the combustion chamber even more as a perctage of total volumn, as it is a shallow bowl shape. That reduction mathmatically when added to the first increases the compression not .4 but depending on volumn of the chamber a significantly higher amount, because of the loss of a far greater total volumn of space for the stroke volumn to be compressed into.
If a reduction of a 60cc combustion chamber by .020 reduces the volumn to 50cc that is that is a 16.6 % reduction in volumn, the next .020 is going to remove a higher percentage of the volumn of a 50cc combustion chamber.
I find Jim`s use of a "constant" in his formula for reducing volumn linerly in a bowl a bit laughable. Kind of like the exhaust valves & ports too large.......
But wht do I know:rolleyes:
 

·
Richard Jemison
Joined
·
7,925 Posts
Wha...???

Try to hard? Or do it correctly?
If we decide to split a bowl of beer that is 10 inches wide and 4 inches deep and the division is in inches of depth. do you want the 1st inch or 3rd inch??
We can give JJ the 4th:p
 

·
Registered
Joined
·
1,085 Posts
RJ: You folks in Pensacola have strange ways to share a beer.

Here in the Great Pacific Notrhwest, our beer comes in individual bottles.

(I prefer red wine, and we do share a bottle, but keep it hidden in the brown paper bag)

Happy Holidays, G
 

·
Richard Jemison
Joined
·
7,925 Posts
Right way, or

(I prefer red wine, and we do share a bottle, but keep it hidden in the brown paper bag)
George:
So do I.

If we decide to split a bowl of Red wine that is 10 inches wide and 4 inches deep and the division is in inches of depth, other than the last 4th, which is JJ`s, which changes volumn more?:D

Play with some of the compression calculators. The "NOT SO FAST" is the most comprehensive, The link below is simple but takes into effect the non-linear change caused by piston dome volumn ( negatice CCs ie -15) on the resulting final static CR ratio.
* * Automotive Programs by Bowling & Grippo * *
 

·
Registered
Joined
·
8 Posts
Discussion Starter #11
gee guys... I just want to make my spyder fast.
and yes...
I do need a cold one.

Can I just slap on a supper charger, get 40 extra horses and call it a day? I was told I don't need to open the engine up or change the ignition. (yes, better pistons and a better ingnition system would give me 50 to 80 horse.. but I just need enough to make it more fun.)
Pump gas and no change to the other systems in the car. Sounds good to me.

What do you say?
PS.
JJ,
a beer that you can slice into cubes... now thats a STOUT beer. (sorry, could not resist the pun.)
 

·
Registered
Joined
·
4,075 Posts
Well, you certainly can't just "slap on a supercharger". That's a little more complex than it sounds. However I would agree that forced induction is the best way to go. I don't like beer.
 

·
Registered
Joined
·
6,087 Posts
Well, you certainly can't just "slap on a supercharger". That's a little more complex than it sounds. However I would agree that forced induction is the best way to go. I don't like beer.
Greg,

Ballpark guesstimate, accepting all disclaimers you want... How many hours of work do you think it would you to deliver a supercharged set-up? This would include all time spent having to figure things out, any and all mods to the drivetrain, etc., etc., but not for anything radical. Just a solid 50+ rear wheels hp gain over stock, on a series 3.

Best regards,
 

·
Registered
Joined
·
6,087 Posts
...i'm not sure i've ever heard of nitrous on an ALFA, and nobody here has mentioned it so far... anyone have thoughts or experience with this?
I don't know about other BB members, but Nitrous set-ups are nothing new on an Alfa Spider. At the 1997 AROC National Convention in Columbus, one of the attending members covered this well, and presented a series 4 Spider with the set-up, and info on the outfit that does this type of work. (They are an Alfa shop.) People who attended were able to see first-hand the installed components, and attend the informal demo of the power. Of course, I am not proposing this as a solution, since going with Nitrous is something that each person should decide for themselves.

.... surely this is something that Kartalamakis covered in his book? i haven't read it, obviously.
Kartalamakis has covered this, since the first edition which was published in 1995. I'm sure the same concepts that apply to the Mini, are also applicable to an Afla, but there is really no need to go "non-Alfa". Perhaps some of this is new to this Board, as many people who specialize in Alfa performance do not post on the BB, but the knowledge and experience exist.

Best regards,
 

·
Registered
Joined
·
4,075 Posts
Nitrous is not too practical for street use due to it's on or off nature and long term expense. That said, it shouldn't be a problem on any Alfa, although I would probably want to go with a dry system and a very good ems system. I don't trust the factory dry flow manifolding enough to use with a wet nitrous system.

Enrique, all usual disclaimers apply here, and probably any unusual disclaimers because I have not produced a running supercharged Spider.

1. Figuring it out. That's pretty much done. My Spider has a supercharger on it with the associated mounts, inlet and discharge ports and the crank pulley. I have not worked out the belt tensioner yet but I don't anticipate any huge issues there. It will probably be a Dayco brand tensioner (because I like them) and a custom alloy pulley. I do have an intercooler that appears to fit, but it's not on the car. I am undecided if I want to make all the kits intercooled or offer that as an option. It's a big problem because the kit has to be made specifically one way or the other, unlike the V6 kit where an intercooler can be added at any time.

2. I don't plan to test the kit with L-Jet so for cars I put together aftermaket engine managment will be required.

3. Actually finishing this prototype and getting it on the road is THE problem. I have two major customer projects in the shop right now and a third on the way. All are V6s and they are taking up my time. BELIEVE me, my wife is pestering me daily to get the "SuperSpider" operational.

4. Cost...A LOT. We are figuring a total engine overhaul with forged pistons, and upgraded clutch, various other engine mods, new engine managment, fuel injectors, supercharger kit, intercooler, water/meth injection installed out the door will be in excess of 12K! Of course it should be 250hp and idle well and get decent fuel economy.

5. Bolting the kit onto a Spider that doesn't need an engine overhaul will not require a lot of labor, probably about 15 hours. The EMS system will require more.
 

·
Registered
Joined
·
6,087 Posts
Thank for the comprehensive answer, Greg! Your description and cost projection is much appreciated. Absolutely forced induction is a much more cost effective way to increase power, as you get a lot more hp for your buck, but I do understand why it is still a serious $$ commitment. I can't wait to for your announcement of the completion of your "SuperSider" project, but certainly understand the priority that you must give to any customer work. I'll keep my fingers crossed in the hope that you will be in a position to unveil it in Chicago.

Best regards,
 
1 - 16 of 16 Posts
Top