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rallyboy77 · Alfasud Joined: 08 Apr 2003 Posts: 76 Location: Sydney

Hi Guys,

I'm after some input as to the best (and most efficient) way to build up a motor for my alfasud rally car. I'm not looking for an ultra hot race motor here, just something with a bit more power than stock, and runs reliably.

Now I already have a block bored to 87mm which is decked to around 10.5:1 CR. A lightened and balanced crank (from a 1.5) and lightened and balanced rod's (from a 1.5)... this makes a 1600cc motor (good as > 1600cc puts me in the next class against to 2ltrs).

My idea was to get some cams ground up (not sure of exact specs yet), and replace the tappets with the shimmed tappet buckets type. Valves... from the 1.7, 40mm inlet and 33mm exhaust I think? Stock 87mm pistons fly cut to fit the new cam / valves. Pair of 40mm IDF webers for induction.

I;m not rich as otherwise I'd go for efi, and the forged option... does this sound like a reasonable plan??

thanks guys,

jeremy

Toad · Alfasud Joined: 19 Mar 2003 Posts: 42

http://www.alfaboxertuning.fws1.com/
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Shift for Brains

alexj · Posted: Mon Jul 21, 2003 2:35 pm Post subject:

What sort of heads does it have.... you say "replace the tappets with the shimmed tappet buckets type". So is yours the early alfasud type with allen key adjustment of valve clearance? Can you adapt the head to suit, or is it more simple to fit the later style heads?

How much power were you hoping for and at what revs? At lot of the race guys are using 44mm IDF (or 45 dellorto), but torque is probably more important than top end power for a rally car, so maybe best to stick with 40's.

I guess you've seen the Cars and Car Conversions article on Alfa Boxer tuning?
Regards, Lex

rallyboy77 · Alfasud Joined: 08 Apr 2003 Posts: 76 Location: Sydney

Hey Alex,

I have a set of heads off an 8valve 33, they have 40mm inlet valves. The cams are the twin lobe type... I was told they are more expensive to get reground as they charge for each lobe. But Kent and Piper both charge the same for the twin lobe and the later single lobe cams so I reckon keep the twin lobes (no shim throw?). What do you think?

The 40mm idf's are "cheap" to get from the UK, off an old Alfa 33... that is the main reason I was looking at them.

Power wise, not sure I find it hard to estimate. 130 or so hp would be nice..? is that reasonable? Revving to about 8000...

Yep seen that article,

jez

Mixsynth · Posted: Tue Jul 22, 2003 11:15 am Post subject:

I know you've got a block already... but if you want to go to 130bhp cheaply then it's probably easier to get hold of a 16V and do that up. You then get 137bhp stock to work up from.
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Hugh B
'98 145 QV
'89 33 1.7 16V Veloce SportWagon (in hibernation)
16V conversion pics/videos - now updated with extra pictures and explanations

Dave_NZ · Posted: Tue Jul 22, 2003 12:11 pm Post subject:

i agree with the earlier post that torque is still important, due to the nature of rallying. therefore 16V would not be such a good idea. it is also not as robust as the 8V which is also a must for rallying.

cheers

Dave
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Looking for a type 2 33QV in NL

Jas · Posted: Tue Jul 22, 2003 1:15 pm Post subject: cams & carbs

have to agree with dave on that one. The 8v will be bullet proof compared to the 16 for rally. how tight are the tracks you race on? If they are fairly tight, you may benefit from 36mm carbs and a short duration cam.
36's will pull you out of a hair pin with more control than 40's. I guess it's a trade off....horses for courses. carbs aren't so hard to swap to suit your track and conditions. They have to be ready to marry the cams though.

rallyboy77 · Alfasud Joined: 08 Apr 2003 Posts: 76 Location: Sydney

Hey Guys,

If I could fit a 16V I would do that straight away (no question). But the rules do not allow a change in the number of valves or cams, so it sort of rules that on out Smile

The engine currently has 36mm IDF's and a short duration cam, it's the stock motor, and quite underpowered Smile

Rally terrian varies quite a lot, from very tight to very open.

Jez

lesthegringo · Alfasud Joined: 23 Jul 2003 Posts: 97

I put a 16v with injection in my Sprint (see my site www.alfasprint16v.fws1.com ), and while it was an interesting challenge I have to say that I would not do it again.

The 16v does suffer from a lack of low down torque, so you have to rev the nuts off it to get it down the road quickly. The injection helps, but the problem is that it is a front wheel drive car with suspension designed in 1969...... It really isn't that good at handling the power.

What I have concluded is that a well set up 1.7 8v, with aftermarket injection using 40mm throttle bodies and a slightly wilder set of cams, would be the best compromise. This would give you more mid range torque, without sacrificing any bottom end. The slight lack of power at the top end would, in my opinion, be unnoticeable. What you would get is a more balanced car, that would pull strongly out of slow corners - a must for Rally, and quite frankly the best situation for the road, as it makes for a relaxed rapid car.

If you are not allowed the injection, remember that the cam will almost always lose you bottom end. You will have to be careful with the design of the exhaust manifold (controlled vortex) and inlet valve and port shape in order to ensure that the engine comes up 'on the cam' as soon as possible. 36 carbs will help low down torque, but for a 1.7, the 40's would be better for the mid and high range. The later engines with the larger inlet valve size are the ones to go for. Remember also that longer intake manifolds can help increase torque, so long as they are not too large a diameter, due to pulse tuning effects.

Someone mentioned my boxer tuning site above, that may help you modify some of the parts yourself. Having said that, I would say that properly done, a very torquey 125bhp is attainable.

Good luck

Les

alexj · Posted: Wed Jul 23, 2003 1:59 pm Post subject:

My car is setup for the trofeo class in alfa racing in New Zealand. Most cars in that class are running Weber 36mm IDF carbs (or Dellorto equiv) and are 1490cc 8-valve and either 4->1 or 4->2->1 exhaust. The class rules limit the cams to a maximum of 10.0 mm lift and 292 degrees duration. Can't remember my exact cam profile, but I think it might not be quite to these limits... something less. Unless you are going to real big lift (more than 10mm?) the split lobe cam design should be fine.

The engines in these cars are probably producing about 120-125bhp on race gas, and have reasonable torque (quite road driveable), so 130bhp should be reasonably straighforward with 40mm IDF and 1600cc.

You shouldn't need to rev to 8000rpm either -- not unless you after real big power and are using big carbs and big revs to get it.

It would still pay to upgrade the bottom end to cope with the higher power and revs. e.g. upgrade oil pump, improve oiling of centre main bearing.... but for those details you have to ask a real expert.

Regarding the carbs, you might get by o.k. with 36mm carbs, but there is not harm in going to 40mm carbs. Remember, standard 1490cc sud engine with twin 36mm carbs are using 30mm main venturis and 40mm carbs from 1.7 alfa 33, are using 32mm venturis which is not a big difference. If you get your 40mm carbs off a 1.5 they are actually 30mm venturis like the sud. If you try 32mm venturis and loose too much torque, you can always swap to 30mm venturis - you have a wider range with the 40mm carbs.

B.T.W. if the 40mm carbs come off a 1350 then the main venturis will be 28mm and you might loose top end, compared with the standard carbs on the sud, so make sure of the main venturis!

Regards, Lex

P.S. does this help answer the cam question too?

rallyboy77 · Alfasud Joined: 08 Apr 2003 Posts: 76 Location: Sydney

Hey thanks guys,

Yep those answers do help.

Alex, can I ask where you guys get your cams done?

Who is a real expert? Smile

Jez

alexj · Posted: Sat Aug 02, 2003 9:15 am Post subject:

Eddie W · Posted: Thu Aug 28, 2003 11:26 pm Post subject:

Jeremy.
Interesting project! An oil cooler would be a must ,especially with a sumpguard. My old rally car (1800cc Escort) picked up a lot of tractability when the current owner fitted a big bore "anti reversion" exhaust. With an A6 cam it used come on the gravy stroke at 4000+rpm, with the new exhaust it would pull from 2-2500. It still beats a lot of 4wd cars. Such an exhaust for the Sud would need special care to tuck the pipes up out of the way. Do you still run the inboard brakes? A lot of Fiats had 40mm carbs. I would certainly use them myself in your car. If you`re ever up Auck way with the car let me know at willco7@hotmail.com as I would like to see it . I used to mod rally cars for a living and could show you the most immaculate rallycar build you`ve ever seen. Smile

Regards Eddie

rallyboy77 · Alfasud Joined: 08 Apr 2003 Posts: 76 Location: Sydney

Hey Eddie,
Yes I was in Auckland last year to see rally NZ, was great! So is your rally car more immaculate than the WRC's ? Wink

The anti-reversion exhaust thing sounds like an interesting idea, will have to check it out...

jez

Eddie W · Posted: Fri Aug 29, 2003 10:48 pm Post subject:

Hi Jeremy.
My old rally car was an Escort 1800 pushrod with a chambered xflow head and is still run occasionally. The immaculate build I was talking about is a Datsun 510 with EJ20 motor and is being built by the sons of my best friend. They make most of their own bits including carbon fibre body parts,dry sump and pump,tanks ,cog belt pulleys,steel flywheel,gear ratios ,adjustable suspension, etc,etc,etc. And yes it is all done to a standard that would not disgrace a WRC car. For some stupid reason I got it in my head that you lived in NZ but if you`re ever back in NZ ,contact me and I`ll take you to see it. I`ve never driven a FWD in anger on loose metal and the thought of left foot braking with the Alfa pedal spacing is quite unerving Rolling Eyes

. I`d love to follow the development of your project though so stay in touch. For a big bore anti r exhaust though you may have to use adaptor flanges with the anti r tube welded and bolted to the head with countersunk cap screws.This plate then has tapped holes offset from the original mounts by 45-90 degrees and the big bore sits over the top and bolts to these. I hope you can follow all that.
Regards Eddie