Expert answers on Modding a HGT(Mk1,147Bhp)

Boorock · Oct 30, 2004

Guys,

Here'r some atmospheric engine mods that I've been advised to be done by my mechanic.

- Port Polish
(Better Air flow)

- Port Enlargement
(Bigger Ports: 28 to 32 means more air/fuel mix in the combustion chamber & easy flow-out)

- An operation on the cylinder heads > Don't remember the technical term

(Increases the 10:1 compression value to 11:1 or 11.5:1)

- Cat replacement by a half open pipe
(Don't know the correct term)

- Chip Tuning
(By standart superchip programme for HGT or a custom programme build specially for the New HGT's specs.)

- Replacing the FD of the HGT with an Alfa Romeo 2.0 156
( FD values: 3.562 > 16/57(HGT) to 3.867 > 15/58(Alfa 156 or Bravo 1.4) He claims that the car "won't" lose some max.speed but the acceleration will be faster)

- Short-Shifter
(Adopted & tuned from a Tipo. I've tried a short-shifted HGT & the lever moves in a 2cm. distance

U just lose 500-700rpm max !

- Shortened Gear Lever
(As written in the Bravo guide, it will even make the lever stand still)

- No cam replacement (?)

Now.. I need really helpfull step by step comments on those listed mods.

He has done 5 HGTs & they'r running like Beasts...
My HGT is a 98'Mk1 with 52.500Km. on the clock.
Are those mods really worth it ?

What's your opinion ?

What can be the side effects ?

All answers are welcomed

PS: All modding will be done in Ankara/Turkey by a nation-famous mechanic on HGTs & Alfas

Tom · Oct 31, 2004

1) port polishing is a pretty pointless thing, its been shown that polished ports can be worse than unpolished ones. Its done by some tuners to excite the customers.

2) larger ports will slow the airflow, slower airflow will result in worse mixing of the fuel and air at lower revs resulting in worse performance.

3) raising the compression ratio limits your fuel choice but does give good power gains.

5) chip tuning on a modified engine is pointless, the chips are designed for virtually stock engines. Your best bet is a piggyback ECU.

6) Yup, a shorter FD will give better acceleration.

7) why do you loose 500-700RPM with a short shifter? The revs have to drop anyway as you've changed to a different gear ratio

I'd go for cams and a piggyback ECU, leave the ports well alone or just give them a quick cleanup and match them to the manifold correctly.

Anonymous · Oct 31, 2004

sorry, but whats a FD?

Tom · Oct 31, 2004

Final Drive.

Anonymous · Oct 31, 2004

tom, he says...

"- Shortened Gear Lever
(As written in the Bravo guide, it will even make the lever stand still)"

what does that do? and how do you do it?

is it just for comfort or what? sorry to bother you if it sounds dumb. haha.

cheerz

Boorock · Oct 31, 2004

Thanx Tom

Thanx for the immediate reply Tom

Finally we can summarise that;

DO's

FD Replacement
Cat Replacement
Cam Replacement
Raising Comp.Ratio
PiggyBack ECU
Short-Shifter
Shortened Gear Lever

DON'Ts

Port Enlargement
Port Polish
Chip Tuning

Ok. I'll definitely listen your advice but here are some additional questions.

- You haven't mentioned any thing on Cat replacement with a half open-pipe

- As my mechanic says: The ECU has to be re-programmed because of the back pressure loss on the exhaust system. The lower revs will be terrible because of torque loss (If we decide to replace the Cat with the Half open-pipe)
As I can understand the piggyback will do this perfectly for me,Am I right ??

- Short-Shifter: Normally on a standart HGT when u decide to change the gear 2. up to the 3.rd at 6.500rpm; you'll lose 1400-1700rpm.(If you'r lucky & fast enough) Soo..the revs will be at 4.800-5.100rpm. at the 3rd gear & unfortunately it doesn't matter how fast you can change !
The short-shifter will save 800-1.000rpm. minimum & you may catch 5.500-5.700rpm

- Doesn't understand how the larger ports slow the air flow ?

I know I'm asking too much but, you're the only one that I can trust

Cheers..

Tom · Oct 31, 2004

Re: Thanx Tom

If you are going to replace the cat get a custom pipe made, the ones you can buy are a ripoff. I'm not convinced of the benefits of them though.

He is correct that the change in backpressure will loose you torque and a piggyback will be able to compensate.

I still don't get what you mean by the revs. If i change from 2nd to 3rd at 6k in my 1.6 it drops to about 4.4k. Thats purely due to the fact that the speed I'm doing corresponds to 6k in 2nd and 4.4k in 3rd. Having a shorter gear stick won't help

Engine revs = gear ratio x car speed.

Its a fixed ratio.

The car stops accelerating when you change gear as there is no force being applied by the engine so you can safely assume the speed at the start of the gear change is going to be pretty much equal to the speed at the end of the gearchange.

In order for the revs to change from 6k to 5k rather than 4.4k when going from 2nd to 3rd, the car would have to magically accelerate by something like 10MPH while I was changing gear. Now that doesn't happen

Your car should be geared such that if you change gear at peak power (about 6k) the revs should drop to peak torque (about 4k).

David T · Oct 31, 2004

Re: Short-Shifter & others..

"The short-shifter will help you to change the gears up/down (especially up) faster than the standart one"

And ruin your synchromesh is the process.

Boorock · Oct 31, 2004

Short-Shifter & others..

Dear Tom (The Mentor),

U'r definitely right & scientific on the gear ratio/speed & revs calc. but I'll try to explain the point of short-shifter savings as I tired one.

The short-shifter will help you to change the gears up/down (especially up) faster than the standart one. Soo what happens if u can catch a higher rev while changing 2.nd up to 3.rd gear ? (Just for 1 second or less, before the rev is reduced to the calculated value)

The car will attack forward "instantly", just before the revs low down to the fixed ratio & began to raise again (depending on the engine power) as you kicked down the accelerator

This forward moving sometimes cause the famous "torque steer" as we can all experience on changing the gear 1.st up to 2.nd at high revs & when u succeed to shift faster, U can feel the torque steer more. Am I right ?

Ofcourse you can not experience the torque steer on higher gears like the 3.rd,4.th & 5.th !

Soo... By this "torque steer" like forward moving you will have a higher momentum and your engine will rev more quickly, engine will be more responsive than the standart shifted car ?

Finally is there a replacement cam that u can advice for the Mk1 HGT for street use ? I've seen Barianni & Colombo cams on the net but could not succeed to reach their site ? Any ideas about the cam companies ?

Thanx for your time & interest again

Tom · Oct 31, 2004

Re: Short-Shifter & others..

I will tell you now that:

a) you can do that without a shortshifter
b) doing that will destroy your gearbox and clutch
c) it WON'T make you go any quicker

What you fail to understand is the gearbox simply WON'T MESH until the engine revs have dropped. You CANNOT get it into gear while the revs are too high.

The MOMENT you press the clutch the gearbox input shaft speed will drop. You can keep the engine at 6000RPM if you want but this is not the gearbox speed. Once you engage the gear the gearbox input shaft will be spinning at the new speed and when you release the clutch the engine is FORCED to slow down.

From what you describe it sounds like the clutch is slipping for the first second as its simply NOT PHYSICALLY POSSIBLE to do that with the clutch fully engaged.

B&C are about the only company to make cams for Fiats. Apparently they are very good. Alfanige has more details on them.

Craig · Oct 31, 2004

Re: Short-Shifter & others..

B&C ?

Tom · Oct 31, 2004

Re: Short-Shifter & others..

Barianni & Colombo

Anonymous · Oct 31, 2004

Re: Short-Shifter & others..

Tom - to appear on mastermind.
Specialist subject - "more power, more power aargh aargh"

Tom · Oct 31, 2004

Re: Short-Shifter & others..

LOL!

One day I must tune my Bravo

It looks like the piggyback ECU I wanted is not available over here any more

Craig · Oct 31, 2004

Re: Short-Shifter & others..

i'd prefer to use C&B or Colombo & Bariani meself

Tom · Oct 31, 2004

Re: Short-Shifter & others..

Picky picky

Bloody punto drivers

Craig · Oct 31, 2004

Re: Short-Shifter & others..

LOL

have you looked at the smt piggy back ecu?
http://www.perfectpower.com/

Tom · Oct 31, 2004

Re: Short-Shifter & others..

No-one sells it in the UK.

Craig · Oct 31, 2004

Re: Short-Shifter & others..

www.greydevilindustries.com
http://www.ahmotorsports.co.uk

Tegryn Race Engines
Huw scourfield
01239 698393
[email protected]

i got these details from the dealer locator, how up to date they are, i don't know...

i've downloaded the wiring diagrams (12mb!!) and found both our cars, umm...

thomas · Oct 31, 2004

Re: Short-Shifter & others..

Nice site!!

along with Autodelta i have another reason to go for an Alfa V6!

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