Finding More Torque/power - 1.6 8v Gravel Spec

[thomasrally 3]

First of all hello to everyone, I've been regulary searching these forums for months before suddenly late last night I received an email saying the memberships were back open, great it was like winning the lottery, ok well almost!

 

I'm running a gravel spec 205gti rally car which has 135bhp@flywheel which isn't useless but not great either so just looking at general ideas or suggestions on where to find more torque/power. For the spec of the engine the power is probably quite good so just looking at which direction I should possibly be looking at to find the most gains from - I'm thinking the head?

 

Okay current engine spec is:

 

Totally standard bottom end

Standard 1.9 head, 3 angle seats, 10.5:1 compression, Kent PT22 camshaft, relapped valves

Group N head gasket

Twin 40 weber with K&N filters

Vernier pulley

Standard manifold with 2 1/4 single box competition exhaust system

Standard dizzy

 

Like I said for the spec the power isn't too bad I don't think, realistically I'm only looking to acheive somewhere around the 145-150bhp figure which hopefully shouldn't be too costly to acheive!

 

Thanks for reading

[bales 1]

I guess you didn't read the bit in the rules in your first post where it says for any technical enquirys search first...

 

There are probably enough threads on here on that subject for you to spend months reading all of them...

 

My useful contribution will be to suggest politely to read around the topics first and them come back with a more specific question.

[DamirGTI 342]

Little bit of head work and raising the CR up to the 11 mark will certainly do the trick regarding torque .. and a little bit more power (depends on head preparation and fueling/ignition adjustments afterwards..)

 

And id sort out that std. spec dizzy asap , in fact , try first just with recurved dizzy and see how it goes then as chaces are that right now the engine runs at the half possible power output because of the wrong dizzy advance spec ...

I've had this issue after the engine mods where done , been using std. spec dizzy for a few months and the engine did go well , better than when it was std. , but then when i fitted proper recurved dizzy -> wooohooo !!!

 

Damir

[Batfink 201]

Read this thread as it includes some good pointers on where to head for some extra power. Mappable ignition for one.

http://forum.205gtidrivers.com/index.php?showtopic=110253

[DrSarty 90 1 Cars]

I think Bales is having a bad day; although he is right.

 

To up the CR you can remove material from the block and liners (decking them), but make sure it's done evenly and when the liners are reseated they are square with the block face, still leaving 0.003" protrusion to bite into the gasket.

 

As Damir said without changing much and spending heaps it's down to management and getting the best of what you have. (The dizzy advance system is mechanical 'management' IMO).

 

Perhaps a 4-2-1 manifold will bring an improvement; they usually do on these engines.

 

Other than that what about looking at other things like a lightened flywheel and alternator pulley. Has your rad been lowered? If not, drop it down and get as much cool air into the carbs as possible.

[thomasrally 3]

Cheers for all the replies so far, I've been through these forums for hours but wanted answers and ideas more specific to my engine spec

[Mark205T45 0]

Im aiming for around 160bhp with my new engine...

 

I think you need a better cam....and get some 45's you will see 150ish bhp then

[omega 82]

Im aiming for around 160bhp with my new engine...

 

I think you need a better cam....and get some 45's you will see 150ish bhp then

 

i think 40s are fine for this amount of power but changing the choke sizes can make a big diffrence

[Mark205T45 0]

i think 40s are fine for this amount of power but changing the choke sizes can make a big diffrence

 

Still think 45's are better for 160bhp, all the rally boys i know with similar power all use 45's

[omega 82]

Still think 45's are better for 160bhp, all the rally boys i know with similar power all use 45's

 

 

ok but a set of 45s are not cheap and hes on a budget

people think that 45s are the ones to have but im sure a WELL set up pair of 40s are plenty for 180 bhp

we need a weber expert then to settle this

[Tom Fenton 1,542]

I'd imagine that for a gravel car it is spread of torque that is more important than outright power. I wouldn't have thought 40's will hurt power and they may well help with torque.

[Rippthrough 98]

Depends what size chokes you're running, but we use to run a pair of downdraft 40's, with 34mm chokes, on a 190bhp autograsser, going to 45's on 38mm chokes didn't make any difference to the power, just made the fuelling messy low down.

[omega 82]

thanks tom and rippthrough

 

this was the point i was trying to make,it all depends on the skill of the man setting the car up

[bales 1]

I think Bales is having a bad day; although he is right.

 

Ha ha I was grumpy as it actually hit me for the first time that I dont have a 205 anymore!

 

That and the lack of respect for my huge engineering ego...

 

My sensible contribution is that I would agree with Tom in that I would imagine on 40's you would potentially have a wider spread of power/torque which I would assume is of more use in rallying than a slight top end benefit by using 45's.