Ax Gt Conversion To Bike Bodies

[robi1000 0]

Hello!

 

I hope you guys don't mind that I post on this forum, but my little AX has the same engine as 205 Rallye (it's not 1.4 anymore, now it will be 1.3 euro rallye engine with bike bodies - R6).

 

One problem I got now is how to make intake tract long enough. It's supposed to be around 38 cm from the valve in the head. That means about 30cm without the port. Clearance from the head (where intake ports are) to the body is 28 cm. I could solve this problem if I cut some bodywork. Problem is, behind that metal I'd have to cut out is a heater matrix. Can heater matrix be relocated?

 

So I was hoping that some of you guys have some experiance with AX or maybe have a friend that has done something similar...

 

Any help would be appreciated.

 

Robi

[RossD 43]

GMC make a manifold that actually curves over the top of the engine to get the inlet tract right, maybe look into doing something like that? The carbs\bodies then sit almost on top of the rocker cover. As long as the bore of the manifold is wide enough, you shouldn't see any losses from the resulting curvature of the manifold.

[kyepan 291]

on 106's some people cut the scuttle, perhaps pm sandy as he is familiar with the technique.

 

J

[robi1000 0]

My friend will make inlet manifolds (we both have AX GT that are going to be run on bike carbs). He's done one for 106 before.

 

I don't think there's enough space for carbs to sit "on" rocker cover. Maybe if they were moved towards the windscreen. But that would complicate manifold fabrication. About cutting in the scuttle...

 

 

It was done on 106 Rallye, but the problem with AX is that it has a single wiper and the mechanism moving it is just where I'd have to cut in the scuttle. I'll have to think of the way to move that mechanism on the other side.

 

But the easiest way would be to move the heater matrix somewhere else and cut a hole in there.

[Roman 0]

or maibe twist engine 180degre joke... i think you better spent the money on you another project(williams) and put beast on street again...

[robi1000 0]

He he, "beast" is scheduled to be unleashed (mechanically) somewhere in the summer time. I have to sort out the suspension and save for a complete respray. Costs a lot of money compared to this project.

 

You should find me a nice 205 GTI for my next project or you can just sell me yours (ha ha I know you rather shoot yourself in the leg).

[drmo 5]

Who let you show pictures of my engine bay?

 

Sandy says that 35-38cm overall lenght is optimal. I think that 35 is doable in an ax.

Edited March 22, 2009 by drmo

[BackStreetRacecars 3]

sorry if this is a touch off topic.... but has anyone ever thought about the reverse head ideas used on the touring car vauxhalls for the tu engine? Maybe I'm just waffling garbage... but is it worth looking into for neater carb and t/b situations??

[robi1000 0]

...has anyone ever thought about the reverse head ideas used on the touring car vauxhalls for the tu engine? Maybe I'm just waffling garbage... but is it worth looking into for neater carb and t/b situations??

 

As far as I know it's not really feasable because of the channels in the head.

 

@Drmo: Yeah I measured all the lenghts. From the valve guide to the port face is 9.3 cm. SS plate is 0.8cm thick and carbs(including current trumpet lenghts) is 12cm. Available space from the port face to the metal beneath the windshield is 28 cm. I've decided that I'll leave about 2cm between trumpet and the body. So that is 26cm from the head.

Total length is 26 + 9.3 =35.3 with some space left for custom airbox.

 

I'd like to know one thing. Autodata states that head bolts don't need renewing? Aren't you supposed to change them every time?

 

If it's ok to you guys I'd post some pictures in here and ask a question here and there.

 

Maybe I should start with a small introduction...

 

This is me (on the left) and my best friend (Mitch). We both own AX GTs. Both of us are hard core french car fanatics. I also own Clio Williams and my friend has 205 GTI. He also owns several 205 XS'. Our families own only french cars. Mitch's father owns some older citroens and we have peugeot 607 an 206.

 

 

 

My GT (I am the second owner since new):

 

Mitch's GT(this car used to be a race car):

 

 

 

 

Mitch (you don't want to mess with this guy ) next to his GT, notice the AX Sport rims:

 

 

Two GTs blasting down the road:

 

That's it for today. From now on I will only post pictures regarding modifications.

 

Robi

Edited March 22, 2009 by robi1000

[robi1000 0]

Can somebody tell me what is the squish volume of the stock TU24 head? And how big can be the ring gap on TU24 engine.

 

And some pictures of my project:

 

First I stripped the head and did some cleaning

 

 

 

 

Edited March 28, 2009 by robi1000

[RossD 43]

Volume of the chambers on the TU24 (39mm inlet valve) is 32.5cc

[robi1000 0]

Can somebody please explain why listed CR is so much lower than my calculated one (cyl volume+ squish volume)/squish volume. Even if I throw in gasket thickness and bore and piston dome volume I still get a value way higher than 9.6:1.

[drmo 5]

Becose you are forgeting that ax has dished pistons which have cca. 2cc dish (or even more), the piston at TDC is not flat with the liners (arround 1mm). The correct way is:

 

Displacement = (Bore ÷ 2)2 x 3.14 x Stroke

Head Gasket space = (Bore ÷ 2)2 x 3.14 x Gasket thickness

Deck Height space = (Bore ÷ 2)2 x 3.14 x Deck Height

Compressed Volume = Head Gasket space + Deck Height space +

Piston Top volume + Combustion chamber volume

Uncompressed Volume = Compressed Volume + Displacement

Compression Ratio = Uncompressed volume ÷ Compressed volume

 

or use this site to calculate --> http://www.rbracing-rsr.com/compstaticcalc.html

 

I get the same result with this site or by calculating myself. The standard ax CR is 9.3:1 and with 1.6 head it is 8.4-8.5:1.

 

If you are thinking about K4M engine (ax sport) than the comp ratio should be 9.6:1. The correct figures are:

- gasket thickness 1,27mm

- gasket bore 76mm

- piston dome cca. 3-4cc

- pistons are almost flat with the liners

- bore is the same as 1360 so 75mm

- stroke is much shorter 73,2mm (1360 is 77mm).

 

Some figures are estimations or were found on the internet so not 100% sure they are correct. The cr's for the 8v TUs are: 1.3 (9,6), 1.4 (tu3,tu3s,...9,3), 1.4 xsi (9,9) and 1.6 (10.2)

 

Thats roughly it.

Edited March 29, 2009 by drmo

[robi1000 0]

Hey Drmo!

 

I calculated it again using the site you provided. But again CR is too high for stock engine. It should be 9.6:1 and I get 10.45:1. Maybe I don't know how to do it. Numbers I used are:

 

Bore: 2.95 in

Stroke: 2.88 in

Head Gasket thickness: 0.05 in

Deck Height: 0 in

Piston top volume: -4 in (negative for domed pistons)

Combustion Chamber volume: 32.5 cc (stock chamber volume)

 

And the result is 10.45:1 CR.

 

If I use 3cc dome instead of 4cc and say that the deck height is not 0 but the piston is 0.02in (0.05mm) below deck (liner) height, then I get 9.6:1. Is this correction ok?

 

Using corrected calculations my CR is 10.7:1. But it could go up to 11.6 by using a slimmer gasket (say 0.6mm instead 1.27mm).

[drmo 5]

That is what I was talking about. You can't calculate something without proper measurements and what info we have is just an estimation. You have your engine block apart so why don't you measure the dome volume? Combustion chamber volume can also be debated. All in all take away something here and there and the CR is much higher. I had a paper scan of some spec list in french and the CR stated was 9.6:1. It definitelly is not much higher than tu3s, becouse it has shorter stroke and bigger combustion chamber.

[robi1000 0]

My combustion chambers are around 28,5 so a bit smaller then original. I'll try to measure dome volume.

[robi1000 0]

Dome volume on TU24/M4A engines is 2.22 cc's. Dome diameter is 42mm and dome height is 1.6mm.

 

With this info, stock TU24 CR calculated with that site is 9:1 and 9.88:1 for my engine. And again it doesn't fit.

Edited March 29, 2009 by robi1000

[drmo 5]

That site doesn't calculate in that the head gasket diameter is larger than the piston bore Why are you complicating things. Are you sure that the combustion chamber volume is 32,5cc? Are you sure that the pistons are flat tops or aren't? What is the height of your tu5 head?

 

There are some differences in cr becose you (and me) didn't measure all the things. I also calculated the cr of a standard tu5 and come up with around 10.4:1 cr, and I know that the cr is 10.2, but the thing is i didn't measure the dish volume of a piston, and I did't measure the cc of a combustion chamber. I assume from the things I read that the cc is 33cc and the dish volume is 3cc. These things are all estimations if you don't measure all the things yourself.

 

And I still don't know where are you going with all of this...

[robi1000 0]

Well, but I did measure all this. And I know as a fact the volume for every chamber in my head. I've also measured head height and my head is lowered for 0.9mm compared to stock head. I've also measured my dome volume. About where I'm going with all this... Now I have the chance to measure everything I want with great accuracy so there will be no guessing later when the engine will be in the car.

[drmo 5]

Then you should be happy that you have such high CR. But it all deppends what will the specs be, especialy the cam.

[robi1000 0]

Unfortunately I ran out of money so I'll have to stick with my GT cam for a while, so power figures are not going to be really anything special. When I save some money I'll go with Catcams 4901133 or similar.

 

I could also use XSI cam, but it has no lobe for mechanical fuel pump. Could I use a fuel pump from monotronic engines and a blanking plate where my pump used to be?

[drmo 5]

Like I said before the XSi cam is big bearing so you can not put it in a small bearing head, like the TU5JP head. Big bearing heads are on 1.3 Rallye, 1.4 XSi, 1.6 XSi, 1.6 Rallye.

[robi1000 0]

Yeah I knew I couldn't use Rallye cam, but I thought that XSI (being 1.4) had small bearings. Well, that option is out then. I'm stuck with my ***** cam then.

Edited March 31, 2009 by robi1000

[robi1000 0]

Managed to swap my GT cam for AX sport one. Now I have to make myself a nice inlet manifold. I was wondering how did you guys set up your carbs (if anyone else used R6 carbs)? Any tips?

[swordfish210 20]

Isn't that what you've been PM'ing me about lately