Which Bottom End?

[bren_1.3 1]

ok so i have a 1300 euro rallye engine in bits across my worktop,

and as theres no substitute for capacity, is it possible to fit a 1400 xs bottom end to a 1300 cylinder head????

 

i cant see oil ways being different, i can only envisage cylinder bore being different?

 

the engine is for a stage rally car in the 1400 class btw.

 

any ideas? anyone thought about this sort of hybrid monster before?

[cybernck 402 1 Cars]

afaik, you'll end up with compression ratio problems and it won't be a monster.

 

but since the 1.3 engine is in bits anyway, it may be worth trying.

 

hopefully trogboy will see this thread and reply.

[christopher 5 1 Cars]

A TU24 head will fit fine on a TU3 block (or a TU5 for that matter). The TU3 just does not have domed pistons and a longer stoke. So in theory the higher compression volume should make up a bit for the increase in the volume of the combustion chamber (due to no domes). But you have to calculate the exact figures yourself. Standard CR for a TU24 is 9:6

 

I think you can modify the 1360 block also to be very close to 1400cc's I have the article at home in retrocars

 

But I love the shorter stroke. Mine is constantly between 3500 rpm & 7000 rpm

 

As a winter project I am tuning a TU24 engine with a TU5J4 block.

Edited January 18, 2006 by christopher

[boombang 2]

This has been done by a guy on the 106 rallye register.

 

Results weren't too bad, but as said you've got to be careful with piston selection and compression ratio.

 

No idea on effect on volumetric efficiency when running a rallye head on the larger capacity bottom end?

[trogboy 17]

The combustion chamber in the TU24 head is much larger than that in a TU3 head so if you fit it it standard to the TU3 bottom end with the slightly dished pistons you get an uber low compression ratio.

 

I got round this by skimming a fair bit off the head which is why I needed your vernier pully as it threw the cam timing out slightly.

 

I spent an afternoon with a sheet of perspex, a tin of grease, a burette and a litre of parafin to measure the volumes of the combustion chambers in the heads and in the top of the TU3 block directly and used the info to calculate how much I needed to skim to reach my desired compression ratio.

 

If you are interested I still have the spread sheet with the figures in at home.

[Hilgie 16 2 Cars]

A guy overhere runs a 1.3 rallye head on top of a 1.6 block. And it's damn quick!!!

[bren_1.3 1]

trogboy that would be great if you could send me the spreadsheet please!

 

christopher would it be possible for you to sent me the article from retrocars?

 

is it possible to use the 1.3 flat top pistons?

 

and would it be possible to skim the block itself rather than the head?

 

i am genuinely quite excited at the prospect of building this engine so any more hints and tips would be great! cheers people!

[christopher 5 1 Cars]

trogboy that would be great if you could send me the spreadsheet please!

 

christopher would it be possible for you to sent me the article from retrocars?

 

is it possible to use the 1.3 flat top pistons?

 

and would it be possible to skim the block itself rather than the head?

 

i am genuinely quite excited at the prospect of building this engine so any more hints and tips would be great! cheers people!

 

 

All the article says is that 76mm JEP pistons can be fited to the bored liners to give 1397cc. That is what I was getting at. I don't have a scanner sorry:-(

 

is it possible to use the 1.3 flat top pistons?

 

If you mean can you use the 1.3 pistons in the 1.4...Maybe not sure. They are in fact 75mm's same as the 1.4. Whether they fit on the conrods I don't know. But its worth a look i reckon.

 

 

 

If you are interested I still have the spread sheet with the figures in at home.

 

I would be very interested in the TU24 combustion Volume trogboy. Sounds like you did it the right way. I need to calculate the CR and would save me a lot of hassle..

 

 

I just picked up my other engine at the weekend:-)

 

Edited January 18, 2006 by christopher

[bren_1.3 1]

chris just how common are those engines over in europe? can i ask how much you paid for it? or am i being cheeky?

 

id love another TU24 engine!

[christopher 5 1 Cars]

chris just how common are those engines over in europe? can i ask how much you paid for it? or am i being cheeky?

 

id love another TU24 engine!

 

Bren, 1,3 Rallyes are becoming increasingly rare. I seem to find more bent ones then running ones these days. But I looked at a couple of bent ones a few montsh ago, but decided that I don't have enough room.

 

This engine came out of rallye that was bent round a lampost that I bought last year for not a lot and had it stored.

 

Just in parts, i.e the head, inlet, carbs, engine and block and strengthened Diff in the box it's worth at least 4000 Danish Kroner so £400ish

[Guest Eric_205Rallye]

I'm the other guy Hilgert refers to...

 

 

I had an original engine the 1.3 Tu24, only while shifting gear (back instead of up) I blew up the engine

 

So in my search of an new engine I came on the idea to create my own motor. Since it was an TU engine I looked for the biigest TU engine and that was the 1.6.....

 

Since, I'm not an mechanic, it had to be simple, so I chose for the TU5JP engine and had to mount the head of the TU24 engine on it........

 

For some more pleasure I fitted a 284 degrees kent cam on it. You have to use the headgasket from a 306 1.6, and a 205 MA gearbox.

 

So I thought it all out and want to buy the parts, untill someone offers me his engine witch has only driven 2.000 KM, after building itup so I was very lucky and pleased, I bought the complete engine for 700 Euro

 

What do you get when you're ready:

 

Well we had a sprint at the traffic lights with another 205, only he had fitted a MI16 in his GTI, the results were pretty funny I was as fast as he was, we gonna do it again this year only a 2.0 Turbo joins us running on 0,8 boost........

 

So i say goodbye 1.4 hello 1.6

 

Ow

 

The TU24 engine is overhere in Holland sometimes only 200 euro, but you have to fix the engine then (headgasket), the engines are becomming very rare overhere in Holland, as rare as the cars....

 

greetings,

Eric

[bren_1.3 1]

so by all accounts, whatever the TU24 head goes on it becomes a monster!

 

i think its time to get cracking on this....

 

Well we had a sprint at the traffic lights with another 205, only he had fitted a MI16 in his GTI, the results were pretty funny I was as fast as he was, we gonna do it again this year only a 2.0 Turbo joins us running on 0,8 boost........

 

eric are you saying you have around 160bhp from this engine? or are there other factors involved?

 

All the article says is that 76mm JEP pistons can be fited to the bored liners to give 1397cc. That is what I was getting at. I don't have a scanner sorry:-(

 

chris did the article mention where the 76mm JEP pistons could be found?

 

Bren, 1,3 Rallyes are becoming increasingly rare. I seem to find more bent ones then running ones these days. But I looked at a couple of bent ones a few montsh ago, but decided that I don't have enough room

 

i admit i am surprised at their increasing rarity in europe, am i right in thinking the rallye was available in ALL european countries? as im sure you know they were never available in the UK from dealerships.

[Hilgie 16 2 Cars]

I think Erics engine has somewhere near 140bhp. Remember the Rallye is very light, so it might trash a Mi16 GTi anyway.

 

Afaik the 1.3 Rallye was available all over Europe except the UK. I *think* that was because they didn't get the carbs + airbox + brakeservo to fit in the same small space. That's why the UK got the 1.4 Rallye on one twin carb.

[christopher 5 1 Cars]

chris did the article mention where the 76mm JEP pistons could be found?

 

Dunno mate the article was by shenpar www.shenpar.com I bet they know or can get them for you.

 

As far as beating a Mi16 205 well well I don't know. You have to remember that a Rallye has a wet weight of 790kgs and the gearbox ratios are quite short. Mine is mildly tuned (I reckon about 115/20 bhp) and I measured it on a Gtech at 7.8 seconds to 60 (arguable of course) Thats basically the same as a 1.9 Gti.

[Guest Eric_205Rallye]

Brent,

 

I have around 140bhp, and I think my calculation is very close, cause I know for sure that i have 125bhp at the wheels and not at the flywheel......

 

If we take a 205 MI16, what will weight around 900 or more kilo, you get a little hint if I told you that My car weights 794 kilo.....

 

Then we go tot the gearbox, the european version has a sport gearbox witch is close ratio.......

 

Then the carbs the respons on the throttle pedal is just amzingly fast, I had a tuned 205 MI16, but the rallye is insane

 

Then shifting point a 205 MI16 witch has fitted a 309GTI16 gearbox has to sshift gear by 7250 revs, i cab go untill 8000 and win a little space........

 

So that's why the rallye is as fast as a 205MI16, I find it very nice for an 1.6 8v

 

Greetings,

Eric

[trogboy 17]

Right I said I'd dig out the figures and this is what I have come up with.

 

Having looked back at the measurements I took and the calculations I made I can only see the combustion chamber volumes for the TU3 head and the TU24 head. As mentioned previously these were measured directly and are as follows TU3 - 28600, TU24 - 32400. All the volumes are in millimeters cubed as I just found this easiest as the bore and stroke etc are all specified in mm. I would have measured the volume of a used head gasket but I'd already thrown it away so I had to make a couple of assumptions to complete the rest of the calcs. I think they were reasonable though.

 

I calculated the total squish volume per cylinder using the displacement of the cylinder and the standard compression ratio figures. The difference between the two is then the total volume of the compressed head gasket and the volume of the space between the piston crown and the top of the block at TDC. How true this is I don't know as I don't know the accuracy of the compression ratio figures for each engine.

 

Anyhow these are the results -

 

Engine TU3 TU24

Bore 77 77

Stroke 75 73.2

CR 9.3:1 9.6:1

Volume of piston bore 340176 323388

Total Squish volume 40985 37603

Volume of combustion chamber (head) 28600 32400

Volume of head gasket and piston crown 12385 5203

 

(hmm.. the figures and tablesque bit were spaced better than that when I wrote it)

 

Using this data you can see that if you were to fit the TU24 head directly to the TU3 bottom end you would end up with a total squish vloume of 44785mm3 and with the volume of the piston bore being unchanged you'll get a CR in the region of 8.6:1. Not really conducive to big power on my carbed n/a engine but maybe for a turbo?.

 

I then made the (slightly crap) assumption that for the first couple of mm the shape of the combustion chamber in the TU24 head approximates to a cylinder, which is almost does, and hence I could calculate how much i needed to skim off to give me my desired CR.

 

I hope you find this useful but as this is just a hobby for me, someone who does a lot of this kind of thing may be able to spot a mistake (or several) in my workings.

 

I can email out the original excel sheet if anyone want it - just drop me a PM

Edited January 19, 2006 by trogboy

[christopher 5 1 Cars]

Ok I think I got it now this is what I calculate

 

Taking the volume of the combustion chamber for a Tu24, I calculate 32.64 (pretty close to the 32.4 that trogboy measured)

 

 

 

I calculate the CR of a TU24 head on a TU3 block to be 7.98...Not great!!!

 

 

Then I can see what a TU24 is like on a TU5 block its only about 9???

 

 

 

TROGBOY How much did you skim off the TU24 head? Did you manage to do this without damaging the squish shape of the chamber?

 

Eric_205Rallye

 

It looks like I need to skin 1 to 2 mm off the head to bring the CR to 10.1 to 11. How much did you skim off?

I need to up at least in the 10's

[Rippthrough 98]

It looks like I need to skin 1 to 2 mm off the head to bring the CR to 10.1 to 11. How much did you skim off?

I need to up at least in the 10's

 

 

Now that you mention it, how high are people going CR-wise with the TU's?

[christopher 5 1 Cars]

Now that you mention it, how high are people going CR-wise with the TU's?

 

 

A standard 106 Rallye has 10.2 and a cam with a lot of overlap (like mine) needs compression to draw the gasses out and prevent back flow at low revs. I don't have enough right now I think .... I'm not sure how high I will go...maybe in teh 11's somewhere

Edited January 21, 2006 by christopher

[stu_woac 1]

As far as beating a Mi16 205 well well I don't know.

 

when its tune the rally stays with a standard mi'd 205 easy my xs does quite easy and at the moment its on a diet so should be even more fun

Edited January 21, 2006 by stu_woac

[trogboy 17]

I took off 1.19mm to raise the compression to the region of 9.6:1.

 

It's not made much of a difference to the shape of the chambers as the bottom ~1mm of the TU24 chambers are pretty vertical and as my TU3 pistons are dished and stop a preverbial country mile from the top of the bores I can't see that it has caused much of a problem with the squish shape overall.

 

I'd rather have changed the pistons and skimmed material off the top of the block/liners but it was a matter of budget i'm afraid. £40 for the head skim or hundreds for the pistons and the skim.

[bren_1.3 1]

I'd rather have changed the pistons

 

did you consider changing the pistons at all? where you in possesion of a complete TU24 engine or just a cylinder head?

 

as my TU3 pistons are dished and stop a preverbial country mile from the top of the bores I can't see that it has caused much of a problem with the squish shape overall.

 

would you say that it would be possible to take off 1.19mm off the block face rather than the cylinder head? or if given another chance you would have split the 1.19mm between head and block? (budget non-existant)

 

would you be willing to give the specification of your engine (and expected / actual BHP) as perhaps a bench-mark to me/others in building a similar engine?

[trogboy 17]

When I first started this it was supposed to be a cheap and cheerful project so I didn't really condsidered changing the pistons as I was trying to limit what parts I had to buy in. I sourced the head from france specifically to go with a TU3 bottom end so I never had the oppertunity to use the TU24 pistons instead.

 

You could probably take the 1.19mm from the block but you'd also have to have some of the ridge from around the edge of the piston removed to prevent them rising proud of the liners and contacting the head at the top of the stroke.

 

I have taken the engine to pieces again at the moment as I am going to replace the bottom end as it is a bit tired and one of the piston rings is shot. The bottom end is an ally one from a TU3S engine given to me by a friend and I wasn't sure of it's condition appart from it seemed ok in the car it came from. I also think that some of the valve guides are worn on the inlet valves on my TU24 head so this is going off to be measured up and given a once over before I put it all back together and back in the car. It's annoying but I guess I am paying the price of trying to skimp on the first build.

 

I only ran the car for about 6 weeks before I took it off the road because of the appauling amount of blue smoke that was always being churned out. I think what really buggered the bottom end was the silly amount of bore wash that I got trying to set up the carbs myself - again paying the price for being a tight wad. Still, should be good once I am allowed the time off from decorating to do something with it again.

 

Power wise I don't know quite what to expect. The compression ratio is that of a TU24, the head, carbs and hence inlet tract are all standard TU24 and the exhaust (manifold, downpipe etc) is bogo too. The only real difference is the induction which is a pipercross P600 filter and the displacement of the engine which is ~5% greater than that of the TU24 so maybe somewhere in the region of 110BHP. Maybe a bit less as I will be drawing hot air from the engine bay but that is something to consider once it is back together. To be honest I don't really mind the actual power figure as it has to be better than the 75BHP I had before and it has given me something to do.

[christopher 5 1 Cars]

What is really surprising me is that from my calculations the volume of the combustion chanber in a TU24 seems to bigger then a TU5 (and of course a TU3)

[trogboy 17]

I've never seen a TU5 head but aren't the valves slightly bigger than a TU24 head?

 

What about the style of the top of the TU5 pistons? Any chance of some pic Christopher?