Tu 1360 Iron-block Question

[sorrentoaddict 1]

As in title - can anyone confirm what is the max. safe bore dia.

that the XSI 1,360 TU engine (iron block) can be bored to ?

 

Cheers

 

AG

[PumaRacing 2]

Surely it would depend on the loadings you want to put through the block. I've not looked at a TU specifically but for normally aspirated use I've never seen a cast iron block of any type that wouldn't bore by 1.5mm to 2mm although some won't take a lot more. For turbo use you're usually better leaving it stock or at most 1mm. Bore flex will lose you more power than the extra capacity gains you.

 

Wall thickness on modern blocks tends to be thinner and more carefully calculated than on old engines. You could bore old MGBs by 4mm without any problem. More modern Pintos and CVHs take about 2mm, maybe 3mm. A friend tried a CVH at +4mm many years ago and ended up with a pinhole into the water jacket after a year's running.

[Sandy 191]

79.5 is the furthest I've had one bored so far. It's not built up yet, but the feedback from the chap that bores for me is that it was still very stable on the final cut.

 

I previously had a TU5 block bored to 82mm for sleeving, it didn't break through, but the sleeve seemed a bit unstable after about 20k on the road, which might be down to the block cracking around it.

[PumaRacing 2]

79.5 is the furthest I've had one bored so far. It's not built up yet, but the feedback from the chap that bores for me is that it was still very stable on the final cut.

 

You've bored a TU3 out by 4.5mm ????

 

I'll be amazed if that works for long.

[Sandy 191]

No need to be amazed I don't think. It's the same internally as the Diesel (77mm) and TU5 (78.5mm) blocks. The guy that bored this one has a competition engine history that most engine builders might aspire to, including some very famous drivers at the peak of their careers. If he's happy, i'm happy.

 

TB 205GTi has run a TU5 block with 81mm (16v) http://forum.205gtidrivers.com/index.php?s...207&hl=1860 and as far as i'm aware he hasn't had problems yet. Impressive torque with standard valves too I think.

[christopher 5 1 Cars]

No need to be amazed I don't think. It's the same internally as the Diesel (77mm) and TU5 (78.5mm) blocks. The guy that bored this one has a competition engine history that most engine builders might aspire to, including some very famous drivers at the peak of their careers. If he's happy, i'm happy.

 

TB 205GTi has run a TU5 block with 81mm (16v) http://forum.205gtidrivers.com/index.php?s...207&hl=1860 and as far as i'm aware he hasn't had problems yet. Impressive torque with standard valves too I think.

 

Yeah it was nice. We had a rumble on the motorway. Compression was way too high though.

 

It also had a 90mm crank though

Edited December 29, 2006 by christopher

[TB_205GTI 1]

Yeah it was nice. We had a rumble on the motorway. Compression was way too high though.

 

It also had a 90mm crank though

 

 

90mm steel crank from Farndon Engineering. customized EW10 rods, 81mm forged pistons. 177Bhp and 190Nm, ported throttlebody, ported head, but still std. valves. 283 deg cams with 10.4mm lift (If I remember correctly), Supersprint 4-2-1 manifold, 200cells sportcat. 2.5" homebrewed exhauts system with BIG mufflers to keep the noice down. Compression wasn't an issue on it, maybe the dynamic was too low for the cams?

 

Unfortunately the guy who bored the block didn't quite use the time needed - it suffered from a heavy oil consumption once the revs was above 4.500

 

When Chris and I had the little rumble on the motorway, it was not mapped properly - thus running too rich. The remap really made a huge difference, not on the max power/max torque, but it felt A LOT more responsive and strong. If I had kept that car - TB's would be on it by now, I almost got some original 106 Maxi ones for peanuts The std. inlet is beginning to be a limit on a 1860ccm engine.

 

EDIT: here is a picture of the walls when I bought the engine..

 

Edited December 29, 2006 by TB_205GTI

[welshpug 1,657]

177Bhp and 190Nm,

 

The std. inlet is beginning to be a limit on a 1860ccm engine.

 

blimey!

[Sandy 191]

I was very sceptical when you posted the spec, but the results were certainly impressive! Honda B16 pistons are 81mm and come up on ebay alot, hmmm.

[TB_205GTI 1]

I was very sceptical when you posted the spec, but the results were certainly impressive! Honda B16 pistons are 81mm and come up on ebay alot, hmmm.

 

The pistons are not expensive, nor are the rods - but the crank..

 

I have several images of the pistons if you like?

[christopher 5 1 Cars]

The pistons are not expensive, nor are the rods - but the crank..

 

Hows about a groupbuy at 2 grand a pop

Edited December 31, 2006 by christopher

[sorrentoaddict 1]

cheers guys, thanks for the info. One more Q:

 

what is the best budget option for a longer-stroke crank

for this engine (TU3 Iron block) ?

 

 

Thanks

 

 

AG

[Sandy 191]

The TU5 crank is 82mm stroke, at this rate you might as well buy a complete TU5 bottom end, they are cheap as chips out of 306/ZX/Xsara etc.

[sorrentoaddict 1]

Thanks for that info, Sandy !

 

Actually one of my mates is stuck with a cast-iron TU3

and decided to "build it up" to 1,600 or possibly more

cc, with a TU24 inlet plenum & camshaft, some serious

head work, and a higher C.R. as a result of the capac.increase.

 

I hope it will be a nice engine at the end of the day.

[Sandy 191]

Should be, the TU5 has a slightly lazy lope compared to the smaller TU's, but i'm sure longer rods and/or slightly bigger bore might overcome that.

[sorrentoaddict 1]

I always tell him that 150cc extra capacity is often not

so important as the overall character of the engine (as

it won't be a race engine anyway), but he is a kind of

a "capacity freak"..

 

Just a thought:

as the chamber/valve/port arrangement of the TUs resembles

a lot the legendary FIAT DOHC engines (132, Ritmo TC, Lancia Beta etc..),

and these engines are also known to be much "sweeter" in their short-stroked versions, I can see an interesting background in what you are saying - about the TU5 being "lazier" as a character.

[Sandy 191]

The different natures of engines is something I take a great deal of interest in. It's why I prefer the XU7 to the XU9! Not always that scientific either, for example the D16 in the series 2 Honda CRX has an infectiously revvy nature, at odds seemingly with its geometry.

[sorrentoaddict 1]

I think I see where are you getting at,

but if it's rod/stroke ratio that you are referring to,

it is often a prejudice that a lower rod/stroke ratio

creates un-revvy engines.

 

on the contrary, the forceful "breathing" of such

engines often makes them (other factors allowing)

very "explosive" when speaking about willingness

to rev (piling-up of revs in a quick manner).

 

whereas high rod/stroke ratio usually gives engines

that are "happier" at high revs, but it takes them (comparatively)

longer to get there (lazier).

 

I agree for the D16 engines, they are really exciting.

[Sandy 191]

It was thinking more of the 75x90mm undersquare that is extraordinary for it's nature, but the R/S ratio is low at 1.52. There's alot to do with cam timing as well, how it phases with the piston acceleration.

[christopher 5 1 Cars]

Just a thought:

as the chamber/valve/port arrangement of the TUs resembles

a lot the legendary FIAT DOHC engines (132, Ritmo TC, Lancia Beta etc..),

and these engines are also known to be much "sweeter" in their short-stroked versions, I can see an interesting background in what you are saying - about the TU5 being "lazier" as a character.

 

Hmm I'm not sure I see so much of a similarity. But the 2.0 is pretty lazy for sure in its standard single carb or injection format

 

Actually one of my mates is stuck with a cast-iron TU3

and decided to "build it up" to 1,600 or possibly more

cc, with a TU24 inlet plenum & camshaft, some serious

head work, and a higher C.R. as a result of the capac.increase.

 

I hope it will be a nice engine at the end of the day.

 

Sounds interesting. Keep us updated

Edited January 4, 2007 by christopher