Tu Tuning, I Just Want 100Hp

[309jazzpanda 41]

Hey guys here to nag about my gtx (again). Basically its due a rebuild soon and i wouuldn't mind a little play while its apart, now a bit of research shows the 1400 ax gti had 100bhp out of the box and its a 1400 spi like the gtx, which is only 75bhp iirc.

 

HOW?

 

I'm guessing its all about valve size, i'd love an xs alloy block but think thats a pipe dream for now. So if anyone could help it would be great, i'm hoping something like an xsi head will work but again not sure whether they were spi or mpi

[dcc 855]

I am guessing it shares similarities with a 1.4 106 XSI which is quite impressive for its engine + weight. The gearbox makes most of the 'power' with its closer ratios.

 

For the money you could be lookign at, why not have a think about the tu5?

[welshpug 1,661]

gti was MPI, so used a different cylinder head.

 

easiest way to 100 bhp is the TU2J2 or TU3J2, or the TU5J2, these all use much the same cylinder head casting and camshaft profile.

 

or 120+ from a TU5J4 which is a little more involved as it needs the exhaust downpipe cutting about.

[allye 530 3 Cars]

Why do you say a ali block TU3S engine is a pipe dream? If you are taking the engine out anyway why not get hold of one? Theres always some one on here with one. If your looking for around a 100hp from a 1360cc TU engine stick some twin webers, lumpy cam and try and find a 4-2-1 and you will be easily around there if the engine is a good'un.

[Batfink 201]

106 rallye engine is 105bhp out the box...

[GeorgeXS 32]

Allye has a point, why assume a TU3S is a pipedream? I have one spare in the garage thats potentially for sale, make me an offer!

[309jazzpanda 41]

right good info guys but slow down with the codes, which engine is the tu5? or the tu2 etc. I'm guessing these are saxo vtr/306 and the like ?only know mine is a tu3 with spi and the 16v 106gti code is the 5j4, still learning the engines at the minute.

 

I thought the alloy blocks were like hens teeth you see

[MiniGibbo 142]

106 rallye engine is 105bhp out the box...

 

S1 = 100hp

S2 = 103hp

 

[309jazzpanda 41]

what are thoughts on bike carbs? see once the 309's done i'll be having to rebuild the engine in the 205 as its fubar, put my foot down the other night and instead of the oil smoke, it had a lovely black colour to it as well.

 

So i'm thinking whilst its being rebuilt i may as well do a bit of tuning

[rallyeash 155]

bike carbs can be good if there done professionally, if there bodged on with silicone conectors there s*it....

[MiniGibbo 142]

Read a write up in the latest "track driver" that basicully says bike carbs arent even worth mentioning there so s*it

[Batfink 201]

S1 = 100hp

S2 = 103hp

 

 

ahh ok. I could not be bothered to look it up...was just going on rolling road readouts from a few years back when just about every 1.3 on the day made 105bhp. Cannot remember if they had induction kits but I thought they were standard.

 

 

Read a write up in the latest "track driver" that basicully says bike carbs arent even worth mentioning there so s*it

 

Bike carbs are ok but need a properly designed manifold. Just like all carbs and throttlebodies.

[MiniGibbo 142]

I have no idea about the difference's but in the mag it said the biggest down side to bike carbs is balancing them..

 

Was a good read tbh.

[welshpug 1,661]

main issue is the rubber/silicone hoses most diy kits have, bolt them down properly and they will balance easier and better than jenveys and the like.

 

i would leave the standard induction on there till you can afford to do it properly

[309jazzpanda 41]

we've got a balancing tool we managed to acquire last year, its just a thought at the moment. I'll probably just rebuild mine to stanadard and have a play with the head unless i come across an xsi or rallye lump in the new year

[allye 530 3 Cars]

Read a write up in the latest "track driver" that basicully says bike carbs arent even worth mentioning there so s*it

 

I read this, enjoyed the throttle bodies/carb write up the previous month as well.

[MiniGibbo 142]

Yeah I didn't know anything about them and found the write ups really helpful.

[309jazzpanda 41]

got this months PPC and luckily its featuring a choose and fit bike carbs to your car, intersting read

[309jazzpanda 41]

Afternoon all, right been offered a vtr head and loom for pretty much no money, will this fit nicely on my 1360 single point or more to the point an alloy block. My theory is I get a light bottom end and nice big valves to flow the juices

[sam-barker 2]

why not just stick a vtr engine in?

 

I had a 205 XS which pulled 101bhp on the rollers, it had an SU carb fitted.

[kenp 3]

...I had a 205 XS which pulled 101bhp on the rollers, it had an SU carb fitted.

 

Nice... SU is an excellent carb, easy to setup too. HS6 (1.75") I assume? Where'd the manifold come from?

[309jazzpanda 41]

Because its cheap so just wondering if it will fit, what did you have done to your xs

[trogboy 17]

It will bolt on but the compression ratio will be very low due to the larger combustion chamber for the VTR head. When I say low I mean 8.5:1 or something and it'll probably make less than a standard TU3S. It's the same issue with fitting the TU24 (euro rallye) head straight onto a TU3 bottom end.

 

If you are looling to stay 1360cc you can get around it a number of ways but all are a compromise between effort, expenditure and results. Domed pistons from a 1360cc 106 XSi engine are reasonable solution but then you might as well drop the whole lump in. You can go budget and get a really heavy skim on the head but it changes the shape of the squish area in the chamber and leads to retardation of the cam unless you fit a vernier pulley which ups the cost.

[sam-barker 2]

The manifold was a bit of a bodge, it was how the car came

 

 

[kenp 3]

Some interesting flow angles there I'd have thought, but sounds like it worked well enough