Cf Airbox And Some Dyno Runs

[swordfish210 20]

After some deliberation i finally decided that my previous attempt at getting cold air to my air filter was, well.... pathetic, to put it lightly. Radical action was needed so i began putting my brain in to action to design and build a new cold air intake system.

 

 

The first thing i decided that was required was an auto bonnet as there wouldnt be enough clearance with the standard bonnet, and by some miracle of chance that very eveining a found a white auto bonnet for sale (thanks to KtKat) so £30 later and a trip to Warminster it was mine.

The next step was to chose a material for the box to be made out of. I initially thought of fibre glass but then decided that if i was going to do it i might as well go all out and i settled on carbon fibre. Luckily for me one of the lecturers at Wiltshire College (Steve Thomas) also works for Dymag and has all of the facilities to make carbon fibre components at his own workshop, so ater a quick discussion with him and a few bits of idea swapping the plan was fully in motion.

I had a final design for the airbox in a few hours and then added some measurements to it. I decided to have a 2 piece box sitting on top of the carb witht he filter plate sitting on top of the bottom section of the box and the box would be held togeather by rubber T-clips and a tube would supply air from the front of the car via an existing duct. (confusing i know but you will see what i'm on about later).

The box was relativly simple to make as you can see. The first stage was to cut some foam to the size required and then curve the edges so it would be much easier to lay the glass fibre underlay on to it.

 

 

I then cut 2 slots in to the bottom section and put some more foam in to them so the filter plate would have some clearance.

 

 

I then coated the foam in some gel coating so that it would be much easier to remove the foam from the mould when it was finished.

 

 

The next stage was the intake tube. This was going to be a small cylinder (approx 60mm long) sticking out the side of the box to allow a tube to be attached to it to supply the cold air. I made this out of a glass fibre mould streched over a piece of plastic tubing which happened to be the size i was after.

 

 

The next day i removed the tube section from it's moulding plate and set about cutting it to size and shape so it would fit on the front of the box.

 

 

When that was sorted i put a strip of plastacine around all of the edges and joins so that it would make the glass fibre easier to lay.. I then coated the moulds in some PTFE release agent and some wax so the whole lot would seperate when the time came (remember this bit for later :wink: ) I then cut some glass fibre to shape and coated the moulds in a black resin. I laid the glass fibre sheet on and pushed it to shape with a brush and some more resin.

 

 

The next stage was to lay on the carbon fibre sheet. Now this stuff is really cool and it doesnt require cuttin so it will go rould corners and folds. So after a lot of resin and a small roller i had a tight fit of carbon fibre sheet on my moulds.

 

 

 

The mould was put in an oven overnight to cure and was kept at a constant 50 c temperature. The next day i removed them from the oven and set about removing the foam from the finished product but....disaster!!!!!! The gel coat would not seperate from the carbon fibre, DAM IT! i had to settle for just cleaning all of the foam out and leaving the gel coat in. I then cut a hole in the bottom of the box so the air could get to the carb (quite importanat that ) and fitted the T-clips.

 

 

I fitted the box to the car and connected the tube and went to start it up and...disaster again!!!!! the car was running like an absolute bag of crap and wouldnt idle for toffee, it just stalled everytime i lifted off the throttle. I came to the conclusion that i had been sloppy when i fitted the box and had left some CF dust in it which had been sucked in to the carb on start up.

 

A quick visit to Curcuit Motors later and i had the car booked in for a carb strip down and clean up and a full rolling road tune up .

 

The car went in this morning for its tune and after a few hours the problem turned out to be a mixture if a blocked idle jet and a blocked fuel cut off sensor, There was also the small problem of poor throttle cable set up as what was full throttle on the pedal was'nt actually full throttle on the carb, so the car was now ready for its runs. It was tested initaly and the run came in at 81.6bhp with 80 ib ft of torque. But after some tweaking, a few new jets and some ignition timing resetting the final result was 86.9bhp at the flywheel and 87.8 ibft of torque.

The airbox proved to give a 2-3bhp gain on the rollers so i can safely say it was well worth the effort .

 

 

After a test drive home i can say i am well pleased with the way the car runs now, loads more power and torque and it just keeps on pulling at high revs ( i hit triple figuers on the way home from work)

[welshpug 1,657]

err, nice work, bit wheres the filter?

[bren_1.3 1]

looks very good. do you have any close ups of the finished item? what sort of carbon have you used? a 2x2 twill or just a plain cloth?

how many layers of wax and release agent did you apply?

did you use polyester resin or an epoxy resin?

 

sorry for all the questions. ive always fancied having a go at this!

Edited July 9, 2007 by brens_1.9_wide_arch

[swordfish210 20]

no probs, i'll try to get some close-ups tomorrow for you,

1: the carbon sheet we used was a 2x2 twill cloth (i think)

2: i applied 3 layers or release agent and 1 layer of wax, steve thought that it was because he put it straight in the oven instead of letting it dry for a few hours that was the cause of it sticking

3: i belive it was a polyester resin

 

hope this helps

[Jrod 7]

Are you not using a filter?

[djinuk 2]

is a decent increase from these aftermarket filters as i am still on standard airbox with filter but my xs seems to fly, ive had a recorded 117mph top end , and the bottom end is fierce for a 1.4 , but ive not touched the air filter side of things as ive not needed to , just a full exhaust, head rebuild , and looking after. Good Job you have done there btw, I think you should repaint if though and brand it, will look much neater

[RossD 44]

So you have a 4-2-1 manifold, a DGAS(?) carb and you are 1.9bhp up on standard?? I wonder if going back to the solex carb would make any difference?!

 

Nice job on the airbox though I'm thinking of making on for my TB's.

[RossD 44]

Ah, the car is an XT, does this originally have the 70bhp TU3 engine? If so thats a damn good gain

Edited July 10, 2007 by RossD

[swordfish210 20]

err, nice work, bit wheres the filter?

 

sorry that pic is a bit misleading, the filter is in there i just didnt put it on for that pic as i thought i would show how the box attaches to the carb

[swordfish210 20]

Are you not using a filter?

 

see above quote-post

[swordfish210 20]

is a decent increase from these aftermarket filters as i am still on standard airbox with filter but my xs seems to fly, ive had a recorded 117mph top end , and the bottom end is fierce for a 1.4 , but ive not touched the air filter side of things as ive not needed to , just a full exhaust, head rebuild , and looking after. Good Job you have done there btw, I think you should repaint if though and brand it, will look much neater

 

not really much power gain to be had by the filter, just a lot of noise. what do you mean by "repaint"?

[swordfish210 20]

Ah, the car is an XT, does this originally have the 70bhp TU3 engine? If so thats a damn good gain

 

nah it's gat the 80bhp TU3-A engine but it has covered 147,000miles without having the head off so it's getting a bit tired now. The guy doing the dyno tune said that the valve springs were getting a bit tired becuase they were bouncing like hell at 6,600rpm

[swordfish210 20]

forgot to show you that this is the duct on the front of the car where all of the air gets sucked in to

 

[Jrod 7]

Nice job on the airbox though I'm thinking of making on for my TB's.

 

 

I spoke to Sandy about it and he didn't think it was worth it. Plus the noise, you want the noise!

 

 

^^^ that intake looks cool.

Edited July 10, 2007 by Jrod

[trogboy 17]

I spoke to Sandy about it and he didn't think it was worth it. Plus the noise, you want the noise!

 

Didn't think it in what way? I know my under bonnet temps are pretty high in stop start traffic but probably close to atmospheric when on the move. Is that what you mean?

[Jrod 7]

He said it'll probably lose what it gains and it won't sound as good.

(this was a Euro rallye box, nothing fancy)

 

I trust his opinion so am going to stick to just filters.

Edited July 10, 2007 by Jrod

[swordfish210 20]

^^^ that intake looks cool.

 

yeah i do quite like it, should suck in plenty of air when it's on the move

[DaveW 6]

whats next then chap? new cam?

[RossD 44]

nah it's gat the 80bhp TU3-A engine but it has covered 147,000miles without having the head off so it's getting a bit tired now. The guy doing the dyno tune said that the valve springs were getting a bit tired becuase they were bouncing like hell at 6,600rpm

 

TU3A is 70bhp from the factory

So that is a very good increase, especially with the very mild cam it's got.

Edited July 11, 2007 by RossD

[christopher 5 1 Cars]

Thats a big scoop. Does the TU3S have a smallaer raidiator then the Gti? I don't think mine has room there..

[bren_1.3 1]

Thats a big scoop. Does the TU3S have a smallaer raidiator then the Gti? I don't think mine has room there..

 

base model TU's run smaller radiators than the euro rallye. on the XY engined cars the expansion bottle is located in the space where the scoop on swordfish's picture is.

 

Didn't think it in what way? I know my under bonnet temps are pretty high in stop start traffic but probably close to atmospheric when on the move. Is that what you mean?

 

are you still running the pipercross filter Adam? how was clearance with it regarding the master cyliner?

[swordfish210 20]

whats next then chap? new cam?

 

i'v got a head from a UK spec ralle engine (TU3.2 i think) which has got a kent cam in it and verner pully so i'm halfway through rebuilding that and then it's gunna be back on the rollers to have the cam timing set up. I'm hoping to break the 100bhp mark but it's gunna be tight.

[swordfish210 20]

TU3A is 70bhp from the factory

So that is a very good increase, especially with the very mild cam it's got.

 

wow i was allways under the impressiont that it ws 80 standard, thanks for telling me that cause i'm happy as hell now

[Anthony 1,003]

Apologies in advance for going slightly off-topic, but out of interest what did Circuit Motors charge for the rolling road time and what did you think of the operation down there?

 

Want to have a play around with the cam and ignition timing as I'm convinced that there's more to come from my engine, and they're localish to me (I'm assuming this is Circuit Motors near Castle Combe?)

[swordfish210 20]

no probs, the bill in total, which included a full strip down and rebuild of the carb, new gaskets and some jets, 5 dyno runs and a road test came to £260. I am really pleased with the outcome of the setup, the only critisism that i can think of is that the throttle was a bit stiff when i got tyhe car back but a spray of WD-40 cured that. I didnt get to see any of the dyno runs as i was stuck at work but he said he was only working on the car for a few hours in total. In conclusion i would recomend them to anyone as i think they did a top job on my car. Oh and yeah it is the one by castle combe