[trackday_prep] My 1/4 Mile And Trackday Project Car

[pip470 61]

Hi everyone, im in need of some advice, I went to santa pod on the 12th and put in 13 runs. Ive had a silly pub bet that i can beat his 2.0l xr3i. His best time is 15.3. The best time i could put in was 15.79 and that was my very first run. After looking through the slips it was becoming aparant that the best runs were the first one and the ones where the car had had a big break ie after a 2 hour dinner break and then again just before the track closed. The heat of the engine was severly affecting the engines output. The rear has been stripped already but i still have the carpet door cards and alot of things i dont need such as noisy fan and may aswell do away with the heater matrix. My question is Do you think i could lose .5 second with weight reduction? This is just a fun car so dont want to spend any money really but i want to win this race. I also did all the usual dropping the front tyre pressures and raising the rears. Can you think of any other suggestions i could try. Sorry for such a long thread too but can some one tell me when i should be changing gear. The rev limit on this car according to the tacho is 7000 so i was changing just before this. Im i wasting time by even taking it to 7000? Oppinions much appreciated

[smckeown 1]

According to the cartest 2000 simulator, a pug 1.6 GTI needs to lose 80kgs to reduce the 1/4 mile by 0.5 secs.

[Gtiracer 0]

depends on the engine really as some can tail off in the rev range that high up and may be more effective to change earlier, best way - PRACTICE.

 

Get out to a quite area or airfield and test your times on a stopwatch and see at what revs give you the best time - get to know the car of course lose more weight if you can and you should beat him easy.

[GTI6BOY 29]

What gtiracer said.

 

you will gain half a second with a good start.

 

Hold the revs at about 5k when the lights go drop the clutch and make sure you change about 6.5k, this is usualy the peak point of the power.

 

dont miss any gears and you will do it

[pip470 61]

Thanks for the replys, i dont ususlly miss gears and i only get to third before the end of the run. Can anyone give me any tips on getting the engine cool again the inlet manifold was just so hot and that cant be good. I had the bonnet open and pushed it to the start line with the engine off but it made little differance

[GazRallye 0]

maybe putting a manual rad fan switch would help cool it as you can leave the fans running

[pip470 61]

Super idea, i take it you leave the engine running then so the cooler water circulates rather than just sitting in the radiator. I like that mate. Any more please?

[Rob_the_Sparky 9]

Tune the engine right. Are you using SUPER/OPTIMAX? If so then play with the ignition timing, most cars are retarded and correcting this releases power. If on unleaded then swap to super/optimax (preferably Optimax or Tescos 99) then do the ignition timing.

 

Make sure the air filter is clean.

 

Cheak the exhaust downpipe split is a) present and has not collapsed (it can partially block the pipe).

 

Rob

[Ahl 4]

Is the car a 1.6 or a 1.9 or something else?

 

I think a 1.6 will struggle to get down to that time.

[Richie-Van-GTi 73 2 Cars]

Make sure you have a good clean cold air feed, also take the oil breathers off the intake and into a catch tank (pop bottle works well) then block the holes off on the intake. Have you tried with slightly higher front pressures than you were running?.

[16v205 9]

Whats your 60ft times?

 

Rich

[pip470 61]

Whats your 60ft times?

 

60ft ET MPH Time between runs(mins)

 

2.2 15.79 84 first run

2.8 16.45 85 5

2.5 16.33 83 7

2.4 16.19 84 5

2.6 16.24 84 50

2.3 15.82 85 180

2.4 16.18 82 25

2.5 16.02 85 25

Can i ask does this tell you anything?

 

You can see when the car had a big long break it seemed to go better ie first run and then after dinner. The clutch didnt like the launches one after another either. It didnt seem to bite sharply which is understandable.

 

To answer some of the other questions I was using shell optimax, The exhaust is a magnex full stainless from manifold back and is in good condition, I removed the headlight as the knN is fitted right behind it so counts as a cold air feed. It is a standard 1.9 as far as i know other than the mods mentioned. I was wondering should i raise the rear end and drop the front as its on coilovers on the front. Raising the rear wont take long. Thanks for all your responses

[pip470 61]

16v205 any input on the 0-60 times?

[VisaGTi16v 1]

If this times are accurate then your starts are very good but I am sceptical.

 

At a number of sprints they have 64ft timers (no idea why 64ft). I always do ~2.64secs give or a take a hundredth or two as I am very consistent and consider myself a good starter. Thats with an mi16 engine and soft rally slicks. I have never seen a 2.2 in my modprod 2 litre class, some of the Escorts that are obviously rwd so better off the line and with 8+" rear wheels get into the 2.3's, its 4 foot more but that wont make that much difference

 

As well as the dubious low times, there is a massive difference. Were you trying different starting techniques, couple of them had big wheel spin etc?

[pip470 61]

Hi mate there straight of the time slips off santa pod they must be pretty accurate. I did have ggod starts really i think, could pretty much beat most things ie suburus, 2ltr novas but doesnt take them long to catch up with the extra power. The inconsistancy i was putting down to the clutch and the fact that im just starting out, i pretty much tried to keep to the same technique through out the day. I dont know what to say about you not seeing them times. maybe i could post my best timing slip. see what you think. cheers for your reply

[Baz 421]

You still haven't stated exactly what mods, what's been added/removed etc

 

Obviously as you say, you could lose a little more weight. Can't remember rightly, but isn't it better to stiffen the rear suspension, may help minimally in the weight transfer in the initial getting off the line, i may be wrong though.

 

Have you considered gear ratios too?

Edited May 28, 2007 by BazGTMi

[pip470 61]

raising/lowering and stifning softening are two seprate things. the rear has stiffer torsion bars and stiffer spax adjustable shocks. With raising the rear i am trying to get as much wieght forward as posible to aid traction. I think it will work.

The car has spax rsx suspension no interior apart from the dash and the seats and sunroof soon to be removed a standard engine 1.9 gti engine apart from KnN and full magnex exhaust system. Thats it really no other mods i can think off. Going to take the heater matrix out wednesday and plate the sunroof. Ill wait for good weather before i raise the suspension. Hope this makes sence. Cheers phill

[chris1986 1]

another thing i can think of is don't run wit too much petrol in. i usually have someone holding a couple of fuel cans. this allows me to safely run for a long time with under 1/4 of a tank. i just recently went with my 106 rallye for the first time, found you lose loads of time when you spin at first i found if i set off a little smoother my 0-60ft times dropped by .4 sec the rallye was getting on average 2.5 sec to 60ft

[hengti 2]

can't believe someone has suggested you dump the clutch at 5k..

 

anyway, got to agree with Visa - those are pretty impressive launch times!

 

if they're correct, you must be pretty accomplished at it; if you don't want to spend any money on modding it, i guess your best option is in removing weight - ?

don't think it'll make much difference in a straight line though

 

have you tried flat shifting?

[pip470 61]

well did most of the things i wanted, removed loads of the wieght, added a shift light to concentrate keeping the car straight and fitted a manual fan overide to keep the car cool. Tommorow is another test day so ill see what differance it will make. Still got some more things to do for the final race day next weekend too. wish me luck

[adriches 0]

How about...... smaller wheels?! Smaller rolling radius so same affect as lower gearing!

[inferno 1]

you mention lifting the bonnet at the front to cool things down...

 

this would work better if you raise the rear of the bonnet as it will lower underbonnet pressure and draw hot air out faster... possibly...

[pip470 61]

Well im back and i love my car even more now than ever, 7 runs and 300 miles at high speed, not sure what speed because my speedo stopped working but it made it and the good news is i did it. much the same as two weeks ago my very first run was the best with everything being really cool and the time was 15.28 @ 89 mph 60ft = 2.32 The weather was exceptionally hot too so that manual overide fan switch was well needed. What i want to point out though is i am amazed at this differance, i took out about 50kg of weight and the few other jobs as posted previosly and the car accelerates like never before. I know that its no secret about power to wieght ratio but now ive really got the bug, Might even go on a diet as 16.5 stone could be 12 and thats another massive wieght reduction there. Ive got a few more mods i want to do ready for this race next saterday so should get an even better time hopefully. Two weeks ago it was a three gear race but now i go through third and into fouth for about two seconds. maybe the smaller wheels will mean i get longer in forth as it seems changing to forth at the minute is a bit pointless but cant stay in third any longer. I like the idea of the bonnet too gona see if i can get some bonnet pins. On a different note the fastest front wheel drive car i saw there was a 550bhp turbo redtop corsa, 450 without nos, that ran a 12.5 amazing. So only 2.5 seconds to lose lol Just going to keep making changes and i though it would be a good idea to keep documenting the change and the time achieved. Thanks for all your advice keep the ideas coming and hopefully ill see some of you at the north meet tommorow. Cheers phill

[sutol 0]

Go on the last amber light and no racing starts, start off quick but try not to spin the wheels, 1500 to 2000 rpm should be plenty as long as you are on cam.

Change early from first, don't wast time using high revs as long as you are on cam when you drop it in second, it is sometimes better to leave it in third rather than grab a higher gear if you are near the finish line, but experiment with an earlier change in the last third of the track.

The best place to gain time is in the first and last quarter of the track, practice the start and gearchanging, you can loose precious time slipping the clutch, wheelspinning and being in the wrong gear going over the finish line.

Lower the suspension, pump up the rear tyres and remove the mirrors, make sure the windows are completely closed, then go on a diet or at the very least take a dump before the race, every little helps.

Everything else costs money so best of luck.

[pip470 61]

Just wanted to update this as its been a while and i didnt want to lose the thread. So Ive gone a little crazy with the wieght saving Ive removed the entire dash board and made a little one to house some switches and stuff, made it out of dimpled alluminium, carpet , all the door internals including the inner skin, Ive fitted the ally plate on the sunroof, moved the battery to the boot, fitted two cobra imola gts (will take the passenger one out when racing) 3 point harneses, removed the fuel tank and fuel lines from under the car in order to get a small ally fuel tank in the boot. So far i have only got one poly carbonate window in at the minute but will hopefull have a full set soon. I have raised the rear of the bonnet for cooling. And probably the biggest change was saying goodbuy to my faithfull 8v. Instead i have gone for the 1.8 16v because a zxara came up cheap. Its bolted to the 1.9 gearbox, ive fitted the gti 6 exhaust manifold and just bought some bike carbs. Hope fully next month i will have enough for the mbe ignition management and a fuel tank and pump. At least then i can hear the engine run. I will kepp this updated as i go along untill that day i can race it finnaly comes. Phill