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Author Topic: Mk1 GTI DX SET UP  (Read 1565 times)

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Offline Markg

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Mk1 GTI DX SET UP
« on: February 14, 2013, 09:16:21 am »
Hi, I'm new to the forum, my mate Tim Watson has just had his 16v head done with you and is very happy with the results, so was i that thing a little rocket.

I have a mk1 gti dx which i have been doing a few mods on lately: light diy port and polish, polished valve dishes, 3 angle valve seats, ashley 4 branch, 16v throttle body, 16 v WUR, piper 270 cam, vernier pulley, minimal head skim. I have just a few questions with regards to set up, the car is just for enthusiatic road use on those infrequent sunny days and general pottering:

1. Is there benefit from slight timing alterations or just a trade off between top/bottom end (currently bang on tdc)
2. What is the optimal ignition timing for performance/ smooth running with these mods ( currently 6 degrees btdc)
3. I have read a lot of controversial lit around air box drilling/mods, in your experience are there any quantified gains from some work to e airbox? Currently standards with a k&n panel filter

Interested to hear anyones thoughts

Mark

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Offline chrismc

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Re: Mk1 GTI DX SET UP
« Reply #1 on: February 14, 2013, 10:33:18 am »
Hi Mark.

Welcome along

With ignition timing, I'd suggest trying adding advance just until it pinks then back it off slightly. You should get a wee bit more if the head has only had a little skim. There is no ideal setting for a particular set of mods, you just need to experiment.

For the airbox, a few little holes really won't achieve anything. If you open out the outer side & custom fab a decent cold air feed you might gain 1 or 2hp & beefier induction note (I did Tims airbox)

Cam timing I always used to set to give equal lift on overlap at TDC as a starting point. Advancing it a degree or 2 from there would stoke up the mid range. Ideally you want it on a dyno to perfect that & also tweak the fuelling via the 16v WUR. My 8v never ever benefitted from retarded cam timing
1995 BB1 Honda Prelude 2.2 VTEC track hack
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Offline Markg

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Re: Mk1 GTI DX SET UP
« Reply #2 on: February 14, 2013, 01:11:42 pm »
Thanks Chris thats some good info, I've got a session on the rollers booked at Clive Atthowe as am over in Norwich so will have a play there, how can you tweak the WUR? Is there an adjuster somewhere?

I might have a play with the air box :)

I have the stardard exhaust from manifold back, do younthink this is too restrictive, i dont want to much noise and am trying to keep the look standard?

Offline Tim Moll

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Re: Mk1 GTI DX SET UP
« Reply #3 on: February 14, 2013, 07:16:16 pm »
Hi Mark,

Welcome to the forum  :)

There most certainly is an adjuster on the 16v WUR, if you remove it from the alloy mounting on the block you will see a brass cap on the back.  What you need to do is clamp it in a vice or even better in a pillar drill and very carefully drill a hole in the centre of it.....I usually use a 7 or 8mm drill (whichever is sharpest at the time)  Behind this brass cap you will find a screw that you can adjust with an allen key to alter the control pressure. 

The exact setting will be dependant on the tune of engine and can be a little trial and error on the rollers.  With the air metering head that will have been standard on your car you will typically find that the fuelling will start to run lean at the top end....hence the need for adjusting it slightly, but adjust too much and it will be too rich elsewhere!! 

The Slick50 boys of old use to fit 1600 air metering heads as the cone in these is significantly different to the 1800 items and provides a better fueling profile for modified cars, however these ran a far higher level of tune than yours and I'm not certain what benefit it would give for you if any at all!  I have one of these fitted in mine but I am running a 1900 bottom end with a big valve head, 11.5:1 CR and 300deg cam but it certainly leveled out my fuelling  ;D

Here's the two air metering heads side by side....the bigger dia one is the 1600 one...



And here is some AFR data from dyno runs with the two different air metering heads to show the effect on fuelling profile and also the effect of control pressure  :)



Hope this gives you a little food for thought.

Tim
« Last Edit: February 14, 2013, 07:24:38 pm by Tim Moll »

Offline Markg

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Re: Mk1 GTI DX SET UP
« Reply #4 on: February 14, 2013, 09:20:19 pm »
Cheers tim, i had read about the 1600 metering heads providing better fuelling, and thanks for the tip on the WUR adjustment,i shall prep that For the rollers. The 16v WUR was a bit of a fluke really as i had fuelling issues on my first run prior to the mods, I had 5 bar control pressure! Popped on the 16v WUR and control pressure is know around 3.75 when warm and drops with the vacuum advance as you throttle hard so will be interesting to see if this will suffice.

What sort of power are you getting out out yours Tim I bet its a bit of a rocket :)

On another subject I have just done an oil and filter change, started and have low oil pressure and oil is not getting around the engine, tried giving a little rev and no joy so switch off sharpish, i thought is may have been a dodgy filter so i put some fresh in the old one and started her up and still the same issue, i have never had this on any car, possible hydraulic lock? Or feed pipe blocked??? Typical!

Offline Tim Moll

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Re: Mk1 GTI DX SET UP
« Reply #5 on: February 14, 2013, 09:36:26 pm »
Hi Mark,

Yeah mine goes pretty well  ;)  There's a build thread on here http://jasonmoyleracing.createaforum.com/customer-cars/tim-moll's-red-mk1-trackcar/  It's producing 155bhp so a fair bit of fun  ;D

I don't tend to bother with the vacuum connection on the 16v WUR TBH I just leave the outlets on the WUR open to atmosphere as with them connected I have found previously it overfuels at top end!

With regards to the oil pressure problem I have had this before with an old engine.....but only when I have drained and left engine for a little while before filling it up!  I'm not sure what causes this but suspect it's either a worn pump or worn main bearings but not certain....what I do know is whenever I build a new engine I fill the pump with grease and this prevents this issue on initial startup...however this doesn't help you much unless you feel like whipping the sump off!

I actually made a tool up that attaches to an electric drill, you pull the dizzy out and drop this in the hole where dizzy normally lives and it slips over the drive on the oil pump and a quick spin of the drill and hey presto......the other solution which might get it sorted is whip the plugs out and disconnect the DIS plug to the dizzy and crank away until you get pressure, ideally do this while jumping from another car so you have plenty of cranking speed and don't flatten the battery  ;)









Hope this helps a little.

Tim
« Last Edit: February 14, 2013, 09:48:27 pm by Tim Moll »

Offline Markg

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Re: Mk1 GTI DX SET UP
« Reply #6 on: February 14, 2013, 10:58:51 pm »
Nice tool ;) thanks again tim, i might whip of the sump to check pick up gauze anyhow I've heard these can clog sometimes, I'm hoping its a simple fix, the engine was still hot at this point and no previous issues so should be mechanically sound, i might even pinch your tool idea!

155bhp too, wow thats awesome, mine was 102 at flywheel pre works, we will see how my handy work bears up
« Last Edit: February 14, 2013, 11:00:37 pm by Markg »

Offline Tim Moll

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Re: Mk1 GTI DX SET UP
« Reply #7 on: February 15, 2013, 12:07:07 pm »
Mark if you are struggling let me know and I can always stick the tool in the post to you if you need to borrow it.

Cheers,

Tim

Offline Stooza

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Re: Mk1 GTI DX SET UP
« Reply #8 on: February 15, 2013, 12:32:06 pm »
And this is why this place is so great! Welcome Markg, get some pics up buddy  8)
Mk2 2.0 16v GTi (built for track day fun)
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Offline Markg

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Re: Mk1 GTI DX SET UP
« Reply #9 on: February 15, 2013, 12:34:23 pm »
Cheers Tim, thats very helpfull, i will have a play today, i will get some pics up later, i have baby duties to attend to :)

Offline JMR

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Re: Mk1 GTI DX SET UP
« Reply #10 on: February 15, 2013, 07:44:17 pm »
Hi Mark

Welcome aboard!  ;D

Yeah Tim appears happy with his 16v head...goes ok apparently.. 8)

Ive found a 4hp gain back to back on the rollers with a modded air box.

Ignition timing can be usefully increased to 8 degrees on idle.

Cam timing needs checking via the lift @ tdc method to ensure it's right...front pulleys can be out so use the flywheel as a guide, but the true tdc needs to be found off a piston through a plug hole with a dial gauge. Most cams run better with some advance...more lift at tic on the inlet than the exhaust...15 thou is a good starting point measured off the cam buckets.

I've done road spec 1800's with a 268 cam and mild head work making 108 at the wheels..
132 at the flywheel...so you don't need mega specs for road fun.

Offline Markg

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Re: Mk1 GTI DX SET UP
« Reply #11 on: February 15, 2013, 09:11:34 pm »
Great stuff, I confirmed tdc from the piston during the build and then the cam as you say using the disk on the crank. Interesting on the air box, i will get something done, ae there any picturesnof modded boxes that anyone has? If i got anywhere near 130 flywheel i would be ecstatic! Thanks for the info:)

Offline Tim Moll

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Re: Mk1 GTI DX SET UP
« Reply #12 on: February 15, 2013, 10:20:44 pm »
Mine is modded to the max...pretty much the whole of the underside is cut out, however this itself brings it's own problems as the inlet charge was VERY hot when I first had it on the rollers as it was sucking hot air in from the engine bay!  For this reason I made up an aluminium heatshield that wraps underneath the whole of the airbox and up the side, at the same time I re-located the battery to behind the passenger seat and fitted a large cold air feed mounted in the grill to feed the enclosure.










Offline Markg

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Re: Mk1 GTI DX SET UP
« Reply #13 on: February 16, 2013, 08:29:07 am »
Ah, i see what you have gone for, looks like a good job, my issue is trying to keep the standard look as it a campaign and a fairly tidy one i was thinking of an addition feed somehow hidden but dont know how i will achieve this :) car look mint Tim do you track it? Mine is purely a road goer i wouldn't mind another to track but they are getting pricey now! Maybe a mk2 for track to keep the cost down for me

Offline Tim Moll

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Re: Mk1 GTI DX SET UP
« Reply #14 on: February 16, 2013, 04:36:28 pm »
Yep this ones primarily for the track, although it is also road legal, just need to get my arse in to gear and get an MOT on it!

I've got a couple of Campaigns as well, so know what you mean about keeping ity standard looking....one of mine is fitted with a GTI Engineering RE1900 so goes well while keeping the standard appearance  ;D


 

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