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Author Topic: Mark's Polo GT Hillclimb Car  (Read 1175 times)

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Offline Tav

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Mark's Polo GT Hillclimb Car
« on: August 18, 2012, 12:28:37 am »
Goal & Background

Project Goal
The goal is to build a car to compete in the 2012 Scottish Hillclimb Championship.  I will be entering into Class A1 Road Going Production Cars up to 1400cc.  This class allows for some limited modifications to be made in an attempt to keep costs down and competition close.

In its current guise the Polo wouldn't stand a chance against the other cars currently competing in A1.  These include: a Vauxhall Nova 1.4SR running Webber Twin 40's and a very well spec'd Hillman Imp with an 1100cc screamer in the back. Both cars have outputs the right side of 100bhp and are well piloted.  Being a "free" car I am fortunate to be able to spend a bit of cash on the car in an attempt to make it competitive.  I'll be overhauling the brakes, suspension and attempting to squeeze a few more horses from the little 8 valve motor.  The Polo has some strengths that we are going to play to. 

I've always wanted to drive competitively but never had the budget for karting or circuit racing.  After spectating at the majority of hillclimbs last year and watching on as Stuart competed in his Integra Type R I thought this could be just the ticket...


A little bit of history...
I was gifted this car from a good friend who had it stored in his garage for the last 3 years. Ross is getting stuck in to help with the build as is Stuart, who also previously owned a couple of Mk3 Polo G40's.  We were all once Polo mad (unusual choice I know!), the guys have great enthusiasm and provide a lot of support, banter and brawn.   

Here are some photos of the car way back when in 2007/2008!





Below is a couple of photos and some spec. of my original Polo GT Coupe that I had a few years ago:
  • BBS RA 14x6J
  • Toyo T1R 195/45R14
  • H&R 60/40 Cup Kit
  • 256mm Corrado G60 Brakes - way over the top but great fun with 75bhp on tap!
  • OMP Velocity Suede Wheel
  • Quaife Gearknob






Here's a couple of Stuart's second G40 - this thing was properly quick for what it was...like bye bye Subaru Impreza quick...:



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Offline Tav

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Re: Mark's Polo GT Hillclimb Car
« Reply #1 on: August 18, 2012, 12:29:34 am »
Removal Men

Having sat for 3 years the Polo needed to be persuaded to step back outside.  A couple of hours of chapping away at seized brakes saw it exhumed...



Once out of the garage it was time to get the car loaded onto a trailer and transferred to its new home.  The trailer below normally tows a full blown race spec. Honda Integra Type R.  One of the benefits of the hillclimb community is that competitors really help each other out off the track. 



The Honda Accord Type R tow car made light work of pulling the Polo and we were soon at my rented garage 20 miles from home...not ideal but much cheaper than renting in the city, there's electricity, running water and a Subway near by...yum!  It also looks like we didn't hang around when it came to removing some weight from the car...


Offline Tav

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Re: Mark's Polo GT Hillclimb Car
« Reply #2 on: August 18, 2012, 12:30:17 am »
A Statement of Intent

Here's one of the first deliveries I made to the garage.  It's amazing what you can fit into a Clio 182 Cup with a little bit of imagination.  Can you tell what it is yet...?




One day I'm moaning that pukka race seats never come up for sale second hand.  The next day I get a call from Stuart telling me there is a Recaro Profi SPG for sale on the Integra DC2 forum and to top it off the guy only wants £220 for it delivered!  I couldn't believe my luck and literally ripped his hand off for it.  These seats normally retail at over £600.  We'll be mounting it to the floor using Polo Performance Parts Bucket Seat Mounts.  It improves safety, makes the car easier to drive flat out and it saves a lot of weight!



Here's the real statement of intent below.  A Dbilas Dynamic 40mm DCOE pattern inlet manifold from Germany.  Just right for fitting some 40mm individual throttle bodies I'd say...



...what have I got myself into...

Offline Tav

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Re: Mark's Polo GT Hillclimb Car
« Reply #3 on: August 18, 2012, 12:31:02 am »
Inspiration

Time to share some inspiration I think.  I've included a video from each of the 3 venues that make up the Championship to show folks just what the Polo will be getting used for.

Doune

Generally regarded as the scariest/fastest/craziest course of the year watch as Graeme Wight Jnr. threads his highly modied Imp up the hill in the video below:

GW Jnr. Hillman Imp Flat Out

If you want to see something totally unhinged watch as he then pilots his V10 single seater up the same skinny stretch of tarmac.  This video is not speeded up:

V10 Predator at Doune


Forrestburn

My favorite track as a spectator.  Ballsy at the start then gets more and more technical as you go.  Here we have Clark pedaling his BMW e30 318 to a class record followed by the Integra that normally sits on the trailer that was used to tow the Polo:

Clark Sutherland BMW e30 Class Record

Nez B Class Integra Type R

Fintray

Our local course and it's only 10 miles away.  It's the shortest too comprising of only 3 bends.  Don't let that fool you though the first one is a tricky double apex...or single apex...or triple...depends what you make of it!  This course favours power and traction as you accelerate out of each tight turn towards the next.  I've lined up a 16v KAD conversion Mini for this one, great noise!

KAD 16v Mini

Offline Tav

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Re: Mark's Polo GT Hillclimb Car
« Reply #4 on: August 18, 2012, 12:32:48 am »
Jason Moyle Racing

Todays update comes courtesy of Jason Moyle Racing. 

I might have mentioned earlier in the thread that my competitors all have some tasty under bonnet mods and that the Polo would need some extra horses to stand a chance.  I decided that throttle bodies would give the required bump in performance and provide an interesting project to work on.  Throttle bodies of course present a significant financial/time investment; one that can only be fully realised if they are breathing through a well prep'd cylinder head. 

Whilst I would love to DIY port the head I just don't have the time or kit.  Enter Jason Moyle; who I came across on Club GTi. 

Here's the Polo cylinder head strapped down onto the flow bench for testing



The light blue graph shows a standard 1300 8 valve Golf head.  The green graph shows this head ported to flow better.  The dark blue graph shows the standard Polo GT head. 

The Polo GT head matches the modified Golf item at low valve lift.  The Polo then begins to out perform the Golf in the mid-range due to having a bigger inlet valve.  Flow restriction caused by the standard nature of the Polo head chokes flow at higher lifts...what does mean?  It's a good starting point, but Jason can see room for improvement!



After the base readings were taken it was time to inspect the valve and inlet port.  I'm told the shape of the valve is 'horrible', the short side of the port is 'poorly shaped' and the throat is way to small for the size of the valve.  It all sounds pretty negative...but it isn't!  All of these areas will bring improvements to flow and thus performance when worked on.  She's got potential!



Even though he has other work on Jason couldn't resist opening up the venturi and de-lipping the back of the valve; just to see what sort of gains can be had.  This resulted in a 6cfm peak gain and 5cfm spread across a wider range of valve lifts.  I think it's great to see what a little bit of work can gain.



Absolutely delighted with what will come and Jason's proving a pleasure to work with. Regular updates via text message and a in-depth explanation of whats going on.  I'll keep the thread up to date as it comes along!

Offline Tav

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Re: Mark's Polo GT Hillclimb Car
« Reply #5 on: August 18, 2012, 12:33:40 am »
Take a Seat
Cylinder Head Update #2

Following on from the last cylinder head-centric update I can report that Jason's been busy and had the cylinder head away for machining.  I received a text message accompanied by a couple of photos mid-Fajita-cooking.  Almost burnt the chicken!

Below is a photo of the head as it was when it arrived at JMR.



...and here's the results of the valve seat machine work.  The seats have been cut with 3 angles in an attempt to improve flow at large valve openings.  The lead in edge as been cut back in an attempt to de-shroud the valve during initial opening.  This should have a positive effect on flows in the low-mid range:



Of course any improvement to the cylinder head needs to be verified by readings from the flow bench.  The pink line in the graph below illustrates the 3 angled seat's positive effect on flow; with an obvious increase at the larger openings.  We're not seeing much of an advantage between .300 and .400 which Jason suggests is because it now has a bigger appetite for air.  Opening the throat and venturi should provide that and will be be the next job!  Jason predicted an increase of 6CFM from those modifications.

[

I'm really starting to trust his experience now and I'm confident that'll be the case.  Can't wait to find out!

At this point we've decided to aim for 70CFM.  A standard Golf GTi head with a 40mm valve makes 72CFM and an easy 110-112bhp.  We're already up from 55.8CFM to 62.5CFM and still lots more to do.

I've acquired another GT head to use for parts.  Apparently the valves need a lot of work so it'll be easier to test knowing there are spares.  Never know it might become Evo II.

Offline Tav

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Re: Mark's Polo GT Hillclimb Car
« Reply #6 on: August 18, 2012, 12:35:20 am »
There's more updates to copy over from my original build thread on Club Polo but I'll leave these to settle for a couple of days.  Already a lot of work has been and gone and hopefully some new updates soon.  Hope you've all enjoyed reading so far!

Offline Tim Moll

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Re: Mark's Polo GT Hillclimb Car
« Reply #7 on: August 18, 2012, 01:02:00 pm »
Great read so far mate and welcome to the forum  ;D

Offline Tonyb

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Re: Mark's Polo GT Hillclimb Car
« Reply #8 on: August 18, 2012, 02:41:24 pm »
Good write up, looks like it's going to be a fun project. Those Polo's go well especially with a super charger!! The N/A engine should be a screamer, I guess they are fairly short stroke?

Offline Tav

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Re: Mark's Polo GT Hillclimb Car
« Reply #9 on: August 18, 2012, 06:01:07 pm »
75mm bore and a 72mm stroke, so the right side of square for revs.  She'll need to rev to make the power.  Just found out the 1400c 8valve 106 in my class is making 140bhp...eeek.  Jason and I set our sights a fair bit lower on the standard bottom end.

Offline Tonyb

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Re: Mark's Polo GT Hillclimb Car
« Reply #10 on: August 18, 2012, 07:38:46 pm »
Thats nice and over square, there is no reason it shouldn't make 140+ bhp from what I can see. I'm assuming the bottom end is different to the 1600/2000 bottom ends then if it's a worry.

Out of interest the std 8v cross flow engine makes 101bhp (I was looking today) as I have a plan  ;) so it's no great leap of faith to expect that a well sorted 1400 is going to make some good power. The more they rev the more power as long as you get enough flow - your going to need some bigger valve though, those don't look like they are right for the job! Will the valves from the bigger engines fit?


Offline Tav

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Re: Mark's Polo GT Hillclimb Car
« Reply #11 on: August 18, 2012, 08:38:02 pm »
With my budget for the first year we decided to stick with standard valve sizes.  With G40's (same cylinder head I believe but more written about them) stock is 36m/29mm.

Jabbasport do a 31mm exhaust valve and you can use a 33mm Golf item as well.  The material between the valve and the spark plug can get a little on the thin side though.  Though that benefits a F.I car I don't think you'd see much gains on a N/A motor? 

Not sure how much room there is on the inlet side or if there is a 38mm valve available, I'd assume this would be the ball park for next size up? 

Of course with a rebore from 75mm to 77mm and a jump from 1272cc to 1341cc there would be a little less valve shroud...then it'd perhaps cope happily with bigger valves......forged pistons are readily available for the G40 in this size but not the GT as far as I am aware.  If I got some made, as well as allowing for more displacement and lighter weight etc, they'd potentially let me bump the compression.  The GT has a flat cylinder head so redesigned pistons could help with increased CR and maintain valve clearance with deeper pockets.

It sounds like I am talking myself into stage 2 engine build with a reworked head and bottom end.  Would then just need to work out what the bottom end would take revs wise on the standard crank as German steel would be getting into silly money.  That might then lead us to the door of 140bhp...maybe...?

Offline JMR

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Re: Mark's Polo GT Hillclimb Car
« Reply #12 on: August 18, 2012, 10:54:34 pm »
Hi Mark. .great to see you here...welcome aboard!

I'll catch up proper very soon.

Offline Tav

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Re: Mark's Polo GT Hillclimb Car
« Reply #13 on: August 18, 2012, 11:02:59 pm »
Look forward to it Jason.  Was marshalling today and found out a competitor is rocking 140bhp from his 8valve Peugot and  700kgs...oh dear!

Just trolled through some German websites Tonyb on the back of yours question.  KWL motorsport in Germany offer valves in following sizes:

Racetrack (circuit) - 38/32
Long haul (endurance?) - 37/32
Mountain/Slalom (hill climb) - 37(38)/32
Standard upgrade - 36/31

Small gains in inlet size vs. larger gains in exhaust size again.  Good numbers to have written here for future reference perhaps.
« Last Edit: August 27, 2012, 12:00:21 pm by Tav »

Offline Tav

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Re: Mark's Polo GT Hillclimb Car
« Reply #14 on: August 27, 2012, 12:01:50 pm »
Restoration

As much as I'd like to concentrate on adding go faster bits there is a fair bit of restoration required; the car is 19 years old after all.  I've collated a lot of bits and bobs into this update.

Here we can see the rear beam after it came back from sand blasting.  The beam had a very rough finish, I think they used quite aggressive media, but it worked none the less:



Beam painted up with satin black spray on Hammerite.  Key words there being: satin and spray.  No matte, no gloss and certainly no brush strokes on this car!  Fitted some very firm G-Lader site rear beam bushes supplied by Polo Performance Parts.  My top tips for fitting:

  • Chill bushes in freezer before fitting (thanks Pete)
  • Wet & Dry sand the inside of the beam where the bushes are to be fitted
  • Use spray on lube - I had some 3in1 silicon to hand
  • Press in using g-clamp or bench vice making sure to keep the bush square
  • Tap home with a mallet.  Using a mallet from the out set will not work, you've got to press them!



Other assorted parts.  Stuart and I sandblasted these our selves at Donald's; another hill climb competitor with a 900BHP Evo and a suitably well equipped workshop.  Once blasted we treated them to primer and satin Hammerite.



Sandblasted VWII G40 carrier.



Primed and painted in satin silver.



Similar treatment for the G40 calipers.  Also fitted new seal, dust covers, sliders and rubbers from Bigg Red.



Borrowed a proper brake hose flaring tool from a local chap.  He gave me a quick 5 min lesson and after a few practice shots I think I'm getting the hang of it!



No I need to get all of these parts back on the car.  Seriously considering getting a blaster as well, quite satisfying restoring parts and some are getting more difficult to find new or in good condition.

 

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