Mark 4 VW 1.8T GTi Build - RallyCross - MF Class

Weather is looking good, so my plan this weekend is to get these babies put in, and get the rear ride height set. I know once the cage is in, they will need to be re-set, but at least it is forward progress.

Very interesting/entertaining thread... Curious to see what times you will have. Also curious what your budget for the build is.

Seems like you'll have to finesse the throttle a lot. I drove a couple turbo 4s with similar power on snow and they all would break free with boost onset resulting in having to back off the throttle until up to speed. Basically driving a 1 wheel drive car. Does your Golf have some sort of traction control? Also what's the plan with the diff. I'd sell some of them gearboxes and get a clutchpack diff, as discussed before, that would give you better control both throttle on and off as well as help on liftoff overseer.

Also, about unsprung weight: the job of the damper and spring is to control the oscillation of the wheel, the heavier you make that wheel the more work that damper is going to have to do to keep the wheel from oscillating. Brakes, being iron, weigh a lot. In aviation we use solid unvented disk brakes to keep weight down (for different reasons). 3, 10in rotors do a great job of stopping an aircraft that weighs 10,000lbs from 120mph on landing. As everyone has said your brake size will not be an issue as you wont even be able to have long hard and sustained brake applications like on pavement, so why not shed the unnecessary baggage (youll always be able to slap on bigger brakes for auto X later).

Hauling a cage around will also slow you down a bunch, give you unneeded momentum. Try to convince your wife that rally cross is much safer than riding a motorcicle in traffic and even if you flip the pillars wont crush, from my knowledge cages help more for impacts not roll overs. invest the $$ into a diff or something that can help you control that 200hp in the sand.

Also, on a side note, don't take this the wrong way, but I bet if you listen to the chaps on here and come back from your first few events placing in the top half of your category you'd be a much happier lad than having spent a LOT of $$$ and placing in the slow half.

Valentin;

I am going to be installing a 3J lsd in the transmission. Been working with their U.S. importer for over a month to try to decide the correct ramp angles for this application. Either 45 or 90. Been a struggle as he cannot compare our sugar sand to any other surface he has done a diff for.

As far as the cage, my wife is an Italian woman from New Jersey. I don't convince her of anything. I just listen.

Quote
DanielSL
Valentin;

I am going to be installing a 3J lsd in the transmission. Been working with their U.S. importer for over a month to try to decide the correct ramp angles for this application. Either 45 or 90. Been a struggle as he cannot compare our sugar sand to any other surface he has done a diff for.

.

Might want to get a new technical adviser if they are deciding between a 45degree and a 90degree ramp angle for accell lockup.

---

____________________________________________________________-

One. Class -- 2WD

www.quantumrallysport.com

http://www.facebook.com/home.php?#/pages/Quantum-Rally-Sport/281129179600?ref=nf

The issue is the gentleman that runs 3J USA has never seen sugar sand. So he has no reference to it. I am actually going to ship him a coffee can full of the stuff, so he can get an idea of what I will be trying to hook up in. Luckily, all of our events are at the same site this year and next year.
The 3J lsd comes with 2 different ramp set ups, that you can switch between. So he will be setting it up for what we feel is best, and then a secondary "best-guess" option. So if the first one is not what I expect, I can swap to the other ramp set before the next event, and try again on the same surface.

Simplify, then add lightness.

---

"Talk about drugs. Driving a car like that, going that fast, it’s like all the drugs at once." - Tommy Byrne

"Now, Pinky, if by any chance you are captured during this mission, remember you are Gunther Heindriksen from Appenzell. You moved to Grindelwald to drive the cog train to Murren. Can you repeat that?" - The Brain

Got the rear shocks and springs installed. I was actually surprised that the car did not sit higher, considering there is no cage installed yet. It actually sits higher than stock, but lower than it did with the VR6 wagon springs installed.

I went with the 250-25Kg springs for now, as they were the softest set available for the Mk.4 GTI from HotBits. The 230-30Kg will be kept in reserve for after testing, and for any RallySprints.

For now, as I recieved no answers to my question about helper springs, they are mounted at the top. The way the adjustable collars are designed, they fit at the top against the car, instead of at the bottom on the lower control arm, so I oriented the helpers to the collars.

Even though HotBits informed me that the passenger side may need to be swiveled to avoid the filler neck, I cannot do so, as the reservoir would actually hit the spring. Also, I would need to cut into the control arm with the plasma cutter and notch it to allow for clearance.

For now, it just rubs the plastic protection piece, but doesn't interfere with the filler neck itself. As I may go to a full race fuel cell in the future anyways, I am not going to let it bother me.

Quote
DanielSL
Valentin;

I am going to be installing a 3J lsd in the transmission. Been working with their U.S. importer for over a month to try to decide the correct ramp angles for this application. Either 45 or 90. Been a struggle as he cannot compare our sugar sand to any other surface he has done a diff for.

As far as the cage, my wife is an Italian woman from New Jersey. I don't convince her of anything. I just listen.

You will never notice a difference.

---

Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

Pete;

With my wife... or the ramp angles?

I finished clearancing the front bumper cover, for the front mount intercooler. Added a heck of a lot of holes, to make sure airflow to the core was maximized, without ruining the structural strength of the cover itself.
The top row of three holes is where we will install the mounting tubes for the front light bar. Going to install three 1" tubes, which will be sleeved with receivers, and quick dis-connect pins.
I also installed some LED flood-lights. One of my vendors from work gave them to me as samples when he found out what I was building. As the Rallye 4000's I purchased are spot lights and pencil beams, the flood light version will complement my lighting options. 1100 lumens per light housing, with only a 0.5 amp draw.



Edited 1 time(s). Last edit at 10/30/2016 01:30PM by DanielSL.

Less angle = more hold, no? Sand is very loose grip sooo want more hold?

That big cooler of yours and the lights are quite low, not afraid of losing them?

Why such a massive cooler? You ought to experiment with smaller, more efficient coolers and measuring intake air temps on yer dyno/street. The endtank design of yours is not very good, there won't be much airflow in the bottom half of the cooler anyway. Ideally shorter across and opposite entrance and exit with tapered cast ally end tanks. Like this:





Edited 2 time(s). Last edit at 10/30/2016 03:17PM by tin.

Light bar for the rallycross car?

Quote
alkun
Light bar for the rallycross car?

Looks cool, brah.

Valentin, the intercooler is from EuroJet. Proven on dyno to be one of the most efficient designs for the Mark 4 cars. I initially purchased it as part of the package simply because I got it from the shop for $150, for a kit that runs between 7-800 not including shipping. But over time, and looking at other FMIC kits as well, I also like it because the IC hoses are mounted up high on both sides. Less chance of tearing one off in an incident. A lot of VWAG FMIC kits have the IC hoses mounted down low, or one low, and one high. This is the safest for reliability and durability.

As far as the lights being low, I am not worried as they were freebies, and I can get them replaced for free whenever I want. I'm going to pick up a couple of more sets for the dually and the trailer for work lights. The Rallye 4000's are all going to be on the high bar, and that's the expensive stuff.

Do keep in mind that if its proven on the dyno doesn't mean it works on road. There are a lot of variables when you are actually driving. Take a look at some designs used in race applications, this Subaru for example:



Note how narrow the bars are and the high density of fins, this turbulates the charge air inside and promotes conduction of heat to the intercooler. Also the shape of the end tanks does a lot to distribute flow evenly through the cooler.

Note this F1 cooler (particularly the dimensions and where the endtanks are situated):


The Eurojet intercooler looks like it would be effective at very high speeds only, because of the low density bar and plate core it would need a lot of wind to cool. This type of core flows well, but cools poorly. Also it's waaaaay too big for 250hp and give you ample boost lag. The size is for a massive turbo and something like 400hp.

Give baffles a serious thought as well. Air always takes the path of least resistance and if there is a way it can flow around the intercooler it will do it and render the thing useless.