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

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DanielSL
Does anyone have a good idea on installing sunroof block off panels?

I know in stage rally, you cannot use fiberglass or carbon fiber; but luckily in RallyCross and RallySprints I can.

You may not in RallyCross. Sunroof structure must remain in place and roof components must be steel, unless otherwise done so by the OEM. (So fiberglass hardtop shells are legal and glass sunroofs are legal, if they are OEM)

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Pete Remner
Cleveland, Ohio

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

Great. Damn. Now I got a huge panel of pearl grey fiberglass buffed to 800 on one side, and 2500 on the other side. I've got a night race this weekend. I will check with our tech inspector, and our Regional event chair. If its not legal, I guess I can still cut it down, and use it for a template to make a metal one, lol.

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DanielSL
Sometimes its the little things... more whooosh!

That splitter valve shows just how un-serious you are. Yah, let a bunch of metered air escape and wonder why it doesn't run consistently. But I want it to sound cools!!

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One. Class -- 2WD

www.quantumrallysport.com

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

Josh, you would be correct if I had gone with a standard BOV. As the way the engine sits with a standard diverter, a DV+, or an aftermarket DV, the turbo is going into overboost, and overspinning the impeller as I am always at full throttle and never letting off the gas 80-90% of the time.

The splitter was gone with to let a little of the unneeded pressure get out, while keeping enough to keep the turbo spooled all the way up the 10-20% of the time I am modulating the throttle.

The dyno, Maestro readouts, and tuning results don't lie. They just give my mechanics the information they need to dial it in a little closer to better each time. We run dynos after every modification, tweak the Maestro tuning, and look over the computer results after every test, and every session. Heck, they didn't even Stage 1 tune the car, as I don't need the extra power. We want a more linear and flat torque curve than stock. And with tuning, the torque gets more spikey and less linear. So with the maestro, we can adjust in tiny little segments.

He has a point, though. If the stock diverter valve is causing a leak, then cap off the mounting holes and throw it away.

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Pete Remner
Cleveland, Ohio

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

The problem that was found was that it wasn't letting enough out, which was over-spooling the turbo. I am not in the mood to grenade a K04 at speed. I just finished paying off the engine and install.

I'll admit that I don't know anything about vw's. At the same time I'm pretty sure that that josh is right......and also that any overboost situation is related directly to the wastegate or control of the wastegate and not to the splitter or bov. Fixing an over boost condition with a splitter sounds very suspect to me. Are you experiencing boost creep, boost spikes, does you vw have turbo rpm capabilities that you are logging, or are you experiencing "surge" when the throttle plate is being closed? Your boost measurement occurs between the throttle plate and the pistons correct and not between the turbo and the throttle body?

Mark, from your detailed reply, I can tell you that you understand much more than I do. I will have to check most of those queries with the shop. I do know that we are logging the "overboost" signal, but we cannot actually see the turbine wheel rpm. So I know we do not know if it is over-spinning by 2,000 or 20,000 rpm's. There is surge after throttle closes, as well. But I do not know if in that engine, it is an actual throttle plate.

Yeah, I'm not going to touch that one at all. There is so much going on it is fractal wrongness - no matter if you look at the big picture or the slightest detail, it's wrong.

But at least you got a big noisemaker like the stancebros use, so there's that.

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Pete Remner
Cleveland, Ohio

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

Keep getting updates about this, couldn't help myself. This is from a textbook:

Diverter, recirc valve or BOV is for controlling compressor surge/stall when the throttle is closed while on boost.

Turnbine RPM is controlled via waste gate.

Overboost control is usually provided by a relief valve downstream the throttle.

Well, that seems to make sense. My car is a "drive by wire" system. So whenever I let off the throttle to modulate, the splitter valve will open while the turbo is still making boost. But when I am at throttle, the over-spinning of the impeller wheel would be controlled by the wastegate.

Overboost relief valves are found on planes as a safety feature not as a boost control strategy. Someone out there has surely used something on a car, maybe even appropriately, but if that thing you put in there was used as part of your boost control strategy (boost spikes or boost creep) I would stop using those guys. Maybe I'm wrong but it would seem they should be able to control a stock boost level using the stock components without many problems.

You still have a MAF system and haven't switched to speed density right? Your bleeding off metered/measured air and that usually isn't a wise thing. I don't think it matters as much when you are using speed density....

It is a 50/50 split when it comes to the old blow off valve war and everyone seems pretty bunkered in on their side. All I will say about it is that I have seen more evidence that boost response and everything associated with it gets better when you don't have a blow off valve. Isn't that a positive thing in racing? Granted you might not get 300,000 miles out of your journal bearing turbo. Also, the sound of a dying pigeon sounds way cooler than a little psssst......at least in my mind. hahaha

One last thing and this could actually be useful.....I would personally NEVER run or recommend someone else run a blow off valve that didn't have a filter on it. Under throttle manipulations you can create a vacuum at the exit of the BOV and suck in dirt/dust. On your street ricer you may never notice the difference but in a rally/rally cross situation you really are just asking for dirt in your pistons. But this also might muffle the noise so it is quite a pickle.....

So much facepalm on the tuner

Rule #1 for tuning:
If your hardware & software combination results in surge, figure out why and FIX it.

Helpful tuning tips:
Narrow down your search for surge issues.
---Pressure test entire intake tract to at least 5psi over your expected max boost pressure
---Test WGFV (N75 on VW) for proper functioning.
---Attend to known 1.8t common issues such as undersized plumbing to and from DV
---When all else fails, install a manual boost controller in parallel or in series with the N75 valve and adjust it to just below the tune's max boost command --- if this does not end your surge, then start diagnosis over because you missed something.
---Fire your tuner.

In the end, if you still have surge, the MBC bandaid is a far better solution that the swoooshy duck splitter bandaid.

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____________________________________________________________-

One. Class -- 2WD

www.quantumrallysport.com

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

Josh;

The engine has a brand new N75, and most of the piping has been changed when we started using the reinforced silicone Forge hoses. Also, with the large tubing of the FMIC, I would say we are more over-sized, than under-sized.

One of the sponsors suggested I get this:

http://www.usrallyteam.com/index.php?main_page=product_info&cPath=112_303&products_id=2017

I've been thinking of it. I just don't know if its a waste of money for a RallyCross car or not. Obviously I don't want to damage an interference motor, so anything that protects the engine makes sense to me. But since we already have the full Maestro suite, I think tuning makes more sense.

There is no blame to the tuner or the shop. We have only base lined the car, and run one test and tune. There's a lot of data to play with, and a heck of a lot more running and tuning before anyone can say they don't know what to do. Can't figure out everything based off of one test and tune and a couple of logs.

I really need to schedule and pay for like 3-4 hours of dyno time solid, and sit on the dyno with the computer and the tuner. Problem is my tuners shop is 45 minutes away from where the closest chassis dyno is at. So I'm paying for both shops time.

Band-aid for now. Surgery later...

Quote
DanielSL
Josh;

The engine has a brand new N75, and most of the piping has been changed when we started using the reinforced silicone Forge hoses. Also, with the large tubing of the FMIC, I would say we are more over-sized, than under-sized.

One of the sponsors suggested I get this:

http://www.usrallyteam.com/index.php?main_page=product_info&cPath=112_303&products_id=2017

I've been thinking of it. I just don't know if its a waste of money for a RallyCross car or not. Obviously I don't want to damage an interference motor, so anything that protects the engine makes sense to me. But since we already have the full Maestro suite, I think tuning makes more sense.

There is no blame to the tuner or the shop. We have only base lined the car, and run one test and tune. There's a lot of data to play with, and a heck of a lot more running and tuning before anyone can say they don't know what to do. Can't figure out everything based off of one test and tune and a couple of logs.

I really need to schedule and pay for like 3-4 hours of dyno time solid, and sit on the dyno with the computer and the tuner. Problem is my tuners shop is 45 minutes away from where the closest chassis dyno is at. So I'm paying for both shops time.

Band-aid for now. Surgery later...

Yeah your tuner is the problem, put it back to stock tuning and go somewhere else, basic stuff, no need for a dyno.

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Power means nothing if you cannot control it!