180hp 1.8t in Bug

[volkdent]

The day was spent at 034 Motorsport. Mike did a bang up job getting the plumbing done for the turbo. I got the intercooler mounted where I think it will work out really well. You can see I cut out the space behind the IC where the hot air will exit through the stock grill. Cutting those out also gives me access to that compartment to get the LEDs installed for my 3rd brake light. There is more lag now as the path is longer and the volume larger, but the power just keeps coming. On one end the alumunim is hot, and on the outlet side it's totally cold! When the GT28RS is installed, it will be a necessity, so I might as well get used to a little more lag now.









Jason

[evilC]

Hi Jason,

A very impressive installation!

One query - Will the intercooler actually vent through the rear grilles under the rear window? I thought this was a high pressure area that under normal circumstances is the cold air inlet for the carb(s). I assume that you will be taking the cold air feed to the intercooler from the side windows? If that is so the air pressure/air flow is not too good and may not overcome the high pressure under the rear window.

Clive

[Panelfantastic]

I do hope you plan to beat on this thing for a while before any major renovations ... I wanna hear about some street exploits .

Jeff-

[kuleinc]

So when willyou be offering a whole conversion swap kit? That is so wicked... I was looking to do the same thing, but with a TDi motor, but money, little to no fab skills, and school put an end to that right quick.

[volkdent]

Originally Posted by Panelfantastic

I do hope you plan to beat on this thing for a while before any major renovations ... I wanna hear about some street exploits .

Jeff-

What are you talking about, all I DO is beat this thing!!! How do you think I break stuff?!!!!

Jason

[evilC]

Hi Jason,

I'm not at all sure about the high/low pressure areas but this was my logic:
The rear vents are the only visible inlet for cold air to the normal single carb? The flutings behind the grille imply (to me)an airflow into the engine bay whilst protecting from rain penetration. I would expect the shape of the beetle body to create a laminar airflow over the rear window. This was I understand Dr Porsche's original intent to create a tear drop shape. If he had required a solid negative pressure area behind the rear window then he would have created a kamm tail. In general all the aerodynamic aids I have seen for beetles do take advantage of the laminar flow by placing wings etc hung out of the back including integral intercoolers. If there was a low pressure area at the base of the rear window then I would have expected a roof lip spoiler above the window to enhance it.

With regard to the side scoops, I agree that they are in the logical location but I would have expected the airflow to be reasonably turbulent not least because of the flow from the edge of the front screen. The shortness of the beetle body would, I would have thought, prevented the airflow becoming laminar again to create a positive pressure. The half moon vents in the rear quarters of a beetle body are to demist the rear screen, in other cars they are extract vents. If they are inlet vents (as would be supposed with +ve pressure at that point) then where is the air extracted from within the car?
I have no proof that any of those thoughts of mine are correct and I would be pleased for someone to correct me.

Clive

PS If my suppositions are correct then the air will flow through your intercooler but in the opposite direction???!!!

[volkdent]

Well I'm glad you are as unclear as I am, it's the bug shape that puts a real clink in the deal. If it had a flat roof or this or that, it might be more predictable, but you are absolutely right, it might flow backwards!!! I'll have to run some tests and I'll post my results!!!

Jason

[kuleinc]

I'm very interested in how this goes. Those vents behind the rear windows on the side are quite a mystery, I would love to know definitively if they flow in or out.

[volkdent]

Originally Posted by evilC

Hi Jason,

A very impressive installation!

One query - Will the intercooler actually vent through the rear grilles under the rear window? I thought this was a high pressure area that under normal circumstances is the cold air inlet for the carb(s). I assume that you will be taking the cold air feed to the intercooler from the side windows? If that is so the air pressure/air flow is not too good and may not overcome the high pressure under the rear window.

Clive

Clive, I'm glad you brought that up. How sure are you that that idea is true? If you're 100% I'm gunna have to change my thinking, I used to think the same thing. But the more I understand about aerodynamics, the less I think this is likely.

When I was down at 034 I explained my idea of the ducting, strictly the pathway, not mentioning high and low pressure areas. The tech who worked on my car, Mike, mentioned he thought NACA ducts in the side windows ducting into a plenum then out the vents would work great, said NACA ducts flow serious air. Then Javad, the owner, said he thought scoops would be a better bet, really trap air and force it through. Finally, Christian (Miller, KONI Challenge Series points leader) said he thought scoops and make sure that the exit duct to the rear vents was very well sealed, as he figured the vacuum created in that location was actually going to be pulling more air through the intercooler than the pressure from the scoops.

All of these guys are SERIOUSLY into motorsports, Javad has been racing and setting up racing cars for years, and Christian is a professional racecar driver with a lot of R&D experience. ALL of them had the same idea as I did regarding high and low pressure areas and airflow in general. We could all be totally wrong, so I'm going to have to do some R&D of my own, build the setup in cardboard then put little red yarn pieces on the ducts and see which way they blow.

When I think about the stock idea of those ducts, I actually think they may be there precisely to pull the hot air out of the engine comparment! Regarding the NACA ducts, I spoke with a drag racer at Bugorama a few years ago, and he had actually tested the pressure from the duct placement in the quarter windows, and he said he was seeing 5psi!!! I don't know, I hope the old idea isn't true, but if it is I certainly stand corrected. My little test should let me know if it'll work or not.

Jason