homemade turbo

[6Speed]

My buddy has a stock turbo from his eclipse that I can probably get for next to nothing. He can also help me get an intercooler (have no idea where I'd mount the intercooler). Anyway, my parent's house has a lift in the basement, and I have access to a welder and plasma cutter. I can weld decently, but I have a friend who welds for a living, and I'm sure he would help me. I think I'm going to buy the turbo header from cbperformance.com, and see if I can fab up the rest of the ductwork myself. I think I can build it for a lot cheaper than the 3000 dollars that the hideaway kit costs. One thing I'm curious about though -- I know how fuel injected turbo cars add fuel with boost, but how does a carburated car add fuel per boost?

Has anyone else attempted this?

[boygenius]

A carbureted car increases fuel levels with the use of a boost sensitive fuel pressure regulator. The pressure regulator keeps the fuel pressure a few psi ahead of the boost pressure. For more indepth information on making a turbo kit get the book "turbomania." It covers everything from turbo selection to carburetor modification. I wish I could be more helpfull but my friend borrowed my turbomania book and I haven't seen it since. Hope that helped.

[vennard]

also get a copy of maximum boost by corky bell (i think) not vw specific but very helpfull. Take a look on shoptalkforums.com They have loads on turbo installs.

Karl

[Ian66]

My car is currently turbocharged and uses a CB performance turbo header as well. I don't know anything about an eclipse turbo charger, but if the engine capacity is the same size as your vw engine it should be a reasonably close match. In my opinion I think turbo's should be a little undersized in comparison to normal turbo cars, because you don't realy want to run too much boost, but would like it to be very responsive down low. Having driven a WRX recently, where the boost comes on very low in the RPM band makes the engine run like its actually 4 litres instead of 2 liters in capacity.

My original setup was based on webber 44 idf's in blow thru configuration. This worked very well, but consumed fuel like no tomorrow. Performance wise, with 12lb of boost the car would beat a standard wrx by two car lengths at the end of 400 meters. Great fun! but sealing the carbs was dam near impossible. You have to get shaft seals made up, and their not very effective anyway. As one of the other guys suggested, you must use a rising rate fuel pressure regulator, which maintains the fuel pressure 3lb above the intake manifold pressure(whether under boost or not). Additional enrichment with carbs is done by using a system called modulator rings. at low engine speeds/boost they have no effect, but under boost the ring(restrictor at the top of the carb) creats a greater pressure drop from the top to the bottom of the carb, resulting in additional enrichment.

For best results you should use a webber DRLA carb, which is designed for blow thru. If you decide to use blow thru carbs, you should consider buying a MSD 6BTM, which can retard timing as boost comes on, otherwise you will risk pinging while under boost, or you will have to drive the car with the ignition set way too much on the retarded side, making the car very hard to drive.

I've since upgraded to EFI, using a Wolf 3D laptop programmable ECU with MSD 6A ignition. IT works very well, but is MUCH harder to get the tune right in comparison to the carbs, where I had only three jets to worry about. Drivability is awesome though, because the ignition and fuel maps are fully controllable. I can change into 4th gear at 35km/h (1300 RPM) and the car doesn't stall or splutter. It actually has torque at that engine speed which is pretty impressive for an engine running a 296 degree, .530" lift cam.

Consider this most of all. There is no such thing as a CHEAP turbo system. If you do it cheaply, it either won't work properly or will result in you blowing up other engine components. Believe me I've learnt the hard way.

Have a look at my website at http://vwturbo66.port5.com, it may give you some idea's. Maybe you can avoid some of the costly mistakes I've made...

Cheers,

Ian Swinkels.