Big, bigger, biggest......turbo!

[audiman]

Mihnea using Tom's PC:

Dunno Dan, we'll have to see if I ever get my hands on an ECU from one of those... so far I've only been working on the upcoming Porker 997 turbo so far and that's already fun to map with 2 VNT turbos on a flat 6 engine...

It will come out some time next year and it'll have 480 PS by the way, yeah I know, not quite as impressive as the $1M Bugatti....

Mihnea

1000hp -hey, VAG have done it with the Bugatti Veryon - 16 cylinders and 4 turbos, 1 turbo for each bank of 4 cylinders. Easy!

Wonder what Mihnea could do with that engine?!

[Billman]

Should there come also VNT turbo for the 5cyl turbo???

[flossymeister]

I agree with BRY and Andy_Casey......

go for a supercharger and turbo combo. worked a treat for lancia and i seem to remember reading one of the main car manufacturers is bringing back the idea again on a forthcoming model...... !

[audiman]

Yeah the the new Polo Gti IIRC is gonna have super and turbochargers

[whakiewes]

Twincharging is very hard, and very expensive to tune. Its not near as easy as bolting on a supercharger and bolting on a turbo. They have to be matched, as in what time each will suffice to the other. There has to be a bypass on the supercharger to inable the turbo to induce air properly, otherwise your going to use all of your turbo energy to push the rotors in a supercharger. You have to have massive amounts of plumbing to do it right, and there is only so much you can go before stuff starts to break. MOST superchargers can't spin at the rate in which a turbo will flow air through it, so like I said you have to build an intake manifold, that then attaches to the supercharger, but also have an inlet for the turbo. You really need individual throttles to make this work, and a huge pocket book.

This doesn't include tuning. VW has an engine now that is twincharged, available in europe, but it only have about 180hp. Lancia was able to do it because they had the best software and mechanical engineers at their disposal to tune the cars. Have you ever tried tuning a car for turbo? Now add in the factors of you have one that is pushing a cooler air than another! Add in the when the turbo flows air through the supercharger, it heats up, but to what degree should you accomodate this? Where does the air go from the turbo whenever you close down the throttle...it has to flow out of the supercharger before hitting the bypass, so now your stuck ruining the blower. What about accomodating in your tuning for when the turbo pressure exceeds the supercharger pressure? What about close-loop tuning for street driving, not WOT? What happens when your at say 1500 rpms, you want to pass someone, and you do it at partial throttle? Tuning for that would be 'bloody' hell.

Its possible, very possible, but the means and time it would take make it not worth it. Your best bet as stated before is make an engine that rev's. Generally anyone will tell you 10k is the limit on a street engine, more less for the fact that your idle will be non-present, your powerband will be super long and less efficient(depending on what your doing), and more. It wouldn't take much to build a 3B to 10k rpms. Your going to need lighter than 600gram rods, and or shorten your rods to lower the weight, but lengthen the pistons to keep your rod/stroke the same. There is tons of engineering that would need to be done, but its possible. You have a ton of room to bore the 5-cyl., so why does everyone stay at 81-82mm? It appears to me you have a good 2-4mm between each cylinder, so use that. Try to get the bore/stroke as square as possible, or squarer. The head won't need much work, other than Ti retainers, valve springs, lifters, and some serious porting to match this. Your lifters may even be able to handle it, not sure what the limit is on the 3B. Put in your MLS headgasket, some crazy like 284 cams, tune the hell out of it, and enjoy your ride. The crank on the 5 isn't very long, so I can see this being very feasible. Even at 9,000 rpms, you could have a turbo that reached full spool at 5000, and be well into your power band between each shift.

Another thing to consider is that there are companies that take the Garrett Turbos, and improve on them. Take Precision turbo's with a PT61, T61 housing which in general flows better than the T04E housing of the GT35R, add the ball bearings, and your set. Most of their claims are usually pretty conservative too. Sound Performance does this as well, making the SP61, SP63, SP71 etc...The big HP Supra's are all running these variants. They even have a 100mm turbo. Thats for the 2000hp guys though. I would bet if you were at 700hp, and you wanted more, you could play around with turbos and be at 750 at the same boost pretty easy. Give up 200rpms of threshold, and be set. Another thing to consider is taking a look at the engine. Pull of the head, bring it to a professional shop, let them port it and flow bench it to hell, and get it so its to its best. Then do a 3-angle if you want torque, or a 5-angle if your shooting for supreme power, flow bench it some more and see where you are. Still not good enough, get custom oversized (1-1.5mm) valves with narrow stems, single locking keepers, and flat faces to optimise your combustion. Now see where you are. Just off my head on a BMW engine, doing a 5-angle, street porting, and intake polishing...as well as port matching the exhaust and intake manifolds, we got a 42% increase in flow. By doing a 1mm oversizing of the valves, without taking into effect the narrower stems, lighter mass, slope of the valve fact, etc...it would have a 3% gain, PER valve. Change the silicon content in your piston so that it doesn't expand/contract as much, get much tighter tolerances with your pistons and rings, less blowby = more power. Knife edge your crank, take off 10lbs of rotating mass. General rule of thumb in engine building is 1lb=1hp...so take off 10lbs, that 10hp. Now add in titanium rods, of course were talking about a budgetless engine. Take the mass from 600grams(the lightest aftermarket rod I can find for the 5-cyl), down to 325grams. Thats 275g per rod that you lost, or 1375g overall. Thats very substantial! Your pistons will be less mass because we will shorter then skirt, change the silicon, dish the face slightly differently, leave your C/R at 9.3:1, and be done.

So you want 800-900hp...there you go my friends. Thats what it is going to take! I bet it could be done without, but thats what I would do.

Wes

[whakiewes]

Another thing about the GTI twincharged engine is that its not built for supreme power. It has an ittybitty turbo, that isn't meant for power. The theory is that the supercharger produces boost off the line, so that gives you your get up and go power, but superchargers aren't efficient on the highway, i.e. cruising at 70mph, so they use the turbo which is VERY efficient on the highway, bypass the supercharger, so when you want to advance at partial throttle, the turbo spools producing power without the blower. Totally different setup than one you would use for raw power. They are trying to come up with an efficient alternative to diesels.

[flossymeister]

hey, I never said it'd be easy !!

buy a bigger engine and a whole new car to put it in might be another option

Fantastic description of what to do to the engine, though!

Tim

[Erikb]

impressive write up Wes, interesting stuff!

[Audi500HP]

I would like to have a 600 hp S2, reabable, but take the adventure of 700 or 800 hp it going to cost enought to buy a nice 911 3.6 turbo, and start another project

NO replacement for Displacement.......... I like REVS engines, but usually it took a lot of money to build it....

A question: how much stress can support our 01E gearbox?........ this is the next reason to take in concience in this adventures......... Gearboxes.......... I hate to rebuild a gearbox.

Any aprox of the cost of a new racing gearbox? and where to buy it?

Thanks guys.

[corrado]

Hey guys i though I would post this dyno


Its from a vtec Honda 1.8 engine, its running a Gt42 ball bearing turbo. Now to answer his quest about the turbo for 600+hp I would go with this turbo on the 3B platform.

Big turbo is the only way to roll

[Sweeper]

Do you actually need a bigger westegate for Garret GT30R , 35 , 40 , 42 ?

[whakiewes]

I haven't ever looked at an S2 wastegate, only a 951 wastegate. It always impressed me that older Porsches and Audi's ran external wastegates from the factory. Typically on our BMW's (if you can't tell, I was huge into BMW's, M3's etc....just bought a CQ in the States and plan to get some power), but wastegate is typically decided by two different factors...exhaust flow and PSI. PSI being the less needed variable. A 3.0L BMW 6-cylinder, rev's to 7000 rpms, mine 7500rpms flows a lot of exhaust. Much more than say a 1.8L Honda VTec, even at 9000 rpms. In turn, we would run an HKS racing 50mm wastegate, and of course alter the spring in the wastegate to our minimum boost. On a previous 951, we ran a Tial 38mm, as the 951 didn't have that terribly much exhaust power due to the lengthy manifold setup, and the 38mm was more than enough to pump out the exhaust. From what I have seen, I would run the Tial 40mm on the 2.2/3L engine, as it has a bit of exhaust, but not all that much. The 40mm has springs all the way up to 28psi. For the guys running over 28psi, you have to switch to a larger wastegate to accomodate a bigger spring. This will in turn effect your boost threshold.

Another general rule of thumb is to run the smallest wastegate possible for your application. The smaller the wastegate, the faster exhaust is directed towareds your turbo, and faster it will spool. If you have an electronic boost controller, you can again adjust it more by altering the vaccum pressure to open the wastegate.

Really weird thought, but I have found that using a smaller wastegate, I can usually see my turbo spool anywhere from 2-1000rpms sooner.

I am definantly open to suggestions here, as all you guys have proven what works and doesn't work on the 5-cyl, and I am about to start working with it, so I would love to hear all of your ideas/experiences.

Wes

[flossymeister]

the power curve of that honda would give you a nose bleed !!

and i thought RS2s had a spot of lag!

[dan_b]

That Honda's going to be having a hard time keeping all that torque on the straight and narrow surely? Bonkers!

[corrado]

I have used 38 and 44mm in a 16vT vw and have not found any major differences in boost build up, nothign was changed except the w gate. Boost at the time was around 24psi.

For anything over 500hp I would go with a bigger than 38mm wastegate. I have had great results with tial brand.
Another way is to do twin wastegate setup, although this would be overkill for most street cars.

That Honda dyno is a street/drag car, the power comes at late rpm meaning that you are aready moving lowering the chances of wheelspin. But of course that thing was meant to be using slicks.