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Hi there I have fitted the vnt mechanism to my turbo now, and its interesting. It spools up faster, but i also gets rid of the popping on overrun and quietens down the exhaust note under lower load. I'm not sure if i like this J
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Last Edit: Jul 7, 2005 20:44:56 GMT by Blown_Imp
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booo hiss, it has too sound like a demnted harpy its the law ;D drill a little hole in the down pipe , thatll get it back
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"quote hairnet"
I'm not paying nine pound for a pi$$!
[/quote]
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There is a little holecoming in the shape of a 35mm external wastegate. i think i can restric how much the vanes close, and therefore still make the righ sound. Question is do i want it to come on boost like a banshee, or make boost quicker and lower RPM?
J
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depends if u have to drive it to work and back every day, if not, all in one big fiery lump ;D ;D
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"quote hairnet"
I'm not paying nine pound for a pi$$!
[/quote]
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racer86
Posted a lot
'72 BMW 2002 / '72 Alpine A110 Gordini
Posts: 2,184
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hows it going have you had it boosting now? whats it go like? i don't think id worry about it being quiet!
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Its going good, its smooth and pushed hard. I have however found out that my cylinder head/block combination is 10.5:1 comp ratio :-( I have seen 3psi and I'm getting ready for more. Been told aout a chap that hires out wideband O2 meters, looking at hiring that so i can do a bit of self tuning. Also learnt about plug cuts so i will have a go at that too.
Its an everyday car but i don't mind noise, I think ill keep it on there but restric its operation so i get all the aural benifits!
Cheers J
P.S. how do i put up a wee pic like you guys next to your name?
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How are you controlling the VNT Vanes ? It wont last for long on a Gasoline engine, the EGT is too high. All Variable geometry turbos currently on the market are running on Diesels, as they have much lower EG Temps. It makes a broader spread of power because of quicker spool up. Do you know what it was from originally ? We have got shed loads of them in the skip at work ;D But not really any good on Gas engines don't run more than 5-6 psi without lowering the Compression ratio. Are you running an Intercooler ? or is it straight through ? You could run it richer to keep the temps down as well. HTH Dom
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The VNT turbo has been run on a petrol engine, a 2.2 dodge engine from the 80's used one. It should work just finr for now, if the mechanism does give me jip then i can fix it out an it also mean i can choose the effective AR ratio of the housing. I cannot use the mechanism to comtrol the boost pressure as the golf that it came from uses a vacuum pump and the ecu to control the actuator.
I have a very effetive intercooler, that should be able to keep it all under control.
I can run higher boost that that if i go to a full igniton management system and wills rings. All of the WRC cars today use high boost high compression. The subaru last year was running between 12 and 13:1 depending on the rally, and 4bar absolute boost pressure (thats 45psi)
I'm not looking for mega power its all just a bit of fun!
J
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How are you controlling the VNT Vanes ? Thats an important question, i have not seen any successful DIY attempts to operate a VNT mechanism, its quite complex. You want the vanes to be nearly closed at low boost, to aid spooling up, but for them to open up at higher boost pressure/engine speed to prevent overspeed of the turbo. Effectively you want them to be as closed as possible all the time, but without causing overspeed. The outright performance of a VNT is much the same as a wastegate job, the beneit is that the VNT will make more efficient use of the gas flow at lower speeds and boosts => spools up more easily. The Actuator is not connected to the inlet like in a wastegate application, its connected to a vacuum solenoid, and I do not know what calculations are done to enable the solenoid to decide where it should be. It wont last for long on a Gasoline engine, the EGT is too high. This is true, though I suspect the distictly 'non-lean-burn' charateristics of a hillman imp on standard compression ratio with a carb will keep the temepratures low enough for the blowa to survive. That said if you do a load of track days all at once or start towing heavy trailers you might pop it! It should be OK up to a gas temp of about 750°.
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1972 Fiat 130 1985 Talbot Alpine 1974 Lancia Beta Saloon 1975 + 1986 Mazda 929 Koop + Wagon 1982 Fiat Argenta 2.0 iniezione elettronica 1977 Toyota Carina TA14 BEST CAR EVER!!!!!!!! 1979 Datsun B310 Sunny 4-dr 1984 Audi 200 Quattro Turbo 1983 Honda Accord 1.6 DX GONE1989 Alfa 75 2.0 TS Mr T says: TREAT YO MOTHER RIGHT!
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The really useful thing about the VNT mech is that i can effectivly vary the AR of the housing, fix it where i like (boost threshold, and peak restriction) and modify as needed. I have a 35mm external wastegate to control the boost as i don't have any clever electronic devices (its a 1960's car!)
J
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Have you connected up the vacuum actuator on the blowa? if so, how?
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1972 Fiat 130 1985 Talbot Alpine 1974 Lancia Beta Saloon 1975 + 1986 Mazda 929 Koop + Wagon 1982 Fiat Argenta 2.0 iniezione elettronica 1977 Toyota Carina TA14 BEST CAR EVER!!!!!!!! 1979 Datsun B310 Sunny 4-dr 1984 Audi 200 Quattro Turbo 1983 Honda Accord 1.6 DX GONE1989 Alfa 75 2.0 TS Mr T says: TREAT YO MOTHER RIGHT!
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Ive used the vaccum that normally goes to the distributor. The actuator is very sensitive and is constantly moving.
J
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Hmm. I don't actually know if that will give a good 'strategy' or not! Are you gonna try locking the VNT in differing positions and varying the boost with your external WG?
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1972 Fiat 130 1985 Talbot Alpine 1974 Lancia Beta Saloon 1975 + 1986 Mazda 929 Koop + Wagon 1982 Fiat Argenta 2.0 iniezione elettronica 1977 Toyota Carina TA14 BEST CAR EVER!!!!!!!! 1979 Datsun B310 Sunny 4-dr 1984 Audi 200 Quattro Turbo 1983 Honda Accord 1.6 DX GONE1989 Alfa 75 2.0 TS Mr T says: TREAT YO MOTHER RIGHT!
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Yeah thats what i am doing at the moment, ive plumbed in the vacuum for now to see how well it works. Being able to move the vanes and vary the AR ratio is great for an unknown turbo engine as i can vary the boost threshold and spool up.
J
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Excellent work! Sounds mega interesting. Have you got a carb on there or some sort of fuel injection?
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1972 Fiat 130 1985 Talbot Alpine 1974 Lancia Beta Saloon 1975 + 1986 Mazda 929 Koop + Wagon 1982 Fiat Argenta 2.0 iniezione elettronica 1977 Toyota Carina TA14 BEST CAR EVER!!!!!!!! 1979 Datsun B310 Sunny 4-dr 1984 Audi 200 Quattro Turbo 1983 Honda Accord 1.6 DX GONE1989 Alfa 75 2.0 TS Mr T says: TREAT YO MOTHER RIGHT!
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Yeah its just carbed up with a maestro turbo carb, metty turbo high boost spring in the dash pot, and a metro turbo jet. Maestro intercooler, and a vnt-15 turbo all working so far. I have also fitted a microdynamics ignition controller, this is a boost controlled unit that intercepts my igniton signall and retards it accordingly.
cheers J
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