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Turbo a 1.5l ... 79' Rabbit by Brystephor on 06 Feb, 2016 22:33
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Hey guys! Brand new to forums for this specific thread! Now I'm seeing a lot of 1.6l n/a becoming turbo diesels, but I am buying a 1.5l diesel 1979 rabbit tomorrow. Its a 4 speed, odometer reads 50k, I am not sure if it works however so who knows truly. The engine does run and start though which is great! Especially for under $600 with a clean title...
Anyways. I am looking to turbo this motor. I would like some help as what to do with it. Here are my basic thoughts, plans, and wants.
Car as is: 1.5l n/a diesel. 4 speed. less then 60 hp.
Wants: No specific horsepower number, this won't ever be fast. This is a project car for me to learn on as I go, They're very simple cars which is why I am using one of the older rabbits, I didn't have a preference of diesel over gas, this is just a good deal so I am taking it.
-Turbo (obviously) Probably a VNT-15 from the early 2000's TDi's.
-Boost: about 15-20psi would be nice, but since its a project and not a daily (this will be a weekend warrior), 25-30psi wouldnt hurt (Understood I need a bigger turbo then the vnt 15, any suggestions would be good, I dont mind some turbo lag, I love it when the turbo spools and it just hits you.)
-Different intake and exhaust manifold. (I heard the ones from the 1.9l TDi's work, is this true?)
-Bigger exhaust? (When is this needed)
-Intercooler? Any suggestions would be good. Im curious if the 1.9l TDi's work and would fit.
-I heard the injectors were plenty big enough, someone to confirm this?
Big question: What do i need to do to the valves and head in order for this to be good? Will I need racewear/arp head studs? Metal head gasket? Will i need to doublestack headgaskets to lower compression ratio or would a single thick headgasket work or is the stock compression ratio fine? Valves? No idea about valves. All insight on that would be greatly appreciated.
Thank you guys a ton for the support and help! I wish it was a 1.6l so i could go off all the information that has already been posted and questioned and tested but it seems that the 1.5 is uncommon. And I am not sure how interchangeable the 1.5/6 are, once more, thanks and ALL opinions are appreciated. -
#1 by vanbcguy on 06 Feb, 2016 22:48
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The 1.5 block is pretty weak. It isn't a good choice for adding a turbo though you certainly could make it last a while if you are gentle to it.
You absolutely do NOT want to mess with thicker head gaskets. This isn't a gasser, preignition isn't a concern. If you have the head off you measure piston protrusion and then use the correct gasket.
You'd be much better off finding a complete 1.6TD and swapping it in, it's a direct bolt in. A later 80s 1.6 will have a more robust block, a proper turbo head (the prechambers are a different size), a proper turbo injection pump (with an LDA) and oil squirters for piston cooling.
Stock injectors on the IDI engines are plenty huge yep, nothing to worry about there.
1.9 intake manifolds have different shaped ports though they physically will bolt up. Exhaust manifolds are the same.
Bigger exhaust should be done at the same time as the turbo - you'll need to make a new downpipe anyhow, might as well do the whole thing. 2.5" is perfect for virtually any power level.
VNT 15 isn't a good choice unless you're handy with electronics or you want to build a somewhat complicated linkage to control the turbo. It is driven by the ECU on a TDI.
Sent from my XT1097 using Tapatalk
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#2 by Brystephor on 07 Feb, 2016 00:51
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No electronics. No wiring. Screw that vnt 15 then. Would a ko3 or t3 work then?
And when you say 1.6TD to be swapped in do you mean a 1.6d that had an aftermarket turbo or a 1.6d that came from the factory with a turbo? -
#3 by ORCoaster on 07 Feb, 2016 17:29
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The very best spend of your hard earned cash is to remove that weenie 1.5 and replace it with a block designed to do what you are thinking. If you can't afford a different engine there are some upgrades that might carry over to a 1.6 turbo in the future. Like the larger exhaust. And 1.9 intake. Make it breathe with ease and if you are not looking for mileage turn in the fuel delivery screw and see how you like it. Before you go dumping dollars though best take a few parts off and see what that 600 bucks really bought ya.
Start with the rear drums and axles. Then move to the front and check on those. Better to have it capable of stopping before you try to speed it up.
You have likely spent coin on the car, some fuel and perhaps an air freshener. But the one thing you are seriously going to need is a Bentley manual for this rig. This forum is great for all kinds of things but we do not retype the Bentley here. We tell you to get one, you make find one at the library, I did but there is no replacement for it so get looking. 35 bucks online unless it is used and I have seen them go for as low as 10 by some.
Good to have new folks saving the great little car of all times. Becoming a diesel head isn't all bad, it does have its upside. Let me think on what that might be.
Welcome! -
#4 by fatmobile on 07 Feb, 2016 19:49
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The 1.5 needs a turbo. A hill and a headwind will slow it right down.
Do it. I loved my 1.5 vnt-15. Engine is still going strong in my friend's car, without the turbo.
The reliable mechanical controller is pretty easy to build.
You do "need" headstuds.
The VNTs are cheap; under $250. That's including the exhaust manifold.
They are easy to rebuild.
They hang down so you can use a gasser intake instead of the restrictive (and sometimes hard to find and expensive) stock TD intake.
Gasser intakes are plentiful. Basically a free intake and exhaust manifold compared to the stock setup.
The exhaust is easier to build than stock because it easily clears the shifter.
They have a great sound. You can sit at a light and slowly rev higher,.. before your RPMs get too high the whine increases like it's going to blast off ziiinnnnnnngggggg. beyond hearing range then a second harmonic comes in and between the gears a big ol' BEWHUU.
They don't boost much above 18 but they are so fun at the low end.
Worst drawback in my opinion: It might be part of what is causing lower oil pressure than I would like. The 2 stock bearing surfaces are trimmed down to only about 3/16" of contact. New bearings have a little wider bearing surface. The bearing sits loosely into the housing, I don't think this helps with oil pressure, as oil can go around it.
I don't think the brass expands more under heat and seals around the bearing. Anyone know more about expansion rates of brass vs cast iron? Small, under 9/16" cylinder shaped bearing.
Pretty simple piece. I'm going to try to build/machine a better/tighter bearing. Inspired by a balanced turbo, new compressor wheel with too much clearance, need to ream a bearing to match the shaft if I want to save it.
Many people set them up wrong and give up.
Max turbo at idle and drop it off to almost nothing when floored.
I should also point out that the TD LDA is meant to reduce smoke when boost is off. Because the stock turbo doesn't boost until 2000 RPM, it gives you back pressure and no boost until then.
The VNT boosts right away so you don't need a TD pump. You can use a cheaper NA one. -
#5 by Brystephor on 07 Feb, 2016 23:32
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The very best spend of your hard earned cash is to remove that weenie 1.5 and replace it with a block designed to do what you are thinking. If you can't afford a different engine there are some upgrades that might carry over to a 1.6 turbo in the future. Like the larger exhaust. And 1.9 intake. Make it breathe with ease and if you are not looking for mileage turn in the fuel delivery screw and see how you like it. Before you go dumping dollars though best take a few parts off and see what that 600 bucks really bought ya.
Start with the rear drums and axles. Then move to the front and check on those. Better to have it capable of stopping before you try to speed it up.
You have likely spent coin on the car, some fuel and perhaps an air freshener. But the one thing you are seriously going to need is a Bentley manual for this rig. This forum is great for all kinds of things but we do not retype the Bentley here. We tell you to get one, you make find one at the library, I did but there is no replacement for it so get looking. 35 bucks online unless it is used and I have seen them go for as low as 10 by some.
Good to have new folks saving the great little car of all times. Becoming a diesel head isn't all bad, it does have its upside. Let me think on what that might be.
Welcome!
I plan on buying a bentley manual first thing! I see them from amazon for only $30. And while I will have about $1000 left over after buying the car (if the guy doesnt stop prolonging the sale) I am only looking to spend $300 to $500 on the car right now. My first priority would be the brakes, I can't comfortable go anywhere knowing that I can't reliably stop. Just figuring brakes out I imagine will take me a week or so as I am brand new to all of this. I like the idea of buying parts that can carry over to do a different engine if need be in the future! Will i have to custom make an exhaust or is it available to be bought? I don't have a welder, and even if i did, have only ever welded anything for about 30 seconds of my life. Gas mileage does not concern me. This is not a daily driver and even if it was I only get 18 mpg highyway right now, this car is a project that is meant to be enthusiastically driven when it runs (Yes i know it's slow but hence the turbo, gotta start somewhere). I have heard that EGT's are what kill diesel engines so making it breathe better sounds best to do after the brakes no matter what just for reliability. -
#6 by Smoker on 08 Feb, 2016 05:22
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The 1.5 needs a turbo. A hill and a headwind will slow it right down.
Do it. I loved my 1.5 vnt-15. Engine is still going strong in my friend's car, without the turbo.
The reliable mechanical controller is pretty easy to build.
You do "need" headstuds.
The VNTs are cheap; under $250. That's including the exhaust manifold.
They are easy to rebuild.
They hang down so you can use a gasser intake instead of the restrictive (and sometimes hard to find and expensive) stock TD intake.
Gasser intakes are plentiful. Basically a free intake and exhaust manifold compared to the stock setup.
The exhaust is easier to build than stock because it easily clears the shifter.
They have a great sound. You can sit at a light and slowly rev higher,.. before your RPMs get too high the whine increases like it's going to blast off ziiinnnnnnngggggg. beyond hearing range then a second harmonic comes in and between the gears a big ol' BEWHUU.
They don't boost much above 18 but they are so fun at the low end.
Worst drawback in my opinion: It might be part of what is causing lower oil pressure than I would like. The 2 stock bearing surfaces are trimmed down to only about 3/16" of contact. New bearings have a little wider bearing surface. The bearing sits loosely into the housing, I don't think this helps with oil pressure, as oil can go around it.
I don't think the brass expands more under heat and seals around the bearing. Anyone know more about expansion rates of brass vs cast iron? Small, under 9/16" cylinder shaped bearing.
Pretty simple piece. I'm going to try to build/machine a better/tighter bearing. Inspired by a balanced turbo, new compressor wheel with too much clearance, need to ream a bearing to match the shaft if I want to save it.
Many people set them up wrong and give up.
Max turbo at idle and drop it off to almost nothing when floored.
I really should consider this for my mk2... I found 4 vnt's while cleaning out my garage the other day. Building a vane controller has always scared me off. -
#7 by Brystephor on 08 Feb, 2016 16:46
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If i was you, I would just buy a boost controller and install it by some other means. I had a 2003 wrx, running 18 psi until the mechanical boost controller broke open and ran it peaked to 30psi, new headgasket, studs, coolant every where. Not good.