Author Topic: To turbo or not (Read 2888 times)

bvolks73 · « **on:** May 12, 2007, 10:26:33 am »

I'm getting ready to change the head on my 85 Jetta (with an 84 Rabbit engine). I'm quite sure I have a bit of a head gasket leak because the coolant is pressurizing enough to puke some out from time to time even though it never runs hot and I'm sure there was some damage done to the head when it jumped it's time this winter. It just hasn't been the same since. So just replacing the gasket and reusing the head isn't an option. I have the solid lifter head that came on the original engine and it looks pretty good but there is a bit of marking on one of the camshaft "bearings".I'll try to get a pic and post it. I also have a solid lifter turbo head and turbo and a couple TD engines for parts so I have everything to switch it over. I've searched and read about using turbo heads on NA engines but I'm getting mixed opinions. I'm hoping to get some feedback from some of you guys who have actually done it and hear the good, bad and the ugly of how it turned out. I have a lot of travelling to do within the next couple months and really don't want to have to drive the gasser so I've got to get it done really soon. If I could gain a bit more power by switching it over to turbo without blowing it up I'd like to do it. Also, I would like to replace the valve guides. Is that a DIY type thing or does it have to be done at a machine shop?

RabbitJockey · « **Reply #1 on:** May 12, 2007, 10:29:54 am »

a solid lifter td head will bolt directly on a solid lifter na block, in form it's exactly the same, it's just a different alloy and different valves. you should be able to turbo it with out any issues... but if you have td blocks, you might as well use one.

bvolks73 · « **Reply #2 on:** May 12, 2007, 11:12:35 am »

I do have 2 complete hydraulic lifter TD engines but I imagine they would need re-ringed at least. One will only start on a push no matter how warm it is and the other one starts up fine but doesn't seem to be firing on #3 cylinder. I do plan on overhauling one of them at some time but a complete overhaul just isn't in the budget right now. I just want to make it reliable again and hopefully get my fuel economy half decent again. I'm only getting around 40 mpg now and I was getting close to 50 mpg before it jumped it's time. The reason I want to just replace the head is that I'm quite sure the bottom end is really good. It starts good in the winter down to -15 C and had as much power as any diesel I've had so I don't think it's low in compression. I just can't afford to do a complete rebuild on one right now.

tylernt · « **Reply #3 on:** May 12, 2007, 09:26:08 pm »

What you will be missing are piston oil squirters. Your pistons might get too hot in periods of sustained boost. Maybe you would be ok if you kept your foot out of it, and/or dialed down the wastegate to let it open sooner... dunno.

Darth Garry · « **Reply #4 on:** May 14, 2007, 02:50:26 pm »

If you're going to do a lot of traveling, reliability will be concern. Running a turbo on an engine not designed for it would be a bad idea, unless, like they said above, don't boost too hard/long. Personally, I would not risk it, and if you do decide to take a chance, invest in a good pyrometer and boost gauge.

Come to think of it, a pyrometer would cost about how much $$ you need to rebuild the bottom end of a turbo engine.

Another concern, if you do go turbo, you'll have to find/fabricate a new downpipe, relocate your fuel filter and do something with your air intake, so if you're short on cash, can't weld, and short on time, it may be too much to take on.

But you could, with no problem put a turbo head onto a non turbo block provided it's the same pursuasion (solid lifter block/solid lifter head), or (hydraulic block/hydraulic head).

Garry

burn_your_money · « **Reply #5 on:** May 14, 2007, 06:19:52 pm »

Quote from: "Darth Garry"

Another concern, if you do go turbo, you'll have to find/fabricate a new downpipe, relocate your fuel filter

I don't know about that... it's been a while since I saw a NA but I beleive the DP and FF are the same

bvolks73 · « **Reply #6 on:** May 14, 2007, 08:14:40 pm »

I have 3 spare turbo downpipes, intakes, etc since I have 3 TD's junked out already and can weld but I have decided against turboing it. I'm going to disassemble my turbo head and have a look at it. If it's better than what I have I'll use it but without the turbo. If it looks bad then I'll use the one I have now off the 1985 motor. Reliability is more important to me than extra power right now. I've lived without it for 11 years so a few more months won't kill me. I talked my brother into selling me his spare spare TD engine if the compression is OK so I may be going turbo sooner than I'd planned anyway. Nobody ever answered my question about valve guides though. Can you do it yourself or is it a job for a machine shop?

tylernt · « **Reply #7 on:** May 14, 2007, 08:18:22 pm »

You should be able to replace the valve guides yourself if you have a press. Can't remember if they come out and go in the top or the bottom though, hopefully the Bentley says.

Oh and the FF flange is the same but is on the passenger side on N/A and on the firewall near the GP fuse on turbo, as the turbo airbox and tubing occupies the passenger side of the engine bay.