Late series engine compatibility with earlier series engines?

I have a dream.

A dream that I can keep the top end of my N/A motor, Plenum and everything down to, but not including the heads (pending), and transplant a TT motor's bottom end.

Can this be done? I ask this because while trouble shooting the issues I will have when I attempt the TT transplant into my N/A, I've concluded that a traditional N/A to TT conversion will be hell on account of the HUGE amount of differences in the wiring loom.

Question two, as I have a later model motor, and these came with the "upgraded" heads (unsure of the name of them, off the top of my head, the earlier model heads are P40 and the later model are P48 ). Can I have the upgraded later model N/A heads machined or modified to suit my future TT motor?

That way, I would only have to change from the heads down to TT.

I'm sure my later idea has flaws that I can't see, hence the question, however the first question seems plausible to me.

Ideas, experiences, comments or anything else welcome and appreciated.

Cheers, Dean.

 

should all be fine

plenum upper and lower will bolt onto early series heads just fine.

the difference between the TT and NA heads is in the material the valves are made off, basicly the TT valves can handle the extra heat etc from turbos, so can the NA's but they will degrade over time. you could easily have the late series heads rebuilt to suit to be TT heads. i have heard that there are difference in the intake and exhaust ports, but so far i have only seen/heard heresay no proof to this end.

obviously your NA injectors will need to be swapped for TT ot better injectors.

 

I haven't kept up with the rules but isn't the 'motor must be of equal age or newer than the car' still applicable? Being a 97 this could be tricky.

Even if you swapped only the block (where the engine number is printed), you'd probably still need a late spec block since the engine number has changed and technically it's a different engine.

Then there's the added headaches of OBD2, newer loom, newer plugs and sensors. Honestly it'd probably be easier but expensive to source a late spec or better yet, 2k half cut preferably with the factory xenon headlights.

 

If you are going to run the T/T motor as an N/A one thing to consider is the lower compression because of the T/T pistons. You'll only need to bigger injectors when its turboed

 

I think jinxed is the only person that got me.

Mike, all the issues with OBD2 and looms would be avoided if I kept the"top"of my motor.

Lurker, my current N/A motor would be used and moddified to TT spec, meaning TT pistons, Rods, injectors, everything.

The plan is for a big hp TT motor to be made from my existing N/A motor to

1: avoid complecations with the loom
2: keep it still more or less a '97 motor

 

If you want to swap over that much it wouldn't be that hard to just retain your engine block Swap the internals, new rings and you will already have a gasket kit and head bolts from changing everything over. Will save a few headaches.

 

maybe ring vicroads and ask them if changing the block to one older than the car is an issue?

if so you might want to consider chrispy's suggestion and just swap the internals in your current block.

 

I don't really know that much about building a motor, didn't know it was possible to just swap the internals. Ill still be able to build it strong enough for any "off the shelf" turbo kit right?

Yeah I'm 99% certain I'm running OBD2, the reason I say this is because conzult doesn't work for me. I only get a few readings...

 

Just swap the oil squirters would be much easier.

 

I found out during the course of my build that my Block was an NA Block with, I'm assuming TT Internals. Ran just fine for years.

In your case I would choose to:
- Rip the motor out and tear it down
- Find out what condition the Block is in at a trusted Engine Machining Shop
- If good, determine the size of the Forged Pistons you need, buy them along with Forged Rods
- Buy new Valves, along with Springs & Cams if you wanna go that far
- (Buy any other needed things for TT Swap at this stage, from Injectors to Oil Tree... anything else you'll need)
- Have Machining Shop assemble the Block & Heads separately or even assemble it all in one go if you want
- Assemble the rest/entire Engine at home
- Drop back in
- ????
- Profit

And more or less exactly what I did, except I wasn't re-using my NA Block, already had a prepped TT Block lined up.

MoulaZX

 

OBD2 uses a different port to the regular consult plugs that the rest of us use for OBD1. Any *free* consult that you get is for OBD1 only, the only real thing you can do with OBD2 is read error codes, and they are different to all the ones we talk about here.

The OBD2 port looks like this.



The OBD1 port looks like this.

 

This will be an issue, either import a 99/2000 model engine or halfcut or rebuild your current engine as a TT.

 

I'll take a look at what my port looks like tomorrow, cheers.

I think the best option I have is to rebuild my current N/A motor as a TT.

This technically means that the car will still be an N/A to Vicroads as the VIN won't change... Not to mention that it'll also technically be a '97 spec TT. WOOO!

 

It will need to be re-registered as a TT but it will indeed be a 97 TT through and through.

 

Yeah exactly!

I think you misunderstood me... If it isn't re-registered as a TT, and I do get pulled over by the popo (P Plates), the rego will say N/A haha.

Not saying I'll be doing this, but something to think about for other N/A owners that want to go TT.

 

It will be a big job, you may well be allowed to drive it as a TT when you're done even if you start now.

 

Bahaha, hopefully that's not the case!

It won't take any longer to change the N/A components to TT that it would be to rebuild a standard TT motor anyway correct?

As in, throwing forged bits in a TT will follow the same process?

 

There is a bit more to it than that, new oil squirters for a start, valves, springs, pistons and rods and stuff are mostly just standard TT things but there are always lots of little things that come up along the way. I'm not sure if NA and TT heads are different, I've heard they are so it would be worth getting your heads mildly ported too just in case.


If you're just doing a standard TT rebuild you may be better off looking at prices for a late model TT engine to drop straight in, saves the cost of opening an engine up and such.

 

Standard TT rebuild it will not be!

Extensively ported heads, O/S valves, perhaps springs, forged bits to say the least.

Big ass rebuild plan, do it once, do it right. This motor will outlast me. Don't want to give everything away just yet though