280zx turbo - non turbo

[glyn]

I've got a 1979 280zx which has a Janspeed turbo fitted(which was on when i bought it) and its been totally useless since i got the car so i want to remove the turbo and put it back to standard, is it as simple as taking the turbo off and putting the original ecu back on?
I've tried everything to get the turbo to work properly such as fitting a Greddy pop off valve but with no joy, it just won't boost up so my only conclusion is its buggered, i have been told by many people that the Janspeed turbos are as old as the ark and were crap when they were new.
I don't have the money to fit a different turbo so i thought i would remove the turbo altogether, once the turbo is removed would there be any benefit to fitting a larger throttle body and cone filter just to liven up the throttle response?
What would be sensible mods to do without having to spend thousands?

 

[Chas]

I've got the janspeed turbo on my 280ZX, all works well. Have you thought about having the turbo reconditioned? The turbo should be easy enough to remove as it bolts on to the original exhaust manifold, then the exhaust will have to be modifield to fit. I don't think the ECU would have been changed, as the Janspeed turbo was just a bolt on item. I ran my car with a large throttle body and K&N cone filter with and without the turbo. If you remove the turbo, and would have to modify the exhaust, you could look at getting a 6 branch manifold.

If you remove I may be interested in the pressure sensors, if they are working ok, also the greedy pop off valve.

 

[glyn]

Yes no problem let me know what you want, i've also got a purpose built alloy rad and intergrated intercooler if thats any good.
I assume you have a boost guage on your car and if so what does it go up to, the best this does is -1, which means there's no boost at all and when i fitted the greddy it made no difference,

 

[AndyMinto]

Glyn,
Might be a good idea to do a cylinder compression test as some of these turbos had the compression ratio lowered and are able to take more boost (mine has it lowered to 7.4:1). My boost gauge reaches a value of 18 in/Hg vacuum to + 7 PSI. Mine also has the standard JS blow off valve at the end of the J pipe. Are you sure the boost gauge is working properly and have you checked the jointing hoses for leaks?
Out of interest, where does the breather pipe from the top of the rocker cover go as there seem to be many different routes that were settled on. This latter question has nothing to do with turbo performance, it is just that I'm curious.

If you are going to un-turbo it then I might be able to help with the exhaust off my breaker (for a consideration)

 

[glyn]

The boost gauge is new and it just doesn't feel like its boosting anyway, its very flat. It made no difference when i put the Greddy on and that goes up to 11psi. It has steadily got worse and now it just doesn't seem to be doing anything and whats worse its only doing around 15mpg.
I don't have the money to spend getting the turbo reconditioned so thought it would be better to just remove it. Another problem is it was a reconditioned unit that was fitted(i have the original receipt) so i don't know if it was any good from the start.
Did your turbo make much difference when you first put it on?
And yes the exhaust downpipe would be very handy if i do put it back to norm.

 

[Mr.F]

When the Janspeed system was new it increased horsepower by about +30% over stock and made the 280ZX respectably lively. Although the technology is now old fashioned by comparison to modern turbos, it still did a very effective job and was quite highly praised by the motoring press.
I would investigate where your system is going wrong rather than simply junking it.

 

[AndyMinto]

I totally concur with Mike (Mr F). Also have a look at the attachments I put up on the other thread here MPG.

 

[Mr.G]

Yes, something is wrong somewhere Glyn, you should see the boost gauge rising. Your boost gauge should rise when you accelerate hard, if it's not then you are not developing boost either due to air leaks in the system or your turbo is not developing any pressure.

Check for any air leaks and ensure all rubber couplings are on tight and are not perished. I would also remove the rubber intake pipe from the turbo and check the turbo shaft for movement, there shouldnt be much side to side give.

Also the ECUs did not have to be modified, the kits were designed to be a bolt on installation. Some kits may have used a supplementary injector mounted onto the Janspeed J Pipe, and this was activated not by the ECU but by pressure sensing switches mounted into the intake manifold.

Can you please post up some photos of your setup.

 

[AndyMinto]

Like this?

 

[Mr.G]

Andy, does your J pipe have only one cold start supplementary injector installed or two?

Link below is a simple picture of the system, as you can see not a lot to go wrong with it. Check the rubber couplings and then the turbo.

JANSPEED TURBO

 

[glyn]

I'll take some pics tomorrow and post them up.
I have checked all the pipes and everything seems fine so while i'm taking the pics i'll check the turbo.
i have been struggling with this for a while now so am ready to rip it off and kick it around the garden.
Thanks to all that have replied, i hope you can stick with me and check out the pics tomorrow.

 

[AndyMinto]

Mr G.
It has two but they are not cold start injectors. The add additional fuel under boost to prevent pinking. One opens at 1 PSI and the other at about 4 PSI. I have LEDs wired to them into the dash so I know they are working.

Hope this helps

 

[Mr.G]

Hey Andy,

Familiar with them, that is my kit in the drawing. My injectors are of the cold start type and as you say are triggered by the boost sensing switches, which I've been told are hard to get now. Also discovered that some had a single injector controlled by a Microdynamics AIC module. The evolution of the Janspeed kit I guess...

 

[AndyMinto]

Mr G
There is a boost switch shown in the current Demon Tweeks catalogue but I am not sure how suitable it is. I managed to get a replacement recently from Application Engineering in Uckfield Sussex if that is any help. The replacement is more plastic than the original 1 PSI switch and needs protectiong from heat as this closes the contacts over fueling the car.

Hope this helps.

 

[glyn]

Ok here are the pics of the turbo, everything seems to be ok.
In reply to Andyminto, the breather goes to the throttle body, not sure if you can see it clearly in the pics.

 

[Mr.F]

1. Rocker breather on Janspeed system is normally extended forward to a spigot on the air filter or other pre-turbo air flow source. Unless you have a valve in your system, the rocker cover/crankcase is being subjected to turbo boost.
2. Where is the return end of the throttle by-pass system connected? I can see the hose dipping down under the manifold, but not where it is connected to. This cold start mechanism should allow a small air bleed from ahead of the throttle plate into the manifold when cold to supplement the cold start valve additional fuel. Always worth checking that the by-pass valve is shutting when hot..
3. Your PCV hose (which I'm assuming is connected to the pipe at the front of the block) is running too close to the turbo - relocate behind your heat shields.

 

[glyn]

The hose goes to the front of the block, its not as close to the turbo as it looks in the pics but i will move it behind the heat shield.
There is not a valve in the breather so your right it will be getting boost, can i re-route it to somewhere else or should i fit a one way valve?

 

[Mr.F]

The rocker cover breather needs to be extended to either a spigot welded to the end of the air filter box or to spigot on a connector pipe between air filter and air flow meter or between air flow meter and turbo inlet.

What about the throttle by-pass valve arrangement?

 

[glyn]

The pipe nearest is the breather pipe and the one behind goes to the air flow valve, in the second pic is the connector on the turbo pipe inlet which goes to the air flow valve so could i put a T piece on it and run the breather from that?
Plus what is it you need to know about the throttle by-pass valve?

 

[glyn]

Right i've taken off the turbo inlet pipe today and stuck my fingers in and there is no play in the turbo but i can't turn it at all, it is solid, i'm assuming it should be nice and free and be easily turned by hand. I can only imagine that the turbo bearing has gone.