Maximum psi?

[PSIKO]

Hey,
does anyone know the maximum the standard Montego turbos can produce safely (without shearing the shaft off, or running out of efficiency)? I have mine running at 0.8BAR at the moment (~11.76psi) but was wondering if I can push it as far as just under 1BAR (14psi)?

Also does anyone know much about the turbos - are they ceramic or steel wheeled? Do they have a Garrett t3 flange?

Cheers guys

[Mat_C]

The turbo is rated at 18psi max. - but above 14psi you may have problems with the head lifting off the gasket!

[PSIKO]

ok sweet as, cheers mate

otherwise, in terms of pinging and detonation the intercooler is fine?

[Mat_C]

Without getting too deep, the main problem with the intercooler is the end-caps blowing off - easily fixed by strapping together with a jubily clip etc.

[PSIKO]

ok cool, as long as it's not the end tanks blowing off!! :( haha

but as long as the intercooler can sufficiently cool the air charge at 14psi, then all's good!

[GK AutoWorks]

Originally posted by PSIKO
Hey,
does anyone know the maximum the standard Montego turbos can produce safely (without shearing the shaft off, or running out of efficiency)? I have mine running at 0.8BAR at the moment (~11.76psi) but was wondering if I can push it as far as just under 1BAR (14psi)?

Also does anyone know much about the turbos - are they ceramic or steel wheeled? Do they have a Garrett t3 flange?

Cheers guys

The standard Turbo can run up to 17-18psi but this is it's limit, at around 15 ish psi, it heats the air up too much so the power gain is not as big from 13-16psi than it is from 10 to 14psi. The head gasket will either hold very well like mine has done (125k on original item) or will fail quite quickly. You'll need to ensure your cooling system is A1 as a lot of extra stress is put on it in a higher state of tune.

The end caps on the intercooler can blow off at standard pressure, its happened to me! Strapping it gives a permanant fix to this problem. Above 14psi i would recommend sorting a bigger intercooler to decrease the risk of detonation you can experience if the inlet temps are too high. Good fuelling is essential too.

[Mike Brock]

To answer your question in short, 14psi is the up-most safest limit you can go before internal engine modification are necessary. Head gasket will be the main problem if reliability is the issue, you’ll need to copper ring the block if you want to run over 14psi. C/R will always be a compromise with boost pressure, ignition advance etc, and may need to be lowered if you want to run higher boost.

I wouldn’t run anymore than 16psi, dispite std turbos 18psi max. To free up a lot of power/torque, (25psi +) then a hybrid turbo is the only answer. BTW, the Monty turbo is fitted with a Garrett T3, so will have the flange of course. It's not ceramic either.

Other problems to sort out is the plenum chamber pop off valve (dump valve). This is designed to open at 12/13psi. Turbo boost pressure above this will be wasted to atmosphere if pop off valve is not modified.

Intercooler efficiency is around 48% at 10psi, obviously a bigger Intercooler must be high in the priority list. Consider TIG welding two Monty turbo Intercooler together!

Presuming you already have a performance exhaust system? - Exhaust down pipe has a restrictive collar in it (swivel ball joint) that needs to be opened up. The exhaust down pipe is the one connected to the turbine outlet elbow. This will free up exhaust back pressure, reduce exhaust temps, pinking etc - generally improve reliability.

Cooling system struggles as is (even more in Australia!). 3/4 core radiator highly recommended.

Clutch will need to be up-rated as it’s only good for 180bhp-ish apparently. - Oh yes an oil cooler is a must!!

Even with all the above mods life expectancy of the engine will be considerably reduced no matter what you do.

Mike Brock...

[PSIKO]

Thanks GK and Mike (very famous surname over here!)

I wasn't planning on going all out, pretty much jsut dial in a couple of extra psi and get it going nicely. But leave it at the cheap and nasty mods. It's only my runabout car over here (we used to have one in the UK so when I saw this one I had to have it :D), but I wanted to just get some nice power out of it
I think the carby needs to be adjusted a bit too as it's blowing black smoke/rich

Also wanted to put it on the 1/4 mile track, the Motorplex (http://www.motorplex.com.au), here and see what time she pulls heheh

Thanks for the long list Mike
damn about the oil cooler ... pretty expensive over here, would the cooper s cooler suffice?? I think the exhaust is standard though, it's VERY small, will have to have a look at the dump pipe; cheers for letting me know about the restrictor

Though, as I said I may just leave it at that, just checking whether it'll still be reliable after putting up the boost to approx 12psi that's all!

Thanks fellas!

[MGTurbo]

Originally posted by PSIKO
Thanks GK and Mike (very famous surname over here!)


I think the carby needs to be adjusted a bit too as it's blowing black smoke/rich

Also wanted to put it on the 1/4 mile track, the Motorplex (http://www.motorplex.com.au), here and see what time she pulls heheh

would the cooper s cooler suffice?? I think the exhaust is standard though, it's VERY small, ;

Though, as I said I may just leave it at that, just checking whether it'll still be reliable after putting up the boost to approx 12psi that's all!

Thanks fellas!

With regards to the carb, it could well be leaking O ring seals on the stepper motor (if still fitted) These would need to be replaced, the part number for them are BSO13 in Viton. Any good o-ring/seal supplier could sort you out for that one if they are past it, which most of them are by now if never been replaced!

Oil Cooler kits over here are not too expensive, but for the mild state of tune you intend you may as well a stick to a high quality fully synthetic oil changed regulary, even though you ambient temperatures are higher, unless your going flat out for quite a while, it shouldnt be too much of a problem IMO.

Standard exhaust IS small and should be disposed of! Your best route could well be a custom made item in SS of between 2.25/2.5 inch diameter. The downpipe as already mentioned is also poor, but good 1/4 mile times can still be had if you cannot afford to replace it.

I've been running between 12-14psi for a while now and its been as reliable as it was when on standard boost, running 12psi certainly isn't going to wear the engine out much quicker if looked after.

Gareth