Boost Pressures??

[HotFourOk]

Hey guys,

I'm getting a new exhaust fitted soon and want to know what sort of PSI figures have you guys ran in your Rockys.
I know they are quite strong, but not sure how much boost is too much boost.

The exhaust will give a few extra psi (thinking of 2.5" straight though), and i was then thinking of fuelling it up a bit and playing around with the boost settings.
It has 11psi stock, which I thought was quite high for a stock Rock (but I know this is the correct factory pressure).

Will the extra boost give a whole heap of gain, or just cause undue stress on the motor... I know its not a performance motor, but any extra power is always nice to have

I have heard that winding the pump up can give very good results, can anyone confirm this?

Did you run more than stock in yours Layto??
What about you aftermarket turbo guys, how much are you currently running??

Cheers for your help,
Nick.

[lay80n]

Round 15-16PSI, and played with the pump a bit to get some more fuel into it.

Layto....

[Big-Stu]

I got me one of them stock standard intercooled turbo diesels and it runs at 13psi boost. What more can I say.

Stu

[HotFourOk]

13psi is good... mine is only 11psi

Hopefully I gain a few psi with the exhaust and I hope to end up around 15psi like laybon said (boost controller also)

I might get a diesel tuner to do the fuel and whatnot, using an EGT.. probably safer that way.

[lay80n]

I just used a bleed valve. Being a ricer at heart you will know what i mean Nic.

Layto....

[HotFourOk]

I already bought one at the start of the year laybo
(One of the first things I bought for the Rocky...LOL)

I bought one of them ones off eBay.. the Turbotech ones... we'll see how it goes. Just never got round to putting it on.

[Spartacus]

look there VVVVVVVVVV

[Spartacus]

can your guys keep a secret???

im gettin my fuel cranked and running highest boost i can...
i want a new driveline sooner.

so ill let your no what the boost guage is reading once it comes out of the workshop...secret squirrel shiat

[lay80n]

can your guys keep a secret???

im gettin my fuel cranked and running highest boost i can...
i want a new driveline sooner.

so ill let your no what the boost guage is reading once it comes out of the workshop...secret squirrel shiat

I hope that wastegate is welded shit Though before you blow your driveline, you will probably cook your motor from too rich a mixture.

Layto....

[Spartacus]

I hope that wastegate is welded shit

the wastegate dont work supposedly

[tabrocky]

The exhaust will give a few extra psi (thinking of 2.5" straight though), and i was then thinking of fuelling it up a bit and playing around with the boost settings.

I might be wrong but, won't the exhaust make no difference to boost pressure as it's set by the waste gate actuator? It would allow it to spool up quicker though I reckon.
If i'm wrong can someone set me straight.

If your playing with the fuel keep a good eye on those EGTemps. You don't want those pistons going molten now...

I'm still waiting for the Daihatsu slow boat from japan to get mine on the road.
Have you disconnected that P.C.S. valve yet to see if it made any difference to first gear boost?

Cheers.

[lay80n]

The exhaust will give a few extra psi (thinking of 2.5" straight though), and i was then thinking of fuelling it up a bit and playing around with the boost settings.

I might be wrong but, won't the exhaust make no difference to boost pressure as it's set by the waste gate actuator? It would allow it to spool up quicker though I reckon.
If i'm wrong can someone set me straight.

If your playing with the fuel keep a good eye on those EGTemps. You don't want those pistons going molten now...

I'm still waiting for the Daihatsu slow boat from japan to get mine on the road.
Have you disconnected that P.C.S. valve yet to see if it made any difference to first gear boost?

Cheers.

Usually if you replace a restricitve exhaust with a free flowing on a turbo car, you pick up a few PSI due to the reduced back pressure allowing more efficient flow through the turbo. Pretty much all the turbo charged cars that i have worked on or owned (including F75) have done this. The exhaust flow increase and lack of pressure, allows more efficient opperation of the turbo, getting better spooling, and most of the time a Psi or 2 extra.

Layto....

[HotFourOk]

Yeah, I was just going on what Laybon said

I'm not sure if my car has the PCS valve in operation or not

I have tested it, and I get the full 11psi in first gear. Have you had a boost gauge on at all to see what the PCS restricts it to?

I am getting full spool, but I'm not sure if it allows it to boost more slowly??

Also, have you got an idea as where to remove it from?

[tabrocky]

Usually if you replace a restricitve exhaust with a free flowing on a turbo car, you pick up a few PSI due to the reduced back pressure allowing more efficient flow through the turbo. Pretty much all the turbo charged cars that i have worked on or owned (including F75) have done this. The exhaust flow increase and lack of pressure, allows more efficient opperation of the turbo, getting better spooling, and most of the time a Psi or 2 extra.

Layto....

Thanks for that.
I know decent exhausts are worth there weight in gold but didn't think it'd make much difference... in theory.
I guess like all things, in practice is a different story. This'll be the first turbo vehicle i've owned so i only know what I've seen and read.
Plan to replace the factory exhaust with a 2 1/2 or 2 3/4 inch straight thro' with a hotdog or two some time soon.
Has any body done this to the turbo ones? (off topic I know... sorry). My only concern is noise.
I would like a nice turbo shrill, and a slight amount of rumble but not so as it droones on the highway.... any suggestions?
My n/a F75 has extractors and a straight thro 2 1/2 inch with staright thro' muffler. The "loud pedel" has true meaning and it sounds mean, but gets a bit taxing on long drives. I know the turbo does a fair bit to muffle the noise so any experience appreciated.

Cheers.

[tabrocky]

Yeah, I was just going on what Laybon said

I'm not sure if my car has the PCS valve in operation or not

I have tested it, and I get the full 11psi in first gear. Have you had a boost gauge on at all to see what the PCS restricts it to?

I am getting full spool, but I'm not sure if it allows it to boost more slowly??

Also, have you got an idea as where to remove it from?

I was going to wait to try it on mine before I gave advice, but as it has taken so long to get it sorted....
Easiest (and most agricultural) way to disconnect it is to simply pull of the small rubber vacuum line to the PCS valve assembly (the round thing that clips onto the inlet manifold). You will need to plug the disconnected hose with a screw or something otherwise your vacuum will drop and you may loose vacuum assistance to you brakes.

The other way is to disconnect the power supply to the electric valve located near the windscreen washer bottle and voltage regulator. If your vehicle has Air cond there will be two of them (the other one is for the "idle-up" vacuum diaphragm). Just follow the hose from PCS valve to work out which one. Then, on the same solenoid you will need to swap one of the vacuum connections around as its "normally ON" when power is NOT applied to the valve. To do this, pull the plastic/rubber filter/bung thing'y (not sure of the technical term) from one end of the electric valve and swap it over with the vacuum supply line connection to the valve. What this all does is by disconnecting the power from the solenoid you make sure it is never activated, then swapping the connections over it makes it so that vacuum is NOT permanently supplied to the PCS valve.

As I said I havent tried it, but highly doubt it would cause any problems to. I'm guessing it'll either make no difference or some difference. You will need to find a very steep hill that you can really load the engine up in first gear to test if it has really made any difference.

Both methods are reversible if need be.

Let me know how you go. If it's any good I'll post some photos of the steps when I try it on mine.

Cheers.

[HotFourOk]

I recently got a 2.5" exhaust fitted and it goes sooo much better now, especially up higher in the rev range. Before it used to be quite slow around 3k onwards, not it happily will go to redline if pushed (remember it is an old clunker diesel ).
The boost reading has increased by maybe 0.5-1PSI... not enough to worry about.. but the extra power is huge.

Today I also plugged up the hose from the inlet manifold to the bypass valve of the PCS, and first gear power is greatly increased.
The front end lifts up near the end of first now, where it used to just putt along. The boost pressure has stayed the same after doing this, due to the PCS only dictating the fuel amount introduced into the motor, not boost pressure. So by doing this, more fuel is delivered in first gear, and more fuel = vroom vroom.

I'll update with more as I know.

[Big-Stu]

I got me one of them stock standard intercooled turbo diesels and it runs at 13psi boost. What more can I say.

Stu

After I quoted this 13psi figure from memory, I thought I had better just check it again on a long run. It actually runs at 9.5psi so I must have been dreaming up the other figure.

Stu

[tabrocky]

Excelent HotFourOK.
I'll have to play around with that PCS valve when I get back to SA. Sounds like it will be a good mod, especially for off-road. Yeah, your right about the fuel increase as the PCS valve acts on the union T piece which supplys pressure to the fuel compensator on the injector pump.
Did you notice if you get any extra exhaust smoke from doing this?
I don't expect you would because the turbo should still be able to supply plenty enough boost to keep the mixture lean. It does in every other gear when PCS isn't activated so I wouldn't expect first to be any different.... Any thoughts, observations?

As ive been over in WA since december, both Rocky I and Rocky II have been collecting dust at my parents place. Only got the last part from Daihatsu to sort the timing belt issues, 2 days before I left so poor little bugger hasn't been run for damn near 6 months all up. Rest assured I know it'll start first time.... when I put a battery in it.

Might make a new exhaust more of a priority now too. What type of muffler did you fit? Hotdog or normal? No muffler?

Cheers.

[mrRocky]

My 1989 td Rocky 15 psi standard with 3" zorst no muffler
tuned to 20psi by ovaboost performance in perth
thats the limit for the standard turbo.

A high flow turbo will produce same power figures with more top end at a lower boost than standard

[HotFourOk]

20PSI

Did you do any mods besides turning the fuel pump up and exhaust?

That would make it hop along nicely...

What can the DL-52 motor handle in the terms of boost?

[mrRocky]

Fitted big front mount intercooler (get out the grinder)
had the pump ajusted on the dyno
awsome on road and rocks yet to test it on the sand

even with 3" zorst with no muffler i still have 0 boost before 2000rpm
think i need a ballbearing turbo

Other car is a 3 tone bronco. Had to tow it 34 kms on a 1 ton car trailer
towed it ok just . Exept for the lag

[RockyF75]

Other car is a 3 tone bronco. Had to tow it 34 kms on a 1 ton car trailer
towed it ok just . Exept for the lag

Thats so illegal it makes saddam look like a saint



Not that i'm judgin you, just found it ammusing .... and am glad your in another state

[HotFourOk]

even with 3" zorst with no muffler i still have 0 boost before 2000rpm
think i need a ballbearing turbo

Does the front mount give it lots more lag?
Mine starts to see boost at around 1400rpm, and maxes out at 11psi by 1900rpm or so.

Pics I wanna see the big front mount

[iamnat666]

My 1993 F75 has boost turned up to 15psi and a Cone K&N Air filter, I've also disconnected the valve that Lowers the boost in 1st gear, much better when towing!
I'm wanting a full width Intercooler next, and I definately need to turn up the pump.

Anybody got any instructions on how to turn up the pump?

Thanks, Nat

[mrRocky]

U need to have the pump turned up on the dyno so they can check the mixtures and egt's. Dont just turn up the boost it needs to be done in conjunction with the pump, or ...........KABOOM
dont expect to fit a bigger cooler with aircon stiill connected or without breaking out the grinder.

[iamnat666]

Air con? Whats air con?

Too cold in the UK for that most of the time!

I was just wondering if anyone has any rough instrauctions on turning up the pump, as getting a use of a Dyno isn't easy!

The Landrover Guys seem to get away with just turning it up..

And fitting an EGT.... hmmm

I don't think mine will be too lean with the higher boost either because the pump is still going to be compensating same as normal....

[HotFourOk]

Better lean than too rich iamnat666... Diesels get hotter with overfuelling unlike a petrol which gets hot when running lean.

The consensus on the fuel pump (all models) is get someone to do it properly for you to save any trouble.