[Mk2] [Turbo] turbo boost pressure

[bigdave247]

hi all as per title i have a rev 2 turbo i know you can increase they boost but with stock head gasget not sure how far you can go and still be safe for gasget any advise

[alanmr2turbo]

up it to 1bar

[Ryan S]

As above, any more and the injectors are near at full duty anyway so I beleive

[bobhatton]

hi all as per title i have a rev 2 turbo i know you can increase they boost but with stock head gasget not sure how far you can go and still be safe for gasget any advise

I have been running 1.5 bar on my Rev 2 sprint car for the last 2 years but I did give the head bolts a further 90 deg turn and do run on 110 octane fuel.

With road fuel stock boost is the only safe way because there is always detonation when the boost is turned up and that’s when the gasket or ring lands go

[Peter Gidden]

Many owners have had no problems with the original fibre head gaskets, but many have.

As long as you accept the risk, go for it.

[craig]

I personally would replace the HG with a Rev3 Steel headgasket before upping the boost.

(personal view)

[bigdave247]

thanks for advise how does 1 bar convert into psi

[craig]

thanks for advise how does 1 bar convert into psi

1 bar = 14.5037738 pounds per square inch

[bigdave247]

ok great good to know i have one off them manual boost contolers and an after market boost gadge so just got to work out how to do it

[Turbonoz]

As above, any more and the injectors are near at full duty anyway so I beleive

440cc injectors are nowhere near at full duty regardless of how much boost you run through a CT26. 440s are good for well in excess of 300bhp on a 4 cyl 2L engine. Easily. I have a book here by Mr Jeff Hartman stating he achieved a maximum of 330rwhp (albeit USA-bred super horses) on the stock 440s.

[Ryan S]

As above, any more and the injectors are near at full duty anyway so I beleive

440cc injectors are nowhere near at full duty regardless of how much boost you run through a CT26. 440s are good for well in excess of 300bhp on a 4 cyl 2L engine. Easily. I have a book here by Mr Jeff Hartman stating he achieved a maximum of 330rwhp (albeit USA-bred super horses) on the stock 440s.

i stand corrected then, this was information i got off here years ago from a specialist

[Peter Gidden]

As above, any more and the injectors are near at full duty anyway so I beleive

440cc injectors are nowhere near at full duty regardless of how much boost you run through a CT26. 440s are good for well in excess of 300bhp on a 4 cyl 2L engine. Easily. I have a book here by Mr Jeff Hartman stating he achieved a maximum of 330rwhp (albeit USA-bred super horses) on the stock 440s.

i stand corrected then, this was information i got off here years ago from a specialist

Shame the major tuners don't agree. There isn't one major tuner in the US i.e. ATS, KO, RickyB etc that would dream of using 440s for more than 300hp. 99% sure RyanG wouldn't either.

Maybe JH was upping fuel pressure to about 60psi...

[rs007]

440cc injectors are nowhere near at full duty regardless of how much boost you run through a CT26. 440s are good for well in excess of 300bhp on a 4 cyl 2L engine. Easily. I have a book here by Mr Jeff Hartman stating he achieved a maximum of 330rwhp (albeit USA-bred super horses) on the stock 440s.

i stand corrected then, this was information i got off here years ago from a specialist

Shame the major tuners don't agree. There isn't one major tuner in the US i.e. ATS, KO, RickyB etc that would dream of using 440s for more than 300hp. 99% sure RyanG wouldn't either.

Maybe JH was upping fuel pressure to about 60psi...

Yeah, forcing fuel through them faster would be a crude way of making them still perform for higher HP targets - Peter, in your opinion, what is the max power you can get from a stock Rev 2 fuel system?

[Turbonoz]

440cc injectors are nowhere near at full duty regardless of how much boost you run through a CT26. 440s are good for well in excess of 300bhp on a 4 cyl 2L engine. Easily. I have a book here by Mr Jeff Hartman stating he achieved a maximum of 330rwhp (albeit USA-bred super horses) on the stock 440s.

i stand corrected then, this was information i got off here years ago from a specialist

Shame the major tuners don't agree. There isn't one major tuner in the US i.e. ATS, KO, RickyB etc that would dream of using 440s for more than 300hp. 99% sure RyanG wouldn't either.

Maybe JH was upping fuel pressure to about 60psi...

Haha, it's not a shame, it's just the way some people do things differently

I was talking 300bhp @ flywheel, and regardless of what anyone says, 440cc injectors support that and more on a 2L 4cyl engine at 3 bar base fuel pressure with 1:1 FPR, top feed & side feed, high impedance & low impedance. Playing with fuel pressure isn't exactly cheating either, Toyota 440s are rated as such at the base fuel pressure of 2.5bar (36-38psi). At the standardised 3bar (43.5psi) pressure that injectors are generally flow-tested at, they are actually 482cc. Nothing wrong with upping the pressure a bit to 3 bar and more (as long as the pump can cope, of course).

Jeff Hartman ran 300rwhp (377@fly, USA figures) with stock fuel system. The 330rwhp was using a twin-entry rail and BEGI VRG (Variable Rate Gain) FPR (or AFPR) in conjunction with the stock FPR, but he doesn't mention maximum pressure.

Maybe the Toyota 440cc are just pants for everyone else. Who knows

[Turbonoz]

Yeah, forcing fuel through them faster would be a crude way of making them still perform for higher HP targets - Peter, in your opinion, what is the max power you can get from a stock Rev 2 fuel system?

Hmm
Increasing fuel pressure is no more crude than increasing boost levels that a turbocharger produces, it's simply another method of altering the way a system behaves. I've run many injectors at 4 bar and not had any issues. Not because I had to, but to explore the way various changes altered the way an engine/car behaved as a whole. Obviously, changes need to be catered for properly in the EMS to get the full benefits. I've seen a couple of 1.8L CA18DETs hit 350bhp@fly on JECS 440s at 3.5 bar base pressure. No issues at all.

Over on the MKIV owners site is an experiment with the stock Supra injectors.

Yes there was a distinct difference in the spray quality as the pressure was varied. At the lower pressures (1.5 and 2 bar) the flow was mainly in two jets without much "spray." As the pressure reached 3 bar, the jets turned more into a cone of spray with better atomisation. At 4 bar it was even more pronounced - to the extent that I would be tempted to run 4 bar rail pressure before moving to "550 cc" injectors.

As a little bit of a play at the end I ramped the pressure to over 6.5 bar and saw a powerful cone of good spray when the injector was held open. When I tested it with a 50% duty cycle, the flow seemed to be much lower than at 3 bar (unfortunately I didn't get any measurements) suggesting that the dead time went through the roof. This would make them a nightmare to control.

Make of that what you will

[rs007]

Yeah, forcing fuel through them faster would be a crude way of making them still perform for higher HP targets - Peter, in your opinion, what is the max power you can get from a stock Rev 2 fuel system?

Hmm
Increasing fuel pressure is no more crude than increasing boost levels that a turbocharger produces, it's simply another method of altering the way a system behaves. I've run many injectors at 4 bar and not had any issues. Not because I had to, but to explore the way various changes altered the way an engine/car behaved as a whole. Obviously, changes need to be catered for properly in the EMS to get the full benefits. I've seen a couple of 1.8L CA18DETs hit 350bhp@fly on JECS 440s at 3.5 bar base pressure. No issues at all.

Over on the MKIV owners site is an experiment with the stock Supra injectors.

Yes there was a distinct difference in the spray quality as the pressure was varied. At the lower pressures (1.5 and 2 bar) the flow was mainly in two jets without much "spray." As the pressure reached 3 bar, the jets turned more into a cone of spray with better atomisation. At 4 bar it was even more pronounced - to the extent that I would be tempted to run 4 bar rail pressure before moving to "550 cc" injectors.

As a little bit of a play at the end I ramped the pressure to over 6.5 bar and saw a powerful cone of good spray when the injector was held open. When I tested it with a 50% duty cycle, the flow seemed to be much lower than at 3 bar (unfortunately I didn't get any measurements) suggesting that the dead time went through the roof. This would make them a nightmare to control.

Make of that what you will

Of course - but IMO it would only be akin to upping boost level of a turbo with a bleed valve or similar - I just meant it is crude because unless you have fully mappable management, you have no fine control (you did mention this tho), its just up everywhere. Bit like crimping the fuel return hose a little in the olden days, now that was crude

Using a electronic boost controller is of course a better way of controlling a turbochargers boost, and if we are continuing the analogy then surely the best way always to control fueling is by setting optimum fuel pressure - then by electronically controlling the injectors to control the fueling?

Higher pressure creating finer atomisation, that makes sense; when you pull the trigger moderately in one of those plant sprayers you get a fine enough spray - but when you pull it as hard as you can you get a much finer spray rs007 impenetrable logic

[Turbonoz]

Of course - but IMO it would only be akin to upping boost level of a turbo with a bleed valve or similar - I just meant it is crude because unless you have fully mappable management, you have no fine control, its just up everywhere. Bit like crimping the fuel return hose a little in the olden days, now that was crude

Using a electronic boost controller is of course a better way of controlling a turbochargers boost, and if we are continuing the analogy then surely the best way always to control fueling is by setting optimum fuel pressure - then by electronically controlling the injectors to control the fueling?

Higher pressure creating finer atomisation, that makes sense; when you pull the trigger moderately in one of those plant sprayers you get a fine enough spray - but when you pull it as hard as you can you get a much finer spray

Bleed valves are long gone, but a proper manual boost controller is a completely different animal. EBCs & MBCs: Which is best is debatable, I run both and my MBCs are spot on. Plenty prefer the MBC, with a properly specified spring, it is hard to beat. I run one on the Pulsar and one on the Zed. My Profec B came with a car I bought, so it gets used on my MR2 and is very handy due to the amount of mapping/testing the car sees.

Increasing the base fuel pressure is perfectly viable, but of course it needs to be remapped, that's not in dispute by anyone (unless someone has totally missed the point). It is completely separate from the mapping side of things from a control point of view, obviously there is interaction between the two systems (if base pressure increases, the pulsewidth constant needs to be reduced and latency increased, and then you look at load/RPM-dependent trim values). There is no analogy really, you can't increase base pressure electronically. It has to be done mechanically. The electronics comes afterwards. Not really sure what you mean by "optimum pressure" either. That would be dependent on how much fuel is required, obviously operating within the constraints of the fuel system capabilities (injector response & pintle design, fuel rail, pump specification etc).

If your fuel system can run high pressure with sufficient/acceptable reliability in a controlled manner, then you are simply maximising the potential of the current components by doing so.

Sorry, but I'm not really sure how to approach this from a different point of view.

[rs007]

Of course - but IMO it would only be akin to upping boost level of a turbo with a bleed valve or similar - I just meant it is crude because unless you have fully mappable management, you have no fine control, its just up everywhere. Bit like crimping the fuel return hose a little in the olden days, now that was crude

Using a electronic boost controller is of course a better way of controlling a turbochargers boost, and if we are continuing the analogy then surely the best way always to control fueling is by setting optimum fuel pressure - then by electronically controlling the injectors to control the fueling?

Higher pressure creating finer atomisation, that makes sense; when you pull the trigger moderately in one of those plant sprayers you get a fine enough spray - but when you pull it as hard as you can you get a much finer spray

Bleed valves are long gone, but a proper manual boost controller is a completely different animal. EBCs & MBCs: Which is best is debatable, I run both and my MBCs are spot on. Plenty prefer the MBC, with a properly specified spring, it is hard to beat. I run one on the Pulsar and one on the Zed. My Profec B came with a car I bought, so it gets used on my MR2 and is very handy due to the amount of mapping/testing the car sees.

Increasing the base fuel pressure is perfectly viable, but of course it needs to be remapped, that's not in dispute by anyone (unless someone has totally missed the point). It is completely separate from the mapping side of things from a control point of view, obviously there is interaction between the two systems (if base pressure increases, the pulsewidth constant needs to be reduced and latency increased, and then you look at load/RPM-dependent trim values). There is no analogy really, you can't increase base pressure electronically. It has to be done mechanically. The electronics comes afterwards. Not really sure what you mean by "optimum pressure" either. That would be dependent on how much fuel is required, obviously operating within the constraints of the fuel system capabilities (injector response & pintle design, fuel rail, pump specification etc).

If your fuel system can run high pressure with sufficient/acceptable reliability in a controlled manner, then you are simply maximising the potential of the current components by doing so.

Sorry, but I'm not really sure how to approach this from a different point of view.

Oh my we are thorough at this internet game arent we x

I'm not actually disagreeing with you, but a couple of answers to points you made - by optimum I simply meant, look at the quote you posted to support your point - it clearly stated that spray pattern became ineffective and hard to control at higher end pressures.

Obviously at lower pressures, spray might not be as finely atomised.

There is a middle ground, and that is what I meant by optimum, nothing more, nothing less. Where you lie in that middle ground is, as you also state, down to your requirements and acceptable reliability.

And I know bleed valves are more a thing of the past, it was simply to illustrate my point - you may run MBCs (got one myself) but you cannot deny that you can get finer control of more variables through an EBC (note this is apart from saying one is better than the other), thats all I was saying, an MBC IS a more crude way to increase boost by definition - wasn't intended to start a tangent O/T discussion

I know there is no way to electronically increase pressure, that isn't what I was saying, I was saying to increase fueling. Well, thats what I was trying to say

If your fuel system can run high pressure with sufficient/acceptable reliability in a controlled manner, then you are simply maximising the potential of the current components by doing so.

Totally agree, who could disagree - I simply said upping the pressure was a crude way of increasing fueling, perhaps not the best wording on my part

I'll say primitive then

pmsl

But obviously what we do when tinkering/building is take something, and try to optimise it within its capabilities, reliably - but that concept - reliability - is elastic even - for you and your requirements, upping your pressure to those levels is fine, nothing wrong with that - for me, with my car also being an every day driver, not so much possibly and similarly what is perfectly viable for you, may be a crude solution to the next guy and vice versa.

All just ways to skin the cat - Chill, tis only the web

[Turbonoz]

Oh my we are thorough at this internet game arent we x

I'm not actually disagreeing with you, but a couple of answers to points you made - by optimum I simply meant, look at the quote you posted to support your point - it clearly stated that spray pattern became ineffective and hard to control at higher end pressures.

Obviously at lower pressures, spray might not be as finely atomised.

There is a middle ground, and that is what I meant by optimum, nothing more, nothing less. Where you lie in that middle ground is, as you also state, down to your requirements and acceptable reliability.

And I know bleed valves are more a thing of the past, it was simply to illustrate my point - you may run MBCs (got one myself) but you cannot deny that you can get finer control of more variables through an EBC (note this is apart from saying one is better than the other), thats all I was saying, an MBC IS a more crude way to increase boost by definition - wasn't intended to start a tangent O/T discussion

I know there is no way to electronically increase pressure, that isn't what I was saying, I was saying to increase fueling. Well, thats what I was trying to say

If your fuel system can run high pressure with sufficient/acceptable reliability in a controlled manner, then you are simply maximising the potential of the current components by doing so.

Totally agree, who could disagree - I simply said upping the pressure was a crude way of increasing fueling, perhaps not the best wording on my part

I'll say primitive then

pmsl

But obviously what we do when tinkering/building is take something, and try to optimise it within its capabilities, reliably - but that concept - reliability - is elastic even - for you and your requirements, upping your pressure to those levels is fine, nothing wrong with that - for me, with my car also being an every day driver, not so much possibly and similarly what is perfectly viable for you, may be a crude solution to the next guy and vice versa.

All just ways to skin the cat - Chill, tis only the web

Sorry, I don't quite follow, thought we were having a technical discussion

I'm perfectly "chilled", emotions have nothing to do with anything I post. I'm not quite sure what you're on about now, and I'm only really interested in empirical findings, not verbose passages with no technical merit. Everything that I have posted is borne from having done it myself or witnessed it being done on a variety of vehicles for the last decade or so. And of course thorough research from reputable sources, something that my engineering background necessitates.

It was not my intention to enter into a lyrical cock fight regarding semantics. If my posts come across as coming from anything but a technical standpoint, something is wrong with 'the internets'. Regardless, upping the fuel pressure is neither crude nor primitive, it is a viable solution. Please explain to me why it isn't, knowledge is great and I am constantly on the hunt for more, I'm just not interested in posting b0ll0cks for the sake of it

[rs007]

Sorry, I don't quite follow, thought we were having a technical discussion

I'm perfectly "chilled", emotions have nothing to do with anything I post. I'm not quite sure what you're on about now, and I'm only really interested in empirical findings, not verbose passages with no technical merit. Everything that I have posted is borne from having done it myself or witnessed it being done on a variety of vehicles for the last decade or so. And of course thorough research from reputable sources, something that my engineering background necessitates.

It was not my intention to enter into a lyrical cock fight regarding semantics. If my posts come across as coming from anything but a technical standpoint, something is wrong with 'the internets'. Regardless, upping the fuel pressure is neither crude nor primitive, it is a viable solution. Please explain to me why it isn't, knowledge is great and I am constantly on the hunt for more, I'm just not interested in posting b0ll0cks for the sake of it

Good grief

I was having a giggle mate, especially with the use of the word primitive - you can have a perfectly good technical discussion and still include a little banter/humour. No willy waving here (mine is tiny and I don't know as many big words as you anyway )

*note smillie; used to denote good humoured banter*

Something that does seem to be sadly lacking from many an internet forum, car based ones especially - odd - I'll try to get into the Vulcan mindset lol

As you all were gentlemen!