max boost 14psi??

[frozen]

dawso - thats kinda what apc was saying too. i mean, they do have a 7 second evo... surely they know 'something' about power

edit - and about my earlier post - i say 15psi but i dont think i'd want to go much more than 12.. maybe 13 or 14 tops on stock turbos. ill see what i can get out of it.

 

[pu-11-me]

Hahaha.... Or they know something about cheating?

 

[Nash]

I will have to disagree with that comment about 17psi being inefficient. wtf would a bunch of Lancer evo clowns know about a totally different engine running intake and cooling modifications.

Once someone comes up with air temp/boost figures that prove otherwise I think we should try for 20psi......:tongue_smilie:

 

[whiteleg]

Craig don't want to sound rude but APC arn't 'Lancer evo clowns' they are very expericed mechanics and tuners. They get big power out of any type of car. I would rather take the knowledge and experince of those who have done the work before than take a guess and distroy your turbo/engine.

 

[Nash]

Craig don't want to sound rude but APC arn't 'Lancer evo clowns' they are very expericed mechanics and tuners. They get big power out of any type of car. I would rather take the knowledge and experince of those who have done the work before than take a guess and distroy your turbo/engine.

Just stiring the pot Matt. I am sure they are geniuses.

If they actually said go 15psi and not 17psi because it is inefficient, I would like to see the proof of that. Not disputing that they are really good at what they do, but just coming out with a comment like that about a car they have not had a lot of experience with is kind of cocky if you ask me.

I am not trying to start a fight or anything, just my two cents worth...

 

[SiliconAngel]

TBH it sounds like a simplification of a fairly complex topic, and one should always try not to oversimplify complex problems. As I said, running stock components sticking to 12psi is probably a sound principle, which I think is what they would have been getting at. But with enough (efficient) cooling and adequate supporting mods you can get the stock turbos to boost to 17psi before you reach the point of diminishing returns.

 

[jet150]

Yeah having the right components will help but remember the stock turbos are small, they will flow a certain amount of air. You can't just wind up the boost to 20 psi cos you have an exhaust, cold air, ecu and more fuel. If that was the case then no need for bigger turbos just use stock ones and wind the boost up on all cars.
Every turbo has it's limits and if you set boost to high for a small turbo it won't work efficiently at high or full boost. Thats why most people upgrade their turbos when they want more power. A bigger turbo than stock will most certainly run better if you want more boost.

Like I said in a previous post you can HI FLOW the stock turbos to get them flowing more air, then you can wind the boost to 18psi safely and efficiently.
A Hi Flow consists of changing the compressor wheel in the turbo, and you can also Extrude Hone your original turbo housing to make it slightly bigger.

Specialised Power Porting in Mt Helen Victoria can do these procedures.

 

[SiliconAngel]

Don't disagree on the point of max flow Rob, just stating that testing Brad and his tuner did found 17psi was about as much as the stock turbos should be taken to given the best possible scenario; beyond that was exactly as you said - pointless. Now that doesn't mean you won't be able to achieve higher sustainable boost faster with better turbos (like some little garret ball bearing GT2554R). Its just talking about what you can get out of the stock setup before you have to lay out five to ten grand for a turbo swap and manifold rebuild (and yes you can do it cheaper, but I prefer to do things properly ).

Regarding hi-flowing I'm fairly certain I've read of two people who high-flowed their stock turbos only to have them fail soon after, but TBH I have read so much about these cars in the past two years I couldn't tell you where I read that (although it was almost certainly on CVR4).

 

[jet150]

Cool, ill aim for 17 psi when I tune my car.

 

[frozen]

Craig - APC didnt say anything about 15 over 17, they simply said to me that while tuning my car with mostly factory everything bar catback exhaust (this was back when i had the SAFC tuned.. early last year) and they said that more than 12psi on my car would just be inefficient for what i had at the time. the 15 over 17 comment was what i was saying about what i will be trying. ill probably try 1bar when i get the rest of my pipework done and a new ecu.. cant see myself going more than that on the stock turbos.

 

[Guest]

Brad: When you have some down time take off the back manifold, ok alot of down time cause its not an easy task lol. When did I was greated by a manifold that was split in 3 sections, it was funny but it did explain a few things. It could be fixed but for my build it wasnt a good idea to cut corners there.


Does that .8 make a difference HELL YEA.. you can turn the boost up as high as you like but if the itty bitty 6c cant move the air its pointless. When I referenced 13.2 it was because I've spent hours on a dyno trying to find the absolute max power gains before they (the 6c's) would fall flat on their face around 6200 rpm if I can recall correctly.

Keeping the turbo's in there effective range or efficiency can determine having them make power across the power band or getting to a spot and falling flat. The little bit of HP/torque improvement you cant measure without a dyno, even with one its so small you could over look it if you really arent paying attention..

Having the intake, exhaust, fuel, fmic and all is great but its not going to drastically cool the air enough to make the 6c's work effectively, its just not going to happen. Mitsubishi has never been a car maker to ever over engineer anything, outside of the 4G63T everything is marginal

 

[godzilla]

I reckon that if you asked Bradc to wind his wick down 3.8 psi he would lose power for sure which would indicate that the 17psi that he his running is actualy doing something i.e. still efficeint enough with his current supporting mods.

 

[Guest]

I reckon that if you asked Bradc to wind his wick down 3.8 psi he would lose power for sure which would indicate that the 17psi that he his running is actualy doing something i.e. still efficeint enough with his current supporting mods.

maybe, maybe not. One thing is for certain, the 6c's loose drastic power anywhere between 5800 rpm and 6200 rpm. On any dyno sheet look when the power starts to dissappear lol its no big issue since the 6c's were not designed with race in mind

 

[bradc]

At 14psi my car was making about 210 or something I think from memory. The extra boost will help more at low rpm anyway, my car is fairly epic from 3000 to 5000rpm

 

[Guest]

At 14psi my car was making about 210 or something I think from memory. The extra boost will help more at low rpm anyway, my car is fairly epic from 3000 to 5000rpm

only 210? I was doing 222 awhp and 230's torque with my old setup running 13.2.

Exactly @ 3k to 5k

With the short gearing of our cars you can go through that power range so quickly that when you are on top end 160mph+ 5th gear is not doing anything put yelling at you to slow down lol

 

[Kenneth]

When you specify the maximum boost, you need to additionally specify the RPM at which you want to be running that boost, or else your statement is pointless.

For example, I can tell you my car ran 15.2PSI with no trouble at all. Stripped down the engine and it was perfect.
That statement makes more sense when I then say it peaked at 15.2PSI at 3000RPM and held close to 15 to 4500 and dropped steadily to about 12 at 5500 where peak power was made.

You can't just say "xxx.xx amount of boost is max for the VR-4"
Neither can you compare 2 cars and say that because x boost was the most you could efficiently get from yours, then that is the max across the board.

There is one fundamental reason for this. Turbos do not work in PSI/Bar etc. They work in pressure RATIO.

For instance, atmospheric pressure at sea level is 14.7PSI (close enough). In a perfect world, this would be the inlet pressure on the turbo.
If you then run 13.2PSI of boost , the pressure ratio is calculated as
( 14.7 (inlet) + 13.2 (turbo outlet) ) / 14.7 (inlet pressure) = ~1.9 (pressure ratio)
This of course can now be plotted on a compressor map.

It isn't a perfect world though. Due to intake differences and other things the inlet pressure will be less.
Lets say that you loose 2psi of inlet pressure do to intake restrictions (or whatever).
(12.7 + 13.2) / 12.7 = ~2.0 pressure ratio.

That doesn't necessarily mean a lot, so here is perhaps a more appropriate way of looking at it.
Instead of fixing the boost pressure (because this really is the variable bit) lets fix the pressure ratio, as this is what we need to use to plot our compressor efficiency.

We know that at about 2.4 pressure ratio (at max flow, which is what we want) is it for TD03s (if the available compressor maps are to be believed) after that, its all over.

A perfect intake with atmpsohperic pressure at the inlet:
14.7 * 2.4 - 14.7 = ~20.6 PSI on the outlet!

Remove a couple of PSI due to restriction
12.7 * 2.4 - 12.7 = ~17.8 on the outlet.

So, a drop of 2psi on the inlet ends up being a 2.8psi drop on the outlet. Nasty.

Thats without adding things such as temperature, turbo to manifold flow losses (intercooler, pipe work, throttle body etc), or just as importantly (if not more so), the exhaust.
The exhaust is subject to the same laws of physics as the intake, which is why adding a larger diameter exhaust is beneficial. It increases the pressure ratio of turbine inlet : turbine outlet.

So please stop arguing about what the maixmum boost is, technically (at peak flow, according to the compressor map) it is around 20psi, but you need a perfect intake for that

 

[bradc]

http://www.clubvr4.com/forum/uploaded/786/1204160395.jpg
http://www.clubvr4.com/forum/uploaded/786/1204160358.jpg

 

[Nash]

Craig - APC didnt say anything about 15 over 17, they simply said to me that while tuning my car with mostly factory everything bar catback exhaust (this was back when i had the SAFC tuned.. early last year) and they said that more than 12psi on my car would just be inefficient for what i had at the time. the 15 over 17 comment was what i was saying about what i will be trying. ill probably try 1bar when i get the rest of my pipework done and a new ecu.. cant see myself going more than that on the stock turbos.

My Bad

 

[Guest]

kenneth:
thanks but honestly just cause you can remember the equations doesnt make your comment any better. I can not find the efficiency map for the 6c's which shows the range the 6c's makes its worth.

 

[Sydo]

At 14psi my car was making about 210 or something I think from memory.

only 210? I was doing 222 awhp and 230's torque with my old setup running 13.2.

Are you two comparing KW and HP?