Safe boost pressure....

[AlanDITD]

Ok quick question, sorry for hijack. If my plugs were gapped incorrectly i.e to wide. Could this cause the egine to be running hot on more boost?

[Nick Mann]

There is no such thing as a safe boost pressure. "Safe" is down to an individuals interpretation.

1. Safe could mean you have no detrimental effects on your turbos whatsoever.
2. Safe could mean the engine doesn't immediately let go.

In scenario 1, don't turn the boost up at all. In fact, sell the VR4 and buy a V6. This is the thing that not many of us advertise - turning up the boost will at best reduce the life of your turbos. In scenario 2, turn it up until you hit fuel cut and then keep your fingers crossed that the fuelling is still acceptable.

The only "safe" answer is to go to a rolling road, and monitor knock & afr whilst turning the boost up. You'll at least be able to quantify how safe you are being.

Having said all that, the optimistic gambling man on here would go for 1.0 bar of boost as a safe max. The pesimistic gambler would be around 0.8 bar. But both would be gambling to a certain extent without monitoring the health of the engine whilst boost is increased.

[Nick Mann]

Ok quick question, sorry for hijack. If my plugs were gapped incorrectly i.e to wide. Could this cause the egine to be running hot on more boost?

I'm no expert on this, but a large plug gap and high boost would probably lead to blow out/misfire I think? I'm not sure how this would lead to high temps.

[AlanDITD]

I'm no expert on this, but a large plug gap and high boost would probably lead to blow out/misfire I think? I'm not sure how this would lead to high temps.

Ok cool wel i just went and pulled all my plugs out with the intention of changing them if knackered but to check the gap. They all seem fine anyway im no expert on plugs but there not bright white and there not black either so looks pretty normall.

[666damned]

ever get the feeling you wish you had never asked......................lol.......

[elnevio]

ever get the feeling you wish you had never asked......................lol.......

Yes, I wish you'd never asked...

[Subaru ETA]

alan , if you want put your car rich and dont cut 15 psi , get out the thermostat . and done ,

wow! why didnt i think of that!

[AlanDITD]

ever get the feeling you wish you had never asked......................lol.......

Better to know i would say, Its true that every car is differnt. The only sure fire way to be 100% your car is safe is to buy monitoring tool. Wideband, and evo scan would be a good start, before messing.

Everyone is quick to say that you can run untill fuel cut etc etc, but know one knows 100% for sure that its is safe 100% of the time.

[Ryan]

I'm no expert on this, but a large plug gap and high boost would probably lead to blow out/misfire I think? I'm not sure how this would lead to high temps.

This is precisely what happened to me when running higher boost on standard (1.1mm) gap plugs. An example of what would happen would be say... snap from 4th to 3rd at 100km/h and it would build.... build and then *pop* and car would lose power. To get around this I'd have to snap it and then roll my foot on the throttle

Have since changed to 0.8mm and new ignition leads which does help quite a lot.

[elnevio]

standard (1.1mm) gap plugs

Regardless of boost levels, 0.8mm is the standard plug gap for the 6A13TT.

1.1mm is however the standard gap for the N/A 6A13.

[AlanDITD]

Ok some figures from the wideband i used today. On my car at standard (or as near to as possible give mods) boost pressure, car went off the scale rich down into the 9's somewhere.

At 13-14psi where i have left it, the car is 11.3-11.5 on full go. Its prefect 14-15 on partial throttle.

Obv that doest tell us anthing about ign timing which is where i think performance is suffering. About to go try evo scan for the 1st time see if i can get some knock readings.

[Ryan]

Regardless of boost levels, 0.8mm is the standard plug gap for the 6A13TT.

1.1mm is however the standard gap for the N/A 6A13.

Clearly I am misinformed.

[vr4-fan]

well , I dont understand HOW he can get 13.6 , with only 11 psi! your car its manual??? my car with 14 psi , only run 14.2 sec stock

[Turbo_Steve]

Hi VR4-fan:

What are the ambient temps when you run?
What is the air-pressure (e.g. how far above sea level are you?)
How are you launching the car?

Maybe do a search on "Drag strip", "launch" or "Santa pod".

I'd suggest you probably need to start a fresh thread.

And sometimes, more boost is NOT the same as more power.
If you're getting detonation, then the car will be pulling timing.
What condition is your transfer case and diff fluid in?
If ambient temps are high, what intercooling are you running?

If you can get your hands on a CO2 fire extinguisher and you're on the factory cooler, and it's really hot where you are, you may find it helps to freeze the intercooler using your fire extinguisher just before you run.

[AlanDITD]

well , I dont understand HOW he can get 13.6 , with only 11 psi! your car its manual??? my car with 14 psi , only run 14.2 sec stock

So its not stock then? Maybe i have more mods, maybe you cant drive. Every car is differnt i dont know. Its pointless even comparing. There different strips, differnt fuel and differnt countries.

There is no comparrison. Maybe you have the fastest Vr4 in the country your from??


Dont get so hung up on times, there noice to have but unless you are racing on the same day as another car then theres no comparrison really.

Its mean to be fun, i think you take all of this far to seriously tbh.

[vr4-fan]

Hi VR4-fan:

What are the ambient temps when you run?
What is the air-pressure (e.g. how far above sea level are you?)
How are you launching the car?

Maybe do a search on "Drag strip", "launch" or "Santa pod".

I'd suggest you probably need to start a fresh thread.

And sometimes, more boost is NOT the same as more power.
If you're getting detonation, then the car will be pulling timing.
What condition is your transfer case and diff fluid in?
If ambient temps are high, what intercooling are you running?

If you can get your hands on a CO2 fire extinguisher and you're on the factory cooler, and it's really hot where you are, you may find it helps to freeze the intercooler using your fire extinguisher just before you run.

88F

28psi air pressure

launching 2200rpm


the problem its the car have detonation i thing the spark its bad , and 1 bar ayc on when I star run ,

[thorpe1983]

my mates vr4 is running 16psi and is running great

[Kelly&Ben]

Ok some figures from the wideband i used today. On my car at standard (or as near to as possible give mods) boost pressure, car went off the scale rich down into the 9's somewhere.

At 13-14psi where i have left it, the car is 11.3-11.5 on full go. Its prefect 14-15 on partial throttle.

Obv that doest tell us anthing about ign timing which is where i think performance is suffering. About to go try evo scan for the 1st time see if i can get some knock readings.

my afr's are pretty similar if i remember right from the rolling road and thats at same(ish) boost

[Subaru ETA]

well , I dont understand HOW he can get 13.6 , with only 11 psi! your car its manual??? my car with 14 psi , only run 14.2 sec stock

everybody knows the only real way to compare is to have the cars, sitting next to each other at the same track. Even then, if you cant drive for **** you are still going to loose even if your car is faster!

[Turbo_Steve]

VR4-Fan, you haven't mentioned what AFRs you're running?