Induction Temperaure - Bad

[Benny]

I'm with you mickq. If the intake temperature was to reach a temperature of such a proportion that it was to blister the paint on the intake plumbing then the car would have to be very close to detonation and losing a great deal of hp. I to think that it's under bonnet temps causing the blistering. Another way to prove this is to go for a spirited drive then stop lift the bonnet and feel the temperature differance between the plumbing before and after the intercooler.

[cuspub]

My apologies with regards to the comments at the opening of this thread.

I was in fact wrong about the modifications as when the manifold was removed (and the photo taken), the car had not been modified. Rather the paint had started to flake off with a stock engine.

In other words, the intake temperatures with the stock combo are high. No question.

[hammer007]

Still a valid point that surely there must be something to be done to reduce the udner the bonnet temps.

I don't mind bonnet vents - they were ok on the EF/EL and if we get past the cosmetic versus function arguments.

Has anyone fitted vents yet ? Are they available ?

[ktford]

Dynosteve has aftermarkets available.

Scotty

[bcl]

I do like Dynosteve’s bonnet, and am seriously tempted, but it’s a bit colder here in Sydney (actually feels like it’s freezing now) than in sunny Qld.

Mickq,

My opinion and observations with regards to a number of your comments, other than the blistering, on which we agree.

And changing the exhaust from the turbo back wont effect boost.

I have 4 dyno graphs from 4 runs each of which have a different exhaust variation, on an otherwise stock vehicle.

I have printouts of the boost for each run.

My stock car shows a slight boost spike to 6lb at 90kph, fairly smoothly coming down to 5lb at 110kph, then to 4.5lb at 128kph, then gradually back up to 5.5 lb at 155kph, then down to 4.5lb at 163kph.

Just because it is electronically controlled does not mean uniform boost or that there will be no boost spikes. You have a mixture of electronics and mechanical ( a la spring) trying to control boost, as well as the natural exhaust pressure on the wastegate when it is closed. It will not be a perfectly controlled boost, but a variation of 1.5 lbs should not be an issue.

With the full exhaust change I’ve done I have a graph that shows consistently 0.5lb extra boost across the whole run. With a partial exhaust change the boost is somewhere in between for the other 2 runs. With the full exhaust the first boost spike hit 5kph earlier. Even an extra 0.5lb boost should result in some extra HP.

Its theoretically possible that the turbo may spool up a little faster due to the freer flowing exhuast gases, but this is not the same as increasing boost.

Faster turbo spool-up IS what brings boost on earlier… that’s exactly what you do want. The faster you hit the peak boost the more likely that you’ll have a boost spike.

I know it’s only low boost, but the initial boost spike did increase.

And not all boost controllers (EBC’s) are made the same.

On the intake side, the exhaust ports are closed when the turbo is shoving air into any given cylinder, so the exhuaust mods are having no effect at all on that side either.

Not sure what you mean, cars do have valve overlap. On non VVT cars, turbo cars have far less overlap than non-turbo cars, on VVT cars possibly almost no overlap at low rpm. At higher rpm on higher boost I’d be amazed if there was no overlap (unless you really want to keep power down). That means that the exhaust valve will still be open at the start of the intake stroke, and close during the intake stroke. Nevertheless less backpressure on the exhaust side should mean better flow. Actually, when we put on the new cat and bigger front exhaust section, the sound jumped over 10db (center muffler already removed), so we new the change had good potential to flow.

Finally, with the factory design the motor looks like a good heater for pre and post intercooled air! Anyone measured it! However, my paint was blistered before any mods.

Brian

[mickq]

My apologies with regards to the comments at the opening of this thread.

I was in fact wrong about the modifications as when the manifold was removed (and the photo taken), the car had not been modified. Rather the paint had started to flake off with a stock engine.

In other words, the intake temperatures with the stock combo are high. No question.

You are missing the point.

The problem is a PAINT problem.

Not an air intake problem.

There is no way that the air intake temperature is high enough to bubble that paint.

The problem is ambient air temperature under the bonnet in combination with the chosen paint type, nothing more.

It has nothing to do with exhuast mods OR air intake temps.

[mickq]

And changing the exhaust from the turbo back wont effect boost.

I have 4 dyno graphs from 4 runs each of which have a different exhaust variation, on an otherwise stock vehicle.

I have printouts of the boost for each run.

My stock car shows a slight boost spike to 6lb at 90kph, fairly smoothly coming down to 5lb at 110kph, then to 4.5lb at 128kph, then gradually back up to 5.5 lb at 155kph, then down to 4.5lb at 163kph.

Just because it is electronically controlled does not mean uniform boost or that there will be no boost spikes. You have a mixture of electronics and mechanical ( a la spring) trying to control boost, as well as the natural exhaust pressure on the wastegate when it is closed. It will not be a perfectly controlled boost, but a variation of 1.5 lbs should not be an issue.

With the full exhaust change I’ve done I have a graph that shows consistently 0.5lb extra boost across the whole run. With a partial exhaust change the boost is somewhere in between for the other 2 runs. With the full exhaust the first boost spike hit 5kph earlier. Even an extra 0.5lb boost should result in some extra HP.

Its theoretically possible that the turbo may spool up a little faster due to the freer flowing exhuast gases, but this is not the same as increasing boost.

Faster turbo spool-up IS what brings boost on earlier… that’s exactly what you do want. The faster you hit the peak boost the more likely that you’ll have a boost spike.

I know it’s only low boost, but the initial boost spike did increase.

And not all boost controllers (EBC’s) are made the same.

On the intake side, the exhaust ports are closed when the turbo is shoving air into any given cylinder, so the exhuaust mods are having no effect at all on that side either.

Not sure what you mean, cars do have valve overlap. On non VVT cars, turbo cars have far less overlap than non-turbo cars, on VVT cars possibly almost no overlap at low rpm. At higher rpm on higher boost I’d be amazed if there was no overlap (unless you really want to keep power down). That means that the exhaust valve will still be open at the start of the intake stroke, and close during the intake stroke. Nevertheless less backpressure on the exhaust side should mean better flow. Actually, when we put on the new cat and bigger front exhaust section, the sound jumped over 10db (center muffler already removed), so we new the change had good potential to flow.

Finally, with the factory design the motor looks like a good heater for pre and post intercooled air! Anyone measured it! However, my paint was blistered before any mods.

Brian

Who said there would be uniform boost? Its rare to see uniform boost on any modern car.

Your figures indicate that the turbo with its wastegate and ECU controller only function within a 8.3% tolerance of intended boost. I disagree. The tolerance is lots less than that.

As I said, Id certainly expect an earlier boost, but an overall and worse still steady increase in boost acorss the rev range? I doubt it.

Mechanical springs may not be as reliable as electronics, but no way a mechanical spring will be equally off across the entire rev and boost range. I would at a minimum expect it to react differently depednign on the situation, for example, is the increase in throttle sudden or gradual.

Were you there, and not only there but carefully watching what they were doing on the computer when they did those runs? Its not at all unusual for dyno runs to be "tweaked" to show the benefit of the money you just spent. You can do it very easily in many ways, including setting up a different ambient temperature. Its not at all uncommon, and if you want 3rd party proof, you can see articles on this if you search the net.

"The faster you hit the peak boost the more likely that you’ll have a boost spike. "

What does that mean? Peak boost is a potential boost spike. Im not sure what you mean by boost spike. Peak boost is peak boost. You cant have peak boost and a boost spike and they not be the same thing.

Freer flowing exhuasts are about nothing more than spooling the turbo up faster if possible: they dont effect boost peaks.

Modern cars have very little valve overlap. Valve overlap equals lower fuel efficiency and also much higher emmissions output. This is because fresh fuel mix containing unburnt fuel will be shoved out the still-open exhaust valve. (The Catalytic converter will only take care of so much). If you read the pollution info on this car, you will quickly realise there is very little overlap.

Less back pressure sometimes means better flow. But it also has a downside. It means less gouging of the cylinder prior to the next intake stroke. So you still have some of last-strokes crap in the cylinder when the new intake occurs. This is why few engines not specifically designed for it work better with no exhuast system. Remember no exhaust system (whether it be straight out of the engine into the air, or a straight through system) is the best example of a free flowing exhuast system that there is. Ive tried everything from normal to free flowing exhuaust through 2 foot straight pipes on a variety of engines.

Removing a muffler may improve flow. But dont for a minute think there is a linear relationship between dB increase and exhaust flow. There isnt. By removing a muffler you do usually increase flow a bit, but much of the extra noise is due to other things the muffler usually does to cancel noise, and that includes reflected noise from the resonator cancelling out the next pulse.

Noise increase does not map directly to increased flow.

[Guest Scootre]

I've just ordered a T and have 10 days to go so have nothing here to look at; what is the bonnet protection like from all this heat we are talking about?

Like are we to expect a nice crazed pattern in the bonnet paint in a couple of years, right over the intercooler?

[NT TURBO]

I've had no intake paint or bonnet issues from heat? I dont really flog the car but its done long periods at high speed up here.

[Guest Scootre]

I've had no intake paint or bonnet issues from heat? I dont really flog the car but its done long periods at high speed up here.

Y'know... I've never had any great urge to visit the NT by road. Until now. My T is on order (9 more sleeps). And all I want to do is hit those glorious NT open roads...

What type of speeds do you cruise at with yours mate?