Is There Any Benefit To This Turbo Set Up?

[mad082]

the cost will be somewhat less than a standard turbo upgrade as the cost of getting the exhaust modified will be much less than getting a custom manifold made (since not every car has a factory turbo manifold that will fit). no need to run an intercooler, so that more than covers the extra cost of piping.

[Peter89]

the cost will be somewhat less than a standard turbo upgrade as the cost of getting the exhaust modified will be much less than getting a custom manifold made (since not every car has a factory turbo manifold that will fit). no need to run an intercooler, so that more than covers the extra cost of piping.

exhaust manifold only slightly increase the price considering all the other parts.

as if no intercooler that would increase lag and limit the amount of boost you could run.

[mad082]

how would an intercooler increase lag? an intercooler increases lag for 1 reasons, 1: there is a much bigger space to be filled than a bit of piping, 2: it adds a bit of restriction to the system.

as for limiting the amount of boost that can be run, because the piping is longer there is less need for a cooler as the air is cooled a bit as it travels along the piping. also these turbo setups are generally installed on NA cars, so the compression engine is going to be more limiting in how much boost you can run than the lack of an intercooler. that is also why i made the point about them not being a hardcore turbo upgrade. anyone who bolts a turbo to a stock NA motor isn't really going for a hardcore setup. if they were they would decompress the head to allow them to run more boost. look at the turbo kits you can buy for a lot of NA engines. they are generally only designed to run 5 or 6psi. you never see them designed to run 15 or 18psi. they are purely designed to run within the limits of the stock engine with very minimal upgrades. some don't even really change the ecu and simply add in another injector to add a bit more fuel.

[Peter89]

longer piping wouldn't see huge drops in intake temps kinda the reason for intercoolers. i highly doubt 1m or even 5metres of piping would see a strong reduction in intake temps at 6psi and especially if running anything like 1 bar compared to even a small intercooler.

maybe lag was the wrong word but performance gain for the boost levels used. sure you could run 6psi but even with a small intercooler the slight drop in response for vastly cooler intake temps which in term results in more power is worth it. so in the end these turbos aren't as efficient because they aren't as close to the exhaust manifold, wont run intercoolers so intake temps will be higher and will be limited to low boost levels. practically all power gains would be minimal at best compared to a standard turbo upgrade.

might as well bolt on a small super charger instead.

[Galois]

Just wondering, how much would say rain water affect the fuel maps? So, most of coastal aus, esp south, can have a 20oC swing in temp (from a hot day to a thunderstorm or whatevs). Add water and some speed and the cooling rate of an intercooler or rear turbo and suddenly intake temps are 20-50oC cooler (rough numbers, don't really want to do the calcs).

So the extra cooling increases air density which changed the air-fuel ratio, possibly significantly. How is that countered? Is that what a safe tune implies, that extra lee-way?

Cheers

[mad082]

depends on the car. different cars solve this in different ways. (this is just my understanding of it, so don't take it as gospel) in the case of the skylines and a lot of other cars, they use a heated element in the afm to work out airflow. as the air passes the filament it cooles it. the more it cools it the higher the voltage it sends to ecu and the more fuel it puts in. cooler, more dense air will result in a higher voltage. hotter, less dense air will result in less voltage.

cars that use a map sensor standard will often have an intake air temp probe so that they can then take into account the different air densities.

as for a "safe" tune, that generally refers to how close to the limit the tune is. if they are running at bang on 12:1 or 12.5: AFR and have the timing set to just before it pings then it isn't as safe as a tune at 11.8:1 AFR and the timing backed off a bit. it won't make as much power as the leaner, more agressive tune, but should you have an issue with the injectors starting to not perform as well then there is more headway before damage starts being done. realistically you don't get much safer than the stock tune. they run way more fuel than they need to and pretty low timing. you can have some reasonably big fuel supply issues before things start to get damaged.

[Peter89]

depends on the car. different cars solve this in different ways. (this is just my understanding of it, so don't take it as gospel) in the case of the skylines and a lot of other cars, they use a heated element in the afm to work out airflow. as the air passes the filament it cooles it. the more it cools it the higher the voltage it sends to ecu and the more fuel it puts in. cooler, more dense air will result in a higher voltage. hotter, less dense air will result in less voltage.

cars that use a map sensor standard will often have an intake air temp probe so that they can then take into account the different air densities.

as for a "safe" tune, that generally refers to how close to the limit the tune is. if they are running at bang on 12:1 or 12.5: AFR and have the timing set to just before it pings then it isn't as safe as a tune at 11.8:1 AFR and the timing backed off a bit. it won't make as much power as the leaner, more agressive tune, but should you have an issue with the injectors starting to not perform as well then there is more headway before damage starts being done. realistically you don't get much safer than the stock tune. they run way more fuel than they need to and pretty low timing. you can have some reasonably big fuel supply issues before things start to get damaged.

how does a MFS response to changes in air pressure? example, the bottom of the mountain is 20c with 14.7psi atmospheric pressure and at the top it's 5c with 9psi atmospheric pressure. while the air is cooler, resulting in a cooler filament overall there is less air drawn into the engine? or does the air not cool the filament as quickly because of the different pressure and result in a different reading? thus less fuel?

[JWindsor]

that thing is insane, seen something like that around here

[mad082]

how does a MFS response to changes in air pressure? example, the bottom of the mountain is 20c with 14.7psi atmospheric pressure and at the top it's 5c with 9psi atmospheric pressure. while the air is cooler, resulting in a cooler filament overall there is less air drawn into the engine? or does the air not cool the filament as quickly because of the different pressure and result in a different reading? thus less fuel?

that would be one epicly high mountain to drop 15 degrees and get down to 9psi pressure. you are talking roughly 13,000 feet, (so nearly twice the height of Mount Kosciuszko, and about as high as mt fuji).

as for how they would deal with that, i don't know. i don't know enough about cooling properties at different air densities. but i think that the fact that very few people drive at extreme heights, most car manufacturers wouldn't put that much time into working it out.

[Galois]

Thanks for the answer Marc, that explains it. I had no idea there was a temp sensor in there, esp a heated filament, that's a genuinely good idea.

how does a MFS response to changes in air pressure? example, the bottom of the mountain is 20c with 14.7psi atmospheric pressure and at the top it's 5c with 9psi atmospheric pressure. while the air is cooler, resulting in a cooler filament overall there is less air drawn into the engine? or does the air not cool the filament as quickly because of the different pressure and result in a different reading? thus less fuel?

Lower air pressure means less heat transfer between filament and air, which means it'll think the air is warmer and make it run safer. I don't really want to do the calcs to make sure, but there's a high possibility that the lower cooling effect of low pressure air ends up countering the lower mass flowrate of the low pressure air.

9psi at the top of a mountain? That's an insane drop! It's like half way up everest!

[Peter89]

Thanks for the answer Marc, that explains it. I had no idea there was a temp sensor in there, esp a heated filament, that's a genuinely good idea.

Lower air pressure means less heat transfer between filament and air, which means it'll think the air is warmer and make it run safer. I don't really want to do the calcs to make sure, but there's a high possibility that the lower cooling effect of low pressure air ends up countering the lower mass flowrate of the low pressure air.

9psi at the top of a mountain? That's an insane drop! It's like half way up everest!

maybe 9psi was a little extreme however after doing some calcs. atmospheric pressure is 12.9psi at 1000metres above sea level which isn't that high.

oh well, i guess it doesn't matter.

[VB-]

MAF is Mass Air Flow, it gives no fark for pressure or temperature, it measures mass, and this is what the appropriate amount of fuel needs to be added to. when people talk about air fuel ratio, its actually measured in parts by weight (i think lol), ie: mass

Galois, its not a heat sensor as such. basic way to explain it, there is a 'hotwire' through the AFM, this is basically your signal/output wire to the ECU. with no airflow, its hot and has alot of resistance (small output), as you mash it, more air is drawn over the wire which cools it, which reduces resistance (more output). this is why they work so well, you can be going flat out, running big boost, but if its really hot air (less dense, requiring less fuel) it wont cool the wire much. hot wire = ECU adding less fuel

Edited November 13, 2010 by VB-

[mad082]

MAF is Mass Air Flow, it gives no fark for pressure or temperature, it measures mass, and this is what the appropriate amount of fuel needs to be added to. when people talk about air fuel ratio, its actually measured in parts by weight (i think lol), ie: mass

Galois, its not a heat sensor as such. basic way to explain it, there is a 'hotwire' through the AFM, this is basically your signal/output wire to the ECU. with no airflow, its hot and has alot of resistance (small output), as you mash it, more air is drawn over the wire which cools it, which reduces resistance (more output). this is why they work so well, you can be going flat out, running big boost, but if its really hot air (less dense, requiring less fuel) it wont cool the wire much. hot wire = ECU adding less fuel

that is pretty much what i said above

[Birds]

I remember a Top Gear where they drove cars to the top of a super high mountain and they ran like absolute shit...pretty sure they were old cars though, and it wasn't so much the AFM issues but a lack of oxygen altogether.

[mad082]

exactly. they (jeremy, james and richard) were all having problems breathing, etc. the cars were very much down on power because of the fact that the density of the air was such that the combustion happening inside the engine was extremely weak.

[Galois]

Loved that episode, always wondered though, did hamond really accidentally drop his car down that hill? Or was it set up because he didn't want to do something so stupid after almost losing his life a few years back?

[mad082]

would've been setup purely for entertainment purposes. not because he didn't want to do it or anything like that. purely to be funny.

[paulr33]

a lot of haters in here i see

i think the idea is great if you have an N/A car and want to turbocharge it and have no room etc to fit in the normal method

is it better than N/A Yes? Is it better than doing it properly in the engine bay? No. but if you have no choice, then it is suitable

observations from the video its only 5psi but twin turbonetics, such a waste for an expensive setup!!!!

i dont really like the spool up noise, i prefer my GTST turbo spool up noise from the engine bay to be honest

when you do the rear turbo install there has to be more lag and you can see from his boost guage it takes a while to wind up

sure its twins so you would expect that, but even from that STS thread in the FI seciton, you can see on his guage, there is noticable lag

i think when most people think of the rear turbo setups they expect 5 seconds lag

whereas on an engine bay related setup its usually instant spool up

i think in reality the rear turbo setup would be sub 1500ms lag

and in the engine bay setup it would be sub 500ms lag

i say time when you open the thorttle full to time the turbo charger starts adding positive boost pressure

so i dont think it's as bad as eveyone believes

[Sarumatix]

Another thing I notice, the comment that the intercooler has a large volume of air space to 'fill up'. If you have a decent IC surely the pressure drop should be very minimal. It may have slightly more volume than the piping but hardly enough to really affect lag much. I wouldn't be surprised if a lot of ICs have less volume than the pipework they are attached to and that it's more about the increased friction in the air flow.

[W0rp3D]

Another thing I notice, the comment that the intercooler has a large volume of air space to 'fill up'. If you have a decent IC surely the pressure drop should be very minimal. It may have slightly more volume than the piping but hardly enough to really affect lag much. I wouldn't be surprised if a lot of ICs have less volume than the pipework they are attached to and that it's more about the increased friction in the air flow.

Which is a mute point because if you use this type of set up in the way its meant for (a power boost) you shouldnt even need one, the problem is a lot of people cant seem to grasp the fact that this set up is just a power booster, its not for some one wanting any sort of race car.

Edited November 16, 2010 by W0rp3D