Intake options
Discussion
My air intake is currently standard other than a BMC free flow panel filter. I've got a full exhaust system on it and I'm looking at one of two options.
1. Install the over the radiator cool air intake
2. Fit the bigger airbox with the pod filter
Also wondering about the pipe to the throttle body and whether a bigger one will help.
Any feedback about what you guys have done and the results you got is appreciated.
1. Install the over the radiator cool air intake
2. Fit the bigger airbox with the pod filter
Also wondering about the pipe to the throttle body and whether a bigger one will help.
Any feedback about what you guys have done and the results you got is appreciated.
an otrcai will cost around 300 quid from US or Oz and require a mafless remap and is generally accepted as being the method of choice in both of the above, though there is the question of heatsoak from sitting on top of the radiator which puts some people off them. There is a cheap and cheerful mod that can be done - the 2nd hole mod for the airbox which makes a big difference to the airflow reaching the filter. Its more of a diy thing though. Search the forums on here and the US GTO forums for instructions on how to do it - large circular saw bit for drill and 3" of drain pipe usually all that is required. As for a bigger pipe to the throttle body - if you've a cv8 then you do get some small benefit from fitting a smoothed pipe as the stock item isnt great - you're looking at around 80 quid for a replacement, options included coloured, polished aluminium and carbon fibre. Also depending on model a larger throttle body can help but its expensive for the potential gains when fitted on its own. Recommend a remap with any mods though.
Even a basic cursory glance in the ls1.com.au forums will show you that if you are even vaguely interested in NA power you should have an OTRCAI. I doubt you will find anyone with any semblance of power naturally aspirated with anything other than the otrcai.
I cant say Ive seen anyone saying that the otrcai heaksoak loses it power over the standard type. But Id like to see the evidence.
For info on why you want to go otrcai take a look here with evidence of the power increases.
http://www.chipmaster.com.au/ProjectVE_1.html
I cant say Ive seen anyone saying that the otrcai heaksoak loses it power over the standard type. But Id like to see the evidence.
For info on why you want to go otrcai take a look here with evidence of the power increases.
http://www.chipmaster.com.au/ProjectVE_1.html
I just read the project Monaro article on the chipmaster website. Really interesting as it was a good narative summary of the process we would probably all naturally follow when modifying the 'ro.
Basically they took a standard 5.7 Monaro which had 168.7 RWP and ran 14.51@96.9mph.
They did the exhaust, re-map, and added a 3.77 diff and a K&N filter. This produced 221.3kW and ran 13.54@105.5mph.
It follows on to say...
"Testing both at the drag strip and on the dyno showed that we had a intake problem , both in terms of heat buildup and intake restrictions.
Next it was time to look at the MAF pipe as it appeared to have be a restriction in cross sectional; area , a Convoluted pipe and a smooth bore 4" custom pipe and a new plastic 4" moulded pipe was trialed. Power gains were found with all of the intake pipes but we elected to stick with the Moulded 4" pipe as much for appearance sake as the added power increase .We will use this same intake pipe for all our testing .
The tune was then optimized again to suit this new pipe as our baseline , power had at this point picked up 226.9kw with the std air box modified and the K&N air filter installed.
Different air boxes were now tested , with our std Monaro modified air box used as the baseline , and a modified HSV air box system , power at this point was unchanged but the HSV box produced a slightly lower intake temp consistently due to it being better sealed around the headlamp than the std Monaro CAI which draws air from around the top near the radiator as well resulting in hot radiator air being ingested. We also tested a popular widemouth CAI but found large horsepower losses above 4500rpm due to a restriction over the radiator cowling so we abandoned any further testing."
It goes on from there to have a MAFless tune added, and so on... but that isn't what you asked about
Basically they took a standard 5.7 Monaro which had 168.7 RWP and ran 14.51@96.9mph.
They did the exhaust, re-map, and added a 3.77 diff and a K&N filter. This produced 221.3kW and ran 13.54@105.5mph.
It follows on to say...
"Testing both at the drag strip and on the dyno showed that we had a intake problem , both in terms of heat buildup and intake restrictions.
Next it was time to look at the MAF pipe as it appeared to have be a restriction in cross sectional; area , a Convoluted pipe and a smooth bore 4" custom pipe and a new plastic 4" moulded pipe was trialed. Power gains were found with all of the intake pipes but we elected to stick with the Moulded 4" pipe as much for appearance sake as the added power increase .We will use this same intake pipe for all our testing .
The tune was then optimized again to suit this new pipe as our baseline , power had at this point picked up 226.9kw with the std air box modified and the K&N air filter installed.
Different air boxes were now tested , with our std Monaro modified air box used as the baseline , and a modified HSV air box system , power at this point was unchanged but the HSV box produced a slightly lower intake temp consistently due to it being better sealed around the headlamp than the std Monaro CAI which draws air from around the top near the radiator as well resulting in hot radiator air being ingested. We also tested a popular widemouth CAI but found large horsepower losses above 4500rpm due to a restriction over the radiator cowling so we abandoned any further testing."
It goes on from there to have a MAFless tune added, and so on... but that isn't what you asked about
One thing to be careful of with larger throttle bodies that I've found on other cars.
What you find is that for a given throttle pedal position a larger amount of air is allowed to pass into the engine. This may sound good but a side effect is that you lose the linear nature of the throttle pedal.
For example, assume when standard a 1 - 1 mapping between throttle pedal and throttle body position.
So:
10% throttle pedal = 10% throttle body
...
50% throttle pedal = 50% throttle body
...
100% throttle pedal = 100% throttle body
Now as more air is flowing into the engine and assuming the engine map takes account of this (most do within a certain tolerance) then the effect is exactly the same as pushing the pedal open more when standard.
So:
10% throttle pedal = 11% throttle body
20% throttle pedal = 25% throttle body
30% throttle pedal = 37% throttle body
40% throttle pedal = 48% throttle body
50% throttle pedal = 59% throttle body
60% throttle pedal = 70% throttle body
70% throttle pedal = 81% throttle body
80% throttle pedal = 90% throttle body
90% throttle pedal = 95% throttle body
100% throttle pedal = 100% throttle body
this is what cars with "sport" mode do with the electronic throttle to give the effect of a more responsive throttle. The downsides is that can make the car harder to control at low speed and make it seem to kangaroo. Some people like it I personally hated it as it made things tricky on the limit when trying to balance the car on the throttle.
I'm sure if done properly the map can be changed to make it work linearly again.
What you find is that for a given throttle pedal position a larger amount of air is allowed to pass into the engine. This may sound good but a side effect is that you lose the linear nature of the throttle pedal.
For example, assume when standard a 1 - 1 mapping between throttle pedal and throttle body position.
So:
10% throttle pedal = 10% throttle body
...
50% throttle pedal = 50% throttle body
...
100% throttle pedal = 100% throttle body
Now as more air is flowing into the engine and assuming the engine map takes account of this (most do within a certain tolerance) then the effect is exactly the same as pushing the pedal open more when standard.
So:
10% throttle pedal = 11% throttle body
20% throttle pedal = 25% throttle body
30% throttle pedal = 37% throttle body
40% throttle pedal = 48% throttle body
50% throttle pedal = 59% throttle body
60% throttle pedal = 70% throttle body
70% throttle pedal = 81% throttle body
80% throttle pedal = 90% throttle body
90% throttle pedal = 95% throttle body
100% throttle pedal = 100% throttle body
this is what cars with "sport" mode do with the electronic throttle to give the effect of a more responsive throttle. The downsides is that can make the car harder to control at low speed and make it seem to kangaroo. Some people like it I personally hated it as it made things tricky on the limit when trying to balance the car on the throttle.
I'm sure if done properly the map can be changed to make it work linearly again.
Thats very true Mr Green, however the ECU has ability to tune that especially ETC and also cable ones.
I went from 75mm to 90mm and had to reduce whats called throttle follower because as mentioned you get a pretty hard launch unless you wind back airflow at low openings.
If you just swap and dont tune, then I totally agree you may well end up with a lurchy non linear vehicle
I went from 75mm to 90mm and had to reduce whats called throttle follower because as mentioned you get a pretty hard launch unless you wind back airflow at low openings.
If you just swap and dont tune, then I totally agree you may well end up with a lurchy non linear vehicle
Gassing Station | HSV & Monaro | Top of Page | What's New | My Stuff