How throttle body size affects performance on a stock AWP 1.8T engine.
As some of you know we have been looking into purchasing an engine dynamometer for some time to not only test X , Y & Z products but to also see where improvements could be made. Unfortunately with the way the economy was at the start of 2009 , alot of testing had to be put on hold until recently. Unitronic Chipped as the 1.8T forum sponsor offered the use of there engine dyno for our testing to truly show what can be done with these motors so I will do my best to gather the components, extract the data and present it for the VAG community as a whole.
Before I begin I want to thank Unitronic Chipped (Mike Z. & Mike S.) for allowing me to use their DTS Engine Dynamo-meter and SEM Motorsport team (Marco & Donato) for providing the intake manifolds to conduct this test.
Everyone involved was nothing but professional and courteous.In the future I will be providing alot more data and accurate dyno's with their help.
This is where all the magic happens:
When I arrived at Unitronic Chipped HQ'ers in Laval Quebec, Mike Z.had already done a couple of pulls with the 80mm Dodge Hemi throttle body and was using this as the base for our test.The good thing about doing these tests on an engine dynamometer is that swapping throttle bodies took minutes and simple tweaking of the maps by Mike allowed maximum gains to be had with each pull for each TB.
These tests were conducted under a "what you see is what you get" mindset. Even we were surprised by some of the results and I hope you are too... :D
Onto the show:
Originally Posted by Unitronic 1.8T Engine Spec
All throttle bodies were tested doing 2 pulls at 1 bar and 1.5 bar respectively. 1 bar being wastegate pressure of 14.7psi (was actually 17psi due to the SEM manifold) and 1.5bar being controlled with a greddy unit (22psi).Below is a recording of peak power made in each dyno run using the SEM small port manifold & the respective throttle body. For reference we have included what the same engine made utilizing a stock AWP manifold and throttle body.
For this test the following nomenclature represents each throttle body.
80mm = Dodge Hemi 5.7L
75mm = Audi B5 RS4 2.7L - TT
70mm = Mercedes-Benz C320 – 3.2L
65mm = Audi B5 S4 – 2.7L / VW Golf & Jetta 2.8 24V VR6
60mm = Volkswagen Passat B5 1.8T
Cross Section Area’s of the throttle plates / Percentage increase % over stock 60mm unit
80mm = 5026 mm2 / +43.8%
75mm = 4417 mm2 / +35.9%
70mm = 3848 mm2 / +26.5%
65mm = 3318 mm2 / +14.7%
60mm = 2827 mm2 / +0%
TESTS:
HORSEPOWER / correctedhp
BOOST : Wastegate pressure - 17PSI
80mm: = 388.9 hp @ 7300 rpm
75mm: = 390 hp @ ?
70mm: = 383 hp @ 7200 rpm
65mm: = 378 hp @ 6500 rpm
60mm: = 374 hp @ 6700 rpm
BOOST - 22SI
80mm: = 451 @ 6700 rpm
75mm: = 447 hp @ ?
70mm: = 447 hp @ 6700 rpm
65mm: = 430 hp @ 6800 rpm
60mm: = 439 hp @ 6800 rpm
STOCK AWP Manifold + 60mm: = 421 hp @ 7100 rpm
TORQUE / lb-ft
BOOST : Wastegate pressure - 17PSI
80mm: = 322 lb-ft @ 5600 rpm
75mm: = 333 lb-ft @ ?
70mm: = 318 lb-ft @ 5600 rpm
65mm: = 320 lb-ft @ 5800 rpm
60mm: = 312 lb-ft @ 5700 rpm
BOOST - 22SI
80mm: = 380 lb-ft @ 5500 rpm
75mm: = 382 lb-ft @ ?
70mm: = 374 lb-ft @ 5600 rpm
65mm: = 369 lb-ft @ 5600 rpm
60mm: = 371 lb-ft @ 5600 rpm
STOCK AWP Manifold + 60mm: = 365 lb-ft @ 5100 rpm
NOTES:
80mm:
As expected on the 80mm unit, the most power was developed, great throttle body for an all out drag car.
75mm:
RS4 throttle body results were very surprising, the 75mm unit made more power at WG pressure, had better idle and better response than the 80mm unit.
70mm:
This unit relieved the chope point noted in smaller throttle bodies.
Power gains were also noted above wastegate pressure noted.
65mm:
Also we noted that a choke point was created at 7000 rpm’s. Engine response became sluggish and timing was pulled to compensate for choke point created due to too small a throttle plate.
60mm:
This is the throttle body that I believe a lot of big turbo users need to keep an eye on. What could be timing being pulled due to a “bad tune” could be associated with too small a throttle body. At 6900 rpm’s it was literally like hitting a brick wall. Engine started to choke and detonation was being detected.
CONCLUSIONS:
1. If you are running a turbocharger rated for 450hp or more , then it is highly recommended to have a throttle body greater than 65mm.We expected the results to be amplified had the motor been built with a larger ported cylinder head (AEB/AJL/ADR).
2. For 99.99% of the 1.8T users, a 70mm / 75mm DBW throttle body will more than suite your needs.
3. If you are a user with a home brew or custom intake manifold with a larger plenum and you are running a stock 60mm throttle body then you are actually hurting performance rather than helping and it is recommended you get an upgrade. Same applies for users running an SEM motorsport intake manifold and a 60mm OEM throttle body.
4. Throttle body adaptations can only get you so far. Every single one of these throttle bodies needed the map to be tweaked. In no situation was it a simple “plug and go” . Some might get away with lemiwinks whereas others will have to look into an entire motronic retune.
p.s. I am waiting on Lavi@Unitronic to provide the raw data so I can export to an excel file to give you a comparison all on 1 dyno graph.
For all the images of the dyno day click here.
If you are interested in Unitronic Chipped Services click the banner below:
Thanks,
Issam
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