In our last few Beyond Stock updates, we have been focussing on the Civic. In particular, we did a special look to establish reference figures for stock Civic SiRs, both automatic and manual. To continue this thread, I decided to look at stock DC Integras, i.e. the 1993-current generation. In this article, I will look at both the manual and the automatic Integra SiR (or Si-VTEC) together and will attempt to establish a reference power level for them.
Introduced in April 1993 to replace the very successful DA-series Integra, the DC-generation Integra saw the significant introduction of the B18C engine. The 2-door coupe was coded DC2 while the 4-door sedan DB8. The larger displacement B18C generated an additional 10ps - 15ps but more importantly made use of VTEC and a variable volume intake manifold (dubbed VVIS) to give an extremely flat torque curve, giving not only high horsepower but very preppy midrange as well.
The B18C displaces 1797cc, using the same bore as the B16A with an extended stroke. The DOHC VTEC valve train gave the manual version 180ps max power at 7600rpm with max torque of 17.8kgm at 6200rpm. Red-line is at 8000rpm. The automatic version generates a relatively high max power of 170ps at 7200rpm, only 10ps down from the manual. Max torque for the auto is the same 17.8kgm but at a lower 6000rpm. Redline for the auto is around 7600rpm.
Having established to a very good approxmation that total losses (transmission + accessories) for Hondas is 15% for manual and 30% for auto, we can thus derive the expected theoretical dynojet figures. For manual DC2 or DB8 we will thus expect around 153ps while for automatic DC2 or DB8 we should be expecting around 119ps, both for results on a Dynojet.
The owner of the DC2 in this article, Mike, upgraded from his VTEC-Civic in 1999. Enlisting the help of his friends, he was fortunate to have a number of DC2s and DB8s to choose from. In the end, the extremely good condition of a pearl black DC2 caught his heart and he decided to purchase it. His car forms the masthead for this article.
After the obligatory round of extensive service, Mike decided to complement it with a package designed to ensure that the engine is in peak health. This package consists of cleaning the injectors (on a injector cleaning machine) plus a HKS AFR to make sure the engine's air-fuel mixture is optimized for the local atmospheric conditions. An added advantage to the AFR package is the dyno-tuning provided will also allow the base distributor timing to be optimized.
As discussed above, the theoretical dyno'ed power for a manual DC2 is derived to be around 153ps at the wheels. The dynojet chart reproduced on the right however shows the first base-run to be at 148ps. However, this is only the base-run, with work still to be done flowing the injectors as well as fine-tuning the air-fuel ratio using the HKS AFR. Without both of these, the air-fuel ratio is not optimum, so the 148ps delivered is actually below par for the engine.
With the injectors cleaned and checked to be flowing at 100% efficiency, the re-dyno now delivered almost 151ps at the wheels, a 3ps gain. The injector cleaning process starts with an initial calibration check and the injectors were found to be flowing at quite a bit below the spec rate. Since PGM-Fi meters amount of fuel flow into the combustion chamber by regulating the injector opening duration, so the partially blocked injectors were causing a lean air-fuel ratio at the engine. Cleaning the injectors consists of immersing them into an ultrasound bath, using a special injector cleaning solution. Ultrasound works like many tiny hammers chiselling away at the blockages at the injector nozzle and the re-check done after the ultrasound cycle was completed showed that all the injectors now being balanced and flowing at 100% or very close to 100% efficiency. Usually, the fuel-filter will also be changed as well. Performing the injector cleaning package brings the engine's operating air-fuel ratio right back to near optimum, directly giving the 3ps power gain. Clearly seen from the dyno chart is the consistent gain across the whole dyno rpm range, confirming the benefits of having the injectors cleaned.
With the injectors now working at proper efficiency, the AFR is now installed and used to further calibrate the engine's air-fuel ratio to the local atmospheric conditions. As described in many previous articles, this consists of properly setting the AFR on the dyno as well as setting the base ignition timing via the distributor. This tuning showed gains mostly in the high-rpm range; gains started only around 5000rpm, a bit after VTEC has activated the wild-cams with significant gains obtained after 6000rpm, when VVIS opens the secondary intake runners. Final dyno'ed power was almost 153ps at the wheels, spot-on the theoretical calculated power based on 15% over the spec 180ps at the engine !!
Based on this particular case, we should be confident therefore to set our reference value for stock manual B18Cs to be 153ps at the wheels on a Dynojet machine.
The second Integra I am looking at in this article is an automatic DB8. Khu bought this in very good condition as a 6 year old un-registered example, during the bottom of the currency crisis that hit Malaysia a few years ago. Everyone have since envied his extremely good luck since the price he paid at that time is actually lower than that being asked for same-aged pre-owned used examples being sold now !
Khu has always maintained to me that he intends to keep his car "stock". But I've always felt that he has a rather "flexible" definition of stock. At the time Khu sent his car for dyno, he has a K&N cone filter replacing the stock filter. B18C's stock filters are already conical in design and the K&N could be used as a direct drop-in replacement, fitting nicely into the stock air-filter box ! He also replaced his rear muffler box with one from a stock 96-Spec Integra Type-R. Finally being a reader of TOVA, he fully believes in injector cleaning and AFR benefits, so his injectors were cleaned. He also purchased a used AFR for the car. Quite a handful indeed for a "stock" DB8 !
Khu's Dynojet session came about when he was able to share a block of dyno-time with some members of our Honda club. His intention was to properly set the AFR for optimum air-fuel ratio for the local atmospheric conditions, as well as to set the base ignition timing via the distributor.
Khu's dyno-chart is reproduced on the left. The base line run showed around 116ps at the wheels, with a reasonably smooth power curve, except for a dip between 6000rpm to about 6700rpm. This base-line run is for already cleaned injectors, with just the AFR and base ignition timing to be set. Adjusting the AFR plus setting the base timing allowed his DB8 to finally dyno at almost 119ps at the wheels, once again spot-on the theoretical figure !
In Khu's DB8 however, very significant gains were obtained all across the rpm range, with especially good gains in the low and mid rpms. Being the sensible automatic driver, Khu was very impressed and happy with the gains, since almost 8ps gains were recorded in the low rpm range of between 2500 to 4000rpm. This gives the car is much more spirited character for in-town drives and especially beneficial for an automatic transmission.
In Khu's case however, we need to bear in mind that the air-filter is an upgraded freer-flowing K&N unit while the muffler (exhaust back-box) is the lesser restriction stock Integra Type-R one. Nevertheless, both the items are not expected to produce great power gains, so taking into account the power dip between 6000 - 6700rpm (which could have taken the max power to 120ps and beyond), Khu's DB8 do give us confidence to peg the power of a stock automatic B18C to 119ps on a Dynojet machine.
I am very fortunate in being able to establish a working relationship with the reference Integra site The Integra Dyno Center. Our agreement is one where I am able to quote or use selected material (with permission) from the site to complement and enhance my articles here, while at the same time those article will also be highlighted at the 'Dyno Center' as well. This is a very good working relationship and as a direct result of the site's generousity, I am in the unique position of being able to use material from the site to cross-check the materials I have in this article.
Although the site concentrated on U.S. model Integra GS-Rs, there was a record for a JDM Integra SiR-G that was imported into Jamaica. The owner reported a stock power run of 149ps at the wheels for his baseline value. This run was recorded with the car exactly as it was received from Japan and would thus corresponds directly with Mike's original (first) run of 148ps. As can be seen, the two results corresponds to each other very well and this gives us full confidence that Mike's results (as well as that reported in the Integra Dyno Center) are fully representative for a typical DC2.
Based on the results examined in this article, we can thus feel confident in establishing the following base-line reference :
These reference values would prove invaluable to the enthusiasts for many uses, especially when evaluating the power gain of a mod when the baseline power is not available.
WongKN
March 24 2001
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