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2.0L Duratec Rebuild


JohnCh
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I've heard that's a good strategy to broaden the torque curve. Did you find that cylinder mixtures were acceptable given you were tuning for the average between longer and shorter runners?

 

Thanks,

John

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We were able to tune individual cylinders by a global %, but it was not a huge amount. If you're not running super lean it should work fine. Initial tests were done with no individual cylinder tuning at the track, then fine tuned on the dyno.

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Good to know, thanks. If the dyno shows there are big gains with this engine by running a variable intake, I plan to take a shot at making one. I picked up the variable intake system from a Yamaha R1 a few years ago for inspiration and when Emerald made my replacement engine loom, I had them include wiring for the native VTEC switch functionality in their ECU. Whether I can get everything to work well and fit within available space is a open -- and very large -- question. The video below shows the system in action. Relatively primitive, but so is the rest of my car :)

 

lr82d.jpg

 

 

-John

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The floods finally receded which enabled me to drop off the rod bearings at the machine shop yesterday. If the standard size prove correct, and there are no other issues (I know, I know…), the short block should be back home by the end of next week.

 

Since people like photos and a photo of a box of bearings is kind of boring, here are a couple of photos of the flooding across the valley between my house and the rest of civilization that delayed the trip. Multiple road closures meant nasty traffic along the one main road that was still open at the north end of town. Thankfully things are back to normal. For now.

 

flooding 0220.jpg

 

flooding 2 0220.jpg

 

-John

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John, when I was putting the Stalker back together, I needed to have the rear end rebuilt and set up. At that time (due to heavy rain associated with a hurricane) the trip to the repair facility required a two-hour trek through the woods from south AR to Shreveport, LA (I-20 was shut down due to flooding). But me, being bound and determined to get my rear end rebuilt, picked and guessed my way down. I ran across one section of flooded road and, well, tested the waters. I considered the mission successful once I was back home....same day.

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Shane, it sounds like your cars have more ground clearance than mine :)

 

I just heard from the machine shop. There is too much clearance with the standard thickness rod bearings, which is the opposite problem we had with the main bearings. New, one size thicker bearings were just ordered and this time they agreed to make an exception and ship directly to the shop.

 

-John

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Same head as before: 2.0L Duratec head with the exhaust tumble removed, some port clean up, and this time he reprofiled the backside of the valves. It may not flow quite as much as a later 2.3L head or the high port head that was available in some non-US markets, but it should flow more than enough for my target of 225-230hp.

 

-John

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The 2.5L head flows better but the ports are different and would require new throttle bodies and header to mate up. Given my current head is more than capable of meeting my power target, and I already have 45mm direct-to-head throttle bodies and a custom header, what would I gain replacing those and using the 2.5L head?

 

Thanks,

John

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I Build a lot of these 2.0 , 2.3 , 2.5 , I have a 2.0 with 2.5 head SCCA legal 11.1 compression , stock2.5 intake manifold , stock Focus TB ( killing us ) no port work , stock valves , crower stg3 cams making 205 whp

 

With ITB like you have if you hit the 220 whp mark with the 2.0 head the 2.5 head would add 10-15 whp to that maybe more because of the higher flowing ITB , where the header bolts to the 2.5 head is the same as the 2.0 so you wouldnt need to change the header , the intake is MUCH bigger and would need addressing

 

Tom

 

Tom

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Thanks Tom, is that 10-15hp increase compared to a stock 2.0L, stock 2.3L, or a ported head? How does it affect the shape of the torque curve? Is it all at the top end or does the revised shape have a meaningful increase at low-mid rpm?

 

-John

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Looking at Jenvey's site, the TBs for the 2.5L are available in 48mm or 50mm whereas they make them from 40mm-50mm for the 2.0L & 2.3L heads either under their brand or partners like Raceline. I intentionally went for the 45mm vs larger when building the original engine 16 years ago as I was advised based on extensive dyno testing, the 45mm is best under 250hp as it will flow to that level and keeps port velocity up to help at low rpm, particularly important when you are doing a 2.0L rather than a 2.3L. The 2.5L sounds like a great option for someone looking for big power or doing a clean sheet build who wants to maintain significant headroom, but I think it's overkill for my needs, particularly given my starting point.

 

Thanks,

John

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The adjustable airhorns from Emerald arrived. Given they slide into the TB, they have a narrower throat than the standard 90mm airhorns (43mm vs. 45mm). They also don't have a flared bell mouth which in theory should further impact airflow. The torque curve comparison when they are set at 90mm should be interesting. One thing I didn't realize is that the adjustment range stated on Emerald's site doesn't apply to my Jenveys without surgery. They should adjust down to 60mm, but at anything less than 77mm they foul the butterfly. Here are comparisons at 77mm, 130mm and looking down the throats.

 

Emerald short.jpg

 

Emerald long.jpg

 

Emerald down.jpg

 

-John

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It seems to me that this is an ideal project for 3D printing. I have a decent 3D printer that can print nylon, and ABS, both of which have enough heat resistance to work. I may give this a stab so I can shift the performance curve around depending on what type of driving I am doing. Shorter for high RPM track sessions, longer for autocross where you stay in gear at turns and need lots of grunt t get up to speed again.

 

With the stack you got the step in the inlet is not good at all. Airflow will stop being laminar at the break and it will also cause a secondary reflection of the shock wave that is bouncing back and forth between your intake valve and the mouth of the trumpet. The transition between the trumpet and the carb inlet needs to be as smooth as possible.

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